%0 Journal Article %A Sadek, Hossam %A Cotton, J. S. %A Ching, Chan Y. %A Shoukri, Mamdouh %D 2011 %I Begell House %K heat transfer, electrohydrodynamics, convective condensation, AC electric fields %N 2 %P 137-147 %R 10.1615/JEnhHeatTransf.v18.i2.50 %T IN-TUBE CONVECTIVE CONDENSATION UNDER AC HIGH-VOLTAGE ELECTRIC FIELDS %U https://www.dl.begellhouse.com/journals/4c8f5faa331b09ea,3a58938b34f636c7,002b8fee7aa94844.html %V 18 %X The effects of alternating high-voltage electric fields on heat transfer and pressure drop for tube-side condensation of flowing refrigerant HFC-134a have been investigated. Experiments were performed in a horizontal, single-pass, countercurrent heat exchanger with a rod electrode placed along the center of the tube. Tests were performed with a sine and square wave voltage signals over a range of frequencies, peak-to-peak voltages, and direct current (DC) offset voltage, for a fixed mass flux of 100 kg/m2s, inlet quality of 70%, and heat flux of 10 kW/m2. The heat transfer coefficient was enhanced by a factor up to 2.7 with a similar increase in the pressure drop. An increase in the DC offset voltage and/or the peak-to-peak voltage increased the effective voltage of the applied alternating current (AC) signal, with a consequent increase in both heat transfer and pressure drop. The effect of frequency on heat transfer and pressure drop is strongly influenced by the DC offset voltage and the peak-to-peak voltage of the applied signal. In general, the heat transfer enhancement and pressure drop penalty increased with an increase of frequency at the low-frequency range. The effect of frequency is less prominent as the frequency is increased and has little effect in the high-frequency range. %8 2011-04-20