Engineers Are Developing a Zero-G Refrigerator For Space Missions

Astronauts need a fridge that is unlike the ones in our kitchens.
Derya Ozdemir

Its numerous advantages aside, being an astronaut is not an easy feat, and definitely, it is not for those who are too fond of food. The menu provided is not very comprehensive, so you wouldn't be finding oysters or waffles; however, astronauts eat a varied diet that is similar to what we eat on Earth.

For extended missions to the Moon and beyond, however, what astronauts need is a refrigerator. Understandably, the refrigerators we use at home aren't suitable to work in zero gravity and can't work upside down, which makes coming up with a new design pretty important.

To meet the tight deadline for future space missions, engineers from Purdue University, Air Squared Inc., and Whirlpool Corporation are working on designing a refrigerator that works in zero gravity and can operate in different orientations. Their refrigerator design will be tested in a weightless research lab, and according to the data, the team will determine whether the design is ready for space.

It will, of course, typically offer astronauts longer-lasting and more nutritious food on their voyages to other planets. This is especially important since the canned and dried food that astronauts currently eat has a shelf life of only about three years.

Funded by NASA's Small Business Innovation Research (SBIR) program, the project has a goal of providing astronauts food that could last five to six years.

 "Astronauts need to have better quality food that they can take along. And so that’s where a refrigerator comes into play. But it’s still a relatively novel technology for space," said Eckhard Groll, a professor and head of Purdue’s School of Mechanical Engineering, in a press release by the university.

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A Zero-G refrigerator to keep astronauts fed

The ISS astronauts currently use cooling systems to conduct experiments and store biological samples, and these refrigerators consume higher amounts of energy than those on Earth. The Purdue team has built a refrigerator prototype that will fly during one of the team's three experiments. 

Engineers Are Developing a Zero-G Refrigerator For Space Missions
Eckhard Groll (left) and Leon Brendel. Source: Purdue University/Jared Pike

 "When I jumped on this project, it wasn’t completely clear what the problems would be since there haven’t been many vapor compression refrigeration experiments in microgravity in the past," said Leon Brendel, a Purdue Ph.D. student in mechanical engineering. "In a typical refrigerator, gravity helps to keep liquid and vapor where they are supposed to be. Similarly, the oil lubrication system inside of a refrigerator’s compressor is gravity-based. When bringing new technology into space, making the entire system reliable in zero gravity is key."

Since a zero-gravity environment affects the flow of oil throughout the fridge, an oil-free compress was developed by Air Squared, Inc. 

Engineers Are Developing a Zero-G Refrigerator For Space Missions
The three experiments: A prototype for possible use on the ISS (left), a setup to explore the prototype’s vulnerability to liquid flooding (center), a larger version of the prototype with sensors to capture gravity's effects on the vapor compression cycles (right). Source: Purdue University/Air Squared, Inc.

The engineers have built two other experiments, and they will be tested extensively to see whether the solutions used are reliable enough for space missions. The experiments will also entail a larger version of the prototype with sensors to measure the effects of gravity on the vapor compression cycles, which is one of the many refrigeration cycles where the refrigerant experiences phase changes.

These experiments are crucial since if successful, they'll be clearing the way for astronauts to have a reliable refrigerator in space.

"During the last two years of this project, we have made tremendous strides in moving the technology forward," Groll said. "If these parabolic flights check out as we imagine they will and prove our system works in microgravity, we’re just a couple years away from having a refrigerator for spaceflight."

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