Comparison Between Rectangular and Cylindrical Continuous Ohmic Heating Modelling

Elzubier Ahmed Salih; Sergey Spotar

Elzubier Ahmed Salih 1Department of Food Engineering, Faculty of Engineering and Technology, University of Gezira, Sudan
Sergey Spotar 2Department Of Chemical Engineering, Faculty of Engineering, Nottingham University, Malaysia .

Abstract

Two-dimensional models is developed for collinear cylindrical continuous ohmic heating cell
(3-ring electrode inserted in cylindrical column one at the middle and the other two at
extremities) and rectangular continuous ohmic heating (two parallel plate electrode inserted
along 0.5m long) to simulate the Electric field distribution, temperature and velocity profiles
during continuous ohmic heating of non-Newtonian power law liquid food (Guava juice) using
computational fluid dynamic (CFD) codes using A user defined functions (UDFs) which is
employed in original flat pattern FLUENT 6.1 for electric field equation. The simulation was
carried with and without buoyancy driven force effects. The buoyancy effects show significance
effect in both colliner and parallel plate electrodes configuration ohmic heating in this study, the
parallel plate electrode configuration (transverse electric fields) ohmic heating show uniform
temperature distribution than the collinear one. The computations domain used for the cylindrical
heating cell (with diameter of 0.05m and height of 0.50m, and have three electrodes, each
electrode have width of 0.02m and the distances between electrode is 0.22m) and the rectangular
heating cell (with length of 0.2m, width of 0.04m and height 0.6m, the plate electrode is
0.2m×0.04m×0.6m inserted along the wall) . In the rectangular ohmic heating the flow behavior
measurement was used to validate the CFD simulation using water in the temperature range 30-
40 0C and in the cylindrical ohmic heating for guava juice in temperature range 30-900C.