Enhanced heat transfer performance of concentrated photovoltaic system through liquid spray cooling

The Fresnel concentrated photovoltaic system uses Fresnel lenses to focus large areas of sunlight onto small areas of high-efficiency photovoltaic cells, thereby improving the photoelectric conversion efficiency. However, the high heat flux density generated by the system can easily cause component damage and place higher demands on cooling technology. Among various cooling methods, spray cooling technology stands out as one of the most promising and efficient heat dissipation techniques. This study aims to enhance heat transfer by combining spray cooling technology with enhanced surface techniques. The heat transfer mechanisms of spray cooling under both groove-type and upright-type enhanced surfaces are investigated. An experimental system was built to study the heat transfer capability of spray cooling at high heat flux. Under a high concentration ratio, temperatures can be controlled below 35°C, reflecting a 14% reduction compared to the peak temperature. The fluidity of the working medium on the surface is inversely proportional to the structure height and directly proportional to the channel width. The addition of enhanced surfaces enhances heat transfer to a certain extent due to the increased heat transfer area, while it also suppresses heat transfer due to the reduced fluidity of the working medium on the heat exchange surface. To address this dual effect, a new dimensionless parameter, α, was introduced to characterize the interplay between these factors. A dimensionless analysis method was then applied to derive heat transfer correlations for spray-enhanced cooling, providing valuable insights for engineering applications.