Large Capacity, Multi-Cylinder Cryocooler for High Temperature Superconductor (HTS) Applications

High Temperature Superconductor (HTS) devices ¿ which offer the promise of providing more efficient power transmission, generation, and use ¿ are emerging from the laboratory, and industry experts expect dramatic growth for the foreseeable future. While substantial investments have been made to develop both technology and markets for HTS devices, little attention has been paid to a critical enabling technology, namely, cryocoolers that can provide high efficiency, high capacity, high reliability, and long life with little or no maintenance requirements. This project will develop an innovative multi-cylinder cryocooler (MCC) that will address the needs of HTS devices in a cost effective manner and to a significantly higher degree than existing alternatives (such as pulse-tube cryocoolers or maintenance-intensive Gifford-McMahon cryocoolers). The design will benefit from parts that are interchangeable with Stirling engine components designed for low cost mass production. The MCC concept developed during Phase I integrates long-life, high reliability, maintenance-free flexure bearing, and clearance seal technology with the high capacity, double-acting alpha configuration of Stirling machine technology. Phase II will design and fabricate a functional prototype MCC that will be tested to prove the performance and benefits identified in Phase I. Commercial Applications and Other Benefits as described by the awardee: The multi-cylinder free-piston Stirling cryocooler should enable HTS technology to provide more efficient power distribution in densely populated communities, where a single HTS cable can replace several conventional cables. Another important application would enable more efficient naval vessels, in which conventional motors and generators could be replaced with HTS versions.