SBIR-STTR Award

High-Temperature Superconducting (HTS) devices, needed for the modernization and expansion of America’s electricity delivery system, require efficient, reliable, and affordable cryogenic cooling of large cryostats. Commercial cryocoolers of appropriate capacity and temperature for transformers and cables miss the target on one or more of these parameters. This project will continue the development of a novel high-capacity cryocooler for transformer and cable applications (HTS-3 and HTS-4 applications). In recent demonstrations in small acoustic-Stirling cryocoolers, the new cryocooler exhibited high efficiency, reliability, and affordability. The cryocooler will be combined with a newly-invented, flexibly-attached remote coldhead, to provide practical cryostat integration at low cost. Phase I will adapt and upscale the remote coldhead innovation to make an acoustic-Stirling cryocooler of 300 watts capacity and a multi-head version of 900-1200 watts. This will be accomplished by using simulation codes to produce a detailed design and manufacturing process for the 300-watt (HTS-3) unit. Then, the resulting design and manufacturing process will be used along with cost data for related baseline coolers to verify feasibility, with a plan for hardware verification in Phase II.

Commercial Applications and Other Benefits as described by the awardee:
The new cryocooler should enable practical and reliable HTS power equipment, bringing economic, environmental, and enhanced security benefits to the electric power industry and its customers. In addition, the new cryocooler would be significantly superior (in efficiency, reliability, and practicality) to existing coolers now sold for medical and scientific imaging, gas recondensation or liquefaction, and large-scale cryopumping in vacuum-based manufacturing systems. The current world market for these cryocoolers is 2-3,000 units per year, with healthy growth expected

New approaches for practical cryogenic refrigeration are needed to realize the benefits of high-temperature superconductivity in the electrical power grid infrastructure. Current approaches do not provide sufficient reliability, efficiency, cost, and interface needed to support superconducting transformers, transmission lines, and other devices in commercial service. This project will combine the reliability and efficiency of acoustic-Stirling technology with the universality and adaptability of coldfinger interfaces to achieve capacities of direct usability in superconducting power systems. In Phase I, the mechanical design for new remote coldheads was completed, the production cost and reliability of coolers using that head were evaluated, and performance simulation models were executed. The models were validated by testing against an existing miniature remote-head cooler. It was determined that this cooler type can approach or meet the cost goal as well as the reliability, capacity, and efficiency required for superconducting power systems. Phase II will build and test the coolers designed in Phase I for superconducting transformers and transmission lines. One machine will be submitted for long-term testing. Commercial applications & Other Benefits as described by the awardee: The new coolers should deliver cold or liquid cryogen at less cost than traditional truck-and-store distribution (where applicable) and enable new uses where traditional distribution is unworkable (e.g., shipboard power electronics cooling). In addition to superconductivity, applications should include industrial gas liquefaction and recondensation, power electronics cooling, and general scientific cryogenics