超临界二氧化碳管道T型三通数值计算分析

Numerical Study on T-junction of Supercritical carbon dioxide Pipeline

超临界二氧化碳发电系统厚壁管道件存在非等温流体混合。为降低管道连接区域温差应力影响,本文以某台超临界二氧化碳锅炉内部管道含内套管T型三通为研究对象,运用k-ε方程进行流场计算并与管壁传热进行耦合。计算结果表明:在薄弱的管件相贯线处,不同工况下温度梯度变化均出现相同变化,即最高点出现在三通相贯线后缘,次高点出现在相贯线前缘;温差是相贯线处温度梯度的决定因素,温度梯度基本与温差成正比;相贯线处最大温度梯度随速度比呈先增大后降低趋势,但影响幅度较小。

Mixing of non-isothermal streams occurs in the pipeline, which is an important component part of supercritical carbon dioxide generation power system. In this paper, to weaken the thermal stress of T-junction area in the pipeline, a T-junction with thermal sleeve located in a supercritical carbon dioxide boiler, is investigated. k-ε equation is used for flow calculation coupled with pipe wall heat transfer. The study results show: At the weak pipe intersecting line,temperature gradient gives similar change trend in different conditions,that is peak value at the trail-edge while second peak at the leading-edge;temperature gradient is directly in proportional to temperature difference, which is determinant;While velocity ratio increasing,temperature gradient climbs up first and then declines in low amplitude.