# Phase Change Materials for Cold Thermal Energy Storage applications: A critical review of conventional materials and the potential of bio-based alternatives

Zakaria Ouaouja, Abdellah Ousegui, Cyril Toublanc, Olivier Rouaud, Michel Havet

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## To cite this version:

Zakaria Ouaouja, Abdellah Ousegui, Cyril Toublanc, Olivier Rouaud, Michel Havet. Phase Change Materials for Cold Thermal Energy Storage applications: A critical review of conventional materials and the potential of bio-based alternatives. Journal of Energy Storage, 2025, 110, pp.115339. 10.1016/j.est.2025.115339. hal-04886227

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Submitted on 13 Nov 2025

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## Review Article

# Phase Change Materials for Cold Thermal Energy Storage applications: A critical review of conventional materials and the potential of bio-based alternatives

Zakaria Ouaouja<sup>a,b,*</sup>, Abdellah Ousegui<sup>b</sup>, Cyril Toublanc<sup>a</sup>, Olivier Rouaud<sup>a</sup>, Michel Havet<sup>a</sup>

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### ARTICLE INFO

**Keywords:**

Bio-based phase change materials

Latent heat

Cold Thermal Energy Storage

Refrigeration systems

Cold chain

Perishable food storage

### ABSTRACT

The integration of Phase Change Materials (PCMs) as Cold Thermal Energy Storage (CTES) components represents an important advancement in refrigeration system efficiency. These materials have demonstrated significant capabilities in storing and releasing thermal energy, leading to improved system performance and reduced energy consumption. Conventional PCMs such as water/ice, hydrated salts, and paraffin are commonly used in CTES applications due to their favorable thermal properties and/or cost-effectiveness. This review paper explores the benefits and performance of integrating conventional PCMs in various refrigeration systems. It thoroughly discusses the effects of PCM integration on energy consumption, temperature stabilization, storage product quality, and greenhouse gas emissions.

While conventional PCMs are widely used in CTES applications, there is growing interest in exploring sustainable alternatives. Bio-based PCMs, derived from biomass and bio-waste materials, have shown promise as thermal storage candidates. Although these materials have been extensively studied for building applications, their potential in CTES applications remains largely unexplored. This paper also provides a detailed evaluation of bio-based materials based on their phase change temperature and latent heat, assessing their suitability for use in CTES applications.

Through this extensive review, the paper provides insights into the current state and future potential of PCM technology in CTES, highlighting both the proven benefits of conventional PCMs in enhancing refrigeration system efficiency and the potential sustainability of bio-based PCMs.

## 1. Introduction

Over the past decade, the global population has experienced rapid growth, increasing from 7.38 billion to 8.16 billion individuals within just ten years [1]. Current projections suggest that this growth trend will continue in the coming years. This major demographic growth presents many challenges, one of the most critical being the growing demand for fresh food to sustain the rising number of people. However, meeting this demand is not only testing the capacity of the world's food systems but also contributing to another major problem: food waste. Studies indicate that in 2022, approximately 32 % of all food produced worldwide was wasted, with losses occurring at multiple points within the supply chain [2,3]. Specifically, 13 % occurred during early supply stages, from post-harvest up to, but not including, retail. While the remaining 19 % is

wasted at later stages, including retail, food service, and household sectors. This represents a substantial 1.05 billion tonnes of wasted food annually, equating to an average of 132 kg/person/year. Notably, household waste accounts for the largest share at 79 kg/person/year, followed by the food service sector at 36 kg, and the retail sector at 17 kg/person.

Over time, humans have developed various methods to preserve food and extend its shelf life. These techniques range from traditional approaches like open sun drying and smoking to more advanced methods such as solar dryer systems, canning, coating, refrigeration/freezing, and the use of food additives etc.... [4]. However, these preservation techniques often present challenges: dried foods lose their shape and flavor, while canning is a cost-effective technique [5]. Additionally, temperature control is a crucial factor in maintaining the freshness of perishable goods. For this reason, refrigeration systems are widely

<footnote><sup>a</sup> Oniris, Nantes Université, CNRS, GEPEA, UMR 6144, F-44000 Nantes, France</footnote>

<footnote><sup>b</sup> RIPA, Département de Physique, Faculté des Sciences, Université Moulay Ismail, Meknès, Morocco</footnote>

<footnote>* Corresponding author at: Oniris, Nantes Université, CNRS, GEPEA, UMR 6144, F-44000 Nantes, France.
E-mail addresses: zakariaouaouja@gmail.com, zakaria.ouaouja@oniris-nantes.fr, zakaria.ouaouja@edu.umi.ac.ma (Z. Ouaouja).</footnote>
Nomenclature

Acronyms

<table><tr><td>A-CWO</td><td>Acetone-coffee waste oil</td></tr><tr><td>CNT</td><td>Carbon nanotubes</td></tr><tr><td>COP</td><td>Coefficient of performance</td></tr><tr><td>CTES</td><td>Cold thermal energy storage</td></tr><tr><td>CWO</td><td>Coffee waste oil</td></tr><tr><td>DSC</td><td>Differential scanning calorimetry</td></tr><tr><td>E-CWO</td><td>Ethanol-coffee waste oil</td></tr><tr><td>FAEs</td><td>Fatty acid esters</td></tr><tr><td>FAs</td><td>Fatty acids</td></tr><tr><td>GHG</td><td>Greenhouse gas</td></tr><tr><td>GnP</td><td>Graphene nano-platelets</td></tr><tr><td>H-CWO</td><td>Hexane-coffee waste oil</td></tr><tr><td>HDP</td><td>High-density Polyethylene</td></tr><tr><td>IIR</td><td>International institute of refrigeration</td></tr><tr><td>PCM</td><td>Phase change materials</td></tr><tr><td>PG</td><td>Propylene glycol</td></tr><tr><td>P-S acids</td><td>Palmitic-stearic acids</td></tr></table>

<table><tr><td>SA</td><td>Sodium alginate</td></tr><tr><td>TES</td><td>Thermal energy storage</td></tr><tr><td>TEV</td><td>Thermal expansion valve</td></tr><tr><td>GWG</td><td>Glycine-water-graphite</td></tr><tr><td>UCO</td><td>Used cooking oil</td></tr></table>

Symbols

<table><tr><td>c<sub>p</sub></td><td>Specific heat</td></tr><tr><td>m</td><td>Mass</td></tr><tr><td>Q<sub>L</sub></td><td>Latent energy</td></tr><tr><td>Q<sub>S</sub></td><td>Sensible energy</td></tr><tr><td>T</td><td>Temperature</td></tr><tr><td>Δh</td><td>Latent heat</td></tr></table>

Subscripts

<table><tr><td>L</td><td>Latent</td></tr><tr><td>l</td><td>Liquid</td></tr><tr><td>m</td><td>Melting</td></tr><tr><td>S</td><td>Sensible</td></tr><tr><td>s</td><td>Solid</td></tr></table>

implemented around the world, playing an essential role in food supply chains. Different studies have reported that there are approximately 0.05 million cold rooms [6], 5 million refrigerated trucks [6–8], 1.2 million containers [6–8], 2000 million domestic refrigerators [6,9], and 120 million commercial refrigerators [6]. This extensive network of

refrigeration units ensures that temperature-sensitive products remain viable throughout the storage and distribution stages, thereby helping to meet the demands of various sectors [10,11].

These refrigeration systems require substantial amounts of electrical energy to operate continuously, contributing significantly to global

<figure><img src="image_5.png" /><figcaption>Fig. 1. (a) Electricity production by source between 1985 and 2022. (b) Distribution of electricity production by sources for the year 2022. (c) Greenhouse emissions for different sectors between 2019 and 2022. (d) Greenhouse emissions for different sectors for the year 2022. Data converted into graph [12,13].</figcaption></figure>
electricity consumption. Throughout history, electricity generation has relied heavily on non-renewable energy sources (Fig. 1(a)). Thus, the cold chain sector indirectly influences greenhouse gas (GHG) emissions. Coal, in particular, has been a predominant source, contributing to around 35.7 % of the global energy generation in 2022 (Fig. 1(b)) [12]. Consequently, the power generation sector remains a major contributor to Greenhouse gas emissions (GHG). Fig. 1(c, d) provides further clarity by showing the contribution of power production to GHG compared to other sectors between 2019 and 2022. It is noteworthy that this sector accounted for a significant share, contributing to approximately 42.2 % of global GHG emissions in 2022, equivalent to 14.7 GtCO₂ [13].

Due to their reliance on electricity, cold chain equipment has contributed significantly to approximately 261 million tonnes of CO₂ emissions [14]. Among these emissions, about 60 % are indirect emissions due to electricity consumption (representing 281 TWh). This corresponds to approximately 156 million tonnes of CO₂. On the other hand, direct emissions are responsible for 22 % (57.4 MtCO₂) and 18 % (47 MtCO₂), due to refrigerant leakage and diesel usage respectively.

Hence, to mitigate the environmental side effects of refrigeration systems, it is highly beneficial to minimize their energy usage. This can be achieved by improving the thermal insulation of compartments, using high-efficiency compressors, and enhancing heat transfer in evaporator and/or condenser units [15,16]. Another passive option that has gained attraction is the integration of PCMs into different components of refrigeration systems. This technique has been proven to enhance the efficiency of refrigeration systems.

In recent years, various studies have been conducted to evaluate the effectiveness of this technique in different systems, including cold rooms [17,18], domestic and commercial refrigerators and freezers [19–23], refrigerated trucks [24–29], refrigerated containers [30], and refrigeration plants [31–33]. These studies have demonstrated that PCMs can be a viable alternative for better energy usage management. For this reason, Oró et al. [34] conducted a survey based on several published studies to quantify the potential energy and financial benefits of incorporating PCMs into refrigeration systems. Their analysis projected a 27.4–136.4 TWh reduction in annual total energy consumption, equivalent to 4.5–22 % savings. These energy savings could also ensure economic benefits, yielding 4.43 to 28.55 billion euros in annual savings.

CTES systems with PCM represent an innovative approach for efficient and sustainable cooling applications. This technology entails a cyclical process involving two sequential stages: charging and dis-

charging. During the charging stage, the refrigeration unit absorbs heat from the PCM, causing it to transition from liquid to solid phase (solidification), and thus stores cold thermal energy as latent heat. Once the PCM is completely solidified, the refrigeration unit is not working, allowing the stored cold energy to be re-used and cool the refrigerated case by absorbing heat. This causes the PCM to reverse the process and transition back to the liquid phase (melting/discharging process). Through continuous repetition of these cycles, a stable temperature can be maintained inside the refrigeration chamber, even when the refrigeration unit is not operating [35,36]. Fig. 2 provides a schematic representation of the operating principle of PCM during the phase change process. The overall energy is determined by: sensible heat, which affects the material temperature without changing its phase; and latent heat, which represents the energy required to change the material’s physical state from one phase to another, all while maintaining a constant temperature ($T_m$), assuming that the material is pure. While, for an impure material, this transition occurs over a temperature interval ($T_{m1}$, $T_{m2}$) [37–39]. The total amount of stored energy is formulated by the following formula [39–41].

$$Q_{PCM} = Q_{S(l)} + Q_{L} + Q_{S(s)} = mc_{p(l)} \int_{T_{l}}^{T_{m1}} dT + m \int_{T_{m1}}^{T_{m2}} dh + mc_{p(s)} \int_{T_{m2}}^{T_{s}} dT \quad (1)$$

where $Q_{S(s)}$ and $Q_{S(l)}$ represent the sensible energy at solid and liquid states. While $Q_L$ is the latent energy. In addition, $T_s$, $T_l$, $c_p(s)$, and $c_p(l)$, are temperature and specific heat of the material at solid and liquid states, respectively. The notation ($T_{m1}$, $T_{m2}$) represents the Phase Change Temperature (PCT).

Fig. 3 gives an overall comparison of the thermal properties of PCMs categories: organic, inorganic, and eutectics, each evaluated based on different key properties. Each PCM classification performance is represented on a scale of 0 to 3 points, with 0 being the lowest score and 3 the highest. Organic PCMs consist of carbon chains and are further categorized into paraffin and non-paraffin. Paraffin PCMs are comprised of alkane chains ($C_nH_{2n+2}$) derived from petroleum [42]. On the other hand, and as its name indicates, Non-Paraffinic PCMs constitute the rest of the organic PCMs. They are mostly derived from bio-sources materials, such as fatty acids, sugar alcohols, and fatty esters [43]. Inorganic materials are classified into two subgroups: hydrated salt (Salt, nH₂O) and metallic [44,45]. The third category is Eutectics materials, which

<figure><img src="image_6.png" /><figcaption>Fig. 2. Representation of the PCM temperature as a function of energy during phase change transition.</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>Fig. 3. Thermal properties comparison of PCM categories. Data converted into graph [50].</figcaption></figure>

are a mixture of organic and/or inorganic substances [46,47]. These materials are available at a wide range of temperatures and can be used for low-temperature applications such as cold chain and refrigeration sector in which a PCT varies from –70 °C to 15 °C [46–48]; Medium temperature PCMs (20 °C to 80 °C) commonly used in building and electronic application [46–49]. Finally, the high-temperature PCMs characterized by a high melting temperature that is higher than 80 °C are generally used for high-temperature applications including solar-thermal power plants [46–48].

The cost of final PCM products is influenced by several essential factors. The primary elements affecting the overall expense include the type (organic, inorganic, bio-based, etc.) and processing of raw materials, as well as encapsulation methods (macro, micro, or nano-encapsulation). Additionally, the volume purchased and associated shipping fees play significant roles in the final pricing. Among the organic materials, petroleum-based paraffin is generally considered an economical option [51–53], while high-purity laboratory-grade paraffin is more expensive [54]. Salts are recognized as the most cost-effective raw material for PCMs [55–57]. Despite this, the final price of commercial hydrated salts PCMs is considerably higher due to the added

costs of production and processing [51,53,58–60]. Bio-based PCMs, which are increasingly gaining attention [54], provide a moderately priced alternative [61–63].

The encapsulation process significantly influences the final product cost. The price varies based on both the encapsulation material (plastic or metal-based) and the chosen technique: macroencapsulation (>1 mm), microencapsulation (0–1000 µm), or nanoencapsulation (0–1000 nm) [64,65] (Fig. 4). Macroencapsulation, the simplest method, involves containing PCMs in plastic (HDPE) or metal containers (aluminum, copper) and represents approximately 20 % of total costs [55]. Microencapsulation, which involves coating PCM particles with polymer shells at the microscale, is more expensive, accounting for 50 % of the final product cost [37,55,66]. While microencapsulation can increase PCM viscosity, researchers are exploring nanoencapsulation as a potential solution to this limitation [67].

While the cost and encapsulation methods of PCMs are important considerations for their production and commercialization, these materials also face significant technical challenges. Addressing these challenges is essential to improving their performance and expanding their practical applications. Numerous reviews have extensively covered the practical challenges associated with PCMs and the various strategies employed to mitigate these issues, more details on these matters can be found in the following papers [17,39,71–73]. Key challenges include low thermal conductivity, the supercooling effect, phase segregation, and the corrosiveness to encapsulation materials.

The low thermal conductivity of PCMs presents a significant challenge. Researchers have primarily studied two strategies to address this drawback [17,37,42,72]. The first approach involves introducing high thermal conductivity nanoparticles, which can be either carbon-based or metal-based [68,74–86]. The second strategy focuses on enhancing the heat transfer surface area of the PCM through various techniques. These methods include: implementing structured fins, integrating heat pipes, utilizing porous materials such as metal or carbon foams, and employing advanced encapsulation technologies like micro- and nanoencapsulation [37,66,87–95].

Supercooling and phase segregation further complicates PCM performance by causing delays in latent heat release due to the metastable nature of liquid PCMs that solidify below their freezing temperature [17,96]. Inorganic PCMs, specifically hydrated salts are characterized by

<figure><img src="image_8.png" /><figcaption>Fig. 4. (a) Plastic and metallic macroencapsulation [68]. (b) SEM images of microencapsulate of hydrated salt [69]. (c) TEM image of paraffin/polystyrene non-ocapsules, creative commons [70].</figcaption></figure>
a high supercooling degree compared to the organic PCMs. These latter are characterized by less to no supercooling effect [72,96]. To mitigate these issues, nucleating agents have been employed to stabilize the phase change process and minimize supercooling and segregation [17,72,97–99]. Research into various nucleating agents, including thickening agents [100,101], nanocomposites [102–107], porous materials [88,89,108], and microencapsulation [109], has provided promising results.

Material compatibility between PCMs and their encapsulation presents another critical challenge. Studies highlight that while metals like aluminum, brass, copper, and steel exhibit varying degrees of compatibility for different salt hydrates PCM, stainless steel is the most suitable material for all types of PCMs, organic and inorganic [17,68,110–112].

While the strategies above have demonstrated efficacy in enhancing PCM properties, they also introduce additional challenges. For instance, the addition of nanoparticles and thickening agents can lead to a reduction in latent heat capacity – due to the non-phase changing nature of nanoparticles [46,113,114] – and increased viscosity, which hampers heat absorption and natural convection [100,104,115]. Fig. 5 comprehensively analyzes the effect of different additives on the thermal conductivity and latent heat of different PCMs. It can be seen that the concentration and type of the additives are the key factors in enhancing

or reducing thermal conductivity and latent heat, respectively. This insight is crucial for the targeted design and optimization of PCMs for specific applications, where a trade-off between enhancing thermal conductivity and keeping latent heat capacity may be required. More details are presented in Table 1 in Appendix A.

Fig. 6 gives an overview of the type of PCMs available in the market for CTES (see Table 2 in Appendix B for more details). The distribution of data points shows that the majority of the commercial PCMs fall within the hydrated salts and paraffin. These PCM types have gained popularity due to their low melting point. The melting point of paraffin depends on the number of carbons in the carboxylic chain, ranging from –52 °C to 5 °C. On the other hand, the melting point of salt solution PCMs decreases as a function of the concentration and type of salt. It ranges between –86 °C and –1.6 °C. In addition, these materials – paraffin and hydrated salts – exhibit sharp melting points and good latent heat that varies between 155 and 300 J·g⁻¹ for paraffin and 116–314 J·g⁻¹ for salt solutions [39,116,117]. However, it is important to note that they also have some drawbacks such as flammability, corrosiveness, high supercooling degree effect, and phase segregation issues [39,72,116]. It is worth noting that numerous research efforts have focused on water/ice as a PCM alternative, given its advantageous properties such as high latent heat capacity, cost-effectiveness, widespread availability, and

<figure><img src="image_9.png" /><figcaption>Fig. 5. Effect of additives on (a) thermal conductivity, (b) latent heat. Data converted into graph [17,37,39,42,68,71–85,88–94,96–101,108,109].</figcaption></figure>
<figure><img src="image_10.png" /><figcaption>Fig. 6. Melting temperature vs. latent heat for various commercial PCMs. Data converted into graph [51,58–60,130–139].</figcaption></figure>

environmental compatibility [21,118–129].

In recent years, bio-based PCMs have attracted the attention of researchers as they offer a sustainable and environmentally friendly alternative to petroleum-based paraffin PCMs. These materials are derived from plant or animal sources, making them available and affordable. Moreover, they possess desirable characteristics such as non-toxicity, less flammability, thermal and chemical stability, biodegradability, and oxidation resistance [140,141].

According to the database [142,143], there has been a significant number of research on bio-based PCM between 2007 and 2023 as presented in the line graph in Fig. 7(a). Specifically, 281 papers have been published during this period, in which articles represent the majority at 81.5 %, followed by a smaller percentage for conference papers, reviews, and book chapters, representing 10.7 %, 6.8 %, and 1.1 %, respectively (doughnut chart in Fig. 7(b)). The pie chart in Fig. 7(c), classifies these publications into different subject areas, revealing that a significant portion of the research is concentrated within the Engineering, Energy, and Material Science fields (63.9 % combined), whereas only 0.9 % is dedicated to the Agricultural subject area. This presents a potential opportunity for further exploration of the application of bio-based PCMs within the Agricultural field.

As mentioned above, only 19 papers (6.8 %) of the total research on bio-based PCMs, and Fig. 7(d) presents a network visualization of keywords used in these review articles, highlighting the areas of application and the growing interest in such sustainable materials. In this visualization, nodes represent different keywords, while the size of each node corresponds to the frequency of its occurrence. It can be seen that the “bio-based” node is linked to keywords such as “buildings” and “buildings applications” emphasizing the application of bio-based PCM in building-related contexts.

Recent literature reviews [62,144,145] highlight the increasing interest in bio-based PCMs as sustainable alternatives to petroleum-based PCMs. While these existing studies provide comprehensive analyses of bio-based PCMs across energy storage applications including building, photovoltaic, and electronic sectors, they exhibit notable limitations. Specifically, few publications have investigated the integration of bio-

based PCMs in CTES systems. Consequently, previous reviews offer superficial discussions regarding the potential of bio-based PCMs in CTES, with insufficient exploration of material properties suitable for such applications. Our current study aims to address this gap by first providing a comprehensive examination of integrating PCMs in CTES systems. Specifically, the review explores the benefits and performance of conventional PCMs across various refrigeration applications. The paper evaluates the effects of PCM integration on key metrics, including energy consumption, temperature stabilization, storage product quality, and greenhouse gas emissions. Secondly, the review conducts an extensive examination of thermal characteristics for promising materials derived from biomass and bio-waste, critically evaluating their potential suitability for CTES applications — an area currently characterized by minimal experimental investigations. Through this comprehensive analysis, the study aims to provide significant insights into the current state of PCM technology for CTES systems and pave the way for the potential future of bio-based alternatives in the cold chain industry.

The paper is organized into four main sections, beginning with an introduction to set the context. The second section provides a detailed examination of the applications and effects of PCMs in refrigeration systems. It explores the impact of PCM integration on various aspects, including energy consumption, coefficient of performance, air temperature regulation, and the influence of PCM properties such as PCT, thickness, positioning, PCM container materials, and fins. This section also addresses the impact of PCMs on stored products and CO2 emissions, providing a complete view of their role in refrigeration efficiency. The third section provides a critical overview of potential bio-based materials and wastes that could be used as phase change materials for cold energy storage applications. It categorizes these materials into different bio-based PCM classes and offers an in-depth analysis of their thermal properties, such as latent heat and PCT. Additionally, this section also outlines the advantages and disadvantages of each PCM category. This analysis provides valuable insights into the potential of bio-based PCMs for enhancing the efficiency and sustainability of refrigeration systems. It aims to bridge the gap in the literature regarding bio-based materials for cold energy storage applications. The paper
<figure><img src="image_11.png" /><figcaption>**Fig. 7.** (a) Quantification of research publications investigating bio-based phase change materials from 2007 to 2023. Adapted from [142,143]. (b) The doughnut chart presents the distribution of these publications categorized by document type. Adapted from [142,143]. (c) The pie chart illustrates their distribution across different topic areas [142,143]. (d) Keyword co-occurrence network for bio-based phase change materials. Data converted into graph using VOSviewer [142,143].</figcaption></figure>

concludes by synthesizing the findings, presenting key perspectives on the potential of bio-based PCMs in enhancing the efficiency and sustainability of the cold chain sector, while also identifying areas for future research.

## 2. Application and effect of PCM in refrigeration systems

Many researches have focused on integrating PCMs in different refrigeration systems such as domestic and commercial refrigerators, cold chains, walk-in freezers, and warehouses. They can be incorporated
into different parts of the refrigeration system: in outer walls as thermal
insulators, as CTES systems, and as heat exchangers. Unfortunately, bio-
based PCMs have not yet gained significant traction to be used as CTES.
Despite this, other varieties of PCMs have demonstrated their
effectiveness.

