Commercial Pulse Tube Cryocoolers Producing 330 W and 1000 W at 77 K for Liquefaction

Fabrum Solutions and Callaghan Innovation have been developing large pulse tube cryocoolers based on Callaghan Innovation's diaphragm pressure wave generators (DPWGs). The pulse tube's lack of moving parts in combination with the DPWG's metal diaphragms produces a cost-effective, long-life, and robust cryocooler. The DPWG has had ten years of development, resulting in a series of DPWGs ranging in input powers from 0.5 to 30 kW that have been coupled to a variety of inline and coaxial pulse tubes. Two DPWGs have each had in excess of 7000 h running to date. A 330-cc DPWG was designed and manufactured to run with an inline pulse tube with a target refrigeration power of 330 W at 77 K. Absolut System carried out the pulse tube design, and manufacture was done by Fabrum Solutions, with integration and testing by Callaghan Innovation. Over 450 W of cooling power at 77 K was achieved from the cryocooler. A sealed condensation chamber was added to the cold head and connected to a Dewar via vacuum insulated lines for nitrogen liquefaction. Three such pulse tubes were combined on a single 1000-cc DPWG to produce over 1000 W at 77 K. This paper details the development of the PTC330 and PTC1000 cryocoolers from initial laboratory prototypes to commercial products, integrated into liquefiers and ready for use in applications such as liquid nitrogen production, reliquefaction of storage tank boiloff, or cooling of high-temperature superconductor applications.