A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers

The thesis describes the results of a research programme involving both experimental and modelling work to study evaporation on the shellside of shell-and-tube heat exchangers. The particular focus is on the study of evaporation over a range of mass fluxes typical of operating practice. Current desi...

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Main Author: Doo, Gavin H.
Published: University of Strathclyde 2005
Subjects:
Online Access:http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417350
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spelling ndltd-bl.uk-oai-ethos.bl.uk-4173502015-04-03T03:20:33ZA modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangersDoo, Gavin H.2005The thesis describes the results of a research programme involving both experimental and modelling work to study evaporation on the shellside of shell-and-tube heat exchangers. The particular focus is on the study of evaporation over a range of mass fluxes typical of operating practice. Current design procedures make simplifying assumptions (such as a uniform gas/liquid distribution across the entire cross section of the shellside) which are thought to be inaccurate. The experimental work was conducted on a TEMA E-type shell and tube evaporator. The evaporator has 97 tubes of length 1240 mm, and the unit is large enough to represent full-scale industrial exchangers. Geometrical considerations such as baffle orientation and presence of sealing strips were also tested. The results show that there is a drop in the heat transfer performance at lower mass fluxes and higher vapour outlet qualities. It is suggested that the sudden drop in heat transfer performance at lower mass fluxes is caused by a change in flow pattern on the shellside of the heat exchanger. Evidence suggests that there is a possible transition from a homogeneous to a stratified two-phase flow. Support for this conclusion is that the transition in heat transfer performance appears to coincide with a change in the behaviour of the measured two-phase pressure drop multiplier. The thesis also describes the development of a model for shellside heat transfer and pressure drop which allows for the effects of separated flow and also attempts to predict the apparent transition in two-phase flow pattern. Knowledge of the existence of the transition and its prediction is important in avoiding unexpected poor performance in practice. A close correspondence is found when the predictions from the developed model are compared with the data from the experimental programme.621.4022University of Strathclydehttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417350http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21570Electronic Thesis or Dissertation
collection NDLTD
sources NDLTD
topic 621.4022
spellingShingle 621.4022
Doo, Gavin H.
A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
description The thesis describes the results of a research programme involving both experimental and modelling work to study evaporation on the shellside of shell-and-tube heat exchangers. The particular focus is on the study of evaporation over a range of mass fluxes typical of operating practice. Current design procedures make simplifying assumptions (such as a uniform gas/liquid distribution across the entire cross section of the shellside) which are thought to be inaccurate. The experimental work was conducted on a TEMA E-type shell and tube evaporator. The evaporator has 97 tubes of length 1240 mm, and the unit is large enough to represent full-scale industrial exchangers. Geometrical considerations such as baffle orientation and presence of sealing strips were also tested. The results show that there is a drop in the heat transfer performance at lower mass fluxes and higher vapour outlet qualities. It is suggested that the sudden drop in heat transfer performance at lower mass fluxes is caused by a change in flow pattern on the shellside of the heat exchanger. Evidence suggests that there is a possible transition from a homogeneous to a stratified two-phase flow. Support for this conclusion is that the transition in heat transfer performance appears to coincide with a change in the behaviour of the measured two-phase pressure drop multiplier. The thesis also describes the development of a model for shellside heat transfer and pressure drop which allows for the effects of separated flow and also attempts to predict the apparent transition in two-phase flow pattern. Knowledge of the existence of the transition and its prediction is important in avoiding unexpected poor performance in practice. A close correspondence is found when the predictions from the developed model are compared with the data from the experimental programme.
author Doo, Gavin H.
author_facet Doo, Gavin H.
author_sort Doo, Gavin H.
title A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
title_short A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
title_full A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
title_fullStr A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
title_full_unstemmed A modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
title_sort modelling and experimental study of evaporating two-phase flow on the shellside of shell-and-tube heat exchangers
publisher University of Strathclyde
publishDate 2005
url http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417350
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