Performance Analysis of Solar Air Dryer for Multi Crop Drying – Effect of Varying Air Mass Flow Rate

Abstract

In India open sun crop drying is very popular technique for drying, however solar air dryers are used for crop drying in many places. The solar air dryers are designed and fabricated for a particular crop and have limited usage. The solar air dryers are available in different sizes and configurations. The solar dryer performance depends on various input parameters such as inlet temperature of the air, type of absorber material, type of configuration of solar air dryer, mass flow rate of air, overall heat transfer coefficient, solar radiation, etc. The present article discusses the effects of various parameters on the useful heat gain, instantaneous thermal efficiency of solar air dryer, temperature rise with change in mass flow rate of air, input air temperature, overall heat transfer coefficient and solar air collector area. It is observed that the optimum mass flow rate of air for maximum useful heat gain is 0.05 kg/s. Further, increase in the area will not yield any advantage for overall heat gain. The instantaneous thermal efficiency for various mass flow rates is around 88%. The overall heat transfer effect increases the instantaneous thermal efficiency up to 0.1 kg/s air mass flow rate and thereafter no significant change in the efficiency. The input air temperatures do not yield much effect on the useful heat gain and rise in temperature.

Keywords: Solar Dryer, Sun Drying, Mass Flow Rate, Solar Air Heater