半圆柱空间异形孔板换热器热工水力性能的数值模拟

为研究半圆柱空间异形孔板换热器的流动与传热特性,建立换热器简化物理模型,运用ANSYS软件建立CFD模型进行数值模拟,分析了开孔形状与板间距的影响,并对比了半圆柱空间异形孔板换热器与弓形板换热器的联系与区别。研究结果表明：半圆柱异形孔板换热器壳侧流体呈纵向流动,壳侧流体通过孔隙形成射流冲刷管壁,具有强化传热作用;板间距一定,开孔面积相近时,开孔形状对壳侧压降的影响较小,对换热性能的影响稍大;板间距越小壳侧换热系数越高但其综合性能指标越小;圆头三角孔板换热器在板间距30 mm时的壳侧换热系数比40及50 mm方案分别高5.62%,10.06%,综合性能指标低1.44%,2.07%;异形孔板换热器的综合性能指标比弓形折流板换热器平均约高27.89%。

Numerical Simulation of Thermal and Hydraulic Performance of Heat Exchanger with Orifice Baffles in Half Cylindrical Space

To study the flow and heat transfer characteristics of the heat exchanger with orifice baffles in half cylindrical space,a simplified physical model of heat exchanger was established.The ANSYS software was adopted to establish CFD model and conduct simulation analysis.The influences of orifice shape and baffle pitch as well as the correlation and difference between the heat exchangers with orifice and segmental baffles in half cylindrical space were compared.The results show that the shell side flow pattern of the heat exchanger with orifice baffles in half cylindrical space is mainly longitudinal,and the tube bundle is swept by jet flow formed through the gaps between baffle orifices and tubes which enhances heat transfer.The influence of the orifice shape on the heat transfer performance is more obvious than on the shell side pressure drop with same baffle pitch and similar orifice area.It is also revealed that the smaller the baffle pitch is,the higher the shell side heat transfer coefficient is,but the smaller the comprehensive performance index is.As for the fillet triangular baffles scheme,the shell side heat transfer coefficient of the scheme of 30 mm baffle pitch is 5.62% and 10.06% higher and the comprehensive performance index is 1.44% and 2.07% lower than those of the schemes of 40 mm and 50 mm respectively.Furthermore,the comprehensive performance index of the heat exchanger with orifice baffles is about 27.89% higher than that of the segmental one averagely.