Experimental study on thermal performances of a solar chimney with and without PCM under different system inclination angles

Abstract

The thermal performance of a solar chimney was experimentally investigated to explore its effectiveness with and without phase change material (PCM) at different inclination angles (30°, 45°, and 60°). The temperature distributions of the PCM and absorbing surface and the temperature and velocity of the induced air during the entire charging and discharging process were measured and analysed. The experimental results indicated that the effect of the inclination angle on the convective heat transfer inside the PCM cannot be ignored. Compared to the 60° case, the melting times of the PCM in the 45° and 30° cases were prolonged by 3.3 % and 13.3 %, respectively, whereas the 45° case had the shortest solidification time. An inclination angle of 45° was found to be the optimal inclination, under which the solar chimney with and without the PCM reached a maximum air velocity of 0.37 and 0.4 m/s. The solar chimney integrated with PCM provided a longer ventilation duration of more than 10 h after the heat source was withdrawn. The comparative results of the chimney performance under different heat fluxes showed that the solar chimney with the PCM could work effectively even when the heat flux was as low as 200 W/m2 during the diurnal cycle operation.