Steam replacement strategy using microwave resonance: A future system for continuous-flow heating applications

Abstract

This study proposed the replacement of the steam heat exchanger by a novel continuous-flow microwave system. The current microwave heating system has two main drawbacks for continuous-flow applications: higher reflection losses, which reduce the effective microwave power and pose potential safety risks, and an unsteady heating rate, which leads to insufficient heating in a limited time and lower energy conversions. Therefore, we introduced the conceptual design of a novel continuous-flow microwave system for overcoming the specific drawbacks to the largest extent possible. A numerical model of this designed system was developed based on a waveguide-type cavity resonator after fully considering the properties of energy conversion and absorption. Rather than the previous systems, the combined input of waveguides on the E- and H-planes can not only improve over 20% energy utilization, but also facilitate the heating effect of the fluids. Noteworthily, the 45°-tilted waveguides can significantly reduce the reflection losses on the both input direction by enhanced microwave resonance effect, which can further promote the energy efficiency. In addition, the stub tuner was used to match impedance for reducing the application risks. Compared with the traditional steam heating methods, this novel continuous-flow microwave system with higher energy efficiency design is attractive for the dairy industry due to its outstanding electromagnetic responses and cleaner processing.