Computer simulation of microwave-assisted drying: Coupled influence of microwave power and pulse ratio on product and process characteristics
Jalal Dehghannya, Mahdi Habibi‐Ghods
Abstract
Shrinkage consideration is pivotal in modeling heat and mass transfer during drying processes. This study investigated the interactive effects of microwave power and pulse ratio on various properties of potato slices during drying. The drying process was further modeled using moving boundary conditions to assess the influence of these variables on heat and moisture diffusion. Results demonstrated that increasing microwave power and decreasing the pulse ratio significantly reduced drying time due to intensified effective moisture diffusion coefficient (14.28%). Enhanced product quality—evidenced by minimized shrinkage (26.28%), reduced bulk density (13.22%), and improved rehydration ratio (28.96%)—alongside increased energy efficiency, was observed with higher power levels and pulse ratios. Additionally, a higher pulse ratio intensified the electric field due to shorter microwave “on” durations, promoting a more uniform wave distribution within the product. Unlike convective air drying, where moisture removal initiated from the food's edges, the combined microwave-air drying approach exhibited a distinct moisture migration pattern attributed to the volumetric heating mechanism of microwaves, which directed heat transfer from the interior to the surface of the potato slices. The model's performance, evaluated using R 2 and RMSE metrics, was deemed satisfactory. Overall, this research highlights the importance of optimizing microwave power and pulse ratio for the efficient production of high-quality potato chips. • Joint modeling of pulsed microwave and hot-air drying was done incorporating product shrinkage. •Interaction effect of microwave power and pulse ratio on heat and moisture diffusion was assessed. •Minimized shrinkage (porous structure) was observed with higher power levels and pulse ratios. •Increased power levels and pulse ratios improved rehydration ratio and enhanced energy efficiency. • Moisture removal during the joint drying initiated from inside food, unlike the hot-air drying alone.