Rice University postdoctoral researcher Tharangattu Narayanan, left, and graduate student Jaime Taha-Tijerina, lead authors of a ACS Nano paper on nanoparticle-infused transformer oils, show vials of the oils they say are up to 80% more efficient in keeping transformers cool. Photo: Jeff Fitlow/Rice University |
Rice University scientists have created a
nano-infused oil that could greatly enhance the ability of devices as large as
electrical transformers and as small as microelectronic components to shed
excess heat.
Research in the laboratory of Rice materials scientist Pulickel Ajayan,
which appears in ACS Nano, could
raise the efficiency of such transformer oils by as much as 80% in a way that
is both cost effective and environmentally friendly.
The Rice team headed by lead authors Jaime Taha-Tijerina, a graduate
student, and postdoctoral researcher Tharangattu Narayanan focused their
efforts on transformers for energy systems. Transformers are filled with
mineral oils that cool and insulate the windings inside, which must remain
separated from each other to keep voltage from leaking or shorting.
The researchers discovered that a very tiny amount of hexagonal boron
nitride (h-BN) particles, 2D cousins to carbon-based graphene, suspended in
standard transformer oils are highly efficient at removing heat from a system.
“We don’t need a large amount of h-BN,” Narayanan said. “We
found that 0.1 weight percentage of h-BN in transformer oil enhances it by
nearly 80%.”
“And at 0.01 weight percentage, the enhancement was around 9%,”
Taha-Tijerina said. “Even with a very low amount of material, we can
enhance the fluids without compromising the electrically insulating
properties.”
Taha-Tijerina, who was employed by a transformer manufacturer in Mexico before
coming to Rice, said others working on similar compounds are experimenting with
particles of alumina, copper oxide, and titanium oxide, but none of the
compounds has the combination of qualities exhibited by h-BN.
Narayanan said the h-BN particles, about 600 nm wide and up to five atomic layers
thick, disperse well in oil and, unlike highly conductive graphene, are highly
resistant to electricity. With help from co-author Matteo Pasquali, a Rice
professor of chemical and biomolecular engineering and of chemistry, the team
determined that the oil’s viscosity—another important quality—is minimally
affected by the presence of the nanoparticle fillers.
“Our research shows that with new materials and innovative approaches,
we can add enormous value to applications that exist today in industry,”
Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical
Engineering and Materials Science and of chemistry. “Thermal management is
a big issue in industry, but the right choice of materials is important; for
transformer cooling, one needs dispersants in oils that take heat away, yet
remain electrically insulating. Moreover, the 2D nature of the fillers keeps
them stable in oils without settling down for long periods of time.”
