the influence of decorated multi walled carbon nanotubes with tio2 nanoparticles on the thermal conductivity of water based nanofluids

in this paper, we report for the first time the thermal conductivity behavior of nanofluids containing mwcnts which decorated with different amount of tio₂ nanoparticles. for this purpose we synthesis the tio₂ nanoparticles and decorated mwcnts with different amount of tio₂ nanoparticles using hydrolysis method. the samples are characterized by transmission electron microscopy (tem). tem image confirmed that the ends of mwcnts successfully opened. meainwhile acid treatment leads to the cutting of mwcnts to the short length and the outer surface of mwcnts successfully decorated withtio₂ nanoparticles. measurements of thermal conductivity behavior of nanofluids were carried out in the range of temperature varying from 25 to 70 °c. the mass fraction of the tio₂ nanoparticles, mwcnts and decorated multi walled carbon nanotubes with tio₂ nanoparticles in water is 0.25, 0.5, 1 and 1.5 %wt..the results of thermal conductivity behavior of nanofluids revealed that the thermal conductivity and enhancement ratio of thermal conductivity of mwcnts- tio₂ at different amount of tio₂ nanoparticles are higher than those of tio₂ and mwcnts nanofluids. temperature and weight fraction dependence study also show that the thermal conductivity of all nanofluids increases with temperature and weight fraction. however the influence of temperature is more significant than that of weight fraction.