Indian-American devises way to cool hybrid cars


Washington : A team of scientists led by an Indian-American has found out a new way of cooling microchips in electric and hybrid cars, aircraft, computers and other devices by understanding how the fluid overheats in tiny microchannels.

Support TwoCircles

The new type of cooling system, devised by a Purdue University team, will be used to prevent overheating of devices called insulated gate bipolar transistors — high-power switching transistors used in hybrid and electric vehicles.

The chips are required to drive electric motors, switching large amounts of power from the battery pack to electrical coils needed to accelerate a vehicle from zero to 100 km per hour in 10 seconds or less.

The high-power devices produce about four times as much heat as a conventional computer chip.

Allowing a liquid to boil in cooling systems dramatically increases how much heat can be removed, compared to simply heating a liquid to below its boiling point, said Suresh Garimella, mechanical engineering professor at Purdue University.

“One big question has always been, where is the transition from macroscale boiling to microscale boiling?” said doctoral student and study co-author Tannaz Harirchian.

“How do you define a microchannel versus a macrochannel, and at what point do we need to apply different models to design systems? Now we have an answer.”

“We have finally made sense of boiling in small-scale channels and now have a nice understanding of the physics,” said Garimella, who did his B.Tech in mechanical engineering from the Indian Institute of Technology, Chennai in 1985.

The devices also are needed for “regenerative braking,” in which the electric motors serve as generators to brake the vehicle, generating power to recharge the battery pack; to convert electrical current to run accessories in the vehicle; and to convert alternating current to direct current to charge the battery from a plug-in line, said a Purdue release.

Findings will be presented by Garimella at the conference of Thermal Investigations of ICs and Systems, or Therminic, in Leuven, Belgium on Oct 8.