Six different voltage gradients ranging from 6 to 16 V/cm were used to evaporate water from tomato samples of
9.3 (kgwater/kg drymatter) to a safer level of 2.3 (kgwater/kg dry matter). Energy efficiency decreased from100
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 b 0.05). Average energy and exergy efficiency were
found to be in the range of 67.07–85.40% and 27.75–60.34%, respectively. The electrical conductivity increased
(2.36–12.38 S/m)with a decrease inmoisture content and voltage gradient up to the boiling point. Specific energy
consumption and average improvement potential decreased from 4.64 to 2.73 MJ/kg of water evaporation and
14.18–2.82 kW with increasing voltage gradient, respectively. The values of energy and exergy losses increased
from6.88 to 21.48 kWand 6.81–21.47 kW, respectively, as the voltage gradient and moisture content decreased.
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 thewall insulation.However there is limited information on the exergy analysis
of ohmic processes and systems, to the best of the authors’ knowledge. Exergy analysis becomesmore 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.
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