折弯弓形折流板换热器流动换热性能研究

Study on Flow Heat Transfer Performance of Folded Segmental Baffle Heat Exchanger

为了提高折流板换热器的换热性能,改变了折流板换热器的折弯夹角和折流板间距,利用ANSYS Fluent对换热器壳程流体流动与换热过程进行模拟,分析了不同折流板折弯夹角α(110°,135°,170°和180°)、折流板间距(250,300和350 mm)和雷诺数(10000,20000和50000)对换热器壳程压力、速度和温度的影响。结果表明:增大雷诺数对改善流动死区有很大的作用,雷诺数为50000时的流动死区相对于雷诺数为10000时面积减小较大;随着夹角α的减小,折流板背流侧的流动死区面积逐渐减小、换热器的表面传热系数和进出口压降力越大,夹角α为110°时出口温度最小、进出口压降最大,夹角α为135°时PEC最大且换热器综合性能最优;折流板间距增大,压力变化梯度减小,压差变化幅度减小,壳程出口温度变化不成正比关系,间距为300 mm时出口温度最低。

In order to enhance the heat transfer performance of the baffle heat exchanger,the bending angle and the spacing of the baffle heat exchanger were changed,and the fluid flow in the heat exchanger shell and heat transfer process were simulated by using ANSYS Fluent software,and the effects on the pressure,velocity and temperature of the fluid flow in the heat exchanger shell were analyzed under different bending angles of 110°,135°,170°and 180°,baffle spacings of 250,300 and 350 mm and Reynolds numbers of 10000,20000 and 50000.The results show that increasing the Reynolds number has a great effect on improving the dead zone of the flow,and the dead zone of the flow when the Reynolds number is 50000 has a greater area reduction compared with the Reynolds number of 10000;with the decrease of the angle,the dead zone area on the baffle backflow side of the fluid flow is gradually reduced,the greater the heat exchanger surface heat transfer coefficient,the greater the inlet and outlet pressure drop.When the angle is l10°,the outlet temperature is minimum,and the inlet and outlet pressure drops are maximum;when the angle is 135°,the performance evaluation criteria(PEC)is maximum,and the overall performance of the heat exchanger is optimal;the baffle spacing increases,the pressure change gradient decreases,the differential pressure change amplitude decreases,the outlet temperature change in the shell is not proportional to the spacing,and the outlet temperature is the lowest when the spacing is 300 mm.