Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study
A theoretical study is conducted on laminar film condensation inside and outside the diverging/converging channels. An exact solution together with two approximate solutions are developed and compared. The rate of increment of the dimensionless film thickness is found to increase as the diverging an...
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sg-ntu-dr.10356-1543022021-12-17T00:31:22Z Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study Liu, Pengfei Ho, Jin Yao Wong, Teck Neng Toh, Kok Chuan School of Mechanical and Aerospace Engineering Engineering::Mechanical engineering Condensation Heat Transfer Enhancement Diverging/Converging Small Channels A theoretical study is conducted on laminar film condensation inside and outside the diverging/converging channels. An exact solution together with two approximate solutions are developed and compared. The rate of increment of the dimensionless film thickness is found to increase as the diverging angle increases near the inlet condensing region. A flooding effect exists due to the constricting channel diameter for condensation on converging channels. This leads to the rate of increment of the dimensionless film thickness to increase significantly near the outlet condensing region. However, the curvature effect dominates the flooding effect such that the local heat transfer coefficient increases near the outlet condensing region. A bending effect exists in the diverging/converging channels such that the linear relationship of log (hx) and log (x) fails to hold. The condensation heat transfer coefficient decreases with the increase in the diverging angle. The condensation heat transfer coefficient on both inside and outside channels can be substantially enhanced by using the converging channels. However, it deteriorates significantly when diverging channels are utilized. The surface tension and the liquid subcooling effects are also investigated. It is found that the effect of liquid subcooling is generally insignificant on condensation heat transfer. The effect of surface tension is also small in most of the cases. However, when the diverging angle approaches the critical angle, its influence becomes significant. National Research Foundation (NRF) This research is supported by National Research Foundation, Prime Minister’s Office, Singapore under its Green Data Centre Research Programme (NRF2015ENC-GDCR01001-010). 2021-12-17T00:31:22Z 2021-12-17T00:31:22Z 2020 Journal Article Liu, P., Ho, J. Y., Wong, T. N. & Toh, K. C. (2020). Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study. International Journal of Heat and Mass Transfer, 149, 119193-. https://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.119193 0017-9310 https://hdl.handle.net/10356/154302 10.1016/j.ijheatmasstransfer.2019.119193 2-s2.0-85076701426 149 119193 en NRF2015ENC-GDCR01001-010 International Journal of Heat and Mass Transfer © 2019 Elsevier Ltd. All rights reserved. |
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Engineering::Mechanical engineering Condensation Heat Transfer Enhancement Diverging/Converging Small Channels Liu, Pengfei Ho, Jin Yao Wong, Teck Neng Toh, Kok Chuan Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
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A theoretical study is conducted on laminar film condensation inside and outside the diverging/converging channels. An exact solution together with two approximate solutions are developed and compared. The rate of increment of the dimensionless film thickness is found to increase as the diverging angle increases near the inlet condensing region. A flooding effect exists due to the constricting channel diameter for condensation on converging channels. This leads to the rate of increment of the dimensionless film thickness to increase significantly near the outlet condensing region. However, the curvature effect dominates the flooding effect such that the local heat transfer coefficient increases near the outlet condensing region. A bending effect exists in the diverging/converging channels such that the linear relationship of log (hx) and log (x) fails to hold. The condensation heat transfer coefficient decreases with the increase in the diverging angle. The condensation heat transfer coefficient on both inside and outside channels can be substantially enhanced by using the converging channels. However, it deteriorates significantly when diverging channels are utilized. The surface tension and the liquid subcooling effects are also investigated. It is found that the effect of liquid subcooling is generally insignificant on condensation heat transfer. The effect of surface tension is also small in most of the cases. However, when the diverging angle approaches the critical angle, its influence becomes significant. |
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School of Mechanical and Aerospace Engineering |
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School of Mechanical and Aerospace Engineering Liu, Pengfei Ho, Jin Yao Wong, Teck Neng Toh, Kok Chuan |
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Article |
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Liu, Pengfei Ho, Jin Yao Wong, Teck Neng Toh, Kok Chuan |
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Liu, Pengfei |
title |
Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
title_short |
Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
title_full |
Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
title_fullStr |
Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
title_full_unstemmed |
Laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
title_sort |
laminar film condensation inside and outside vertical diverging/converging small channels : a theoretical study |
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2021 |
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https://hdl.handle.net/10356/154302 |
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1720447102055612416 |