高温气体穿越液池过程气液传热传质数值分析

Numerical analysis of heat and mass transfer between gas and liquid in process of high temperature gas passing through pool

建立气液二相间动量、热量及质量同时传递数学模型,数值模拟了高温气体穿越液池气液直接接触热质传递规律。模型中考虑了气泡破碎、聚合以及冷却水蒸发等因素的影响。数值模拟获得了液池内气液二相温度变化规律,探讨了液池内表观气速、气泡尺寸以及进入液池气体温度等因素对液池内气液二相温度分布特性的影响。计算结果与实验值吻合较好,验证了模型的可行性。数值模拟结果表明:高温气体在进入液池后,首先经历一个剧烈的气液热质交换过程,存在一个较大的温度梯度变化,而随后气体温度变化趋于平缓;随着液池内表观气速的降低,池内气体温度降低;最大冷却水蒸发速率和最高气体温度均出现在靠近下降管出口的区域。

A theoretical model was used to study the characteristic of heat and mass transfer between gas and liquid in the process of high temperature gas passing through pool under the high temperature and high pressure conditions. In this model,the bubble breakage,coalescence and the evaporation of cooling water were considered.The effects of superficial gas velocity,bubble size,inlet gas temperature and other factors on the temperature distributions of gas and liquid in the pool were studied. The computational results with experimental data were compared. The numerical simulation results show that a larger temperature gradient exists after high temperature gas is injected into pool. With the decreasing of the superficial gas velocity in pool,the gas temperature in the liquid bath decreases. The max. evaporation rate of cooling water and the highest gas temperature in pool all occur in the region near the downcomer outlet.