The EHD(electrohydrodynamic) enhancement of boiling heat transfer of R123 in a vertical tube was investigated experimentally using an eccentric electrode applied both positive and negative high voltages. The results showed that the positive high voltage gave much greater enhancements and required lower average electric field strength to obtain the maximum enhancement than the negative high voltage. When positive high voltage was applied, a maximum enhancement factor of 3.7 was obtained, and it took place at the heat flux of 1.5kW/nr with average electric field strength of 1066kV/m. Whereas the maximum enhancement factor for the negative high voltage was 2.5 and it took place at the heat flux of 1.5kW/m~2 with average electric field strength of l600kV/m. The experimental phenomena are analyzed and discussed on the view of the effect of electric charge injection on electric field distribution around the heat transfer surface.
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