Thesis (Ph.D.)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The primary purpose of this dissertation is to further the understanding of the influence of
plenum chamber aerodynamic behaviour on mechanical draught air-cooled heat exchanger
(ACHE) performance. The investigation, which included both forced and induced draught
ACHEs, was conducted through the use of a commercially available computational fluid
dynamics (CFD) code. A numerical axial flow fan and heat exchanger model that simulates
the effect of the axial flow fan and heat exchanger bundle respectively on the flow field
within the ACHE was developed and included in the CFD-code through user-programming.
Where appropriate the numerical investigation was augmented with experimental data. The
plenum chamber aerodynamic behaviour is characterised and included in the draught
equations associated with forced and induced draught ACHEs through the introduction of
dimensionless plenum chamber recovery and plenum chamber loss coefficient respectively.
The influence of changes made to a range of mechanical draught ACHEs on plenum chamber
aerodynamic behaviour was investigated. These changes include:
• Operating conditions of the axial flow fan.
• The height of the plenum chamber in the fan axial direction.
• The heat exchanger bundle isothermal flow resistance.
• The fan to heat exchanger area ratio.
• The axial position of the fan in the fan casing.
From the results of the numerical investigation a set of design guidelines are set for both
forced and induced draught ACHEs. The design guidelines include recommended values for
the dimensionless plenum chamber recovery and plenum chamber loss coefficient to be used
in the respective draught equations enabling a more accurate prediction of the operating point
of a proposed mechanical draught ACHE.
KEYWORDS:
air-cooled heat exchanger
numerical investigation
plenum chamber
aerodynamic behaviour / AFRIKAANSE OPSOMMING: Die primere doel van hierdie proefskrif is om die kennis aangaande die invloed van plenum
ruimte lugdinamiese gedrag op die werking van meganiese-trek lugverkoelde warmteruilers
(LVWRs) te verbreed. Die ondersoek wat geforseerde- asook geinduseerdetrek LVWRs
ingesluit het is uitgevoer deur gebruik te maak van In kornmersiele verkrygbare
berekeningsvloeimeganika-pakket. In Numeriese aksiaalwaaier- en warmteruilermodel wat die
invloed van respektiewelik die aksiaalwaaier en die warmteruiler op die vloeiveld in die
LVWR simuleer is ontwikkel en in die berekeningsvloeimeganika-pakket geinkorporeer
d.m.v gebruikers-roetines. Waar van toepassing is die numeriese ondersoek aangevul met
eksperimentele data. Die plenumruimte lugdinamiese gedrag word gekarakteriseer en
ingesluit in die onderskeie trekvergelykings vir geforseerde- en geiduseerde-trek LVWRs
deur die daarstelling van In dimensielose plenumruimteherwinnings- en plenumruimteverlieskoeffisient.
Die invloed van veranderinge wat aangebring is aan In reeks meganiesetrek
LVWRs op die plenumruimte lugdinamiese gedrag is ondersoek. Hierdie veranderinge
sluit die volgende in:
• Die werking van die aksiaalwaaier.
• Die hoogte van die plenumruimte in die aksiale rigting van die waaier.
• Die isotermiese lugweerstand van die warmteruiler.
• Die waaier-tot-warmteruiler area-verhouding.
• Die aksiale posisie van die aksiaalwaaier in die waaierring.
In Stel ontwerpsriglyne Vir beide geforseerde- en geinduseerde-trek LVWRs word
geformuleer gebaseer op die resultate van die numeriese ondersoek. Die ontwerpsriglyne sluit
aanbevole waardes vir die dimensielose plenumruimte-herwinnings- en plenumruimteverlieskoeffisient
in wat op hulle beurt aangewend kan word om In meer akkurate aanduiding
van die werkspunt van In beplande LVWR te bereken deur gebruik te maak van die toepaslike
trekvergelyking.
SLEUTEL WQORDE:
lugverkoelde warmteruiler
numeriese ondersoek
plenurnruimte, lugdinamiese gedrag
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51616 |
| Date | 12 1900 |
| Creators | Meyer, C. J. (Christiaan Johannes) |
| 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 | English |
| Type | Thesis |
| Format | 1 v. (various pagings) : ill. |
| Rights | Stellenbosch University |
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