Stirling Cryogenics
Institute Nazionale di Fisica Nucleare, Italy
In April 2009, Stirling Cryogenics has successfully commissioned the INFN ICARUS- Cryogenic Cooling system for cooling two liquid Argon detectors. The Icarus Experiment is detecting neutrino’s coming from the sun, with the goal to determine the physical properties of the neutrino’s.
This experiment is located inside the underground laboratories of INFN, in Gran Sasso, Italy. The timeframe of the experiment is 10 years and during this period the two 100,000l Liquid Argon detectors have to be kept at a temperature of exactly 89K.
Video animation
The ICARUS cooling system is designed as a stand alone system with a maximum of redundancy. The 8 Stirling cryogenerators produce a nett cooling power of 18-30kW and has a build-in intelligence which enables the cryogenerators to decide themselves whether they are active or not. Two additional Stirling Cryogenerators provide the redundancy required.
The liquid Argon is cooled by a secondary cooling loop of liquid nitrogen at a pressure of 2.5 bar. In total 30,000 l liquid nitrogen provides enough thermal mass to damp the temperature changes due to fluctuation of the heat load in the liquid Argon detector.
Besides the Stirling Cryogenerators, the cooling loop is equipepd with liquid nitrogen pumps, pumping vessels, phase seperators and storage vessels. Turning on and off the Stirling Cryogenerators make it possible to produce the cold most efficiently. The short time to full production (10 minutes) gives a very fast reponse time on heat load changes.
The total system is remotely monitored. The maintenance on all the system components can be performed without shutting down. Even the liquid nitrogen pipelines are fully redundant. In all situations the minimum cooling power of 18 kW is assured