A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins
In this paper, a theoretical model of filmwise condensation of steam on three-dimensional pin fins fabricated by selective laser melting (SLM), an additive manufacturing (AM) technique, is developed. The model considers the effects of surface tension and gravity on the liquid film flow over the pin...
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sg-ntu-dr.10356-1594772022-06-21T07:30:19Z A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins Ho, Jin Yao Liu, P. Leong, Kai Choong Wong, Teck Neng Miljkovic, Nenad School of Mechanical and Aerospace Engineering Singapore Centre for 3D Printing Engineering::Mechanical engineering Filmwise Condensation Theoretical Model In this paper, a theoretical model of filmwise condensation of steam on three-dimensional pin fins fabricated by selective laser melting (SLM), an additive manufacturing (AM) technique, is developed. The model considers the effects of surface tension and gravity on the liquid film flow over the pin fin surface. The three-dimensional nature of the liquid film flow over the fin flank and the unique features of the fin structures as a result of the laser melting process are modeled. Visualization studies are performed to verify the assumptions made in the model. From the modeling results, the local heat transfer coefficient and length-averaged heat transfer coefficient are obtained. The liquid film thickness at various locations of the pin fin is analyzed. The effects of fin tip dimensions, fin stem radius and fin pitch on the liquid film characteristics and heat transfer coefficient are systematically investigated. Our results showed that a thin film region exists in the flat and circular segments of the fin tip which cover approximately 25 – 30% of the fin surface. For a fixed fin diameter, it is found that the length-averaged heat transfer coefficient can be optimized by varying the dimensions of the flat and circular segments. A locally thin film region resulting from the suction effect is observed near the fin base for small fin spacings. However, the suction effect reduces with increasing fin spacing. Due to the three-dimensional nature of the pin fins which induces surface tension in the circumferential direction, the liquid film distribution is uniform. The differences in the length-averaged heat transfer coefficient at different circumferential locations are smaller than 5%. Finally, a comparison with existing experimental results demonstrates that a relatively accurate prediction of the average heat transfer coefficient can be achieved by our model with a maximum deviation of 8.3%. Ministry of Education (MOE) Nanyang Technological University J.Y.H. would like to acknowledge the financial support for his research appointment at the University of Illinois at Urbana-Champaign, USA under the College of Engineering (CoE) International Postdoctoral Fellowship Scholarship (IPS) provided jointly by the Ministry of Education, Singapore and Nanyang Technological University, Singapore. N.M. gratefully acknowledges funding support from the Air Conditioning and Refrigeration Center, and the International Institute for Carbon Neutral Energy Research (WPI-I2CNER), sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology. 2022-06-21T07:30:19Z 2022-06-21T07:30:19Z 2021 Journal Article Ho, J. Y., Liu, P., Leong, K. C., Wong, T. N. & Miljkovic, N. (2021). A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins. International Journal of Heat and Mass Transfer, 171, 121092-. https://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121092 0017-9310 https://hdl.handle.net/10356/159477 10.1016/j.ijheatmasstransfer.2021.121092 2-s2.0-85101106114 171 121092 en International Journal of Heat and Mass Transfer © 2021 Elsevier Ltd. All rights reserved. |
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Engineering::Mechanical engineering Filmwise Condensation Theoretical Model Ho, Jin Yao Liu, P. Leong, Kai Choong Wong, Teck Neng Miljkovic, Nenad A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
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In this paper, a theoretical model of filmwise condensation of steam on three-dimensional pin fins fabricated by selective laser melting (SLM), an additive manufacturing (AM) technique, is developed. The model considers the effects of surface tension and gravity on the liquid film flow over the pin fin surface. The three-dimensional nature of the liquid film flow over the fin flank and the unique features of the fin structures as a result of the laser melting process are modeled. Visualization studies are performed to verify the assumptions made in the model. From the modeling results, the local heat transfer coefficient and length-averaged heat transfer coefficient are obtained. The liquid film thickness at various locations of the pin fin is analyzed. The effects of fin tip dimensions, fin stem radius and fin pitch on the liquid film characteristics and heat transfer coefficient are systematically investigated. Our results showed that a thin film region exists in the flat and circular segments of the fin tip which cover approximately 25 – 30% of the fin surface. For a fixed fin diameter, it is found that the length-averaged heat transfer coefficient can be optimized by varying the dimensions of the flat and circular segments. A locally thin film region resulting from the suction effect is observed near the fin base for small fin spacings. However, the suction effect reduces with increasing fin spacing. Due to the three-dimensional nature of the pin fins which induces surface tension in the circumferential direction, the liquid film distribution is uniform. The differences in the length-averaged heat transfer coefficient at different circumferential locations are smaller than 5%. Finally, a comparison with existing experimental results demonstrates that a relatively accurate prediction of the average heat transfer coefficient can be achieved by our model with a maximum deviation of 8.3%. |
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School of Mechanical and Aerospace Engineering |
author_facet |
School of Mechanical and Aerospace Engineering Ho, Jin Yao Liu, P. Leong, Kai Choong Wong, Teck Neng Miljkovic, Nenad |
format |
Article |
author |
Ho, Jin Yao Liu, P. Leong, Kai Choong Wong, Teck Neng Miljkovic, Nenad |
author_sort |
Ho, Jin Yao |
title |
A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
title_short |
A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
title_full |
A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
title_fullStr |
A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
title_full_unstemmed |
A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
title_sort |
theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins |
publishDate |
2022 |
url |
https://hdl.handle.net/10356/159477 |
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1736856372767621120 |