Thermal Energy Storage in Buildings Using PCM: Computer Simulation

This paper presents the results of phase changing material, RT20, impregnated up to 26%-wt into the gypsum wallboards to produce a significant thermal storage medium (PCMGW). A full-scale test facility using the PCMGW was monitored for two years, and was modeled using the thermal building simulation package, SUNREL, to evaluate the latent heat storage performance of the PCM treated wallboards. Measured and simulated results showed that the use of PCMGW met two needs: quick absorption of solar heat for use during off-sunshine hours and avoid overheating during sunshine hours. The PCMGWs effectively smoothed out diurnal daily fluctuations of indoor air temperatures on sunny days and, therefore, providing thermal comfort. Although the benefits of PCMGW were clearly demonstrated, it was necessary to optimize the melting point and quantity of the PCM and to highlight the importance of showing how many days the PCM could effectively minimize the indoor temperature fluctuation. In a 90-day period during summer, a PCM of with a melting range of 18 °C – 22 °C could be fully utilized for 39% and partially utilized for 55.5% of the summer days when there is either partial melting or partial freezing. There is no benefit for only 5.5% of the summer days when the PCM remains either in the solid or liquid state. These percentages show that the decision of using 26%-wt RT20 with the melting range of 18–22 °C is a practical and realistic one.