Utilization of Heat from Chiller in Infrared Vacuum Dryer

Abstract

       This article presents the utilization of waste heat for chiller system with the drying process in a infrared vacuum dryer. The experiments were conducted to compare the drying rate, the drying time and the energy consumption between the cases of using an infrared heat source alone and using an infrared heat source with the waste heat from a cooling water system. The temperature and the pressure of the dryer chamber were 60 ℃ and 0.1 bar, respectively. Chillies and pineapples were dried from 329% to 12% and 567% to 20% d.b., respectively. The results showed that the drying rates of both products had a similar trend. For the initial period, using of infrared heat source alone provided the higher rate of drying than the combined heat sources about 0.005 and 0.007 (kg/min). (kg water/kg [dry product) for chillies and pineapple, respectively. The drying time to obtain the final moisture content were 5 and 8 hours, respectively. The energy usage of using infrared alone were 5.56 and 8.45 kwh/kg fresh product for chillies peppers and pineapple, respectively. It can be concluded that energy usage of the combined sources was reduced to 4.8 and 7.25 kwh/kg, respectively. The waste heat from the cooling water system used in the vacuum infrared dryer can reduce the power consumption for peppers and pineapple drying about 13.9 and 14.2%, respectively.