This section presents an extensive analysis of the efficacy demon-
strated by various strategies, highlighting the substantial benefits of
incorporating PCMs into refrigeration systems. The integration of PCMs
shows promising results in multiple key performance indicators,
including the enhancement of coefficient of performance (COP),
reduction in energy consumption, and mitigation of temperature fluc-
tuations. Table 3 in Appendix C provides a summary of the findings
reported in the various studies examined in this section.

2.1. Effect on energy consumption and COP

2.1.1. PCMs as thermal insulation (as thermal shield)

PCMs have been used as Thermal Energy Storage systems (TES) to
enhance the thermal insulation of refrigeration systems [146,147]. In
this approach, PCMs act like a thermal shield, absorbing surrounding
heat and storing it as latent heat through the process of changing from
solid to liquid phase. This transition helps to minimize and shift the peak
rate of heat transfer and temperature during the day, thereby reducing
the power consumption of refrigeration systems. The PCM's optimal

melting temperature for this approach should be close to the sur-
rounding temperature.

Fioretti et al. [146] examined the impact of the paraffin layer (Commercial PCM; 35 °C) added to the external surfaces of a walk-in freezer as a thermal insulator as illustrated in Fig. 8(a). The objective was to minimize and shift the peak heat transfer. The experiment took place over two summer days under outdoor conditions. The results showed that the PCM acts as an energy storage system that absorbs and shifts the heat flow, effectively, enhancing the thermal insulation of the walk-in freezer. The addition of PCM resulted in a significant difference in peak temperatures between the PCM inner surface (denoted as RN5 in Fig. 8(b)) and the PCM outer surface (designated as RN4 in Fig. 8(b)). Specifically, the peak temperature at RN5 was found to be 12–14 °C lower than the peak temperature at RN4. Additionally, this peak was shifted by approximately 4–5 h due to the presence of PCM. They also compared the temperature value at RN5 with that of the external surface of the reference case (represented by R4 in Fig. 8(c)). The temperature in this case was 7–8 °C lower than the reference one. On the other hand, there was no significant difference between the internal air temperature of the reference case (at R5) and the PCM case (at RN6), as the refrigeration system effectively regulated and maintained a constant internal temperature. Fig. 8(d) provides a comparative analysis of the heat flux on the walk-in freezer wall equipped with phase change material (PCM) compared to the reference scenario for two distinct days. The results

<figure><img src="image_12.png" /><figcaption>**Fig. 8.** Illustration of (a) experimental setup of PCM layer implementation; schematic representation of cold room: (b) with PCM, (c) without PCM; (d) thermal flux through cold room wall for 2 days.
Adapted from [146].</figcaption></figure>
demonstrate a significant reduction in the heat flux peak as well as a delay in its occurrence when employing PCM. Specifically, the value of the peak heat flux was decreased by 5.55–8.57 % and shifted by 3.5–4.5 h relative to the reference case.

Copertaro et al. [147] developed a numerical model investigating the energy behavior of a refrigerated container envelope incorporated with nine different PCMs laminated between steel and polyethylene panels to choose the suitable PCM for the Italian climate. Fig. 9 illustrates the evolution of the heat load within the container during 24 h. We can see that using PCMs reduces and shifts the peak heat gain. The PCM RT35HC (PCT 35 °C) is found to be most effective in the Italian climate. It offers significant benefits by reducing and shifting the heat load peak by 20–25 % and 2–3 h, respectively. As a result, the daily energy usage is reduced by 4.55–4.74 % compared to a standard container.

### 2.1.2. PCMs as cold thermal energy storage system

Many studies have been conducted using PCMs to store cold energy when it is in excess and used when needed. This strategy can reduce energy usage according to two main operating approaches: Full storage (Fig. 10(a)), in which the refrigeration system is completely shut down and the cooling load is provided by the PCM. This shifts the energy consumption from on-peak to off-peak periods. The PCM is then charged during off-peak hours using a refrigeration system cooling load. Partial storage: In this case, the PCM provides a part of the cooling loads, and the rest is covered by the refrigeration system. Partial storage is further subdivided into two types: Load leveling (Fig. 10(b)) and Load limiting (Fig. 10(c)). In load leveling, the refrigeration system is running all day, and the PCM provides a cooling load when the demand is greater than the refrigeration system output. The PCM can be charged when the demand is less. For the load limiting strategy, the PCM provides a part of cooling loads during on-peak hours and the rest is covered by the

<figure><img src="image_13.png" /><figcaption>**Fig. 9.** Comparative analysis of internal heat load in refrigerated containers using various PCMs in different climates. Adapted from [147].</figcaption></figure>
<figure><img src="image_14.png" /><figcaption>Fig. 10. Operating strategies of PCM integrated into a refrigeration system.</figcaption></figure>

refrigeration system. The PCM is charged again during off-peak hours.

In this strategy, it is ideal that the material's PCT closely matches the refrigeration system set point. This temperature depends on the type of the stored product, for deep-frozen products like meat, a temperature around -30 to -25 °C would be suitable, while for fresh products such as tropical fruits a temperature around 8 to 15 °C would be appropriate [72,148].

#### 2.1.2.1. Full-storage.
Studies have proven that the full-storage approach can reduce energy use by 18-86.7 % compared to the baseline,

depending on the type of PCM used and the refrigeration system.

ASWB Engineering [149] investigated the performance of two distinct walk-in freezers 1 and 2 integrated with PCM. The freezers were maintained at -15 °C and -19 °C, respectively. The primary objective of this investigation was to evaluate the feasibility of incorporating PCMs into these cold storage environments to optimize energy efficiency and reduce cooling costs. The PCM was installed above the storage rack in both walk-in freezers where the supply air fans were able to recharge the PCM. The results revealed that using PCMs can minimize the energy consumption for both facilities. Fig. 11(a-c) presents a comparative

<figure><img src="image_15.png" /><figcaption>Fig. 11. Freezer 1: (a) daily compressor run time per cycle. (b) Daily defrost energy. (c) Average internal air temperature. (d) Power consumption of Freezer 2 before and after the PCM.
Adapted from [149].</figcaption></figure>
evaluation of the performance of the freezer 1 with and without PCM. The results demonstrate that incorporating PCM into the design significantly alters the freezing process. Specifically, it is observed that the inclusion of PCM shortens the duration of each refrigeration cycle compared to the base model, which operates for longer intervals between cycles, as shown in Fig. 11(a). This reduced run time translates to fewer defrost cycles, resulting in a more consistent temperature profile (Fig. 11(b, c)). Notably, this resulted in a remarkable 30% reduction in total energy consumption. For the freezer 2 case, the PCMs were charged during the daytime relying on photovoltaic energy, and released the stored cold energy at night, enabling the refrigeration system to be entirely turned off for 10 h. As depicted in Fig. 11(d), before the installation of the PCMs, the refrigeration unit operated continuously for 24 h (represented by the blue line), whereas afterward, it only ran for 10 h (represented by the red line). This innovative approach resulted in a remarkable decrease in daily energy consumption of 27.42% and an annual reduction of 39%.

PCMs have been applied in cold chain transportation including refrigerated containers. Tong et al. [30], applied 10 PCMs (Commercial PCM; 5 °C) plates to a refrigerated container. The PCMs plates are embedded with coiled tubes connected to the refrigeration unit, allowing heat transfer fluid (–10.7 °C) to circulate during the charging process before transportation (as shown in Fig. 12(a)). Subsequently, the container was fully loaded with fresh fruits and vegetables and then transported for approximately 2500 km in 96.4 h. The energy

consumption, operating costs, and CO₂ emissions of the PCM-based container were compared to those of a diesel-powered refrigerated container to evaluate their performance during the same delivery process. The authors reported that by charging the PCMs only once, the container with PCMs could maintain the internal temperature stable for 94.6 h under outdoor conditions ranging from 13 to 35 °C.

Fig. 12(b, c) shows the actual temperatures recorded within the container throughout transit, highlighting the remarkable ability of the PCMs to preserve a steady interior temperature even when exposed to significant external temperature fluctuations. The results also showed that the new container only consumed an average of 1 kW of power throughout the entire charging cycle to cover the whole delivery journey. In comparison, the conventional diesel-powered container consumed approximately 7.5 kW (correspondent to 202.4 L of diesel fuel) to cover the same delivery distance (2500 km; 96.4 h), thereby resulting in a significant reduction of 86.7%. Furthermore, these energy efficiency gains translate into remarkable financial benefits, with total cost savings of 91.6%, as well as reducing GHG emissions by 78.5%.

#### 2.1.2.2. Partial-storage.
Research focusing on the partial-storage approach has shown that it can reduce the energy usage of refrigeration systems by varying amounts, depending on the system and PCM types, ranging from 4.4% [150] to 77.5% [118]. Hence, the COP was enhanced by 8% to 60% [151].

Viking Cold Solutions, Inc. (commercial study) [152], installed

<figure><img src="image_16.png" /><figcaption>**Fig. 12.** (a) The locations of the PCM plates on the container. (b, c) The variation of air temperatures within the container. Adapted from [30].</figcaption></figure>
plastic containers filled with salt-water PCM on the ceiling next to the evaporator fans of a cold room. This position was chosen to ensure that the PCM plates could charge quickly and provide natural convection cooling when the compressor is off. The PCMs were fully charged during the night and released cold energy during the daytime, thus supplementing the refrigeration system and reducing the energy consumption of the walk-in freezer. During the 10-day study period, the results were favorable, with net consumption reduced by 18 % compared to the baseline. Power consumption during peak periods dropped from 6 kW to <1 kW representing an 85 % reduction. Correspondingly, the operation time was significantly shortened by 60 %, equating to a total saving of 6.5 h of energy consumption.

In another study, Viking Cold Solutions, Inc. [153] implemented PCMs at the topmost rack of a frozen food storage facility. During the evening hours (off-peak period), the PCMs were charged by losing their latent heat to the refrigeration unit. Meanwhile, during the daytime (on-peak period), these materials are employed to partially substitute the refrigeration system and supplement the cooling process by absorbing heat generated from freezer infiltration and thus controlling temperature fluctuations. Fig. 13 represents the daily energy consumption of the warehouse without and with PCMs. The findings indicate that during the on-peak period, the inclusion of PCMs resulted in a partial reduction in energy consumption, which lasted for nearly 12 h. This led to a decrease of 35 % in the overall daily energy usage. Moreover, the integration of PCMs also significantly lowered the peak period energy consumption by approximately 43 %, indicating their potential to optimize energy efficiency in warehouses.

## 2.2. Effect on air temperature

### 2.2.1. During normal operating conditions

The studies agreed that PCMs have a substantial impact not only on the refrigeration system efficiency but also on the internal air temperature within these systems. Experimental and numerical research proved that PCMs act as supplementary evaporators, keeping the temperature as stable as possible at all times [119,154,155]. This stabilization effectively reduces temperature fluctuations within the system, in contrast to conventional systems without PCM (Fig. 14(a)). Additionally, PCM reduces the sudden temperature rise caused by door openings, and defrost periods [120,156–162] leading to fewer compressor on-off cycles and thus less energy consumption. This section assesses the impact of integrating PCM on the internal temperature and energy performance during typical operation.

Principi et al. [163] placed a PCM heat exchanger with 6 containers filled with paraffin (Commercial PCM) and was placed next to the evaporator fans of the same cold room as used in the previous study [146]. The material was chosen with a PCT close to the operating temperature of the cold room, set at 5 °C. The experimental results show – as Fig. 14(b) illustrates – that during the compressor off time, PCM acted as an evaporator absorbing heat gain infiltrating from outside sources through the walls of the cold room, thereby avoiding rapid temperature rise and reducing fluctuations. As a result, fewer compressor on-off cycles were achieved. Specifically, over 2 h, the number of compressor cycles decreased from 13 cycles for the reference case to just 6 cycles for with PCM case (Fig. 14(c)). This has resulted in a 16 % reduction in electrical power consumption.

Visek in his work [164], directly placed the PCM slab in a household refrigerator to optimize the energy consumption. The measurements were taken during 24 h of operation under ambient conditions. Fig. 14 (d) illustrates the effect of the PCM on the internal temperature profile of the refrigerator. One can see that adding PCM has a favorable influence on reducing temperature fluctuations. This mitigation is achieved through prolonging the compressor off time. During this period, the PCM keeps cooling the compartment for 11.8 h. Consequently, the daily energy usage has been decreased from 197 Wh (Reference) to 186 Wh (With PCM), representing a reduction of 5.6 %.

Gado et al. [165] developed a mathematical model of a mini cold storage room. The studied PCM properties were those of a commercial PCM (hydrated salts), which has a PCT of –30 °C. The PCM plates were considered to be next to the evaporator fan. The internal temperature of the reference case fluctuates between –29 °C and –31 °C more frequently than the new case (Fig. 14(e)). This phenomenon can be primarily attributed to the thermal energy storage capabilities of the PCM. The PCM functions as a supplementary evaporator, absorbing heat as it transitions from its solid to liquid state. This phase transition process contributes to a more stable thermal environment and significantly extends the compressor off-time from approximately 4 min to 24 min. As a direct result, the number of on-off cycles was significantly decreased by 82 %, from 256 cycles per day without the PCM to 46 cycles per day when adding the PCM (Fig. 14(f)). Consequently, this reduction is translated into a decrease in daily energy consumption (10.53 %).

### 2.2.2. During opening door, defrost cycle, and power outage

The effectiveness of PCMs on internal temperature as well as energy consumption for different scenarios: normal operation (door is closed), door openings, defrosting, and electrical power loss were studied in

<figure><img src="image_17.png" /><figcaption>**Fig. 13.** Daily energy consumption of the facility. Adapted from [153].</figcaption></figure>
<figure><img src="image_18.png" /></figure>

<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /><figcaption>**Fig. 14.** (a) Numerical analysis of the impact of PCM on refrigerator internal temperature [162]. (b, c) Measured temperature and energy consumption comparisons with/without PCM integration [163]. (d) Experimental investigation of PCM's effect on air temperature in a domestic refrigerator [164]. (e, f) Numerical evaluation of PCM integration on temperature regulation and compressor energy consumption [165].</figcaption></figure>

<figure><img src="image_21.png" /></figure>

<figure><img src="image_22.png" /></figure>

<figure><img src="image_23.png" /></figure>

[157,158,160,161] and is discussed below.

Gin et al. [157] conducted an experimental study to assess the thermal and energy performance of a household refrigerator under various conditions (e.g., door opening and defrost cycle) throughout integrating PCMs. Ammonium chloride with a PCT of -15.4 °C was used as PCM and placed against the inner walls of the refrigerator. The results indicate that incorporating PCMs slows the rapid increase in internal air temperature within the refrigerator during compressor-off periods for both test scenarios. During the defrost phase (illustrated in Fig. 15(a)), the internal air temperature was found to be 11 °C lower in the novel refrigerator compared to the reference case. Furthermore, the defrost heating system runtime was observed to be shorter in the first scenario, lasting only 26 min compared to 28.5 min in the conventional case. The effect of PCM on the internal and product temperatures during power loss is illustrated in Fig. 15(b). The air temperature reaches -3 °C in only 4.4 h when no PCM is implemented, while it took 11 h to reach the same temperature for the new refrigerator. In terms of energy consumption, the authors reported that defrost and door openings increase power consumption by 15-21 % and 11-17 %, respectively. However, upon incorporating PCMs, the compressor was observed to run less frequently than in the standard freezer, leading to an 8 % and 7 % reduction in energy consumption during the defrost cycle and door opening tests, respectively.

Oró et al. [160] evaluated the impact of a PCM container on the thermal performance of freezers during door-opening and power outage scenarios. A sodium nitrate-based PCM (commercial PCM) characterized by a PCT of -22 °C was encapsulated in a stainless-steel plate and placed inside the cabinet. A series of door openings of 30 s each, were

conducted to study the internal temperature behavior of the freezer with and without PCM. The results showed that during 3 h of power interruption test, the presence of PCM allows significant thermal stabilization effects. The PCM-equipped freezer maintained the internal temperature within a range of 4-6 °C, as illustrated in Fig. 15(c). Moreover, the temperature of the stored products in the PCM-equipped freezer remained approximately 2 °C lower than those in the reference freezer, as depicted in Fig. 15(d). In addition, the authors reported that the PCM could slow down the rise of internal temperature during door opening tests by an average of 3 °C (Fig. 16(a)). These findings underscore the PCM's efficacy in thermal regulation during power disruptions.

A study conducted by Khan and colleagues [161] investigated the thermal performance of a domestic refrigerator enhanced with PCM panels under two critical scenarios: door opening events and power outages. The household refrigerator was integrated with organic PCM (with a PCT of 5 °C) encapsulated in a stainless-steel container. The experimental results demonstrated enhanced thermal stability in the PCM-equipped refrigerator prior to door openings, as illustrated in Fig. 16(b). After opening the doors, the internal temperature in the PCM-enhanced system peaked at approximately 9 °C, compared to 12 °C in the reference unit without PCM. During power outages, the PCM panels act as an additional evaporator and absorb heat inside the cabinet. This resulted in a temperature differential of 3 °C lower in the PCM-equipped unit compared to the reference case. Fig. 16(c, d) illustrates the thermal profiles of stored food items. One can see that the presence of PCM panels contributed to significantly reduced temperature fluctuations of the products, ensuring a better quality of the products.
<figure><img src="image_24.png" /><figcaption>**Fig. 15.** (a) Effect of PCM on internal temperature during defrost cycle [157]. (b, c, d) Effect of PCM on internal and product temperatures during power outage [157,160].</figcaption></figure>

## 2.3. Effect of PCM's phase change temperature

The PCT and latent heat capacity are crucial factors in selecting a PCM to ensure the desired food preservation temperature and the effectiveness of the adopted strategy.

If the PCMs are installed inside the refrigeration systems or on the evaporator, it is essential that their PCT align with the operational temperature range of the system, rather than being lower. This ensures that the PCM can effectively charge/discharge at the desired temperatures, thereby maintaining consistent temperature conditions. Alternatively, if the PCM is installed on the condenser, the PCT must correspond to the temperature range of the condenser to absorb heat efficiently and enhance the system's overall performance. Studies have proven that PCT has a positive influence on air temperature fluctuations within various refrigeration systems. They reported that the lower the PCT of the PCM, the lower the temperature fluctuations [119,121,122,147,151,159,166].

Fig. 17(a) illustrates the effect of PCT on the temperature within a refrigerated truck [24]. The case with a lower PCM melting point continues to cool the cabinet for long periods. However, if the PCT is not selected correctly, it would have a negative effect on the energy consumption and COP of the system. Fig. 17(b) presents the results of a study conducted by Azzouz et al. [151,162], in which they numerically evaluated the effect of the melting temperature of the PCM on the internal air temperature and the COP of a domestic refrigerator. The PCMs were placed behind the evaporator as shown in Fig. 17(c). The results show that the temperature inside the system and its COP increase as the PCM's PCT increases. The decrease in COP is due to the compressor working harder to drop the internal temperature and achieve the freezing point of the PCM. Therefore, the PCM must be carefully selected to meet the required cooling loads.

## 2.4. Effect on condensing/evaporating temperature

Condenser and evaporator are heat exchangers that release heat from the refrigerant to the outdoors and absorb heat from the environment being refrigerated, respectively. PCMs have been successfully integrated as supplementary heat exchangers in refrigeration systems, functioning as condensers and evaporators. This novel strategy globally enhances heat transfer efficiency at the refrigeration system's main heat exchangers leading to lower condensing temperature, and a higher evaporation temperature, as well as less fluctuation [117,121,122,164,166]. The PCT of the PCMs used in this tactic is recommended to be close to the condensing and evaporation temperatures. In addition, this approach enhances the COP of the refrigeration system by a percentage ranging between 17.6% to 27% [121,122,166–168], as well as reducing energy consumption by 7% to 21% [122,154,167,168].

Sonnenrein et al. [122] experimentally evaluated the influence of using PCMs on the thermal behavior and power consumption of household refrigerators. Four PCMs (water + aluminum encapsulation, paraffin + high-density polyethylene (HDP) encapsulation, paraffin + aluminum encapsulation, and copolymer PCM) were placed on the refrigerator condenser tubes. The impact of using PCMs on the refrigerator condenser temperature is shown in Fig. 18(a). The condenser inlet, mid, and outlet temperatures were significantly reduced. The maximum condenser inlet temperature was reduced by 3 °C and 8 °C using water and copolymer compound, respectively. The maximum temperature at the center of the condenser was also reduced by 5 °C when using water as PCM and 10 °C for the copolymer compound, while, the condenser outlet temperature was reduced by 5 °C (water) and by 8 °C (copolymer). In addition, and compared to the reference refrigerator, the energy consumption was reduced by 3 %, 5 %, 7 %, and 10 % when using water, paraffin + HDP, paraffin + aluminum, and
<figure><img src="image_25.png" /><figcaption>Fig. 16. (a, b) Effect of PCM on internal temperature during door openings [160,161]. (c, d) Effect of PCM on stored products [161].</figcaption></figure>

<figure><img src="image_26.png" /><figcaption>Fig. 17. (a) Simulated internal temperature when using PCM with different PCT [24]. (b) Variation of the COP and internal temperature of refrigeration system as a function of PCT. Adapted from [151]. (c) Illustration of domestic refrigerator integrated with PCM [151].</figcaption></figure>
<figure><img src="image_27.png" /><figcaption>**Fig. 18.** Effect of PCM on: (a) inlet, mid, and outlet condenser temperatures [122]; (b) evaporation temperature; (c) internal cabinet temperature [121]; (d) compressor on-off cycle [121,166].</figcaption></figure>

copolymer, respectively.

In other studies, Khan et al. [121,166] incorporated three different PCMs (water, sodium chloride with temperatures of -5 °C, and -10 °C) into the evaporator of a domestic refrigerator. The experimental results are represented in Fig. 18(b, c, d). It can be seen from Fig. 18(b, c) that the use of PCM effectively stabilizes the temperature fluctuations of both the internal and the evaporation temperatures leading to a reduction in the compressor run time (Fig. 18(d)). It was found that in comparison with the reference case, the compressor run time was reduced by about 2–36 % and 5–30 %, depending on the type of PCM and thermal load.

## 2.5. Effect of PCM thickness

Ezan et al. [123] developed a 3D CFD numerical model to investigate the influence of PCM slab thickness on the compressor run-time of a closed beverage cooler. Five PCM plates (water as the PCM; 2 to 10 mm thickness) were placed behind the evaporator of the cooler. The results were compared to the experimental measurements to validate the numerical model. The said predicts that a 2 mm thick PCM plate prevents the sudden temperature rise and keeps the air temperature inside the refrigerator almost constant at 3 °C, thus prolonging the compressor off period. Fig. 19(a) summarizes the effect of PCM thickness on the compressor functioning behavior. One can see that as the PCM thickness increases the off-time increases, from 98 min to 494 min for 2 mm to 10 mm PCM. However, the compressor running time has increased to charge the PCM, from 47 min to 202 min. In addition, the first temperature drop takes more time as the thickness rises, from 80 min (2

mm) to 280 min (10 mm). The model predicted that the compressor run-time ratio decreases as the PCM thickness increases, from 36 % (no PCM) to 26 % (6 mm PCM slab), which is approximately 28 % less. However, beyond 6 mm thickness, the PCM slab led to a higher compressor run-time ratio.

