Two-dimensional numerical simulations for the ohmic heating of whole milk solutions in an annular geometry were performed using a general-purpose partial-differential equation solver, FlexPDE software. The flow, energy, and concentration equations were developed and solved for laminar flow. The reaction kinetics model for beta-lactoglobulin proposed by Toyoda and Fryer (1996) was adopted to solve for the native, denatured, and aggregated protein concentrations in the full-flow domain. The aim of this work is to investigate how the applied voltage and flow rate affect the temperature field, and the effects on the concentration profile of each protein type in the solution. Despite what is usually expected of the ohmic heating as a uniform heating method, temperature gradients were seen to be significant from the wall to the bulk solution. The results show that a higher voltage causes a faster disappearance of native protein concentration, especially near the wall. Depending upon the applied voltage, the denatured protein concentration initially increases along the axial distance, then starts to decrease at different axial locations. The aggregated protein concentration was found to be much higher at the wall then in the bulk. In addition to describing the protein concentration distributions in the heater, the fouling tendency of the milk components on the walls is also discussed in this paper.
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