In recent years, the conventional heat transfer fluid is being replaced by advanced fluid such as nanofluid due to its better heat transfer characteristics and flow characteristics. The application of nanofluids in the thermal management systems brings out not only the better heat transfer and also it reduces the size of the heat exchangers.

The most important exclusivity of hybrid nanofluid refers to composition of two variant types of dispersed nanoparticles in a base fluid. Thus, when materials of particles have been chosen properly, they can enhance the positive features of each other and cover the disadvantages of just one material. According to these features of metallic and nonmetallic nanoparticles, it can be expected that the addition of metal nanoparticles (such as Cu) into a nano-fluid composed based on Al2O3 nanoparticles, can enhance the thermophysical properties of this mixture.

Quiet recently numerous experiments have been done with two types of nanoparticles suspended in base fluid named as “Hybrid Nanofluid”, the cutting edge nanofluid. The principle preferred standpoint of utilizing hybrid nanofluid is by choosing a proper combination of nanoparticles, positive features can be improved and inconveniences can be covered due to their synergistic effect.

Various literature review has revealed that both Al2O3/DI water and CuO/DI water can enhance the thermal performance of heat pipes. However, they have also investigated the role of hybrid nanofluids as potential working fluids in various heat transfer devices because of its high thermal conductivity compared to other fluids.

Al2O3-Cu/water hybrid nanofluid of 0.1% volume concentration can lead to 13.56% enhancement in Nusselt number at Reynolds number of 1730. It has also been accounted that hybrid nanofluids have higher friction factor compared to nanofluid.