Experimental study on thermal properties and thermal performance of eutectic hydrated salts/expanded perlite form-stable phase change materials for passive solar energy utilization

A novel composite phase change material (PCM) used as exterior and interior envelop materials for passive solar energy utilization was synthesized and investigated in this paper. Eutectic hydrated salt (EHS) consisted sodium carbonate decahydrate (SCD) and disodium hydrogen phosphate dodecahydrate (DHPD) with a mass ratio of 5:5 was prepared as the PCM with its phase change temperature of 26.94 °C and phase change enthalpy of 198.44 J/g while three different kinds of expanded perlites (EPs) were pretreated as supporting materials. According to the results of leakage tests and volume enthalpy, 70%EHS/EP2 was chosen as the form-stable phase change materials (FSPCM) to fabricate phase change insulation panels. The thermal conductivity with different temperature of 70%EHS/EP2 was measured and the maximum was 0.44 W/(m K) when the testing temperature was 25 °C. In addition, the heat storage and release results of 70%EHS/EP2 indicated that there was no supercooling. The thermogravimetric analysis and thermal cycling tests were performed and the results indicated that 70%EHS/EP2 had a good thermal stability and reliability. The heat transfer properties of EP panel and 70%EHS/EP2 phase change panel were tested and the results showed 70%EHS/EP2 phase change panel could remarkably decrease the maximum temperature during the melting process and obviously prolong the time of heat preservation in the cooling process which contributed to its good thermal control performance.