CFD modeling and experimental validation of the thermal performance of a novel dynamic PCM Trombe wall: Comparison with the companion static wall with and without PCM

Abstract

To reduce the heat loss from the PCM Trombe wall and increase its thermal efficiency, an innovative dynamic Trombe wall incorporating a PCM layer on one face and an insulation layer on the opposite face is proposed. During the charging period of the PCM, the face containing the PCM is exposed to solar irradiation, while the face containing the insulation is exposed to the conditioned air. During the discharging period, the two faces exchange position. A large-scale model of a building unit with such a wall is constructed and tested. The model is analyzed using three-dimensional computational fluid dynamics (CFD), with generally good agreement between the two sets of results. Subsequently, CFD models of three building units are analyzed, one having the proposed dynamic wall, the other an analogous static wall, and the last one identical to the static wall but without PCM. Throughout the PCM discharging period, the temperatures of all the surfaces and the air in the conditioned space in the unit with the proposed wall are found to be consistently higher than those in the companion units. Based on energy conservation analysis, compared with the static wall, with and without PCM, the energy saving efficiency of the proposed wall is higher 25.3% and 17.5%, respectively. Similarly, its thermal efficiency is higher 79.8% and 35.4%, respectively. To achieve even higher thermal efficiency, it is shown that the thermal resistance of the glazing in the envelope, and the envelope as a whole, need to be increased by using materials with low density and heat capacity.