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第28回宇宙利用シンポジウム (2012年1月23-24日. 日本学術会議), 港区, 東京都, Space Utilization Research (January 23-24, 2012. Science Council of Japan), Minato-ku, Tokyo Japan, 著者人数: 11名, 資料番号: SA6000032038, レポート番号: M38

第27回宇宙利用シンポジウム (2011年1月24日-25日, 宇宙航空研究開発機構宇宙科学研究所相模原キャンパス), 相模原市, 神奈川県, The Twenty-seventh Space Utilization Symposium (January 24-25, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, Boiling heat transfer is one of promising means to be applied for the thermal management systems handling a large amount of heat in space. However, gravity effects on the two-phase flow phenomena and corresponding heat transfer characteristics have not been clarified in detail. Experiments on flow boiling heat transfer onboard "KIBO" in international space station were proposed to clarify the flow boiling heat transfer phenomena under microgravity connditions. Ground tests by using a Bread Board Model (BBM) were conducted to verify the performance of a heated test section., 著者人数: 13人, 形態: カラー図版あり, Number of authors: 13, Physical characteristics: Original contains color illustrations, 資料番号: AA0065129035

Boiling heat transfer enhancement is efficient for development of a cold plate used in a two-phase flow loop type thermal control system. This study deals with boiling heat transfer enhancement for a narrow channel by thermal spray coating. Copper particles were coated on the heating surface by vacuum plasma spraying. Two kinds of surface were manufactured using different particle size, about 200 and 50 micrometer. The heat transfer performance was evaluated in saturated flow boiling experiments of HCFC123 for ranges of mass flux of 100 to 400 kg m(exp -2) s(exp -1), inlet quality of 0 to 0.60, and heat flux of 25 to 251 kW/sq m. The test channel with the channel width of 20 mm, and heated length of 100 mm was placed horizontally and heated from the bottom by cartridge heaters through a copper block. The channel gap was set to 2 and 4 mm. As the result, the coating surface produced higher heat transfer coefficient than the smooth surface, especially, the heat transfer performance of the surface using finer particle was higher and was about five to 10 times higher than that of the smooth surface. While the effect of gaps on the heat transfer coefficient was a little, the critical heat flux increased with increasing the channel gap., 資料番号: AA0063706054

Experiments were performed to verify the performance of experimental apparatus for the acquisition of reference data for flow boiling heat transfer under the terrestrial condition which is to be compared with that obtained under the microgravity condition onboard International Space Station (ISS) by using another apparatus with the same specification. Test section is a circular tube made of copper with an inner diameter of 4 mm and a heated length of 368 mm and oriented vertically on ground. To improve the accuracy of local heat fluxes, the compensation of heat flux distribution along the tube axis is discussed on the basis of the experimental results on the local heat transfer coefficients for a single-phase liquid flow. Correlations for local heat transfer coefficient of flow boiling are proposed here as functions of boiling number and Martinelli parameter in the regions of nucleate boiling and two-phase forced convection, respectively. Because the discrepancy of local heat transfer coefficient obtained from the apparatus for the terrestrial and the space experiments is caused by the difference of surface roughness in nucleate boiling region, a compensation factor is introduced in the correlation. The local heat transfer coefficients predicted by the proposed correlation are agreed well with those obtained by both apparatus., 著者名の誤記: USUSKU, 形態: カラー図版あり, The Clerical error of an author's name: USUSKU, Physical characteristics: Original contains color illustrations, 資料番号: DS1540522000

