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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

High Efficiency Megawatt Machine Rotating Cryocooler Conceptual Design

Some of the challenges associated with developing electric aircraft propulsion systems include developing powertrain components that are both efficient and light-weight. In particular, electric motors must simultaneously achieve high efficiency by minimizing electrical and mechanical losses while also achieving high specific power by increasing the torque and/or speed. Normally increasing torque or speed will increase electrical and mechanical losses. The High Efficiency Megawatt Machine (HEMM) minimizes electrical losses by incorporating a superconductor to enable increased current on the rotor. And the rotor spins in a vacuum to minimize thermal and mechanical losses. Some organizations have been developing superconducting rotors for similar reasons using either cryogenic fluid transfer systems, fully immersed cryogenic cooling, and in a few cases utilized built-in cryogenic cooling on the rotor using a Brayton or Stirling system but the implementation was too large or inefficient for effective motor integration. Instead, a new approach for cryogenically cooling the superconducting rotor coil with an embedded rotating cryocooler is presented that fits completely within the rotating shaft.

Dyson, Rodger W.↗
NASA NTRS2019

High Efficiency Megawatt Machine Rotating Cryocooler Conceptual Design

Some of the challenges associated with developing electric aircraft propulsion systems include developing powertrain components that are both efficient and light-weight. In particular, electric motors must simultaneously achieve high efficiency by minimizing electrical and mechanical losses while also achieving high specific power by increasing the torque and/or speed. Normally increasing torque or speed will increase electrical and mechanical losses. The High Efficiency Megawatt Machine (HEMM) minimizes electrical losses by incorporating a superconductor to enable increased current on the rotor. And the rotor spins in a vacuum to minimize thermal and mechanical losses. Some organizations have been developing superconducting rotors for similar reasons using either cryogenic fluid transfer systems, fully immersed cryogenic cooling, and in a few cases utilized built-in cryogenic cooling on the rotor using a Brayton or Stirling system but the implementation was too large or inefficient for effective motor integration. Instead, a new approach for cryogenically cooling the superconducting rotor coil with an embedded rotating cryocooler is presented that fits completely within the rotating shaft.

Dyson, Rodger W.↗
NASA NTRS2017

Characterization Testing of Lockheed Martin High-Power Micro Pulse Tube Cryocooler

This paper describes the thermal vacuum, microphonics, magnetics, and radiation testing and results of a Lockheed Martin high-power micro pulse tube cryocooler. The thermal performance of the microcooler was measured in vacuum for heat reject temperatures between 185 and 300 K. The cooler was driven with a Chroma 61602 AC power source for input powers ranging from 10 to 60 W and drive frequency between 115 and 140 Hz during thermal performance testing. The optimal drive frequency was dependent on both input power and heat reject temperature. In addition, the microphonics of the cooler were measured with the cooler driven by Iris Technologies LCCE-2 and HP-LCCE drive electronics for input powers ranging from 10 to 60 W and drive frequency between 135 and 145 Hz. The exported forces were strongly dependent on input power while only weakly dependent on the drive frequency. Moreover, the exported force in the compressor axis was minimized by closed loop control with the HP-LCCE. The cooler also survived a 500 krad radiation dose while being continuously operated with 30 W of input power at 220 K heat rejection temperature in vacuum. Finally, the DC and AC magnetic fields around the cooler were measured at various locations.

Rodriguez, Jose I.↗
NASA NTRS2018

Characterization Testing of Lockheed Martin Micro1-2 Cryocoolers Optimized for 220 K Environment

The Mapping Imaging Spectrometer for Europa (MISE) Instrument on the Europa Clipper mission has baselined a Lockheed Martin high-power Micro1-2 pulse tube cryocooler operating at 135 Hz with a 220 K heat rejection temperature. This paper describes the testing and results of two Lockheed Martin Micro1-2 coolers optimized for these conditions. The thermal performance of the microcoolers was measured in vacuum for heat reject temperatures between 220 and 230 K. The coolers were operated with input powers ranging from 5 W to 40 W and drive frequency between 125 Hz and 145 Hz. The optimal drive frequency was strongly dependent on heat reject temperature. In addition, the exported forces and torques of the coolers were measured at 300 K heat rejection for input powers ranging from 5 W to 60 W and drive frequency between 120 Hz and 160 Hz. The exported forces were dependent on both piston amplitude and drive frequency. Moreover, the following were measured on one of the coolers: DC and AC magnetic fields at various locations, the off-state conductance of the pulse tube, and the effect of inclination angle of the pulse tube relative to gravity on the performance of the cooler. Finally, one of the coolers was subjected to random vibration testing.

Rodriguez, J.I.↗
NASA NTRS2020

Characterization Testing of Space-Flight Lockheed Martin Micro1-2 Cryocooler for the Mapping Imaging Spectrometer for Europa (MISE)

The Mapping Imaging Spectrometer for Europa (MISE) instrument on the Europa Clipper mission uses a Lockheed Martin “high-power” Micro1-2 pulse tube cryocooler with a heat rejection temperature around 220 K to provide cooling at 80 K. This paper describes the thermal performance and exported forces characterization testing and results of the space-flight Lockheed Martin Micro1-2 cooler optimized for these conditions. Prior to these characterization tests, the cooler passed random vibration and thermal vacuum cycling at Lockheed Martin.

