Gorgy, Evraam I.2008-05-192008-05-192008-05-19http://hdl.handle.net/2097/804This project studied the pool boiling of R-134a and R-123 on smooth and enhanced tubes. This is the 1st phase of ASHRAE project RP-1316 "Experimental Evaluation of The Heat Transfer Impacts of Tube Pitch in a Highly Enhanced Surface Tube Bundle". A Turbo BII-HP and a Turbo BII-LP enhanced tubes were used in this study. These tubes were manufactured and donated by Wolverine Tube, Inc. Four different boiling cases were tested, R-134a on smooth tube, R-123 on smooth tube, R-134a on Turbo BII-HP tube, and R-123 on Turbo BII-LP tube. The first step in this study was performing a modified Wilson plot analysis, once completed, the average and local refrigerant heat transfer coefficients were determined. This thesis also presents the enthalpy-based heat transfer analysis (EBHT), a new method for determining the heat exchanger's overall heat transfer coefficient as a function of the enthalpy change of incompressible fluids. The test tubes' outer diameter is 19.05 mm and length is 1 m. Tests were conducted in a single tube test section, in which the test tube was water heated. All tests were conducted at a saturation temperature of 4.44 °C. The heat flux range is 9.2-126.6 kW/m[superscript]2 for testing with R-134a on smooth tube, 9.2-58 kW/m[superscript]2 for R-123 on smooth tube, 4.1-135.1 kW/m[superscript]2 for R-134a on Turbo BII-HP tube and 4.7-59.8 kW/m[superscript]2 for R-123 on Turbo BII-LP tube. Results show that the heat transfer coefficient increases with heat flux for all cases except the case of R-134a on Turbo BII-HP tube, where it experiences a trend change. Part of this study was comparing the smooth and enhanced tubes performances. R-134a Turbo BII-HP tube to smooth tube heat transfer coefficient ratio changes from 4 at low heat flux to 1.7 at high heat flux. R-123 Turbo BII-LP tube to smooth tube heat transfer coefficient ratio changes from 24 at low heat flux to 7 at high heat flux. The performance of Turbo BII-HP and Turbo BII-LP was found to be very similar over the tested heat flux range of the Turbo BII-LP tube. Comparison plots with available literature are presented.en-US© the author. This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).http://rightsstatements.org/vocab/InC/1.0/Pool BoilingRefrigerantsEBHTEnthalpy-Based Heat Transfer AnalysisThesisEngineering, Mechanical (0548)