Multiphase porous media model for intermittent microwave convective drying (IMCD) of food

• A multiphase model for Intermittent Microwave Convective Drying (IMCD) has been developed.
• Fundamental understanding of the heat and mass transfer mechanism during IMCD is provided.
• Water and vapour fluxes are higher in IMCD compared to convection drying and this makes the IMCD process faster.
• Understanding of multiphase transport process will lead to an improvement in food quality and energy efficiency.

Intermittent microwave convective (IMCD) drying is an advanced drying technology that improves both energy efficiency and food quality during the drying of food materials. Despite numerous experimental studies available for IMCD, there is no complete multiphase porous media model available to describe the process. A multiphase porous media model considering liquid water, gases and the solid matrix inside the food during drying can provide in depth understanding of IMCD. In this article, firstly a multiphase porous media model was developed for IMCD. Then the model is validated against experimental data by comparing moisture content and temperature distributions after each heating and tempering periods. The profile of vapour pressures and evaporation during IMCD are presented and discussed. The relative contribution of water and vapour fluxes due to gas pressure and diffusion demonstrated that the fluxes due are relatively higher in IMCD compared to convection drying and this makes the IMCD faster.