The present study aims to research the thermohydraulic characteristics and performance index for flow of the nanofluids containing varied particle shapes including cylinder, blade, brick, platelet, and Oblate Spheroid (OS) in a shell and tube heat exchanger (STHX). The STHX is equipped with new unilateral ladder-type helical baffles to develop spiral stream inside the shell side. The nanofluid is assumed as the hot fluid that passes inside the tube side. Water is selected for the cold fluid that flows within the shell side with Reynolds numbers of 5000 to 20,000. The flow pattern developed by the baffles has noticeable impacts on the STHX performance. By the rise in the Reynolds number of the shell side, the heat transfer rate, overall heat transfer coefficient, effectiveness, Number of Transfer Unit (NTU), and pressure drop increase, whereas the performance index decreases. Moreover, the highest heat transfer rate, overall coefficient, and pressure loss belong to the nanofluid containing the platelet additives, while the greatest effectiveness, NTU, and performance index happen for the nanofluid with the OS additives. The severe cross and secondary flows are completely obvious in the shell side due to the existence of the new baffles, specially at high Reynolds numbers.

本研究旨在研究壳管式热交换器（STHX）中包含圆柱，刀片，砖块，血小板和扁球形（OS）在内的各种颗粒形状的纳米流体的流动的热工液压特性和性能指标。STHX配备了新的单侧梯形螺旋形挡板，可在壳侧形成螺旋流。纳米流体被认为是在管内通过的热流体。选择水作为流向壳侧的雷诺数为5000至20,000的冷流体。挡板形成的流动模式对STHX性能产生明显影响。随着壳侧雷诺数的增加，传热速率，总传热系数，效率，传递单位数（NTU）和压降增加，而性能指标下降。此外，最高的传热速率，总系数和压力损失属于包含血小板添加剂的纳米流体，而具有OS添加剂的纳米流体的有效性，NTU和性能指标最大。由于存在新的折流板，特别是在高雷诺数时，在壳侧出现了严重的横流和二次流，这是完全显而易见的。