Effect of Freeze Pipe Eccentricity in Selective Artificial Ground Freezing Applications
JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS(2022)
摘要
Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of selective artificial ground freezing (S-AGF) applications for underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of S-AGF systems is analyzed. A 1 + 1D semi-conjugate model that solves two-phase transient energy conservation equation is derived based on the enthalpy method. The 1 + 1D model is first validated against experimental data and then verified with a fully conjugate model from our previous work. After that, the 1 + 1D model is extended to a field-scale of typical underground mines to examine the effect of freeze-pipe eccentricity. The results show that concentric freeze-pipes form the desired frozen ground volume 17% faster than eccentric freeze-pipes. Also, the geometrical profile of the phase-transition front of the frozen ground is found to be significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where S-AGF coolants are isolated from the ground to reduce energy consumption, freeze-pipe eccentricity can increase the coolant heat gain by 20%. This percentage can increase up to 200% if radiation heat transfer is minimized.
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关键词
selective artificial ground freezing,pipe eccentricity,reduced-order model
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