Increasing the energy and exergy efficiencies of a collector using porous and recycling system

Performance of a collector in solar dryer, equipped with porous and recycling system was investigated at three airflow rates (0.009, 0.018 and 0.036 kg/s). The CFD model was applied for developing the thermal response simulation of the collector for outlet air temperature, energy and exergy parameters. The predicted and experimental data were analyzed. The results illustrated a quit good correlation between the predicted data by CFD model and experimental data. The maximum energy and exergy efficiencies were 63.4% and 22.3%, respectively, for mass flow rate of 0.009 kg/s. In general, porous and recycling system not only improved the thermal efficiency of the dryer, but also accelerated the drying time. The energy and exergy efficiencies of the collector with porous and recycling system were about 19.1% and 19.5%, respectively higher than the energy and exergy of the collector without them. The maximum total thermal energy of the collector (21.24 MJ) was produced at the airflow rate of 0.009 kg/s. No adverse effect was found on the quality of the dried products with employing of porous and recycling system in solar dryer.