Experimental and Numerical Investigations for Improvement of Building Ventilation Performance by Using Solar Chimney Integrated with Different Phase Change Materials and Nanoparticles

A detailed experimental and numerical investigation of a constructed solar chimney (SC) model and its thermal performance is presented, conducted under the climatic conditions of Al-Kut City, Iraq. This study focuses on the thermal performance of two vertical solar chimneys oriented towards the south and west directions. The first configuration consists of a building with two vertical solar chimneys, incorporating two types of phase change materials (PCMs): Al-Dura paraffin wax and block-shaped paraffin wax (PCM1) and (PCM2), respectively. These PCMs are placed in the same aluminum container, separated by partitions, and equipped with fins to enhance the thermal contact area. In the second configuration, conductive mono nanoparticles (NP), specifically aluminum oxide (Al2O3), were introduced into both (PCM1) and (PCM2) at a volume fraction of approximately 1.6% to improve the thermal characteristics of the paraffin and overall heat storage performance. The study investigates the role of paraffin wax as an energy storage medium along with nanoparticles, where the PCM stores thermal solar energy during the day and discharges it at night through the phase change process. Numerical results demonstrate that the PCMs significantly affect air change per hour (ACH) during the day and extend ventilation hours post-sunset. The second configuration showed an ACH improvement of approximately 5.35% and a reduction in room temperature by 4.7°C compared to the first case. Experimental results indicated a 5.2% improvement in ACH and a decrease of 3.9°C in room temperature. Both experimental and numerical results confirm that integrating nanofluids with PCM significantly enhances the overall efficiency of the solar chimney. The novelty of this study lies in the innovative integration of phase change materials with conductive nanoparticles, which not only enhances the thermal performance but also significantly extends ventilation periods, especially under the high solar radiation conditions typical of AL-Kut city, Iraq. Finally, due to the intense solar radiation in AL-Kut, the passive ventilation rates achieved by the solar chimney were found to be highly satisfactory.