For the same reason, Azzouz et al. [151] modeled the PCM on the evaporator of a domestic refrigerator. This work modeled three PCMs with thicknesses of 2.5, 3.5, and 5 mm. The refrigerator's operating time and autonomy as a function of thickness were evaluated. The authors reported that the system's relative running time decreases as the PCM thickness increases, reaching a gain of 28.5 % to 32.6 % for the 2.5 mm and 5 mm PCM panels, respectively (Fig. 19(b)). The figure also indicates that the system autonomy was 4.7–8.5 h when using 2.5–5 mm PCM, respectively.

In a comprehensive parametric investigation, He et al. [169] examined the influence of PCM volume fraction on energy consumption within a refrigerated warehouse. The numerical study employed an on-shelf configuration, positioning PCM plates (hydrated salts; PCT-19/-17 °C) atop warehouse shelves. The study compared two operational control scenarios: a temperature-based control (Case 1) and a temperature-price-based control (Case 2), both cases without PCM integration. Fig. 19(c) illustrates the operational costs and percentage reductions for the refrigerated warehouse under these different conditions. Case 4 represented the PCM-integrated scenario, while Case 1 and Case 2 provided comparison points. Notably, the results revealed a significant relationship between PCM volume fraction and operational cost reduction. The analysis demonstrated that operational costs
<figure><img src="image_28.png" /><figcaption>**Fig. 19.** (a) Effect of PCM on compressor run time as a function of PCM thickness, table converted into graph [123]. (b) Refrigeration autonomy as a function of PCM's thickness [151].</figcaption></figure>

decreased substantially up to approximately 2 % PCM volume fraction, after which the improvements stabilized. In Case 4, the operational cost savings were remarkable — approximately 34 % lower compared to Case 1 and 22 % lower than Case 2. A similar trend emerged in electricity consumption, as shown in Fig. 19(d). Increasing PCM volume fractions led to noticeable consumption reductions, with improvements most pronounced up to around 2 %. At the highest PCM volume fraction (4 %), electricity consumption decreased by up to 15 %. These findings underscore the potential of PCMs when integrated with an energy management strategy for improving refrigerated warehouse energy efficiency. By enabling the storage and strategic utilization of cold energy during low-cost periods, PCMs offer a promising approach to optimizing energy performance and reducing operational expenses.

## 2.6. Effect of container's material and fins

The choice of PCM container material plays a crucial role in improving the heat transfer in PCM. For this manner, Rahimi et al. [170] conducted an experimental evaluation of the thermal and energy performance of a domestic refrigerator by using different encapsulation materials as well as incorporating fins. In these experiments, a metal container was filled and placed underneath the evaporator (Fig. 20(a)). Fig. 20(b) shows the comparison between the internal temperature of the reference refrigerator and the novel refrigerator with copper, aluminum, and steel PCM containers. It can be seen that placing a Metal-PCM slab affects the internal temperature fluctuation and thus the compressor's on-off cycles. Specifically, copper-PCM container yields optimal results by reducing the compressor run time ratio which is

defined as the ratio between On-time and the On-off cycle time [171]. As a result, energy usage has decreased by 7.33 %, 3.21 %, and 2.86 % for copper, aluminum, and steel containers respectively (Fig. 20(c)). Furthermore, the experimental investigation revealed that incorporating fins onto the PCM container (as depicted in Fig. 20(d)) led to a significant reduction in energy consumption, with decreases of 4.37 % (Config. 1), 7.23 % (Config. 2), 9.56 % (Config. 3) compared to the copper-PCM configuration (Fig. 20(e)). These findings demonstrate that the thermal conductivity of PCMs plays a crucial role in their efficiency, as it directly impacts the heat transfer rate and, consequently, the charging/discharging time [43,72,172].

In the study by Zarajabad et al. [124] both numerical and experimental investigations were conducted by placing PCM (water) on the evaporator of a domestic refrigerator. The PCM container was numerically modeled both with and without fins. The simulation results revealed that during periods of compressor downtime, the PCM can maintain the refrigerator temperature at the standard temperature (between 1 °C and 6 °C) for 30, 60, and 68 min for the no-fin, 1-fin, and 3-fin containers, respectively. In addition, the researchers found that the incorporation of fins enhanced the heat transfer within the PCM container as they increased the heat transfer surface area, leading to a shorter time required for the charging/discharging process. To validate the numerical model, the 3-fin container was experimentally tested in a domestic refrigerator. The experimental results showed that by using the 3-fin PCM container, the compressor running time was reduced by 45 min/day compared to the case without PCM. Specifically, it dropped from 4.32 h to 3.57 h. This corresponds to an energy savings of 17.4 %, as the new refrigerator (equipped with PCM) consumed 193.93
<figure><img src="image_29.png" /><figcaption>Fig. 20. (a) Image of the PCM container integrated into the evaporator. (b) Effect of PCM slab on the internal temperature. (c) Comparison between reference refrigerator and refrigerator integrated with PCM slab with different encapsulation metal, data converted into graph [170]. (d) Illustration of PCM container with different fins configurations. (e) Effect fins on energy consumption, data converted into graph [170].</figcaption></figure>

$kWh·year^{-1}$, whereas the reference refrigerator consumed 234.72 $kWh·year^{-1}$.

## 2.7. Effect of the PCM position and orientation

A series of experiments were conducted by Wang et al. [31–33] by installing different PCM-based heat exchangers in a refrigeration plant prototype. As shown in Fig. 21(a) the Eutectics PCM heat exchangers were installed between the system’s compressor and condenser (PCMA; 21 °C), the condenser and expansion valve (PCMB; 21 °C), and the evaporator and compressor (PCMC; 8 °C). The results showed that PCMA heat ex-changer acts like an extra condenser and decreases the temperature and pressure of the refrigerant before entering the condenser, thus, enhancing the COP of the refrigeration plant by 6 %. Using PCMB as a heat exchanger can improve the COP of the refrigeration system by 8 %. This gain is due to the decrease of the refrigerant temperature by the PCM (increases super-cooling) before entering the expansion valve. The PCMC has more benefits in terms of temperature stabilization and superheat reduction, factors that could potentially enhance the system’s COP. However, this configuration also results in a decreased refrigerant pressure at the compressor inlet. This reduction effectively negates any COP improvements, ultimately rendering the PCMC configuration the least efficient one.

Marques et al. [125] also conducted a CFD simulation of the previous

refrigerator configuration to investigate the temperature distribution inside the compartment. The PCM slab (water) was placed next to the evaporator in 3 different orientations: vertical, horizontal, and combined. Fig. 21(b) shows a comparison of the predicted temperatures inside the refrigerator with the 3 PCM orientations. A clear difference can be observed in the temperature profiles of each configuration. Specifically, the vertical orientation leads to a non-uniform temperature profile characterized by a cooler region on the bottom and a warmer area top part of the refrigerator. The average temperature of this configuration was 11.2 °C. The horizontal orientation, on the other hand, leads to a more uniform temperature distribution, with an average temperature of around 8.8 °C. Notably, the combination of both orientations proved to be the most effective configuration, leading to a highly uniform temperature profile with an average temperature of approximately 6 °C.

## 2.8. Effect on stored products

Refrigeration plays a crucial role in food preservation by providing a stable and cool environment to inhibit spoilage and extend shelf life. As previously discussed, incorporating PCMs into refrigeration systems helps to significantly reduce temperature fluctuations within the cabinet and regulate relative humidity levels, which are key factors affecting food quality [173,174]. Studies proved that PCMs are capable of
<figure><img src="image_30.png" /><figcaption>**Fig. 21.** (a) PCM heat exchanger integrated into refrigeration system, recreated based on [31]. (b) Comparison of the simulations between the different orientations of the PCM, adapted form [125].</figcaption></figure>

minimizing ice crystal formation, reducing weight loss, and maintaining the texture and color of stored products [30,158,175].

Gin et al. [158] used the same configuration as in [157] and investigated the effect of PCM panels on the internal temperature and temperature of the stored products (meat and ice cream) during repeated power losses (3 h) every 24 h over 2 weeks. The results showed that the PCM-based freezer had lower fluctuations in air and product temperature than the no-PCM freezer, leading to better food preservation. Fig. 22(a) represents the product temperature during a 3 h power loss. The PCM panels reduce the rate of temperature increase of the products, reaching –3 °C for the reference case, and –11 °C for the PCM-based freezer. Fig. 22(b) represents the effect of PCM on the meat exudate; one can see that without PCMs, the meat loses its quality quicker than in the presence of the PCM. The authors reported that after two weeks of PCM use, the meat drip loss was reduced from 17 % to 10 %. They also evaluated ice cream crystal size, which is proportional to temperature fluctuation amplitude. Specifically, larger temperature fluctuations lead to greater crystal size and affect the overall texture of the ice cream [26]. With PCM, there was a reduction in crystal size from 70–80 µm to 40–50 µm.

The previously reviewed paper in [30] has also examined the effect of PCMs in preserving the quality of perishable goods. Specifically, the quality assessment of four types of produce leaf lettuce, strawberries, mangoes, and lettuce. As shown in Fig. 22(c), visual assessment revealed no apparent deterioration or rot in the produce following transportation. In addition, the results revealed that the PCM container maintained a high internal relative humidity of approximately 80–90 %, which is optimal for preserving freshness. The qualitative inspection indicates

minimal changes in key quality parameters across all products. Specifically, hardness values remained stable for leaf lettuce, lettuce, and strawberry, with a slight increase observed for mango (from 3.44 to 4.76). Soluble solid content, a critical indicator of fruit ripeness and flavor quality [176], exhibited minimal changes, with the most notable decrease in mango (from 15.3 % to 14.3 %). pH levels remained consistent across all products, indicating maintenance of product acidity.

Rahimi-Khoigani et al. [175] studied the effect of tetradecane as PCM (paraffin; 6 °C) on mushroom quality preservation during a four-day storage period. The study evaluated three packaging scenarios: a reference package without PCM (LHSB), a package incorporating PCM (LHSW), and a PCM-enhanced package with fins (LHSI). The experimental results, as depicted in Fig. 23, demonstrated significant improvements in various quality parameters. Notably, the color index analysis (Fig. 23(a, b)) revealed less color changing in PCM-integrated packages, with LHSI packaging yielding optimal results. Moreover, a higher moisture loss rate was observed for the reference case than that observed for both PCM-base packages (Fig. 23(c)). Specifically, mushrooms have lost 79 % of their weight when no PCM is used, compared to 17 %, and 13 % for LHSW, and LHSI cases, respectively. This observation underscores the efficacy of PCMs in regulating temperature and humidity. Additionally, texture analysis indicated that the mushroom softness increases over the storage duration, with LHSB maintaining the highest hardness value at 53.3 %, followed by LHSW at 47.2 %, while LHSI kept the softness at the optimal value at 33.6 % (Fig. 23(d)).

These findings collectively highlight that PCMs have a critical role in the preservation of perishable goods. PCMs have demonstrated
<figure><img src="image_31.png" /><figcaption>Fig. 22. (a) Effect of PCM on meat drip loss [158]. (b) Product temperature during 3 h of power loss test [158]. (c) Photos of products before and after the transport [30].</figcaption></figure>

remarkable efficacy in maintaining consistent temperatures, humidity regulation, and overall quality enhancement of stored products. This improvement in preservation directly contributes to the reduction of food waste, making the integration of PCM a promising technology for enhancing the efficiency and sustainability of the global food supply chain.

## 2.9. Effect on CO₂ emissions

Phase Change Materials have emerged as a promising technology with the potential to indirectly contribute to greenhouse gas reduction. As mentioned in the introduction electricity generation has been identified as the primary sector responsible for generating GHGs. Therefore, by reducing the energy usage of refrigeration systems through installing PCM, we can help mitigate GHG emissions [30,34,50,124]. These GHG reductions are often calculated by multiplying the energy reduced by the electricity emission factor, which is defined by the Intergovernmental Panel on Climate Change as the amount of GHG emitted per unit of electricity generated. It ranges between 578 and 800 kgCO₂·MWh⁻¹ [34,124,177]. Oró et al. [34] have estimated the CO₂ emission reduction achieved through the use of PCMs in the refrigeration sector. The research focused on the European case, considering an emissions factor of 578 kgCO₂ for every MWh consumed. The potential CO₂ reduction obtained by the assessment is represented in Fig. 24(a). Results show that installing PCMs can lead to a decrease in total annual CO₂ emissions

ranging from 15.6 ktCO₂ (low estimation) to 75.4 ktCO₂ (high estimation) corresponding to approximately 5 % to 22 %, respectively.

Chandran et al. [50] conducted a numerical study to assess the energy efficiency, economic benefits, and environmental impacts of incorporating PCMs in a refrigerated vehicle. The model predicted a significant decrease in GHG emissions. Fig. 24 illustrates the annual CO₂ emissions savings for different PCM types and with different masses. It can be seen that the GHG emissions of all PCM types decrease as the PCM mass increases from 45 kg to 105 kg. Among the PCMs evaluated, A28 PCM exhibited the most significant impact, reducing annual emissions from 1818 kg CO₂ to 3060 kg CO₂/year. While the minimum reduction was observed for PT28. Overall, this work highlights the potential of PCM integration to contribute significantly to GHG mitigation in the cold chain transportation sector.

While the benefits of PCMs in reducing electricity consumption are well recognized, further efforts should now focus on the materials used in these PCMs. It is crucial to move beyond petroleum-based products like paraffin and shift towards more sustainable options by exploring bio-based materials. Transitioning to bio-based PCMs offers additional environmental advantages, such as biodegradability and non-flammability. The following section delves into the various bio-based materials that have been identified as promising alternatives for cold thermal energy storage applications.
<figure><img src="image_32.png" /><figcaption>**Fig. 23.** Effect of PCM on mushrooms: (a) color change index; (b) appearance; (c) moisture or weight loss; (d) softness. Adapted from [175].</figcaption></figure>

### 3. Bio-based PCM for cold thermal energy storage system

Non-paraffin PCMs are mostly manufactured from bio-sources materials and used either directly in their raw form or after processing. These materials are classified into two categories: plant and animal sources. Many studies have examined the thermal properties of these materials, focusing primarily on substances from the fatty acids, esters, and sugar alcohols families (Fig. 25). These materials are selected due to their advantageous properties, including biodegradability, less flammability, and non-toxicity [140,141]. This section gives an overview of the bio-based materials that could be employed as PCM for CTES. Table 4 in Appendix D presents a summary of the thermophysical properties, including the melting point and latent heat, of the materials discussed in this review.

In this review, the selection and analysis of materials focus on specific criteria to ensure their suitability for CTES applications, as illustrated in Fig. 26. The selection process was guided by several key criteria, with particular emphasis on bio-based materials as the primary consideration. These materials are further assessed for their compatibility with CTES requirements, particularly their phase change temperature (PCT), ensuring they exhibit low or sub-zero PCTs. Additionally, the latent heat capacity is evaluated for each selected material, this will give a first idea of the material's efficiency of thermal energy storage. Other essential properties, such as non-toxicity, are also considered to ensure safety and practical applicability. This approach aims to identify materials that combine environmental sustainability with optimal thermal performance for CTES applications.

#### 3.1. Fatty acids and esters

Fatty acids (FAs) and esters (also called fatty acid esters, FAEs) are organic materials, commonly derived from vegetable and animal fat [62,178]. FAs are a carboxyl group attached to a long hydrocarbon chain, which is represented by the formula A-COOH (where A is hydrocarbon chain $CH_3(CH_2)_n$) [179,180]. While FAEs are compounds derived by the esterification of FAs with alcohol. See Table 4 Appendix D for details on thermal properties.

Knothe et al. [181] have characterized the melting points of different FAs and FAEs using the differential scanning calorimetry technique (DSC). The analysis showed that the melting temperature of FAEs is appropriate to CTES, as their melting temperature decreases with the carbon atoms number in the carbon chain (Fig. 27(a)). The FAE melting temperature ranges between -45 °C (for the n-octane carbon chain) to -4 °C (for the n-dodecane carbon chain) [181,182]. Ravotti et al. [183] studied the thermal characteristics of five commercial lactone esters. The DSC analysis revealed that among these esters, ε-caprolactone and γ-valerolactone exhibit appropriate melting temperatures for CTES applications. It has been observed that the phase transition for ε-caprolactone and γ-valerolactone starts around -6.9 °C and -40.3 °C, respectively. Further analysis revealed that the melting peaks of these compounds occur at temperatures of -1.5 °C and -32.1 °C, respectively. It is also important to note that the latent heat of these esters was found to be 121.7 J·g⁻¹ and 109.8 J·g⁻¹, respectively, which is lower compared to the latent heat of the salt solution PCMs. Triglycerides are identified as a category of esters, where three FAs are bonded glycerol molecules. Ravotti et al. [184] have reviewed different triglycerides that
<figure><img src="image_33.png" /></figure>

<figure><img src="image_34.png" /><figcaption>Fig. 24. (a) Potential CO₂ reduction in different sectors, Europe scenario, data converted into graph [34]. (b) Annual GHG emissions savings when using different types of PCM, data converted into graph [50].</figcaption></figure>

<figure><img src="image_35.png" /><figcaption>Fig. 25. Different bio-based PCMs reviewed in this paper.</figcaption></figure>

can be employed as PCM in different applications. Among them, three compounds – α-tricaprylin, α-tripelargonin, and α-tricaprin – were the only compounds that characterized a sub-zero melting temperature.

Specifically, the melting points of these materials were reported as –54 °C, –30 °C, and –10 °C, along with corresponding latent heat values of 36 J·g⁻¹, 69.4 J·g⁻¹, and 103 J·g⁻¹ (see Table 4).
<figure><img src="image_36.png" /><figcaption>Fig. 26. Flowchart on framework for selecting materials suitable for cold CTES.</figcaption></figure>

On the other hand, FAs are characterized by a positive melting temperature. This latter depends on the number of carbon within the hydrocarbon chain (as depicted in Fig. 27(a)). It varies from 10 °C to 80 °C for 8 to 24 carbon atoms, respectively. Nevertheless, studies have investigated the properties of fatty acids containing carbon double bonds. These include myristoleic (C14:1 D9c) [181], oleic acid [190], linoleic [191], and linolenic [192]. The melting temperature of these substances was determined to be between -4 °C and -11 °C. Additionally, the latent energy values of these fatty acids were found to be between 45 J·g⁻¹ and 115 J·g⁻¹ (more detailed in Table 4).

## 3.2. Edible and non-edible oils

Vegetable oils are a composition of diverse fatty acids and triglycerides and have been employed as TES in many applications and for different temperature ranges (buildings applications; cold applications) [193–196]. Soybean, canola, and corn oils are characterized by a low melting temperature of -3.53 °C, -20 °C, and -24.6 °C, respectively, making these PCMs appropriate to CTES [197–199]. However, their latent heat is low, 47.4 J·g⁻¹ for soy oil, and 57.5 J·g⁻¹ for canola oil [199,200]. Studies demonstrate that this limitation can be overcome by blending these oils with other substances to create a eutectic PCM with promising thermal properties. Studies show that eutectic mixtures based on these oils show promising thermal properties concerning both melting temperature and latent heat.

Rasta et al. [185–187] found that mixing corn or soy oils with tap water enhances this latter's thermal properties, allowing it to be employed as PCM for cold applications. The experimental results proved that soybean and corn oils act as nucleating agents, promoting quick water crystallization. This leads to a decrease in the supercooling degree by 6 K for 10 % oil (from 7.5 K to 1.1 K). In addition, the DSC analysis – represented in Fig. 27(b) – shows that the melting temperature of the water-oil mixture decreases with oil concentration. For 10 % oil the melting point reaches -7.5 °C and -8 °C for corn and soy oil, respectively. However, for the same oil mass fraction, the latent has decreased

by 42 % and 37 %, corresponding to 171.7 J·g⁻¹, and 185.9 J·g⁻¹ for corn, and soy oil, respectively.

In their work, Lorenzo et al. [188], explored the development of a bio-PCM with a low melting temperature suitable for CTES applications. The PCMs were synthesized by blending canola oil and beeswax in different mass fractions (4 %, 6 %, 8 %, and 10 %). The DSC technique was used to determine the melting temperature and latent heat of the mixture. Results indicated that PCMs exhibited a high latent heat capacity, which increases as a function of the beeswax mass fraction. Specifically, they reported that the 10 % beeswax PCM was characterized by a melting temperature of -13.6 °C. However, no specific details were provided for other PCMs concerning their melting temperatures. However, by analyzing Fig. 27(c) one can see that the melting peak is similar to that of 10 % beeswax.

Coffee ground waste valorization was investigated in a study by Jin Ong et al. [189], where they extracted coffee waste oil (CWO) and used it as a sustainable PCM. The CWO was collected through extraction using three different solvents (acetone (A-CWO), ethanol (E-CWO), and hexane (H-CWO)). The chemical composition analysis showed that the oil contains 60–80 % fatty acids, including oleic acid, octadecanoic acid, and n-hexadecanoic acid, among others. The DSC analysis, presented in Fig. 27(d), revealed that the CWO exhibits melting/freezing at temperatures of 5 °C and -1.5 °C respectively, corresponding to a low latent heat value of 50 J·g⁻¹.

Olive mill waste could be valorized by extracting the olive oil, also known as secondary oil. It is estimated that for every ton of oil recovered, approximately 3 tons of waste are generated, including a solid waste known as pomace and a liquid waste called margins. Pomace wastes contain 5–13 % of oil [201–203], while margins contain 7–11 g·L⁻¹ [204–206]. Because of this significant percentage of oil, this waste could be used as a PCM. The process of melting occurs at temperatures ranging from -4.5 °C to 10.4 °C, while freezing occurs between -11 °C and -8 °C. The enthalpies involved in these processes are measured at 105 J·g⁻¹ for melting and 97 J·g⁻¹ for solidification [207]. In addition, the secondary oil has a low thermal conductivity ranging from 0.15 to 0.17 W·m⁻¹·K⁻¹ [208,209].

Another waste that can be recycled is date seeds that contain 4–13 % oil that can be extracted [210–212]. The amount of oil in date seeds is determined by the kind of date and the extraction process. Ourradi et al. [213], investigated the oil content of eight different dates seed types and reported that it ranges from 6 to 10 %. Date seed oil is characterized by a melting temperature of around -3 °C. However, this oil has a low melting enthalpy, between 60 and 70 J·g⁻¹ [214–216].

## 3.3. Animal wastes

Fatty acids are compounds that can be derived from sources like chicken, pork, and fish wastes, these materials present promising opportunities as PCMs. While various animal wastes can serve as PCMs, our primary interest lies in materials suitable for low-temperature applications. Fish waste oils, in particular, demonstrate notable potential for cold storage, with melting points at -70 °C for salmon oil, -44.3 °C for catfish, and -35 °C for Pollock oil. However, their low melting enthalpies – 40 J·g⁻¹, 75.1 J·g⁻¹, and 35 J·g⁻¹ for salmon, catfish, and Pollock, respectively – limit their effectiveness for energy storage purposes [217–219]. Additional details on the thermal properties of fish waste oils can be found in Table 4 (Appendix D).

