Effect of heat insulation on the energy consumption of recirculating mixed-flow batch grain dryer

Abstract

The effects of heat insulation on the energy consumption and efficiency of a recirculating mixed-flow type grain dryer were examined.  Energy saving potential was estimated by theoretical calculations and by heat flow measurements.  Actual energy consumption was measured in two identical drying silos, only one of which was insulated.  The measurements were conducted in farm-scale dryers under practical farm working conditions.  Theoretical heat loss calculations and the heat flow measurements predicted an energy saving potential of ca. 5%–9% of the dryer heating energy.  However, the actual energy consumption measurements over three years indicated energy savings of 16%–21% for the insulated dryer compared to its uninsulated counterpart, when energy consumption per kilogram of evaporated water was considered.  It was concluded that the heat insulation eliminates the majority of heat losses in the dryer and enhances the evaporation of water, thereby improving the overall efficiency of the dryer.
Keywords: grain drying, grain dryer, energy consumption, efficiency, heat losses, heat insulation