Stability and Thermal Conductivity Characteristics of Carbon Nanotube based Nanofluids

Abstract

Water, ethylene glycol and engine oil are commonly used in heat exchanger applications. However, these fluids possess low thermal conductivity. The technology advancement in nanotechnology has enabled nano size particles to be included in a base fluid. This new generation of fluids is known as nanofluids. Producing a stable nanofluid with improved thermal conductivity is a challenging process. In the present study, multiwalled carbon nanotubes (MWCNT) based nanofluids with or without surfactant were investigated for their stability and thermal conductivity. The study indicates that nanofluids with added polyvinylpyrrolidone (PVP) surfactant exhibit better stability than nanofluids without surfactant. About 22.2% thermal conductivity improvement was observed for water containing 0.5wt% of MWCNT and 0.01wt% of PVP surfactant. The thermal conductivity also increases with increase of the MWCNT’s weight fraction. It can be concluded that the addition of PVP and MWCNT into base fluid (water) is vital to produce a stable nanofluid with improved thermal conductivity.