Effect of fin thickness on the air-side performance of wavy fin-and-tube heat exchangers under dehumidifying conditions |
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| Affiliation: | 1. Department of Mechanical Engineering, Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), King Mongkut’s University of Technology Thonburi, Bangmod, Bangkok 10140, Thailand;2. Energy and Resources Laboratory, Industrial Technology Research Institute, Hsinchu 310, Taiwan, ROC;1. Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240, China;2. Daikin Industries, Ltd., 1-1 Nishi Hitotsuya, Settsu-shi, Osaka 566-8585, Japan;1. High Speed Reacting Flow Laboratory, Department of Thermofluids, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai 81310, Johor, Malaysia;2. Department of Energy Engineering, Technical College of Engineering, Duhok Polytechnic University (DPU), 61 Zakho Road, 1006 Mazi Qr, Duhok-Kurdistan Region, Iraq;1. Key Laboratory of Thermo-Fluid Science and Engineering, MOE, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China;2. Department of Energy Sciences, Faculty of Engineering, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden;1. School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China;2. Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy & Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China |
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| Abstract: | This study investigated the effect of fin thickness on the air-side performance of wavy fin-and-tube heat exchangers under dehumidifying conditions. A total of 10 samples were tested with associated fin thickness (δf) of 0.115 mm and 0.25 mm, respectively. For a heat exchanger with two rows (N = 2) and fin pitch Fp of 1.41 mm, the effect of fin thickness on the heat transfer coefficient is more pronounced. The heat transfer coefficients for δf = 0.25 mm is about 5–50% higher than those for δf = 0.115 mm whereas the pressure drop for δf = 0.25 mm is about 5–20% higher. The unexpected difference in heat transfer coefficient subject to fin thickness is attributable to better interactions between the directed main flow and the swirled flow caused by the condensate droplet for δf = 0.25 mm. The maximum difference in heat transfer coefficients for N = 2 and Fp = 2.54 mm subject to the influence of fin thickness is reduced to about 20%, and there is no difference in heat transfer coefficient when the frontal velocity is above 3 m/s. For N ⩾ 4 and Fp = 2.54 mm, the influence of fin thickness on the heat transfer coefficients diminishes considerably. This is because of the presence of tube row, and the unsteady/vortex shedding feature at the down stream of wavy channel. Based on the present test results, a correlation is proposed to describe the air-side performance for wavy fin configurations, the mean deviations of the proposed heat transfer and friction correlations are 7.9% and 7.7%, respectively. |
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