Nanofluid technology is becoming an innovative challenge for heat transfer fluids due to considerable enhancement in thermal conductivity of nanofluids at lower nanopartical volume fraction. Nanofluid is a two phase mixture which is made up of suspension of nano-size particles into base fluid (water, ethylene glycol, engine oil), in order to enhance the heat transfer property of base fluids. Choi reported the enhancement in thermal conductivity of base fluid by dispersion of metallic or non metallic nano-size particles. After Choi many researchers have reported their theoretical, experimental and numerical, results on the thermo-physical properties of nanofluids. In the literature several researchers reported that there are various operating parameters which affect the thermal conductivity of nanofluids. In the present paper the results of several researches in the field of enhancement of nanofluid thermal conductivity have been compiled.
