105: Computational Modeling of Multi-Layer Microwave-Convective Hybrid Dryer for Energy Efficient Drying of Temperature Sensitive Products

Introduction

The current research was focused on developing the computational model for a microwave-convective hybrid dryer to enhance drying facets such as drying time, quality of the products, and energy efficiency.

Methods

A microwave heating model was developed in COMSOL Multiphysics 6.1 and verified using existing convective-microwave experimental data. The simulated data was compared with the experimental data and were evaluated in terms of R2, root mean squared error (RSME), mean absolute error (MAE), and mean absolute percentage error (MAPE) values. The developed finite element model was used to simulate the air flow, temperature, and electric field distribution inside the drying chamber in order to optimize the novel hybrid dryer design. Notably, the “Heat Transfer in Solid and Fluids”, “Fluid Flow”, and “Electromagnetic Waves (Frequency Domain)” functions were employed in the model.

Results

In the study, it was observed that the hot air initially passes through the outlet directly but as the pressure of the drying chamber changes, air flows towards the opposite face then spreads throughout the drying space and eventually escapes through the outlet. Also, the temperature of the top wall of dryer rises quickly compared to adjacent walls. And after a few minutes, the temperature of all the wall approaches the temperature of incoming hot air. For microwave radiation at 2.45 GHz, electric field distribution was analyzed using uniformly distributed point probes throughout the cavity of different dimensions and the desired parameters (Volume max: 23630 V/m, average: 8339.06 V/m) were noticed in the medium size cavity (30.5*30.5*18.3 cm3). The performance of the model was evaluated and following values were obtained R2: 0.945, RMSE: 3.225, MAE: 2.980 and MAPE: 4.86%, indicating the robustness and accuracy of the developed model.

Significance

This study presents a cost-effective drying solution for the drying of temperature sensitive products. The results are valuable for academics, researchers, and food processing engineers working on developing energy efficient drying systems contributing to sustainable development.

Authors: Abhishek Kumar and P. Srinivasa Rao