Other animal wastes, such as pork and chicken waste, have been investigated as potential PCMs. These materials demonstrate promising thermal characteristics that make them attractive for various thermal management applications. Research has highlighted their effectiveness in systems such as building and photovoltaic temperature regulation [220,221]. Notably, these fatty acid-based PCMs exhibit a PCT typically ranging between 25 °C and 55 °C. Additionally, their melting enthalpies have been reported to fall within a relatively narrow range of 155 J·g⁻¹ to 180 J·g⁻¹ [220–223].
<figure><img src="image_37.png" /></figure>

<figure><img src="image_38.png" /></figure>

<figure><img src="image_39.png" /></figure>

<figure><img src="image_40.png" /><figcaption>Fig. 27. (a) FA and FEA melting point as a function of carbon atom number [181]. (b) DSC results representing the freezing temperature and latent heat of the solution as a function of corn and soy oil concentration, data converted into graph [185–187]. (c) Specific heat capacity of canola oil beeswax mixture, adapted from [188]. (d) DSC analysis of extracted coffee oil [189].</figcaption></figure>

<figure><img src="image_41.png" /></figure>

<figure><img src="image_42.png" /><figcaption>Fig. 28. Thermal properties of glycine solutions. Data converted into graphs (a) [226] and (b) [228].</figcaption></figure>
### 3.4. Amino acid

Glycine, recognized as the smallest and simplest amino acid [224,225], has emerged as a widely studied bio-based phase change material (PCM) due to its unique combination of favorable properties. The material's growing popularity in thermal energy storage applications can be attributed to two key factors: its cost-effectiveness and the remarkably high latent heat exhibited by its aqueous solutions [226]. The thermal properties of glycine solutions have attracted considerable research attention, with multiple studies [226-229] evaluating their characteristics for potential applications in CTES.

Liu et al. [226] studied the glycine-water-based (GW) and glycine-water-graphite-based (GWG) as PCM, with expanded graphene being incorporated to enhance the thermal conductivity of the base GW PCM. As shown in Fig. 28(a), three different glycine concentrations (14 %, 16 %, and 18 %) were investigated, revealing distinct trends in both latent heat and phase transition temperature. The latent heat values exhibited a gradual decrease with increasing glycine concentration, from 246.30 J·g⁻¹ at 14 % glycine to 241.50 J·g⁻¹ at 16 %, and further declining to 233.33 J·g⁻¹ at 18 % concentration. Similarly, the PCT showed a decrease from -5.06 °C at 14 % glycine to -5.12 °C at 16 %, reaching -5.29 °C at 18 % concentration.

On the other hand, the GWG PCM is also characterized by a high

melting/freezing latent heat of 243.8/198.8 J·g⁻¹. While its phase change temperatures were recorded at -5 °C for melting and -14.6 °C for freezing. In addition, the thermal conductivity of the mixture was enhanced by 216 % compared to that of GW-PCM.

Zhan et al. [228] have developed a PCM based on glycine combined with a 1 % sodium chloride (NaCl) solution in varying concentrations to identify an optimal mixture. Among the tested formulations, the 5 % glycine-NaCl solution exhibited superior thermophysical properties, including a PCT of -5.94 °C, and a latent heat of 291.15 J·g⁻¹. Fig. 28-(b) gives an overview of the experimental results. Furthermore, the thermal reliability of the 5 % glycine-NaCl solution was evaluated through 50 thermal cycles. The results indicated minimal degradation, with the PCT decreasing by only 0.78 °C and latent heat by 15.36 J·g⁻¹, confirming its excellent stability and suitability for repeated use.

### 3.5. Polyols

Sugar alcohols, also known as polyols, are organic substances that can naturally be found in fruits and vegetables [230]. These materials are commonly used as sweeteners in food and pharmaceutical production. According to [230], Gerd Hormansdorfer suggested that sugar alcohol be used as PCM for solar energy storage applications [231]. These substances are known for their high melting point temperatures,

<figure><img src="image_43.png" /><figcaption>**Fig. 29.** (a) Freezing point of different sugar alcohols aqueous solutions, data converted into graph [234,235,237]. DSC analysis of sorbitol-water mixture at different sorbitol concentrations: (b) 0.5 wt%, (c) 1.0 wt% and (d) 1.5 wt% [237].</figcaption></figure>
which are between 18 °C (for glycerol) and 200 °C (for inositol). Furthermore, they are characterized by high latent heat values ranging between 159 J·g⁻¹ to 350 J·g⁻¹ [230,232]. However, research has shown that the polyols can decrease the melting temperature of a polyols-water mixture from 0 °C to -114 °C [233], depending on the polyols concentration levels [234,235]. Fig. 29(a) gives an overview of the effect of different polyol concentrations on the water freezing temperature.

Uraji et al. [234] have measured the freezing temperatures of different sugar solutions with different concentrations varying from 30 % to 60 %. The results showed that for sucrose, the freezing point decreased from -2 °C at 30 % concentration to around -13 °C at 60 % concentration. Corn syrup demonstrated a significant freezing point depression, with values ranging from -6 °C at 30 % to -23 °C at 60 %. More freezing temperatures for the rest of the solutions are summarized in Table 4, Appendix D. The study was focused solely on the analysis of freezing points and did not provide any information regarding the latent heat of the solutions.

Mulawarman et al. [236] investigated the thermal properties of the water-glycerol solution and the potential of using it as PCM for low-temperature applications. Glycerol (C₃H₈O₃). The T-history analysis shows that glycerol acts as a nucleating agent and reduces supercooling in water. In addition, the results showed that 10 % and 20 % glycerol decreased the solution freezing point from 0 °C to -5 °C and -10 °C respectively.

Sorbitol aqueous solution was also investigated by Vikram [237], in which thermal properties of deionized water with varying concentrations of sorbitol (0.5, 1, and 1.5 wt%) were examined using DSC. Fig. 29 (b, c, d) displays the experimental results demonstrating that adding sorbitol barley changes the melting point (melting curve). On the other hand, it is noticeable from the exothermic curve (freezing curve) that the PCM exhibits a significant hysteresis effect, thereby expanding its melting temperature range. Furthermore, a careful examination of the freezing peak of the solution reveals a non-monotonic trend, wherein the former decreases upon decreasing concentrations of sorbitol content.

The freezing occurs at temperatures of -15.6 °C, -16.1 °C, and -18.1 °C for 0.5, 1.0, and 1.5 wt% of sorbitol, respectively. However, there was also a decrease in the latent heat by approximately 13 % (269.1 J·g⁻¹), 21 % (244.7 J·g⁻¹), and 23.6 % (236.2 J·g⁻¹).

The aforementioned studies have demonstrated that numerous bio-based materials exhibit a wide phase change temperature range. These bio-based materials can be grouped as follows: **Unsuitable bio-based materials**: such as animal fats and coconut oil, do not have appropriate melting temperatures for cold storage applications, particularly in building-related refrigeration systems. **Suitable bio-based materials**: materials such as corn oil, soy oil, and fatty acids have suitable phase change temperatures for cold storage, but their low latent heat limits their use. On the other hand, esters and α-tricaprin, have both appropriate phase change temperatures and high latent heat, making them promising candidates for CTES. **Eutectic bio-based materials**: combining bio-based materials with other substances like water, salt solution or beeswax can enhance both the phase change temperature and latent heat, resulting in improved thermal properties suitable for CTES applications. Water is a commonly used component in formulating bio-eutectic PCMs. Studies indicate that incorporating bio-based materials into water-based PCMs can enhance their PCT depending on the concentration of the bio-based additives. However, this improvement is accompanied by a reduction in latent heat capacity. As illustrated in Fig. 30, the latent heat of eutectic bio-based PCMs is generally lower than that of pure water. To address this challenge, further research is needed to optimize the composition of these bio-eutectic mixtures, aiming to minimize the loss in latent heat capacity while maintaining or improving the desired thermal properties.

## 3.6. Practical implementation of bio-based PCMs for CTES

Bio-based PCMs have been extensively studied in building applications. However, their use in CTES applications remains underexplored. Therefore, the current literature on this specific topic is quite limited, with only a handful of preliminary studies available [227,238–240].

<figure><img src="image_44.png" /><figcaption>Fig. 30. Latent heat as a function of melting temperature for various bio-based materials [37,181–192,196–210,212–219,223,230,232,234–237], data converted into graph.</figcaption></figure>
These studies primarily focus on the integration of bio-based PCMs into cooler boxes, with a specific emphasis on evaluating their potential to extend the shelf life of perishable food products.

Liu et al. [239] investigated three distinct storage scenarios for strawberries to evaluate the effect of glycine-potassium sorbate-water PCM (designated as 6-PCM5) and water-based PCM on the strawberries quality compared to the reference scenario (Without PCM). In each scenario, the strawberries were stored in a cooler box and exposed to the ambient temperature (15 °C) for 32 h. The results showed that the first scenario involved the use of 6-PCM5 – which exhibits a PCT of approximately –5.78 °C – was capable of maintaining the temperature within the box between 0.45 °C and 3 °C for 22.83 h. This scenario resulted in a minimal weight loss rate of 0.74 % and a rotting rate of 7.69 %, indicating an optimal preservation of fruit quality. The second scenario used ice as the cooling medium, yielding a slightly higher average temperature compared to 6-PCM5. Consequently, this scenario exhibited a higher weight loss rate of 0.88 % and a rotting rate of 17.65 %. This highlighted the limitations of ice-based PCM in maintaining ideal storage conditions. The third scenario, exhibits significant deterioration in strawberries quality, with a weight loss rate of 36.8 % and a rotting rate of 58.14 % after the 32-h storage period.

Liu et al. [240] have also evaluated adding a glycine-expanded-graphite-water mixture (G:EG:W) on the quality of strawberries under room temperature (15 °C). The experimental results showed that after 21 h of storage, the weight loss rates of the strawberries were observed to be 5.92 %, 1.03 %, and 0.01 %, for the reference scenario (without PCM), the scenario using ice as PCM, and the scenario using G:EG:W PCM, respectively. The author also reported that the rotting rate when using G:EG:W PCM was 10.11 % and 65.76 % lower than ice and reference scenarios. Measuring 11.63 %, 21.74 %, and 87.5 %, respectively.

Nicolalde et al. [238] evaluated the potential application of avocado seed oil as a PCM. The authors conducted numerical analyses to evaluate various PCM distribution configurations within an insulated container, comparing the thermal performance of four 75 mL packages against an alternative arrangement consisting of two 75 mL packages plus one 150 mL package. The results indicated that the configuration using four 75 mL packages exhibited superior performance. In assessing the impact of this bio-based PCM on food temperature regulation, the results revealed enhanced cold temperature preservation compared to the control condition. The data showed that the bio-based PCM maintained lower temperatures for longer durations, reaching 12 °C approximately 2 h after the control case. Furthermore, following an 8-storage period, the internal air temperature of the container incorporating the PCM was

observed to be 6 °C lower than the container without PCM. These results suggest promising applications for bio-based PCMs in temperature-controlled storage systems.

The recent research on bio-based PCMs demonstrates promising potential for sustainable food preservation applications, particularly in extending the shelf life of perishable products. Although the number of studies investigating bio-based PCMs for CTES applications remains notably limited, and the implementation of these materials is still in its early stages, the reviewed studies highlight significant improvements in maintaining product quality, with notably reduced weight loss and rotting rates compared to without PCM cases. These findings not only support the feasibility of bio-based PCMs but also indicate their potential role in advancing sustainable cold chain solutions.

### 3.7. Life Cycle Assessment

Life Cycle Assessment (LCA) is a widely recognized method for evaluating the environmental impact of materials and products across their entire lifecycle, from production to end-of-life, as shown in Fig. 31 [241]. This methodology considers multiple factors such as human health, greenhouse gas emissions, energy consumption, etc. to assess a product's overall sustainability [144]. Applications of bio-based PCMs remain in the early stages for CTES. As a result, the environmental impacts of bio-based PCMs are challenging to evaluate due to the limited number of LCA studies available [62]. Existing research predominantly focuses on the use of bio-based PCMs in building applications [62,144]. These studies demonstrate that incorporating PCMs in construction can offer more ecological benefits compared to conventional insulation materials [144]. However, the environmental footprint of PCMs varies significantly depending on their type.

For instance, Fabiani et al. [242] reported that raw palm oil has a higher carbon footprint (2.772 kg CO₂-eq) compared to paraffin (0.207 kg CO₂-eq). Conversely, palm oil waste is more sustainable, with lower emissions (0.053 kg CO₂-eq). Another study [243] compared the environmental impact of used cooking oil-based PCMs (UCO-PCM) to commercial paraffin and found that UCO-PCM had a higher environmental impact. This was attributed to its lower latent heat, which requires larger quantities of UCO-PCM to achieve the same heat storage capacity as paraffin, consequently increasing encapsulation material requirements and overall environmental impact.

Nöel et al. [244] highlighted potential reductions of GHG emissions of dodecanoic fatty acid derived from palm oil for use in a domestic solar water heater. The study concluded that bio-based PCMs are a viable energy-saving solution, with a payback period of less than two years,

<figure><img src="image_45.png" /><figcaption>Fig. 31. Life cycle of a PCM product [246].</figcaption></figure>
and a potential greenhouse gas emission reduction of approximately 1600 kg CO₂ annually for a typical American home. However, environmental considerations must account for associated challenges like potential deforestation in palm oil production.

A comparative study by Menoufi et al. [245] evaluated the environmental impact of esters as PCMs compared to paraffin and hydrated salts. The analysis included scenarios using polyurethane foam alone, foam combined with PCM, and a reference case without PCM or foam. The results showed that adding polyurethane foam increased the environmental impact by 20 %. Incorporating PCMs into the foam led to environmental score increases of 6.1 %, 7.7 %, and 18.5 % for esters, hydrated salts, and paraffin, respectively. However, using esters and hydrated salts resulted in 10.5 % and 9.1 % lower impacts, respectively, compared to paraffin.

These studies emphasize the need for more comprehensive LCA studies particularly exploring bio-based PCM applications for CTES applications, to better understand their environmental trade-offs and optimize their sustainability.

## 4. Conclusion

The integration of conventional PCMs in refrigeration systems has proven to be a promising approach to improving energy efficiency and environmental sustainability. This review has demonstrated that PCMs can be effectively incorporated into various refrigeration applications, ranging from domestic refrigerators to industrial cold storage facilities, through two main strategies: thermal insulation and cold energy storage systems. As a thermal insulation method, PCMs effectively reduce heat transfer through system walls, thereby decreasing the energy consumption required to maintain desired temperatures. The cold energy storage approach uses PCMs to store excess cooling capacity for later use, offering benefits during compressor off-cycles, door openings, defrosting, or power outages. Moreover, this method enables innovative energy management strategies, such as storing cold energy during low-cost electricity periods and utilizing alternative energy sources like photovoltaic power for PCM charging. The effectiveness of PCM integration critically depends on material selection, placement, and orientation. For example, placing PCMs near evaporator fans facilitates natural convection and promotes more uniform temperature distribution. Conversely, improper positioning can negatively impact air circulation and overall system efficiency.

Bio-based PCMs, derived from renewable plant and animal sources, have gained significant attention as eco-friendly and cost-effective alternatives to petroleum-based options. These materials offer a wide range of phase change temperatures, from temperatures suitable for building applications to low/subzero temperatures appropriate for CTES. However, some biomaterials are characterized by low latent heat capacity, which constrains their use. To address this challenge, researchers have investigated bio-eutectic compounds, which combine bio-based materials with supplementary substances, including water, salt solutions, or beeswax. These hybrid systems effectively enhance both phase change temperature and latent heat capacity, thereby optimizing PCM performance for CTES applications. Preliminary studies on bio-based PCM applications have demonstrated their capacity to provide sustained cold energy and maintain stable air temperatures, suggesting potential benefits for preserving product quality during storage, particularly for temperature-sensitive perishable goods.

While the current review highlights the promising thermal characteristics of bio-based materials for CTES, several critical research directions merit further investigation to advance the field:

- Performance evaluation of bio-based PCMs: future research should comprehensively assess the potential of bio-based PCMs in CTES. Beyond current applications in cooler boxes and product preservation, systematic studies are needed to evaluate their impact on

energy consumption and overall system performance. Comparative analyses with conventional refrigeration technologies would provide valuable insights into the practical viability of these sustainable alternatives.

- Optimization of thermal properties: continued optimization of thermal characteristics remains crucial. Researchers should concentrate on improving key parameters such as melting temperature, latent heat capacity, and thermal conductivity. These enhancements are essential to meet the specific and demanding requirements for CTES applications.

- Advanced encapsulation techniques: research should explore innovative encapsulation methods, such as microencapsulation and nanoencapsulation. These methods can potentially improve heat transfer capabilities and thermal conductivity, thereby addressing the current performance limitations of bio-based PCMs.

- Eutectic/hybrid material: investigating eutectic/hybrid mixtures of bio-based PCMs is another point that needs to be explored. This also could overcome the limitations associated with low latent heat capacity while optimizing their phase change characteristics.

- Sustainability assessment: a comprehensive lifecycle analysis is important to fully understand the environmental impacts of bio-based PCMs. Future studies should conduct rigorous evaluations of the ecological footprint throughout the production, utilization, and disposal phases. This research will provide critical insights into the sustainability advantages of bio-based alternatives compared to conventional PCMs.

Addressing these areas, the development and adoption of bio-based PCMs can significantly contribute to a sustainable, high-performance, and cost-effective solution to advance the field of cold thermal energy storage.

### CRediT authorship contribution statement

**Zakaria Ouaouja:** Writing – original draft, Visualization, Resources, Investigation.
**Abdellah Ousegui:** Writing – review & editing, Supervision, Resources, Investigation.
**Cyril Toublanc:** Writing – review & editing, Supervision, Resources, Investigation.
**Olivier Rouaud:** Writing – review & editing, Supervision, Resources, Investigation.
**Michel Havet:** Writing – review & editing, Supervision, Resources, Investigation.

### Declaration of generative AI and AI-assisted technologies in the writing process

During the preparation of this work, the authors used AI language models to enhance the manuscript's readability and language following the initial draft. The authors carefully reviewed and edited the AI-assisted content, ensuring its accuracy and appropriateness. The authors assume full responsibility for the final published article and its contents.

### Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

### Acknowledgement

This work represents a collaboration between the GEPEA Laboratory at Oniris, Nantes, France, and RIPA at Université Moulay Ismail, Meknes, Morocco. The authors extend their sincere gratitude to the "Partenariat Hubert Curien (PHC) TOUBKAL 2022" for their financial support.
Appendix A

<table><caption>**Table 1**
Effect of additives on thermal properties of phase change materials.</caption><thead><tr><th>Technique</th><th>Additive</th><th>PCM</th><th>Results</th><th>Reference</th><th>Year</th></tr></thead><tbody><tr><td rowspan="10">Nano-additive</td><td rowspan="3">Copper oxide (CuO)</td><td>Coconut oil</td><td>- Mass fraction equal to 0.1 % and 1 %.<br/>- Enhanced the thermal conductivity by 4.8 % and 7.5 % for CuO mass fraction, respectively.<br/>- Decreased the latent heat by 1.94 % and 8.25 %.</td><td>[78]</td><td>2018</td></tr><tr><td>Palmitic acid</td><td>- Adding 0.1–0.3 wt% of CuO, can improve thermal conductivity by 20–66 %.<br/>- While reducing latent heat by 0.6–2.4 %.</td><td>[79]</td><td>2018</td></tr><tr><td>Glycerol &amp; water</td><td>- CuO nanoparticles improved the thermal conductivity compared to pure PCM by 5.3 % and 40.2 % for 0.1 wt% and 1 wt%, respectively.<br/>- While for the same mass fraction as above, the latent heats of the mixtures were slightly reduced by 0.2 % and 1.57 %.</td><td>[80]</td><td>2013</td></tr><tr><td rowspan="5">Titanium dioxide (TiO<sub>2</sub>)</td><td>Ethylene glycol &amp; water</td><td>- 0.1–0.4 wt% of nanoparticles were added to ethylene glycol water with a 12 % concentration of EG.<br/>- The thermal conductivity was enhanced by 2–7 % for solid state, and by 1–3 % for liquid state.<br/>- However, latent heat was reduced by 0–6.4 % for the mixture.</td><td>[77]</td><td>2017</td></tr><tr><td>Salt hydrates (BaCl<sub>2</sub> 2H<sub>2</sub>O)</td><td>- The thermal conductivity for both solid and liquid phases was increased by 13 % and 17 % respectively.<br/>- Latent heat and specific heat were reduced by 8 % and 12 %.</td><td>[102]</td><td>2012</td></tr><tr><td>Paraffin</td><td>- Adding 0.5 wt% of TiO<sub>2</sub> improved the thermal conductivity by 138 %.<br/>- 68 % of the latent heat capacity was lost.</td><td>[108]</td><td>2020</td></tr><tr><td>Ester</td><td>- 0.1–1.5 wt% enhanced the thermal conductivity by 11.3–110.7 %.<br/>- The melting/solidification time was reduced by 8.5 % and 23.9 %.<br/>- On the other hand, the mean latent heat capacity was reduced by 1.4–7.7 %</td><td>[103]</td><td>2014</td></tr><tr><td>Aluminum oxide (Al<sub>2</sub>O<sub>3</sub>)</td><td>Glycol &amp; water</td><td>- For 0.05–0.2 wt% of Al<sub>2</sub>O<sub>3</sub>, the thermal conductivity is increased by 7.9–10.5 %.<br/>- The supercooling of the PCM was reduced by 2.8–5.6 K.<br/>- The freezing time was reduced by 6.7–23.3 %.</td><td>[104]</td><td>2009</td></tr><tr><td rowspan="2">Magnesium oxide (MgO)</td><td>Salt hydrates (BaCl<sub>2</sub>2H<sub>2</sub>O)</td><td>For 0.2–1 wt% of MgO.<br/>- The thermal conductivity is enhanced by 11–18 %<br/>- Decreased the latent heat by 1–7 %</td><td>[107]</td><td>2018</td></tr><tr><td>Salt hydrates (BaCl<sub>2</sub> 2H<sub>2</sub>O)</td><td>For 0.2–1 wt% of CNT<br/>- The thermal conductivity was enhanced by 1–6 %.<br/>- The latent heat capacity decreased by 2.5–12.3 %.</td><td>[107]</td><td>2018</td></tr><tr><td rowspan="7">Carbon nanotubes (CNT)</td><td>Palmitic-stearic</td><td>- The thermal conductivity was higher than that of pure PCM by 20.2–29.7 % for 5–8 wt %.<br/>- Whereas, latent heat was 5.3 %–8.3 % lower.</td><td>[83]</td><td>2014</td></tr><tr><td>Salt hydrates (MgCl<sub>2</sub>H<sub>2</sub>O)</td><td>- 0.5–3 wt% of CNT enhanced thermal conductivity by 2.6–10.6 %.<br/>- While latent heat was decreased by 2.9–8.8 %.</td><td>[105]</td><td>2020</td></tr><tr><td>Bio-based PCM</td><td>- 1–5 wt% of CNT increased the thermal conductivity by 166–248 %.<br/>- However, reduced the latent heat by 6–9.1 %.</td><td>[81]</td><td>2014</td></tr><tr><td>Palmitic acid</td><td>- Adding 0.2–1 wt% of CNT increased the PCM thermal conductivity by 4–47 %.<br/>- The latent heat decreases by 3.7–11.5 % for 0.2–1 wt% of CNT, respectively.</td><td>[82]</td><td>2010</td></tr><tr><td>Ethylene glycol</td><td>- 1 wt% of xGO has reduced the supercooling by 11.72 °C (62.7 %) compared to the pure EG.</td><td>[106]</td><td>2018</td></tr><tr><td>Coconut oil</td><td>- The thermal conductivity of coconut oil and palm oil increased by 414 % and 437 %, respectively.<br/>- However, the latent heat capacity decreased by 25 % for coconut oil and 38 % for palm oil.</td><td>[84]</td><td>2015</td></tr><tr><td>Palm oil</td><td>- 1–5 wt% of GnP increased the thermal conductivity by 78–336 %.<br/>- On the other hand, the latent heat was decreased by 1.8–6.6 % for the same additive concentration.</td><td>[81]</td><td>2014</td></tr><tr><td rowspan="2">Graphene oxide (GO)</td><td>Bio-based PCM</td><td>- The thermal conductivity of GnP-water was increased as a function of GnP concentration.</td><td>[85]</td><td>2019</td></tr><tr><td>Water</td><td>- For 0.1–0.5, the thermal conductivity of the liquid state was 11–24 % greater than the reference PCM. While, for the solid state, the thermal conductivity was 19.6–53.9 % greater when using GnP.<br/>- The melting time was reduced by 8.3–41.7 %.</td><td></td><td></td></tr><tr><td rowspan="2">Nucleate agent</td><td>Soy oil; corn oil</td><td>Water</td><td>- Soybean and corn oil act as a nucleating agent and reduce water supercooling by 6 K.<br/>- 5, 7.5 and 10 % of soybean oil drop the water freezing temperature by 4 °C, 5 °C and 6.5 °C respectively, and by 3.5 °C, 5 °C and 6.5 °C respectively for the corn oil.</td><td>[185–187]</td><td>2016<br/>2018<br/>2019</td></tr><tr><td>Propylene glycol</td><td>Water</td><td>The supercooling degree of water decreased as the agent concentration increased. It dropped from 7.5 K to 7 K, 3.5 K, and 1.5 K for mixtures with 10, 20, and 30 % of PG, respectively.<br/>- The melting point of water dropped to –4.5, –12, and –17 °C with 10, 20, and 30 % of PG, respectively.</td><td>[236]</td><td>2018</td></tr><tr><td>Thickening agent</td><td>Sodium alginate</td><td>Salt hydrates</td><td>- Reduces the degree of supercooling as well as the phase separation.<br/>- Reduces latent heat by 62 %, 64.6 %, and 75.3 % using 1, 3, and 5 wt% of SA respectively.</td><td>[100]</td><td>2018</td></tr></tbody></table>

