Mechanisms of electrohydrodynamic flow boiling heat transfer in coaxial flow channels of dielectric refrigerant R-134a

Experimental and numerical investigations have been conducted to study the mechanisms involved in dielectric refrigerant R-134a electrohydrodynamic (EHD) flow boiling in a concentric horizontal flow channel. Numerical calculations of the electric field distribution in two-phase flow with different gas-liquid distributions and interfacial geometries in a concentric electrode arrangement are conducted by a finite element method. The experiments conducted are performed at inlet qualities from 0 to 20%, mass fluxes from 100 to 500 kg/m/sup 2/s, heat flux from 10 kW/m/sup 2/ to 20 kW/m/sup 2/ and applied voltage from 0 to 10 kV. It was found that the application of an electrohydrodynamic body force to an R-134a evaporator can result in a significant augmentation of heat transfer that may be partially explained by the numerically simulated electric field profiles near gas-liquid interfaces.