Both mono and hybrid nanofluids, the engineered colloidal mixture made of the base fluid and nanoparticles, have shown many interesting properties and become a high potential nextgeneration heat transfer fluids in various heat exchangers for engineering applications. The present review focuses on improving the performance of tubular heat exchangers by using nanofluids. For this, the present review briefly summarizes the preparation, characterization and thermophysical properties (thermal conductivity, viscosity, specific heat capacity and density) of mono and hybrid nanofluids. Research works on heat transfer and pressure drop characteristics of nanofluids in the double tube and shell-tube heat exchangers with both straight and coiled tubes, and various engineering applications (power generation, refrigeration and air-conditioning, renewable energy, domestic cooling or heating, etc.) are well-grouped and thoroughly discussed. Physical mechanisms for the heat transfer enhancement using nanofluids are explored as well. Most of the studies reveal that there are significant enhancements in the heat transfer process and in the effectiveness of both straight and coiled tube heat exchangers with a slight increase in pressure drop using nanofluids. Hence, there is an excellent opportunity to use nanofluids in tubular heat exchangers; however, high cost (high payback period) and stability are the main challenges for practical implementation. Finally, some useful recommendations are also provided.

由基础流体和纳米颗粒制成的工程胶体混合物，单纳米流体和混合纳米流体都显示出许多有趣的特性，并在各种热交换器中成为工程应用中的高潜力下一代传热流体。本综述着重于通过使用纳米流体来改善管状热交换器的性能。为此，本综述简要总结了单纳米流体和杂化纳米流体的制备，表征和热物理性质（导热系数，粘度，比热容和密度）。有关具有直管和盘管的双管和壳管式热交换器中纳米流体的传热和压降特性的研究工作，以及各种工程应用（发电，制冷和空调，可再生能源，家用制冷或供暖等）进行了分组并进行了全面讨论。还探索了使用纳米流体增强传热的物理机制。大多数研究表明，使用纳米流体的压降略有​​增加，在传热过程和直管式和盘管式换热器的有效性方面都有显着提高。因此，存在在管状换热器中使用纳米流体的绝佳机会。但是，高成本（高投资回收期）和稳定性是实际实施的主要挑战。最后，还提供了一些有用的建议。大多数研究表明，使用纳米流体的压降略有​​增加，在传热过程和直管式和盘管式换热器的有效性方面都有显着提高。因此，存在在管状换热器中使用纳米流体的绝佳机会。但是，高成本（高投资回收期）和稳定性是实际实施的主要挑战。最后，还提供了一些有用的建议。大多数研究表明，使用纳米流体的压降略有​​增加，在传热过程和直管式和盘管式换热器的有效性方面都有显着提高。因此，存在在管状换热器中使用纳米流体的绝佳机会。但是，高成本（高投资回收期）和稳定性是实际实施的主要挑战。最后，还提供了一些有用的建议。高成本（高投资回收期）和稳定性是实际实施的主要挑战。最后，还提供了一些有用的建议。高成本（高投资回收期）和稳定性是实际实施的主要挑战。最后，还提供了一些有用的建议。