Saturated flow boiling heat transfer of R-410A and associated bubble characteristics in a narrow annular duct |
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| Authors: | CA Chen KW Li YM Lie TF Lin |
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| Affiliation: | 1. CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041, PR China;2. Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, 400044, PR China;1. Aix-Marseille University, IUSTI UMR 7343 CNRS, Marseilles, France;2. Southern Methodist University, Department of Mathematics, Dallas, TX 75275, USA;1. School of Mechanical Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 702-701, Republic of Korea;2. Division of Engineering Technology, Oklahoma State University, 563 Engineering North Stillwater, OK 74078, USA;1. State Key Laboratory of Multiphase Flow in Power Engineering, School of Nuclear Science and Technology, Shaanxi Key Lab. of Advanced Nuclear Energy and Technology, Xi''an Jiaotong University, Xi''an, 710049, China;2. Applied Modelling and Computation Group, Department of Earth Science and Engineering, Imperial College London, SW7 2BP, UK |
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| Abstract: | Experiments are conducted here to investigate how the channel size affects the R-410A saturated flow boiling heat transfer and associated bubble characteristics in a horizontal narrow annular duct. The gap of the duct is fixed at 1.0 and 2.0 mm in this study. The measured data indicate that the saturated flow boiling heat transfer coefficient increases with increasing refrigerant mass flux and saturated temperature and with a decrease in the gap size. Besides, raising the imposed heat flux can cause a significant increase in the boiling heat transfer coefficient. The results from the flow visualization show that the mean diameter of the bubbles departing from the heating surface decreases slightly with increasing refrigerant mass flux and saturated temperature. Moreover, the bubble departure frequency increases at reducing duct size and increasing mass flux. And at a high imposed heat flux many bubbles generated from the cavities in the heating surface tend to merge together to form big bubbles. Meanwhile, comparisons of the present heat transfer data for R-410A with R-407C and R-134a in the same duct and with some existing correlations are conducted. Furthermore, an empirical correlation for the present R-410A saturated flow boiling heat transfer data is proposed. |
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