Solar Thermal Performance: Using Perforated, Corrugated, Waved and Punched Absorber Plates
Abstract
The solar air heater's heat transfer and thermal efficiency are diminished due to the low thermal conductivity of air. Using various artificial roughness geometries has proven effective in increasing the heat contact surface area. In this study, two double-pass glazed solar heaters, equipped with perforated and corrugated absorber plates then changed to wavy and punched, are utilized. Experimental and numerical modeling are conducted to assess the effects of inlet temperature, solar intensity, and airflow rate on the outlet temperature and thermal efficiency. Thermal efficiencies significantly increase at higher flow rates, but heat loss from the absorber plate to the surroundings also becomes more pronounced at an airflow rate of 0.035 kg/s, for perforated, wavy, corrugated and punched collectors were 0.76 %, 0.62%, 0.52 %, and 0.394% respectively. However, the highest outlet temperatures were recorded at a minimum airflow rate of 0.017 kg/s, with perforated and corrugate heaters 66.7°C, 60.6°C, wave and punched heaters reaching 59.9°C and 51.8°C. Additionally, the findings reveal a notable enhancement in outlet temperature when using a perforated absorber plate, compared to corrugated, wavy, and punched absorber. Additionally, empirical formulas for thermal efficiencies and outlet temperatures were developed based on the theoretical model.