Two-dimensional modeling and simulation of Ohmic heating processing in a two-phase food system

In this study, we modeled the simultaneous heat and electricity transfer in a solid-liquid two-phase system in order to determine the critical factors affecting the ohmic heating process. In this modeling, by considering the static fluid model of De Elwis and Fryer, a two-dimensional simulation was done by the commercial COMSOL software in order to investigate the effect of the particle size on the rate of phase heating. So, a solid particle with a lower electrical conductivity comparing with its surrounding liquid, was used to determine the ohmic heating properties of the solid-liquid mixture in two different cross-sections .The dispersed phase consisted of a cylindrical piece of potato with two different sizes and the fluid consisted of a 5% solution of carboxymethyl cellulose (CMC) at 5.0% sodium chloride. The results showed a good approximate agreement between the results of the simulation model and the experimental results. The heating rate decreased with increasing the particle size and conformed to the Worst-Case phenomenon which was used as a non-ideal circumstance in the two-dimensional simulation in the current research. The coldest point was in the center of the particle and as the time proceeded, it remained the coldest and as the distance from this point increased, the temperature increased. It can be concluded that the influence of heat and electricity throughout the heating process is faster than conventional methods of heating and occurs in both liquid and solid phase uniformly and almost with the same speed.