Enhancement of heat transfer is very important in saving energy and protection of environment. On the other hand, heat transfer duty of heat exchangers can be improved by heat transfer enhancement techniques. In general, these techniques can be categorized into two groups of active and passive. The active techniques require external forces, e.g. electric field, acoustic or surface vibration. The passive techniques require fluid additives or special surface geometries. Electrohydrodynamic (EHD) has been used widely as an active method for enhancing heat transfer. It protects environmental issues and energy sources. The electrohydrodynamic (EHD) enhancement of heat transfers refers to the coupling of an electric field with the fluid field in a dielectric fluid medium. In this technique, either a DC or an AC high-voltage low-current electric field is applied in the dielectric field medium flowing between a charged and a receiving (grounded) electrode. Previous researches in the field of EHD augmented two-phase flow have shown that the electric field induces an additional electrical body force on the flowing fluids. One of its applications is in condensation of vapor. In this investigationcondensation of R-134a through interior pipe of a vertical double pipe condenser in presence of electric field simulated based on computational fluid dynamics (CFD) software (Comsol Multiphysics). The double pipe condenser with length of 1 meter is composed of an internal pipe with internal and external diameter of 28 mm and 31 mm and external pipe with corresponding diameter of 31 mm and 34 mm. The condenser was equipped with a concentric copper electrode at various diameters of 4, 6, 8, 12 mm. Variation of phase field, fluid temperature, condensation heat flux, electric field, dielectric permitivity and imposed electrohydrodynamic force on passing fluid through internal pipe were collected and analyzed. After validation of simulation data with experimental results, variation of R-134a condensation heat transfer coefficient versus applied voltages, saturated vapour qualities, electrode diameters and temperature differences between cold surface and the vapour, were evaluated. Simulation results show an increasing on thermal conductivity of liquid R-134a influence of electric field at different temperature. This coefficient increases by increasing the electric field strength and it decreases by increasing temperature. Also, condensation coefficient of vapour R-134a decreases by increasing operating pressure, so for the vapour with quality of 75% at pressure up to 1200 kPa decreases to 0.04, and for the vapour with quality of 100% at pressure up to 2000 kPa drops to 0.18. Simulation results shows condensation heat transfer coefficient of R-134a saturated vapor under applied voltages 2,4 and 6 kV, is higher than similar value in the absence of electric field, and it increases for higher electrode diameter. Based on this result the maximum increase of R-134a condensation heat transfer coefficient is 37.7% by using of the 12 mm electrode diameter, applying of 6 kV applied voltages, 20 Kelvin temperature difference, 1948 kPa operating pressure and flowing of 0.015 kg/s R-134a vapour. Furthermore, simulation results show switching of applied electric polarity to pipe and electrode has no effect on condensation heat transfer coefficient of R-134a. Keywords: condensation heat transfer coefficient, condensation coefficient, phase field, electrohydrodynamic force