Computer Simulation Analyses to Improve Radio Frequency (RF) Heating Uniformity in Dried Fruits for Insect Control

摘要

An experimentally validated computer simulation model was used to investigate effects of package geometries, electrode configurations, and forced air at 60 °C on the RF heating uniformity of raisins for insect control. Higher temperatures (60-76 °C) were observed in the areas between the edges and corners in the top and bottom layers of the RF treated raisins in rectangular and cylinder shaped containers, while lower temperatures (40-52 °C) were observed at the central areas of each layer of the RF treated raisins. The heating uniformity was improved by rounding corners and reducing edges of the package geometry, modifying electrode configurations, and applying heated forced air after RF heating. About 356 min were needed to raise the raisin temperature in a rectangular geometry (25.5 × 15.0 × 10.0 cm~3) from 23 °C to 55-60 °C using only forced air treatment at 60 °C. In contrast, only 6 min of RF heating followed by 10 min of forced air at 60 °C were needed to reach a sample temperature of 55-60 °C when using electrodes with an area smaller by 2 cm than the treated sample.