(continued on next page)
<table><caption>**Table 1 (continued)**</caption><thead><tr><th>Technique</th><th>Additive</th><th>PCM</th><th>Results</th><th>Reference</th><th>Year</th></tr></thead><tbody><tr><td rowspan="10">Porous material</td><td>Aluminum foam</td><td>Paraffin</td><td>– Aluminum matrices with 95 % and 77 % porosity, can enhance the thermal conductivity by 1500–6800 %.</td><td>[90]</td><td>2016</td></tr><tr><td rowspan="2">Nickel foams</td><td>Paraffin</td><td>– The thermal conductivity increased by 250 % to 560 %.</td><td>[91]</td><td>2014</td></tr><tr><td>Myristyl alcohol</td><td>– The thermal conductivity was 180 % higher than pure PCM when using nickel foam as support material.</td><td>[92]</td><td>2017</td></tr><tr><td rowspan="3">Copper foams</td><td>Paraffin</td><td>– However, the latent heat was reduced by 6 %</td><td>[91]</td><td>2014</td></tr><tr><td>Myristyl alcohol</td><td>– Copper foam enhanced the thermal conductivity of paraffin by 130 % to 440 %.</td><td>[92]</td><td>2017</td></tr><tr><td>Palmitic acid</td><td>– Myristyl alcohol thermal conductivity was improved by approximately 750 %. – While the latent heat capacity was decreased by 8 %.</td><td>[93]</td><td>2021</td></tr><tr><td rowspan="3">Graphite foam</td><td>Paraffin</td><td>– Improves the thermal conductivity of palmitic acid by 1760 % and decreases the latent heat of fusion by 7 %.</td><td>[94]</td><td>2016</td></tr><tr><td>Erythritol</td><td>– Increased the thermal conductivity from 0.3 to 10.1 W·m<sup>-1</sup>·K<sup>-1</sup>, 3260 % higher than pure paraffin. – The latent heat was reduced by 32 %.</td><td>[88]</td><td>2021</td></tr><tr><td>Hydrated salts (Ba(OH)<sub>2</sub> 8H<sub>2</sub>O)</td><td>– Thermal conductivity was 5400–9300 % higher when using graphite foam. – The latent heat was decreased by 19–45 %. – Phase segregation was eliminated. – Thermal conductivity increased by 184 %. – Latent heat of melting and freezing were reduced by 7.8 % and 3.6 %, respectively.</td><td>[89]</td><td>2018</td></tr></tbody></table>

## Appendix B

<table><caption>**Table 2**
Commercially available phase change materials for cold storage applications.</caption><thead><tr><th rowspan="2">Material</th><th rowspan="2">Company</th><th rowspan="2">Type</th><th>Phase change temperature</th><th>Latent heat</th><th>Thermal conductivity</th><th>Cost</th><th rowspan="2">Reference</th></tr><tr><th>°C</th><th>J·g<sup>-1</sup> (liquid/solid)</th><th>W·m<sup>-1</sup>·K<sup>-1</sup> (liquid/solid)</th><th>€/kg</th></tr></thead><tbody><tr><td>E-114</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-114</td><td>107</td><td>–</td><td>–</td><td>[59]</td></tr><tr><td>E-90</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-90</td><td>90</td><td>–</td><td>–</td><td>[59]</td></tr><tr><td>E-78</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-78</td><td>115</td><td>–</td><td>–</td><td>[59]</td></tr><tr><td>HS 75N</td><td>savE-Pluss</td><td>Hydrated salts</td><td>-75/-80</td><td>209</td><td>0.6 (liquid)</td><td>52</td><td>[51]</td></tr><tr><td>E-74</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-74</td><td>230</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>E-70</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-70</td><td>200</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>-67G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-67</td><td>140</td><td>–</td><td>–</td><td>[134]</td></tr><tr><td>E-65</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-65</td><td>240</td><td>0.56</td><td>–</td><td>[59]</td></tr><tr><td>HS65N</td><td>savE-Pluss</td><td>Hydrated salts</td><td>-65/-75</td><td>171.76</td><td>0.5</td><td>64</td><td>[51]</td></tr><tr><td>ATS-63</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-63</td><td>190</td><td>0.6</td><td>3–15</td><td>[60]</td></tr><tr><td>E-62</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-62</td><td>180</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>E-60</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-60</td><td>172</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>E-55</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-55</td><td>223</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>ATS-50</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-50</td><td>220</td><td>0.6</td><td>–</td><td>[60]</td></tr><tr><td>E-50</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-50</td><td>175</td><td>0.56</td><td>–</td><td>[59]</td></tr><tr><td>SP-50</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-50</td><td>190</td><td>0.6</td><td>5–15</td><td>[58]</td></tr><tr><td>PCM-(-50)</td><td>TEAP PCM</td><td>Hydrated salts</td><td>-50</td><td>325</td><td>–</td><td>–</td><td>[133]</td></tr><tr><td>-50G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-50</td><td>170</td><td>–</td><td>–</td><td>[134]</td></tr><tr><td>E-48</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-48</td><td>202</td><td>0.56</td><td>–</td><td>[59]</td></tr><tr><td>ATS-40</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-40</td><td>180</td><td>0.6</td><td>–</td><td>[60]</td></tr><tr><td>E-37</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-37</td><td>225</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>-37G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-37</td><td>213</td><td>–</td><td>–</td><td>[134]</td></tr><tr><td>PureTemp-37</td><td>PureTemp LLC</td><td>Bio-based</td><td>-37</td><td>145</td><td>0.15/0.25</td><td>6–10</td><td>[61]</td></tr><tr><td>ATS-34</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-34</td><td>240</td><td>0.6</td><td>–</td><td>[60]</td></tr><tr><td>E-34</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-34</td><td>200</td><td>0.54</td><td>–</td><td>[59]</td></tr><tr><td>SN 33</td><td>Thermofin</td><td>Hydrated salts</td><td>-33</td><td>245</td><td>–</td><td>–</td><td>[131]</td></tr><tr><td>E-32</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-32</td><td>225</td><td>0.56</td><td>–</td><td>[59]</td></tr><tr><td>-32G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-32</td><td>243</td><td>–</td><td>–</td><td>[134]</td></tr><tr><td>PCM-30</td><td>Microteklabs</td><td>Paraffin</td><td>-30</td><td>155</td><td>0.140</td><td>120.4</td><td>[132]</td></tr><tr><td>HS30N</td><td>savE-Pluss</td><td>Hydrated salts</td><td>-30/-31</td><td>197/201</td><td>–</td><td>8</td><td>[51]</td></tr><tr><td>SN 29</td><td>Thermofin</td><td>Hydrated salts</td><td>-29</td><td>233</td><td>–</td><td>–</td><td>[131]</td></tr><tr><td>E-29</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-29</td><td>250</td><td>0.64</td><td>–</td><td>[59]</td></tr><tr><td>SP-30</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-28.5</td><td>250</td><td>0.6</td><td>5–15</td><td>[58]</td></tr><tr><td>SP-28</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-28.5</td><td>260</td><td>0.6</td><td>5–15</td><td>[58]</td></tr><tr><td>SN 26</td><td>Thermofin</td><td>Hydrated salts</td><td>-26</td><td>268</td><td>–</td><td>–</td><td>[131]</td></tr><tr><td>E-26</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-26</td><td>265</td><td>0.58</td><td>–</td><td>[59]</td></tr><tr><td>HS26N</td><td>savE-Pluss</td><td>Hydrated salts</td><td>-26</td><td>264/182</td><td>–</td><td>1.7</td><td>[51]</td></tr><tr><td>PCM-HS26N</td><td>saveENRG PCM</td><td>Hydrated salts</td><td>-26</td><td>264/182</td><td>–</td><td>–</td><td>[247]</td></tr><tr><td>-26G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-26</td><td>200</td><td>–</td><td>–</td><td>[134]</td></tr><tr><td>BioPCM-25</td><td>Phase Change Solutions</td><td>Bio-based</td><td>-25</td><td>200</td><td>–</td><td>–</td><td>[135]</td></tr><tr><td>ATS-24</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-24</td><td>340</td><td>0.6</td><td>–</td><td>[60]</td></tr><tr><td>HS23N</td><td>savE-Pluss</td><td>Hydrated salts</td><td>-22/-23</td><td>274/261</td><td>0.702/4.976</td><td>1.3</td><td>[51]</td></tr><tr><td>PCM-(-23)</td><td>TEAP PCM</td><td>Hydrated salts</td><td>-23</td><td>330</td><td>–</td><td>–</td><td>[133]</td></tr></tbody></table>

(continued on next page)
<table><caption>Table 2 (continued)</caption><thead><tr><th rowspan="2">Material</th><th rowspan="2">Company</th><th rowspan="2">Type</th><th>Phase change temperature</th><th>Latent heat</th><th>Thermal conductivity</th><th>Cost</th><th rowspan="2">Reference</th></tr><tr><th>°C</th><th>J·g<sup>-1</sup> (liquid/solid)</th><th>W·m<sup>-1</sup>·K<sup>-1</sup> (liquid/solid)</th><th>€/kg</th></tr></thead><tbody><tr><td>ClimSel C-21</td><td>Climator</td><td>Hydrated salts</td><td>-22.5</td><td>283</td><td>0.42/2.01</td><td>-</td><td>[130]</td></tr><tr><td>SP-24</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-22.5</td><td>250</td><td>0.6</td><td>5-15</td><td>[58]</td></tr><tr><td>ATS-24</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-24</td><td>340</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>E-22</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-22</td><td>305</td><td>0.57</td><td>-</td><td>[59]</td></tr><tr><td>BioPCM-22</td><td>Phase Change Solutions</td><td>Bio-based</td><td>-22</td><td>200</td><td>-</td><td>-</td><td>[135]</td></tr><tr><td>ATS-21</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-21</td><td>320</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>SN 21</td><td>Thermofin</td><td>Hydrated salts</td><td>-21</td><td>240</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>E-21</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-21</td><td>285</td><td>0.51</td><td>-</td><td>[59]</td></tr><tr><td>PC-21</td><td>PCPAustralia</td><td>Hydrated salts</td><td>-21</td><td>222</td><td>-</td><td>-</td><td>[137]</td></tr><tr><td>PC-21</td><td>Thermal custom packaging</td><td>Hydrated salts</td><td>-21</td><td>222</td><td>-</td><td>-</td><td>[136]</td></tr><tr><td>-21G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-21</td><td>234</td><td>-</td><td>-</td><td>[134]</td></tr><tr><td>PureTemp-21</td><td>PureTemp LLC</td><td>Bio-based</td><td>-21</td><td>239</td><td>0.55/2.39</td><td>6-10</td><td>[61]</td></tr><tr><td>PCM-21B</td><td>Temprecision PCM</td><td>Hydrated salts</td><td>-24/-21</td><td>308</td><td>-</td><td>-</td><td>[248]</td></tr><tr><td>ClimSel C-18</td><td>Climator</td><td>Hydrated salts</td><td>-20.5</td><td>283</td><td>0.3/1.86</td><td>-</td><td>[130]</td></tr><tr><td>SP-21</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-20</td><td>285</td><td>0.6</td><td>5-15</td><td>[58]</td></tr><tr><td>HS21N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-21/-23</td><td>254</td><td>0.7 (liquid)</td><td>1.4</td><td>[135]</td></tr><tr><td>E-19</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-19</td><td>300</td><td>0.58</td><td>-</td><td>[59]</td></tr><tr><td>BioPCM-18</td><td>Phase Change Solutions</td><td>Bio-based</td><td>-18</td><td>200</td><td>-</td><td>-</td><td>[135]</td></tr><tr><td>HS18N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-18</td><td>260/290</td><td>0.44 (liquid)</td><td>2.7</td><td>[51]</td></tr><tr><td>SN 18</td><td>Thermofin</td><td>Hydrated salts</td><td>-17.5</td><td>268</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>SP-17</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-17.5</td><td>300</td><td>0.6</td><td>5-15</td><td>[58]</td></tr><tr><td>PC-16</td><td>PCPAustralia</td><td>Hydrated salts</td><td>-16</td><td>289</td><td>-</td><td>-</td><td>[137]</td></tr><tr><td>PCM-(-16)</td><td>TEAP PCM</td><td>Hydrated salts</td><td>-16</td><td>330</td><td>-</td><td>-</td><td>[133]</td></tr><tr><td>PC-16</td><td>Thermal custom packaging</td><td>Hydrated salts</td><td>-16</td><td>289</td><td>-</td><td>-</td><td>[136]</td></tr><tr><td>AN 15</td><td>Thermofin</td><td>Hydrated salts</td><td>-15.44</td><td>311</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>E-15</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-15</td><td>320</td><td>0.53</td><td>-</td><td>[59]</td></tr><tr><td>BioPCM-15</td><td>Phase Change Solutions</td><td>Bio-based</td><td>-15</td><td>200</td><td>-</td><td>-</td><td>[135]</td></tr><tr><td>HS15N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-16/-17</td><td>327/341</td><td>0.53/5.26</td><td>2</td><td>[51]</td></tr><tr><td>-15G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-15</td><td>300</td><td>-</td><td>-</td><td>[134]</td></tr><tr><td>PureTemp-15</td><td>PureTemp LLC</td><td>Bio-based</td><td>-15</td><td>301</td><td>0.55/2.34</td><td>6-10</td><td>[61]</td></tr><tr><td>ATS-12</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-12</td><td>360</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>E-11</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-12</td><td>310</td><td>0.57</td><td>-</td><td>[59]</td></tr><tr><td>AN 12</td><td>Thermofin</td><td>Hydrated salts</td><td>-11.72</td><td>306</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>SP-11</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-11.5</td><td>290</td><td>0.6</td><td>5-15</td><td>[58]</td></tr><tr><td>PC-11</td><td>PCPAustralia</td><td>Hydrated salts</td><td>-11</td><td>283</td><td>-</td><td>-</td><td>[137]</td></tr><tr><td>Parafol 12-97</td><td>Sasol Inc.</td><td>Paraffin</td><td>-10.5</td><td>210</td><td>-</td><td>-</td><td>[249]</td></tr><tr><td>AN 10</td><td>Thermofin</td><td>Hydrated salts</td><td>-10.41</td><td>310</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>PCM-10B</td><td>Temprecision PCM</td><td>Hydrated salts</td><td>-12/-10</td><td>3500</td><td>-</td><td>-</td><td>[248]</td></tr><tr><td>ATS-10</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-10</td><td>345</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>PCM-10</td><td>Microteklabs</td><td>Paraffin</td><td>-10</td><td>180</td><td>0.140</td><td>120.4</td><td>[132]</td></tr><tr><td>PCM-HS10N</td><td>saveENRG PCM</td><td>Hydrated salts</td><td>-10/-11</td><td>330/3333</td><td>0.6/4.25</td><td>-</td><td>[247]</td></tr><tr><td>HS10N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-10/-11</td><td>330/333</td><td>0.6/4.25</td><td>2</td><td>[51]</td></tr><tr><td>Tetradecane</td><td>Sasol Inc.</td><td>Paraffin</td><td>-9.8</td><td>265.4</td><td>-</td><td>-</td><td>[52]</td></tr><tr><td>RT-9HC</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-9</td><td>250</td><td>0.2</td><td>5-15</td><td>[58]</td></tr><tr><td>PC-7</td><td>PCPAustralia</td><td>Hydrated salts</td><td>-7</td><td>290</td><td>2.1 (Solid)</td><td>-</td><td>[137]</td></tr><tr><td>HS7N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-7</td><td>296</td><td>-</td><td>-</td><td>[51]</td></tr><tr><td>PC-7</td><td>Thermal custom packaging</td><td>Hydrated salts</td><td>-7</td><td>290</td><td>2.7 (Solid)</td><td>-</td><td>[136]</td></tr><tr><td>ATS-6</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-6</td><td>360</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>E-6</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-6</td><td>300</td><td>0.56</td><td>-</td><td>[59]</td></tr><tr><td>SP-7</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-6</td><td>290</td><td>0.6</td><td>5-15</td><td>[58]</td></tr><tr><td>SP-5</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-6</td><td>320</td><td>0.2</td><td>5-15</td><td>[58]</td></tr><tr><td>AN 06</td><td>Thermofin</td><td>Hydrated salts</td><td>-5.5</td><td>284</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>E-3</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-4</td><td>330</td><td>0.6</td><td>-</td><td>[59]</td></tr><tr><td>RT-4</td><td>Rubitherm GmbH</td><td>Hydrated salts</td><td>-4</td><td>180</td><td>0.2</td><td>5-15</td><td>[58]</td></tr><tr><td>ATS-3</td><td>Axiotherm GmbH</td><td>Hydrated salts</td><td>-3</td><td>330</td><td>0.6</td><td>-</td><td>[60]</td></tr><tr><td>HS3N</td><td>save-Pluss</td><td>Hydrated salts</td><td>-2/-3</td><td>359/329</td><td>0.35/2.2</td><td>1.7</td><td>[51]</td></tr><tr><td>-03G</td><td>Va-Q-Tec</td><td>Hydrated salts</td><td>-3</td><td>240</td><td>-</td><td>-</td><td>[134]</td></tr><tr><td>AN 03</td><td>Thermofin</td><td>Hydrated salts</td><td>-2.6</td><td>328</td><td>-</td><td>-</td><td>[131]</td></tr><tr><td>E-2</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>-2</td><td>325</td><td>0.58</td><td>-</td><td>[59]</td></tr><tr><td>E0</td><td>PCM Products Limited</td><td>Hydrated salts</td><td>0</td><td>395</td><td>0.58</td><td>-</td><td>[59]</td></tr><tr><td>PC0</td><td>PCPAustralia</td><td>Hydrated salts</td><td>0</td><td>333</td><td>0.5/1</td><td>-</td><td>[137]</td></tr><tr><td>HS01</td><td>save-Pluss</td><td>Hydrated salts</td><td>0</td><td>359/364</td><td>0.55/2.2</td><td>0.4</td><td>[51]</td></tr><tr><td>ClimSel CZ</td><td>Climator</td><td>Hydrated salts</td><td>0</td><td>393</td><td>1.6/1.95</td><td>-</td><td>[130]</td></tr><tr><td>PC0</td><td>Thermal custom packaging</td><td>Hydrated salts</td><td>0</td><td>333</td><td>0.5/1</td><td>-</td><td>[136]</td></tr><tr><td>ATP 2</td><td>Axiotherm GmbH</td><td>Organic</td><td>2</td><td>215</td><td>0.2</td><td>-</td><td>[60]</td></tr><tr><td>A2</td><td>PCM Products Limited</td><td>Organic</td><td>2</td><td>230</td><td>0.21</td><td>-</td><td>[59]</td></tr><tr><td>Dodecane</td><td>Sasol Inc.</td><td>Paraffin</td><td>3.4</td><td>216</td><td>-</td><td>-</td><td>[52]</td></tr><tr><td>A3</td><td>PCM Products Limited</td><td>Organic</td><td>3</td><td>230</td><td>0.21</td><td>-</td><td>[59]</td></tr><tr><td>FS03</td><td>save-Pluss</td><td>-</td><td>3</td><td>214/217</td><td>0.15 (solid)</td><td>-</td><td>[51]</td></tr><tr><td>OM03</td><td>save-Pluss</td><td>Bio-based</td><td>5/3</td><td>196/228</td><td>0.146/0.224</td><td>-9.3</td><td>[51]</td></tr><tr><td>ATP 4</td><td>Axiotherm GmbH</td><td>Organic</td><td>4</td><td>260</td><td>0.2</td><td>-</td><td>[60]</td></tr><tr><td>A4</td><td>PCM Products Limited</td><td>Organic</td><td>4</td><td>235</td><td>0.21</td><td>-</td><td>[59]</td></tr><tr><td>BioPCM 4</td><td>Phase Change Solutions</td><td>Bio-based</td><td>4</td><td>210</td><td>-</td><td>-</td><td>[135]</td></tr><tr><td>PCM-(-4)</td><td>TEAP PCM</td><td>Hydrated salts</td><td>4</td><td>105</td><td>-</td><td>-</td><td>[133]</td></tr></tbody></table>

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<table><caption>**Table 2 (continued)**</caption><thead><tr><th rowspan="2">Material</th><th rowspan="2">Company</th><th rowspan="2">Type</th><th>Phase change temperature</th><th>Latent heat</th><th>Thermal conductivity</th><th>Cost</th><th rowspan="2">Reference</th></tr><tr><th>°C</th><th>J·g<sup>-1</sup> (liquid/solid)</th><th>W·m<sup>-1</sup>·K<sup>-1</sup> (liquid/solid)</th><th>€/kg</th></tr></thead><tbody><tr><td>PureTemp 4</td><td>PureTemp LLC</td><td>Bio-based</td><td>4</td><td>187</td><td>0.15/0.25</td><td>6–10</td><td>[61]</td></tr><tr><td>Parafol 14-97</td><td>Sasol Inc.</td><td>Parrafin</td><td>4</td><td>210</td><td>–</td><td>–</td><td>[249]</td></tr><tr><td>PCM+5A</td><td>Temprecision PCM</td><td>Hydrated salts</td><td>4/6</td><td>242</td><td>–</td><td>–</td><td>[248]</td></tr><tr><td>A5</td><td>PCM Products Limited</td><td>Organic</td><td>5</td><td>170</td><td>0.22</td><td>–</td><td>[59]</td></tr><tr><td>PCM-OM05P</td><td>saveENRG PCM</td><td>Paraffin</td><td>5</td><td>213/217</td><td>0.12/0.13</td><td>–</td><td>[247]</td></tr><tr><td>FS05-P</td><td>saveE-Pluss</td><td>Paraffin</td><td>5/4</td><td>217/213</td><td>0.123/0.136</td><td>–</td><td>[51]</td></tr><tr><td>OM05-P</td><td>saveE-Pluss</td><td>Paraffin</td><td>6/5</td><td>213/271</td><td>0.12/0.13</td><td>8.5</td><td>[51]</td></tr><tr><td>Tetradecane-C14</td><td>RU Entropy</td><td>Paraffin</td><td>5.8</td><td>220</td><td>0.24</td><td>1.5–5</td><td>[139]</td></tr><tr><td>ATP 6</td><td>Axiotherm GmbH</td><td>Organic</td><td>6</td><td>275</td><td>0.2</td><td>–</td><td>[60]</td></tr><tr><td>PCM6</td><td>Microteklabs</td><td>Paraffin</td><td>6</td><td>185</td><td>0.140</td><td>120.4</td><td>[132]</td></tr><tr><td>A6</td><td>PCM Products Limited</td><td>Organic</td><td>6</td><td>185</td><td>0.21</td><td>–</td><td>[59]</td></tr><tr><td>BioPCM 6</td><td>Phase Change Solutions</td><td>Bio-based</td><td>6</td><td>210</td><td>–</td><td>–</td><td>[135]</td></tr><tr><td>ClimSel C7</td><td>Climator</td><td>Hydrated salts</td><td>7</td><td>135</td><td>0.69/0.81</td><td>–</td><td>[130]</td></tr><tr><td>A7</td><td>PCM Products Limited</td><td>Organic</td><td>7</td><td>190</td><td>0.22</td><td>–</td><td>[59]</td></tr><tr><td>PCM-(7)</td><td>TEAP PCM</td><td>Hydrated salts</td><td>7</td><td>300</td><td>–</td><td>–</td><td>[133]</td></tr><tr><td>A8</td><td>PCM Products Limited</td><td>Organic</td><td>8</td><td>180</td><td>0.21</td><td>–</td><td>[59]</td></tr><tr><td>OM08</td><td>saveE-Pluss</td><td>Bio-based</td><td>7/8</td><td>154/150</td><td>0.118/0.235</td><td>9.7</td><td>[51]</td></tr><tr><td>PureTemp 8</td><td>PureTemp LLC</td><td>Bio-based</td><td>8</td><td>178</td><td>0.14/0.22</td><td>6–10</td><td>[61]</td></tr></tbody></table>

## Appendix C

<caption>**Table 3**</caption>

Summary of several studies investigating the integration of PCM in different refrigeration systems.

