Development of a triple stage heat transformer for the recycling of low temperature heat energy

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dc.check.embargoformatNot applicableen
dc.check.infoNo embargo requireden
dc.check.opt-outNot applicableen
dc.check.reasonNo embargo requireden
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dc.contributor.advisorByrne, Edmond P.en
dc.contributor.advisorCronin, Kevinen
dc.contributor.authorDonnellan, Philip
dc.contributor.funderIrish Research Council for Science Engineering and Technologyen
dc.date.accessioned2015-10-23T09:14:55Z
dc.date.available2015-10-23T09:14:55Z
dc.date.issued2014
dc.date.submitted2014
dc.description.abstractAbsorption heat transformers are thermodynamic systems which are capable of recycling industrial waste heat energy by increasing its temperature. Triple stage heat transformers (TAHTs) can increase the temperature of this waste heat by up to approximately 145˚C. The principle factors influencing the thermodynamic performance of a TAHT and general points of operating optima were identified using a multivariate statistical analysis, prior to using heat exchange network modelling techniques to dissect the design of the TAHT and systematically reassemble it in order to minimise internal exergy destruction within the unit. This enabled first and second law efficiency improvements of up to 18.8% and 31.5% respectively to be achieved compared to conventional TAHT designs. The economic feasibility of such a thermodynamically optimised cycle was investigated by applying it to an oil refinery in Ireland, demonstrating that in general the capital cost of a TAHT makes it difficult to achieve acceptable rates of return. Decreasing the TAHT's capital cost may be achieved by redesigning its individual pieces of equipment and reducing their size. The potential benefits of using a bubble column absorber were therefore investigated in this thesis. An experimental bubble column was constructed and used to track the collapse of steam bubbles being absorbed into a hotter lithium bromide salt solution. Extremely high mass transfer coefficients of approximately 0.0012m/s were observed, showing significant improvements over previously investigated absorbers. Two separate models were developed, namely a combined heat and mass transfer model describing the rate of collapse of the bubbles, and a stochastic model describing the hydrodynamic motion of the collapsing vapour bubbles taking into consideration random fluctuations observed in the experimental data. Both models showed good agreement with the collected data, and demonstrated that the difference between the solution's temperature and its boiling temperature is the primary factor influencing the absorber's performance.en
dc.description.sponsorshipIrish Research Council for Science Engineering and Technology (EMBARK initiative)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationDonnellan, P. 2014. Development of a triple stage heat transformer for the recycling of low temperature heat energy. PhD Thesis, University College Cork.en
dc.identifier.endpage240
dc.identifier.urihttps://hdl.handle.net/10468/2006
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2014, Philip Donnellan.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectEnergyen
dc.subjectAbsorptionen
dc.subjectBubblesen
dc.subjectHeat transformeren
dc.subjectTriple absorption heat transformeren
dc.subjectWaste heaten
dc.subjectEnergy recyclingen
dc.subjectBubble columnen
dc.subjectRandom processesen
dc.subjectMass transferen
dc.thesis.opt-outfalse
dc.titleDevelopment of a triple stage heat transformer for the recycling of low temperature heat energyen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePHD (Engineering)en
ucc.workflow.supervisore.byrne@ucc.ie
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