There are refrigerators on the ISS. They are used both for experimental samples as well as cold storage of crew food and drink. Some are used to transport samples (and sometimes bonus ice cream) to the ISS on cargo spacecraft.
The cold storage hardware available include:
MERLIN (the Microgravity Experiment Research Locker/INcubator)
GLACIER (General Laboratory Active Cryogenic ISS Experiment Refrigerator)
POLAR research refrigerator
MELFI (Minus Eighty-Degree Laboratory Freezer for ISS)
A MERLIN refrigerator is visible in this photo of astronaut Christina Koch showing off a food warmer in the galley located in Node 1….
Although astronaut meals are designed not to need refrigeration the MERLIN’s use for food is mentioned in a NASA daily status report…
ISS On-Orbit Status December 31, 2010
CDR Kelly performed another status check on the MERLIN (Microgravity Experiment Research Locker Incubator) Galley fridge, looking for any internal condensation moisture which would require replacing desiccants. MERLIN, the Galley fridge, is used for cold storage of crew food and drink. If Scott found moisture, a change-out of the desiccant will be scheduled. Daily checks by the crew are currently required because the ground has lost insight into MERLIN due to issues with the failed ER6 (EXPRESS Rack 6) laptop software load on 12/28.
Microgravity Experiment Research Locker Incubator
MERLIN is a rear-breathing Middeck Locker replacement incubator that provides a thermally controlled environment for scientific experiments, as well as provides cold stowage transport for samples to and from the International Space Station on the Visiting Vehicles.
Cooling is accomplished via thermoelectric elements (creation of a heat difference from an electric voltage). MERLIN is capable of providing temperatures as cold as -20°C while operating with ISS water cooling or -5°C while operating with ISS air cooling. The experiment volume can be maintained to temperatures within the range of -20°C (-4°F) to +48.5°C (+119°F) with a tolerance of +/-0.5°C using either a set point or programmable temperature profile.
It is designed to operate with minimal crew interaction by most of the controls being commanded from the ground. The structural design of MERLIN allows for the internal volume of approximately 2 ft 3 in.
The General Laboratory Active Cryogenic International Space Station Experiment Refrigerator (GLACIER) is a rear-breathing or water-cooled cryogenic freezer that provides cryogenic transportation and preservation of samples requiring temperatures between +4°C (39°F) and -160°C (-301°F).
Expedition 27 astronaut Cady Coleman inserts samples into the General Laboratory Active Cryogenic ISS Experiment Refrigerator (GLACIER) in the Destiny U.S. Laboratory.
Polar is a Cold Stowage managed facility that provides transport and storage of science samples at cryogenic temperatures (-80ºC) to and from the International Space Station (ISS). Polar operates on 75 W supplied power and uses air cooling as its heat rejection method. Polar can accommodate up to 12.75 liters of sample volume
Polar is designed to operate as a hard mounted, single middeck locker equivalent within the EXPRESS Rack aboard the ISS, within the Space-X Dragon Capsule, and the Orbital Cygnus Capsule. The Polar operates as an air cooled payload in the EXPRESS Rack and Commercial off the Shelf (COTS) Vehicles.
Astronaut Kate Rubins next to Polar Facilities 2 and 4 installed in the SpaceX Dragon Commercial Resupply Services-9 (CRS-9) spacecraft for return to Earth…
The Minus Eighty-Degree Laboratory Freezer for ISS (MELFI) is a European-built experiment storage freezer for the International Space Station.
The freezer is based on the Reverse Brayton Thermodynamic Cycle which uses nitrogen gas as a working fluid. It includes four individually-controlled dewars which can be configured to support samples at temperatures between 10°C and -99°C. The three common modes of operation being -95°C, -35°C and 2°C.
Astronauts Aki Hoshide and Sunita Williams transferring MELFI samples….
Enjoying some ice cream from Earth- my first in 6 months. Double Chocolate. mmmmmmm pic.twitter.com/TcPGzA622O
— Terry Virts (@AstroTerry) April 21, 2015
Ice cream is blasting off for the crew of the International Space Station. The ice cream was confirmed as on board SpaceX's Dragon cargo capsule by NASA after a pre-launch press conference raised the possibility that it was included.
"We talked about flying ice cream," said NASA manager Michael Suffredini. "We try to bring up what we call 'bonus food' for the crew, and this is one of those flights that will have that.
The vanilla with swirled chocolate sauce ice cream cups won't melt on their three-day journey to the space station thanks to a freezer on board the Dragon capsule.
"We're very excited," SpaceX president Gwynne Shotwell told reporters. "This is the first time we are taking powered cargo up. We are taking up a GLACIER freezer, which has refrigerated science samples in it."
Footnotes