In the present study, the rheological behavior of Fe₃O₄-MWCNTs/ethylene glycol hybrid nanofluid was investigated for different volumetric fractions (0.1, 0.25, 0.8, 1.25, and 1.8%) comprising equal amounts of suspended iron oxide (Fe₃O₄) nanoparticles and multi-walled carbon nanotubes (MWCNTs) within the temperature and shear ranges of 25 to 50 °C and 12.24 to 73.44 s⁻¹, respectively. The results indicated that the nanofluid demonstrates a Newtonian behavior at volume fractions of 0.1, 0.25, 0.45, and 0.8%, whereas it demonstrates a non-Newtonian behavior at volume fractions of 1.25 and 1.8% similar to the power law model with an exponent lower than 1. Moreover, it was observed that viscosity is directly proportional to volume fraction, and inversely proportional to temperature. Then, the effect of nanoparticles and nanotubes on the thermal performance of ethylene glycol inside a pipe of heat exchanger was evaluated and the results revealed that an increase in the volume fraction at all temperatures leads to increased pressure drop and heat transfer coefficient. Finally, the results were used to develop an experimental equation as a function of temperature and volume fraction to estimate nanofluid viscosity in the simulations. The predicted values by the equation were in a very good agreement with the experimental results.

在本研究中，研究了Fe ₃ O ₄ -MWCNTs /乙二醇杂化纳米流体的流变行为，该流变行为是针对包含等量悬浮氧化铁（Fe ₃ O ）的不同体积分数（0.1、0.25、0.8、1.25和1.8％）₄）在25至50°C和12.24至73.44 s ^-1的温度和剪切范围内的纳米颗粒和多壁碳纳米管（MWCNT）， 分别。结果表明，纳米流体在体积分数为0.1、0.25、0.45和0.8％时表现出牛顿行为，而在体积分数为1.25和1.8％时表现出非牛顿行为，与幂律模型相似，但指数较低此外，还发现粘度与体积分数成正比，与温度成反比。然后，评估了纳米颗粒和纳米管对热交换器管内乙二醇热性能的影响，结果表明，在所有温度下，体积分数的增加都会导致压降和传热系数的增加。最后，结果被用于建立一个温度和体积分数函数的实验方程，以估算模拟中的纳米流体粘度。该方程的预测值与实验结果非常吻合。