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Owen, Michael Trevor Foxwell. "Air-cooled condenser steam flow distribution and related dephlegmator design considerations." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85731.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The steam-side side operation of a practical air-cooled steam condenser is investigated using a combination of CFD, numerical, analytical and experimental methods. Particular attention is directed towards the vapor flow distribution in the primary condensers and dephlegmator performance. Analysis of the vapor flow in the distributing manifold, connecting the steam turbine exhaust to the air-cooled heat exchangers, highlights the importance of careful design of the guide vanes in the manifold bends and junctions. Improved guide vane design and configuration can reduce the steam-side pressure drop over the manifold and improve the vapor flow distribution, which may be beneficial to condenser operation. The vapor flow in the primary condensers is shown to exhibit a non-uniform distribution amongst the heat exchanger tubes. The vapor flow distribution is strongly linked to the distribution of tube inlet loss coefficients through the heat exchanger bundles. The non-uniform flow distribution places an additional demand on dephlegmator performance, over and above the demands of row effects in the case of multi-row primary condenser bundles. Row effects are shown to account for as much as 70 % of available dephlegmator capacity in this case. Simultaneously, inlet loss coefficient distributions can account for up to 30 % of dephlegmator capacity. In some situations then, the dephlegmator is fully utilized under ideal operating conditions and there is no margin of safety to cope with non-ideal operation of the primary condensers. The upstream regions of the primary condensers are therefore exposed to a high risk of undesirable noncondensable gas accumulation. Reduced dephlegmator capacity due to insufficient ejector performance may further compound this problem. Single-row primary condenser bundles eliminate row effects and thereby significantly reduce the demands on dephlegmator performance. The use of such bundles in the dephlegmator would also measurably reduce ejector loading. In light of the findings of this study, it is recommended that single-row bundles be considered as the primary option for future air-cooled condenser applications. A hybrid (dry/wet) dephlegmator concept is analysed and shown to be able to provide measurably enhanced dephlegmator performance when operating in wet mode, while consuming only a small amount of water. The enhanced dephlegmator cooling translates to an increase in total air-cooled condenser capacity of up to 30 % at high ambient temperatures in this case. The benefit of this enhanced cooling capacity to steam turbine output may be significant. The hybrid dephlegmator concept therefore offers a simple, cost-effective and sustainable solution to the issue of reduced air-cooled condenser performance during hot periods. Careful design of the first and second stage bundle configurations in the hybrid dephlegmator is necessary to avoid flooding in the first stage during wet operation of the second. Furthermore, the slightly poorer dry-operation performance of the hybrid dephlegmator results in increased risk of non-condensable gas accumulation in multi-row primary condensers. Again, single-row primary condenser bundles would lay rest to such concerns.
AFRIKAANSE OPSOMMING: Die bedryf aan die stoom-kant van ʼn praktiese lugverkoelde-stoomkondensor word ondersoek met behulp van 'n kombinasie van berekeningsvloeimeganika, numeriese, analitiese en eksperimentele metodes. ʼn Spesifieke fokus word geplaas op die dampvloeiverspreiding in die primêre kondensors asook die deflegmatorwerksverrigting. Ontleding van die damp vloei in die verdeelspruitstuk, wat die uitlaat van die stoomturbine aan die lugverkoelde-stoomkondensor koppel, beklemtoon die belangrikheid van noukeurige ontwerp van die leilemme in die spruitstukdraaie en aansluitings. Verbeterde leilemontwerp en opstelling kan die drukval aan die stoom-kant van die draaie en aansluitings verminder en die dampvloeiverspreiding verbeter. Dit kan gevolglik lei tot verbeterde werksverrigting van die kondensor. Die studie toon dat ʼn nie-eenvormige dampvloeiverspreiding in die warmteruilerbuise van die primêre kondensors bestaan. Die verspreiding van buisinlaat-verlieskoëffisiënte deur die bundels van die warmteruiler is sterk afhanklik van die voorgenome dampvloeiverspreiding. Die nie-eenvormige vloeiverspreiding veroorsaak 'n groter aanvraag na deflegmator-werksverrigting, bo-en-behalwe nog vereistes van ry-effekte in die geval waar multi-ry-bundels vir primêre kondensors gebruik word. Ry-effekte is verantwoordelik vir so veel as 70 % van die beskikbare deflegmator kapasiteit. Terselfdertyd kan die verspreiding van inlaat-verlieskoëffisiënte verantwoordelik wees vir tot 30 % van die deflegmator kapasiteit. In sommige gevalle is die deflegmator dus ten volle aangewend onder ideale bedryfstoestande, en bestaan daar geen band van veiligheid om nie-ideale werksverrigting van die primêre kondensor te hanteer nie. Sekere dele van die stroom-op primêre kondensors word dus blootgestel aan 'n hoë risiko vir die opbou van ongewenste nie-kondenseerbare gasse. Verder kan ‘n vermindering in deflegmator kapasiteit, weens onvoldoende werksverrigting van die vakuumpompe, dié probleem vererger. Enkel-ry-bundels vir primêre kondensors vermy ry-effekte en lei sodoende tot ʼn aansienlike vermindering in die aanvraag na deflegmator-werksverrigting. Die gebruik van sulke bundels in die deflegmator sou die vakuumpomplas ook meetbaar verminder. Uit die bevindinge van hierdie studie word dit aanbeveel dat enkel-ry bundels beskou word as die primêre opsie vir toekomstige lugverkoelde-kondensor aansoeke. ’n Konsep vir ’n hibriede-deflegmator (droog/nat) word ontleed. Die studie toon dat, deur hierdie konsep in die nat-modus te gebruik, ’n meetbare verbetering in deflegmator-werksverrigting gesien kan word, ten koste van net ʼn klein hoeveelheid waterverbruik. Die verbetering in verkoelingsvermoë van die deflegmator beteken ʼn toename van tot 30 % in die totale verkoelingsvermoë van die lugverkoelde-kondensor gedurende periodes wanneer hoë omgewingstemperature heersend is. Die voordeel van hierdie verbeterde verkoelingsvermoë op die werksuitset van die stoomturbine kan beduidend wees. Die konsep vir ’n hibriede-deflegmator bied dus 'n eenvoudige, koste-effektiewe en volhoubare oplossing vir warm atmosferiese periodes, wanneer die lugverkoelde-kondensor se verkoelingsvermoë afneem. Noukeurige ontwerp van die eerste en tweede fase bundelkonfigurasies in die hibriede-deflegmator is nodig om oorstroming in die eerste fase, tydens nat werking van die tweede fase, te verhoed. Verder veroorsaak die effens swakker werksverrigting, gedurende die bedryf van die hibriede-deflegmator in die droog-modus, ʼn verhoogde risiko vir die opbou van nie-kondenseerbare gasse in multi-ry primêre kondensors. Weereens sal enkel-ry-bundels in primêre kondensors hierdie probleem oplos.
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Subramaniam, Vishwanath. "Design of Air-cooled Microchannel Condensers for Mal-distributed Air Flow Conditions." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5088.
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Air-cooled condensers are routinely designed for a variety of applications, including residential air-conditioning systems. Recent attempts at improving the performance of these heat exchangers have included the consideration of microchannel tube, multilouver fin heat exchangers instead of the more conventional round tube-plate fin designs. In most packaged air-conditioning systems, however, the condenser surrounds the compressor and other auxiliary parts in an outdoor unit, with an induced draft fan at the top of this enclosure. Such a configuration results in significant mal-distribution of the air flow arriving at the condenser, and leads to a decrease in performance. This work addresses the issue of mal-distribution by adapting the air-side geometry to the expected air flow distribution. A microchannel tube, multilouver fin condenser is first designed to transfer the desired heat rejection load for an air-conditioning system under uniform air flow conditions. Tube-side pass arrangements, tube dimensions, and fin and louver geometry are varied to arrive at a minimum mass, 2.54 kg condenser that delivers the desired heat load of 14.5 kW. The design model is then used to predict the performance of the condenser for a variety of air flow distributions across the heat exchanger. It is found that for a 50% air flow mal-distribution, the required condenser mass increases to 2.73 kg. The air-side geometry (fin density and height) of the condenser is then systematically changed to optimally distribute the air-side surface area across the condenser to best address the mal-distributed air flow. It is found that linear fin density and height variations from the mean value of 40% and 20%, respectively, keeping the mean fin density and height the same, reduce the required condenser mass to 2.65 kg even for this mal-distributed air-flow case. The influence of geometry variations on heat transfer coefficients, fan power and other performance measures is discussed in detail to guide the judicious choice of surface area and tube-side flow area allocations for any potential air flow mal-distribution. The results from this study can be used for the design of air-cooled condensers under realistic flow conditions.
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Stewart, Susan White. "Enhanced Finned-Tube Condenser Design and Optimization." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5289.
