Warrier and Teja Nanoscale Research Letters 2011, 6:247 NANO REVIEW Open Access Effect of particle size on the thermal conductivity of nanofluids containing metallic nanoparticles Pramod Warrier, Amyn Teja* Abstract A one-parameter model is presented for the thermal conductivity of nanofluids containing dispersed metallic nanoparticles. The model takes into account the decrease in thermal conductivity of metal nanoparticles with decreasing size. Although literature data could be correlated well using the model, the effect of the size of the particles on the effective thermal conductivity of the nanofluid could not be elucidated from these data. Therefore, new thermal conductivity measurements are reported for six nanofluids. | Warrier and Teja Nanoscale Research Letters 2011 6 247 http content 6 1 247 o Nanoscale Research Letters a SpringerOpen Journal NANO REVIEW Open Access Effect of particle size on the thermal conductivity of nanofluids containing metallic nanoparticles Pramod Warrier Amyn Teja Abstract A one-parameter model is presented for the thermal conductivity of nanofluids containing dispersed metallic nanoparticles. The model takes into account the decrease in thermal conductivity of metal nanoparticles with decreasing size. Although literature data could be correlated well using the model the effect of the size of the particles on the effective thermal conductivity of the nanofluid could not be elucidated from these data. Therefore new thermal conductivity measurements are reported for six nanofluids containing silver nanoparticles of different sizes and volume fractions. The results provide strong evidence that the decrease in the thermal conductivity of the solid with particle size must be considered when developing models for the thermal conductivity of nanofluids. Introduction Recent interest in nanofluids stems from the work of Choi et al. 1 and Eastman et al. 2 who reported large enhancements in the thermal conductivity of common heat transfer fluids when small amounts of metallic and other nanoparticles were dispersed in these fluids. Others 3-9 have also reported large thermal conductivity enhancements in nanofluids containing metal nanoparticles although the effect of particle size in particular was not studied explicitly in these experiments. In our previous work 10-15 we have reported data for the thermal conductivity of nanofluids containing metal oxide nanoparticles and critically reviewed 15 these and other data to determine the effect of temperature base fluid properties and particle size on the thermal conductivity of the nanofluids. These studies have led us to the conclusion that the temperature dependence of the nanofluid thermal .
