DEVELOPMENT OF A COMPACT HEAT EXCHANGER WITH BIFURCATED BARE TUBES

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dc.contributor.advisorRadermacher, Reinharden_US
dc.contributor.authorHuang, Zhiweien_US
dc.contributor.departmentMechanical Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2018-01-25T06:31:02Z
dc.date.available2018-01-25T06:31:02Z
dc.date.issued2017en_US
dc.description.abstractHeat transfer enhancement of air-to-fluid heat exchangers by novel surface or geometry design and optimization is a major research topic. The traditional way of reducing airside thermal resistance is to extend airside heat transfer area by adding fins and the conventional method of reducing fluid side thermal resistance is to use enhanced inner surfaces. These approaches have limitations in further reducing the thermal resistance. Small diameter (4 and 5 mm) fin-and-tube heat exchangers, louvered fin mini-channel heat exchangers (MCHX), newly studied round bare tube heat exchangers (BTHX) and shape optimized bare tube heat exchangers (sBTHX) with diameter of 0.8~1.0 mm were experimentally investigated using air and water to gain the fundamental understanding of heat transfer and the current technology limitations. Correlations of air-side heat transfer coefficient and pressure drop were then developed for BTHX and sBTHX. To improve current technologies, a novel bifurcated bare tube heat exchanger (referred as bBTHX, hereafter) was proposed in this study. It was numerically investigated and optimized using Parameterized Parallel Computational Fluid Dynamics (PPCFD) and Approximation Assisted Optimization (AAO) techniques. The most unique feature of bBTHX is the addition of bifurcation, which enhances airside heat transfer by creating 3D flow and waterside heat transfer by boundary layer interruption and redevelopment. The airside and waterside pressure drop can also be reduced by proper design and optimization, resulting in smaller fan and pumping power. Compared to MCHX with similar capacity and frontal area, the optimal bBTHX design has 38% lower total power and 83% smaller volume and 87% smaller material volume. Compared to BTHX with similar capacity and frontal area, the optimal design has 28% lower total power and 11% smaller volume and 10% smaller material volume. The bBTHX design can be widely applied in industry such as automotive radiators, oil coolers, condenser and evaporator. Two applications of this heat exchanger were discussed in detail: car radiator and indoor coil for Hybrid Variable Refrigerant Flow (HVRF) system. The bBTHX car radiator has 30% lower pumping power, 68% smaller heat exchanger volume and 67% less water weight than those of baseline. Moreover, refrigerant charge of HVRF systems with bBTHX is reduced by 40~70%.en_US
dc.identifierhttps://doi.org/10.13016/M2P26Q52Q
dc.identifier.urihttp://hdl.handle.net/1903/20404
dc.language.isoenen_US
dc.subject.pqcontrolledMechanical engineeringen_US
dc.subject.pquncontrolledbifurcationen_US
dc.subject.pquncontrolledcompacten_US
dc.subject.pquncontrolledfinlessen_US
dc.subject.pquncontrolledheat exchangeren_US
dc.subject.pquncontrolledheat transferen_US
dc.subject.pquncontrollednature-inspireden_US
dc.titleDEVELOPMENT OF A COMPACT HEAT EXCHANGER WITH BIFURCATED BARE TUBESen_US
dc.typeDissertationen_US

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