Yi Zheng of the College of Mechanical and Industrial Engineering spends summers at NASA
Summer break space race keeps Northeastern Professor eyes on the future technology
In the space business – heat is a problem. Too much heat on space crafts and rovers, and components will crack, break down, or even make batteries explode. It’s why spacecrafts are regularly equipped with heat shields. Too little heat in space, and electronic components won’t work in the frigid cold. It was the case with the Mars Opportunity rover, whose failed heaters after a dust storm froze its internal electronics and ended its mission to find water on the red planet.
That’s where Yi Zheng, an associate professor in Northeastern’s Department of Mechanical and Industrial Engineering, comes in.
From a device that sops up heat to charge electric batteries on spaceships and Mars rover to a near fireproof, heat-stabilizing gel that can stop old spaceship batteries from getting hot and exploding, Zheng has worked on these and other projects with the goal of minimizing heat in space.
“I teach engineering, but at heart, I’m an engineer too,” said Zheng. who spent his past six summers working on all those projects for NASA at its Glenn Research Center in Cleveland, Ohio. It’s where engineers design and test new space and aeronautics technology.
He does these annual 10-week stints because working in the agency’s labs allows him to see theory meet real-life engineering challenges.
For NASA, the idea is to bring in fresh eyes from an experienced university professor to help space engineers solve real problems, space agency officials said.
Northeastern professor Yingzi Lin, the chair of College of Engineering, said that having professors out in the “real world” working with NASA engineers is a feather in the cap for the university, helping to build the university’s prestige.
“It’s a good collaboration for us and may lead to potentially more with NASA,” Lin said. “It also helps professors to go out there, have new experiences, and bring them back to the classroom for our students. There’s a lot of interest in space.”
NASA senior engineer Michael Halbig helped select Zheng to come to the summer program out of more than two dozen applications.
“He is strong on thermal analysis modeling and thermal management,” Halbig said of Zheng. “He’s a great communicator, a diligent worker.”
Zheng’s first major project was to help develop a kind of electric “waffer” or small disc that can harvest wasted heat emitted from the electronics and power systems and turn it into extra electricity. The technology, called thermal photovoltaic cells, can also drink in light and invisible electromagnetic radiation and convert it to electricity too, Zheng said.
A patent filed in 2022 is pending for his team’s work on these cells, he said.
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In another project, he and his team take ultrasmall particles of carbon such as pure carbon nanotubes — which are tiny cylinder-shaped molecules 100,000 times smaller than a human hair — and combine them with paraffin waxes to create PCMs or advanced Phase Change Materials that help keep batteries from getting too hot.
Such material has high thermal, or heat, stability, Zheng said, and that means it can protect lithium-ion batteries in space or on Earth from what scientists call “thermal runaway.”
That’s an unstoppable chain reaction inside the battery, where temperatures increase fast – about 70 degrees Fahrenheit a minute – and can lead to smoke and fire and “possibly they can explode,” he explained.
Such things happen on Earth when electric car batteries spontaneously heat up and catch fire, Zheng and other scientists said.
“I designed a cooling system to deal with that,” Zheng said. “It also elongates the operating life of a battery.”
The developments Zheng worked on “show a lot of promise,” said Mrityunjay Singh, chief scientist of NASA’s research and development division at the Ohio Aerospace Institute, who worked with Zheng at the Glenn Research Center.
“It’s true that a lot of lithium-ion batteries catch fire,” said Singh, who is also an affiliated faculty member in Northeastern’s College of Engineering. “So how do you cool it so thermal runaway doesn’t happen?”
This past summer Zheng was assigned a new project by the space agency. Zheng was tasked with developing stronger, longer-lasting ceramics for use in space and jet propulsion systems to make, among other things, lighter, heat resistant turbine blades or for other components.
The turbine blades spin and push out air and fuel exhaust superheated to almost 2,000 degrees Fahrenheit. Over time, the heat causes the blades and ceramic components to crack or break, Singh and other engineers said.
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Halbig said materials Zheng has helped develop might go into field tests as soon as next summer.
Zheng said that one day this past summer magnified what he feels working at NASA and he hopes to return next year.
He was invited out of the lab to go see a giant space rocket engine up close, at a remote NASA testing facility, where, on a whim, he stood inside a 50-foot tall space rocket engine. It was his first time seeing one up close.
“I think part of my emotional response came from remembering my childhood dream,” he said. “I wanted to become a scientist… Working at NASA reminded me how far that childhood dream has taken me.”
