Drying and heat transfer behavior of banana undergoing combined low-pressure superheated steam and far-infrared radiation drying

The present study aimed at investigating the use of a drying system combining the concept of already proven low-pressure superheated steam drying and far-infrared radiation (LPSSD-FIR) for banana. The effects of various operating parameters, i.e., drying medium temperature and pressure, on the drying kinetics and heat transfer behavior of banana as well as the energy consumption of the process were investigated and discussed. Comparison was also made with similar sets of data obtained from the system with combined far-infrared radiation and vacuum drying (VACUUM-FIR) and the system using only low-pressure superheated steam drying (LPSSD). The results showed that LPSSD-FIR and VACUUM-FIR took shorter drying time compared to LPSSD at all drying conditions. In terms of the specific energy consumption, it was observed that the specific energy consumption of the vacuum pump was much higher than that of the far-infrared radiator or electric heater. It was also found that the specific energy consumption of LPSSD-FIR and VACUUM-FIR were lower than that of LPSSD at all drying conditions. Based on the drying rates and the specific energy consumption of all tested processes, LPSSD-FIR at 90 degrees C and 7 kPa was suggested. (c) 2007 Elsevier Ltd. All rights reserved.