ahmad azari - Islamic Azad University Omidieh Branch, I.R. Iran Chemical Engineering Department, AmirKabir University of Technology, Mahshahr Campus, I. R. Iran
mansour kalbasi - Chemical Engineering Department, AmirKabir University of Technology, Mahshahr Campus, I. R. Iran
masoud rahimi - CFD Research Center, Chemical Engineering Department, Razi University, Taghe Bostan, Kermanshah, Iran

The nano particles have demonstrated great potential to improve the heat transfer characteristics of heat transfer fluids. Previously developed correlations have not completely predicted the anomalous increase in the thermal conductivity of nanofluids. In this paper, possible parameters responsible for this increase were studied. The heat transfer profile in the nanolayer region was combined with other parameters such as volume fraction, particle radius, thermal conductivity of the fluid, particle and nanolayer, to formulate a new correlation. Results predicting the thermal conductivity of nanofluids using the new correlation were compared with experimental results as well as studies by other researchers. Overall the comparison of the results obtained for the CuO/Water and TiO2/Water nanofluids studied shows that the correlation proposed is in closest proximity in predicting the experimental results for the thermal conductivity of a nanofluid. Also a parametric study to understand how a number of factors affect the thermal conductivity of nanofluids was performed using the newly developed correlation and led to some important conclusions

Nanofluid, Effective Thermal Conductivity, Nanoparticle, Nanolayer, modelling