Computational modelling of the impact of polystyrene containers on radio frequency heating uniformity improvement for dried soybeans

Radio frequency (RF) heating has been explored as a new method for postharvest pasteurization and disinfestations, but the non-uniform heating problem needs to be solved. In this study, an experimentally validated simulation model was developed to investigate effects of applying a surrounding polystyrene container on RF heating uniformity improvement in dried soybeans. The computer model was built for soybeans with both low and high moisture contents placed in the rectangular shaped polypropylene and polystyrene containers and heated in a parallel plate RF system. Results showed that the temperature uniformity was greatly improved by placing soybean samples in the polystyrene container other than the polypropylene one. The maximum temperature difference and uniformity index (UI) were reduced. The inner corner radius of 8 cm combined with container thickness of 8 cm could provide the best heating uniformity for soybeans. This newly developed technique can be easily implemented to improve the RF heating uniformity of other low-moisture legumes for industrial applications. Industrial relevance: Radio frequency (RF) heating has been explored as a new method for postharvest pasteurization and disinfestations of low-moisture granular legumes, but the non-uniform heating problem needs to be solved before being applied in industry. A validated simulation model was used to demonstrate the better container material and design for ensuring good temperature distributions in practical RF treatments. The optimal parameters from computer simulation may save time and reduce the cost to facilitate the design and scaling up of the RF treatment protocols. (C) 2015 Elsevier Ltd. All rights reserved.