Experimental study of horizontal flattened tubes performance on condensation of R600a vapor |
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| Affiliation: | 1. Center of Excellance in Design and Optimization of Energy Systems, School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran;2. Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA;1. Heat and Thermodynamics Division, Department of Mechanical Engineering, Faculty of Mechanical Engineering, Yildiz Technical University, Yildiz, Besiktas, Istanbul 34349, Turkey;2. Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab. (FUTURE), Department of Mechanical Engineering, Faculty of Engineering, King Mongkut''s University of Technology Thonburi, Bangmod, Bangkok 10140, Thailand;1. Department of Mechanical and Electrical Engineering, Qingdao University of Science and Technology, 99 Songling Road, Qingdao 266061, China;2. Department of Energy Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China;3. State University of New York College at Buffalo, 1300 Elmwood Avenue, Buffalo, NY 14222, USA;4. Institut für Thermodynamik, Leibniz Universität Hannover, An der Universität 1, Garbsen 30823, Germany |
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| Abstract: | An empirical setup has been established to study heat transfer and pressure drop characteristics during condensation of R600a, a hydrocarbon refrigerant, in a horizontal plain tube and different flattened channels. Round copper tubes of 8.7 mm I.D. were deformed into flattened channels with different interior heights of 6.7 mm, 5.2 mm and 3.1 mm as test sections. The test conditions include heat flux of 17 kw/m2, mass velocity in the range of 154.8–265.4 kg/m2s and vapor quality variation from approximately 10% to 80%. Results indicate that flattening the tubes causes significant enhancement of heat transfer coefficient which is also accompanied by simultaneous augmentation in flow pressure drop. Therefore, the overall performance of the flattened tubes with respect to heat transfer enhancement considering the pressure drop penalty is analyzed. It is concluded that the flattened tube with 5.2 mm inner height tube has the best overall performance. Due to the failure of pre-existing correlations for round tube condensation heat transfer, a new correlation is proposed which predicts 90% of the entire data within ± 17% error. |
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