Design of an auger themo-radiation dryer for drying plant-derived pomace

Abstract

This paper reports the improved model design of an auger thermo-ra-diation dryer for drying plant-deri-ved pomace under a low-temperature mode (35...80 °C) to the resulting mois-ture content at the level of 8...13 % of solids. The dryer has an adjustable speed of auger rotation (3...4 min–1), of air-flow (0.05...0.09 m/s), and is characteri-zed by the uniform distribution of heat flux. It is equipped with an energy-sav-ing two-circuit complex that utilizes sec-ondary energy to heat primary air from 21.1 °C to 28.9 °C. The use of Peltier ele-ments, installed at the heating techni-cal surface of the dryer’s auger, makes it possible to convert thermal energy into a low-voltage supply voltage for the auto-nomous supercharger and exhaust fans.The duration of pomace drying in the model structure of the auger thermo-ra-diation dryer has been determined, in particular tomato pomace, with an ini-tial content of 75 % of solids, which is 107 min. For apple pomace whose start-ing content of solids is 65 %, it is 98 min. For comparison, the duration of the con-vective drying of tomato po mace (75 % of solids) is 120 minutes. The drying was carried out at a temperature of 60 °C to the resulting moisture content of 10...12 % of solids. Organoleptic eva-luation on the example of tomato pomace confirms the effectiveness of structural solutions in the auger dryer compared to the convective technique.The results reported in this study could create conditions for the further design and implementation of the pro-posed structure of thermo-radiation dryer for drying plant-derived pomace involv-ing an altered heat supply technique and the utilization of secondary energy. The designed structure of the device makes it possible to process and preserve the quality properties of plant-derived po-mace, allowing the use of this product for a wide range of foodstuffs.