From the minds at Technology Summary Turbo-Brayton Cryocoolers for High-Temperature Superconducting SystemsContact InformationDr. Tony Dietz Creare is a successful research and development company providing innovative solutions for16 Great Hollow Road over 50 years. We have a history of successful spin-offs and are currently forming a dedicatedHanover, NH 03755 turbo-Brayton cryocooler product company to seize significant High Temperature(603) 643-3800 Main Superconducting (HTS) systems opportunities in the Wind Energy Generation, Power(603) 640-2310 Direct Transmission, Data Center, and Naval Vessel firstname.lastname@example.org HTS systems are being developed to increase the efficiency and reduce the complexity in wind turbines and data center cooling as well as for a variety of military and aerospaceProduct applications. Today’s commercial cryocoolers (a key enabling component for deployment ofNext Gen Cryocoolers for HTS systems) are inadequate: they are heavy, large, noisy, and require regular maintenanceSuperconducting Systems Creare’s 1kw-class Turbo-Brayton cryocooler technology produces a system that is 7 timesProduct Benefits lighter, 5 times smaller, virtually silent, and uses ½ the energy to produce the same cooling7 times lighter of the best existing alternative, while providing a lifetime of maintenance free operation.5 times smaller This breakthrough technology is unparalleled and far surpasses alternative technologyMaintenance Free offered by competitors (Figure 2).Silent More than $50M of Government funds have been invested in Creares development of cryocooling technologies for NASA, DOD, and DOE applications. Turbo Cryogenics utilizes thisIndustries solid foundation to deploy commercial products in several fast-growing markets.Wind TurbinesElectric Grid AdvantagesData CentersNaval Vessels Best Competitor Turbo Cryogenics TC Benefit Cooling 1kW @ 50K 1kW @ 50K Same CoolingDevelopment Stage Units Needed 3 1 1 Unit>50M into Technology Input Power 47 kW 26 kW 1/2 the Power@Product Demo Phase Weight 800 kg 110 kg 7 Times Lighter Volume 1 m3 0.2 m3 5 Times Smaller Maintenance Every 10,000 hrs Never Maintenance Free Price >$300k <$250k 20% Cheaper Figure 1: It takes 3 Current Commercial Systems (Cryomech GM AL600 + Cryozone Circulator) to equal 1 Turbo Cryogenics unit.
From the minds atMarket Opportunity in High Temperature Superconducting SystemsHigh-temperature superconducting (HTS) materials have the potential to revolutionize the way we generate,transmit, and consume power. Transformational initiatives that rely on HTS technologies include: powerconditioning and power transmission systems, large-scale off-shore wind turbines, high-efficiency data centers, Navyship systems, and turbo-electric aircraft. The key advantages of superconducting systems are reductions in electricallosses, system size, system cost, and system weight (Figure 2). While cryocoolers are critical enabling components inany of these systems, current commercially-available cryocoolers are inadequate for these applications. Figure 2. Comparison of Generator Mass for a 10 MW Wind Turbine (courtesy of AML Clean Energy).The cooling system must maintain the superconducting elements at their required operating temperature, which istypically below 65 K. The conductor becomes resistive above this temperature, resulting in excessive heatingleading to a system failure known as quenching. This requirement for cooling can offset the advantages asuperconducting system offers over a warm copper system, because the cryocooler itself consumes power and addsweight and complexity. Therefore, to maximize the benefits offered by superconducting systems, the cryocoolermust be highly efficient, highly reliable, small size, low mass, and low-cost. Cryocoolers with these attributes are anecessary development that will enable the wide scale deployment of superconducting systems.Creare’s Turbo-Brayton CryocoolersCreare has developed turbo-Brayton cryocooler technology that is wellsuited to HTS applications. Our technology has its heritage in a space-qualified cryocooler that was developed by Creare and installed on theHubble Space Telescope. Our coolers rely on miniature turbomachinesoperating at high speeds in non-contract bearings that result in very longcomponent lives with no maintenance requirements. The components aresmall, light-weight, and may be configured in separate modules, facilitatingintegration into compact systems and allowing components to be situatedin thermally sensible locations, reducing parasitic heat loads and insulationrequirements. Distributed cooling is provided through the compressor-driven cycle gas, eliminating the need for an additional circulator and heatexchanger, and the machines may be multi-staged to provide cooling at Figure 3. Creare’s Turbo-Brayton Cryocoolermultiple temperatures. Furthermore, because the system relies on high- Installed on the Hubble Space Telescope inspeed turbomachines, the system efficiency and system mass scale 2002. It surpassed expectations and operated flawlessly for over six years.favorably at high capacities. This is not the case for competing regenerativecoolers, such as the Gifford-McMahon or Stirling systems that arecommercially available today.