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Enhanced Finned-Tube Condenser Design and Optimization
Susan W. Stewart
173 pages
Directed by Dr. Sam V. Shelton
Finned-tube heat exchangers are widely used in space conditioning systems, as well as any other application requiring heat exchange between liquids and gases. Their most widespread use is in residential air conditioning systems. Residential systems dictate peak demand on the U.S. national grid, which occurs on the hot summer afternoons, and thereby sets the expensive infrastructure requirement of the nations power plant and electrical distribution system. In addition to peak demand, residential air conditioners are major energy users that dominate residential electrical costs and environmental impact.
The only significant opportunity for electrical power use reduction of residential air conditioners is in technology improvement of the finned-tube heat exchangers, i.e., condenser and evaporator coils. With the oncoming redesign of these systems in the next five years to comply with the regulatory elimination of R-22 used in residential air conditioners today, improvement in the design technology of these systems is timely.
An air conditioner condenser finned-tube coil design optimization methodology is derived and shown to lead to improved residential air conditioner efficiency at fixed equipment cost. This nonlinear optimization of the 14 required design parameters is impractical by systematic experimental testing and iteration of tens of thousands condenser coils in an air conditioning system. The developed methodology and results can be used in the redesign of residential systems for the new mandated environmentally friendly refrigerants and to meet increasing regulatory minimum system efficiencies.
Additionally, plain fins and augmented fins, (louvered), are compared using the developed model and optimization scheme to show the effect of the augmentation on system performance. Furthermore, an isolated condenser model was developed using condenser entropy generation minimization as the figure of merit to minimize the model complexity and computation time. Isolated model optimizations are compared with the system model optimum designs.
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Kloda, Michal. "Vzduchem chlazený kondenzátor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231824.
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The Master’s thesis dealing with air-cooled condensers is split into four sections. The first section shows an overview of air cooling, introduction into air-cooled condensers of A-frame shape and finned tubes. The second section deals with heat transfer on the steam side and deals with trapped incondensables on the steam side of ACC. The third section deals with heat transfer on the air side, shows a brief overview of fans and selected problems on the air side. In the last section the simplified thedmodynamic calculation of air-cooled condenser is shown.
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Aspelund, Kristinn A. "Optimization of plate-fin-and-tube condenser performance and design for refrigerant R-410A air-conditioner." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19488.
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Sadler, Emma May. "Design analysis of a finned-tube condenser for a residential air-conditioner using R-22." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17951.
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Wright, Monifa Fela. "Plate-Fin-And-Tube condenser perfomance and design for a refrigerant R-410A air-conditioner." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17296.
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Squicciarini, Martin. "The air cooled condenser optimization." Kansas State University, 2016. http://hdl.handle.net/2097/34546.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Donald L. Fenton
Today air cooled chillers are often used in industrial applications where chilled water is pumped through processes or laboratory equipment. Industrial chillers are used for the controlled cooling of products, mechanisms and factory machinery in a wide range of industries. However, there is limited information on condenser coil design for a simulated model that uses R407c in a process chiller system with a focus on the finned tube condenser design. Therefore, a simulation tool that evaluates the performance of a condenser design, e.g. frontal area, cost, and overall system efficiency would be very useful. An optimization calculator for the air cooled fin-tube condenser design was developed. This calculator allows a user to specifically select the condenser geometric design parameters including the overall condenser length and height, number of rows, number of circuits, row and tube spacing, fin thickness, fin density, tube inner and outer diameters, and the quantity and power of the fan motors. This study applied the calculator finding an optimum condenser design for various frontal areas and cost constraints. The calculator developed is appropriate for engineering designers for use in the process chiller industry.
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Van, Rooyen J. A. "Performance trends of an air-cooled steam condenser under windy conditions." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1629.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007.Air-cooled steam condensers (ACSC’s) are increasingly employed to reject heat in modern power plants. Unfortunately these cooling systems become less effective under windy conditions and when ambient temperatures are high. A better understanding of the fundamental airflow patterns about and through such air-cooled condensers is essential if their performance is to be improved under these conditions. For known flow patterns, improved fan designs are possible and flow distortions can be reduced by means of extended surfaces or skirts, windwalls and screens. Spray cooling of the inlet air or the addition of an evaporative cooling system can also be considered for improving performance under extreme conditions. The present numerical study models the air flow field about and through an air-cooled steam condenser under windy conditions. The performance of the fans is modeled with the aid of a novel numerical approach known as the “actuator disc model”. Distorted airflow patterns that significantly reduce fan performance in certain areas and recirculatory flows that entrain hot plume air are found to be the reasons for poor ACSC performance. It is found that the reduction in fan performance is the main reason for the poor ACSC performance while recirculation of hot plume air only reduces performance by a small amount. Significant improvements in ACSC performance are possible under these conditions if a cost effective skirt is added to the periphery of the ACSC while the installation of a screen under the ACSC has very little effect.
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Honing, Werner. "Steam flow distribution in air-cooled condenser for power plant application." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2540.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: Air-cooled steam condensers are used in arid regions where adequate cooling water is not available or very expensive. In this thesis the effect of steam-side and air-side effects on the condenser performance, steam distribution and critical dephlegmator length is investigated for air-cooled steam condensers as found in power plants. Solutions are found so that no backflow is present in the condenser. Both single and two-row condensers are investigated. The tube inlet loss coefficients have the largest impact on the critical dephlegmator tube length in both the single and two-row condensers. The critical dephlegmator tube lengths were determined for different dividing header inlet geometries and it was found that a step at the inlet to the dividing header resulted in the shortest tubes. Different ambient conditions were found to affect the inlet steam temperature, the steam flow distribution, heat rejection distribution and the critical dephlegmator length for the single and two-row condensers. There were differences in the steam mass flow distributions for the single and two-row condensers with opposite trends being present in parts of the condenser. The single-row condenser’s critical dephlegmator tube lengths were shorter than those of the two-row condenser for the same ambient conditions. Areas of potential backflow change with different ambient conditions and also differ between a single and two-row condenser. The two-row condenser always have an area of potential backflow for the first row at the first condenser fan unit.
AFRIKAANSE OPSOMMING: Droë lug-verkoelde stoom kondensors word gebruik in droë gebiede waar genoegsame verkoelingswater nie beskikbaar is nie of baie duur is. In hierdie tesis word die effek van stoomkant en lugkant effekte op die vermoë van die kondensor, die stoomvloeiverdeling en kritiese deflegmator lengte ondersoek vir lug-verkoelde stoom kondensors soos gevind in kragstasies. Dit word opgelos sodat daar geen terugvloei in enige van die buise is nie. ʼn Enkel- en dubbelry kondensor word ondersoek. Die inlaatverlieskoëffisiënte van die buise het die grootste impak op die lengte van die kritiese deflegmator buise in beide die enkel- en dubbelry kondensors. Die kritiese deflegmator buis lengtes is bereken vir verskillende verdeelingspyp inlaat geometrië en dit is gevind dat ʼn trap by die inlaat van die verdeelingspyp die kortste buise lewer. Dit is gesien dat verskillende omgewingskondisies die inlaat stoom temperatuur, die stoomvloeiverdeling, die warmteoordrag verdeling en die kritiese lengte van die deflegmator buise vir die enkel- en dubbelry kondensor. Daar was verskille tussen die stoomvloeiverdelings vir die enkel- en dubbelry met teenoorgestelde neigings in dele van die kondensor. Die kritiese deflegmator buis lengte vir die enkelry kondensor was korter as die vir die dubbelry kondensor vir dieselfde omgewingskondisies. Die areas in die kondensor waar terugvloei moontlik kan plaasvind in die kondensor verander met ongewingskondisies en verskil vir die enkel- en dubbelry kondensers. Die dubbelry kondensor het altyd ʼn area van moontlike terugvloei vir die eerste buisry by die eerste kondensor waaiereenheid.
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Joubert, Retief. "Influence of geometric and environmental parameters on air-cooled steam condenser performance." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4153.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Air-cooled steam condensers (ACSCs) are used in the power generation industry to directly condense turbine exhaust steam in areas where cooling water is expensive or unavailable. Large axial flow fans force ambient air through A-frame heat exchanger bundles made up of a number of rows of finned tubes through which the steam is ducted and consequently condensed during the heat transfer process to the air. The heat rejection rate or performance of an ACSC is proportional to the air mass flow rate, determined by fan volumetric performance, and the temperature difference between the finned tubes and the air. The air flow through a 30 fan ACSC (termed the generic ACSC) operating under windy conditions is solved using the commercial computational fluid dynamics (CFD) code FLUENT and the required data is extracted from the solution to calculate performance trends. It is found that fan performance is reduced due to a combination of factors. The first is additional upstream flow losses caused by separated flow occurring primarily at the leading edge of the ACSC and secondarily at the fan bellmouth inlets. The second factor leading to reduced fan performance is the presence of distorted flow conditions at the fan inlets. Hot plume air recirculation is responsible for decreased ACSC thermal performance due to increased fan inlet air temperatures. It is found that reduced fan performance is the greater contributor to reduced ACSC performance. The performance effects of varying two geometrical parameters of the generic ACSC, namely the fan platform height and the windwall height, are investigated under windy conditions. It is found that each parameter is linked to a specific mechanism of performance reduction with the fan platform height affecting fan performance and the windwall height affecting recirculation. The respective platform and windwall heights specified for the generic ACSC are found to provide acceptable performance results. To mitigate wind induced performance reductions a number of modification and additions to the ACSC are investigated. These primarily aim at improving fan performance and included the addition of walkways or skirts, the addition of wind screens beneath the fan platform, removing the bellmouth fan inlets, using different types of fans and increasing fan power. The addition of a periphery walkway and windscreens is considered to be the most practical methods of improving ACSC performance under windy conditions. The generic ACSC is modified to include both modifications and under high wind conditions the performance is found to increase measurably. The modifications also resulted in the ACSC performance being less sensitive to wind direction effects.
