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Effect of water maldistribution on cooling tower fill performance evaluation

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: A 1.5 x 1.5 m2 counter-flow fill performance test facility is described in detail.
Instrumentation was selected and installed in the cooling tower fill test facility and
calibrated to ensure measurement accuracy. A facility control program was written
to simplify the operation of the test facility via a user interface. The program
calculates automatically the Merkel number and loss coefficients as measures of
fill thermal and flow performance respectively. A spray frame was designed and
manufactured to ensure uniform water distribution to the fill. The water
distribution through different fills with varying fill heights and different water
flow rates was measured. The water attached to the walls of the test facility was
examined.
Film, trickle and splash fills are tested in the upgraded test facility. The film and
trickle fill performance determined during testing is deemed acceptable as these
fills have minimal migration effects. Fills with poor distribution effects and large
migration of water towards the walls of the test facility, like the splash fill tested,
cannot to be tested accurately in a 1.5 x 1.5 m2 test section as the results do not
represent the performance of the fill in a relatively large cooling tower.
Other aspects examined were:
• air flow uniformity
• air fill bypass effects
• location of water inlet and outlet temperature measurement points
• location of pressure measurement probes.
It was determined that, in the current test facility:
• air uniformity is suitable for performance testing
• air bypass effects can be ignored for open fills and can be minimised for
dense fills by packing sponge between the fill and walls
• water inlet and outlet temperatures should be measured in the pipe-work,
resulting in a measurement method that is not influenced by the relative
weightings of each thermocouple
• pressure difference over the fill height measured by the pressure
measurement tap is independent of its location on the fill outlet plane
provided the pressure measurement points are perpendicular to the air
stream and are not against the walls. / AFRIKAANSE OPSOMMING: 'n 1.5 x 1.5 m² Teenvloei pakking werkverrigting toetsfasiliteit word in detail
beskryf. Instrumentasie is gekies en geïnstalleer in die koeltoring pakking
toetsfasiliteit en gekalibreer om akkuraatheid te verseker. 'n Fasiliteit beheer
program is geskryf om die gebruik van die toetsfasiliteit te vereenvoudig. Die
program het ‘n vriendelike gebruikers intervalk. Die program bereken outomaties
die Merkel-getal en verlies koëffisiënte as mate van pakking termiese- en vloeiwerksverrigting.
'n Sproeiraam is ontwerp en vervaardig om uniforme water
verspreiding aan die pakking te verseker. Die water verspreiding deur verskillende
pakkings met verskillende pakking hoogtes en water vloei snelhede is gemeet. Die
water aangeheg aan die mure van die toetsfasiliteit is ook ondersoek.
Film, druppel en spat pakkings word in die opgegradeerde toetsfasiliteit getoets.
Die film- en druppelpakking werksverrigting bepaal tydens die toetse is
aanvaarbaar, aangesien hierdie pakkings minimale migrasie effekte het. Pakking
met swak verspreiding effekte en 'n groot migrasie van water na die wande van die
toetsfasiliteit, soos gevind met die spatpakking toetse, kan nie met akkuraatheid in
'n 1.5 x 1.5 m² toets seksie getoets word nie omdat die resultate nie die
werkverrigting van die pakking verteenwoordig in 'n relatief groot koeltoring.
Ander aspekte wat ondersoek was:
• lugvloei uniformiteit
• lug omleiding effeckte
• die posisie van water in- en uitlaat temperatuur meetpunte
• posisie van die drukmeetapparaat.
Dit is vasgestel dat, in die huidige toetsfasiliteit
• lugvloei eenvormigheid geskik is vir prestasietoetsing
• lug omleiding effekte kan geïgnoreer word vir oop pakkings en kan
verklein word vir digte pakkings deur spons tussen die pakking en mure te
pak
• water inlaat- en uitlaattemperature behoort gemeet te word in die pypwerk
en lei tot 'n metings metode wat nie beïnvloed word deur die relatiewe
gewigte van elke thermokoppel nie
• die druk verskil gemeet deur die drupmeetpunte oor die pakkinghoogte is
onafhanklik van hul posisie op die pakkinguitlaatvlak op voorwaarde dat
die drukmeetpunte loodreg is teen die lugstroom en nie teen die mure nie.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6841
Date03 1900
CreatorsBertrand, Timothy Paul
ContributorsKroger, D. G., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
PublisherStellenbosch : University of Stellenbosch
Source SetsSouth African National ETD Portal
Languageen_ZA
Detected LanguageEnglish
TypeThesis
Format1 v. (various pagings) : ill.
RightsUniversity of Stellenbosch

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