Computer simulation model development and validation of radio frequency heating for bulk chestnuts based on single particle approach

- Simulation model was developed to improve RF heating uniformity in chestnuts.
- Temperature distributions of bulk chestnuts were simulated based on single particle.
- Corners, edges and sample contact points of chestnuts were overheated.
- RF heating uniformity was improved using separation by plastic sheets, a single layer and mixing.

A computer simulation model was developed using finite element-based commercial software, COMSOL, to simulate temperature distributions of single particle chestnuts packed in a rectangular plastic container and treated in a 6 kW, 27.12 MHz radio frequency (RF) system. The developed model was validated by temperature distributions of three horizontal layers and temperature profiles at three representative positions in the container without mixing. Both simulated and experimental results showed similar heating patterns in RF treated chestnuts under same conditions, in which corners and edges were overheated and highest temperatures were located in sample contact points of top and middle layers at four corners in the container. A heating uniformity index (HUI) was used to evaluate effects of processing conditions on RF heating uniformity. The simulated and experimental results showed that the HUI was reduced when three layers chestnuts were separated with two plastic sheets. The better heating uniformity in chestnuts was obtained when they were treated with a single layer, or under mixing conditions. The developed model can help to explore the RF heating patterns on a single particle chestnut and RF heating uniformity in chestnuts of the container, and provide valuable methods to improve the RF heating uniformity for future industrial applications.