AFRIKAANSE OPSOMMING: Lugverkoelde kondensators word in die kragopwekkings industrie gebruik om turbine uitlaatstoom te kondenseer, veral in gebiede waar verkoelingwater duur of onbeskikbaar is. Aksiaalvloei-waaiers forseer omgewingslug deur A-raam warmteuitruiler bondels wat bestaan uit verskeie rye vinbuise. Die uitlaatstoom vloei in die vinbuise en kondenseer as gevolg van die warmteoordrag na die lug. Die warmteoordragkapasiteit van die lugverkoelde stoom kondensator is eweredig aan die massavloei-tempo van die lug, wat bepaal word deur die waaierwerkverigting, en die temperatuur verskil tussen die vinbuise en die lug. Die lugvloei deur 'n 30 waaier lugverkoelde stoom kondensator (genoem die generiese lugverkoelde stoom kondensator) onderworpe aan winderige toestande word opgelos deur die gebruik van die kommersiële vloeidinamika-pakket, FLUENT. Die nodige data is onttrek uit die oplossing en werkverrigting neigings is bereken. Dit is gevind dat waaierwerkverigting verminder as gevolg van 'n kombinasie van faktore. Die eerste is bykomende vloeiverliese wat veroorsaak word deur vloeiwegbreking wat plaasvind primêr by die voorste rand van die lugverkoelde stoom kondensator asook by die klokvormige waaier-inlate. 'n Tweede faktor wat lei tot vermindere waaierwerkverigting is die teenwoordigheid van lugvloeiversteurings by die waaier-inlate. Hersirkulering van warm pluim lug is ook verantwoordelik vir verminderde lugverkoelde stoom kondensator werkverrigting. Daar word bevind dat die vermindering in waaierwerkverrigting die grootste bydraende faktor tot vermindere lugverkoelde stoom kondensator werkverrigting is. Die effek van verandering van twee geometriese lugverkoelde stoom kondensator parameters, naamlik die waaierplatformhoogte en die windwandhoogte is ondersoek onder winderige toestande. Daar word bevind dat elk van die parameters gekoppel is aan 'n spesifieke meganisme van vermindere lugverkoelde stoom kondensator verrigting: Die waaierplatformhoogte beïnvloed waaierverrigting terwyl die windwandhoogte hersirkulering beinvloed. Daar word ook bevind dat die onderskeie waaierplatform- and windwandhoogtes van die generiese lugverkoelde stoom kondensator, van so 'n aard is dat dit aanvaarbare werkverrigting tot gevolg het. Om verlaging in werksverrigting in winderige toestande te verminder is verskeie modifikasies en byvoegings tot die lugverkoelde stoom kondensator ondersoek wat primêr gemik is op verbetering in waaierwerkverigting. Die ondersoek dek die byvoeging van 'n loopvlak, die byvoeging van windskerms onder die waaierplatform, verwydering van die klokvormige waaier-inlate, die gebruik van verskillende waaiers en die verhoging van waaierdrywing. Daar was besluit dat die byvoeging van 'n loopvlak rondom die rand van die lugverkoelde stoom kondensator en die byvoeging van windskerms die mees praktiese manier was om die lugverkoelde stoom kondensator verigting te verbeter. Die generiese lugverkoelde stoom kondensator was aangepas om beide veranderings in te sluit en meetbare verbetering in werkrigting was verkry. Die veranderings het ook meegebring dat die lugverkoelde stoom kondensator minder sensitief is vir windrigting effekte.
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Louw, Francois G. "Performance trends of a large air-cooled steam condenser during windy conditions." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6593.
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Owen, Michael Trevor Foxwell. "A numerical investigation of air-cooled steam condenser performance under windy conditions." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4101.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This study is aimed at the development of an efficient and reliable method of evaluating the performance of an air-cooled steam condenser (ACSC) under windy conditions, using computational fluid dynamics (CFD). A two-step modelling approach is employed as a result of computational limitations. The numerical ACSC model developed in this study makes use of the pressure jump fan model, amongst other approximations, in an attempt to minimize the computational expense of the performance evaluation. The accuracy of the numerical model is verified through a comparison of the numerical results to test data collected during full scale tests carried out on an operational ACSC. Good correlation is achieved between the numerical results and test data. Further verification is carried out through a comparison to previous numerical work. Satisfactory convergence is achieved for the most part and the few discrepancies in the results are explained. The effect of wind on ACSC performance at El Dorado Power Plant (Nevada, USA) is investigated and it is found that reduced fan performance due to distorted flow at the inlet of the upstream fans is the primary contributor to the reduction in performance associated with increased wind speed in this case. An attempt is subsequently made to identify effective wind effect mitigation measures. To this end the effects of wind screens, solid walkways and increasing the fan power are investigated. It is found that the installation of an appropriate wind screen configuration provides a useful means of reducing the negative effects of wind on ACSC performance and an improved wind screen configuration is suggested for El Dorado. Solid walkways are also shown to be beneficial to ACSC performance under windy conditions. It is further found that ACSC performance increases with walkway width but that the installation of excessively wide walkways is not justifiable. Finally, increasing the fan power during periods of unfavourable ambient conditions is shown to have limited benefit in this case. The model developed in this study has the potential to allow for the evaluation of large ACSC installations and provides a reliable platform from which further investigations into improving ACSC performance under windy conditions can be carried out.
AFRIKAANSE OPSOMMING: Hierdie studie is daarop gemik om die ontwikkeling van 'n geskikte en betroubare metode van evaluering van die verrigting van ’n lugverkoelde stoom-kondensator (air-cooled steam condenser, ACSC) onder winderige toestande, met behulp van numeriese vloei-dinamika. ’n Twee-stap modelleringsbenadering is aangewend as gevolg van rekenaar beperkings. Die numeriese ACSC-model wat in hierdie studie ontwikkel is, maak gebruik van die druksprong waaier model, asook ander benaderings, in ’n poging om die berekeningskoste van die verrigting-evaluering te verminder. Die akkuraatheid van die numeriese model is bevestig deur middel van ’n vergelyking van die numeriese resultate met toetsdata ingesamel tydens die volskaal toetse uitgevoer op ’n operasionele ACSC. Goeie korrelasie is bereik tussen die numeriese resultate en toetsdata. Verdere bevestiging is uitgevoer deur middel van ’n vergelyking met vorige numeriese werk. Bevredigende konvergensie is in die algemeen bereik en die paar verskille in die resultate word verduidelik. Die effek van wind op ACSC verrigting by El Dorado Power Plant (Nevada, VSA) is ondersoek, en daar is bevind dat verlaagde waaierverrigting, as gevolg van vervormde vloei by die inlaat van die stroomop waaiers, die primêre bydraer is tot die afname in ACSC werkverrigting geassosieer met verhoogde windsnelheid in hierdie geval. ’n Poging word dan aangewend om effektiewe wind-effek velagingsmaatreëls te identifiseer. Windskerms, soliede wandelvlakke en die verhoging van die waaierkrag word gevolglik ondersoek. Daar is bevind dat die installasie van ’n toepaslike windskerm-opset ’n nuttige middel tot ’n vermindering van die negatiewe effekte van wind op ACSC verrigting bied, en ’n verbeterde windskerm opset is voorgestel vir El Dorado. Soliede wandelvlakke word ook aanbeveel as voordelig vir ACSC verrigting onder winderige toestande. Dit is verder bevind dat die ACSC prestasie verhoog met wandelvlak breedte, maar dat die installasie van ’n te ruim wandelvlak nie regverdigbaar is nie. Ten slotte, word bewys dat die verhoging van die waaierkrag tydens periodes van ongunstige omgewingsomstandighede ’n beperkte voordeel in hierdie geval het. Die model wat ontwikkel is in hierdie studie het die potensiaal om voorsiening te maak vir die evaluering van groot ACSC- installasies en bied ’n betroubare platform vanwaar verdere ondersoeke tot die verbetering van ACSC verrigting onder winderige toestande uitgevoer kan word.
