4505

4239

كارشناسي ارشد

شيمي فيزيك

اصفهان:دانشگاه صنعتي اصفهان.دانشكده شيمي

1387

دوازده،116 ص:مصور،نمودار،جدول.

ص.ع به: فارسي و انگليسي

عزت كشاورزي،يوسف غايب

بهزاد رضايي،حسين فرخ پور

1396/09/12

كتابنامه

شيمي

ID4239

به فارسي و انگليسي:قابل رويت در نسخه ديجيتال

Abstract Carbon nanotubes have attracted much attention because of their unique structure andremarkable mechanical and electrical properties One of the specific properties of carbonnanotube is unusually high thermal conductivity In this study we have prepared thenanofluids with high thermal conductivity by dispersion of multiwalled carbon nanotubesin water Preparation stable and uniform dispersion of carbon nanotubes in the most fluidsis so difficult because of the aggregation of carbon nanotubes We were used thefunctionalization technique to produce the hydrophilic groups to the surfaces of carbonnanotubes and make a stable and uniform suspension of carbon nanotubes Duringtreatment MWNT with H2O2 and mixture of HSO4 and HNO3 were attached hydroxyl andcarboxyl groups to the surfaces of MWNT respectively In order to disperse nanotubes inwater we were used ultrasonic generator Hydroxylated MWNT in water have morethermal conductivity enhancement in comparison with the carboxylated one Also we havestudied the effect of concentration of carbon nanotubes and the duration of sonication tothe thermal conductivity of nanofluids The results show that the thermal conductivityenhancement increases with concentration In addition the duration of sonication stronglyaffects on the thermal conductivity of suspension and exits the optimum time sonication inwhich we have the maximum thermal conductivity enhancement The results show thatThe optimum time of sonication decrease with concentration for 0 02 to 0 1 mass ofcarbon nanotubes but at higher weight loading the optimum time is fixed at 10 min SEMimages show the forming of the three dimensional network of carbon nanotubes in theoptimum time sonication cause to the more thermal conductivity enhancement and stabilityof nanofluids We were obtained the variation of thermal conductivity of nanofluids afterthe sonication stopped to estimate the stability of suspensions Although the thermalconductivity of suspension right after sonication increase by the increased concentration ofcarbon nanotubes but reduce the stability of suspension We have also studied the thermalconductivity of mixture nanofluid containing titanium oxide and three kinds of carbonnanotubes The TiO2 nanoparticles may be agglomerated to the surface of carboxylatedMWNT and increases the thermal conductivity of nanofluid but Hydroxylated MWNTentangle around TiO2 nanocluster and form congeries so it causes a decrease in thermalconductivity enhancement It is also possible that TiO2 connected to the carbon nanotubesat the one or two end when mixture is heated

عزت كشاورزي،يوسف غايب

بهزاد رضايي،حسين فرخ پور