<table><thead><tr><th>Refrigeration system</th><th>PCM emplacement</th><th>PCM melting point (°C); type</th><th>Approach</th><th>Results</th><th>Reference</th><th>Year</th></tr></thead><tbody><tr><td rowspan="10">Cold room</td><td>Ext. walls</td><td>35; paraffin</td><td>Experimental</td><td>- The results showed that the peak heat transfer rate was reduced by 5.55–8.57 % and shifted by 3.5–4.5 h.</td><td>[146]</td><td>2016</td></tr><tr><td rowspan="2">Ceiling</td><td>-20; salt hydrate</td><td>Experimental</td><td>- The PCM is used to shift consumption during peak hours.<br/>- The first cold room achieved a total annual reduction in consumption of 8.2 MWh, or 30 %.<br/>- The second cold room achieved 50.8 MWh or 39 %.</td><td>[149]</td><td>2016</td></tr><tr><td>Salt hydrate</td><td>Experimental</td><td>- During the 10-day study period, energy consumption was reduced by 18 % compared to the baseline.<br/>- The peak period consumption dropped from 6 kW to &lt;1 kW an 85 % reduction,<br/>- The peak period run-time was reduced by 60 %.</td><td>[152]</td><td>–</td></tr><tr><td rowspan="4">Next to the evaporator's fan</td><td>–</td><td>Experimental</td><td>- The peak period consumption was reduced by 43 %/day.<br/>- Refrigeration energy consumption reduced by 35 %.</td><td>[153]</td><td>–</td></tr><tr><td>5; paraffin</td><td>Experimental</td><td>- The on-off cycles of the compressor and the energy consumption were reduced by ~50 % and 16 %, respectively.</td><td>[163]</td><td>2017</td></tr><tr><td>-30; salt hydrate</td><td>Numerical</td><td>- The inorganic PCM prolongs the compressor off time from 4 min to 24 min.<br/>- Reduces the number of On-off cycles was reduced by 82 %.<br/>- The total daily energy usage was reduced by 6.55 %/day.</td><td>[165]</td><td>2022</td></tr><tr><td>7; paraffin</td><td>Experimental</td><td>- The peak heat flux was reduced by an average of 29.1 % compared to the reference case.<br/>- The total heat flow across the refrigerated trailer was reduced by an average of 16.3 %.</td><td>[25]</td><td>2010</td></tr><tr><td rowspan="2">Refrigerated trucks</td><td>20; paraffin</td><td>Experimental</td><td>- The integration of PCM as an insulating panel reduces the heat transfer through the walls.<br/>- A 25 % reduction in energy consumption of the passive prototype.</td><td>[27]</td><td>2014</td></tr><tr><td>Next to the evaporator's fan</td><td>-30; eutectic (sodium chloride, glycerol, water)</td><td>Experimental</td><td>- The results showed that the internal temperature can be maintained at -12.3 °C, -14.5 °C, and -16.5 °C for 16.6 h, 14.7 h, and 9.4 h when using PCM.</td><td>[28]</td><td>2022</td></tr><tr><td rowspan="2">Domestic refrigerator</td><td>Int. walls</td><td>-15.4; salt hydrate (ammonium chloride)</td><td>Experimental/ numerical</td><td>- The results show that the PCMs prevent the rapid increase of the internal temperature during compressor off time, and reduce the on-off cycle.<br/>- The PCM-based freezer had lower temperature fluctuations than the no-PCM freezer, which led to better food quality.<br/>- The energy consumption of the PCM-based system was decreased by 8 % and 7 % during the defrost cycle and door opening, respectively.</td><td>[20] [157] [158]</td><td>2010</td></tr><tr><td>Racks</td><td>5; polyethylene glycol</td><td>Experimental</td><td>- The temperature inside the refrigerator was 3 °C lower when using PCM during door opening and power loss tests.<br/>- The PCM can maintain the product temperature almost constant, thus, guaranteeing a better quality.</td><td>[161]</td><td>2017</td></tr></tbody></table>

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<table><caption>Table 3 (continued)</caption><thead><tr><th>Refrigeration system</th><th>PCM emplacement</th><th>PCM melting point (°C); type</th><th>Approach</th><th>Results</th><th>Reference</th><th>Year</th></tr></thead><tbody><tr><td rowspan="10"></td><td rowspan="4">Condenser</td><td>-20; -15; -10; polyethylene glycol</td><td>Experimental</td><td>- The PCM reduces internal temperature fluctuations.<br/>- The PCM extends the compressor off time and decreases the run time, resulting in an 8.37 % reduction in daily energy consumption.</td><td>[250]</td><td>2020</td></tr><tr><td>0; water<br/>34; paraffin</td><td>Experimental</td><td>- PCMs decrease the condenser temperature by 3-10 °C depending on the PCM type.<br/>- Shorten the compressor running time leading to a 3-10 % reduction in consumption of energy.</td><td>[122]</td><td>2015</td></tr><tr><td>30; paraffin</td><td>Experimental</td><td>- The energy consumption of the refrigerator has been reduced by 12 %.<br/>- Reduces internal temperature fluctuations, thus preserving the goods in good condition.</td><td>[19]<br/>[167]</td><td>2013<br/>2011</td></tr><tr><td>-</td><td>Experimental</td><td>- The power consumption of the refrigerator was 21 % lower when using PCM<br/>- COP was increased by 17.6 % when compared with a normal refrigerator.</td><td>[168]</td><td>2017</td></tr><tr><td rowspan="4">Evaporator</td><td>37; polyethylene glycol<br/>20; polyethylene glycol</td><td>Experimental</td><td>- The refrigerators equipped with PCM show a lower internal temperature fluctuation.<br/>- The daily energy consumption of refrigerators was reduced by 8.7-13.4 %, dropping from 0.76 kWh to 0.66-0.69 kWh.</td><td>[154]</td><td>2013</td></tr><tr><td>Ethylene glycol</td><td>Experimental/numerical</td><td>- Reduced the compressor running time by 17 % to 30 %.<br/>- Using PCM enhanced the refrigerator COP by 20 %.<br/>- Maintain the temperature at -10 °C for 6 to 8 h without a power supply, compared to 1 h without PCM.</td><td>[22]</td><td>2018</td></tr><tr><td>-</td><td>Experimental/numerical</td><td>- The PCM increases the COP of the refrigerator by 55-60 % depending on the thermal load.<br/>- Reduced internal temperature fluctuations.</td><td>[23]</td><td>2013</td></tr><tr><td>-4; paraffin<br/>35; paraffin</td><td>Experimental</td><td>- Increased the evaporator temperature by 6-8 °C<br/>- Decreased the condenser temperature by 6 °C<br/>- 12 % to 17 % of the power consumption reduction was achieved.</td><td>[155]</td><td>2015</td></tr><tr><td rowspan="10">Commercial refrigerator</td><td>0; water<br/>-3; eutectic aqueous solution</td><td>Experimental</td><td>- The PCMs continue to cool the refrigerator for 5 to 9 h without a power supply.<br/>- Increased evaporating pressure by 0.11 bar and 0.14 bar using eutectic PCM and water, respectively.<br/>- Enhanced the COP by 10-31 %.</td><td>[119]</td><td>2009</td></tr><tr><td>4; paraffin</td><td>Experimental/numerical</td><td>- The COP of the refrigerator was improved by 8 % when using the PCM.</td><td>[156]</td><td>2017</td></tr><tr><td>-9; eutectic</td><td>Experimental/numerical</td><td>- The integration of PCM increases the refrigerator COP by 5 % to 15 %.</td><td>[151]<br/>[162]</td><td>2005<br/>2008</td></tr><tr><td>0; water<br/>-5; salt hydrate<br/>-10; salt hydrate</td><td>Experimental</td><td>- PCM stabilizes the evaporation and the internal temperatures.<br/>- The compressor run time was reduced by about 5-36 % compared to the base case.<br/>- The COP of the refrigerator was enhanced by 20-27 % depending on thermal loads.</td><td>[121]<br/>[166]</td><td>2013<br/>2015</td></tr><tr><td>0; water</td><td>Experimental/numerical</td><td>- Using PCM 17.4 % reduction in energy consumption.</td><td>[124]</td><td>2018</td></tr><tr><td>0; water</td><td>Experimental/numerical</td><td>- PCM continues to cool the compartment for 2.9-4.8 h.</td><td>[21]<br/>[125]</td><td>2014<br/>2013</td></tr><tr><td>-18; salt hydrate (sodium nitrate)</td><td>Experimental</td><td>- During door opening, the internal temperature was lower when using PCM by an average of 3 °C.</td><td>[160]</td><td>2012</td></tr><tr><td>-6; eutectic</td><td>Experimental</td><td>- PCM on the racks: the compressor operates less than without PCM, resulting in a 4.4 % reduction in energy consumption.<br/>- PCM on the back: the compressor energy consumption was 8 % higher<br/>- During power loss, the internal temperature reaches 16 °C in 6 h, 17 h, and 20 h for no-PCM, PCM on the racks, and on the back, respectively.</td><td>[150]</td><td>2020</td></tr><tr><td>Racks</td><td>-2; ice gel</td><td>Experimental</td><td>- PCM-based configuration has a lower and more stable temperature (1.5 °C) than the no-PCM configuration (8.5 °C).<br/>- The product temperature of the PCM-based configuration was 1 °C less than that of the no-PCM configuration.</td><td>[126]</td><td>2019</td></tr><tr><td>Racks &amp; rear duct</td><td>-18; salt hydrate<br/>-21.3; salt hydrate</td><td>Experimental</td><td>- Two PCMs were used: C-18 and E-21 with a melting temperature of -18 °C and 21.3 °C, respectively.<br/>- The authors reported that for the empty cabinet, the air temperature rose to reach 0 °C within 6.5 h and 8 h when C-18 and E-21 were used, compared to 1.5 h for the reference case.<br/>- In 24 h the product temperature went from -20 °C to 12 °C, 7 °C and 4 °C for no PCM, C-18, and E-21 cases, respectively.</td><td>[120]</td><td>2015</td></tr><tr><td>Rear duct</td><td>0; water</td><td>Numerical</td><td>- The model predicted that 6 mm is the optimal thickness for a PCM, reducing the compressor run-time ratio by 26 %.</td><td>[123]</td><td>2017</td></tr><tr><td>Rear duct</td><td>4; paraffin<br/>0; water</td><td>Experimental/numerical</td><td>- The results showed that the integration of PCM acts as an additional evaporator.</td><td>[118]</td><td>2014</td></tr></tbody></table>

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<table><caption>**Table 3 (continued)**</caption><thead><tr><th>Refrigeration system</th><th>PCM emplacement</th><th>PCM melting point (°C); type</th><th>Approach</th><th>Results</th><th>Reference</th><th>Year</th></tr></thead><tbody><tr><td rowspan="3">Refrigerated container</td><td rowspan="2">Ceiling</td><td>-26; salt hydrate (sodium nitrate)</td><td>Experimental</td><td>- Reduce the compressor on-off cycle, and the total energy consumption by 77.5 %.</td><td rowspan="2">[8]</td><td rowspan="2">2015</td></tr><tr><td>5; paraffin</td><td>Experimental</td><td>- The results showed that without a refrigeration system, the PCM maintains the internal temperature around -22 °C for up to seven days.</td></tr><tr><td>Walls</td><td>35; paraffin</td><td>Experimental/numerical</td><td>- The authors reported that only charging the PCMs one single time, could maintain the internal temperature around 12 °C for 94.6 h.<br/>- The peak heat transfer rate was reduced by 20-25 % and delayed by 2-3 h.<br/>- The daily energy consumption reduced by 4.55-4.74 % compared to a standard container.</td><td>[30]</td><td>2021</td></tr><tr><td rowspan="2">Refrigeration plant</td><td rowspan="2">Between:<br/>- Compressor &amp; Condenser.<br/>- Condenser &amp; TEV<br/>- Evaporator &amp; Compressor.</td><td>21; eutectic</td><td>Experimental/numerical</td><td>- The results showed that PCMA and PCMB are the best configurations, while PCMC is the worst one.</td><td>[31]</td><td rowspan="2">2007</td></tr><tr><td>8; eutectic<br/>21; eutectic</td><td></td><td>- PCMA and PCMB enhanced the COP by 6 and 8 %, respectively, while no improvement was observed for configuration PCMC.</td><td>[32]<br/>[33]</td></tr></tbody></table>

## Appendix D

<table><caption>**Table 4**

Overview of thermal properties of bio-based materials.</caption><thead><tr><th rowspan="2">Material</th><th rowspan="2"></th><th>Melting/freezing point</th><th>Latent heat</th><th rowspan="2">Reference</th><th rowspan="2">Year</th></tr><tr><th>°C</th><th>J·g<sup>-1</sup></th></tr></thead><tbody><tr><td rowspan="2">Fatty acids and esters</td><td>Carbon no.</td><td></td><td></td><td></td><td></td></tr><tr><td>Methyl decanoate</td><td>11</td><td>-13</td><td>-</td><td>[181]</td><td>2009</td></tr><tr><td>Linolenic (D9c, D12c, D15c)</td><td>18</td><td>-11</td><td>115.71</td><td>[181]</td><td>2009</td></tr><tr><td>Linoleic (D9c, D12c)</td><td>18</td><td>-10.3</td><td>85.5</td><td>[191]</td><td>2021</td></tr><tr><td>Caproic acid</td><td>6</td><td>-7.8</td><td>117.8</td><td>[190]</td><td>2002</td></tr><tr><td>Oleic:capric acids</td><td>-</td><td>-6.81</td><td>77.92</td><td>[251]</td><td>2024</td></tr><tr><td>Oleic acid (D9c)</td><td>18</td><td>-4.5</td><td>45.3</td><td>[190]</td><td>2002</td></tr><tr><td>Myristoleic (D9c)</td><td>14</td><td>-4</td><td>-</td><td>[181]</td><td>2009</td></tr><tr><td rowspan="2">Ester</td><td>Carbon no.</td><td></td><td></td><td></td><td></td></tr><tr><td>γ-Valerolactone</td><td>5</td><td>-31.1</td><td>109.8</td><td>[183]</td><td>2019</td></tr><tr><td>ε-Caprolactone</td><td>6</td><td>-1.5</td><td>121.7</td><td></td><td></td></tr><tr><td>Erythritol tetra laureate</td><td></td><td>-9.03/-12.86</td><td>161.39/150.52</td><td>[182]</td><td>2013</td></tr><tr><td rowspan="2">Methyl ester</td><td></td><td>-37.43</td><td>-</td><td rowspan="2">[181]</td><td rowspan="2">2009</td></tr><tr><td>8</td><td>-12.17</td><td>-</td></tr><tr><td rowspan="2">Ethyl ester</td><td></td><td>-44.74</td><td>-</td><td></td><td></td></tr><tr><td>8</td><td>-19.43</td><td>-</td><td></td><td></td></tr><tr><td rowspan="2">Propyl ester</td><td></td><td>-45.68</td><td>-</td><td></td><td></td></tr><tr><td>8</td><td>-4.35</td><td>-</td><td></td><td></td></tr><tr><td rowspan="2">Butyl ester</td><td></td><td>-43.33</td><td>-</td><td></td><td></td></tr><tr><td>8</td><td>-8.48</td><td>-</td><td></td><td></td></tr><tr><td rowspan="3">Triglycerides</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>α-Tricaprylin</td><td></td><td>-51/-54</td><td>36.4</td><td>[184]</td><td>2020</td></tr><tr><td>α-Tripelargonin</td><td></td><td>-26/-30</td><td>69.4</td><td></td><td></td></tr><tr><td>α-Tricaprin</td><td></td><td>-11.5/-9</td><td>103.3</td><td></td><td></td></tr><tr><td rowspan="2">Edible oil</td><td>wt%</td><td></td><td></td><td></td><td></td></tr><tr><td>Corn oil</td><td>-</td><td>-24.6/-22</td><td>52</td><td>[199,252]</td><td>2020; 2022</td></tr><tr><td>Canola oil</td><td>-</td><td>-20</td><td>57.5</td><td>[198]<br/>[200]</td><td>2016<br/>2004</td></tr><tr><td>Canola oil-bee wax</td><td>90:10</td><td>-16.7</td><td>367.6</td><td>[188]</td><td>2023</td></tr><tr><td>Soya oil:bee wax</td><td>90:10</td><td>-13.6</td><td>22.9</td><td>[188]</td><td>2023</td></tr><tr><td>Sunflower oil</td><td>-</td><td>-9.8/-44.8</td><td>61/57.5</td><td>[252]</td><td>2022</td></tr><tr><td>Soya oil:water</td><td>12.5:87.5</td><td>-8</td><td>-</td><td>[186]</td><td>2016</td></tr><tr><td rowspan="3">Corn oil:water</td><td>10:90</td><td>-7.5</td><td>171.72</td><td>[185]</td><td>2018</td></tr><tr><td>7.5:92.5</td><td>-6</td><td>230.7</td><td>[187]</td><td>2019</td></tr><tr><td>5:95</td><td>-4.5</td><td>227.8</td><td></td><td></td></tr><tr><td rowspan="3">Soya oil:water</td><td>10:90</td><td>-8</td><td>185.94</td><td>[185]</td><td>2018</td></tr><tr><td>7.5:92.5</td><td>-5.5</td><td>224.6</td><td></td><td></td></tr><tr><td>5:95</td><td>-4</td><td>230.7</td><td></td><td></td></tr><tr><td>Soya oil</td><td>-</td><td>-3.53</td><td>47.4</td><td>[197]</td><td>2023</td></tr><tr><td>Non-edible oil</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Olive mill waste</td><td></td><td>-4.5/-11</td><td>105/97</td><td>[207]</td><td>2017</td></tr></tbody></table>

(continued on next page)
<table><caption>**Table 4 (continued)**</caption><thead><tr><th rowspan="2">Material</th><th>Melting/freezing point</th><th>Latent heat</th><th rowspan="2">Reference</th><th rowspan="2">Year</th></tr><tr><th>°C</th><th>J·g<sup>-1</sup></th></tr></thead><tbody><tr><td>Avocado seed oil</td><td>-4.33</td><td>86.84</td><td>[238]</td><td>2024</td></tr><tr><td>Coffee oil</td><td>3.78/-1.51</td><td>50.20/50.31</td><td>[189]</td><td>2023</td></tr><tr><td>Date seeds oil</td><td>-3/3</td><td>60/70</td><td>[213]</td><td>2021</td></tr><tr><td></td><td></td><td></td><td>[215]</td><td>2013</td></tr><tr><td></td><td></td><td></td><td>[216]</td><td>2016</td></tr><tr><td>Animal fat wastes</td><td></td><td></td><td></td><td></td></tr><tr><td>Salmon</td><td>-70 to 13.5</td><td>40</td><td>[218]</td><td>2005</td></tr><tr><td>Red salmon</td><td>-69.6 to -0.36</td><td>40</td><td>[219]</td><td>2005</td></tr><tr><td>Pink salmon</td><td>-64.7 to 20.8</td><td>39</td><td></td><td></td></tr><tr><td>Catfish</td><td>-44.3 to 11.4</td><td>75.1</td><td>[217]</td><td>2008</td></tr><tr><td>Pollock</td><td>-35 to 15</td><td>35</td><td></td><td></td></tr><tr><td>Sugar alcohols/polyols solutions</td><td>wt%</td><td></td><td></td><td></td></tr><tr><td>Corn syrup</td><td>30:70</td><td>-5</td><td>-</td><td>[234]</td><td>1996</td></tr><tr><td></td><td>60:40</td><td>-23</td><td></td><td></td><td></td></tr><tr><td>Glycerol</td><td>12:88</td><td>-7</td><td>170</td><td>[239]</td><td>2023</td></tr><tr><td></td><td>40:60</td><td>-18</td><td>86.2</td><td>[253]</td><td>2008</td></tr><tr><td>Glycerol:Ni(NO<sub>3</sub>)<sub>2</sub>6H<sub>2</sub>O</td><td>97:3</td><td>-9.7/-9.8</td><td>163</td><td>[254]</td><td>2019</td></tr><tr><td>Glucose</td><td>30:70</td><td>-5</td><td>-</td><td>[234]</td><td>1996</td></tr><tr><td></td><td>60:40</td><td>-20</td><td></td><td></td><td></td></tr><tr><td>Lactitol</td><td>30:70</td><td>-60</td><td>-</td><td></td><td></td></tr><tr><td></td><td>60:40</td><td>-24</td><td></td><td></td><td></td></tr><tr><td>Sucrose</td><td>30:70</td><td>-2</td><td>-</td><td></td><td></td></tr><tr><td></td><td>60:40</td><td>-13</td><td></td><td></td><td></td></tr><tr><td>Sorbitol</td><td>30:70</td><td>-5</td><td>-</td><td></td><td></td></tr><tr><td></td><td>60:40</td><td>-20</td><td></td><td></td><td></td></tr><tr><td>Sorbitol</td><td>-</td><td>-15.6</td><td>269</td><td>[237]</td><td>2019</td></tr><tr><td></td><td></td><td>-18.1</td><td>236.2</td><td></td><td></td></tr><tr><td>Xylitol</td><td>30:70</td><td>-4</td><td>-</td><td>[234]</td><td>1996</td></tr><tr><td></td><td>60:40</td><td>-17</td><td></td><td></td><td></td></tr><tr><td>Xylose</td><td>30:70</td><td>-4</td><td>-</td><td></td><td></td></tr><tr><td></td><td>60:40</td><td>-14</td><td></td><td></td><td></td></tr></tbody></table>

## Data availability

No data was used for the research described in the article.

