Ultra-Low Temperature Air-Cycle Machine on Double Duty as Heat Pump

German cryotherapy provider Coolinn is using the ultra-low temperature air-cycle machine for its cryotherapy units, but also utilizes the unit’s exhaust air for heating, making it work double duty as a “heat pump.”

Coolinn started offering cryotherapy, essentially a reverse sauna without the humidity, to athletes in September 2019. The cryotherapy helps to improve performance and aid recovery from injury. The technology can also be beneficial in treating certain diseases like rheumatism.

Coolinn’s air-cycle machine, the Mirai Cold 15 from European engineering and manufacturing company Mirai Intex, uses only air as the refrigerant, as well as ambient air to remove heat (water is used to remove heat in other units). It maintains  –115°C in the main chamber and –60°C in the prechamber. At the same time it releases heated air ranging from 40 to 70°C (104 to 158°F), depending on the ambient air temperature (-10 to 20°C/14 to 68°F), respectively.

The heated air can be exhausted to the outside or recovered and distributed to the heated area. When the heated air is 70°C, “it is used partially foe heating but mainly for a ‘blow-dryer’ function,” said Gabriela Neshodova, Marketing Manager for Mirai. Clients who dry their skin before entering the ultra-cold chambers reduce the likelihood of damage to the skin, particularly after a sport session in which they perspire.

The heat output is up to 24kW (81.9KBTU/hr), Mirai said on its website.

The heat pump functionality of the unit “is very convenient and, most importantly, a money-saving way of using technology,” said Mirai.

The Mirai technology operates as an open cycle, supplying cold directly to the chamber without the need for evaporators, oil, or auxiliary fans, Mirai said. Read more about the Mirai technology here.

In addition to cryotherapy, Mirai also markets its solution to freeze drying operators, and has lately found a new market in vaccine storage during the COVID-19 pandemic.

The Mirai Cold 15 won the Innovation of the Year Award at the 2019 Accelerate Magazine Awards/Europe program. The awards recognize people and organizations that excel in advancing natural-refrigerant technologies.

The first Mirai unit was introduced at Chillventa in 2016.