Exergy and energy analyses of liquid food in an Ohmic heating process: A case study of tomato production

Abstract

Abstract Six different voltage gradients ranging from 6 to 16 V/cm were used to evaporate water from tomato samples of 9.3 (kg water/kg dry matter) to a safer level of 2.3 (kg water/kg dry matter). Energy efficiency decreased from 100 to 55.53% with decreasing moisture content and increasing voltage gradient, while, exergy efficiency increased from 3 to 83.51% with decrease in moisture content (P Industrial relevance Due to the ability of the ohmic heating technologies to achieve rapid and reasonably uniform heating of electrically conductive materials its impact on food quality is of interest. Based on literature review, in ohmic heating process it could be possible to obtain efficiencies greater than 90% in an industrial process in which these losses were controlled by the wall insulation. However there is limited information on the exergy analysis of ohmic processes and systems, to the best of the authors’ knowledge. Exergy analysis becomes more crucial, especially for the industrial (large-scale) high temperature heating applications, and it can reveal whether or not and by how much it is possible to design more efficient thermal systems by reducing the sources of existing inefficiencies. This paper deals with the performance evaluation of ohmic heating process by applying exergy analysis.