不同螺旋折流板换热器壳侧流动的数值研究

Numerical study of shell-side flow of heat exchanger of different helical baffle

采用数值模拟方法,运用大型CFD分析软件Fluent,研究了1/4椭圆螺旋折流板换热器、1/3扇形螺旋折流板换热器以及常见的1/4扇形螺旋折流板换热器壳程流体的流动特点,并与传统的弓形折流板换热器进行对比。采用Gambit软件建立模型和划分网格,采用分离变量法隐式求解,压力和速度耦合采用Simple算法。结果认为,螺旋折流板换热器的传热及阻力性能低于弓形折流板换热器,1/4椭圆螺旋折流板换热器的传热性能及压力损失最小,其次是1/4扇形螺旋折流板换热器,1/3扇形螺旋折流板换热器的壳程传热及阻力性能最高。

This paper investigates the shell-side flow characters in the heat exchangers with the quarter-ellipse, quarter-sector, third-sector helical baffles and the segmental baffles by numerical simulation to find out the factors making the capacity differences among these heat exchangers. The results show that the fluid flow in the heat exchangers with helical baffles approaches a near helical plug flow with no dead space, and the distribution of fluids is more uniform. The angle between the flow direction and the tubes, and the leakage flow in the triangular area make the heat transfer and the flow resistance performances of the heat exchangers with helical baffles are lower than the heat exchanger with segmental baffles. Overlapping between the adjacent helical baffles could restrain the leakage by reducing the size of the triangular area. More overlapping or less amount of the helical baffles in a helix could damage the flow continuity and regularity, so in the three different helical baffles, the third-sector helical baffle offers the highest heat transfer capacity and flow resistance and the quarter-ellipse helical baffle offers the lowest ones.