Application of a phase change material to a thermoelectric ceiling radiant cooling panel as a heat storage layer

The objective of this study was to propose and obtain a workable design of a phase change material integrated thermoelectric radiant cooling panel (PCM-TERCP) through numerical and experimental investigations of thermal performance. The proposed PCM-TERCP consists of thermoelectric modules (TEMs), heat sinks, insulation, and PCM layer between two aluminum panels. The PCM layer is a thermal energy storage which provides passive cooling without operation of TERCP by freezing the PCM during the operation period for shifting the electrical load to the off-peak period demand periods. A numerical model of the proposed cooling panel was developed to obtain a desirable configuration of the PCM layer such that it would maintain the surface temperature set-point of the panel during the operation period without the activation of the TEMs of the panel. The numerical model was validated by measurement and data acquired through a laboratory test of the PCM-TERCP mockup. The predicted results agreed well with the measurement data, within the 10% error bounds. A parametric study was carried out to determine the critical design parameters affecting the cooling performance of PCM-TERCP. The results indicated that the panel surface temperature was significantly affected by the number of heat fins inside the PCM and thickness of the PCM layer. A 10-mm-thick PCM layer with more than five heat fins per unit length of the panel was the most feasible solution among the several cases considered in this study for PCM-TERCP to satisfy the design requirements for application in a conditioned space. In addition, it was revealed that the liquid fraction of PCM should be under 0.6-0.65 for efficiently using the latent heat of PCM by enhancing the heat transfer of PCM.