DEHYDRATION BEHAVIOR AND THERMODYNAMIC ANALYSIS OF KIWIFRUIT SLICES IN CONVECTIVE TRAY DRYER

Abstract

The present study was concerned with convective drying of kiwifruit slices. The influences of drying air temperature and flow rate on dehydration behavior of the samples and thermodynamic performance of the process were investigated. The results showed that the process duration was significantly decreased with the increasing temperature and flow rate. The entire dehydration process took place in the falling rate period and no constant period was observed. Using the nonlinear regression procedure, four well-known mathematical models were fitted into the experimental drying curves and the Midilli model represented the best description. The results of thermodynamic analyses indicated that, following the increment in air temperature, the energy utilization and energy utilization ratio values increased from 2.91 to 15.05 kJ s-1 and from 0.24 to 0.47, respectively. The exergy loss and exergy efficiency were specified to be in the ranges of 50-280 J s-1 and 55.89% to 84.13%, respectively. The exergy improvement potential rate and sustainability index varied from and from 12.28 J s-1 to 36.39 J s-1 and from 12.28 J s-1 to 36.39 J s-1, respectively. Generally, despite of energetic indices, higher temperatures of drying air resulted in better exergetic performance.