Pressure drop and critical mass flux of water flowing upward in a uniformly heated vertical tube

doi:10.16511/j.cnki.qhdxxb.2018.25.039

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Abstract The critical mass flux, G₀, is a key parameter in the design of vertical water wall in once-through boilers. A vertical water wall has positive flow characteristic only when the mass flux inside the parallel tubes is less than G₀. While G₀ has been reported to be 1 000-1 200 kg/(m²·s), there are few studies on the factors influencing G₀ in the literature. This paper presents a hydrodynamic model based on the classical pressure loss computation method and empirical correlations. The model predicts the pressure drop variation for water flowing upward inside a uniformly heated tube at supercritical/subcritical pressures for various heat fluxes, tube lengths and tube inner diameters. The results show that G₀ increases with decreasing heat flux and tube length and decreases with increasing inner diameter.

Keywords vertical water wall low mass flux positive flow characteristic self-compensating characteristic critical mass flux

Issue Date: 21 November 2018

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Cite this article:

TANG Guoli, GU Junping, WU Yuxin, LI Zhouhang, LÜ Junfu, LIU Qing. Pressure drop and critical mass flux of water flowing upward in a uniformly heated vertical tube[J]. Journal of Tsinghua University(Science and Technology),2018, 58(11): 1021-1028.

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http://jst.tsinghuajournals.com/EN/10.16511/j.cnki.qhdxxb.2018.25.039 OR http://jst.tsinghuajournals.com/EN/Y2018/V58/I11/1021

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