1), because every metal has different  heat capacity depending on the surface area of the particle, some metals have good or bad heat dissipation   and depending on this can alter the fluid viscosity, a metal more capable of dissipating the heat could make the particles of the fluid stick together at higher temperatures  with the same viscosity and vise versa. 

because, there are many parameters effecting the thermal conductivity enhancement?

Article Measuring and ANFIS Modelling for Thermal Conductivity of Cu...

Dear Zeeshan Ahmed

First important thing is application of nanofluids. Where we want to use the nanofluids? If the application need the fluids then to enhance the efficiency of that system, nanoparticles will dispersed in the base fluid so that fluid thermal conductivity enhanced appreciably.

Our aim is to enhance the thermal conductivity if fluid which was using in any thermal applications.

Moreover, the nanofluids thermophysical properties such as thermal conductivity, viscosity, density and specific heat have to determined and verify with the existing results before proceeding for any experiments.

Hope you can understand.

Dear Z. Ahmed,

The prime importance of any nanofluid, is to either enhance the heat transfer, depending on its role or applications. For eg., It depends on being used as a nanorefrigerant within the evaporator to absorb more heat from the source to be cooled or it is used as a nanocoolant inside radiators of heavy vehicles or battle tanks.

However there is a need for enhancement in thermal conductivity with lesser viscosity and I could only infer from the study that amorphous materials will have lesser heat transfer ability compared to that of crystalline substances, but the former has lesser viscosity. compared to the latter and hope so you know why is it so.

So it is not only about enhancing the heat transfer by merely saying that a metal nanoparticle enhances thermal conductivity, but the study involves around the nanolayer formation that could contribute lesser viscosity to have lesser pressure drop, hence lesser pumping power to circulate the fluid through any thermal system.

I expect that your inquisitive thirst is quenched.

Expecting a viable reverting for stronger brainstorming.

Thank you.

Dear Sir,

Hope that this paper helps you.

https://www.researchgate.net/publication/319445996_Enhancement_Heat_Transfer_of_Cu-Water_Nanofluids_with_Thermophysical_Properties_Modeling_by_Artificial_Neural_Network

Good luck

You will need ultrasonic vibrator to mix the required nano particles with the fuel, and you can scan a sample of the mixture to show if it homogeneous solution or no. Also, with naked eyes, You can observe the time through which settlement occurs.

for number of samples required, this depends on your operating conditions range, and I prefer that you use dilute solution (φ