Effect of the integration mode of phase change materials on thermal performance of radiant floor heating systems

To conduct a comparative study on the thermal performance of radiant floor heating systems (RFHS) integrated with phase change material (PCM), a 2D unsteady-state heat transfer model was developed based on CFD numerical simulations. The model includes layered, embedded, and encased PCM flooring types, with a non-PCM case introduced for comparison. The thermal state of PCM, temperature distribution of the flooring layers, spatial distribution of surface temperature, and heat flux variations were analyzed. The results indicate that an encased PCM arrangement enhances PCM utilization, maintains the floor surface temperature within the comfortable range, and is the most energy-efficient flooring combination. Its temperature fluctuation difference is 5.67 K, and its average heat flux is 110.08 W/m2. These figures represent reductions of 65.64 % and 8.93 %, respectively, compared to the non-PCM flooring. They also reductions of 51.33 % and 26.97 % compared to the layered flooring and 53.02 % and 23.29 % compared to the embedded flooring. This study can provide theoretical guidance for applying radiant floor heating systems integrated with PCM.