In this paper, an experimental study was carried out in order to investigate the effects of Al₂O₃/water nanofluid with a mean diameter of 50 nm on heat transfer performance in a counter flow double-pipe heat exchanger. The nanofluid was used as cold side fluid and passed through the inner pipe of the double-pipe heat exchanger considering fully developed turbulent flow regime with different Reynolds numbers ranging from 20,000 to 60,000. Experiments were conducted in various cold side fluid flow rates ranging from 1.1 to 3.9 m³/h, inlet temperatures of 40 °C and 50 °C at cold side, and Al₂O₃/water nanofluids of 0.25% and 0.5% nanoparticles volume concentration. Results indicate that the Nusselt number increases with increasing nanoparticles volume concentration and Reynolds number but decreases with the inlet temperature at cold side of double-pipe heat exchanger. The maximum increase of Nu are respectively 23.2% and 32.23% for inlet temperature of 40 °C and 50 °C. In addition, the single-phase model in CFD (Computational Fluid Dynamics) is adopted to simulate the heat transfer performance by ANSYS Fluent commercial software. It is found that the simulated results show a good agreement with the experimental results and results derived from Gnielinski correlation. The maximum error between experimental Nusselt numbers and simulated results are found to be 12.8%. It is concluded that the CFD approach gives good prediction for heat transfer performance in a double-pipe heat exchanger using Al₂O₃/water nanofluids.

本文进行了实验研究，以研究平均直径为50 nm的Al ₂ O ₃ /水纳米流体对逆流双管热交换器中传热性能的影响。考虑到完全发展的湍流状态，不同雷诺数范围为20,000至60,000，纳米流体被用作冷侧流体并通过双管换热器的内管。实验在1.1至3.9 m ³ / h的各种冷侧流体流量，冷侧入口温度为40°C和50°C以及Al ₂ O _{3的情况下进行}/水纳米流体的纳米粒子体积浓度为0.25％和0.5％。结果表明，努塞尔数随着纳米颗粒体积浓度和雷诺数的增加而增加，但随着双管热交换器冷侧入口温度的降低而减小。当入口温度为40°C和50°C时，Nu的最大增加分别为23.2％和32.23％。另外，通过ANSYS Fluent商业软件，采用CFD（计算流体动力学）中的单相模型来模拟传热性能。结果表明，模拟结果与实验结果以及由格涅林斯基相关性得出的结果吻合良好。实验的Nusselt数与模拟结果之间的最大误差为12.8％。₂ O ₃ /水纳米流体。