Experimental investigation of optimum fin configurations for performance enhancement of solar air heaters

Abstract

This experimental study was conducted at Kasdi Merbah University in Ouargla (Algeria) to enhance the thermal performance of a flat-plate solar air heater (SAH) operating under natural convection, by optimizing fin configurations and integrating a phase change material (PCM). An experimental prototype, tilted at an angle of 33°, was thoroughly investigated across eight distinct configurations: a finless absorber plate, cylindrical fins, and triangular fins oriented either downward or upward at various inclination angles (75°, 60°, 45°, and 30°), utilizing paraffin wax as a latent heat thermal energy storage medium. The experimental results indicated that the deployment of inclined fins plays a pivotal role in augmenting heat transfer by disrupting the thermal boundary layer and inducing higher turbulence intensity within the air duct; consequently, the downward-oriented triangular fins at a 30° inclination angle yielded the highest peak instantaneous thermal efficiency of approximately 65%, followed by the 75° downward configuration at around 60%, whereas the 45° downward configuration offered the optimum compromise by providing a stable and extended output air velocity. Furthermore, the empirical data demonstrated that the integration of paraffin wax effectively sustained the delivery of heated air at a significant temperature differential for several hours after sunset, thereby confirming that coupling optimized fin geometries with latent heat storage represents a sustainable and highly efficient approach to maximizing the thermal performance and extending the operating period of solar air heaters.