Physicists have designed a novel micro heat engine that can produce maximum power at maximum efficiency1. The engine operates with a single particle whose width is one hundredth of a single human hair, says a team of researchers at the Indian Institute of Science in Bengaluru.
A conventional heat engine converts energy into work, moving a piston in a specific direction and then returning it to its original position. The efficiency with which an engine can turn heat energy into useful movement is limited. This is known as the Carnot Limit after it was proposed by physicist Nicolas Leonard Sadi Carnot in 1824.
To mimic a conventional heat engine on a microscopic scale, the scientists, led by Ajay K. Sood, took a tiny, gel-like colloidal bead and used a laser beam to direct its piston-like motion.
The team, which included Rajesh Ganapathy at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bengaluru, also used a rapidly changing electric field to cycle the engine between two states.
Under these conditions, heat dissipation reduced drastically, bringing the efficiency of the tiny engine close to 95% of the Carnot Limit. Introducing an electric field also reduced heat distribution time.
“Such a reduction allows it to operate at high efficiency, yielding a large power output even at high speeds,” says lead author Sudeesh Krishnamurthy. The advance could pave the way for more energy-efficient devices, he adds.
