Synthesis and hygrothermal properties of capric–myristic acid/diatomite-based composite phase change materials for thermal energy storage

In this paper, diatomite (DE) served as the supporting material, and capric acid–myristic acid (CA–MA) was utilized as the phase change material (PCM) to synthesize CA–MA/DE composite PCM via the vacuum impregnation method. Leak experimental results indicated that the optimal weight ratio of CA–MA was identified as 40%. The chemical compatibility, thermal properties, and stability of CA–MA/DE were evaluated. The phase temperature and latent heat of CA–MA/DE were obtained as 22.21 °C and 74.07 J g⁻¹, respectively. To study the feasibility of CA–MA/DE in energy-efficient buildings, CA–MA/DE was used to replace sand of equivalent quality to prepare the CA–MA/DE-based gypsum mortar (CA–MA/DE&GM). The results showed that the replacement rate of CA–MA/DE was determined as 30%, and the thermal properties and humidity regulation performance of CA–MA/DE&GM were significantly enhanced due to the addition of the CA–MA/DE. Notably, the digital image correlation (DIC) technique was employed to investigate the crack evolution mechanism of CA–MA/DE&GM30 (CA–MA/DE content was 30%) over 100 thermal cycles. The novel CA–MA/DE&GM30 can adjust the environmental temperature and humidity simultaneously, which has considerable potential for energy conservation in buildings.