An experimental study of a heat pipe evacuated tube solar dryer with heat recovery system

The current study designed, constructed and experimentally evaluated a heat-pipe evacuated tube solar dryer with heat a recovery system in which water was used as working and recovery fluid in the solar and dryer loops, respectively, and air was used as intermediate fluid in the dryer section. The heat recovery system was used to enhance the overall efficiency of the system and to make maximum use of solar energy intake of the dryer. The hot water in the storage tank, which is heated by the solar loop; is sent to the dryer, depending on the system requirement, and its heat in the heat exchanger is delivered to the blown air. The heated air enters the main chamber of dryer, where the drying products exist. This system was tested in the weather conditions of Sanandaj city and the obtained results indicated the effectiveness of heat recovery system. In volumetric flow rate of 0.0328 m(3)/s, the maximum outlet air temperature of dryer was approximately 44.3 degrees C. At the end of the day, the exergetic efficiency of the system reaches its maximum rate, approximately 11.7%. Using regression analysis, the most accurate equation for expressing the effectiveness of dryer was obtained. (C) 2016 Elsevier Ltd. All rights reserved.