Ohmic heating of dairy fluids - Effects of local electric field on temperature distribution

Abstract

This paper presents the heat transfer model of a continuous flow ohmic heating process. The model fluid used was a mixture of reconstituted skimmed milk and whey protein concentrate solution. Two-dimensional numerical simulations of an annular ohmic heater were performed using a general purpose partial differential equation solver, FlexPDE. The momentum, energy, and electrical equations were solved for a laminar flow regime. Two models were used to determine the volumetric heating rate, one taking into account the local electric field by solving the Laplace equation while another model assumes an average voltage gradient applied between the two electrodes. Results show that while the wall temperature distribution is different for the two cases, the bulk fluid temperature and the average outlet temperature are the same. The predicted temperatures generally agree well with the measured temperatures. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.