Compact, Highly Reliable, Zero-Maintenance Cryocoolers for Submarine-Based High-Temperature Superconducting Systems

"The U.S. Navy requires a reliable, low-maintenance, long-life, vibration-free cryocooler to enable the use of High-Temperature Superconducting (HST) systems on submarines. The cryocooler must be integrated within an antenna mast or periscope imposingtight physical constraints on the cooler. Currently, no cryocooler exists that meets the unique requirements and constraints of this application. To meet these challenging requirements, we propose to develop an advanced turbomachine-based reverse-Braytoncryocooler (turbo-Brayton cryocooler). The cryocooler will incorporate high-speed, miniature turbomachines and high-performance, compact recuperators to attain excellent efficiency in a compact package. The critical design feature of the proposedturbo-Brayton cooler is the use of non-contacting, gas-film bearings in the miniature turbomachines. The bearings provide reliable, vibration-free, and maintenance-free operation. During Phase I, we will design the cooling system, define the interfaces,and demonstrate the operation of a key component, the miniature turbine, at the brassboard level. During Phase II, we will build a turbine optimized for this application, integrate the turbine in a brassboard turbo-Brayton cryocooler, and demonstrate theperformance of the cooling system at prototypical environmental and operating conditions. This program will result in the development of a turbo-Brayton cryocooler that exhibits zero vibration