Why is it difficult to develop a space refrigerator?

In modern life, a refrigerator for long-term storage of food is indispensable. Refrigerators are essential for life in space, where food replenishment opportunities are limited, but it is difficult to develop refrigerators that function fully in space. A research team of mechanical engineering at Purdue University is jointly developing such a space refrigerator with NASA.

NASA astronaut Victor Glover, who completed his mission on the International Space Station for 168 days in May 2021, said that the astronaut refrigerator really boosts the morale of the ISS crew.

There are many facilities on the International Space Station that can cool down to minus 160 degrees, but these are incubators for space experiments and cannot be used for food storage to prevent contamination. The refrigerator that astronauts can personally use is not a high-spec refrigerator for experiments, but a simple one that emphasizes convenience, maintenance, and energy efficiency that can be operated for a long time. In other words, it should be a refrigerator that seems to be used on the ground, but it is difficult to operate a regular refrigerator in a microgravity environment like space.

Most refrigerators used in households adopt the gas compression method. When the liquid refrigerant circulating through the gas compression cooling tube evaporates, it absorbs heat from the inside of the refrigerator as heat of vaporization and releases it to the outside, cooling the inside of the refrigerator. The vaporized refrigerant becomes a high-temperature and high-pressure gas in the compressor and condenses into a liquid in the condenser. Oil is used in the moving part of the compressor, and the oil that has fallen into the oil pan installed in the compressor is circulated and used again.

However, this oil cycle requires gravity to be established. In a microgravity environment such as the ISS, it is difficult to maintain normal operation because the oil may be scattered in various directions without falling into the oil pan, causing the compressor to burn.

Purdue University’s mechanical engineering research team focused on oil-free compressors used to move surgical instruments and life-saving ventilators in the medical field. In addition, to cool the compressor, a cooling water circulation water cooling system is adopted outside the moving part.

In addition, the research team conducted verification by turning the refrigerator itself to confirm whether the refrigerator was placed on its side or turned upside down. In addition, an experiment was carried out 30 times to check whether an experimental refrigerator was mounted on an aircraft and operated properly in a 20-second microgravity environment caused by a parabolic fall. As a result, it was confirmed that the experimental refrigerator works properly regardless of whether it is lifted in any direction or placed under microgravity conditions.

The research team said that the goal of the research project is to prevent astronauts from repairing the refrigerator, but it is not known how continuously the refrigerator can be used in space. said he had not yet experienced it. Related information can be found here.



Through the monthly AHC PC and HowPC magazine era, he has watched 'technology age' in online IT media such as ZDNet, electronic newspaper Internet manager, editor of Consumer Journal Ivers, TechHolic publisher, and editor of Venture Square. I am curious about this market that is still full of vitality.

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