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应用CFD软件研究了安装在反应釜内壁侧的螺旋半圆管夹套内流体的湍流换热特性,分析了雷诺数Re和曲率δ对换热特性的影响,并以熵产数为指标对夹套换热性能进行了基于热力学第二定律的分析评价.结果表明,弯曲换热壁面两侧主二次涡涡心附近无量纲温度最小,而壁面中心点附近最大,是换热最差的部位.同一δ下,Re增加使二次涡强度和流体湍动能增大,夹套换热综合性能系数Nu_m/f增大;同一Re下,δ增加使二次涡强度增大而流体湍动能减小,Nu_m/f值减小.研究范围内,釜内夹套换热壁面的平均努塞尔数Nu_m为釜外夹套的1.168~1.241倍,摩擦阻力系数f为其1.021~1.077倍.结构确定的夹套存在一个最佳平均雷诺数(Re_(op))使换热过程的不可逆损失最小,随δ增加,RP_(op)逐渐增大.半圆截面2个尖角附近是夹套内有用能损失的主要部位.
The effects of Reynolds number Re and curvature δ on the heat transfer characteristics were analyzed by using CFD software. The effects of Reynolds number Reynolds number on the heat transfer characteristics of the jacket were studied. The results show that the dimensionless temperature near the center of the second eddy in both sides of the curved heat exchange wall is the smallest, while the maximum near the center of the wall is the worst part of the heat exchange. Under the same δ, the increase of Re leads to the increase of secondary vortex intensity and fluid turbulence kinetic energy, and the overall performance coefficient of jacket heat transfer, Nu_m / f, increases. Under the same Re, the increase of δ increases the secondary vortex intensity and the fluid turbulent kinetic energy decreases , And the value of Nu_m / f decreased.Under the research scope, the average Nusselt Nu_m of the heat exchange wall in the kettle was 1.168-1.241 times of the outer jacket of the kettle, and the coefficient of frictional resistance f was 1.021-1.077 times. (Re_ (op)) has the least irreversible loss in the heat transfer process and RP_ (op) gradually increases with the increase of δ. The two sharp corners near the semicircular section are useful energy in the jacket The main part of the loss.