By using a pressurized cold gaseous helium loop it is possible to “decouple” the cooler from the application. This can be favourable in cases where it is very difficult to directly connect a cooler to an application due to whatever restriction there may be, such as safety, space, sound, vibration, rotating devices etc.
Another advantage of gaseous helium is its operation window: it can be used at any temperature between ambient down to approx. 10 Kelvin. Restrictions that may arise with other fluids like undesirable liquefaction or freezing are no issue with helium gas. If the gas is pressurized (preferably in a range of 10-20 barg), sufficient density is available for proper heat transfer.
Stirling’s Cryogenerators (one and two stage) can be built with a heat exchanger to work with gaseous helium as a coolant, working in a temperature range from 150 down to 18 Kelvin using an integrated CryoFan. This eliminates the need for the supply and design of a separate Cryostat that will hold a cryocooler, heat exchanger and CryoFan (or pump). With a Stirling Cryogenerator with integrated CryoFan, cold helium gas will flow directly out of the cooler. Only a connection (vacuum jacketed) between the cooler and the application is needed to complete the system.
Stirling CryoFans are used to efficiently transport the gaseous helium from the (Stirling) cryocooler to the customer’s application and back. Depending on the required volume flow and other process conditions the appropriate CryoFan can be selected.
Applications and markets where helium gas cooling systems can be useful: