Experimental Study on the Heat Transfer Performance of a New Active-Passive Heating System Integrated Solar Concentrators and "Tri-Layer" Structural PCM Walls

The solar heat storage capacity of the wall interior was much lower in passive Chinese solar greenhouse, due to the limited heat transfer performance of building materials and the thermal-stable layer inside the wall. Based on GH-20 PCMs and the multi-surface trough solar concentrator developed by our group, a new active-passive heating system integrated solar concentrators and "tri-layer" structural PCM walls was developed to improve the heat storage capacity of the wall with the active method and passive method. In this study, the influencing factors and the influencing characteristics on heat transfer of the "tri-layer" structural PCM wall were experimentally investigated, and the optimum conditions of the TLSPCMW were recommended. The results also showed that the heating system could improve the heat storage capacity of the wall. The heat storage was 9.43MJ/m³, and the discrepancy of the heat storage and the heat release was 1.6%, while the experiment was carried out at the optimum conditions. The results can provide reference methods for increasing solar efficiency of the CSG walls, improving the indoor thermal environment and enhancing the ability to withstand outdoor low temperatures.