Small Turbo-Brayton Cryocoolers

The development of miniature turbomachinery has made possible the extension of the operating range of turbo-Brayton cryocoolers down to applications requiring as little as 1–5 watts of refrigeration at 4.2 to 70 K. This paper reviews the status of this technology and describes two cryocoolers presently under development at Creare: a 5 watt, 70 K cooler for space sensors, and a 0.6 1/hour helium liquefier for Magnetic Resonance Imaging systems. Cycle configuration trades are discussed and bounds on turbo-Brayton cycle cooling temperatures and capacities are presented. The design and performance of prototypical hardware is described.KeywordsHeat ExchangerPressure LossCentrifugal CompressorHeat LeakTurbine Inlet TemperatureThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.