Investigation into thermal conductivity of palm kernel fibre nanofluids with mixture of ethylene glycol/water as base fluid

Abstract

Nanofluids have been found to possess enhanced thermo-physical properties such as thermal conductivity, heat capacity, as well as convective heat transfer coefficients compared to conventional heat transfer fluids like water, ethylene glycol and oil. The high level of hazards involved in the use of metallic nanoparticle in nanofluid research is a source of worry since there are reported literatures showing damaging effects of metal oxides to human cells. In this paper, a readily available bio–based Palm kernel nano-fibres (nanoparticle) were produced by first washing the raw fibre material with caustic soda (NaOH) to remove the residue palm oil and sundried for 10 days. The dried palm kernel fibre was ball milled for 24 hours and the resulting nanoscale fibre particles were dispersed into mixtures of water and ethylene glycol (50:50) as base fluid to form palm kernel fibre nanofluid with volume concentrations of 0.1, 0.2, 0.3, 0.4 and 0.5 %. Images of Scanning and transmission electron microscopy revealed a nearly spherical particle shape and a particle size of 100 nm. Thermal conductivity experiments were conducted in temperature range of 10 to 60 °C. Results showed that thermal conductivity of the nanofluid increased with increase in volume concentrations and temperature. An enhancement in thermal conductivity of 16.1 % was recorded for volume concentration of 0.5 %. The Maxwell, Hamilton and Crosser and Wasp models over predicted the thermal conductivity of palm kernel fibre nanofluid.