Abstract:
There have been many research efforts dedicated to improving the thermophysical
characteristics of heat transfer fluids by suspending nanoparticles in different
engineering fields. Various nanoparticles have been used in these research studies,
such as organic nanoparticles, metallic nanoparticles, and metal-oxide nanoparticles.
The presented research has selected transformer oil as the base fluid, which is
responsible for the transformer's cooling and electro-insulation. The experiments were
carried out for two different nanofluids of transformer oil to identify the behaviour of
several important thermal properties. A multifunctional thermal conductivity meter
was used to measure the thermal conductivity and thermal diffusivity using the
transient hot wire method from 30 ℃ to 120 ℃. These measured values were used to
calculate the volumetric heat capacity. The flash point was measured using the
Pensky-Martens closed cup method. Following the two-step method, nanoparticles
and base fluid were first mixed, and then magnetic stirring and ultrasonication were
carried out for 1 hour and 4 hours, respectively, to prevent the agglomeration of
particles from achieving stable nanofluids. In the first experiment, a Fullerene
nanofluid sample was created with a 0.1 gL-1 concentration, but the nanofluid did not
represent any recognizable improvement in thermophysical properties compared to
the base oil. In the second attempt, three TiO2 nanofluid samples were made at weight
concentrations of 0.01 %, 0.03 %, and 0.05 %. Also, CTAB
(Cetyltrimethylammonium Bromide) was used as the surfactant to improve the
nanofluid sample's stability, according to the literature. However, TiO2 could improve
the thermal properties of transformer oil, and the greatest improvement was observed
at the 0.05 % weight fraction; CTAB also positively contributed to enhancing the
thermophysical properties.
