Cold air refrigeration technology by Mirai Intex


The Mirai Intex cold air refrigeration technology works oil-free with only air as a refrigerant. To do this, Mirai Intex has developed a unique turbo compressor expander. This is air-bearing and the compressor and expansion wheel (expander) are on one shaft, so that the energy of the expansion of the compression is fed back. The turbo compressor-expander unit is designed with air bearings, so that no oil is required. With the frequency converter control, any temperature can be controlled and regulated to an accuracy of 0.5 K. As standard, the machines can regulate any temperature from -30°C to -110°C. In special versions, the range can be extended down to -160°C with air as the refrigerant. The pressures in the open machines are a maximum of 1 bar, which is less than the pressure of a bicycle tire.

Air as a refrigerant is free, non-hazardous and free from regulations.

The Cycle - Joule Process

Air is sucked in from the cooling room or the heat exchanger and compressed (1→2). This increases the pressure and temperature. The set pressure remains constant until it is relieved. In the gas cooler, the process temperature is cooled by ambient air (2→3). In the internal heat exchanger, the so-called recuperator, energy is recovered, the warmer air from point 3 heats the sucked-in air from point 1. Conversely, the air from 3→4 cools down further. This is followed by a work-performing expansion in a turbo expander. The work done during expansion is reflected in a reduction in pressure and temperature. In contrast to the steam cooling process, the energy absorption does not take place through the phase change, but through the heating of the air (5→6). Air is continuously sucked out of the consumer and in the recuperator cools the air that is already in the circuit (6→1). The cycle then starts again from the beginning (1). In the case of cold air machines, the expander is mounted on a shaft with the frequency-controlled electric motor and the compressor. With this arrangement, the work gained in the work-performing expansion of the compression is supplied. The shaft is air-bearing, so operation is oil-free.

Benefits of Mirai Intex cold air refrigeration technology at a glance.

Environmentally friendly

Air as refrigerant / No refilling required / Environmentally friendly

oil free

No oil in the system thanks to air bearings / Lower costs

compliance with the law

Compliance with the law Compliance with all international standards/regulations

stability of operation

Stable cooling performance when operating with cooling water

Safe solution

No chemical substances / No fire or explosion hazard

No vibrations and greatly reduced noise

No vibration and greatly reduced Noise / Turbo engine design reduces noise and vibration

High reliability

One of the most common causes of failure of refrigeration systems is compressor damage caused by the entry of liquid refrigerant into the compressor or by insufficient lubrication, e.g. due to displaced oil or wear. Another common cause of failure is wear and tear from vibration, such as failure of small oil lines. In cascade systems for low-temperature applications, there is also the fact that several compressor circuits have to work simultaneously and influence each other. The cold air chillers have no phase change, no oil and, thanks to the air bearing, almost wear-free operation without vibration. This technology has a high level of reliability.

Highly efficient in the field of low-temperature technology

We carried out a detailed study of the energy efficiency of low-temperature refrigeration technology and were able to prove that cold-air refrigeration technology is highly efficient in the field of low-temperature technology. The detailed investigation can be found in our ULT report.

The systems are essentially available in two versions.

as a closed machine
as a closed machine
  • with integrated heat exchanger
  • 10 to 80 kW motor power
  • -40°C -110°C temperature range
  • Particularly suitable for process cooling such as freeze drying
as an open machine
as an open machine
  • with automatic defrosting
  • 10 to 22 kW motor power
  • -40°C -110°C temperature range
  • Particularly suitable for room cooling such as storage rooms

Here you will find our energy comparison for low-temperature technology.

Here you will find our services.

Do you have questions about technology or want to book a training session? Please contact us.

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