Interaction between large deformation and moisture transport during dehydration of vegetables

Abstract

In this work, we present a multiphysics model describing heat and mass transport during drying of broccoli stalks, which is coupled to mechanical deformation. The model predicts collapse of pores due to compressive stresses during the initial stage of drying, which is later followed by reopening of pores if the liquid pressure gets under tension. This behaviour is qualitative in line with the experimental MRI observations during drying of broccoli stalk. The MRI observations show an apparent increase of moisture content in the centre of the sample during the initial stage of drying, which is consistent with the collapse of pores. In the later stages of drying, the MRI signal is prone to susceptibility effects, which can be explained by the reopened pores in the outer regions of the stalk. The purpose of this study is to show how mechanical deformation can be incorporated in a multiphysics model of drying of vegetables in a thermodynamic consistent manner. • A multiphysics model coupled with mechanical deformation was built. • The elastomeric skin can lead surprising increased moisture content. • The stress gradient can result in moisture transport against the moisture gradient.