Steam flow distribution in air-cooled condensers

Zipfel, Toni (1996-03)

Thesis (MEng)--Stellenbosch University, 1996.

Thesis

ENGLISH ABSTRACT: In this thesis the parameters affecting the steam flow distribution through an air-cooled steam condenser, as found in power generating plants is investigated. The investigated condenser configuration consists of bundles with single rows of tubes. It is required to design the air-cooled condenser in such a way that the flow through each individual finned tube is sufficient to allow the entering steam to condense partially or fully along the full length of the tube. Thereby the accumulation of non-condensible gases is prevented, that may otherwise form so-called dead zones which reduce the thermal efficiency of the condenser. A thorough experimental study was performed to determine the inlet loss coefficients of the finned tubes. These were found to vary as a function of the position of the finned tube, the steam velocity in the header and the geometrical configuration of the inlets themselves. Subsequently the flow pattern on the steam-side of air-cooled condensers, consisting of bundles with single rows of finned tubes, was analyzed. It is shown that by following this approach, a condenser can be designed in which the formation of any dead zones can be avoided. The flow distribution through an air-cooled condenser section was also determined numerically with the aid of a finite difference computer code. The results of this numerical analysis confirm the validity of the proposed design method.

AFRIKAANSE OPSOMMING: In hierdie tesis word die parameters ondersoek wat die stoomvloeiverdeling deur 'n lugverkoelde kondenser, soos gevind in kragsentrales, beïnvloed. Die kondenser konfigurasie bestaan uit bundels met enkelrye vinbuise. Die kondenser moet sodoende ontwerp word dat die stoomvloei by elke afsonderlike vinbuis inlaat groot genoeg is, om gedeeltelik of volkome oor die buis se volle lengte sal kondenseer. Daarmee word die opeenhoping van onkondenseerbare gasse wat sogenaamde dooie zones kan vorm wat die termiese benuttingsgraad van die kondenser verlaag, voorkom. 'n Deeglike eksperimentele studie is deurgevoer om die inlaatverlieskoëffisiënte van die vinbuise te bepaal. Daar is gevind dat hierdie inlaatverlieskoëffisiënte as 'n funksie van die posisie van die vinbuis, die snelheid in die verdeelpyp en die geometriese uitleg van die inlate varieer. 'n Stoomkantontwerpsbenadering van 'n lugverkoelde stoomkondenser, wat uit bundels met 'n enkelry vinbuise bestaan, is in hierdie werk ondersoek. Met hierdie benadering word die kondenser ontwerp om die formasie van dooie sones te vermy. Verder is die vloeiverdeling deur 'n lugverkoelde kondenserseksie bereken, deur gebruik te maak van 'n numeriese eindige-verskille-rekenaarprogram. Die resultate van hierdie numeriese analise bevestig die geldigheid van die voorgestelde ontwerpsmetode.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/55240
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