Investigation of electrical breakdown and heat transfer properties of coconut oil-based nanofluids

This paper presents the evaluation of two grades of coconut oil -RBD (refined, bleached, and deodorized) and virgin coconut oil, plus MIDEL eN1215 as standard natural ester, by dispersing Zinc oxide (ZnO) nanoparticles to improve their breakdown strength and cooling properties. It is shown that a stable nanofluid can be realized at different concentrations of ZnO nanoparticles with or without Oleic acid as a surfactant depending upon the moisture content in oil. Dry and wet nanofluids at 1 and 0.04-0.05 wt% nanoparticles concentration, respec-tively, showed increased AC breakdown voltage w.r.t individual base oils. As the temperature is raised to 85 degrees C, the increase in AC breakdown voltage has been insignificant except for wet oils, wherein the AC breakdown voltage increases by 20-36 %. RBD coconut oil shows better viscosity and heat transfer properties, and the latter enhances further by the addition of ZnO nanoparticles. Further, the resistance to thermal aging of various nanofluids at optimum wt% of nanoparticles in terms of various physical (viscosity, pour point, flash point) and electrical properties (resistivity, dissipation factor, AC breakdown voltage) have also been analyzed and discussed.

Automated summary

This paper evaluates the improvement in breakdown strength and cooling properties of two grades of coconut oil - RBD and virgin coconut oil, along with MIDEL eN1215 as a standard natural ester, by dispersing Zinc oxide (ZnO) nanoparticles. It is found that stable nanofluid can be achieved with different concentrations of ZnO nanoparticles depending on the moisture content in the oil. The addition of ZnO nanoparticles enhances the viscosity and heat transfer properties of the coconut oil.