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Hyden, Kathryn R. "Controlling Condensate Outlet Temperature on an Air Cooled Condenser in MATLAB/Simulink." Youngstown State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1403036613.
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Juráš, Filip. "Kondenzátor páry." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319685.
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The Master´s thesis is dealing with water-cooled condensers and is splitted into three main parts. The first section provides general knowledge about condensers and heat exchangers, including the basic information of hydrophobic surfaces. These surfaces were used during verifying the impact of hydrophobicity on the heat exchange in water steam. The second section describes an experimental testing. It shows the difference between hydrophobic and nonhydrophobic surfaces and their impact on the heat exchange. The third and the last part of this thesis is design and calculation of water-cooled condenser. The design of the condenser is supported by drawings placed in attachement.
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Bredell, J. R. (Johann Richard). "Numerical investigation of fan performance in a forced draft air-cooled steam condenser." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/21201.
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Thesis (MScIng)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Forced draft air-cooled steam condensers (ACSCs) consisting of multiple fan units are used in direct cooled power plants to condense steam in a closed steam cycle. Axial flow fans located below an A-frame configuration of finned tube heat exchanger bundles, force ambient air through the system. In so doing, heat from the condensing steam is rejected to the environment via the finned tubes. The performance of an air-cooled system is proportional to the air mass flow rate and the temperature difference between the finned tubes and the ambient air. A variation in either will directly affect the efficiency of the steam turbines. Air flow distortions at the fan inlet caused by structures, wind and other fans may result in a significant reduction in flow rate as well as fan blade vibration. This phenomenon has an adverse affect on the cooling capacity of an ACSC, and consequently turbine performance, due to a decrease in air mass flow rate. In this study the effect of inlet flow distortions on fan performance (i.e. flow rate and fan shaft power) in an ACSC is numerically investigated by modelling a section (or sector) of such a system using the commercial computational fluid dynamics (CFD) code, FLUENT. Fan performance at different platform heights, and corresponding different degrees of inlet flow distortions, is investigated. The performance of two types of axial flow fans are also compared. The two fans have the same diameter, number of blades and rotational speed, but feature different blade designs, and hub-tip-ratios of respectively 0.153 and 0.4. A fan model based on blade element theory, better known as an actuator disc model, is used to numerically model the fans. Previous experimental studies have shown that a solid walkway installed along the edge or periphery of an ACSC platform can significantly increase the flow rate through the fans situated along the platform edge. The effects of such a walkway, and other windscreens on fan performance, are numerically investigated. Numerical predictions correlate with earlier experimental results: the flow rate and fan shaft power are decreased by inlet flow distortions. It was found that the fan with a hub-tip-ratio of 0.4 was less affected by these flow distortions. The addition of a walkway increased the flow rate through the edge fan by up to 48 %. It is furthermore shown that wind effects can only be accurately modelled if the entire ACSC is considered.
AFRIKAANSE OPSOMMING: Geforseerde-trek lugverkoelde kondensators wat bestaan uit ʼn aantal waaier-eenhede, word in direk-verkoelde kragstasies gebruik om stoom in ʼn geslote stoomkringloop te kondenseer. Aksiaalvloei-waaiers wat onder ʼn A-raam-konfigurasie van vinbuisbundels geïnstalleer is, forseer omgewingslug deur die stelsel. Sodoende word die hitte van die kondenserende stoom aan die omgewing oorgedra deur middel van die vinbuise. Die warmteoordragkapasiteit van ʼn lugverkoelde kondensator is eweredig aan die massavloei-tempo van die lug, asook die temperatuurverskil tussen die vinbuise en die lug. ʼn Verandering in enige van dié faktore sal die benuttingsgraad van die stoomturbines direk beïnvloed. Lugvloeiversteurings by die waaier-inlate wat veroorsaak word deur geboue, wind en ander waaiers kan lei tot aansienlike verlagings in vloeitempo deur die waaiers. Sekondêre effekte soos waaierlemvibrasie kan ook veroorsaak word. In hierdie studie word die effek van inlaatvloeiversteurings op waaierwerkverrigting (dws vloeitempo en waaierdrywing) ondersoek deur ʼn seksie (of sektor) van ʼn lugverkoelde kondensator te modelleer deur gebruik te maak van die kommersiële numeriese vloeidinamika-pakket, FLUENT. Waaierwerkverrigting word by verkillende platformhoogtes, en gevolglik verskillende grade van inlaatvloeiversteurings, ondersoek. Twee verskillende waaiers word ook vergelyk. Die waaiers het dieselfde diameter, aantal lemme en rotasiespoed, maar het verkillende lem ontwerpe, en naaf-lempunt-verhoudings van onderskeidelik 0.153 en 0.4. ʼn Waaiermodel wat gebaseer is op lem-element-teorie, beter bekend as ʼn aksie-skyf-model, word gebruik om die waaiers numeries te modelleer. Vorige eksperimentele studies het bewys dat ʼn loopvlak om die rand van lugverkoelde kondensators die vloeitempo deur waaiers aansienlik kan verhoog. Die effek van so ʼn loopvlak, en ander windskerms word numeries ondersoek. Numeriese voorspellings stem ooreen met eksperimentele resultate: die vloeitempo en waaierdrywing word verlaag deur inlaat-vloeiversteurings. Dit is bevind dat die waaier met ʼn naaf-lempunt-verhouding van 0.4, minder beïnvloed word deur vloeiversteurings. ʼn Loopvlak het die vloeitempo deur die randwaaier met tot 48 % verhoog. Dit is ook bewys dat windeffekte alleenlik gemodelleer kan word deur die hele lugverkoelde kondensator in ag te neem.
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Angula, Ester. "Numerical performance evaluation of a delugeable flat bare tube air-cooled steam condenser bundle." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97151.
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Thesis (MEng)--Stellenbosch University, 2015.ENGLISH ABSTRACT: In this study, one and two-dimensional models are developed for the evaluation of the thermal performance of a delugeable flat tube bundle to be incorporated in the second stage of an induced draft hybrid (dry/wet) dephlegmator (HDWD) of a direct air-cooled steam condenser (ACSC). Both models are presented by a set of differential equations. The one-dimensional model is analysed analytically by using three methods of analysis which are: Poppe, Merkel, and heat and mass transfer analogy. The two-dimensional model is analysed numerically by means of heat and mass transfer analogy method of analysis whereby, the governing differential equations are discretised into algebraic equations using linear upwind differencing scheme. The two-dimensional model’s accuracy is verified through a comparison of the two dimensional solutions to one dimensional solutions. Satisfactory correlation between the one and two-dimensional results is reached. However, there is a slight discrepancy in the solutions, which is mainly due to the assumptions made in one-dimensional model. The effect of tube height, tube pitch, tube width, deluge water mass flow rate, frontal air velocity, steam, and air operating conditions on the heat transfer rate and air-side pressure drop for both wet and dry operating modes are investigated. The long tube height, large tube width, small tube pitch, and high frontal air velocity are found to increase the tube bundle’s performance. However, this performance is associated with a high airside pressure drop. The performance of the deluged flat tube bundle is found to be less sensitive to the changes in the deluge water mass flow rate and air operating conditions. Furthermore, the best configuration of a delugeable flat tube bundle is identified through a comparison to round tube bundle presented by Anderson (2014). The performance of the round tube bundle is found to be around 2 times, and 1.5 times of that of flat tube bundle, when both bundles operate as an evaporative and dry air-cooled condenser respectively.
AFRIKAANSE OPSOMMING: In hierdie studie is een en twee-dimensionele modelle ontwikkel vir die evaluering van die termiese prestasie van 'n benatbare plat buis bundel in die tweede stadium van 'n geïnduseerde ontwerp hibriede (droë / nat ) deflegmator van 'n direkte lugverkoelde stoom kondensator. Beide modelle is aangebied deur 'n stel van differensiaalvergelykings. Die een-dimensionele model is analities ontleed deur die gebruik van drie metodes van analise wat: Poppe, Merkel, en die hitte en massa-oordrag analogie. Die twee-dimensionele model is numeries ontleed deur middel van hitte en massa-oordrag analogie metode van analise waardeur , die regerende differensiaalvergelykings gediskretiseer in algebraïese vergelykings met behulp van lineêre windop differensievorming skema. Die tweedimensionele model se akkuraatheid is geverifieer deur 'n vergelyking van die twee dimensionele oplossings te een dimensionele oplossings. Bevredigende korrelasie tussen die een en twee-dimensionele resultate bereik word. Maar daar is 'n effense verskil in die oplossings, wat is hoofsaaklik te wyte aan die aannames wat gemaak in een-dimensional model. Die effek van buis hoogte, buis toonhoogte, buis breedte, vloed water massa-vloeitempo, frontale lug snelheid, stoom, en in die lug werktoestande op die hitte oordrag snelheid en lug - kant drukval vir beide nat en droë maatskappy modi word ondersoek. Die lang buis hoogte, groot buis breedte, klein buisie toonhoogte, en 'n hoë frontale lug snelheid gevind die buis bundel se prestasie te verhoog. Tog is hierdie prestasie wat verband hou met 'n hoë lug - kant drukval. Die prestasie van die oorstroom plat buis bundel gevind word minder sensitief vir die veranderinge in die vloed water massa-vloeitempo en lug werktoestande. Verder is die beste opset van 'n benatbare plat buis bundel geïdentifiseer deur 'n vergelyking met ronde buis bundel aangebied deur Anderson (2014). Die prestasie van die ronde buis bundel gevind word om 2 keer, en 1.5 keer van daardie plat buis bundel , wanneer beide bundels funksioneer as 'n damp en droë lugverkoelde kondensor onderskeidelik.
