First Successful Space Demonstration of a Thermal Accumulator for Microsatellites

Research Press Release | December 01, 2014

  • HODOYOSHI 4 and the Heat Storage Device: The accumulator and reference surface differ in that the former includes a heat storage medium, while the latter does not. The material of the surface, and the surface treatment, are the same. A comparison of the temperatures of the reference surface and accumulator confirms that the accumulator stores and releases heat.
    HODOYOSHI 4 and the Heat Storage Device: The accumulator and reference surface differ in that the former includes a heat storage medium, while the latter does not. The material of the surface, and the surface treatment, are the same. A comparison of the temperatures of the reference surface and accumulator confirms that the accumulator stores and releases heat.
  • Orbital Test Results:  The blue lines indicate the temperature of the reference surface, the orange points indicate the accumulator temperature, and the yellow lines indicate the amount of power generated by the solar panels. Generation of zero power by the solar panels indicates that Hodoyoshi 4 is in the earth’s shadow. Generation of any amount of power above zero indicates that Hodoyoshi 4 is in sunlight. As Hodoyoshi 4 emerges from the earth’s shadow, it is increasingly exposed to sunlight, and temperatures of the reference surface and accumulator increase. At approximately 90°C, the accumulator temperature (orange points) becomes less than the reference surface temperature (blue lines). The accumulator stores heat (i.e. absorbs heat) in this region, preventing an increase in temperature. Hodoyoshi 4 then moves into the earth’s shadow, and the temperatures of the reference surface and accumulator decrease. It is thus apparent that when the temperature drops to below 10°C, the temperature of the accumulator (orange points) becomes higher than the temperature of the reference surface. The accumulator releases heat in this region, thus preventing a drop in temperature.
    Orbital Test Results: The blue lines indicate the temperature of the reference surface, the orange points indicate the accumulator temperature, and the yellow lines indicate the amount of power generated by the solar panels. Generation of zero power by the solar panels indicates that Hodoyoshi 4 is in the earth’s shadow. Generation of any amount of power above zero indicates that Hodoyoshi 4 is in sunlight. As Hodoyoshi 4 emerges from the earth’s shadow, it is increasingly exposed to sunlight, and temperatures of the reference surface and accumulator increase. At approximately 90°C, the accumulator temperature (orange points) becomes less than the reference surface temperature (blue lines). The accumulator stores heat (i.e. absorbs heat) in this region, preventing an increase in temperature. Hodoyoshi 4 then moves into the earth’s shadow, and the temperatures of the reference surface and accumulator decrease. It is thus apparent that when the temperature drops to below 10°C, the temperature of the accumulator (orange points) becomes higher than the temperature of the reference surface. The accumulator releases heat in this region, thus preventing a drop in temperature.
Press Release
Key Points ・Performance of a thermal storage medium storing heat through changes in crystal structure successfully demonstrated in space.
Overview

A group led by Associate Professor Tsuyoshi Totani of the Division of Mechanical and Space Engineering at the Hokkaido University’s Faculty of Engineering, and funded under last year’s Cabinet Office Advanced Research Support Program, is working on the development of a thermal accumulator for microsatellite applications. The thermal accumulator employs trans-1,4-polybutadiene, a compound characterized by accumulation of a large amount of heat upon changes in its crystal structure within the solid phase, rather than accumulation of heat upon change from the solid to liquid phase. Using it within the temperature range in which the crystal structure changes has the advantage of eliminating any requirement for a container for the accumulator.


The accumulator was launched on the microsatellite Hodoyoshi 4 on June 20th, and tested to verify performance in space environment. Analysis of the data received from Hodoyoshi 4 confirms that the accumulator stored and released heat in space at the predetermined temperature. These results are a world-first in the successful demonstration of a thermal accumulator using trans-1,4-polybutadiene. The accumulation of heat at the predetermined temperature absorbs heat produced by on-board equipment with the microsatellite, preventing overheating of on-board equipment. The ability of the accumulator to release heat at the predetermined temperature allows it to warm on-board equipment, thus maintaining it at predetermined temperature. This success is expected to accelerate the use of the accumulator in microsatellites with their severe weight restrictions.

Inquiries

Tsuyoshi Totani, Associate Professor, Laboratory of Space Systems, Division of Mechanical and Space Engineering, Faculty of Engineering, Hokkaido University

TEL & FAX: +81-11-706-7192

E-mail: tota@eng.hokudai.ac.jp

Japanese

Link

 超小型人工衛星用蓄熱器の宇宙実証にはじめて成功
Publications 日本機械学会 熱工学コンファレンス 2014 講演論文集 (2014.11.8)

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