Heat transfer analysis of convective and microwave drying of dragon fruit

Abstract The purpose of this study was to develop a predictive three‐dimensional analytical model for predicting the temperature profile during microwave and convective drying of dragon fruit. A combined electromagnetic (Maxwell's equation) and heat transfer model was used for modeling of microwave drying. This heat transfer modeling is applicable to describe the thermal dissipation during the microwave and convective drying of agricultural produces. In this process, the dragon fruit cube of 15 mm was dried at a microwave power of 200, 400, and 600 W during the microwave drying process and hot air temperature of 60°C during the convective drying process. During microwave drying, the core or center temperature was maximum compared with the temperature at the surface of the dragon fruit cube. The predicted temperature at the center of the dragon fruit cube exposed to the microwave power of 200, 400, and 600 W for 60 s of drying time was 34.67, 44.34, and 54.02°C, respectively. In convective drying, the temperature at the edges was higher than the temperature at the center point of the dragon fruit cube. During convective drying, the fruit sample attained the maximum temperature of 60°C after being exposed to hot air for 8 min. The RMSE and values between experimental and model projected values were less than 0.988 and 0.029 in microwave drying and less than 0.891 and 0.018 in convective drying, indicating that the model projected values were in good agreement with the experimental values. Practical Applications The importance of thermal processes in deciding the safety and quality of food products is emergent. This model can predict food product temperature distribution during the hot air drying and microwave drying of Dragon fruit cubes. The economy of the drying process is often influenced by the nature and operation of these processes and hence modeling of the drying process is a crucial factor for the industry. These results can be used to quantify heat and moisture distribution, as well as to monitor the drying process of fruits and vegetables, saving energy and time.