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Heyns, Johan Adam. "Performance characteristics of an air-cooled steam condenser incorporating a hybrid (dry/wet) dephlegmator." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/350.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008.This study evaluates the performance characteristics of a power plant incorporating a steam turbine and a direct air-cooled dry/wet condenser operating at different ambient temperatures. The proposed cooling system uses existing A-frame air-cooled condenser (ACC) technology and through the introduction of a hybrid (dry/wet) dephiegmator achieves measurable enhancement in cooling performance when temperatures are high. In order to determine the thermal-flow performance characteristics of the wet section of the dephlegmator, tests are conducted on an evaporative cooler. From the experimental results, correlations for the water film heat transfer coefficient, air-water mass transfer coefficient and the air-side pressure drop over a deluged tube bundle are developed. During periods of high ambient temperatures the hybrid (dry/wet) condenser operating in a wet mode can achieve the same increased turbine performance as an oversized air-cooled condenser or an air-cooled condenser rith adiabatic cooling (spray cooling) of the inlet air at a considerably lower cost. For the same turbine power output the water consumed by an air-cooled condenser incorporating a hybrid (dry/wet) dephlegmator is at least 20% less than an air- cooled condenser with adiabatic cooling of the inlet air.
Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University
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Al-Bakri, Basim Abdulrazzak. "Micro-channel air cooled condenser performance with two-phase flow of zeotropic refrigerant at high ambient temperatures." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/20646/.
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A study of the thermal performance of an air-cooled micro-channel condenser using zeotropic refrigerant blend R-410A operating at high reduced pressure and at hot climate was conducted. The investigation of the condensation process at high ambient temperature is worth considering because the condensation saturation temperature should be high enough to be cooled by air at high ambient temperature. In this case a high operating pressure corresponding to the high condensation temperature is required; therefore, the condensation process of R-410A occurs at near-critical pressure and the vapour compression cycle operates in hot weather. In order to achieve a successful condensation process operating at hot climate, micro-channel tubes were suitable because of the high heat transfer coefficient associated with tubes of very small hydraulic diameter. The local heat transfer coefficient of R-410A was determined experimentally during the condensation process across the vapour-liquid dome at 0.7 and 0.8 reduced pressures and at 35 and 45°C ambient air temperatures, in two different rectangular tubes of Dₕ* =1.26 and 0.52 mm, over a mass flux range of 200≤G*≤800 kg/ m2s. Although, the temperature glide of the refrigerant R-410A was sufficiently small, the measurement of the mass flux and the heat transfer during condensation with other measuring parameters were always difficult to achieve with a high level of accuracy. The latest technology of the micro-foil heat flux sensor technique was used with a bespoke facility to accurately determine the heat duty of condensation along the micro-channel tubes. The behaviour of the heat transfer coefficient with the vapour quality was addressed. In addition, the behaviour of heat flux, vapour quality and wall temperature with the thermal length of the channel were intensively studied. The heat transfer coefficient was found to increase with the mass flux and the vapour quality and to decrease with the ambient temperature. Correlations by other researchers mostly disagreed with the present experimental data. Annular flow regime was adopted due to the cross section of tubes at these diameters. A new correlation in annular flow regime that accounted for the effect of near critical pressure of such refrigerant and the high temperature of the coolant air in the geometry of tubes under consideration was proposed to predict the heat transfer coefficient of condensation for which the available models are insubstantial. The resulting correlation successfully computed the experimental data. The physical comprehension and correlation resulting from this research contribute to enhance the existing knowledge for designing and optimising new equipment that utilise R-410A for air-conditioning and refrigeration applications, particularly in hot climates.
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Toman, Filip. "Výpočet tepelné bilance využití latentního tepla spalin pomocí kondenzátoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378488.
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Thesis is focused on calculation of the condenser of flue gas, which is created by burning of natural gas. In the first part is theoretical overview of equations describing film condensation and physical properties of the flue gas. The second part deals with practical thermal calculation of the specified condenser. In third part parametric study is done in which a tempature of cooling water at inlet and the coefficient of excess air are changed. The last part of the thesis is dedicated to geometric design of the flue gas condenser whose required power is 8 MW.
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Fourie, Neil. "Simulating the effect of wind on the performance of axial flow fans in air-cooled steam condenser systems." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95977.
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Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: The use of air-cooled steam condensers (ACSCs) is the preferred cooling method in the chemical and power industry due to stringent environmental and water use regulations. The performance of ACSCs is however highly dependent on the influence of windy conditions. Research has shown that the presence of wind reduces the performance of ACSCs. It has been found that cross-winds (wind perpendicular to the longest side of the ACSC) cause distorted inlet flow conditions, particularly at the upstream peripheral fans near the symmetry plane of the ACSC. These fans are subjected to what is referred to as '2-D' wind conditions, which are characterised by flow separation on the upstream edge of the fan inlets. Experimental investigations into inlet flow distortion have simulated these conditions by varying the fan platform height. Low platform heights resulted in higher levels of inlet flow distortion, as also found to exist with high cross-wind speeds. This investigation determines the performance of various fan configurations (representative of configurations used in the South- African power industry) subjected to distorted inlet flow conditions through experimental and numerical investigations. The similarity between platform height and cross-wind effects is also investigated and a correlation between system volumetric effectiveness, platform height and cross-wind velocity is found.
AFRIKAANSE OPSOMMING: Die gebruik van lugverkoelde stoom kondensors (LVSK's) word verkies as 'n verkoelingsmetode in die chemiese- en kragvoorsieningsindustrie as gevolg van streng omgewings- en waterverbruiksregulasies. Die werkverrigting van LVSK's word egter grootliks beïnvloed deur die teenwoordigheid van wind. Navorsing het gewys dat die teenwoordigheid van wind die werkverrigting van LVSK's verminder. Daar was gevind dat kruiswinde (wind loodreg tot die langste sy van die LVSK) versteurde inlaat vloeitoestande veroorsaak, veral by waaiers wat aan die stroomop kant van die LVSK naby die simmetrievlak geleë is. Hierdie waaiers word blootgestel aan na wat verwys word as '2-D' windtoestande wat gekenmerk word deur vloeiwegbreking wat plaasvind by die stroomop rand van die waaierinlate. Eksperimentele ondersoeke van inlaat vloeiversteurings het hierdie toestande gesimuleer deur die waaier platformhoogte te verstel. Lae platform hoogtes het gelei tot hoër vlakke van inlaat vloeiversteuring, soortgelyk aan wat gevind word met hoë kruiswindsnelhede. Hierdie ondersoek gebruik numeriese en eksperimentele metodes om die werkverrigting van verskeie waaierkon gurasies (verteenwoordigend van kon- gurasies wat gebruik word in die Suid-Afrikaanse kragvoorsieningsindustrie) wat blootgestel word aan versteurde inlaat vloeitoestande te bepaal. Die ooreenkoms tussen platformhoogte en kruiswind e ekte word ook ondersoek en 'n korrelasie tussen die sisteem volumetriese e ektiwiteit, platformhoogte en kruiswindsnelheid word bepaal.
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Karve, Madhura Shreeram. "Numerical Analysis of Heat Transfer Enhancement and Pressure Drop Reduction for an A-frame Air Cooled Steam Condenser." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307440507.
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Howey, David A. "Thermal design of air-cooled axial flux permanent magnet machines." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5588.
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Accurate thermal analysis of axial flux permanent magnet (AFPM) machines is crucial in predicting maximum power output, and a number of heat transfer paths exist making it difficult to undertake a general analysis. Stator convective heat transfer is one of the most important and least investigated heat transfer mechanisms and therefore is the focus of the present work. Experimental measurements were undertaken using a thin-film electrical heating method based on a printed circuit board heater array, providing radially resolved steady state heat transfer data from an experimental rotor-stator system designed as a geometric mockup of a through-flow ventilated AFPM machine. Using a flat rotor, local Nusselt numbers Nu(r) = hR/k were measured across 0.6
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Haffejee, Rashid Ahmed. "Development of a process modelling methodology and condition monitoring platform for air-cooled condensers." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33706.
