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. 

Impact of Ohmic Heating on Electrical Conductivity and Specific Heat of Black Cumin Seed Slurry

“…The theoretical heat supplied through electricity was converted into actual heat supplied by multiplying the electricity to heat conversion efficiency of ohmic heating system. The specific heat of samples was calculated by using following equation 2 [7].…”

“…The specific heat of the slurry can be calculated by, taking the ratio of theoretical heat supplied through electricity to the actual heat supplied. With this simplifying assumption, the specific heat of slurry was determined [7]. The efficiency of ohmic heating depends on the material's ability to conduct electricity, making it the most significant parameter.…”

Modelling of Transduction Heaters Using Transformer Equivalent Circuit and Finite Element Analysis

“…Induction heating has been widely used for different applications such as heating of metals to heating of dairy fluids [1][2][3], because of its preciseness of application which satisfy these consumer demands. Electric water heaters have been the focus of several previous studies because of their pervasiveness in power systems and their consequential potential importance when considering conservation of energy through more efficient design and operation [4].…”