Air Cycle Refrigeration Open/ Closed cycle , ULT technology by Mirai

Environmental concerns about HFCs, global warming and the resulting increasingly stringent legislation have revived interest in alternatives to existing refrigeration technologies.

The circulation system in air cycle technology is mainly composed of compressor, expander, end cooler and recuperative heat exchanger. The base of technology is that air is heated during the compression phase and cooled during expansion. The repetition of the compression and expansion cycles makes it possible to achieve and maintain ultra-low temperatures down to - 160 °C.

According to the principle of operation, air-cycle refrigeration systems are classified into the following categories:
1. Open refrigeration cycle
2. Closed refrigeration cycle

1. Open Cycle - the super-cooled air is supplied directly to the cold room. - no evaporator or auxiliary fans -the system provides its own mass flow, allowing for great temperature uniformity and distribution - unique Humidity Extraction Device ‘’HED’’ (no build-up of ice, no frequent defrost) - integrated control system (use of digital communication protocol, real-time monitoring, data archiving, remote monitoring)
Application of open cycle machine:
• storage of meat and fish
• cryotherapy use.
• biological/pharmaceutical materials storage /vaccines storage/ biobanking Closed Cycle - the ultra-cold air is circulating in a closed loop only inside the refrigeration machine. - equipped with an additional heat exchanger for the secondary working fluid -

2 Closed Loops intersect in the additional heat exchanger inside the refrigeration machine - primary loop – air; secondary – secondary medium (silicon oil), another medium is also possible as well. Application of closed-cycle machine:
• Process cooling
• Freeze Drying
• Shock freezing
• Solvent recovery / Gas liquefaction

There are particular advantages that apply to all potential applications:
- The working fluid (air) is free, environmentally benign, safe, and non-toxic.
- Use of air bearings allows for more reliable operation and significantly fewer service needs
- Air cycle equipment is extremely reliable, reducing maintenance costs and system downtime.
- When operating an air-cycle unit can also generate heat at a useful temperature. If this is used in conjunction with cooling, highly efficient processes with low energy consumption are possible.

Air-cycle technology is extremely attractive against the background of today's environmental problem.