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Air-cooled condensers (ACCs) are a type of dry-cooling technology that has seen an increase in implementation globally, particularly in the power generation industry, due to its low water consumption. Unfortunately, ACC performance is susceptible to changing ambient conditions, such as dry bulb temperatures, wind direction, and wind speeds. This can result in performance reduction under adverse ambient conditions, which leads to increased turbine back pressures and in turn, a decrease in generated electricity. Therefore, this creates a demand to monitor and predict ACC performance under changing ambient conditions. This study focuses on modelling a utility-scale ACC system at steady-state conditions applying a 1-D network modelling approach and using a component-level discretization approach. This approach allowed for each cell to be modelled individually, accounting for steam duct supply behaviour, and for off-design conditions to be investigated. The developed methodology was based on existing empirical correlations for condenser cells and adapted to model double-row dephlegmators. A utility-scale 64-cell ACC system based in South Africa was selected for this study. The thermofluid network model was validated using site data with agreement in results within 1%; however, due to a lack of site data, the model was not validated for off-design conditions. The thermofluid network model was also compared to the existing lumped approach and differences were observed due to the steam ducting distribution. The effect of increasing ambient air temperature from 25 35 − C C was investigated, with a heat rejection rate decrease of 10.9 MW and a backpressure increase of 7.79 kPa across the temperature range. Condensers' heat rejection rate decreased with higher air temperatures, while dephlegmators' heat rejection rate increased due to the increased outlet vapour pressure and flow rates from condensers. Off-design conditions were simulated, including hot air recirculation and wind effects. For wind effects, the developed model predicted a decrease in heat rejection rate of 1.7 MW for higher wind speeds, while the lumped approach predicted an increase of 4.9 . MW For practicality, a data-driven surrogate model was developed through machine learning techniques using data generated by the thermofluid network model. The surrogate model predicted systemlevel ACC performance indicators such as turbine backpressure and total heat rejection rate. Multilayer perceptron neural networks were developed in the form of a regression network and binary classifier network. For the test sets, the regression network had an average relative error of 0.3%, while the binary classifier had a 99.85% classification accuracy. The surrogate model was validated to site data over a 3 week operating period, with 93.5% of backpressure predictions within 6% of site data backpressures. The surrogate model was deployed through a web-application prototype which included a forecasting tool to predict ACC performance based on a weather forecast.
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Kroger, Detlev G. "Air-cooled heat exchangers and cooling towers : thermal-flow performance evaluation and design." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49822.
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Thesis (PhD)--Stellenbosch University, 2004.ENGLISH ABSTRACT: During the last 30 years I have been involved in the theory and practice of thermal engineering and in particular, in the areas of air-cooled heat exchangers and cooling towers for the power, refrigeration, process and petrochemical industries in South Africa and internationally. During this period, I have authored and co-authored more than 120 papers that were published in technical journals or presented at conferences nationally or internationally. Most of these papers are included in a manuscript entitled "Air-cooled Heat Exchangers and Cooling Towers", in which Ipresent a systematic approach to the thermal performance evaluation and design of industrial air-cooled heat exchangers and cooling towers. This original publication also includes the relevant practice applicable to the design of cooling systems, based on my experience as a consultant to industry. Design offices throughout the world presently follow our design methods, or at least employ many of our research results. Our work has furthermore contributed to the development of improved cooling system designs (e.g. new dephlegmator header designs), components (e.g. single-row flattened finned tubes) and product improvement and quality control (e.g. performance testing and measurement of thermal contact resistance between fin and tube during production). Many of our research findings have found application in the modification of existing cooling systems. The manuscript has also been used as reference work during the presentation of short courses to practising engineers and consultants in industry and to engineering graduates at the University of Stellenbosch. A two-volume edition of this manuscript was published by PennWell Corp., Tulsa, Oklahoma, USA in 2004.
AFRIKAANSE OPSOMMING: Gedurende die laaste 30 jaar was ek betrokke by die teorie en praktyk van lugverkoelde warmteoordraers en koeltorings vir die kragopwekkings-, verkoelings-, proses- en petro-chemiesenywerhede in Suid-Afrika sowel as in die buiteland. Gedurende hierdie periode was ek outeur en mede-outeur van meer as 120 publikasies wat in tegniese tydskrifte, of by plaaslike of oorsese konferensies aangebied is. Die meeste van hierdie publikasies vorm deel van 'n manuskrip getiteld "Air-cooled Heat Exchangers and Cooling Towers" waarin ek 'n sistematiese benadering tot die bepaling van die termiese vermoë en ontwerp van industriële lugverkoelde warmteoordraers en koeltorings aanbied. Hierdie oorspronklike publikasie bevat ook die relevante praktyk wat van toepassing is op verkoelingsaanlegte. Ontwerpkantore wêreldwyd volg tans hierdie ontwerpsmetodes, of gebruik ten minste baie van ons navorsingsresultate. Ons werk het verder bygedra tot die ontwikkeling van verbeterde verkoelingsaanlegte (bv. nuwe deflegmatore), komponente (bv. enkelbuisry platvinbuise ) en verbeterde produkte en kwaliteitskontrole (bv. toetsing van verkoelingsvermoë oftermiese kontakweerstand tussen vin en buis gedurende produksie). Baie van ons bevindinge het toepassing gevind in die modifikasie van verkoelingsaanlegte. Die manuskrip is ook as verwysing gebruik gedurende die aanbieding van kort kursusse aan ingenieurs in die praktyk en aan nagraadse studente aan die Universiteit van Stellenbosch. 'n Twee-volume uitgawe van die manuskrip is deur PennWell Corp., Tulsa, Oklahome, VSA in 2004 gepubliseer.
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Sindayigaya, Oscar 1956. "A DESIGN ANALYSIS PROGRAM FOR SOLAR HEATED AND PASSIVELY COOLED HOMES IN BURUNDI." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276514.
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Two design analysis programs that model the performance of solar heated and passively cooled homes in the climate of BURUNDI are presented. The new programs, SOLBUDI and COLBUDI, are based on the design analysis programs SOLASEC and COOLASEC which have been modified to account for skylights, solar heat gains on wall and roof surfaces, as well as nocturnal radiation effects on the roof. Additionally, Bjumbura (∼ 800 meters in altitude) weather data and the thermal properties of building materials commonly used in Burundi are incorporated into the programs. Typical weather data for cities at mid-altitudes (∼ 1500 meters) and high altitudes (>2000 meters) are also presented. Due to the great variation in altitude (700 meters - 2600 meters) and climate in Burundi, both heating and cooling are required, hence the need for both heating (SOLBUDI) and cooling (COLBUDI) design analysis programs. Skylights, east windows, and west windows are the best sources of solar gain in Burundi due to the high solar angles, which are present all seasons. Thus, solar gains through these apertures must be controllable to prevent overheating during the warm season.
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Tipton, Russell C. "Simulation of a storage freezer operating with a binary nonazeotropic refrigerant blend part I. equation of state cycle selection compressor model and air-cooled condenser model." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182524272.
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Wang, Xichun. "Application of MPCM slurry with cooled ceiling to realize a low energy building design." online access from Digital Dissertation Consortium, 2008. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3341125.
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Ozdemir, Mehmet Ozan. "Optimum Design Of Parallel, Horizontal And Laminar Forced Convection Air-cooled Rectangular Channels With Insulated Lateral Surfaces." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610710/index.pdf.
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The objective of this thesis is to predict numerically the optimal spacing between parallel heat generating boards. The isothermal boards are stacked in a fixed volume of electronic package enclosed by insulated lateral walls, and they are cooled by laminar forced convection of air with prescribed pressure drop. Fixed pressure drop assumption is an acceptable model for installations in which several parallel boards in electronic equipment receive the coolant from the same source such as a fan.
In the numerical algorithm, the equations that govern the process of forced convection for constant property incompressible flow through one rectangular channel are solved. Numerical results of the flow and temperature field in each rectangular channel yield the optimal board-to-board spacing by which maximum heat dissipation rate from the package to the air is achieved. After the results of the optimization procedure are given, the correlations for the determination of the maximum heat transfer rate from the package and optimal spacing between boards are, respectively, derived in terms of prescribed pressure difference, board length, and density and kinematic viscosity of air.
In conclusion, the obtained correlations are compared and assessed with the available two-dimensional studies in literature for infinite parallel plates. Furthermore, existing two-dimensional results are extended to a more generalized three-dimensional case at the end of the thesis.
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Kulkarni, Rituja. "Parametric Study of a Thermal Energy Storage Module Coupled with a Heat Exchanger." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627666160707063.
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Drábek, Ivo. "Energetický zdroj se spalovací turbinou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230039.
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The goal of this master´s thesis is designing power plant with gas turbine of 50 MWe power output for the site. It includes appropriete choose of gas turbine and its simplified termodynamic calculation, designing the thermal diagram and its calculation, for the parameters complying with nominal temperature of outside air, layout design, annual energy and mass flow results, savings of combined heat and power, intended at this application and economic evaluation of investment.
