Preparation and assessment of a novel hydrated salt PCM applied for intermittent floor radiant heating systems

Abstract

Intermittent floor radiant heating is widely employed in building heating systems. However, it suffers large indoor air temperature fluctuations due to its intermission. The integration of phase change material (PCM) can significantly mitigate this issue. In this study, Na2HPO4·12H2O and Na2SO4·10H2O were used as raw materials, with expanded perlite (EP) as the porous medium, to prepare a shaped composite phase change material (EPPCM). This material was then blended into mortar to produce a novel phase change mortar (EPPCM-M). Experiments were carried out to evaluate its heat storage performances. Compared to normal mortar, EPPCM-M of 25 mm thickness mitigates temperature fluctuations, with the peak temperature on the cold end reduced by about 2.5 °C and a slower cooling rate on the hot end. To assess the practical application of EPPCM in buildings, a simulation study was conducted. A room model of 4 × 4 × 3 m was built and subjected to radiant floor heating for 8 h daily, under the winter climate conditions of Shanghai from November 15th to March 14th. The results showed that the EPPCM-M can effectively suppress temperature fluctuations in both the floor surface and average indoor air temperatures. From February 27th to March 5th, the maximum fluctuation of floor surface temperature was reduced by 55.4 %, the maximum fluctuation of average indoor air temperature was reduced by 39.5 %. The application of the EPPCM-M in intermittent floor radiant heating not only ensures indoor thermal comfort but also achieves heat's “peak load shifting”, improving indoor comfort, reducing heating energy consumption, and promoting building energy efficiency.