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Abstract
Printed circuit heat exchanger has been recognized as a perspective mini-channel heat exchanger. Semi-circular cross-section is designed here due to the special manufacture technology. However, there is a lack of related investigations on condensation process in mini-channels with semi-circular cross-section. In this paper, corresponding three-dimensional numerical simulations are presented. The horizontal straight channels with radius of 1 mm and 1.222 mm, and length of 250 mm are considered as the geometric models. Constant mass flux (317 kg/m2 s) and wall temperature (310 K) are applied as the boundary conditions. Heat transfer and flow characteristics are conducted by comparing to that in common circular channel with identical wetted perimeter. The effect of placing direction and surface wettability are present as well. The results show that the liquid film in the semi-circular channel is more uneven compared to that in the circular channel. The liquid is accumulated in corners because of surface tension, and this brings worse heat transfer to the semi-circular channel further. Besides, the placing direction has little influence on heat transfer with the variation range of heat transfer coefficient within 4% in the present conditions. The influence of surface wettability can be neglected for the larger tube.
Acknowledgment
The support from the National Key R&D Program of China (2018YFB1501003) is gratefully acknowledged.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Zhao-Rui Peng
Zhao-Rui Peng is a Ph.D. candidate in Department of Energy and Resources Engineering, College of Engineering at Peking University, Beijing, China. His current research include heat transfer and fluid flow of near-critical flows, heat transfer and flow of granular flow, compact heat exchangers, and new thermodynamic cycles.
Qiu-Yun Zheng
Qiu-Yun Zheng is an associate research fellow in Department of Energy and Resources Engineering, College of Engineering at Peking University, Beijing, China. He obtained his Ph.D. in Mathematics in 2010. His main research fields include heat and mass transfer of supercritical-critical flows, compact and efficient heat exchangers, heat pump and refrigeration of natural working fluids, and theories, simulations and applications in the storage, transportation, processing processes of agricultural products.
Xin-Rong Zhang
Xin-Rong Zhang is a professor in Department of Energy and Resources Engineering, College of Engineering at Peking University, Beijing, China. He obtained his Ph.D. in Engineering Thermophysics in 2002 from Tsinghua University. His research interests include supercritical and near-critical flows, renewable thermal energy and new thermodynamic cycles, multi-scale flow and heat transfer simulation and optimization. He has authored about 150 peer-reviewed journal papers and was awarded “Most Cited Chinese Researchers” by Elsevier from 2015 to 2019.