From the minds atTurbo Cryogenics Competitive AdvantageCooling requirements for potential commercial HTS systems we have identified are in the range of hundreds ofwatts to several kilowatts at temperatures ranging from 15 K to 65 K, depending on the HTS wire technology and thespecific system design. The sweet spot seems to be a cooler that provides 1kW cooling at 50 K for systems usingYBCO superconductors, or 1 kW at 15 K for systems using MgB2 superconductors. System designers must consider atrade between these two temperatures because YBCO systems at 50 K require less cryocooler input power whileMgB2 conductors at 15 K are potentially less expensive. In either case, the system complexity, logistic support, andlife-cycle costs of a system cooled by a cryocooler are much better than a system cooled by liquid cryogens such asnitrogen and helium.Commercially-available cryocoolers are not well suited for these HTS applications. The required cooling capacity isabove the upper end of what is possible with regenerative cryocoolers such as Gifford-McMahon, Stirling, or PulseTube machines, which would require multiple machines chained together. Furthermore, commercially-availableregenerative cryocoolers do not have the reliability, durability and low-maintenance qualities that are required forthese applications. Finally, regenerative cryocoolers cannot provide the type of distributed cooling that is requiredfor an integrated HTS system and additional cryogenic circulators must be integrated – adding cost, complexity andreliability concerns.In the case study shown in Figure 1 above, we determined that a Turbo Cryogenics turbo-Brayton cryocooler wouldbe 86% less heavy, take up 80% less volume, consume 50% less power, have a much higher reliability and greatlylower maintenance requirements than a system built from commercially-available, Gifford-McMahon cryocoolers.Yet the initial cost of the Creare cooler would be similar, and the life-cycle cost would be much lower.The Brayton cooling cycle is the cycle of choice for large capacity cooling applications such as gas liquefaction andseparation. However, the capacity of cryocoolers developed for these applications is much greater than thatrequired for HTS applications. Air Liquide, a major international supplier of turbo-Brayton cryocoolers, recentlystarted development of a lower capacity system. However, the capacity of that system is still an order of magnitudegreater than the 1kW cooling power market niche we have identified for HTS applications.There is a real near-term market opportunity for turbo-Brayton cryocoolers providing 1 kW of cooling attemperatures suitable for high-temperature superconducting systems. Scaling up our space-qualified gas-bearingturbomachine technology will provide the best cryocooler product for this market. Additionally, as a US company,we have access to the defense market and funding for further technology development and applications.HTS Cryocooler Development and Production PlanWe have developed, matured, and fielded our cryocooler technology over the last two decades for low-volume,high-value applications leveraging over $50M of Government funding and we are ready to transition this technologyinto a higher volume commercial product. We plan to complete this transition through the three phase processillustrated in Figure 4.In the Technical Demonstration Phase, we will complete development of all system components and we willcomplete component performance testing. This Phase is in process now and is primarily being funded byGovernment Small Business Innovative Research (SBIR) funding. The funded projects include design and analysiswork and the fabrication and testing of a 50K, 1kW turboalternator. In the next phase, we plan to fabricate and testa representative engineering model of the cryocooler to demonstrate the integrated system and obtain systemperformance data. The final phase of the plan is the Manufacturing Development Phase, in which we will set up aproduction line for the cryocooler. This will entail design revisions to address issues identified during testing of theengineering model and design revisions to facilitate production. We will also fabricate or procure tooling and special
From the minds atequipment that will reduce the production unit cost. As we move down the production learning curve we expectunit costs to be very competitive with currently available cryogenic refrigerators for the same cooling load. Technical Demonstration Engineering Model Manufacturing Development Production Revision Component Tasks System Integration Tooling Fabrication Development Qualification Testing Production Line Setup Component Designs Product System Design Production Design Component Performance System Performance Data Production Line Data 2012/2013 2013/2014 2015 Figure 4. HTS Cryocooler Commercial Development Plan.Technology MaturityA functional diagram of a single-stage turbo-Brayton cryocooler cycle is shown in Figure 5. The cooling cycle iscontinuous flow and typically uses neon or helium gas, depending on the cooling temperature. At the warm end ofthe cycle, a centrifugal compressor pressurizes and circulates the cycle gas. The heat of compression and associatedinefficiencies of the compressor and electronics are rejected at the warm temperature. Recuperative heatexchangers (recuperators) are used to increase overall cycle efficiency by pre-cooling the high-pressure stream. Anexpansion turbine provides cooling through the load heat exchanger. This turbine also accommodates losses in therecuperator and parasitic heat loads at the cold end in addition to the cold load. Figure 5. Representative Components in the Turbo Brayton Cycle.
