Performance Evaluation of Solar Air Collector by Chimney Effect for Drying Applications

Solar air collector is one of the main components of a solar dryer unit, which supplies the conditioned air for processing the perishable edible items. Various techniques have been employed to improve the thermal efficiency of the collector system, such as extended surfaces, packed beds, artificial roughness, etc., however, the cost of construction is higher. Therefore, this study was focussed on the collector efficiency enhancement using a chimney without applying the aforementioned. A single-pass solar air collector coupled with drying chamber and chimney was utilized for the experiments. The experiments were conducted in September. The average values of the solar radiation intensity, ambient temperature, temperatures inside the dryer, collector efficiency were graphically presented. The experimental data reported the maximum values of the outlet temperatures for the solar air collector with and without a chimney to be 52.8 °C and 57 °C, respectively. The collector thermal efficiency with and without the chimney was found to vary from 29.6% to 64.8% and from 26.9% to 44.8%, respectively. Furthermore, it was noticed that, with the chimney, the temperature inside the dryer showed uniform tendency.