A Passive, Adaptive and Autonomous Gas Gap Heat Switch

We report on the development of a heat switch for autonomous temperature control of electronic components in a satellite. A heat switch can modulate when needed between roles of a good thermal conductor and a good thermal insulator. Electronic boxes on a satellite should be maintained within a typical optimum temperature range of 260 to 310 K. The heat sinking is usually by means of a radiator. When the operating temperature of the electronic box increases beyond 310 K, a good contact to the radiator is desired for maximum cooling. On the other hand, when the satellite is in a cold dormant state, the electronics box should be heated by the onboard batteries. In this state a weak thermal contact is desired between the electronic box and the heat sink. In the present study, we are developing a gas gap heat switch in which the sorber material is thermally anchored to the electronic box. A temperature change of the electronic box triggers the (de-)sorption of gas from the sorber material and subsequently the gas pressure in the gas gap. This paper describes the physical principles and the current status of this technology. This approach can be extended to cryogenic temperature rang

300 mK CONTINUOUS COOLING, SORPTION-ADR SYSTEM

International audienc

Additive manufacturing of a compact flat-panel cryogenic gas-gap heat switch

State-of-the-art heat switches are only rarely employed in thermal system architectures, since they are rather bulky and have a limited thermal performance (expressed as the heat transfer ratio between the "On" and "Off" state). Using selective laser melting additive manufacturing technology, also known as 3D printing, we developed a compact flat-panel gas-gap heat switch that offers superior thermal performance, is simpler and more economic to produce and assemble, contains no moving parts, and is more reliable because it lacks welded joints. A prototype measuring 5×5×1 cm3 outer dimensions is developed with an integrated coolant heat sink to assess the feasibility of the technology. Later a second prototype measuring 3.2 mm thick, 10 cm by 10 cm frontal area panel is developed. An on-off heat conductance ratio of about 45 is measured at 100 K, and the on-conductance is 4.5 W/K. In addition to being compact, this type of heat switch has a large on-conductance compared to other types of cryogenic heat switches. This opens doors to utilize the heat switch for cryogenic temperature control applications. © 2016, International Institute of Refrigeration. All rights reserved

Performances of the 50mK ADR/sorption cooler

International audienceCEA/SBT is currently testing a 50 mK cooler developed in the framework of a European Space Agency Technological Research Program targeted for the Advanced Telescope for High Energy Astrophysics space mission. This cooler is composed of a small demagnetization refrigerator pre cooled by a sorption cooler stage. This Engineering Model is able to produce 1 lW of net heat lift at 50 mK and an additional 10 lW at 300 mK provided by the sorption cooler stage. The autonomy of the cooler is 24 h, and once the low temperature phase at 50 mK is over, it can be recycled in about 8 h with 10 lW and 100 lW available at respectively the 2.5 and 15 K heat sinks. These performances are in agreement with the European Space Agency requirements. In this paper, we present the detailed thermal performances of the cooler in nominal conditions as well as sensitivity measurements of the variation of the heat sink and the cold end temperatures

Progress in the Development of the IXO 50 mK Sorption-ADR stage

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.The nominal temperature of the new generations of detectors for the next space mission International X-ray Observatory (IXO) is expected to be around 50 mK. The coupling of a 3He cooler with an ADR provides an elegant cooler in this temperature range with low mass and few interfaces. As part of an ESA contract to develop such a solution, we designed an efficient assembly based on low thermal interfaces at 15 K and at 2.5 K. The cooler is sized to provide simultaneously net heat lifts of 1 μW at 50 mK and 10 μW at 300 mK for an autonomy exceeding 24 hours. The design of an engineering model is presented, as well as mechanical analysis and simulated results. The influence of the interface parameters are discussed together with different cycling scenario possibility