反应釜内螺旋半圆管夹套内流体的湍流换热性能及熵产分析  

Analyses on Turbulent Heat Transfer Performance and Entropy Generation of Fluid in the Inner Half Coiled Jacket

作　　者：李雅侠[1] 董国先[1] 吴剑华[1] 张先珍[1] 

机构地区：[1]沈阳化工大学能源与动力工程学院,辽宁沈阳110142

出　　处：《过程工程学报》2013年第4期555-561,共7页The Chinese Journal of Process Engineering

基　　金：中央支持地方高校发展专项基金资助项目(编号:2050205)

摘　　要：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.Fluid turbulent heat transfer in the inner half coiled jacket is numerically studied by using CFD software Fluent with the focus on the effects of Reynolds number Re and curvature ratio 8 on heat transfer characteristics. Jacket heat transfer is evaluated by entropy generation number based on the second law of thermodynamics. The results show that minimum dimensionless temperatures of the heated curved wall are near the two main primary secondary flow vortices. The maximum value is at the centre of the heated wall, where is the worst position for heat transfer. At the same 8value, the secondary flow intensity and turbulent kinetic energy are both enhanced with the increase of Re, which promotes the comprehensive performance coefficient Num/f of jacket. At the same Re value, the increase of 8makes the secondary flow intensity enhance but turbulent kinetic energy abate, which reduces Num/fvalue. Average Nusselt number of the heated wall Nun, for the inner half coiled jacket is 1.168~1.241 times and friction coefficientf 1.021~1.077 times of that for the outer half coiled jacket in the studied scope. There is an optimal Reynolds number Reop making the irreversible loss least in the inner half coiled jacket. Reop is enhanced with the increase of δ. The important positions of useful energy loss in the inner half coiled jacket are near the two dead zones of semicircular cross section.

关 键 词：釜内螺旋半圆管夹套 湍流换热 熵产 数值模拟 

分 类 号：TK124[动力工程及工程热物理—工程热物理]