Rodriguez, Jose↗
NASA NTRSDate not supplied

Thermal Vacuum Chamber Demonstration of a Cryocooled, HTS Rotor for a 1.4 MW Electric Machine for Electrified Aircraft Propulsion

Aircraft with electrified propulsion systems require electric machines that are very lightweight and highly efficient. Advancements to the state of the art are required to meet this demand. This is particularly true for large transport aircraft with more than about 150 passengers, which will require electric machines with power ratings in the 1 to 30+ MW range. At this scale of power, superconducting technology becomes attractive for electrified aircraft propulsion to increase efficiency and reduce mass [1]. A mass reduction relative to non-superconducting machines can result from an increase in the specific power of the machine and indirectly through a significant reduction in the amount of waste heat generated on the aircraft, which reduces the mass of the thermal management system [2]. NASA’s high efficiency megawatt motor (HEMM) is a 1.4 MW partially superconducting machine that is being developed to achieve an efficiency greater than 98% and electromagnetic specific power greater than 16 kW/kg. HEMM contains a copper stator operating at an average temperature around 423 K and a superconducting rotor composed of no-insulation 2nd generation high temperature superconducting (HTS) coils that operates around 60 K. The superconducting coils are conductively cooled by a pulse tube cryocooler embedded inside and rotating with the rotor shaft. This paper presents a full-scale demonstration of the rotor in a thermal vacuum chamber at the designed operating temperature. The test was designed to validate the design of HEMM’s rotor, namely the ability to operate the 2G HTS coils at their rated direct current in a relevant thermal environment while being conductively cooled.

high temperature superconductors↗
NASA NTRS2021

The Effect of Transfer Line Length and Heat Rejection Temperature Distribution on the Thales Linear Pulse Tube (LPT) Cryocoolers

Four Thales LPT9310 and four Thales LPT9510 commercial off-the-shelf (COTS) cryocoolers were parametrically performance tested. The LPT9310 coolers had transfer lines of various lengths while the LPT9510 coolers all had the same transfer line geometry. The LPT9510 test results revealed unit-tounit thermodynamic performance variation, quantified the effect of compressor temperature on thermodynamic performance and quantified the heat flow distribution between the compressor and expander as a function of their temperature distribution. The LPT9310 test results revealed the optimal drive frequency as a function of transfer line length, quantified the effect of heat rejection temperature distribution on thermodynamic performance and enabled the development and verification of a thermodynamic performance prediction tool that accounted for cold tip temperature, heat lift, heat rejection temperature and transfer line length.

Rodriguez, J.I.↗
DOE OSTI2020

Cryocooled cold trap system for the SuperCDMS dilution refrigerator

Operating 6,800 feet underground at the SNOLAB facility in Sudbury, Ontario, Canada, the dilution refrigerator-cooled SuperCDMS SNOLAB (Super Cryogenic Dark Matter Search at the Sudbury Neutrino Observatory Laboratory) experiment has been designed for maximum cryogenic up-time and remote operations. A key element in achieving these goals is a pair cold traps in the helium circulation stream of the dilution refrigerator; the first operating near liquid nitrogen temperatures and the second operating near liquid helium temperatures. Previous experience with the CDMS experiment, located underground at the Soudan Under-ground Laboratory, has given significant operational experience with dilution refrigerator cold traps and has solidified the demand of a system of dual cold traps. Unlike the CDMS-era system, the new SuperCDMS system will feature a cryocooler powered liquid nitrogen re-liquefying system (as opposed to regular under-ground re-filling of cold trap dewars using portable nitrogen dewars) and a cryogen-free 4 K cold trap, which eliminates the need for a bath of liquid helium.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Rapid Cryogenic Electrical Characterization of Materials and Devices Using Gifford-McMahon Cryocoolers

Thin-film heterostructures are necessary building blocks for superconducting and phononic quantum computing devices. Many new generations of quantum hardware demand extensive materials research to optimize performances at cryogenic temperatures (below 10 K). Here, we demonstrate compact cryogenic measurement systems capable of reaching sub-10K temperatures in less than three hours with the ability to measure AC/DC resistance and dielectric properties of thin-film materials. Our platform utilizes Gifford-McMahon (GM) cryocoolers as effective tools for providing high throughput cooling-warming cycles. We successfully used the GM-based measurement systems to measure 1) the superconducting transition temperature for Nb thin films (T c ~7.8 K), and 2) the temperature dependence of the dielectric constant in SiO 2 thin films down to 10 K. The fast electrical characterization feedback will be critical in developing robust materials and components for cryogenic computing devices.

36 MATERIALS SCIENCE↗
NASA NTRS2002

Evaluation of hydride compressor elements for the Planck sorption cryocooler

Hydrogen sorption crycoolers are being developed for the European Space Agency Planck mission to provide nominal 19 K cooling to instruments for measuring the temperature anisotropy of the cosmic microwave background with extreme sensitivity and resolution.

sorption cryocoolers metal hydides gas gap heat sw↗