## References

[1] UN, World Population Prospects 2024, United Nations, Department of Economic and Social Affairs, Population Division, 2024. http://population.un.org/wpp/. accessed November 14, 2024.

[2] United Nations Environment Programme, Food Waste Index Report 2024. Think Eat Save: Tracking Progress to Halve Global Food Waste, United Nations, 2024. https://wedocs.unep.org/20.500.11822/45230.

[3] FAO, Tracking Progress on Food and Agriculture-related SDG Indicators 2023, Food and Agriculture Organization, Rome, Italy, 2023, https://doi.org/10.4060/cc7088en.

[4] G.O. Adegoke, A.A. Olapade, Preservation of plant and animal foods: an overview, in: R. Bhat, A. Karim Alias, G. Paliyath (Eds.), Prog. Food Preserv, 1st ed., Wiley, 2012, pp. 603–611, https://doi.org/10.1002/9781119962045.ch28.

[5] M.S. Rahman, Handbook of Food Preservation, Second edition, CRC Press, Boca Raton (Fla.), 2007, https://doi.org/10.1201/9781420017373.

[6] J.L. Dupont, P. Domanski, P. Lebrun, F. Ziegler, The Role of Refrigeration in the Global Economy 38th Informatory Note on Refrigeration Technologies, International Institute of Refrigeration (IIR), 2019, https://doi.org/10.18462/iif.NItec38.06.2019.

[7] M. Liu, W. Saman, F. Bruno, Development of a novel refrigeration system for refrigerated trucks incorporating phase change material, Appl. Energy 92 (2012) 336–342, https://doi.org/10.1016/j.apenergy.2011.10.015.

[8] R. Sepe, E. Armentani, A. Pozzi, Development and stress behaviour of an innovative refrigerated container with PCM for fresh and frozen goods, Multidiscip. Model. Mater. Struct. 11 (2015) 202–215, https://doi.org/10.1108/MMMS-05-2014-0030.

[9] G. Sonnenrein, E. Baumhögger, A. Elsner, A. Morbach, M. Neukötter, A. Paul, J. Vrabeč, Improving the performance of household refrigerating appliances through the integration of phase change materials in the context of the new global refrigerator standard IEC 62552:2015, Int. J. Refrig. 119 (2020) 448–456, https://doi.org/10.1016/j.ijrefrig.2020.07.025.

[10] E. Oró Prim, Thermal Energy Storage (TES) Using Phase Change Materials (PCM) for Cold Applications, Universitat de Lleida, 2013.

[11] A.A.M. Omara, A.A.M. Mohammedali, Thermal management and performance enhancement of domestic refrigerators and freezers via phase change materials: a review, Innov. Food Sci. Emerg. Technol. 66 (2020) 102522, https://doi.org/10.1016/j.ifset.2020.102522.

[12] H. Ritchie, P. Rosado, M. Roser, Electricity Mix, Our World Data, 2023.

[13] Global CO₂ Emissions by Sector, 2019–2022, IEA, Paris, 2021.

[14] J. Sarr, J.L. Dupont, J. Guilpart, The carbon footprint of the cold chain, in: 7th Informatory Note on Refrigeration and Food, 2021, https://doi.org/10.18462/iir. Infood07.04.2021.

[15] Y. Pahamli, M.S. Valipour, Application of phase change materials in refrigerator and freezer appliances: a comprehensive review, J. Heat Mass Transf. Res. 8 (2021) 87–104, https://doi.org/10.22075/JHMTR.2021.21860.1316.

[16] S. Sarkar, S. Mstry, S.T. Mhaske, Developments in phase change material (PCM) doped energy efficient polyurethane (PU) foam for perishable food cold-storage applications: a review, J. Energy Storage 50 (2022) 104620, https://doi.org/10.1016/j.est.2022.104620.

[17] B. Nie, A. Palacios, B. Zou, J. Liu, T. Zhang, Y. Li, Review on phase change materials for cold thermal energy storage applications, Renew. Sust. Energ. Rev. 134 (2020) 110340, https://doi.org/10.1016/j.rser.2020.110340.

[18] P. Schalbart, D. Leducq, G. Alvarez, Frozen products stabilisation by phase change material, in: 2nd IIR Int. Conf. Sustain. Cold Chain, The International Institute of Refrigeration (IIR), 2013, pp. 2–4. https://iifir.org/en/fridoc/froze%0An-products-stabilisation-by-phase-change-material-29311.

[19] W.L. Cheng, X.D. Yuan, Numerical analysis of a novel household refrigerator with shape-stabilized PCM (phase change material) heat storage condensers, Energy 59 (2013) 265–276, https://doi.org/10.1016/j.energy.2013.06.045.

[20] B. Gin, M.M. Farid, P. Bansal, Modeling of phase change material implemented into cold storage application, HVAC&R Res. 17 (2011) 257–267, https://doi.org/10.1080/10789669.2011.572222.

[21] A.C. Marques, G.F. Davies, G.G. Maidment, J.A. Evans, I.D. Wood, Novel design and performance enhancement of domestic refrigerators with thermal storage, Appl. Therm. Eng. 63 (2014) 511–519, https://doi.org/10.1016/j.apithermaleng.2013.11.043.

[22] P. Geete, H.P. Singh, S.K. Somani, Performance analysis by implementation of micro-encapsulated PCM in domestic refrigerator: a novel approach, Int. J. Appl. Eng. Res. 13 (2018) 14365–14371.

[23] R. Rahman, Performance improvement of a domestic refrigerator using phase change material (PCM), IOSR J. Mech. Civ. Eng. 10 (2013) 08–16, https://doi.org/10.9790/1684-1040816.

[24] M. Liu, W. Saman, F. Bruno, Computer simulation with TRNSYS for a mobile refrigeration system incorporating a phase change thermal storage unit, Appl. Energy 132 (2014) 226–235, https://doi.org/10.1016/j.apenergy.2014.06.066.

[25] M. Ahmed, O. Meade, M.A. Medina, Reducing heat transfer across the insulated walls of refrigerated truck trailers by the application of phase change materials, https://doi.org/10.1016/j.apenergy.2014.06.066.
Energy Convers. Manag. 51 (2010) 383–392, https://doi.org/10.1016/j. enconman.2009.09.003.

[26] T. Leungtongkum, D. Flick, H.M. Hoang, D. Steven, A. Delahaye, O. Laguerre, Insulated box and refrigerated equipment with PCM for food preservation: state of the art, J. Food Eng. 317 (2022) 110874, https://doi.org/10.1016/j. jfoodeng.2021.110874.

[27] P. Glouannec, B. Michel, G. Delamarre, Y. Grohens, Experimental and numerical study of heat transfer across insulation wall of a refrigerated integral panel van, Appl. Therm. Eng. 73 (2014) 196–204, https://doi.org/10.1016/j. applthermal暖.2014.07.044.

[28] G. Liu, Q. Li, J. Wu, R. Xie, Y. Zou, A. Marson, A. Scipioni, A. Manzardo, Improving system performance of the refrigeration unit using phase change material (PCM) for transport refrigerated vehicles: an experimental investigation in South China, J. Energy Storage 51 (2022) 104435, https://doi.org/10.1016/j. est.2022.104435.

[29] A. Mousazade, R. Rafee, M.S. Valipour, Thermal performance of cold panels with phase change materials in a refrigerated truck, Int. J. Refrig. 120 (2020) 119–126, https://doi.org/10.1016/j.jrefrig.2020.09.003.

[30] S. Tong, B. Nie, Z. Li, C. Li, B. Zou, L. Jiang, Y. Jin, Y. Ding, A phase change material (PCM) based passively cooled container for integrated road-rail cold chain transportation — an experimental study, Appl. Therm. Eng. 195 (2021) 117204, https://doi.org/10.1016/j.applthermal暖.2021.117204.

[31] F. Wang, G. Maidment, J. Missenden, R. Tozer, The novel use of phase change materials in refrigeration plant. Part 1: experimental investigation, Appl. Therm. Eng. 27 (2007) 2893–2901, https://doi.org/10.1016/j. applthermal暖.2005.06.011.

[32] F. Wang, G. Maidment, J. Missenden, R. Tozer, The novel use of phase change materials in refrigeration plant. Part 2: dynamic simulation model for the combined system, Appl. Therm. Eng. 27 (2007) 2902–2910, https://doi.org/10.1016/j.applthermal暖.2005.06.009.

[33] F. Wang, G. Maidment, J. Missenden, R. Tozer, The novel use of phase change materials in refrigeration plant. Part 3: PCM for control and energy savings, Appl. Therm. Eng. 27 (2007) 2911–2918, https://doi.org/10.1016/j. applthermal暖.2005.06.010.

[34] E. Oró, L. Miró, M.M. Farid, V. Martin, L.F. Cabeza, Energy management and CO₂ mitigation using phase change materials (PCM) for thermal energy storage (TES) in cold storage and transport, Int. J. Refrig. 42 (2014) 26–35, https://doi.org/10.1016/j.jrefrig.2014.03.002.

[35] K. Du, J. Calautit, Z. Wang, Y. Wu, H. Liu, A review of the applications of phase change materials in cooling, heating and power generation in different temperature ranges, Appl. Energy 220 (2018) 242–273, https://doi.org/10.1016/j.apenergy.2018.03.005.

[36] Z. Liu, D. Zhao, Q. Wang, Y. Chi, L. Zhang, Performance study on air-cooled household refrigerator with cold storage phase change materials, Int. J. Refrig. 79 (2017) 130–142, https://doi.org/10.1016/j.jrefrig.2017.04.009.

[37] L. Yang, U. Villalobos, B. Akhmetov, A. Gil, J.O. Khor, A. Palacios, Y. Li, Y. Ding, L.F. Cabeza, W.L. Tan, A. Romagnoli, A comprehensive review on sub-zero temperature cold thermal energy storage materials, and applications: state of the art and recent developments, Appl. Energy 288 (2021) 116555, https://doi.org/10.1016/j.apenergy.2021.116555.

[38] S.Z.D. Cheng, Thermodynamics and kinetics of phase transitions, in: Phase Transit. Polym. Role Metastable States, 1st ed., Elsevier, 2008, pp. 17–59, https://doi.org/10.1007/978-3-7091-2660-8_1.

[39] E. Oró, A. de Gracia, A. Castell, M.M. Farid, L.F. Cabeza, Review on phase change materials (PCMs) for cold thermal energy storage applications, Appl. Energy 99 (2012) 513–533, https://doi.org/10.1016/j.apenergy.2012.03.058.

[40] P.K.S. Rathore, S.K. Shukla, Potential of macroencapsulated pcm for thermal energy storage in buildings: a comprehensive review, Constr. Build. Mater. 225 (2019) 723–744, https://doi.org/10.1016/j.conbuildmat.2019.07.221.

[41] B. Cárdenas, N. León, High temperature latent heat thermal energy storage: phase change materials, design considerations and performance enhancement techniques, Renew. Sust. Energ. Rev. 27 (2013) 724–737, https://doi.org/10.1016/j.rser.2013.07.028.

[42] G. Hameed, M.A. Ghafoor, M. Yousaf, M. Imran, M. Zaman, A. Elkamel, A. Haq, M. Rizwan, T. Wilberforce, M.A. Abdelkareem, A.G. Olabi, Low temperature phase change materials for thermal energy storage: current status and computational perspectives, Sustain Energy Technol Assess 50 (2022) 101808, https://doi.org/10.1016/j.seta.2021.101808.

[43] O. Okogeri, V.N. Stathopoulos, What about greener phase change materials? A review on biobased phase change materials for thermal energy storage applications, Int. J. Thermofluids 10 (2021) 100081, https://doi.org/10.1016/j. ijft.2021.100081.

[44] V.V. Tyagi, K. Chopra, R.K. Sharma, A.K. Pandey, S.K. Tyagi, M.S. Ahmad, A. Sari, R. Kothari, A comprehensive review on phase change materials for heat storage applications: development, characterization, thermal and chemical stability, Sol. Energy Mater. Sol. Cells 234 (2022) 111392, https://doi.org/10.1016/j. solmat.2021.111392.

[45] K.Y. Leong, S. Hasbi, B.A. Gurunathan, State of art review on the solidification and melting characteristics of phase change material in triplex-tube thermal energy storage, J. Energy Storage 41 (2021) 102932, https://doi.org/10.1016/j. est.2021.102932.

[46] P.K.S. Rathore, S.K. Shukla, Enhanced thermophysical properties of organic PCM through shape stabilization for thermal energy storage in buildings: a state of the art review, Energy Build. 236 (2021) 110799, https://doi.org/10.1016/j. enbuild.2021.110799.

[47] B.M. Tripathi, S.K. Shukla, P.K.S. Rathore, A comprehensive review on solar to thermal energy conversion and storage using phase change materials, J. Energy Storage 72 (2023) 108280, https://doi.org/10.1016/j.est.2023.108280.

[48] Y. Sheikh, M.O. Hamdan, S. Sakhi, A review on micro-encapsulated phase change materials (EPCM) used for thermal management and energy storage systems: fundamentals, materials, synthesis and applications, J. Energy Storage 72 (2023) 108472, https://doi.org/10.1016/j.est.2023.108472.

[49] Z. Ouaujia, A. Ousegui, Energy efficiency in buildings: numerical study of the impact of integrating phase change materials into the walls, J. At. Mol. Condens. Matter Nanol. Phys. 7 (2020) 14, https://doi.org/10.26713/jamcnp.v7i3.1548.

[50] R. Chandran, M. Hasanuzzaman, M. Arici, L. Kumar, Energy, economic and environmental impact analysis of phase change materials for cold chain transportation in Malaysia, J. Energy Storage 55 (2022) 105481, https://doi.org/10.1016/j.EST.2022.105481.

[51] Plusz, PLUSZ® (n.d.). https://plusz.co.in/ (accessed July 16, 2024).

[52] T. Hásl, J. Irířcek, M. Jeremiás, J. Farták, M. Pohorelý, Cost/performance analysis of commercial-grade organic phase-change materials for low-temperature heat storage, Energies 13 (2019) 5, https://doi.org/10.3390/en13010005.

[53] J.R. Hirshey, N. Kumar, T. Turnaoglu, K.R. Gluesenkamp, S. Graham, Review of low-cost organic and inorganic phase change materials with phase change temperature between 0 °C and 65 °C, in: Int. High Perform. Build. Conf., 2021. https://docs.lib.purdue.edu/ihpbc/389/.

[54] Y. Sheikh, M.O. Hamdan, S. Sakhi, A review on micro-encapsulated phase change materials (EPCM) used for thermal management and energy storage systems: fundamentals, materials, synthesis and applications, J. Energy Storage 72 (2023) 108472, https://doi.org/10.1016/j.est.2023.108472.

[55] J. Kosny, N. Shukla, A. Fallahi, Cost Analysis of Simple Phase Change Material- enhanced Building Envelopes in Southern U.S. Climates, U.S. Department of Energy, United States, 2013, https://doi.org/10.2172/1067934.

[56] M. Kenisarin, K. Mahkamov, Salt hydrates as latent heat storage materials: thermophysical properties and costs, Sol. Energy Mater. Sol. Cells 145 (2016) 255–286, https://doi.org/10.1016/j.solmat.2015.01029.

[57] M.M. Ghafurian, B. Elmegaard, P. Weinberger, A. Arabkoohsar, Salt hydrates in renewable energy systems: a thorough review, Energy (2024) 133808, https://doi.org/10.1016/j.energy.2024.133808.

[58] Rubitherm GmbH, (n.d.). https://www.rubitherm.eu/en/ (accessed August 18, 2024).

[59] PCM Products Limited, (n.d.). https://www.pcmproducts.net/ (accessed July 16, 2024).

[60] Axiotherm GmbH, (n.d.). https://www.axiotherm.de/ (accessed July 23, 2024).

[61] PureTemp, PureTemp LLC, PureTemp (n.d.). https://puretemp.com/ (accessed November 18, 2024).

[62] G. Simonsen, R. Ravotti, P. O'Neill, A. Stamatiou, Biobased phase change materials in energy storage and thermal management technologies, Renew. Sust. Energ. Rev. 184 (2023) 113546, https://doi.org/10.1016/j.rser.2023.113546.

[63] C. Baylis, C.A. Cruickshank, Review of bio-based phase change materials as passive thermal storage in buildings, Renew. Sust. Energ. Rev. 186 (2023) 113690, https://doi.org/10.1016/j.rser.2023.113690.

[64] Y. Huang, A. Stonehouse, C. Abyekoon, Encapsulation methods for phase change materials — a critical review, Int. J. Heat Mass Transf. 200 (2023) 123458, https://doi.org/10.1016/j.ijheatmasstransfer.2022.123458.

[65] T.E. Alam, J.S. Dhau, D.Y. Goswami, E. Stefanakos, Macroencapsulation and characterization of phase change materials for latent heat thermal energy storage systems, Appl. Energy 154 (2015) 92–101, https://doi.org/10.1016/j. apenergy.2015.04.086.

[66] N. Jose, M.R. Ravindra, Microencapsulation approaches for the development of novel thermal energy storage systems and their applications, Sol. Energy Mater. Sol. Cells 280 (2025) 113271, https://doi.org/10.1016/j.solmat.2024.113271.

[67] E. Alehoseini, S.M. Jafari, Nanoencapsulation of phase change materials (PCMs) and their applications in various fields for energy storage and management, Adv. Colloid Interf. Sci. 283 (2020) 102226, https://doi.org/10.1016/j. cis.2020.102226.

[68] C. Veerakumar, A. Sreekumar, Phase change material based cold thermal energy storage: materials, techniques and applications — a review, Int. J. Refrig. 67 (2016) 271–289, https://doi.org/10.1016/j.jrefrig.2015.12.005.

[69] J.M. Yang, J.S. Kim, The microencapsulation of calcium chloride hexahydrate as a phase-change material by using the hybrid coupler of organoalkoxysilanes, J. Appl. Polym. Sci. 135 (2018) 45821, https://doi.org/10.1002/app.45821.

[70] E.M. Shchukina, M. Graham, Z. Zheng, D.G. Shchukin, Nanoencapsulation of phase change materials for advanced thermal energy storage systems, Chem. Soc. Rev. 47 (2018) 4156–4175, https://doi.org/10.1039/C8CS00099A.

[71] N.A.C. Sidik, T.H. Kean, H.K. Chow, A. Rajaandra, S. Rahman, J. Kaur, Performance enhancement of cold thermal energy storage system using nanofluid phase change materials: a review, Int. Commun. Heat Mass Transf. 94 (2018) 85–95, https://doi.org/10.1016/j.icheatmasstransfer.2018.03.024.

[72] H. Selvnes, Y. Allouche, R.I. Manescu, A. Hafner, Review on cold thermal energy storage applied to refrigeration systems using phase change materials, Therm. Sci. Eng. Prog. 22 (2021) 100807, https://doi.org/10.1016/j.tsep.2020.100807.

[73] X. Zhang, Q. Shi, L. Luo, Y. Fan, Q. Wang, G. Jia, Research Progress on the phase change materials for cold thermal energy storage, Energies 14 (2021) 8233, https://doi.org/10.3390/en14248233.

[74] M.Q. Wu, S. Wu, Y.F. Cai, R.Z. Wang, T.X. Li, Form-stable phase change composites: preparation, performance, and applications for thermal energy conversion, storage and management, Energy Storage Mater. 42 (2021) 380–417, https://doi.org/10.1016/j.ensm.2021.07.019.
[75] R.K. Mishra, K. Verma, V. Mishra, B. Chaudhary, A review on carbon-based phase change materials for thermal energy storage, J. Energy Storage 50 (2022) 104166, https://doi.org/10.1016/j.est.2022.104166.

[76] C. Xu, H. Zhang, G. Fang, Review on thermal conductivity improvement of phase change materials with enhanced additives for thermal energy storage, J. Energy Storage 51 (2022) 104568, https://doi.org/10.1016/j.est.2022.104568.

[77] S. Mo, K. Zhu, T. Yin, Y. Chen, Z. Cheng, Phase change characteristics of ethylene glycol solution-based nanofluids for subzero thermal energy storage, Int. J. Energy Res. 41 (2017) 81-91, https://doi.org/10.1002/er.3599.

[78] S. Ebadi, S. Humaira Tasnim, A. Abbas Aliabadi, S. Mahmud, Geometry and nanoparticle loading effects on the bio-based nano-PCM filled cylindrical thermal energy storage system, Appl. Therm. Eng. 141 (2018) 724-740, https://doi.org/10.1016/j.aplthermaleng.2018.05.091.

[79] D.S. Ezhumalai, G. Sriharan, S. Harikrishnan, Improved thermal energy storage behavior of CuO/palmitic acid composite as phase change material, Mater. Today Proc. 5 (2018) 14618-14627, https://doi.org/10.1016/j.matpr.2018.03.053.

[80] S. Harikrishnan, A.A. Roseline, S. Kalaiselvam, Preparation and thermophysical properties of water-glycerol mixture-based CuO nanofluids as PCM for cooling applications, IEEE Trans. Nanotechnol. 12 (2013) 629-635, https://doi.org/10.1109/TNANO.2013.2265753.

[81] S. Yu, S.G. Jeong, O. Chung, S. Kim, Bio-based PCM/carbon nanomaterials composites with enhanced thermal conductivity, Sol. Energy Mater. Sol. Cells 120 (2014) 549-554, https://doi.org/10.1016/j.solmat.2013.09.037.

[82] J. Wang, H. Xie, Z. Xin, Y. Li, L. Chen, Enhancing thermal conductivity of palmitic acid based phase change materials with carbon nanotubes as fillers, Sol. Energy 84 (2010) 339-344, https://doi.org/10.1016/j.solener.2009.12.004.

[83] N. Zhang, Y. Yuan, Y. Yuan, X. Cao, X. Yang, Effect of carbon nanotubes on the thermal behavior of palmitic-stearic acid eutectic mixtures as phase change materials for energy storage, Sol. Energy 110 (2014) 64-70, https://doi.org/10.1016/j.solener.2014.09.003.

[84] S. Wi, J. Seo, S.G. Jeong, S.J. Chang, Y. Kang, S. Kim, Thermal properties of shape-stabilized phase change materials using fatty acid ester and exfoliated graphite nanoplatelets for saving energy in buildings, Sol. Energy Mater. Sol. Cells 143 (2015) 168-173, https://doi.org/10.1016/j.solmat.2015.06.040.

[85] S. Sidney, M.L. Dhasan, C. Selvam, S. Harish, Experimental investigation of freezing and melting characteristics of graphene-based phase change nanocomposite for cold thermal energy storage applications, Appl. Sci. Switz. 9 (2019), https://doi.org/10.3390/app9061099.

[86] M. Nourani, N. Hamdami, J. Keramat, A. Moheb, M. Shahedi, Thermal behavior of paraffin-nano-Al₂O₃ stabilized by sodium stearoyl lactate as a stable phase change material with high thermal conductivity, Renew. Energy 88 (2016) 474-482, https://doi.org/10.1016/j.renene.2015.11.043.

[87] C. Zhang, M. Yu, Y. Fan, X. Zhang, Y. Zhao, L. Qiu, Numerical study on heat transfer enhancement of PCM using three combined methods based on heat pipe, Energy 195 (2020) 116809, https://doi.org/10.1016/j.energy.2019.116809.

