Numerical investigation of the effect of rectangular and semicircular cavities filled with phase change materials installed on the solar wall

Abstract

The use of alternative energy sources, particularly solar energy, in buildings is rising and spreading around the globe. In this paper, a solar wall is analyzed using a numerical method. On the wall, a number of obstacles are placed in two shapes, rectangular (REC) and semicircular (SEC). The cavities are filled with organic phase-change materials. This study was performed in a 7-hour period in the absence of solar radiation on the wall for different dimensions of obstacles in 5 different modes. Various temperatures, including exhaust air temperature (TAR), Trombe wall temperature (TWL), and mean volume % of molten PCM in cavities, have been investigated. COMSOL software is used to carry out this numerical study. The results of this study showed that the use of SECs compared to RECs causes the TWL to be higher. In the most extreme case, at a 16 cm aspect ratio, the use of SECs gives a 2.1 ° C increase in TWL relative to the REC one. The outlet TAR is also increased by the usage of SECs. The use of larger dimensions of the cavities has increased the TAR leaving the wall so that the TAR after 7 hours of the absence of solar radiation, in the largest case of SECs, was more than 295.5 Kelvin. The use of SECs also increases the PCM freezing time. In the largest case of cavities, the use of SECs increases the freezing time by 15 minutes compared to RECs.