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Title: Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets

Abstract

This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally applied one-dimensional semi-infinite inverse heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.51 x 10-3 to 14.0 x 10-3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 670 – 6300 with a duct height of 1.106 cm and a duct width-toheight ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of a circular tube, a delta-winglet pair, and a combination of a circular tube and amore » delta-winglet pair. Comparisons of local and average heat transfer distributions for the circular tube with and without winglets are provided. Overall mean finsurface Nusselt-number results indicate a significant level of heat transfer enhancement associated with the deployment of the winglets with the circular cylinder. At the lowest Reynolds numbers (which correspond to the laminar operating conditions of existing geothermal air-cooled condensers), the enhancement level is nearly a factor of two. At higher Reynolds numbers, the enhancement level is close to 50%.« less

Authors:
;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
USDOE
OSTI Identifier:
910694
Report Number(s):
INEEL/CON-00-00084
Journal ID: ISSN 0022-1481; TRN: US200802%%71
DOE Contract Number:  
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Journal Volume: 127; Journal Issue: 2; Conference: 2000 International Mechanical Engineering Congress and Exposition,Orlando, FL,11/05/2000,11/10/2000
Country of Publication:
United States
Language:
English
Subject:
99 - GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; DUCTS; FLOW RATE; FORCED CONVECTION; HEAT EXCHANGERS; HEAT TRANSFER; MECHANICAL ENGINEERING; NUSSELT NUMBER; REYNOLDS NUMBER; TEMPERATURE DISTRIBUTION; TRANSIENTS; Finned-Tube; Heat Exchangers; heat transfer; winglets

Citation Formats

O'Brien, James Edward, and Sohal, Manohar Singh. Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets. United States: N. p., 2000. Web. doi:10.1115/1.1842786.
O'Brien, James Edward, & Sohal, Manohar Singh. Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets. United States. doi:10.1115/1.1842786.
O'Brien, James Edward, and Sohal, Manohar Singh. Wed . "Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets". United States. doi:10.1115/1.1842786. https://www.osti.gov/servlets/purl/910694.
@article{osti_910694,
title = {Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets},
author = {O'Brien, James Edward and Sohal, Manohar Singh},
abstractNote = {This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally applied one-dimensional semi-infinite inverse heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.51 x 10-3 to 14.0 x 10-3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 670 – 6300 with a duct height of 1.106 cm and a duct width-toheight ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of a circular tube, a delta-winglet pair, and a combination of a circular tube and a delta-winglet pair. Comparisons of local and average heat transfer distributions for the circular tube with and without winglets are provided. Overall mean finsurface Nusselt-number results indicate a significant level of heat transfer enhancement associated with the deployment of the winglets with the circular cylinder. At the lowest Reynolds numbers (which correspond to the laminar operating conditions of existing geothermal air-cooled condensers), the enhancement level is nearly a factor of two. At higher Reynolds numbers, the enhancement level is close to 50%.},
doi = {10.1115/1.1842786},
journal = {},
number = 2,
volume = 127,
place = {United States},
year = {Wed Nov 01 00:00:00 EST 2000},
month = {Wed Nov 01 00:00:00 EST 2000}
}

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