Optimization of microwave vacuum dryer design parameters using CST microwave studio for low-moisture food application

This study presents an optimized design of a microwave vacuum dryer (MVD) for rice bran stabilization addressing the problem with uneven heat distribution leading to scorching. Primarily, this study concentrates in further optimizing dimension of the chamber, orientation of the microwave generators, material volumes, and control system parameters. Using CST Microwave Studio simulation software, it is seen that the best design for a 30-L MV chamber operating at 2.45 GHz is a cylindrical chamber with a radius of 202mm, length of 400mm, and with 2 perpendicular feeders located near the ends of the chamber. For varying material volumes (50%, 70%, & 90%), the results show that overall, the 50% yielded the highest energy field, energy distribution, and absorption rate. However, all the models yielded results that are not very far from the other models. This means that the vacuum dryer design performs well at whatever level the material container is filled at. As for the control system of an MVD for rice bran, the parameters are soon to be established. Nevertheless, this study presents an overview of initial PLC schematic diagram that is partially tested for motor control which proved that parameters can be monitored and controlled.