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Compact Cryocooler for Maritime Operations


RT&L FOCUS AREA(S): Directed energy

TECHNOLOGY AREA(S): Ground / Sea Vehicles

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a scalable, compact, high-efficiency, low-cost, cryocooler capable of operations in maritime environments.

DESCRIPTION: Superconductivity is a unique state of matter, where at cryogenic temperatures a material has near zero resistance allowing a large current to pass through a relatively small wire. The ability to pass large currents through the wire enable it to be used for magnetic applications. Two temperature ranges of superconducting materials exist as low temperature superconductors (LTS) and high temperature superconductors (HTS). HTS materials begin to transition from a resistive to zero resistance superconducting state around 100 K, while LTS transition begins at much colder temperatures typically below 15 K. The exact transition temperature is material specific; however, regardless of material, superconductive systems require cryogenic environments. The elevated operating temperature of HTS makes the cryogenic cooling systems orders of magnitude more efficient than LTS.

The Navy plans to use HTS in several application including degaussing operations of large surface combatant ships. These systems require large cryocoolers and are less sensitive to the impacts of cryocooler size, weight, and efficiency than tactical applications. As the Navy explores future smaller-scale applications, there are commensurate requirements for novel compact cooling solutions. One such area is the Navy's development of superconducting magnets on the order of 6" to 24" diameter that will require cooling to cryogenic temperatures between 20-50 K with 40-80 W of available cryogenic cooling power. These magnets can serve a multitude of different applications and may be subject to varied operational environments.

Currently, commercial cryocooler technologies exist that can provide cooling on the order of 20 W at 60 K within a total system volume of 320 in3 and mass of 6.4 kg. Configuration of these coolers allows the entire cryocooler package to fit in a 5" diameter envelope. In addition to being small profile, these coolers boast a mean time to failure (MTTF) of 120,000 hrs, giving them excellent long-term reliability. Prior Navy developments targeted large-scale applications of superconductivity requiring cryocooling solutions from 300 to 700 W at 50 K, with targeted efficiencies of 30% of Carnot. Currently there is an order of magnitude gap in cooling capacity between COTS technology and the Navy-developed technology that attains high levels of efficiency.

The Navy is seeking technical solutions that can provide scalability to bridge the gap between the existing cryocooler technologies and the anticipated requirements to field future systems. The Navy anticipates several environmental constraints that will be imposed on the cryocooling technology including various mounting angles, changes in gravitational orientation due to platform roll and pitch, large shock forces, and operation in a high magnetic field environment, on the order of 2 T. Consequentially, any fully realized product needs to pass military shock requirements as listed in MIL-S-901D Grade A and military vibration standards established in MIL-STD-167-lA. Any product also needs to function independently of gravitational orientation (full 360 degrees, six degrees of freedom) and in the presence of magnetic fields approaching 2T. A viable solution must also be capable of operation with a range of cooling water temperatures from 4°C to 40°C. The solution should be less than 350 in3 total volume while fitting within a 6 in diameter container, weigh less than 6 kg and possesses the ability to operate where input power availability maybe greatly diminished. Therefore, designed efficiency targets should be greater than 25% of Carnot. The technical solution should include flexibility to be designed around input power that may include DC (12V, 24V, 48V), or AC (single-phase 120 V, or three-phase 440 V). The technical solution should target approximately 100 W (±20 W) of cooling at 50 K validated by experimental testing, which will include the injection of heat and temperature recording of the cryogenic space.

PHASE I: Develop a concept and complete a feasibility analysis of the cryocooler concept to meet desired performance specifications detailed in the Description. Design and manufacturing concepts should be assessed through modeling, analysis, and benchtop testing. Size, weight, nominal performance at design as well as capacity map from no-load to 300 K, and input power shall be documented. Perform a cost estimate for both prototype development and full-scale production. The Phase I Option, if exercised, includes a detailed design and specifications to build a prototype during a Phase II effort.

PHASE II: Develop, design, and fabricate a functional prototype of a compact cryocooler based on the results of the Phase I and Phase II Statement of Work (SOW) and complete characterization testing of key performance parameters at the proposer's facility or other suitable test center identified by the proposer. The designed capacity map developed in Phase I shall be updated and experimentally validated through testing of the initial prototype. Deliver the prototype to the Navy for further testing, along with maintenance and integration relevant designs and drawings. Test results, lessons learn, and design update recommendations derived from lessons learned during prototype testing shall be integrated into an additional prototype unit.

PHASE III DUAL USE APPLICATIONS: Aid in the transitioning of the technology for Navy use, as well as engage in market research, analysis, and scouting of potential industry partners to stand up production level manufacturing capabilities and facilities. The final product will be tested and verified for Navy use through the completion of qualification according to the relevant military specification and standard documents. This technology has value in any compact cryogenic application, including; to portable magnetic resonance imaging (MRI) systems, superconducting magnetic energy storage (SMES), and a wide variety of other applications, both commercial and military.


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  2. Fitzpatrick, B.K.; Golda, E.M. and Kephart, J.T. "High Temperature Superconducting Degaussing–Cooling Two HTS Coils With One Cryocooler for the Littoral Combat Ship." AIP Conference Proceedings, vol. 985, pp. 277-283, 2008/03/16.  
  3. “Datasheet: Cryotel DS 30.” Sunpower- Ametek, 2020.  
  4. “MIL-S-901D Grade A, Military Specifications: Shock Tests H.I. (High-Impact) Shipboard Machinery Equipment, and Systems, Requirements for.”  
  5. “MIL-STD-167-1A, Department of Defense Test Method Standard: Mechanical Vibrations of Shipboard Equipment.”
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