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Author:Haavisto, Valtteri
Title:Levylämmönsiirrin alipainelauhduttimena
Vacuum steam condensation in plate heat exchanger
Publication type:Master's thesis
Publication year:2010
Pages:78      Language:   fin
Department/School:Energiatekniikan laitos
Main subject:Energiatalous ja voimalaitostekniikka   (Ene-59)
Supervisor:Ahtila, Pekka
Instructor:Sonninen, Jyrki
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  4862   | Archive
Keywords:condensation
plate heat exchanger
vacuum
heat transfer correlations
lauhtuminen
levylämmönsiirrin
alipaine
lämmönsiirtokorrelaatiot
Abstract (eng): This master thesis studies vacuum steam condensation in a plate heat exchanger and modelling of a heat transfer coefficient of condensation with different correlations.
Primary object of the research is to find out the effects of the hydraulic diameter and condensation pressure in vacuum conditions for the Vahterus plate and shell heat exchanger.

The thesis consists of theoretical part, which includes theory of the condensation and special characters of plate heat exchangers.
Moreover, the industrial use of vacuum condensers is studies in chapter four and the results are used in experimental tests.

Experimental part of the research was made at the test facilities of Vahterus.
The test included condensation tests with 0,05 - 0,3 bar(a) water vapour.
The plate heat exchanger construction was varied during the test by changing the hydraulic diameter of the heat transfer plate.
Seven different heat transfer correlations were adjusted to the studied heat exchanger.

It was found in the experimental tests that small condensation pressure decreases the condensation heat transfer coefficient.
Also it was found that increasing the hydraulic diameter has an increasing effect on heat transfer coefficient in vacuum conditions.
The main reason for heat transfer coefficient variation was discovered to be the steam flow velocity.

Correlations made for condensation were not observed to give wide convergence with the measurements although some correlations could forecast the condensation heat transfer coefficient correctly with certain condensation pressure and plate structure.

The plate heat exchanger can be suggested to vacuum condensation when condensation pressure is over 0,1 bar(a) and end-user has a small or middle size vacuum condenser.
The wide-ranging use of the plate condenser in vacuum conditions will need further investigation of hydraulic diameter to discover the most suitable ration between hydraulic diameter and condensation pressure.
Abstract (fin): Tässä diplomityössä tutkitaan levylämmönsiirtimen käyttöä alipainelauhduttimena ja lauhtumisen lämmönsiirtokertoimen mallintamista eri korrelaatioilla.
Työn tärkein tavoite on tutkia levylämmönsiirtimen hydraulisen halkaisijan ja lauhtumispaineen vaikutusta alipaineolosuhteissa Vahterus Oy:n levylämmönsiirtimessä.

Työ koostuu teoreettisesta osasta, jossa käsitellään lauhtumisen lämmönsiirron teoriaa ja levylauhduttimen erikoispiirteitä alipaineolosuhteissa.
Lisäksi työssä tutkitaan alipainelauhduttimien käyttöä teollisuuden eri sovelluksissa ja sovelletaan saatuja tietoja lauhdutintestiin.

Tutkimuksen kokeellinen osa toteutettiin Vahterus Oy:n laboratoriossa.
Kokeellisessa osassa levylämmönsiirtimessä lauhdutettiin 0,05 - 0,3 bar(a):sta vesihöyryä eri höyryn massavirroilla.
Kokeellisessa osassa käytettiin lauhduttimessa kahta eri lämmönsiirrinlevyä, joissa oli eri hydrauliset halkaisijat.
Seitsemää tutkittua lauhtumisen lämmönsiirtokorrelaatiota sovitettiin tutkittavaan lauhduttimeen saatujen mittaustulosten perusteella.

Kokeellisissa mittauksissa havaittiin lauhtumispaineen kasvamisen parantavan lauhtumisen lämmönsiirtokerrointa ja suuremman hydraulisen halkaisijan soveltuvan paremmin matalapaineisen vesihöyryn lauhduttamiseen.
Lauhtuvan höyryn virtausnopeuden havaittiin olevan ratkaiseva hyvän lämmönsiirron kannalta.

Lauhtumiselle laadittujen lämmönsiirtokorrelaatioiden ei havaittu antavan kattavaa yhtenevyyttä mittauksien kanssa, vaikka osa korrelaatioista mallinsi tietyt kohdat mittauksista täysin oikein.

Tutkimusten perusteella voidaan levylämmönsiirtimen jatkokäyttöä alipainelauhtumisessa suosittaa yli 0,1 bar(a):n lauhtumispaineessa pienille ja keskisuurille teollisuuden ja yhteiskuntien energiantuotannon lauhdekoneille.
Tämä edellyttää testissä saavutettujen hydraulisen halkaisijan vaikutuksen lisätutkimusta ja oikean lauhtumispaineen ja hydraulisen halkaisijan suhteen löytämistä.
ED:2011-01-10
INSSI record number: 41475
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