Experimental investigation on thermal performance of porous composite phase change storage device under different operating modes and parameters

To promote the transformation from traditional heating to clean heating, the electric heat storage technology is gradually gaining attention. This study prepared a new kind of porous phase change bricks with high heat storage density and thermal conductivity, and constructed a new type of phase change storage device with multi-airflow channels for space heating. Under different operating modes and conditions, a series of experiments were conducted to analyze the heat storage/release performance, energy conversion efficiency and internal temperature distribution. When the heating power increased from 1000 W to 1400 W, the heat storage efficiency increased by 7.3% and the exergy efficiency decreased by 2.6% in Case I (heat storage mode). The rise in outlet wind speed improved the heat output capacity, yet the exergy performance varied in different modes. When the outlet wind speed increased from 0.05 m/s to 0.2 m/s, the heat release efficiency increased by 27.3% in Case II (heat release mode) and 8.3% in Case III-b (simultaneous heat storage and release mode). The exergy efficiency increased by 6.3% in Case II and dropped by 4.6% in Case III-b. In addition, the internal temperature uniformity (Sx) was mainly affected by the distribution of heat sources and airflow.