Investigation of Thermal Conductivity and Viscosity of Carbon Nanotubes–Ethylene Glycol Nanofluids

Abstract

Abstract Conventional fluids used for heat transfer applications in automobiles limit the performance enhancement and compactness of the heat exchangers. These problems can be overcome by using the technology of nanofluids. The objectives of this work are to prepare nanofluids and to study their dynamic viscosity and thermal conductivity. Chemically treated carbon nanotubes (CNTs) were added with ethylene glycol (EG) and sonicated using a bath sonicator to have a homogeneous dispersion of CNTs in EG. In this study, the nanofluids were prepared with different concentrations of CNTs varying from 0.12 to 0.4 wt%. The dynamic viscosity of nanofluids was measured using a rheometer over a temperature range of 25°C to 60°C. It was observed that the viscosity of nanofluids decreases with an increase of temperature and enhances with CNT concentration. The nanofluid follows the characteristic behavior of Newtonian fluids. A linear rise in thermal conductivity of ethylene glycol was observed with an increase of CNT concentration. It is concluded that EG–CNT nanofluids are promising to meet the challenges required by automobile systems. Acknowledgments The authors gratefully acknowledge FCT, Portugal, and DST, India, for funding through projects PTDC/EME-MFE/66482/2006 and SR/FTP/ETP-051/2009, respectively. The authors also thank Mr. Saikia, Mr. Sharma, and Mr. Basumatary of the Mechanical Engineering Department and Mr. Kautabh Deka of the Chemical Engineering Department at IIT Guwahati for their support in carrying out these experiments.