Evaluation of energy conservation potential by exhaust air recirculation for a commercial-type heated-air batch hay dryer

Energy conservation in drying and processing operations is essential in order to improve the reliability of low and moderate temperature renewable energy systems, and to reduce operating costs and energy consumption in systems using high-energy content fossil fuels in farms and processing plants especially in industrialized economies. An experimental evaluation of energy conservation potential by recirculating exhaust air in a commercial heated-air batch hay dryer is presented. The design of the exhaust recirculation unit is such that only about 30% of the total exhaust air is recirculated through the heater inlet. Experimental tests were conducted on the dryer with and without exhaust air recirculation. Maximum energy savings of 27% and 17% were achieved with exhaust air recirculation during fall and summer dryer operation, respectively.