Noshiro Rocket Testing Center

Hiroaki Kobayashi

  (小林 弘明)

Profile Information

Affiliation
Professor, Institute of Space and Astronautical Science, JAXA
Degree
工学博士(東京大学)

J-GLOBAL ID
200901061542880861
researchmap Member ID
5000019456

Education

 1

Papers

 168
  • Yuki Sakamoto, Hiroaki Kobayashi, Yoshihiro Naruo, Yuichiro Takesaki, Tetsuya Sato
    Cryogenics, 131 103652-103652, Apr, 2023  
  • Shinsaku Imagawa, Akifumi Iwamoto, Shinji Hamaguchi, Yasuyuki Shirai, Rikako Kawasaki, Hikaru Oya, Fumiya Matsumoto, Masahiro Shiotsu, Makoto Tsuda, Yoh Nagasaki, Tsuyoshi Yagai, Hiroaki Kobayashi
    IEEE Transactions on Applied Superconductivity, 32(6) 1-5, 2022  Peer-reviewed
    The critical heat flux in liquid hydrogen is ten times higher than that in liquid helium and is approximately half of that in liquid nitrogen. Since the resistivity of pure metal such as copper or silver at 20 K is less than one-hundredth of that at 300 K, HTS magnets immersed in liquid hydrogen are expected to satisfy the fully cyostable condition or to be stable against high resistive heat generation enough for quench detection at a practical current density. In order to examine cryostability of HTS magnets in liquid hydrogen, a pool-cooled Bi2223 magnet with a 5 T magnetic field at 20 K has been designed, fabricated and tested in liquid nitrogen prior to excitation tests in liquid hydrogen. The magnet consists of six outer double pancake coils with the inner diameter of 0.20 m and four inner double pancake coils with the outer diameter of 0.16 m. The resistive voltage to initiate thermal runaway in the coil as-sembly in liquid nitrogen was higher than 1 V that is sufficient high for quench detection.
  • 近藤奨一郎, 杵淵紀世志, Richardson Mathew, 坂本勇樹, 小林弘明
    日本航空宇宙学会論文集, 70(4), 2022  
  • 杵淵紀世志, 杵淵紀世志, 更江渉, 小林弘明, 梅村悠, 杉森大造, 藪崎大輔, 藤田猛, 沖田耕一, 西村真二, 石川佳太郎, 北山治, 姫野武洋, 佐藤哲也
    日本航空宇宙学会誌, 70(7), 2022  
  • Matthew Richardson, Hiroaki Kobayashi, Yuki Sakamoto, Yusuke Maru, