Heat Transfer in a Large, Inclined, Flattened-Tube Steam Condenser

Abstract

Experimental results for capacity and heat transfer coefficient during steam condensation in a power-plant air-cooled condenser are presented. The condenser test section is a flattened steel tube with brazed aluminum fins. The tube is 5.7 m long with inner dimensions of 216 mm × 16 mm. The cooling air is in crossflow to the steam, with velocity at the fin inlet of 2.4–3.0 m s⁻¹. Condensation pressures range from 70–105 kPa, with the tube inclined from 0–49° downwards. Adiabatic visualization sections at the tube inlet and outlet provide identification of annular flow at the inlet and stratified flow at the outlet. Steam-side heat transfer coefficient is found to depend on wall-steam temperature difference, with minimal dependence on quality or vapor Reynolds number. As a result, steam-side heat transfer coefficient does not decrease significantly along the condenser length, as is common for smaller condenser tubes with higher mass flux. There is a slight decrease in steam-side heat transfer coefficient near the condenser outlet due to a build-up of condensate at the tube bottom. Overall condenser heat transfer coefficient is found to decrease near the condenser outlet due to an increase in the thickness of the stratified condensate layer.

Acknowledgements

The authors would like to acknowledge the technical support provided by the Air Conditioning and Refrigeration Center (ACRC) at the University of Illinois at Urbana-Champaign, and by Creative Thermal Solutions, Inc. that provided experimental apparatus, laboratory space and support and baseline air side measurements. The authors would also like to acknowledge the support provided by the TechnipFMC Educational Fund.

Additional information

Notes on contributors

William A. Davies

William Davies is currently a Ph.D. candidate in mechanical engineering at the University of Illinois at Urbana-Champaign (UIUC). He is a member of the Air Conditioning and Refrigeration Center, directed by Dr. Pega Hrnjak. His research focuses on the energy-water nexus, with a goal of reducing water use in electricity generation. Specifically, he is studying steam condensation in air-cooled condensers for power plants. In graduate school, he has been a recipient of the David Hinde Award for refrigeration research, and the TechnipFMC Educational Fund Fellowship for oil-and-gas related research. Prior to his graduate school work, he spent four years in the oil industry as a wireline field engineer for Schlumberger. He received his B.A. in Physics from Bates College in 2008 and his M.S. in mechanical engineering from UIUC in 2016.

Pega Hrnjak

Pega Hrnjak is a Stoecker Faculty Fellow Distinguished Research Professor in mechanical engineering at the University of Illinois at Urbana-Champaign, where he is also the Director of the Air Conditioning and Refrigeration Center. He is also the founder and president of Creative Thermal Solutions, Inc., a vibrant research and consulting company. His research focuses on heat transfer and fluid mechanics with end-use energy conversion applications such as refrigeration, heat pumps, and air-conditioning. He has been the recipient of many awards, including being named an ASME Fellow, an SAE Fellow, and an ASHRAE Fellow, and receiving the 2012 J&E Hall Medal, the 2011 Gustav Lorentzen Medal and the 2008 Ritter von Rittinger award. He earned his Dipl. Ing., M.S., and D.Sc. degrees in mechanical engineering from the University of Belgrade, Yugoslavia, in 1976, 1984, and 1992, respectively.