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Title: A theoretical analysis and parametric study of filmwise condensation on three-dimensional pin fins
Authors: Ho, Jin Yao
Liu, P.
Leong, Kai Choong
Wong, Teck Neng
Miljkovic, Nenad
Keywords: Engineering::Mechanical engineering
Issue Date: 2021
Source: 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-.
Journal: International Journal of Heat and Mass Transfer 
Abstract: 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%.
ISSN: 0017-9310
DOI: 10.1016/j.ijheatmasstransfer.2021.121092
Schools: School of Mechanical and Aerospace Engineering 
Research Centres: Singapore Centre for 3D Printing 
Rights: © 2021 Elsevier Ltd. All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
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