Optimum mass percentage of microencapsulated PCM mixed with gypsum for improved latent heat storage

The present investigation aims at invalidating the idea that increasing the mass percentage of microencapsulated phase change material (mPCM) in gypsum always leads to an increase in heat absorption. This assertion is based solely on the thermophysical properties used to determinate four essential parameters that are the volumetric heat capacity, the thermal diffusivity, the thermal effusivity and the temperature range where the use of mPCM is better compared to the use of standard gypsum board. The findings show that an increase in the mPCM mass percentage in gypsum results in an improvement in heat storage when considering only volumetric heat capacity (steady-state). However, it is observed that 30% of mPCM in the composite can store more heat than 40% and 50% of mPCM when considering the thermal effusivity (dynamic state). Furthermore, it can be recommended to consider only 20% of mPCM's mass percentage, since it results in an optimal value of thermal effusivity and it yields an output very close to that of 30% of mPCM's mass percentage. In addition, increasing the mass percentage of mPCM allows a reduction of the suitable temperature range for high storage of thermal energy.