Thomas Frank

Future of ultra-low temperature refrigeration: -115°C cold sauna and -80°C storage room using ambient air as a refrigerant

Refolution is a European engineering company that specialises in refrigeration systems using R279 refrigerant (air), including applications such as cryo-saunas (wellness), freeze-drying and low-temperature storage of medicines and other perishable goods.

In September 2019, Refolution built a cold sauna for COOLINN, in Karlsruhe, Germany. The system employs an air cycle refrigeration machine with an oil-free air-mounted turbo-expander, and a chamber constructed with hook-connected PU-foam panels, integrated vacuum shield and a second isolation shield. Over a period of six months the Refolution team confirmed that the system can run permanently on low temperatures of -115°C during the day and -40°C at night. Other features include a double-insulated floor, a sloping base for easy draining of water and cleaning, a special air distribution system, and an innovative de-icing system that results in a dew-point of 15K below room temperature.

In 2020, Refolution conducted an energy analysis for ultra-low temperature (-40°C to -110°C) technologies that showed air refrigeration is one of the most efficient solutions. Also in 2020 they added a heat recovery system that allows COOLINN to use waste heat from the refrigeration machine to dry customers after sports or on rainy days and heat the complete lounge on cold days.

This presentation will describe the cold sauna and air refrigeration technology in detail. It will also explore further uses of this innovation such as the storage of COVID-19 vaccines. 

About Frank
Frank is a chemical engineer (Dipl. Ing.) and certified senior project manager (IPMA level B) with experience in the field of refrigeration. For more than 10 years he has worked in different fields of industrial refrigeration, from process cooling for chemical plants to food storage and environmental simulation. 

In 2019, he founded Refolution, an engineering office that uses deep knowledge of refrigeration and analytic process understanding to develop new processes in different fields and promote the use of natural refrigerants.