The objectives of this study are (i) to determine the transient phase redistributions of a two-phase flow in a smooth horizontal annular channel by applying high voltage pulses to induce electric fields and (ii) to quantify the resultant changes in the condensation heat transfer. The experiments were performed using refrigerant R-134a flowing in the annular channel that was cooled on the outside by a counter-current flow of water. The electric fields are established by applying high voltage to a concentric rod electrode inside a grounded tube. The effect of the electrohydrodynamic (EHD) forces on the changes to the initial stratified/stratified wavy flow pattern was visualized using a high speed camera. The EHD effect results in the redistribution of the liquid–vapor phase within the channel and unique flow structures, such as twisted liquid cones and entrained droplets, are observed. These structures only appear during the initial application of EHD and are absent in the steady state. Experiments were performed using a 8 kV pulse width modulated (PWM) signal with duty cycles ranging from 0% to 100% to evaluate the heat transfer and pressure drop characteristics of the transient EHD flow patterns. The resultant heat transfer increased with the duty cycle to approximately 2.7-fold at a mass flux of 45–55 kg/m2s and 1.2-fold at a mass flux of 110 kg/m2s. The enhancement was higher as the pulse width was increased.
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September 2011
This article was originally published in
Journal of Heat Transfer
Research Papers
Transient Two-Phase Flow Patterns by Application of a High Voltage Pulse Width Modulated Signal and the Effect on Condensation Heat Transfer
Kevin Ng,
Kevin Ng
Graduate Student
Department of Mechanical Engineering,
e-mail: ngkk2@mcmaster.ca
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
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Chan Y. Ching,
Chan Y. Ching
Professor
Department of Mechanical Engineering,
e-mail: chingcy@mcmaster.ca
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
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James S. Cotton
James S. Cotton
Associate Professor
Department of Mechanical Engineering,
e-mail: cottonjs@mcmaster.ca
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
Search for other works by this author on:
Kevin Ng
Graduate Student
Department of Mechanical Engineering,
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
e-mail: ngkk2@mcmaster.ca
Chan Y. Ching
Professor
Department of Mechanical Engineering,
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
e-mail: chingcy@mcmaster.ca
James S. Cotton
Associate Professor
Department of Mechanical Engineering,
McMaster University, 1280 Main Street West, McMaster University, Hamilton
, ON, L8S 4L7, Canada
e-mail: cottonjs@mcmaster.ca
J. Heat Transfer. Sep 2011, 133(9): 091501 (10 pages)
Published Online: July 27, 2011
Article history
Received:
June 3, 2010
Revised:
March 30, 2011
Accepted:
April 1, 2011
Online:
July 27, 2011
Published:
July 27, 2011
Citation
Ng, K., Ching, C. Y., and Cotton, J. S. (July 27, 2011). "Transient Two-Phase Flow Patterns by Application of a High Voltage Pulse Width Modulated Signal and the Effect on Condensation Heat Transfer." ASME. J. Heat Transfer. September 2011; 133(9): 091501. https://doi.org/10.1115/1.4003901
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