Thesis (MScEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Measurements on air-cooled reflux steam condensers or dephlegmators at different
power plants have shown that sections of these units do not transfer heat effectively
over a range of operating conditions. The ineffective sections may be due to flooding in
the finned tubes although entrainment of condensate in certain steam inlet manifolds is
usually the main reason for the poor performance.
In this dissertation factors that limit effective dephlegmator operation are discussed and
the influence of two inlet manifold designs on dephlegmator operation is investigated.
Laboratory experiments are conducted to show under which conditions liquid
entrainment occurs and to visualize the flow distribution within the respective
manifolds.
An alternative, essentially horizontal arrangement of the dephlegmator is proposed. In
order to evaluate the performance of such a system, the heat transfer and pressure drop
on the steam-side is determined experimentally in an air-cooled finned tube. No
flooding was observed during tests conducted at zero and negative tube angles to the
horizontal. / AFRIKAANSE OPSOMMING: Toetse op lugverkoelde stoom terugvloeikondensors, of deflegmators, by verskeie
kragstasies het getoon dat sekere dele van hierdie eenhede onder verskeie
werkstoestande nie warmte effektief oordra nie. Hierdie oneffektiewe dele kan deur
vloeding van die vinbuise veroorsaak word alhoewel die meesleur van kondensaat in
sekere stoom inlaatspruitstukke gewoonlik die hoof oorsaak is.
In hierdie dissertasie word faktore wat effektiewe deflegmator werksverrigting
beinvloed bespreek en die invloed van twee inlaatspruitstukontwerpe op deflegmator
werksverrigting ondersoek. Eksperimente is in 'n laboratorium uitgevoer om aan te
toon onder watter werkstoestande vloeistof samesleping voorkom en om vloeiverdeling
binne die onderskeie inlaatspruitstukke te visualiseer.
'n Altematiewe, wesenlike horisontale deflegmator opstelling word voorgestel. Die
werksverrigting van hierdie voorstelling is ondersoek deur die warmteoordrag en
stoorn-kant drukval eksperimenteel te bepaal in 'n lugverkoelde vinbuis. Geen vloeding
is opgemerk vir toetsgevalle waar klein negatiewe of zero hoeke tot die horisontaal
ondersoek is nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51800 |
| Date | 12 1900 |
| Creators | Smit, Leslie van Zyl |
| Contributors | Kroger, D. G., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Dutch |
| Type | Thesis |
| Format | 1 v. (various pagings) : ill. |
| Rights | Stellenbosch University |
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