Abstract

The direct ohmic heating has been one of modern heating technology at which an electrical current passing directly through an electrically conductive medium generates the heat. During milk ohmic heating fouling deposits can be formed due to milk protein degradation. The fouling removal requires periodical cleaning that increases costs of energy, detergents and wastewater treatment.

Simple semiempirical generalized correlation quantifying the effect of concentration and temperature onto electrical conductivity was proposed and tested on published data of milk, coffee and aqueous H₂TiF₆ solution. The semiempirical fouling kinetics model was proposed and verified in direct batch ohmic heating of milk. The model is based on the analogy to mechanisms and chemical kinetics of serial reactions. The effect of flowrate onto the fouling formation in continuous direct ohmic heating of milk was investigated. The proposed empirical fouling kinetics model is based on the assumption that the growth rate of the fouling layer thickness depends on time exponentially. It was found that fouling layer growth intensity was not decreased by the higher wall shear stress induced by the higher flowrate. However increasing wall shear stress enlarged the maximal time tnf in which the fouling layer growth is negligible.

Submitted: February 28, 2007 · Accepted: March 16, 2007 · Published: April 21, 2007

Recommended Citation

Šulc, Radek and Nový, Michal (2007) "Semiempirical Fouling Kinetics Model in Batch and Continuous Direct Ohmic Heating of Milk," International Journal of Food Engineering: Vol. 3 : Iss. 1, Article 7.
DOI: 10.2202/1556-3758.1214
Available at: http://www.bepress.com/ijfe/vol3/iss1/art7