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dc.contributor.authorMurray, Portia
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date2015-01-04 12:05:13.982en
dc.date.accessioned2015-01-06T20:12:08Z
dc.date.available2015-01-06T20:12:08Z
dc.date.issued2015-01-06
dc.identifier.urihttp://hdl.handle.net/1974/12681
dc.descriptionThesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2015-01-04 12:05:13.982en
dc.description.abstractThis study focuses on the experimental testing and numerical modeling of a 4.5 kW transcritical CO2 heat pump water heater at Queen’s University in the Solar Calorimetry Laboratory. Due to the predicted high heat rejection temperatures in a transcritical vapour-compression cycle, buoyancy driven thermosyphon flow through a brazed-plate gas-cooler was proposed to promote tank stratification and to improve system performance. The performance was evaluated through a series of experimental sensitivity and static tank charge tests. A TRNSYS model was also created and verified to simulate the performance of the system under a detailed user demand schedule for a week of operation. The TRNSYS model used a parametric table created with a steady-state model of the vapour-compression system in EES that was validated against experimental data to a standard error of the Y-estimate of ±0.073 kW for heating capacity, ±1.01°C for gas-cooler exit temperature, and ±0.086 for COP. A series of tank charge tests were conducted under thermosyphon flow and forced flow rates at 1 L/min, 2 L/min, and 4 L/min. The thermosyphon charge test produced the highest level of stratification and a total COP of 3 at an average flow rate of 0.73 L/min. All of the forced convection cases operated with a higher degree of mixing. TRNSYS model simulations with hot water draws found that the thermosyphon flow configuration performed with a higher degree of stratification under regular user demand while simulations with high flow rates resulted in a mixed tank at a high temperature. Results predicted an 11% reduction in required heat energy input to the storage, a 30% reduction in electrical energy consumption, a 35% reduction in heat loss, and a 29% improvement in COP for the thermosyphon test as compared to the operation with a mixed tank at 4 L/min. The thermosyphon draw test also performed with the lowest average tank temperature, yet produced the highest draw temperatures. Through these results, it was concluded that natural convection operation with brazed-plate gas-coolers can contribute to a better performing system and this flow configuration should be considered in future applications of this technology.en_US
dc.languageenen
dc.language.isoenen_US
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectHeat Pumpen_US
dc.subjectWater heatingen_US
dc.subjectCO2en_US
dc.titlePerformance Analysis of a Transcritical CO2 Heat Pump Water Heater Incorporating a Brazed-Plate Gas-cooleren_US
dc.typethesisen_US
dc.description.degreeMasteren
dc.contributor.supervisorHarrison, Stephen J.en
dc.contributor.departmentMechanical and Materials Engineeringen


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