CNT nanofluid is getting attention in heat transfer applications due to its high thermal conductivity in comparison with conventional fluids. Effective dispersion of CNT in a polar base fluid is a challenging task because CNT is hydrophobic. Researchers used surfactants to overcome this problem but the addition of surfactants has some disadvantages like foaming, stickiness and an increase in viscosity, which increases pumping power required to pump the nanofluid. Alternate methods to prepare efficient nanofluid have to be found. This led to the synthesis of hybrid nanofluid. In this paper, Cu–CNT hybrid nanoparticles have been synthesized by in situ synthesis of Cu nanoparticles in the presence of CNT nanoparticles and dispersed in double-distilled water without surfactant to get stable nanofluid. FESEM with EDX and Raman spectroscopy were used to characterize surface morphology of Cu–CNT hybrid nanoparticles and it was found that copper nanoparticles were present on the outer surface of MWCNT. The dispersibility of Cu–CNT hybrid nanofluid was investigated by spectral analysis method, Zeta potential and DLS. The results revealed that samples were highly stable and the maximum stability was found to be more than 170 days. Nanofluid showed a negligible increase in density and viscosity and showed an enhancement in thermal conductivity compared to base fluid which is essential for heat transfer applications.

由于CNT纳米流体与传统流体相比具有很高的导热性，因此在传热应用中受到关注。CNT在极性基础液中的有效分散是一项艰巨的任务，因为CNT是疏水的。研究人员使用表面活性剂解决了这个问题，但是添加表面活性剂存在一些缺点，例如起泡，粘性和粘度增加，这增加了泵送纳米流体所需的泵送功率。必须找到制备有效纳米流体的替代方法。这导致了混合纳米流体的合成。在本文中，通过在CNT纳米粒子存在下原位合成Cu纳米粒子，并在没有表面活性剂的情况下将其分散在双蒸馏水中得到稳定的纳米流体，从而合成了Cu-CNT杂化纳米粒子。用具有EDX的FESEM和拉曼光谱法表征了Cu-CNT杂化纳米颗粒的表面形态，发现MWCNT外表面存在铜纳米颗粒。通过光谱分析，Zeta电位和DLS研究了Cu-CNT杂化纳米流体的分散性。结果表明，样品是高度稳定的，发现最大稳定性超过170天。与对于传热应用必不可少的基础流体相比，纳米流体在密度和粘度方面的增加可忽略不计，并且在导热性方面也有所提高。通过光谱分析，Zeta电位和DLS研究了Cu-CNT杂化纳米流体的分散性。结果表明，样品是高度稳定的，发现最大稳定性超过170天。与基础流体相比，纳米流体的密度和粘度增加可忽略不计，并且导热性增强，而基础流体是传热应用必不可少的。通过光谱分析，Zeta电位和DLS研究了Cu-CNT杂化纳米流体的分散性。结果表明，样品是高度稳定的，发现最大稳定性超过170天。与对于传热应用必不可少的基础流体相比，纳米流体在密度和粘度方面的增加可忽略不计，并且在导热性方面也有所提高。