# Thermal Behavior of Alveoli with Phase Change Materials in Fruit Packaging
## 4 Conclusions  
The search for, and implementation of, innovative technologies that help improve our daily lives is always extremely useful. Since fruit is produced in rural areas, which are sometimes a long way from the urban centers where it is sold, its proper preservation at ideal temperatures after harvesting, storage, and transport is extremely important to prevent its accelerated degradation and, thus, avoid waste, along with a reduction in energy  
Figure 14: The dimensionless temperature of fruit simulator T4 during the cooling and heating. (**a**) Cooling process. (**b**) Heating process.  
Figure 15: The dimensionless temperature of fruit simulator T5 during the cooling and heating. (**a**) Cooling process. (**b**) Heating process.  
consumption. As these issues are extremely important nowadays, an experimental study was carried out of the thermal behavior of cores with different PCMs, namely RT2 HC, RT5 HC, and RTSHC, inserted into the cores of fruit packaging, and the temperature changes in fruit simulators positioned inside the packaging were analyzed during the cooling and heating processes in a storage chamber.  
The results of the cooling tests show that the alveoli incorporated with PCM RT2 HC have the shortest cooling time, reaching the cold chamber's setpoint temperature after only 64% of the total cooling time, 8 h, compared to the 85% required for PCM RT5 HC and 72% required for PCM RTSHC. During cooling, the fruit simulators positioned closer to the periphery of the packaging were the ones that allowed for the shortest cooling times as a result of being closer to the ventilation holes in the packaging. Thus, the alveoli containing PCM RT2 HC are the most advantageous from an energy performance point of view as they allow for a shorter cooling period and, therefore, have an impact on the chamber's energy consumption.  
The subsequent tests, which consisted of a heating process to room temperature and took place with the chamber open and lasted 12 h, showed that all the fruit simulators were at a temperature of 10 \({}^{\circ}\)C after 2.5 h of testing for PCM RT2 HC, 3.4 h for PCM RTSHC and 4.4 h for PCM RTSHC. The fruit simulators positioned in the center of the package, with the alveoli filled with PCM RT5 HC, were the ones that resisted ambient conditions the longest, recording temperatures below 10 \({}^{\circ}\)C up to 8 h after the start of the test. In terms of preserving the fruit outside the chamber, subject to ambient conditions, the alveoli with PCM RTSHC showed the best results. PCM RTSHC is also better in terms of cooling time when compared to PCM RT5 HC. Therefore, it can be concluded that PCM RTSHC is the most suitable for incorporation into fruit packaging alveoli.  
Conceptualization, P.D.G. and P.D.S.; methodology, P.D.G. and P.D.S.; validation, P.D.G. and P.D.S.; formal analysis, J.L.A., P.D.G. and P.D.S.; investigation, J.L.A.; resources, P.D.G. and P.D.S.; data curation, J.L.A.; writing--original draft preparation, J.L.A., P.D.G. and P.D.S.; writing--review and editing, P.D.G. and P.D.S.; supervision, P.D.G. and P.D.S.; project administration, P.D.G.; funding acquisition, P.D.G. All authors have read and agreed to the published version of the manuscript.  
The authors would like to express their gratitude to Fundacao para a Ciencia e Tecnologia (FCT) and C-MAST (Centre for Mechanical and Aerospace Science and Technologies) for their support in the form of funding, under the project UIDB/00151/2020.  
Not applicable.  
Data Availability Statement: Data are available upon request.  
The authors declare no conflicts of interest.