Analysis of stagnant non condensable gases effects on condensation heat transfer in a vertical tube
In a vertical condenser tube installed at the cold end of a non-vacuum separate type heat pipe, non condensable (NC) gases in the system is pushed by continuous vapor flowing from the hot end into the condenser tube at the cold end, gathering above condensate at the outlet of the condenser tube. Therefore, condensation heat transfer of vapor with the stagnant NC gases occurs in the condenser tube. It is necessary to comprehend the effects of stagnant NC gases on condensation heat transfer. A VOF method was adopted to analyze how stagnant NC gases affect condensation heat transfer, a mass fraction equation of NC gases was used to solve diffusion between NC gases and vapor, a Hertz-Knudsen-Schrage model was applied to deal with condensation rate of vapor on the surface of liquid film. Parameters, including volume fraction, velocity, pressure, mass fraction of NC gases and condensation heat transfer coefficients (HTC), were obtained. Results show that a lot of NC gases deposits in the condenser tube rear, leading a lot of vapor to condense at the condenser tube front. NC gases slightly affect condensation HTC of the tube front, and severely degrade condensation HTC of the tube rear. Furthermore, an increase in mass of NC gases causes a rise in pressure and velocity, improving condensation heat transfer.
Condensation Heat transfer Non-condensable gases
Junxia Zhang Zengsheng Li Binyao Gong Hongxing Zhao Yuhuai Zhao
School of Energy and Engineering, Yulin University, Yulin, Shanxi Province 719000, China Department of Mathematics, Yulin University, Yulin, Shanxi Province 719000, China
国际会议
大连
英文
491-495
2011-10-19（万方平台首次上网日期，不代表论文的发表时间）