Refrigerant flow boiling heat transfer in parallel microchannels as a function of local vapor quality |
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| Authors: | Stefan S Bertsch Eckhard A Groll Suresh V Garimella |
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| Affiliation: | 1. Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907-2088, USA;2. Cooling Technologies Research Center, School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907-2088, USA;1. Boiling and Two-Phase Flow Laboratory (BTPFL), School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907, USA;2. NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135, USA;1. College of Engineering, Design and Physical Science, Brunel University of London, Uxbridge, London, UK;2. Heat Transfer Research Group, Escola de Engenharia de São Carlos (EESC), University of São Paulo (USP), São Carlos, SP, Brazil;1. Department of Mechanical & Electrical Engineering, Xiamen University, Xiamen 361005, China;2. ShenZhen Research Institute of Xiamen University, ShenZhen 518057, China;3. ABB Xiamen Low Voltage Equipment Company, 12-20 Chuangxin 3rd Road, Xiamen 361006, China;4. Key Laboratory of Surface Functional Structure Manufacturing of Guangdong High Education Institutes, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China |
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| Abstract: | Flow boiling of refrigerant HFC-134a in a multi-microchannel copper cold plate evaporator is investigated. The heat transfer coefficient is measured locally for the entire range of vapor qualities starting from subcooled liquid to superheated vapor. The test piece contains 17 parallel, rectangular microchannels (0.762 mm wide) of hydraulic diameter 1.09 mm and aspect ratio 2.5. The design of the test facility is validated by a robust energy balance as well as a comparison of single-phase heat transfer coefficients with results from the literature. Results are presented for four different mass fluxes of 20.3, 40.5, 60.8, and 81.0 kg m?2 s?1, which correspond to refrigerant mass flow rates of 0.5–2.0 g s?1, and at three different pressures 400, 550 and 750 kPa corresponding to saturation temperatures of 8.9, 18.7, and 29 °C. The wall heat flux varies from 0 to 20 W/cm2 in the experiments. The heat transfer coefficient is found to vary significantly with refrigerant inlet quality and mass flow rate, but only slightly with saturation pressure for the range of values investigated. The peak heat transfer coefficient is observed for a vapor quality of approximately 20%. |
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