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Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam
Thesis (MEng) -- University of Stellenbosch, 1993.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613807512125440 |
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| access_status_str | Open Access |
| author | Groenewald, Walther |
| author2 | Kroger, D. G. |
| author_browse | Groenewald, Walther Kroger, D. G. |
| author_facet | Kroger, D. G. Groenewald, Walther |
| author_sort | Groenewald, Walther |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng) -- University of Stellenbosch, 1993. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/58003 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:42:01.161Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/58003 Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam Groenewald, Walther Kroger, D. G. Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Steam engineering Condensation Heat -- Transmission Condensers (Steam) -- Cooling Dissertations -- Mechanical engineering Thesis (MEng) -- University of Stellenbosch, 1993. The subject of the thesis is the experimental evaluation, and theoretical prediction of the heat transfer and pressure drop during the condensation of low pressure steam in an inclined, air-cooled flat-profile tube. Both co- and counter-current condensation are considered. Steam temperatures between 45°C and 60°C were considered and steam inlet Reynolds numbers varied from about 10000 to 20000. The steamside heat transfer of the tube is evaluated and shown to be bounded between two idealized heat transfer situations. These models were developed from the classical approach of laminar film condensation on a flat plate subjected to a constant heat flux, thereby approximating the actual heat transfer situation experienced during air-cooling. The theoretical models consider both annular and stratified flow and account for the logarithmic heat of the air as it flows across the condenser tube. The overall pressure change along the condenser tube is measured experimentally for both co- and counter-current condensation. Estimates of the pressure changes for these flow situations are obtained by integrating the local pressure gradient along the condenser length. The local pressure gradient is modelled from results obtained for adiabatic two-phase flow in a exact perspex replica of the actual condenser tube. These results are modified to account for the influence of heat transfer on the interfacial friction resulting from the nett flow of condensing vapour toward the vapour-liquid interface. This effect is analyzed theoretically for both laminar and turbulent vapour flow and presented in terms of a simple correlation. This correlation can easily be integrated to yield an expression in closed form for the pressure change in co-current condensation. The estimation of the pressure change in counter-current condensation requires however numerical integration due to complicated nature of the adiabatic pressure gradient correlation employed. The agreement between the prediction of these models and the experimental pressure change data is found to be excellent. Masters 2012-08-27T11:38:45Z 2012-08-27T11:38:45Z 1993 Thesis http://hdl.handle.net/10019.1/58003 en Stellenbosch University 303 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Steam engineering Condensation Heat -- Transmission Condensers (Steam) -- Cooling Dissertations -- Mechanical engineering Groenewald, Walther Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title | Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title_full | Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title_fullStr | Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title_full_unstemmed | Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title_short | Heat transfer and pressure change in an inclined air-cooled flattened tube during condensation of steam |
| title_sort | heat transfer and pressure change in an inclined air cooled flattened tube during condensation of steam |
| topic | Steam engineering Condensation Heat -- Transmission Condensers (Steam) -- Cooling Dissertations -- Mechanical engineering |
| url | http://hdl.handle.net/10019.1/58003 |
| work_keys_str_mv | AT groenewaldwalther heattransferandpressurechangeinaninclinedaircooledflattenedtubeduringcondensationofsteam |