Date of Publication :7th December 2016

Abstract: A forced convection Hohenheim type of solar tunnel dryer incorporated with sensible heat storage material has been developed to test its performance for drying of tomatoes under the environmental conditions of Wardha, Nagpur India. The purpose of present work is to study a forced convection (PV powered) Hohenheim STD with and without the integration of heat storage material. Thermal bricks (Cp =840J/Kg) were used as a heat storage media. Both tests have been carried out for the same mass of commodity and almost for same environmental conditions. Hourly values of global solar insolation and some meteorological data (temperature, relative humidity, wind speed etc.) have been recorded. Experiments were performed at varying mass flow rates ; varying from 0.023 to 0.038 kg/s and 0.025 to 0.036 kg/s with and without HSM. A uniform air temperature in the collector was observed with integration of heat storage material thus provides continuous drying. The Hohenheim STD with heat storage material is capable of producing an average temperature of 62.5 0C, which is suitable for dehydrating most of agro products; while an average temperature of 54.4 0C was recorded in dryer without use of heat storage media. The equilibrium moisture content for tomatoes was reached after 330 and 370 minutes when the system was used with and without heat storage material respectively. Therefore, the heat storage material reduced the drying time by 40 minutes and also increases thermal efficiency of dryer by 2.8 %. The quality of dried tomatoes in term of color, flavor, texture and time required for drying was favorable as compared to open sun drying and forced convection drying without heat storage material. However the performance of dryer can be increased by increasing loading rate and minimizing heat loss to surrounding

Reference :