From the minds atCreare has the in-house knowledge and tools required to design each of the components in the system, as well asthe equipment and expertise needed to fabricate and test each of the components. Photos of representativecomponents that we have previously fabricated and tested are shown in Table 1. However, our previous systemdevelopment efforts and demonstrations were not always at the power level and temperature required forsuperconducting systems. Our space systems were sized for lower power levels, while the terrestrial systems wedeveloped were for higher temperatures. As a result, while our technology has been proven and our design toolsare mature, some development engineering remains before a cryocooler for industrial superconducting systems willbe ready for production. Table 1 below shows the relative states of development for each of the system’scomponents. We are moving toward completion of all component design, building, and testing to be ready forproduct deployment before the end of 2015. Table 1. Technology Development Plan for Components and Integrated System Component Maturity Risk Reduction Programs Status Navy Phase II SBIR funded to Testing of 1.3 kW prototype Turboalternator High demonstrate prototype. turboalternator in process. Navy Phase II SBIR option Low Compressor funded to demonstrate Design studies in process. prototype. NASA Phase I SBIR funded to Risk reduction trials about to Recuperator Medium conduct risk reduction trials begin. on new concept. Navy Phase II SBIR Option to Controls and High demonstrate bench top Pending funding. Instrumentation cryocooler. Pending funding. Preparing Integrated Engineering model Low proposal to ARPA-E FOA 670. System cryocooler demonstration. Matching funds required.Development Partners Creare is working with the Advanced Magnet Laboratory on the development of a 10 MW, fullysuperconducting wind turbine. AML (with Creare as part of the team) was recently selected as one of six companiesto be awarded $700K each in the first phase of a $50M DOE program to speed Atlantic offshore wind farmdevelopment. We are also working with AML on the optimization of superconducting systems for turboelectricaircraft in programs funded by NASA. In a separate project, we are working closely with scientists from the MITPlasma Science and Fusion Center to develop innovative concepts for connections and cables for superconductingpower systems. We have also teamed with MTECH and scientists from the Syracuse University Green Data Centeron an initiative to implement superconducting power transmission systems to improve the efficiency of datacenters. For military applications, we are working for the Navy Carderock Division to develop cryocoolers andsuperconducting systems for Navy ships, and for the Air Force Office of Scientific Research and the Air ForceResearch Laboratory to implement superconducting power transmission systems in military aircraft. Through thesepartners we are actively engaged in the development of future superconducting applications in addition to thecryocoolers required for these applications.
From the minds atIntellectual Property The primary intellectual property protection of our technology is in the form of trade secrets and, whereappropriate, United States patents. We have a small number of related patents awarded to date and we plan topursue further patents prior to production. Our past experience has shown that keeping inventions as trade secretsas long as possible can maximize the long-term return on the intellectual property provided by the limited term ofpatents. However, we realize the value and necessity of patents in the manufacturing industry, and will look toprotect certain manufacturing related products and processes for use in the spin-off company.Creare Background Creare was founded as an engineering service company in 1961. Our mission is to provide an optimumenvironment for creative engineers to perform technically excellent work that results in commercialized innovations.Over the last 50 years, we have grown into a company of approximately 130 people. Thirty percent of our staff areengineers, most of whom have advanced degrees. Our offices and laboratories cover over 60,000 sq. ft., with overhalf of the facility dedicated to laboratory and shop spaces. The laboratories are staffed with highly skilled electricaland mechanical technicians, machinists, and support staff who support a wide range of projects. The result is asuccessful company with a reputation for creating innovative solutions to the most challenging of engineeringproblems. Creare is committed to the commercialization of the technology we develop. Our commercializationapproach follows one of the three different paths shown in Figure 6: direct marketing as a custom Creare product,licensing technology, or the creation of spin-off firms. In total, these product firms and new ventures now generaterevenues of over $470 million per year and employ over 2,000 people.Figure 6: Creare’s Technology Commercialization. Creare has commercialized internally developed technology through sales ofcustom products, licensing agreements, and creation of independent spin-off firms.