Design and Test of the NIST/Lockheed Martin Miniature Pulse Tube Flight Cryocooler
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A two-stage miniature pulse tube (PT) cryocooler, designed for a Space Shuttle flight demonstration, was built and tested at Lockheed Martin Astronautics (LMA) at Denver, CO and the NIST Boulder Laboratory. The Miniature PT Flight Cryocooler (MPTFC) was designed to provide 0.15 W of cooling at 80 K with heat rejection at 275 K. It was developed as the smallest cryocooler of its kind for the purpose of demonstrating launch survivability and thermal performance in a zero-g environment. A prototype laboratory version was first built and tested to provide information on component sizing and flow rates for comparison to numerical models. The flight version was then fabricated as a Getaway Special (GAS) Payload. Cost containment and manned flight safety constraints limited the extent of the MPTFC development to achieve performance optimization. Nonetheless, it reached 87 K driven by a commercially available tactical compressor with a swept volume of 0.75 cc. The on-orbit cooling performance was not demonstrated because of low battery voltage resulting from failed primary batteries. The first off-state PT thermal conductance measurements were successful, however, and the MPTFC also demonstrated the robustness of PT cryocoolers by surviving pro-launch vibration testing, shipping, and the launch and landing of STS-90 with no measurable performance degradation.
The design and performance optimization approach for miniature two-stage PT coolers are discussed. Some factors that may limit performance in small-scale PT coolers are identified also. Laboratory pre-launch and post flight performance data of the MPTFC are presented, including cooling performance as a function of heat load and rejection temperature. Off-state conductance results are discussed in a related but separate presentation.
The Miniature Pulse Tube Flight Cryocooler (MPTFC) flew as a NASA shuttle payload (GAS-197) in April 1998 aboard STS-90 (Shuttle Transportation System-90) as a technology demonstration experiment. The primary objectives of this experiment were to demonstrate pulse tube (PT) cryocooler performance and “off-state” thermal conductance in a micro-gravity environment and to verify launch survivability of miniature coolers having limited vibration mitigation features. This project was a collaboration between Lockheed Martin Astronautics (LMA) and the National Institute of Standards and Technology (NIST). Because of the STS schedule and the safety issues associated with manned space missions, the experiment was subject to a number of design constraints. The tight development schedule was based on limited flight opportunities preceding the construction of the International Space Station (ISS) and on a low project budget. These two constraints dictated the extensive use of commercially available components, including a tactical compressor and drive electronics (to obviate a long-life flight compressor development effort), an inexpensive electromagnetic latching valve, a commercial data acquisition system, and numerous commercial electronics components. Attention to flight safety issues directly impacted the MPTFC design in terms of operating pressure, sizing for limited battery-powered operation in a cold environment, and limited design opportunity for performance optimization. The overall flight experiment design also had to address various flight hazard issues, such as mechanical and electrical integrity, EMI, redundant fusing, diode isolation, mitigation for high temperatures, etc. The experiment design had to accommodate operation over a range of STS bay temperatures from −50 to +40°C. In addition, the experiment timeline had to conform to limited STS crew operations.
The approach for completing the project on schedule was to design and test a prototype cryocooler in parallel with the overall flight hardware system definition and parts procurement. Subsequently, the flight hardware and flight cryocooler development and testing were also accomplished as parallel efforts. Lockheed Martin had primary responsibility for the flight and GSE hardware and electronics, systems engineering, and for payload management, while NIST had primary responsibility for the cryocooler development, assembly, and testing. In practice each organization contributed to all of these tasks.
KeywordsPulse Tube Pulse Tube Refrigerator Drive Electronic Kennedy Space Center Tactical Compressor
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- 1.S. Zhu, P. Wu, and Z. Chen, “Double inlet pulse tube refrigerators: An important improvement,” Cryogenics 30, 514 (1990).Google Scholar
- 2.P.J. Storch, R. Radebaugh, and J.E. Zimmerman, “Analytical Model for the Refrigeration Power of the Orifice Pulse Tube Refrigerator,” NIST Technical Note 1343 (1990).Google Scholar
- 3.Gary, J., Daney, D.E., and Radebaugh, R., “A computational model for a regenerator,” Proc. Third Cryocooler Conference, NIST Special Publication 698, (1985), p. 199.Google Scholar
- 4.Gary, J. and Radebaugh, R., “An improved numerical model for calculation of regenerator performance (REGEN3.1),” Proc. Fourth Interagency Meeting on Cryocoolers, David Taylor Research Center, Report DTRC-91/003, (1991), p. 165.Google Scholar
- 5.J. H. Xiao, “Thermoacoustic theory for regenerative cryocoolers: A case study for a pulse tube refrigerator,” Proc. 7th International Cryocooler Conference, Air Force Report PL-CP-93-1001, Kirtland Air Force Base. NM (1993), p. 305.Google Scholar
- 6.J. H. Xiao, “Thermoacoustic heat transportation and energy transformation, Part 1: Formulation of the problem,” Cryogenics 35, 15 (1995).Google Scholar
- 7.J. H. Xiao, “Thermoacoustic heat transportation and energy transformation. Part 2: Isothermal wall thermoacoustic effects,” Cryogenics 35, 21 (1995).Google Scholar
- 8.J. H. Xiao, “Thermoacoustic heat transportation and energy transformation, Part 3: Adiabatic wall thermoacoustic effects,” Cryogenics 35, 27 (1995).Google Scholar
- 9.D. R. Ladner, P. Bradley, and R. Radebaugh, “Offstate Conductance Measurements of the NIST/Lockheed Martin Miniature Pulse Tube Flight Cryocooler: Laboratory vs. Space,” Cryocoolers 11, Plenum Publishers, NY (2001).Google Scholar