Design of a Reliable Reverse Turbo Brayton Cryocooler

RTI will develop a highly reliable, single-stage reverse turbo Brayton cycle (RTBC) cryocooler for space based applications. While ensuring a high reliability, the proposed design also delivers a relatively high coefficient of performance (COP), compactsize and light weight. The reliability will be ensured through the use of components and techniques that have been proven over years of commercial applications to be more reliable compared to the alternatives. The key enabling concepts/components includecentrifugal compressor, a DC cryocooling cycle, gas foil bearings and MEMS-fabricated recuperative and cold-head heat exchangers. Phase I effort will focus on the key components for high reliability: centrifugal compressor and gas foil bearings. Thiscompressor is expected to run at 150,000 rpm, be 6 cm (2.4 inch) in diameter and 7 cm (2.8 inch) in length and weigh about 0.4 kg (0.9 lb), and can be integrated to gas-foil bearings. The Phase II goal is to integrate the compressor with acustom-designed, efficient motor, control electronics and gas foil bearings with a target value of 80% for the compressor isentropic efficiency at a pressure ratio of 1.75. Eventual goal is to have a complete, reliable RTBC cryocooler for 20 W of coolingat 80 K at a minimum COP of 0.12. The proposed project offers a reliable, compact, light-weight and highly efficient cryocooler that can be a critical component in Space Based Infrared Systems-Low (SBIRS-Low) and hence for Ballistic Missile DefenseSystem (BMDS). The proposed novel and innovative cyrocooler and the associated components enable high reliability and technical features that cannot be matched by conventional designs. The proposed cryocooler can also be a key component in next generationwireless communication systems and in cryogen management systems for space launch operations. Moreover, the proposed cryocooler can also enable portable systems for biomedical imaging (such as in MRI) and cryo-surgery so that they can be used in doctors'offices, thus revolutionizing some of the important medical procedures.