Simulation and measurement of the effects of surrounding material on the uniformity of radio frequency heating of wheat flour


Miran W., Palazoğlu T. K.

Biosystems Engineering, vol.227, pp.130-146, 2023 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 227
  • Publication Date: 2023
  • Doi Number: 10.1016/j.biosystemseng.2023.02.001
  • Journal Name: Biosystems Engineering
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Communication Abstracts, Compendex, Food Science & Technology Abstracts, INSPEC, Metadex, Veterinary Science Database, DIALNET, Civil Engineering Abstracts
  • Page Numbers: pp.130-146
  • Keywords: Experimental validation, Heating rate, Heating uniformity, Low moisture foods, Modelling, Surrounding medium
  • Istanbul University Affiliated: Yes

Abstract

The objective was to numerically investigate radio frequency (RF) heating uniformity employing a high-dielectric-constant material around wheat flour placed in a rectangular container. The approach was developed to overcome the corner/edge overheating problem of rectangular objects exposed to RF field. It was hypothesised that a high-dielectric-constant material around the sample may strongly attract electric field and protect the corners and edges from overheating. This was tested by developing a multiphysics model using COMSOL. RF heating of wheat flour was simulated separately by employing air, deionised water, and NaCl solution (0.03 S m−1) in the surrounding compartments. The model was experimentally validated against temperature measurements taken at four different internal locations within the wheat flour. Root mean square error (RMSE) values were calculated for comparison and values ranging from 0.6 to 4.8 °C were obtained. Surface temperature distributions computed by the model were compared to those measured using a thermal camera. Acceptable agreement was found between the model and experimental results. It was shown by the model that a high-dielectric-constant material surrounding the sample prevents overheating of the corners and edges by deflecting the electric field away from these locations. In addition, the effect of the details in the bottom electrode design on heating uniformity was also revealed. The model proved to be useful in optimising system design and processing conditions.