[har1s]

Dear all,

I am using ANSYS Fluent 14.5 to model simple heat transfer through a flat tube of a radiator. I have modeled a solar plate collector with a fluid running in the tube as well previously. Both the times, I get the same problem which is that when I increase the thermal conductivity of material (fluid) the temperature change decreases. If I am not wrong, if a material has better thermal conductivity, there should be more heat transfer. i.e. It should cool down more along the length of the pipe.
I am looking to compare heat transfer of nanofluids and just base fluids. For example, water compared with water and Al2O3 nanoparticles. With low particle diameter, according to literature, the nanofluid can be considered as one fluid and two-phase modelling is not necessary. The density, specific heat, thermal conductivity and viscosity, all were calculated for the nanofluid and the new values put in the properties section of water in the Fluent database, but I get a lower temperature change always. When I use material with low thermal conductivity, I get a quicker and higher temperature change. Its like the opposite is happening. Help regarding this would be greatly appreciated Thank you.