Combined microwaves and convection heating: A conjugate approach

Abstract

Microwave treatment has been gaining increasing recognitions in the food industry and household frameworks alike. Better energy and finishing efficiencies can be obtained by adding an additional transport mechanism, such as forced air convection heating. In this work, transient distributions of temperature and moisture during the combined treatment is analyzed by a full computational fluid dynamics model, coupled with custom moisture diffusion and evaporation notations. Non-linear, interdependent transfer phenomena equations are discussed, and the multi-physics effects are emphasized. Realistic transfer exchanges are inherently considered by using a conjugate approach and no resort to empirical, averaged heat and mass transfer coefficients is made. A validation with the experimental results from the available literature has been brought forth, for potato disks drying by either pure convection, pure MW exposure or both mechanisms combined. The effect of process time and working air velocity on the local temperature distributions are finally presented.