In order to clarify flow behavior and heat transfer characteristics of flow boiling in microgravity, the boiling and two-phase flow experimental facility which will be conducted in International Space Station (ISS) is developed. The glass heated section as an evaporating test section is installed in this facility, and the heated section is consisted of three transparent heated tubes which have different heated length, 50 mm, 50 mm and 5 mm, respectively. The transparent heated tube is made by Pyrex glass and the inner wall of the tube is covered by extremely thin gold film as using not only a heater but also resistance thermometer; that is, the tube can be measured the averaged inner wall temperature of the entire heated area. In addition, gas-liquid behavior of flow boiling can be observed through the gold film. The transparent heated short tube, which has 5 mm heated length and 4 mm inner diameter is a newly developed for third segment of the heated section of ISS experiment. In this study, derivation of the inner wall temperature and image analysis of flow behavior by using the short tube is described. Then the relation between heat transfer characteristics and flow behavior by using this tube is discussed. As a result of single-phase heat transfer experiment, the electrode resistance of the heated tube should be considered for estimation of the inner wall temperature of the short tube. Nusselt number considered the resistance of the electrode part has a good agreement with existing correlations compeared to Nusselt number derived from total resistance of the tube. By using the image analysis, useful information such as liquid film thickness of annular flow and passing of disturbance wave can be obtained with heat transfer characteristics data simultaneously. The results indicates that the heat transfer in the liquid film region of slug flow is insignificantly small compeared to turbulent liquid flow at the wake of slug under the conditions of this study., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540524000

Boiling and two-phase flow attract much attention for the improvement of cooling and heat dissipation processes on the ground and in space. However, there is very limited number of experimental data and no systematic or no coherent data needed for the design of space thermal management systems. In addition to establish the framework of database for boiling and two-phase flow in microgravity, the clarification of dominant force regime map is of top importance. Once the operating conditions free of gravity effect are clarified, reliable space systems can be developed by the iteration of ground tests. Furthermore, two-phase mixtures involving vapor phase can be transported independent of its orientation in the terrestrial cooling systems. Flow boiling experiments is planned onboard ISS by JAXA in 2016. In the present paper, individual subjects in the regimes of nucleate boiling and two-phase forced convection and the subjects in liquid-vapor interfacial behaviors are discussed by the citation of the results from the experiments of short microgravity duration, and the design concept of experimental setup under the restrictions inherent in the space experiment is described including the structures of test sections already integrated in PFM., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540519000

近年の宇宙構造物の大規模化に伴う排熱量増大や、宇宙太陽発電システム(SSPS)の各変換部の冷却など、宇宙における排熱技術に対するニーズは高まっており、潜熱利用流体ループ式排熱システムが注目されている。このシステムは蒸発潜熱を利用して熱を吸収し、輸送するため、ポンプ動力やシステム重量を軽減できるメリットがある。また、圧力により作動流体の飽和温度を制御できるため素早く正確な制御が可能であるが、その制御技術は未だ確立されておらず実用化に至っていない。本論文では、潜熱利用流体ループ式排熱システムの動特性の把握を目的に、熱負荷、作動流体流量などの各種パラメータ変化に対する動特性実験を行った。さらに、従来の研究に無い新しいバルブ操作による制御方式を提案する。次に、動特性実験と同時に、本システムの動的シミュレーションモデルを構築し数値解析を行い、実験結果と比較検討した。これらの実験・数値解析より、以下の結果が得られた。1)熱負荷変化に対する蒸発器表面温度変化の一次遅れ時定数は低クォリティ領域では作動流体のクォリティに左右され、サブクール沸騰領域で極端に時定数が大きく、遅い。2)作動流体流量を操作する事は、潜熱利用流体ループ式熱制御システムの熱源温度を制御する方法としては不適当である。3)アキュムレータ圧力変化に対する蒸発器表面温度変化の一次遅れ時定数は低クォリティ領域では作動流体のクォリティに左右され、サブクール沸騰領域で極端に時定数が大きくなる。4)バルブを操作する事でEV圧力およびEV表面温度は一次遅れ状に変化する事が確認できた。5)蒸気バルブ開度操作により、潜熱利用流体ループ式排熱システムの熱源温度を自動的に一定範囲に制御する事が可能である事が検証できた。6)数値解析結果は実験結果と良く一致し、潜熱利用流体ループ式排熱システムの動的シミュレーションヘの適用可能性が確認できた。, 資料番号: AA0047682000, レポート番号: JAXA-CR-04-001