Optimization of the wire electrode height and pitch for 3-D electrohydrodynamic enhanced water evaporation

• Published in: International journal of heat and mass transfer Vol. 118; pp. 976 - 988
• Main Authors: Leu, Jin-Sheng, Jang, Jiin-Yuh, Wu, Yi-Hsuan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2018; Elsevier BV
• Subjects: Aerodynamics; Air flow; Computational fluid dynamics; Corona wind; EHD; Electric potential; Electrodes; Electrohydrodynamics; Evaporation; Evaporation rate; Flow equations; Forced convection; Mass transfer; Mathematical analysis; Maxwell's equations; Optimization; Power consumption; Three dimensional flow; Turbulence; Turbulent flow; Corona wind; EHD; Evaporation; Optimization
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2017.11.056

•In this study, numerical and experimental analyses were carried out to study the electrohydrodynamic (EHD) effect on the evaporation rate of a channel forced convection flow. Three-dimensional steady turbulent flow equations combined with Maxwell equations were solved. A parametric evaluation, including the flow velocity, applied voltage, and electrode location, was executed in detail. The results indicate that the EHD effect on the evaporating rate increases with increases in voltage and electrode pitch (SL) and decreases in electrode height (H).•The optimization of the electrode height (H) and longitudinal pitch (SL) was investigated numerically along with a simplified conjugate-gradient method (SCGM). The mass transfer gain per power consumption was taken as the objective function to be maximized. A search for the optimum electrode height (H) and electrode pitch (SL), ranging from 15 mm < H < 27 mm and 40 mm < SL < 100 mm, respectively, was performed for a specific applied voltage V (V0 = 13–17 kV) and inlet velocity (uin = 1.0 m/s and 1.5 m/s).The results indicated that the mass transfer gain enhanced per Watt power consumption by 316.9–179.7% when combined with the optimal design of (H, SL) at applied voltages ranging from V0 = 13 to 17 kV and uin = 1.0 m/s. In this study, numerical and experimental analyses were carried out to study the electrohydrodynamic (EHD) effect on the evaporation rate of a channel forced convection flow. Three-dimensional steady turbulent flow equations combined with Maxwell equations were solved. The optimization of the electrode height (H) and longitudinal pitch (SL) was investigated numerically along with an optimal strategy (SCGM, simplified conjugate-gradient method). The mass transfer gain per power consumption was taken as the objective function to be maximized. The results showed that the EHD effect on the evaporating rate increased with increases in applied voltage and electrode pitch (SL) and decreases in electrode height (H). For example, as air flow inlet velocity uin = 1 m/s and applied voltage V0 = 15 kV, the mass transfer enhancement was doubled for SL = 40–100 mm at H = 20 mm, while the mass transfer enhancement was 3.5 times greater for H = 30–15 mm at SL = 100 mm. In addition, the optimization analysis indicated that the mass transfer gain enhanced per Watt power consumption by 316.9–179.7% when combined with the optimal (H, SL) design ranging from V0 = 13 to 17 kV and uin = 1.0 m/s. The comparisons of numerical results and experimental data obtained satisfactory consistency within a discrepancy of 19%.