Preparation and Heat Transfer Properties of Nanoparticle-in-Transformer Oil Dispersions as Advanced Energy-efficient Coolants

고효율 냉각용 나노분말/절연유 분산액의 제조 및 열전달특성

The purposes of the present study are to produce a high thermal efficient of oil-based nanofluids which can be used as ultra-high voltage transformer oil, and to investigate their thermal and physical properties under static and dynamic conditions. Three kinds of nanofluids are prepared by dispersing $Al_2O_3$ or AlN nanoparticles in transformer oil. The thermal conductivities of the nanoparticles-oil mixtures increase with temperature, particle volume concentration and thermal conductivity of solid particle itself. It was quite important to eliminate $H_2O$ as byproducts of esterification and excess oleic acid which did not form stable chemical bonds with powder surface to get high dispersion stability.