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Young, Ryan F. "Utilization of a Neural Network to Improve Fuel Maps of an Air-Cooled Internal Combustion Engine." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1282143527.
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Arcilesi, David J. Jr. "Developmental Analysis and Design of a Scaled-down Test Facility for a VHTR Air-ingress Accident." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338387523.
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Bochníček, Ondřej. "Vzduchem chlazený kondenzátor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318861.
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This master´s thesis deals with an air cooled condenser. The specific attention is focused on the condenser in the Brno´s waste-to-energy plant SAKO. The general process of calculation of the heat transfer coefficient is introduced, which is the base for the calculation of the condenser´s output. This process is later used for the calculation of a specific condenser. A considerable part of the thesis is concentrated on the analysis of behavior of the condenser of SAKO in various conditions from the theoretical point of view and then also in terms of real operation using provided operational data.
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Wu, Buo-Ming, and 吳柏旻. "The Experimental Study of Air Cooled Condenser and The Development of Computer Aided-Design Softwares." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/33093703966571342747.
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碩士國立成功大學
機械工程學系碩博士班
93
This study was focused on the investigation of air-cooled condensers, including two main parts as expressed in the following. First, the open wind tunnel was used to study the circular and oval fin air-cooled condensers experimentally. These air-cooled condensers involved the ratios (Ar) of its minor axis to major axis are 1, 2.5, 2.8, and 3.1, respectively. The relationships between the Colburn factor j and the Reynolds number/the ratio (Ar) were presented. Moreover, the relationships between the friction factor and the Reynolds number/the ratio (Ar) were also presented. Second, there is an interactive computer-aided design software for the air-cooled condensers was developed. It has been written by Visual Basic 6.0 and can be run in any personal computer. The software has the following two functions: (1) Predicting the performance of a radiator when the dimensions are given. (2) Determining the necessary size of a radiator when given the required performance. At last, the experimental results were demonstrated by the computer-aided design software. The results show that the efficiency of circular air-cooled condenser is better than oval air-cooled condenser.
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Chen, Chih-Lin, and 陳智霖. "Fluid-Dynamic Diagnostics in Air-Cooled Condenser Using DPIV and HPIV." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/17096711028768853738.
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碩士南台科技大學
機械工程系
93
Air-cooled condenser (ACC) is quite common in the heat transfer application, and the researches of local heat flow characteristic are also quite a lot. Most methods to improve hydrothermal effect are to increase the transfer area and reduce the pressure drop. The part I of the experiment will be used a digital particle image velocimetry (DPIV) system to measure instantaneous and non-invasive ensemble-averaged flow fields inside the glass curtain of the ACC. Particularly for the reduced scale test section of ACC that are used in incinerator, we are used to observe the streamline distributions at the middle plane inside the glass curtain in various inlet velocity of the blowers for the one-row, two-row, three-row ACC and the glass curtain with and without holes. In order to analyze deeply the flow field characteristic of atmospheric condenser, the part II of the experimental test section is designed to arrange 3-row staggered elliptic finned-tube which the major/minor axis ratios are 2.8. Four different kinds of hole-type of glass curtain are used to be the structure of the experimental model. And it is experimental apparatus to utilize a high particle image velocimetry (HPIV) system to control the change of flow field in a very minimum time. Also, it is discussed in detail that the flow field inside and outside the curtain is divided into four kinds of observation plane. The experimental result shows that the structure of flow field of not hole the glass curtain forms the boundary layer separation on the surface of steam dust, and results in low-speed region field; In addition, because of the turbulent stagnate vortex flow, it has the chimney effect when approaching the outer wall curtain. The holes for ACC would be effective to reduce detained vortex and the shape parameter (hole-type) affects heavier than power parameter (inlet wind velocity). Among them, it is the most effective method to improve the back flow between the curtain outer wall and ACC. It can have better effect of thermal-hydraulic.
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Wei, Li-Fan, and 魏立帆. "The Analysis of The Flow Characteristics for Incinerator Air-Cooled Condenser." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/12419911610261847402.
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碩士國立成功大學
機械工程學系碩博士班
93
Numerical method was used to predict velocity, temperature distribution in the incinerator air-cooled condenser, and the flow characteristics in the glass wall were also discussed in this study. In the 2-D numerical analytical method with original size model, try to change the height of the glass wall and the area of hole. In the 3-D numerical analytical methods with reduced size model, try to change the area of hole. The DPIV (Digital Particle Image Velocimetry) was also carried out in a reduced size model to compare the flow field s with the numerical results. The experiment was used the DPIV with reduced size model to pick up a 2-D velocity field. we used two kinds of wall, which one has no hole and the other has two holes. The results indicated that the airflow move off the glass wall, it will spread into the atmosphere. When the glass wall has two holes, the part of airflow will pass through the holes. Compare with the 3-D numerical analytical and the experiment, the results were similar. The Navier-Stokes equations with the energy equations were solved in this study. The SIMPLEC algorithm with finite volume based scheme was used in this numerical analysis. The results indicated that the height of the glass wall and the area of hole will influence temperature distribution in the glass wall, heighten the height of the glass wall and magnify the area of hole can reduce temperature in the glass wall of the incinerator air-cooled condenser.
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Li, Hong-wun, and 李宏文. "The 3-D Thermal-Hydraulic Analysis of Elliptic Finned Air-Cooled Condenser." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/18889778596790235468.
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碩士國立成功大學
機械工程學系碩博士班
92
The numerical analysis was carried out to study the 3- D heat transfer and flow in finned tube heat exchanger of Air-cooled condenser. Three kinds of major/mirror axis ratios (2.5、2.8 and 3) are examined for the elliptic finned-tube heat exchangers and the results are also compared with the corresponding circular finned-tube having the same perimeter. Numerical simulation was performed by 3-D turbulence analysis with conjugated heat transfer and fluid flow. The numerical results for the temperature、pressure 、Nusselt number and fanning friction factor at various inlet frontal velocities(1~5 m/s) are shown and compared with the available experimental data. The numerical result indicated that the pressure drop of circular finned-tube heat exchanger is 3 times of elliptic finned-tube heat exchanger, while the heat transfer coefficient of circular finned-tube is 1.1 times of elliptic finned-tube. The heat transfer coefficient per unit of pressure drop for elliptic finned-tube(Ar = 3.1) is 1.08 times of elliptic finned-tube(Ar = 2.8) 、1.24 times of elliptic finned-tube(Ar = 2.5) and 2.6 times of circular finned-tube.
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Chu, Yu-Hsien, and 朱郁賢. "An Experimental Study of Heat Transfer in Air-Cooled Condenser with R-134a Medium." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/24016465944659216427.
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Liu, Jen-Hao, and 劉人豪. "A Study of Air-Cooled Condenser and Optimum Performance for Solar-Assisted Ejector Cooling/Heating System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/37887772133345105361.
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碩士臺灣大學
機械工程學研究所
98
A solar-assisted ejector cooling/heating system (SACH-k1) was developed in the present study. SACH-k1 includes three systems, ejector cooling system, inverter-type air conditioner and solar heating system. The cooling effect of ECS generated by solar heat is used to cool the condenser of the A/C, then increase A/C’s COP and reduce the power consumption of the compressor. It has been noted that ejector cooling system should be designed using an air-cooled condenser in hot climate area because of the water shortage. Thus, SACH-k1 is developed for this purpose and the design details are shown in paper. To utilize solar energy, the liquid level of SACH’s generator needs to be controlled precisely. A liquid level control system is developed in the present study, so that SACH can overcome unstable effect due to generator temperature changes caused by variation of solar irradiation. Further, running cost of ejector cooling system is too high to apply. This study proposes the idea of ejector’s backpressure optimal control and realizes the idea by the optimal control system. As a result, the operating power consumption is decreased about 60%.
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Guan-ShianLu and 盧冠憲. "The Inlet Channel Design for an Air-Cooled Scooter Engine." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/49bkyn.
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碩士國立成功大學
機械工程學系
106
In this study, a 3-D numerical air-cooling channel model of a 163c.c four stroke single cylinder scooter engine is established and evaluated through computational fluid dynamics(CFD) with a conjugated heat transfer scheme to show the temperature distribution of the engine. The flow field is also observed, and the correlation between the heat transfer performance and flow field is discussed. In order to observe the real flow field inside the engine shroud, we also establish a transparent engine shroud model through 3-D printer. In view of the temperature around the spark plug hole is too high; thus, we try to improve the two features on the shroud, which are deflector and concave. We first improve the height of the deflector on the shroud. There are 5 cases in discussion. Then, we try to change the anther feature, width of the concave. There are 4 cases in discussion. The result shows the temperature around the spark plug hole and temperature differences on different fins. We find the optimal design of the air-cooling channel, which has the lowest temperature around the spark plug hole and better temperature difference on the fins.
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Wang, Sheng-Kai, and 王聖凱. "CFD Simulation for Innovative Condensing Coil Design of Air-Cooled Chillers." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/58n8rr.
