Experimental Study on Composite Phase Change Thermal Insulation Mortar

The insulation wall provides suitable heat for winter production of solar greenhouse. A thermal insulation mortar containing paraffin/expanded perlite composite phase change material based on desulfurized gypsum was studied as an inner insulation mortar to improve heat preservation and storage/exothermic capacities in solar greenhouse walls. Results showed that the ideal mass ratio of paraffin and expanded perlite was 60:40. The phase change temperature of the paraffin/expanded perlite composite particles was 25.3 °C, and the latent heat was 122.3 kJ/kg. The ideal mass ratio of this composite phase change material and desulfurized gypsum was 1:3. The ideal mixing amounts of dispersible polymer powder, redispersible latex powder, citric acid, hydroxypropyl methyl cellulose ether, and polypropylene fiber were 2%, 0.15%, 0.5%, and 0.5% of desulfurized gypsum content, respectively. The prepared composite phase change thermal insulation mortar had a dry density of 363 kg/m 3 , a compressive strength of 0.73 MPa, a softening coefficient of 0.65, a coefficient of thermal conductivity of 0.076 W/m·K -1 , a heat capacity of 1.35×10 3 J/kg·°C -1 , a heat storage coefficient of 11.65 W/m 2 ·K -1 , a phase change temperature of 25.6 °C, and a phase change latent heat of 89.8 kJ/kg. The phase change temperature and the phase change latent heat were suitable for solar greenhouse production.