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›› 2013, Vol. 13 ›› Issue (4): 555-561.

• 流动与传递 • 上一篇    下一篇

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

李雅侠 董国先 吴剑华 张先珍   

  1. 沈阳化工大学能源与动力工程学院 沈阳化工大学能源与动力工程学院 沈阳化工大学能源与动力工程学院 沈阳化工大学能源与动力工程学院
  • 收稿日期:2013-04-16 修回日期:2013-06-14 出版日期:2013-08-20 发布日期:2013-08-20
  • 通讯作者: 李雅侠

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

LI Ya-xia DONG Guo-xian WU Jian-hua ZHANg Xian-zhen   

  1. Shenyang Institute of Chemical Technology Shenyang Institute of Chemical Technology College of Mechanical Engineering, Shenyang Institute of Chemical Technology College of Mechanical Engineering, Shenyang Institute of Chemical Technology
  • Received:2013-04-16 Revised:2013-06-14 Online:2013-08-20 Published:2013-08-20
  • Contact: LI Ya-xia

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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d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d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Num/f增大；同一Re下，d增加使二次涡强度增大而流体湍动能减小，Num/f值减小. 研究范围内，釜内夹套换热壁面的平均努塞尔数Num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(Reop)使换热过程的不可逆损失最小，随d增加，Reop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.

关键词: 釜内螺旋半圆管夹套, 湍流换热, 熵产, 数值模拟

Abstract: 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 d 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 d value, 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 d makes the secondary flow intensity enhance but turbulent kinetic energy abate, which reduces Num/f value. Average Nusselt number of the heated wall Num for the inner half coiled jacket is 1.168~1.241 times and friction coefficient f 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 d. The important positions of useful energy loss in the inner half coiled jacket are near the two dead zones of semicircular cross section.

Key words: inner half coiled jacket, turbulent heat transfer, entropy generation, numerical simulation

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