Modeling heat and mass transfer during vacuum freezing of puree droplet

A numerical simulation using COMSOL®, a commercial software, has been developed to model heat and mass transfer during vacuum freezing by evaporation of a single puree droplet. The simulations predict local water content, temperature and mass losses during the process. This theoretical model, based on the numerical resolution of heat and mass diffusion equations, includes both the process conditions and the thermophysical properties of the puree. Experimental temperature profiles and dry matter content measurements were used to validate the model and assess its accuracy. From the model, it has been shown that the main parameters that governed the transfer are the droplet diameter, the ambient pressure and the initial temperature.