The objective of the present work is to evaluate the experimental convective heat transfer coefficient and friction factor of the nanofluids flowing through a copper tube under a uniform heat flux of 7962 W/m². Water-based stable fly ash and fly ash– Cu (80:20% by vol.) hybrid nanofluids were used as working fluids in the concentration range of 0.5 to 2.0 vol%. Experiments in the Reynolds number range of 6800 to 45,200 were performed at fluid inlet temperatures in the temperature range of 30 to 60 °C. The findings suggest that compared to water and fly ash nanofluid, thermal conductivity, viscosity, and the heat transfer rate of hybrid nanofluid is higher. At fluid inlet temperature of 60 °C, the maximum Nusselt number augmentation for fly ash-Cu hybrid nanofluid is 15.6% and 93.5% was observed at a concentration of 2.0% compared to fly ash nanofluid and water, respectively. A maximum thermal performance factor of 1.65 and 1.87 is observed for fly ash and hybrid nanofluid respectively at 60 °C with a 2.0% volume concentration. Correlations for evaluating the Nusselt number and friction factor of hybrid nanofluid were developed with the experimental data.

本工作的目的是评估在均匀热通量7962 W / m ²下流过铜管的纳米流体的实验对流传热系数和摩擦系数。。水性稳定的粉煤灰和粉煤灰-Cu（体积比为80：20％）杂化纳米流体被用作工作流体，其浓度范围为0.5％至2.0％（体积）。在流体入口温度为30至60°C的温度下进行了雷诺数为6800至45,200的实验。研究结果表明，与水和粉煤灰纳米流体相比，杂化纳米流体的热导率，粘度和传热率更高。在流体入口温度为60°C时，与粉煤灰纳米流体和水相比，粉煤灰-铜杂化纳米流体的最大Nusselt数增加分别为15.6％和93.5％（浓度为2.0％）。粉煤灰和杂化纳米流体分别在60°C和2.0％的体积浓度下观察到最大热性能因子1.65和1.87。