Experimental and numerical study on thermal performance of energy storage interior wall with phase change materials

Phase change materials (PCM) and embedded tube radiant terminals demonstrate considerable advantages with respect to heat storage, energy savings, and the provision of comfort in buildings. This paper puts forth the concept of an energy storage interior wall (ESIW) with embedded pipe radiant technology, comprising PCM, and coupled with low-grade energy sources. Compared to traditional TABS, this system uses PCM energy storage to compensate for the instability of solar energy supply, which expands the application scenarios of clean energy. At the same time, it can greatly improve the thermal mass of the building and provide cooling and heating for multiple rooms. Experimental results demonstrate that the ESIW is capable of markedly enhancing the thermal comfort and indoor temperature, with an average increase of 9.9 °C relative to the outdoor. In the numerical study based on test data, sensitivity analysis was performed on 10 characteristic parameters of the ESIW structure: wall thickness, wall density, wall thermal conductivity, wall specific heat capacity, PCM phase change temperature, PCM pipe diameter, PCM enthalpy, PCM pipe length, pipe flow diameter, and number of rows of PCM pipes. The results show that the key parameters affecting the first objective (thermal storage capacity) are: pipe flow diameter, wall density, wall thickness, and PCM pipe diameter; and the key parameter affecting the second objective (investment cost) is the diameter of the PCM pipe. After multi-objective optimization for these two objectives, the thermal storage capacity of the ESIW was improved by 96.7 %, and the investment cost was reduced by 11.49 %.