An Advanced Compressor for High-Capacity Turbo-Brayton Cryocoolers

STSS and future DOD infrared sensor missions will require reliable, efficient and lightweight cryocoolers. A prior program at Creare resulted in the design of a two-stage turbo-Brayton cryocooler for load temperatures of 85 K and 35 K. The cryocooler is comparable in mass and efficiency with competing cryocooler technologies, and has the inherent benefits of negligible vibration emittance, ability to cool remote or distributed loads, and high reliability. The continuous flow nature of the turbo-Brayton cycle allows heat to be transported many meters from the cryocooler to thermal interfaces. In addition, the cryocooler can be configured with ultra-flexible tubes to provide heat transport from gimbal-mounted instruments without the use of two-phase heat transport systems or conductive straps. During the proposed program, we will continue with the development of a 35 K / 85 K turbo-Brayton cryocooler by demonstrating a high-capacity compressor. The other key components in the system-the turboalternators and recuperative heat exchangers-have been demonstrated or are under development. The successful development of the compressor is predicted to reduce cryocooler input power by 20 to 30%. During Phase I, we will evaluate improvements to existing compressor technology through analysis and compressor tests. During Phase II, we will build and test a high-capacity compressor at prototypical conditions.