Evaluation of the thermal performance of an inclined solar chimney integrated with a phase change material

Abstract

A solar chimney integrated with a phase-change material (PCM) can enhance the system performance stability. An experimental study was conducted to examine the effects of the inclination angle and heat flux on the thermal performance of a solar chimney integrated using a PCM. Three inclination angles (30°, 45°, and 60°) and three heat fluxes (400 W/m2, 500 W/m2 and 600 W/m2) were used in this study. The obtained results demonstrated that the inclination angle not only affects the buoyancy effect but also affects the natural convection intensity inside the PCM. The PCM full melting times at 45° and 30° were prolonged by 6.7% and 8.6%, respectively, compared with that at 60°. In addition, the melting time was also prolonged by 16.1% and 8.0% for the 400 and 500 W/m2 heat fluxes compared with that for 600 W/m2. In contrast to the inclination angle, the heat flux exhibited a small impact on the heat transfer inside the PCM. The maximum outlet air velocities under a heat flux of 600 W/m2 were 0.25, 0.37 and 0.34 m/s for the 30°, 45° and 60° cases, respectively; and the air velocities varied slightly at 0.06, 0.1, and 0.07 m/s, respectively, for the period of phase change transition during the discharge process. Therefore, the solar chimney inclined at 45° achieved the highest airflow rate for the studied cases. The air velocity peak values at 45° during the charge process were 0.27, 0.32, and 0.37 m/s for the 400, 500, and 600 W/m2 cases, respectively. Additionally, they were relatively stable and approximately similar at 0.1 m/s for all the studied heat fluxes during the period of phase change transition in the discharge process. For practical applications, the proposed system design orientation provides an effective method for improving the system thermal performance with the least effort and cost.