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碩士國立臺北科技大學
能源與冷凍空調工程系碩士班
96
The primary purpose of this research is as follows: Utilizing the CFD simulation and heat exchange conducting analysis, in lieu of traditional condensing coil of air-cooled liquid chiller distributes air flow unevenly and unsteadily, to devise seven innovative coils and to discuss the influence of such inventions on the flow circulation in the air-cooled liquid chiller, in order to find the best configuration which would lead to improved heat transfer efficiency of the condenser and in turn increase the machine''s overall efficiency. Research results show that by changing the fin pitch on the tube plate, it can only lower total cost, but it does not increase volume of heat transferred, nor does it stabilize face velocity inside and outside of the tube plate. The change in heat transfer is also neglectable. Changing fin pitch of coil arrangement best results in case D2. Compared to those of case A, the average velocity and heat transfer increased by 13.51% and 3.23% respectively; and 3.86% increase in average velocity but 0.51% decrease in heat transfer compared to results in case C. By changing the tube row arrangement of coil, it helps distribute face velocity of the condensing coil more evenly among the inside and outside of the condensing coil. Case F appears to be the best configuration. It improves face velocity distribution and stabilizes average face velocity on the inside and outside of the condensing coil. The results of this case show an increase in average face velocity of 20.42% and a 10.28% increase in total heat transfer compared to those in case A; and a 9.59% and 4.9% respective improvement compared to case C.
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ANDREAN, KIKI, and 齊安睿. "Study on the Development and Design of Air-Cooled for Feed Drive System." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f9md6v.
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碩士國立勤益科技大學
機械工程系
107
High feed rate, high precision, and high accuracy are the main factors that need to maintain from manufacturing machines, especially the feed drive system. However, besides the increasing of temperature, also by the test of laser measurement, the error value of repeatability, accuracy, and backlash are going to increase when thermal occurs caused by friction between components when the feed drive system working under high feed rate and long working time. The friction between components that occurs especially on both of ball bearing minimized by giving the air cooling process which controlled by Micro Controller Unit (MCU) to maintain the best value of accuracy, repeatability, and backlash while the feed drive system is working. The cooling process that is given to the system decreasing the temperature on both bearings and ball screw elongation. Although the system is given a cooling process, the temperature of the nut continues to increase. However, the increasing of the nut temperature is lower when using the cooling process than without the cooling process. The decreasing of nut temperature is 29.6% for feed rate 10000m/min, 45.8% for feed rate 15000m/min, and 43% for feed rate 18000m/min. The higher decreasing error value of accuracy, repeatability (R+), and repeatability (R-) when the system using feed rate 15000m/min under cooling process, respectively 31.4%, 63.8%, and 61.2%. Loading that given to the system also influences the error value of accuracy and backlash under low and high feed rate. The error value of accuracy and backlash will increase proportionally with increasing loading that given. However, when the system gives cooling process under high loading with the feed rate 15000m/min, the error value of accuracy, backlash, repeatability (R+), and repeatability (R-) is decrease, respectively 18.88%, 46.8%, 37.99%, and 44.06%.
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Faulkner, Jacob Christopher. "A Thermal Feasibility Study and Design of an Air-cooled Rectangular Wide Band Gap Inverter." 2011. http://trace.tennessee.edu/utk_gradthes/870.
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All power electronics consist of solid state devices that generate heat. Managing the temperature of these devices is critical to their performance and reliability. Traditional methods involving liquid-cooling systems are expensive and require additional equipment for operation. Air-cooling systems are less expensive but are typically less effective at cooling the electronic devices. The cooling system that is used depends on the specific application.
Until recently, silicon based devices have been used for the solid-state devices in power electronics. Newly developed silicon-carbide based wide band gap devices operate at maximum temperatures higher than traditional silicon devices. Due to the permissible increase in operating temperatures, it has been proposed to develop an air-cooling system for an inverter consisting of silicon carbide devices.
This thesis presents recent research efforts to develop the proposed air-cooling system. The thermal performance of the each design iteration was determined by numerical simulations via the finite element method in both steady state and transient mode using COMSOL Multi-physics software version 3.5a. For all simulations presented in this thesis, the heat dissipated in the MOSFETS and diodes are specified as functions of current, voltage, switching frequency, and junction temperature. For both the steady state and transient simulations, the junction temperature was determined iteratively. Additionally in the transient simulations, the current distribution is a function of time and was deduced from the EPA US06 drive cycle. After several design iterations, a thermally feasible design has been reached. This design is presented in detail in this thesis.
Under transient simulations of the final design, the maximum junction temperatures were determined to be below 146 ºC for air flow rates of 30 and 60 CFM, which is substantially lower than the 250 ºC maximum allowable junction temperature of Si-C devices. However for steady state simulations, junction temperatures were found to be much higher than the transient simulations. It was determined that a minimum flow rate of 50 CFM is required to meet the temperature requirements of the Si-C devices under steady state operating conditions. The power density of this air-cooled final design is 11.75 kW/L, and it is competitive with liquid-cooled systems.
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Mueller, Stephanie I. "Model and design of an air-cooled thermal management system for an integrated motor-controller." 2005. http://catalog.hathitrust.org/api/volumes/oclc/62156610.html.
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Huang, Shiao-Teng, and 黃孝登. "Discussion about Design and Production and Performance of Air-Cooled Proton Exchange Membrane Fuel Cell Controller." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/86422931223824631005.
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碩士國立勤益科技大學
冷凍空調系
103
This study produces a Proton Exchange Membrane Fuel Cell (PEMFC) controller, a 500W fuel cell is used for performance testing and comparison. First, the commercially available fuel cell controller and self-made fuel cell controller with commercially available 500W fuel cell are tested, there are three parts. Part 1 tests the purge of the self-made controller under different loads, the optimal corresponding Purge under low, medium and high loads is found. Part 2 discusses the performance of self-made controller and commercially available controller, and the performance is compared with the commercially available controller according to the optimum Purge under various loads in Part 1. Part 3 tests the hydrogen usage rate of self-made controller and commercially available controller, the constant power is used for experiment. The test results show that the hydrogen usage rate can be reduced effectively under low and medium loads. Under medium and high loads, the fuel cell can purge and maintain output performance effectively, and the hydrogen usage rate is slightly different from the commercially available controller. This paper also implements PEMFC runner design and test, bipolar runner design and flow direction analysis and single cell stack experiment, so as to provide reference data for the future research.
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Prinsloo, Lionel. "A critical evaluation of the design of removable cover-plate header boxes for air-cooled heat exchangers." Diss., 2011. http://hdl.handle.net/2263/28133.
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Large air-cooled heat exchangers (ACHEs) are most popularly implemented in the petrochemical and power industries at arid locations. They operate on a simple concept of convective heat transfer, whereby air in the surrounding atmosphere is caused to flow across a tube bundle, which in turn transports a process fluid. The distribution and direction of the process fluid flow may furthermore be guided via a set of appropriately located header boxes, which essentially consist of a collection of welded flat plates and nozzle attachments. Perforations on one of the faces of these boxes serve as an interface to the tube bundle. The overall design and construction of an ACHE is commonly regulated by an American Petroleum Institute (API) standard, which is required to be used in conjunction with acceptable design codes. In spite of this, the design of certain header box configurations remains of prominent concern. It is the focus of the present study to investigate the approach adopted for a header box variant labelled as the removable cover type. In this configuration, one of the plates used to construct the header box is fastened and sealed by a collection of bolted joints and a gasket, allowing it to be removed. One appropriate design code for the header box equipment is the ASME (American Society of Mechanical Engineers) boiler and pressure vessel code. However, it provides no specific approach pertaining to the removable cover design. Instead it has been commonplace in industry for a number of aspects from this code to be synthesized, together with a collection of assumptions surrounding the header box behaviour, into an all encompassing design by rule approach. In this approach, the header box behaviour is accepted as being planar, whilst circumstances such as nozzle attachments and associated loading would suggest that a more comprehensive approach should be undertaken. The aim of the present study is therefore to critically evaluate the current practice, and establish its adequacy. To do so, a detailed three-dimensional finite element model (FEM) of an example header box design is developed. Subsequent comparisons with the stress distribution predicted via current practice show that the existing analytical model gives inaccurate and, in cases, overly conservative results. A new analytical approach developed from rigid frame theory is demonstrated to provide improved correlation with FEM. The linear elastic design by analysis approach, presented in the ASME code, is also utilised as a method for establishing design adequacy. Results obtained via design by analysis incorporating the finite element method are shown to be less conservative than those arising from design by rule methods. The design by analysis approach is also used to conduct a more detailed investigation of nozzle placement and external loading. In general, the effect of including a nozzle did not result in a significant increase in side plate stress, with failure more likely to occur within the nozzle wall.Dissertation (MEng)--University of Pretoria, 2011.
Mechanical and Aeronautical Engineering
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