Experimental and numerical investigations on radiant floor heating system integrated with macro-encapsulated phase change material

Macro-encapsulated phase change material (PCM) with PCM as core and polymer as shell is reported an extremely stable energy storage medium in radiant floor heating system (RFHS). Herein, RFHS-based rooms with and without macro-encapsulated PCM are built, and the comfort and economy of the corresponding rooms are evaluated. Experimental results show that the room with macro-encapsulated PCM has longer thermal comfort time and slighter temperature deviation than without, according to the comfort standard. Then, a 3D unsteady heat transfer model is established and corrected by experimental data. Results show that macro-encapsulated PCM as temperature buffer layer regulates the heating-cooling rate of room and forms a semi-elliptic air radiant temperature zone. The room with macro-encapsulated PCM has lower daily electricity cost (c) of 0.2595 CNY/day and higher comfort time ratio of inside air (t) of 80.88%, decreased by 36.71% and increased by 15.43% than without, respectively. The thermal conductivities of shell and core of macro-encapsulated PCM are orthogonally optimized to be respectively 0.25 and 1.00 W/(m.K), with lowest c (0.2480 CNY/day) and higher t (85.47%), decreased by 4.43% and increased by 5.67% than pre-optimization. When the ambient temperature changes within-10-10 degrees C, the input power of the room with macro-encapsulated PCM is orthogonally opti-mized to save c by 35.91%-39.39% than without.