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4th Thermal and Fluids Engineering Conference

ISSN: 2379-1748

Numerical Study on the Effect of Cross Section Profile on the Flow and Heat Transfer of Supercritical Water within a Vertically Upward Tube

Shuai Zhao
Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian City, Liaoning Province,, China

Qinggang Qiu
School of Energy and Power Engineering, Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, No.2 Linggong Rd. Ganjingzi District, Dalian City. Liaoning Province 116024, China

Xiaojing Zhu
School of Energy and Power Engineering, Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian City, Liaoning Province,, China

Shengqiang Shen
Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Key Laboratory for Desalination of Liaoning Province, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China

DOI: 10.1615/TFEC2019.cmd.027992
pages 387-396


KEY WORDS: supercritical water, heat transfer, wall temperature distribution, variety of channel type

Abstract

In this paper, heat transfer characteristics of supercritical water in vertical tubes with square cross section, circular cross section and regular triangle cross section, respectively, are studied using ANSYS CFX 14.5 at working conditions of mass flow rate 800 kg/(m2s) , pressure from 23 to 28 MPa and heat flux from 300-1000 kW/m2. The result showed that because of the circumferential heterogeneities of square channels and regular triangle channels, point-to-point simulation from the vertex angle to the midpoint of the edge is a necessary. For square channels and regular triangle channels, the midpoint of the edge has the highest heat transfer coefficient and the vertex angle has the lowest heat transfer coefficient. For the three channels, there is no different between the circular channels and other two channels in the low enthalpy region and the high enthalpy region, but it is obvious that the heat transfer coefficients of circular channels is higher than triangular channels and the square channels in the vicinity of the pseudo-critical point. The reason is that the separation between the boundary layer and the wall surface is likely to occur at the vertex angle, resulting in the reflux of the fluid in the outlet position of computational region and there is a great resistance at the vertex angle, which makes the flow rate of the supercritical water at the vertex angle decreases and reduce the thermal current intensity.

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