杈式折流栅对管壳式换热器壳程性能的影响

Effect of branch baffle on shell-side performance of shell-and-tube heat exchanger

杈式折流栅是一种以斜向流和射流混合流动来强化管壳式换热器性能的新型管束支撑结构,用来代替杆式折流栅,可以弥补低雷诺数下,折流杆换热器换热效果的不足,并有效提高传热效率。依据计算流体力学原理和周期性数值模型,研究了杈式折流栅换热器的壳程流体流态、以及结构参数对换热器壳程流动传热的影响,得出了可用于指导工程设计的换热器传热、压降关联式。结果表明:随着折流片定向角及无量纲间距的减小,杈式折流栅换热器的综合性能先增大后减小;同质量流量下,与同尺寸折流杆换热器比较,杈式折流栅换热器的壳程传热系数提升170%-200%,综合性能提高了2.1%-24%,尤其在较低流量下,杈式折流栅的传热效率更加突出。

The branch baffle is a novel tube bundle supporting structure with mixed flow of oblique flow and jet to enhance the performance of shell-and-tube heat exchanger.Instead of the rod baffle,it can make up for the lack of heat transfer effect of rod baffle heat exchanger at low Reynolds number and effectively improve the heat transfer efficiency.According to the principle of computational fluid dynamics and periodic numerical model,the fluid flow pattern of the branch baffle heat exchanger and the influence of structural parameters on the flow and heat transfer in the shell side of the heat exchanger were studied.Heat transfer and pressure drop correlations for the heat exchanger were derived,which can be used to guide the engineering design.The results show that the comprehensive performance of the branch baffle heat exchanger increases at first and then decreases with the decrease of the orientation angle and dimensionless spacing of the baffles;At the same mass flow rate,compared with the same size rod baffle heat exchanger,the shell-side heat transfer coefficient of the branch baffle heat exchanger is increased by 170%-200%,and the comprehensive evaluation index is improved by 2.1%-24.0%,especially at lower flow rates,the heat transfer efficiency of the branch baffle is more outstanding.