Effects of the position and melting point of the PCM layer on the comprehensive thermal performance of a Trombe wall under mixed dry climate

PCM Trombe walls have been an effective passive technology to achieve energy efficiency. However, the majority of previous research investigated the PCM Trombe walls primarily focused on structural improvement, and very few studies have focused on mixed-dry climate Therefore, in this study, ten scenarios were created and simulated by the validated CFD model under a mixed dry climate. The findings indicate that in summer, an external PCM layer with a melting point of 38 °C could reduce the maximum peak load by 48.9 %, decrease the fluctuation amplitude by 76 %, reduce the cooling load by 14.4 %, compared to the reference case, and yields time lags of 4.5 h and 6.1 h for the maximum and minimum indoor temperatures, respectively. In winter, an external PCM layer with a melting point of 30 °C can reduce the thermal load by 38.2 %, decrease the fluctuation amplitude by 28.5 %, compared to the reference case, and achieve time lags of 4.0 h and 1.7 h for the minimal and maximum indoor temperatures, respectively. Overall, the PCM layer should be placed adjacent to the air channel, and the appropriate PCM melting points in summer and winter are different.