Water-based nanofluids were prepared with multi walled carbon nanotubes （MWCNTs） of different lengths in concentrations of 0,1,0,25 and 0,5 vol%, To improve their dispersibility, pristine MWCNTs were functionalized ...Water-based nanofluids were prepared with multi walled carbon nanotubes （MWCNTs） of different lengths in concentrations of 0,1,0,25 and 0,5 vol%, To improve their dispersibility, pristine MWCNTs were functionalized and cut into small lengths by reflux in an oxidizing mixture of 3：1 sulfuric and nitric acids, The initial length of the carbon nanotubes （CNTs; 10-15 μm） was reduced to 203, 171 and 134nm after 1, 2 and 4 h of reflux, respectively, Surface modification and the reduced length of the CNTs, improved the stability of the nanofluids with no significant sedimentation observed after 80 days. Furthermore, the thermal conductivities of nanofluids prepared using refluxed CNTs, were higher than that of the pristine CNTs. The thermal conductivity also increased with the nanofluid temperature, The nanofluid prepared with 1 h refluxed CNTs had the highest thermal conductivity, The enhanced thermal conductivity and stabilitv of the nanofluids was attributed to the decreased length of CNTs.展开更多
基金Shahid-Chamran University of Ahvaz for the financial support of this workNational Iranian South Oil Company(NISOC) for their help and assistance
文摘Water-based nanofluids were prepared with multi walled carbon nanotubes （MWCNTs） of different lengths in concentrations of 0,1,0,25 and 0,5 vol%, To improve their dispersibility, pristine MWCNTs were functionalized and cut into small lengths by reflux in an oxidizing mixture of 3：1 sulfuric and nitric acids, The initial length of the carbon nanotubes （CNTs; 10-15 μm） was reduced to 203, 171 and 134nm after 1, 2 and 4 h of reflux, respectively, Surface modification and the reduced length of the CNTs, improved the stability of the nanofluids with no significant sedimentation observed after 80 days. Furthermore, the thermal conductivities of nanofluids prepared using refluxed CNTs, were higher than that of the pristine CNTs. The thermal conductivity also increased with the nanofluid temperature, The nanofluid prepared with 1 h refluxed CNTs had the highest thermal conductivity, The enhanced thermal conductivity and stabilitv of the nanofluids was attributed to the decreased length of CNTs.
