Experimental study on the performance of a stepped phase-change radiation terminal integrated with a building used in summer and winter

The rapid growth of world energy consumption and massive carbon dioxide emissions have exacerbated energy shortages and environmental pollution. It is important to put forward effective means to reduce energy consumption. In this study, paraffin was adsorbed on expanded graphite (EG) to prepare composite phase change material (CPCM), and microencapsulated phase change materials (MPCMs) were used to perform secondary apparent adsorption on the surface of CPCMs to further improve the stability and latent heat. Two kinds of composite micro-phase change materials (C-MPCM1 and C-MPCM2) with thermal conductivity of 3.78 W/(m·K) and 3.45 W/(m·K), respectively, were prepared. The C-MPCM was pressed into phase-change energy storage bricks and embedded into heating/cooling-medium coils to form a phase-change radiant floor and ceiling. The scaled-down experiments and the real-size outdoor experiments were used to verify each other and proved that the optimal water supply temperature is 17 °C in summer and 40 °C in winter. The energy consumption of the room with dual-active cascade phase change radiant terminal in the flow mode of “heating medium-floor-ceiling; refrigerant medium-ceiling-floor” is 44.79 W/m2 for cooling load in summer and 47.08 W/m2 for heat load in winter, with significant energy efficiency and comfort. The energy utilization efficiency was improved.