Stirling Ultracold

Stirling Ultracold is an innovative "no compressors" green sustainable solution for your ultra low temperature storage requirements.

Ultracold refrigeration is an essential requirement for the storage of Biological material and for many years cascade refigeration systems with powerful compressors (temperatures of -70 to -86deg C ) in Ultra Low temperature refrigerators  have been used to meet these requirements. Whilst this is still by far the most popular storage solution, they are not without their problems. These freezers  over the years have required  CFC and HCFC refrigerants which are harmful to the environment and whilst there has been a move away from these refrigerants to CFC free and HCFC free refrigerants the change has been disruptive to the industry and in particular the highly regulated Pharmaceutical and Biotechnology Industry. In addition to this the cascade refrigeration system leads to peaks and trough s in temperature control which can lead to validation difficulties.

Stirling Ultracold operate a “No compressor system” which has transformed Ultra Low Temperature Refrigeration


How does the Stirling engine revolutionize ULT system reliability?

  • The advanced linear motor and thermosiphon system design is inherently more efficient and reliable, with only two moving parts.
  • The two moving parts never wear because gas bearings eliminate all physical contact (friction) during motion, like a puck on an air hockey table.
  • The two moving parts, the piston and the displacer, expand and compress helium in the engine, absorbing heat from the thermosiphon, keeping the cabinet cold.
  • There is no oil to clog up the system or lubrication levels to maintain.
  • The system requires virtually no maintenance.
  • Continuous modulation controls temperature like cruise control maintains speed in your vehicle. Compressor start/stop cycles would be like controlling your car’s speed by cycling the ignition on and off. These excess mechanical and electrical stress leads to failures and higher electrical usage.
  • The gravity-fed thermosiphon “hugs” the inner cabinet and is charged with 100 percent natural R170.
  • The thermosiphon is isothermal, driving superior interior temperature uniformity without high pressure or pumps.
  • Similar to steam condensing on the lid of a pot of boiling water, R170 refrigerant is condensed to liquid near the “expansion zone” of the Stirling engine and flows down the thermosiphon via gravity. As it absorbs heat from the interior cabinet of the freezer, it turns to gas, rising back up the tube where it is cooled back to a liquid and the process repeats.


Stirling Product Range Brochures


  • SU780XLE            Upright Ultra-Low Temperature Freezer (780L capacity)  -86C to -20C
  • SU105E-240          Undercounter Ultra-Low Temperature Freezer (105 Liters capacity)
  • ULT25NE              -86ºC to -20ºC Ultra-Low Temperature Freezer,  Includes Lid, Port Sealant, stopper,  keys, basket.


Product data Sheets

  • SU780XLE DS            Upright Ultra-Low Temperature Freezer (780L capacity)  -86C to -20C
  • SU105E-240 DS          Undercounter Ultra-Low Temperature Freezer (105 Liters capacity)
  • ULT25NE DS              -86ºC to -20ºC Ultra-Low Temperature Freezer,  Includes Lid, Port Sealant, stopper,  keys, basket.


Please contact us if you would like further details on the Stirling Ultracold  range of products.

Stirling Ultracold website

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