Experimental study of advanced phase change materials to optimise the thermal storage performance of radiant floors: Towards a low-carbon energy system for grassland pastoral settlements

Abstract

Building on the advancements in integrating phase change materials (PCM) within building envelopes to enhance thermal performance, this paper explores the use of slag cement combined with PCM to significantly improve the heat storage performance of radiant floors. The study involved the preparation of a heat storage composite mortar by mixing 0–10 % PCM into slag cement mortar using a specialized process. The thermal performance test shows that the thermal conductivity and thermal diffusivity of radiant floor decreased by 9 % and 10 % respectively with 1 % increase of PCM. Through SEM and DSC analysis, it was determined that incorporating more than 4 % PCM markedly enhances the mortar's thermal storage capacity, with 7 % identified as the optimal maximum addition. The utilization of an experimental platform within an environmental chamber to test a radiant floor module with a 5 % PCM replacement (3.26 wt%) demonstrated a 12.5 % increase in heating efficiency and a 15 min delay in peak heat flow during the exothermic process. Additionally, adding 10 % PCM increased the surface temperature of the radiant floor by 18 %, and a water supply temperature of 45 °C further elevated the surface temperature by 21 %. These findings suggest that the PCM improves the thermal insulation, the heat transfer efficiency and heat storage performance of the radiant floor, facilitates the integration of abundant renewable resources, and further integrates the system with the solar energy, thus providing a way to solve the energy-environmental balance of grassland pastoral dwellings.