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Abstract
In the present work, air-water two-phase flow pattern and pressure drop in vertical upward annular channel with different diameters are experimentally studied. Two concentric annular test sections with the same hydraulic diameter of 4.6 mm are used in the experiments. The outer diameter and inner diameter corresponding to the two test sections are 18.60 and 12.30, and 86.75 and 80.45, respectively. Bubble flow, cap-slug flow, cap-churn flow, and annular flow were found in both the test sections and the flow pattern map is developed. It is found that the superficial gas velocity has an important effect on the transition of the flow patterns. Pressure drop correlations are reviewed and a total of 12 correlations are collected, including 4 homogeneous flow model (HFM)-based correlations and 8 separated flow model-based correlations. The existing correlations for estimating pressure drop were tested against the measured data. The comparisons show that no correlation studied here provides satisfactory agreement with the whole database. The Chisholm correlation provides the best accuracy with 20.9% for the small test section and 21.5% for large test section. It is also found that the existing models based on separated flow method predict frictional pressure drop with higher accuracy than those based on HFM. The result of this study highlights the requirement of a new method for calculating the frictional pressure drop in annular channels.
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Notes on contributors
Nailiang Li
Nailiang Li obtained his PhD degree in power engineering and engineering thermophysics at the State Key Laboratory of Multiphase Flow at Xi’an Jiaotong University, Xi’an, China. His current research focuses on flow assurance of subsea pipelines. He is experienced at experiments and modeling of multiphase flow in complex pipelines. He has published over 10 journal papers.
Changsong Liu
Changshong Liu is a junior undergraduate in School of Low-carbon Energy and Power Engineering, China University of Mining and Technology, Xuzhou, Jiangsu, China. He hosted the National College Student Innovation and Entrepreneurship Training Program project and won the first prize in the Chinese College Student Mechanical Engineering Innovation and Creativity Competition.
Xurui Peng
Xurui Peng is a postgraduate in School of Low-carbon Energy and Power Engineering China University of Mining and Technology, Xuzhou, Jiangsu, China. He received his bachelor’s degree in 2022 from Nanjing Tech University, Nanjing, Jiangsu, China. He is mainly engaged in research on multiphase flow.
Xueping Du
Xueping Du is an Associate Professor in School of Low-carbon Energy and Power Engineering, China University of Mining and Technology. He received his PhD degree in power engineering and engineering thermophysics from Xi’an Jiaotong University. His main research interests are multiphase flow and heat transfer, novel heat exchangers, numerical heat transfer, waste heat utilization, natural gas liquefaction, cold energy utilization, thermal analysis, thermal management, and the application of artificial intelligence in thermal engineering. He has published more than 60 papers in international journals or conferences. He is also a reviewer for several journals.