三叶孔板换热器壳程传热与压降

三叶孔板换热器是一种新型纵向流换热器，由于其具有传热效率高、压降低、抗振结构性能优越等诸多优点而广泛应用于核电行业。搭建三叶孔板换热器壳程传热与压降测试平台，对传热和压降的测量结果进行不确定度分析。对4台三叶孔板换热器模型进行实验研究，结果表明随着Reynolds数的增大，壳程对流传热系数和压降在对数坐标内线性增大；在Reynolds数相同的情况下，随着支撑板间距的增大，三叶孔板换热器壳程Nusselt数逐渐减小，压降逐渐降低，同时压力梯度逐渐减小。为了进一步分析说明三叶孔板换热器壳程传热与阻力性能，基于Bell-Delaware法设计了具有相同结构参数的折流板换热器。与折流板换热器的对比结果表明：三叶孔板换热器壳程Nusselt数平均为折流板换热器的1.25倍，壳程整体压力平均为折流板换热器的0.77，综合性能平均为折流板换热器的1.62倍。

Shell-side heat transfer and pressure drop of shell-and-tube heat exchanger with trefoil-hole baffles

Shell-and-tube heat exchanger with trefoil-hole baffles (STHX-TH) is a new type of longitudinal-flow heat exchanger which is widely used in nuclear industry due to its higher heat transfer efficiency, lower pressure, superior anti-vibration performance and many other advantages. In order to analyze the thermal-hydraulic performance of STHX-TH, an experimental test platform was established. Then four STHXs-TH with different baffle spaces were tested. The experimental data were reliable and accurate. Heat transfer coefficient and pressure drop decreased linearly with increasing Reynolds number in double logarithmic coordinates. Heat transfer coefficient and pressure drop decreased with increasing baffle space at the same Reynolds number. With the same mass flow, pressure gradient decreased with increasing baffle space. In order to comparatively understand the shell-side heat transfer and pressure drop performance of STHX-TH, a shell-and-tube heat exchanger with segmental baffles (STHX-SB) with similar geometric parameters with STHX-TH (No.2) was designed. Shell-side heat transfer coefficient and pressure drop of STHX-SB were calculated with the Bell-Delaware method, and compared with those of STHX-TH. The comparative study showed that convective heat transfer coefficient of STHX-TH was 1.25 times of that of STHX-SB, pressure drop of STHX-TH was 0.77 time of that of STHX-SB, and Nu_s/Δp_s of STHX-TH was 1.62 times of that of STHX-SB.