Analysis of Heat-Mass Transfer and Exergy in Heating Process of Chilled Ready-to-Eat Foods Using High-Power Microwave Ovens.

The objective of this research was to develop a 3-D coupled electromagnetics, heat transfer, and mass transfer model for transient microwave heating of chilled ready-to-eat (RTE) foods. The effect of power level, multi compartment plastic tray design, and placement angle on the temperature and moisture distributions and the rate of heating were predicted. Then, the energy and the exergy in microwave heating system were analyzed in detail. The model was validated for heating 150 g of steamed rice and 80 g of steamed chicken breast within multi compartment plastic tray for 60 s in 800 W microwave oven on a no turntable. The spatial variation of the top surface temperatures of the chilled RTE foods were captured by an infrared camera, the transient temperatures at eight locations recorded using k type thermocouple sensors. The temperature distribution during heating all showed good agreement with the simulation results. The difference rate of temperature rise (RTR) values between experimental and simulation data were 0.40°C/s-0.57°C/s (for steamed rice) and 0.07°C/s-0.42°C/s (for steamed chicken breast). Results illustrated that the developed model comprehensively explained the phenomena during the microwave heating of chilled RTE foods. The optimum study conditions had the maximum heating efficiency of 1300 W, foods in tray A1, and placement angle of 135°. Additionally, it was found that the multi compartment tray design becomes the most influencing factor to increase exergy efficiency. These findings will contribute to the development of more efficient heating protocols and improved design of microwave heating systems for RTE food applications.