Integrated Phase Change Materials (PCM) in a Hybrid Windcatcher Ventilation System

Windcatchers are widely recognized as effective passive ventilation systems. Moreover, the incorporation of fans for hybrid ventilation has been explored in research to improve windcatchers’ ventilation in low wind conditions. Nonetheless, significant limitations persist, particularly the inability to actively reduce and stabilize supply air temperatures for effective indoor cooling. Incorporating phase change materials (PCM) in windcatchers can potentially stabilize air temperatures to improve windcatchers’ cooling performance. However, this area of study remains underexplored. To address this gap, this study proposes an innovative integration of encapsulated phase change material tubes (E-PCM-T) into a four-sided solar-fan-assisted multi-directional windcatcher. The novelty lies in vertically placing E-PCM-T within the windcatcher’s airstreams, enhancing heat transfer, and addressing the challenge of low-temperature stabilisation and cooling. Using computational fluid dynamics (CFD), the study assesses how varying wind speeds, wind angles, and E-PCM-T configurations impact the windcatcher’s thermal energy storage, cooling, and overall ventilation performance in typical hot outdoor conditions, based on validated CFD models. Results indicate that E-PCM-T arrangement affects airflow, temperature reduction, and the system's cooling capacity duration. The maximum air temperature drop achieved was 2.28 °C at 1.88 m/s wind speed and a 0 ° wind angle, offering a 6.5 % temperature reduction with air temperature stabilisation for up to 7 hours. Accordingly, the impact of wind angle variation on the hybrid ventilation performance of the system was more noticeable when E-PCM-T were placed in all the airstreams. When the wind angle changed from 0 o to 30 o, with the inclusion of the solar fan, a 50 % increase in the hybrid ventilation performance was seen. Overall, the system demonstrated superior performance over traditional windcatchers in terms of thermal energy storage and cooling efficiency, while still offering adequate hybrid ventilation at 0.37 - 0.60 m/s supply air velocity range.