Investigation on rotating spiral baffles used in the solar air heater: an application of solar simulator

The thermal performance of a solar air heater equipped with novel rotating spiral-shaped baffles was experimentally investigated under controlled laboratory conditions using a solar simulator. The study evaluated the influence of mass flow rate and temperature rise parameter while maintaining constant geometric parameters of the baffle arrangement. The rotating spiral-shaped baffles enhanced fluid mixing and promoted effective heat transfer between the absorber plate and the flowing air. Compared with the conventional configuration, the modified absorber exhibited a significant increase in temperature gain and useful heat gain, with a maximum enhancement of 63.32%. The improved heat extraction also resulted in a notable reduction in absorber plate temperature, indicating superior thermal performance. Furthermore, the modified solar air heater achieved a maximum thermal efficiency of 61.03%, representing an improvement of approximately 63% over the conventional system. These findings demonstrate the effectiveness of rotating spiral-shaped baffles in enhancing the thermal performance of solar air heaters and highlight their potential for efficient solar thermal energy applications.