## 3 Latent Heat Storage (LHS) Method
### Latent Heat Storage Materials (LHSMs or PCMs)
\begin{tabular}{c c c} \hline \hline
**Classification** & **Benefits** & **Drawbacks** \\ \hline \multicolumn{3}{c}{No subcooling} \\ \multicolumn{3}{c}{No supercooling} \\ \multicolumn{3}{c}{No phase segregation} \\ \multicolumn{3}{c}{Large storage capacity} \\ \multicolumn{3}{c}{High latent heat} \\ \multicolumn{3}{c}{Flammable} \\ \multicolumn{3}{c}{Recyclable substances} \\ \multicolumn{3}{c}{Certain renewable substances (_fatty_} \\ \multicolumn{3}{c}{_acids and alcohols_)} \\ \multicolumn{3}{c}{Available for all temperature range} \\ \multicolumn{3}{c}{Compatible with other materials} \\ \hline \multicolumn{3}{c}{High thermal conductivity} \\ \multicolumn{3}{c}{High latent heat} \\ \multicolumn{3}{c}{Corrosion} \\ \multicolumn{3}{c}{High storage capacity} \\ \multicolumn{3}{c}{Small volume change} \\ \multicolumn{3}{c}{Availability and low cost} \\ \hline \multicolumn{3}{c}{No segregation} \\ \multicolumn{3}{c}{High storage density} \\ \multicolumn{3}{c}{Adjustable phase transition} \\ \multicolumn{3}{c}{temperature} \\ \end{tabular}  \begin{tabular}{c} \begin{tabular}{c} \multicolumn{3}{c}{\begin{tabular}{c} \multicolumn{3}{c}{\begin{tabular}{c} \multicolumn{3}{c}{\
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From an energy consumption point of view, PCMs are widely applied in building applications (_around_ 40%) and the industrial sector (_around_ 55%). The rise of these materials will take on its full importance when raising awareness of recycling and optimizing energy consumption are the challenging tasks [85; 86]. Indeed, more and more efforts in buildings are directed to achieve comfortable conditions in terms of the living environment. These efforts remain linked to the (_high_) costs and increased use of PCMs, and they can lead to environmental pollution. In addition, controlling energy consumption appears to be an innovative way to limit energy consumption and environmental pollutants [87; 88; 89; 90; 91]. In recent years, PCMs and energy storage technologies are among the tools that have become increasingly important in buildings' energy management. In this field, [PERSON] et al. [85] discussed a fairly comprehensive literature on TES with a focus on PCMs for building applications such as cooling, heating and hybrid applications. They exhibited the active and passive processes while providing a summary of the PCMs used, their characteristics, and their incorporation techniques. Theyconcluded that the use of PCM reduces energy consumption for heating, ventilation and air conditioning in the active system as well as ceilings in the passive system; however, the main disadvantage isincomplete solidification during the night for the cooling systems. Another review on the use of PCMs for cooling building applications was carried out by [PERSON] et al. [92]. They presented and discussed several cooling applications based on PCM integration such as solar cooling systems, free cooling, evaporative and radiative cooling systems, air conditioning systems, and PCMs active and passive systems application in building envelopes. The authors dealt with the selection criteria of PCMs and concluded that the PCMs incorporation reduces energy consumption while ensuring thermal comfort and mitigating temperature fluctuations. They did, however, report many drawbacks such as low convective heat transfer coefficients, considerable portions of PCM used, incomplete cycle of the PCM solidification process at night, and limited interstitial heat transfer between the PCM and the heat transfer fluid. So, it has been claimed that active systems using paraffin can handle the problem of poor convective heat transfer. It should be noted that several studies have reported that organic solid-liquid PCMs are the most used substances where paraffin waves represent a good share (_about_ 27%) for applications as PCMs [93; 94; 82; 95]. Figure 13 exhibits the relationship between the PCMs' properties and LHS devices' performance.