For copper surfaces:
It was found that with a nanofluids concentration of 0.0001 vol.%, the heat
transfer coefficient increased, compared with base fluid. The heat transfer increased
at an average of 15% with a surface roughness of 0.2 lm and at 4% with a surface
roughness of 4 lm.
On the other hand, with nanofluids’ concentrations of more than 0.0001 vol.%,
the heat transfer coefficient was found to be less than that of the base fluid at
every level of surface roughness.
For aluminium surfaces:
The boiling curve was found to be different from a general boiling curve in that the
excess temperature would vary in accordance with the heat flux only for a certain
amount of time.
After that, it tended to decrease while the heat flux rose. This could be seen from the
experimental with pure water and nanofluid at lower concentrations.
The heat transfer coefficient was found to be less than that of base fluids at every level
of nanofluids concentration and surface roughness.
When comparing copper with aluminium surfaces using
nanofluids and base fluid as experimental substances, it
was found that aluminium surfaces yielded higher heat
transfer coefficients than copper surfaces.
This difference was apparent at high heat flux levels.
When comparing surface roughness of 0.2 lm with 4 lm using
nanofluids and base fluid as experimental substances, it
was found that the surface roughness of 4 lm yielded a
higher heat transfer coefficient than the surface roughness
of 0.2 lm.
This difference could also be seen at high heat flux levels.
Thank you for your attention