Their study suggested that the dry zone traveled from the end to the center of the wood and the temperature within the wood decreased with water loss. developed a one-dimensional mathematical model to describe the transport phenomena of wood during continuous RF combined with vacuum drying. Analyzing the combined effects would assist in fully understanding the RF drying mechanism and facilitating the drying process design. Additionally, many foods are plant-based, with intracellular and intercellular water, which adds complexity to the system description. The RF drying process couples heat, mass, and electromagnetic energy conversion to heat. Therefore, the establishment of a mathematical model of RF drying performance of porous material based on multiphase simultaneous transportation is of great significance to simulate the RF drying performance on food products. Computer simulation has already been proven to be effective in predicting and optimizing parameters in RF heating processes. Compared to the experimental method, computer simulation is an economical, flexible, and intuitive way to reveal the invisible parameters of products in a complex drying process. In addition, experimental approaches have some disadvantages, such as long cycles, high economic cost, low efficiency, and operating difficulties. In RF drying experiments, it is difficult to visualize the effects of different factors on the interior of the product, such as electric field, temperature, water concentration, and water vapor concentration. The uneven distribution of temperature significantly affects the moisture distribution and ultimately affects the product quality. Various factors influence the electric field distribution and the temperature distribution in the product during RF drying, including the shape and size of the sample, electrode gaps, and the properties of materials, etc. This study reveals the mechanism of RF drying of porous media and provides an effective approach for analyzing and optimizing the RF drying process. In general, the moisture distribution in the sample affected the temperature and water vapor concentration distribution since the dielectric properties of the sample were mainly dependent on its moisture content during a drying process. The distribution of water vapor concentration in the sample was similar to that of water content distribution since a pressure gradient from center to corner allowed the mass transfer from the sample to the surrounding in the drying process. The water concentration within the food volume was non-uniform with a higher water concentration than the corner, the maximum difference of which was 0.03 g Furthermore, the temperature distribution and water vapor concentration distribution were correspondent with water distribution in the sample after RF drying. Results showed the simulation results were in agreement with experiments. Temperature history at the sample center and the heating pattern after drying was validated with experiment in a 27.12 MHz RF heating system. COMSOL Multiphysics ® package was used to establish a numerical model to simulate the heat and mass transfer process in the potato cube and solved with finite element method. To study the mechanism of heat and mass transfer in porous food material and explore its coupling effect in radio frequency (RF) drying processes, experiments were conducted with potato cubes subjected to RF drying.
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