Experimental and computational fluid dynamics modeling of Satureja khuzestanica essential oil extraction during ohmic‐hydrodistillation

Abstract

AbstractA 3D computational model was presented to simulate the essential oil extraction process using ohmic‐hydrodistillation. The extraction of Satureja khuzestanica essential oil was performed at three voltages (80, 120, and 160 V) and three NaCl concentrations (0.5, 1, and 1.5% (w/v)). The effect of electrical conductivity variations with temperature and salinity concentration, the imposed electrical potential as well as evaporation‐condensation mechanisms were also taking into account. The variations of system temperature along with the amount of the extracted essential oil during the procedure were numerically calculated and good agreement with the measured experimental data was observed. The evaporation nucleation happened at two distinct locations, namely at the tips of electrodes and near the midsection at regions below the outlet tube. Increasing the NaCl concentration from 0.5 to 1.5% (w/v), led to a 10 min reduction of extraction process for 80 volts’ potential difference while the same amount of salt addition caused twice time reduction (20 min) for 160 volts’ case. Both of NaCl concentration and applied voltage parameters accelerated the extraction process. However, the effect of increasing of the system salinity was more pronounced at higher voltages.Practical applicationsThere are several methods to extract essential oils from different parts of herbs, such as hydro and steam‐distillation. However, these usual techniques have shown some drawbacks. Ohmic heating is a new thermal process that can enhance temperature of products during the passage of electric currents. This technology has many advantages including shorter process time and better energy efficiency compare to usual heating. The utilization of fluid flow and heat transfer governing equations to investigate the performance of ohmic‐hydrodistillation can help design and optimization of this process.