Enhancing the drying efficiency of okra using innovative microwave energy technology

¹ Department of Mechanical Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom, Thailand
² Department of Mechanical Engineering, Faculty of Engineering, Thammasat University, Pathumthani, Thailand

Abstract

Okra is widely consumed in many countries and is commonly used in various culinary applications, such as boiling, stir-frying, or consumed fresh. It can also be dried and ground into powder for medicinal purposes, such as treating diarrhea and acute inflammation. Traditional methods of preserving okra include hot air drying and sun drying. However, these methods are time-consuming, energy-intensive, and can result in the loss of nutritional value due to heat being concentrated only at the surface of the okra. Microwave energy heating is a promising alternative that can address these issues, as microwaves are capable of penetrating the surface and heating the interior of the okra before the exterior. This research developed a three-dimensional model of microwave drying applied to okra using the finite element method (FEM). Maxwell’s equations and heat transfer equations are employed to study the effects of different positions of the waveguide port and different okra arrangement patterns. The study used microwave power of 1,600 W at a frequency of 2.45 GHz and a duration of 60 s to analyze the distributions of absorbed energy, electric field, and temperature within the okra. The results indicated that positioning both waveguides on the same side of the microwave oven and arranging the okra in a double-row zigzag pattern without alternating orientations produced the most uniform distributions of absorbed energy, electric field, and temperature. These results can be applied to the microwave drying of other herbs or fruits, serving as a foundation for the future design of microwave ovens for drying.