[88] H. Zhang, J. Cheng, Q. Wang, D. Xiong, J. Song, Z. Tang, X. Liu, The graphite foam/erythritol composites with ultrahigh thermal conductivity for medium temperature applications, Sol. Energy Mater. Sol. Cells 230 (2021) 111135, https://doi.org/10.1016/j.solmat.2021.111135.

[89] Q. Xiao, W. Yuan, L. Li, T. Xu, Fabrication and characteristics of composite phase change material based on Ba(OH)₂-8H₂O for thermal energy storage, Sol. Energy Mater. Sol. Cells 179 (2018) 339-345, https://doi.org/10.1016/j.solmat.2017.12.032.

[90] A. Atal, Y. Wang, M. Harsha, S. Sengupta, Effect of porosity of conducting matrix on a phase change energy storage device, Int. J. Heat Mass Transf. 93 (2016) 9-16, https://doi.org/10.1016/j.ijheatmasstransfer.2015.09.033.

[91] X. Xiao, P. Zhang, M. Li, Effective thermal conductivity of open-cell metal foams impregnated with pure paraffin for latent heat storage, Int. J. Therm. Sci. 81 (2014) 94-105, https://doi.org/10.1016/j.ijthermalsci.2014.03.006.

[92] X. Huang, Y. Lin, G. Alva, G. Fang, Thermal properties and thermal conductivity enhancement of composite phase change materials using myristal alcohol/metal foam for solar thermal storage, Sol. Energy Mater. Sol. Cells 170 (2017) 68-76, https://doi.org/10.1016/j.solmat.2017.05.059.

[93] R. Cong, C. Xu, Y. Chen, F. Ran, G. Fang, Enhanced thermal conductivity of palmitic acid/copper foam composites with carbon nanotube as thermal energy storage materials, J. Energy Storage 40 (2021) 102783, https://doi.org/10.1016/j.est.2021.102783.

[94] A. Mallow, O. Abdelaziz, S. Graham, Thermal charging study of compressed expanded natural graphite/phase change material composites, Carbon 109 (2016) 495-504, https://doi.org/10.1016/j.carbon.2016.08.030.

[95] C.W. Robak, T.L. Bergman, A. Faghri, Enhancement of latent heat energy storage using embedded heat pipes, Int. J. Heat Mass Transf. 54 (2011) 3476-3484, https://doi.org/10.1016/j.ijheatmasstransfer.2011.03.038.

[96] M.F. Junaid, Z. ur Rehman, M. Cekon, J. Curpek, R. Farooq, H. Cui, I. Khan, Inorganic phase change materials in thermal energy storage: a review on perspectives and technological advances in building applications, Energy Build. 252 (2021) 111443, https://doi.org/10.1016/j.enbuild.2021.111443.

[97] N. Beaupere, U. Soupremanien, L. Zalewski, Nucleation triggering methods in supercooled phase change materials (PCM), a review, Thermochim. Acta 670 (2018) 184-201, https://doi.org/10.1016/j.tca.2018.10.009.

[98] Y. Lin, G. Alva, G. Fang, Review on thermal performances and applications of thermal energy storage systems with inorganic phase change materials, Energy 165 (2018) 685-708, https://doi.org/10.1016/j.energy.2018.09.128.

[99] L. Cong, B. Zou, A. Palacios, M.E. Navarro, G. Qiao, Y. Ding, Thickening and gelling agents for formulation of thermal energy storage materials — a critical

review, Renew. Sust. Energ. Rev. 155 (2022), https://doi.org/10.1016/j.rser.2021.111906.

[100] L. Liang, X. Chen, Preparation and thermal properties of eutectic hydrate salt phase change thermal energy storage material, Int. J. Photoenergy 2018 (2018), https://doi.org/10.1155/2018/6432047.

[101] W. Hua, X. Zhang, M.J. Muthoka, X. Han, Preparation and performance analysis of modified sodium acetate trihydrate, Materials 11 (2018), https://doi.org/10.3390/ma11061016.

[102] Q. He, S. Wang, M. Tong, Y. Liu, Experimental study on thermophysical properties of nanofluids as phase-change material (PCM) in low temperature cool storage, Energy Convers. Manag. 64 (2012) 199-205, https://doi.org/10.1016/j.enconman.2012.04.010.

[103] R. Parameshwaran, K. Deepak, R. Saravanan, S. Kalaiselvam, Preparation, thermal and rheological properties of hybrid nanocomposite phase change material for thermal energy storage, Appl. Energy 115 (2014) 320-330, https://doi.org/10.1016/j.apenergy.2013.11.029.

[104] S. Wu, D. Zhu, X. Li, H. Li, J. Lei, Thermal energy storage behavior of Al₂O₃-H₂O nanofluids, Thermochim. Acta 483 (2009) 73-77, https://doi.org/10.1016/j.tca.2008.11.006.

[105] T. Wu, N. Xie, J. Niu, J. Luo, X. Gao, Y. Fang, Z. Zhang, Preparation of a low-temperature nanofluid phase change material: MgCl₂-H₂O eutectic salt solution system with multi-walled carbon nanotubes (MWCNTs), Int. J. Refrig. 113 (2020) 136-144, https://doi.org/10.1016/j.ijrefrig.2020.02.008.

[106] J.Y. Sze, C. Mu, F. Ayachi, L. Yang, A. Romagnoli, B.K. Tay, Highly efficient nanofiller based on carboxylated graphene oxide in phase change materials for cold thermal energy storage, Energy Procedia 152 (2018) 198-203, https://doi.org/10.1016/j.egypro.2018.09.080.

[107] J.M. Munyalo, X. Zhang, X. Xu, Experimental investigation on supercooling, thermal conductivity and stability of nanofluid based composite phase change material, J. Energy Storage 17 (2018) 47-55, https://doi.org/10.1016/j.est.2018.02.006.

[108] C. Li, H. Yu, Y. Song, M. Wang, Z. Liu, A n-octadecane/hierarchically porous TiO₂ form-stable PCM for thermal energy storage, Renew. Energy 145 (2020) 1465-1473, https://doi.org/10.1016/j.renene.2019.06.070.

[109] P. Chandrasekaran, M. Cheralathan, V. Kumaresan, R. Velraj, Enhanced heat transfer characteristics of water based copper oxide nanofluid PCM (phase change material) in a spherical capsule during solidification for energy efficient cool thermal storage system, Energy 72 (2014) 636-642, https://doi.org/10.1016/j.energy.2014.05.089.

[110] Z. Khan, Z. Khan, A. Ghafoor, A review of performance enhancement of PCM based latent heat storage system within the context of materials, thermal stability and compatibility, Energy Convers. Manag. 115 (2016) 132-158, https://doi.org/10.1016/j.enconman.2016.02.045.

[111] G. Ferrer, A. Solé, C. Barreneche, I. Martorell, L.F. Cabeza, Corrosion of metal containers for use in PCM energy storage, Renew. Energy 76 (2015) 465-469, https://doi.org/10.1016/j.renene.2014.11.036.

[112] Y. Liang, H. Yang, H. Tang, J. Chen, Y. Wang, H. Cui, Influence of metal encapsulation on thermophysical properties and heat transfer in salt hydrate phase change material for air conditioning system, Sustain Energy Technol Assess 62 (2024) 103618, https://doi.org/10.1016/j.seta.2024.103618.

[113] S. Jegadheeswaran, A. Sundaramahalingam, S.D. Pohekar, High-conductivity nanomaterials for enhancing thermal performance of latent heat thermal energy storage systems, J. Therm. Anal. Calorim. 138 (2019) 1137-1166, https://doi.org/10.1007/s10973-019-08297-3.

[114] B. Eanest Jebasingh, A. Valan Arasu, A comprehensive review on latent heat and thermal conductivity of nanoparticle dispersed phase change material for low-temperature applications, Energy Storage Mater. 24 (2020) 52-74, https://doi.org/10.1016/j.ensm.2019.07.031.

[115] B. Eanest Jebasingh, A. Valan Arasu, A detailed review on heat transfer rate, supercooling, thermal stability and reliability of nanoparticle dispersed organic phase change material for low-temperature applications, Mater. Today Energy 16 (2020) 100408, https://doi.org/10.1016/j.mtener.2020.100408.

[116] G. Li, Y. Hwang, R. Radermacher, H.-H. Chun, Review of cold storage materials for subzero applications, Energy 51 (2013) 1-17, https://doi.org/10.1016/j.energy.2012.12.002.

[117] M. Mastani Joybari, F. Haghighat, J. Moffat, P. Sra, Heat and cold storage using phase change materials in domestic refrigeration systems: the state-of-the-art review, Energy Build. 106 (2015) 111-124, https://doi.org/10.1016/j.enbuild.2015.06.016.

[118] M.V. Beek, H.D. Jong, Reducing display bottle cooler energy consumption using PCM as active thermal storage, in: 15th Int. Refrig. Air Cond. Conf. Purdue, Purdue, 2014, pp. 1-10. https://docs.lib.purdue.edu/iracc/1494/.

[119] K. Azzouz, D. Leducq, D. Gobin, Enhancing the performance of household refrigerators with latent heat storage: an experimental investigation, Int. J. Refrig. 32 (2009) 1634-1644, https://doi.org/10.1016/j.ijrefrig.2009.03.012.

[120] F. Alzuwaid, Y.T. Ge, S.A. Tassou, A. Raeki, L. Gowreesunker, The novel use of phase change materials in a refrigerated display cabinet: an experimental investigation, Appl. Therm. Eng. 75 (2015) 770-778, https://doi.org/10.1016/j.aplthermaleng.2014.10.028.

[121] M.I.H. Khan, H.M.M. Afroz, Experimental investigation of performance improvement of household refrigerator using phase change material, Int. J. Air-Cond. Refrig. 21 (2013) 1350029, https://doi.org/10.1142/s2010132513500296.

[122] G. Sonnenrein, A. Elsner, E. Baumhögger, A. Morbach, K. Fieback, J. Vrabec, Reducing the power consumption of household refrigerators through the
integration of latent heat storage elements in wire-and-tube condensers, Int. J. Refrig. 51 (2015) 154–160, https://doi.org/10.1016/j.ijrefrig.2014.12.011.

[123] M.A. Ezan, E. Ozcan Doganay, F.E. Yavuz, I.H. Tavman, A numerical study on the usage of phase change material (PCM) to prolong compressor off period in a beverage cooler, Energy Convers. Manag. 142 (2017) 95–106, https://doi.org/10.1016/j.enconman.2017.03.032.

[124] O. Ghahramani Zarabad, R. Ahmadi, Employment of finned PCM container in a household refrigerator as a cold thermal energy storage system, Therm. Sci. Eng. Prog. (2018) 115–124, https://doi.org/10.1016/j.tsep.2018.06.002.

[125] A.C. Marques, G.F. Davies, J.A. Evans, G.G. Maidment, I.D. Wood, Theoretical modelling and experimental investigation of a thermal energy storage refrigerator, Energy 55 (2013) 457–465, https://doi.org/10.1016/j.energy.2013.03.091.

[126] R. Ben-Abdallah, D. Leducq, H.M. Hoang, L. Fournaison, O. Pateau, B. Ballot-Miguet, A. Delahaye, Experimental investigation of the use of PCM in an open display cabinet for energy management purposes, Energy Convers. Manag. 198 (2019) 111909, https://doi.org/10.1016/j.enconman.2019.111909.

[127] V. Martin, B. He, F. Setterwall, Direct contact PCM-water cold storage, Appl. Energy 87 (2010) 2652–2659, https://doi.org/10.1016/j.apenergy.2010.01.005.

[128] S.K.S. Boetcher, Cool thermal energy storage: water and ice to alternative phase change materials, in: Solid-Liq. Therm. Energy Storage, CRC Press, 2022.

[129] W.-M. Yan, C.-Y. Huang, K.-E. Gao, M. Amani, L.-H. Chien, A. Homayooni, Study on the performance enhancement of ice storage and melting processes in an ice-on-coil thermal energy storage system, J. Energy Storage 72 (2023) 108410, https://doi.org/10.1016/j.est.2023.108410.

[130] Climator, (n.d.). https://www.climator.com/en/ (accessed July 16, 2024).

[131] Thermofin, Thermofin (n.d.). https://thermofin.net/ (accessed July 16, 2024).

[132] Microtek, Microtek Labs (n.d.). https://www.microteklabs.com/ (accessed July 16, 2024).

[133] TEAP PCM, (n.d.). http://www.teappcm.com/ (accessed July 16, 2024).

[134] Va-Q-Tec, Va-Q-Tec (n.d.). https://www.va-q-tec.com/en/ (accessed July 16, 2024).

[135] Phase change solutions, (n.d.). https://phasechange.com/ (accessed July 16, 2024).

[136] Thermal custom packaging, (n.d.). https://www.thermalcustompackaging.com/ (accessed July 16, 2024).

[137] PCP Australia, (n.d.). https://pcpaustralia.com.au/ (accessed July 18, 2024).

[138] Apexy LLC - nParaffin, (n.d.). https://nparaffin.com/ (accessed July 18, 2024).

[139] RU Entropy - PCMGel, (n.d.). https://www.pcmgel.com/ (accessed July 18, 2024).

[140] S.G. Jeong, O. Chung, S. Yu, S. Kim, S. Kim, Improvement of the thermal properties of Bio-based PCM using exfoliated graphite nanoplatelets, Sol. Energy Mater. Sol. Cells 117 (2013) 87–92, https://doi.org/10.1016/j.solvmat.2013.05.038.

[141] L. Boussaba, S. Makhlouf, A. Foufa, G. Lefebvre, L. Royon, Vegetable fat: a low-cost bio-based phase change material for thermal energy storage in buildings, J. Build. Eng. 21 (2019) 222–229, https://doi.org/10.1016/j.jobe.2018.10.022.

[142] Scopus, (n.d.). https://www.scopus.com (accessed November 13, 2023).

[143] Web of Science, (n.d.). https://www.webofscience.com (accessed December 3, 2023).

[144] A.A. Mehrizi, H. Karimi-Maleh, M. Naddafi, F. Karimi, Application of bio-based phase change materials for effective heat management, J. Energy Storage 61 (2023) 106859, https://doi.org/10.1016/j.est.2023.106859.

[145] A. Benhorma, A. Bensenouci, M. Teggar, K.A.R. Ismail, M. Arici, E. Mezaache, A. Laouer, F.A.M. Lino, Prospects and challenges of bio-based phase change materials: an up to date review, J. Energy Storage 90 (2024) 111713, https://doi.org/10.1016/j.est.2024.111713.

[146] R. Fioretti, P. Principi, B. Copertaro, A refrigerated container envelope with a PCM (Phase Change Material) layer: experimental and theoretical investigation in a representative town in Central Italy, Energy Convers. Manag. 122 (2016) 131–141, https://doi.org/10.1016/j.enconman.2016.05.071.

[147] B. Copertaro, P. Principi, R. Fioretti, Thermal performance analysis of PCM in refrigerated container envelopes in the Italian context — numerical modeling and validation, Appl. Therm. Eng. 102 (2016) 873–881, https://doi.org/10.1016/j.applthermaleng.2016.04.050.

[148] S. Mercier, S. Villeneuve, M. Mondor, I. Uysal, Time-temperature management along the food cold chain: a review of recent developments, Compr. Rev. Food Sci. Food Saf. 16 (2017) 647–667, https://doi.org/10.1111/1541-4337.12269.

[149] J. Baffa, ASWB Engineering, Phase Change Material and Controls — Study, California, 2016.

[150] D. Yilmaz, E. Mancuhan, B. Yilmaz, Experimental investigation of PCM location in a commercial display cabinet cooled by a transcrritical CO₂ system, Int. J. Refrig. 120 (2020) 396–405, https://doi.org/10.1016/j.ijrefrig.2020.09.006.

[151] K. Azzouz, D. Leducq, D. Gobin, Performance enhancement of a household refrigerator by addition of latent heat storage, Int. J. Refrig. 31 (2008) 892–901, https://doi.org/10.1016/j.ijrefrig.2007.09.007.

[152] Cold Viking Solutions, Case Study: International Grocery Chain Freezer, n.d.

[153] Cold Viking Solutions, Thermal Energy Storage in an Ammonia Refrigerated Warehouse, n.d.

[154] A. Pirvaram, S.M. Sadrameli, L. Abdolmaleki, Energy management of a household refrigerator using eutectic environmental friendly PCMs in a cascaded condition, Energy 181 (2019) 321–330, https://doi.org/10.1016/j.energy.2019.05.129.

[155] G. Sonnenrein, E. Baumhögger, A. Elsner, K. Fieback, A. Morbach, A. Paul, J. Vrabeç, Copolymer-bound phase change materials for household refrigerating appliances: experimental investigation of power consumption, temperature

distribution and demand side management potential, Int. J. Refrig. 60 (2015) 166–173, https://doi.org/10.1016/j.ijrefrig.2015.06.030.

[156] R. Elarem, S. Mellouli, E. Abhilash, A. Jeini, Performance analysis of a household refrigerator integrating a PCM heat exchanger, Appl. Therm. Eng. 125 (2017) 1320–1333, https://doi.org/10.1016/j.applthermaleng.2017.07.113.

[157] B. Gin, M.M. Farid, P.K. Bansal, Effect of door opening and defrost cycle on a freezer with phase change panels, Energy Convers. Manag. 51 (2010) 2698–2706, https://doi.org/10.1016/j.enconman.2010.06.005.

[158] B. Gin, M.M. Farid, The use of PCM panels to improve storage condition of frozen food, J. Food Eng. 100 (2010) 372–376, https://doi.org/10.1016/j.jfoodeng.2010.04.016.

[159] E. Oró, L. Miró, M.M. Farid, L.F. Cabeza, Thermal analysis of a low temperature storage unit using phase change materials without refrigeration system, Int. J. Refrig. 35 (2012) 1709–1714, https://doi.org/10.1016/j.ijrefrig.2012.05.004.

[160] E. Oró, L. Miró, M.M. Farid, L.F. Cabeza, Improving thermal performance of freezers using phase change materials, Int. J. Refrig. 35 (2012) 984–991, https://doi.org/10.1016/j.ijrefrig.2012.01.004.

[161] I.H. Khan, H.M.M. Afroz, M.A. Karim, Effect of PCM on temperature fluctuation during the door opening of a household refrigerator, Int. J. Green Energy 14 (2017) 379–384, https://doi.org/10.1080/15435075.2016.1261705.

[162] K. Azzouz, D. Leducq, J. Guilpart, D. Gobin, Improving the energy efficiency of a vapor compression system using a phase change material, in: Proc. Sixth Workshop Ice Slurries IIRProceedings Second Conf. Phase Change Mater. Slurry PCM 2005, International Institute of Refrigeration, Yverdon-les-Bains, Switzerland, 2005, p. 12.

[163] P. Principi, R. Fioretti, B. Copertaro, Energy saving opportunities in the refrigerated transport sector through Phase Change Materials (PCMs) application, J. Phys. Conf. Ser. 923 (2017) 012043, https://doi.org/10.1088/1742-6596/923/1/012043.

[164] M. Visek, C.M. Joppolo, L. Molinaroli, A. Olivani, Advanced sequential dual evaporator domestic refrigerator/freezer: system energy optimization, Int. J. Refrig. 43 (2014) 71–79, https://doi.org/10.1016/j.ijrefrig.2014.03.001.

[165] M.G. Gado, S. Ookawara, S. Nada, H. Hassan, Performance investigation of hybrid adsorption-compression refrigeration system accompanied with phase change materials – intermittent characteristics, Int. J. Refrig. 142 (2022) 66–81, https://doi.org/10.1016/j.ijrefrig.2022.06.007.

[166] M. Imran Hossen Khan, H.M.M. Afroz, Effect of phase change material on compressor on-off cycling of a household refrigerator, Sci. Technol. Built Environ. 21 (2015) 462–468, https://doi.org/10.1080/23744731.2015.1023161.

[167] W.L. Cheng, B.J. Mei, Y.N. Liu, Y.H. Huang, X.D. Yuan, A novel household refrigerator with shape-stabilized PCM (Phase Change Material) heat storage condensers: an experimental investigation, Energy 36 (2011) 5797–5804, https://doi.org/10.1016/j.energy.2011.08.050.

[168] K. Naresh, B.D. Prasad, Experimental analysis on household refrigerator through the integration of latent heat storage elements in wire and tube condenser and pellet module at the evaporator, Int. J. Emerg. Technol. Innov. Res. 4 (2017) 403–406.

[169] Z. He, W. Guo, L. Song, P. Zhang, Techno-economic analysis of a refrigerated warehouse equipped with on-shelf phase change material for cold storage under different operating strategies, Energy Convers. Manag. 283 (2023) 116922, https://doi.org/10.1016/j.enconman.2023.116922.

[170] M. Rahimi, A.A. Ranjbar, M.J. Hosseini, Experimental investigation on PCM/fin slab incorporation in an evaporator side of a household refrigerator, Energy Rep. 10 (2023) 407–418, https://doi.org/10.1016/j.egyr.2023.06.053.

[171] I. Javeri-Shahreza, L. Abdolmaleki, S. Mojtaba Sadrameli, M. Fakhroleslam, Dynamic modeling and experimental validation of household refrigerators/freezers equipped with phase change materials towards improved energy efficiency, Therm. Sci. Eng. Prog. (2023) 102227, https://doi.org/10.1016/j.tsep.2023.102227.

[172] E. Alehosseini, S.M. Jafari, Micro/nano-encapsulated phase change materials (PCMs) as emerging materials for the food industry, Trends Food Sci. Technol. 91 (2019) 116–128, https://doi.org/10.1016/j.tifs.2019.07.003.

[173] K. Chen, R. Tian, J. Jiang, M. Xiao, K. Wu, Y. Kuang, P. Deng, X. Zhao, F. Jiang, Moisture loss inhibition with biopolymer films for preservation of fruits and vegetables: a review, Int. J. Biol. Macromol. 263 (2024) 130337, https://doi.org/10.1016/j.ijbiomac.2024.130337.

[174] M.J. Gidado, A.A.N. Gunny, S.C.B. Gopinath, A. Ali, C. Wongs-Aree, N.H. M. Salleh, Challenges of postharvest water loss in fruits: mechanisms, influencing factors, and effective control strategies — a comprehensive review, J. Agric. Food Res. 17 (2024) 101249, https://doi.org/10.1016/j.jafr.2024.101249.

[175] S. Rahimi-Khoigani, N. Hamdami, Effect of improved latent heat storage system on the temperature fluctuations and quality of foods, Food Control 146 (2023) 109542, https://doi.org/10.1016/j.foodcont.2022.109542.

[176] K. Xiao, Q. Liu, L. Wang, B. Zhang, W. Zhang, W. Yang, Q. Hu, F. Pei, Prediction of soluble solid content of *Agaricus bisporus* during ultrasound-assisted osmotic dehydration based on hyperspectral imaging, LWT 122 (2020) 109030, https://doi.org/10.1016/j.lwt.2020.109030.

[177] IPCC, in: Core Writing Team, R.K. Pachauri, L.A. Meyer (Eds.), Climate Change 2014: Synthesis Report, Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, IPCC, Geneva, Switzerland, 2014. https://ar5-syr.ipcc.ch/.

[178] D. Rozanna, T.G. Chuah, A. Salmiah, T.S.Y. Choong, M. Sa'ari, Fatty acids as phase change materials (PCMs) for thermal energy storage: a review, Int. J. Green Energy 1 (2005) 495–513, https://doi.org/10.1081/GE-200038722.

[179] D. Li, B. Zhuang, Y. Chen, B. Li, V. Landry, A. Kaboorani, Z. Wu, X.A. Wang, Incorporation technology of bio-based phase change materials for building