INFN, Italy

In April 2009, Stirling Cryogenics successfully designed and built a cooling system for the ICARUS project, which is being carrried out by the INFN in Italy. This fully self-controlled system of ten 4kW cryogenerators was built to cool 400,000 liters of liquid Argon to exactly 94K for at least 10 years. The ICARUS experiment detects neutrinos from the sun in order to determine their physical properties.

This experiment is being conducted at the underground laboratories of the INFN, in Gran Sasso, Italy. The timeframe of the experiment is 10 years and during this period the two huge liquid argon detectors must be kept at a temperature of exactly 94K.

The ICARUS cooling system is designed as a stand-alone system with a maximum of redundancy. Ten Stirling cryogenerators produce a net cooling power of 40kW. A control system continuously monitors the cryogenerators’ activity. Two additional Stirling cryogenerators provide additional redundancy.

Video ICARUS project INFN

The liquid argon is cooled by a secondary cooling loop of liquid nitrogen at a pressure of 2.5 bar. A total of 30,000 liters of liquid nitrogen provide enough thermal mass to maintain a stable temperature and counter the temperature variations caused by the fluctuation of the heat load of the liquid Argon detector.

The whole project as designed and delivered by Stirling Cryogenics comprises the Stirling cryogenerators and a cooling loop that is equipped with liquid nitrogen pumps, pumping vessels, phase separators and storage vessels. This is all controlled with the help of fully automatic monitoring and end-status reporting. Turning the Stirling cryogenerators on and off makes it possible to produce the cold efficiently. The short time to full production (10 minutes) ensures a very fast reaction time to heat load changes.

The total system is monitored remotely and maintenance on all the system components can be performed without shutting down. A minimum cooling power of 18 kW is assured under all circumstances.

We have a full report on the design and 1st year of operation of this refrigeration system available. Please send us an e-mail if you want to receive the full report.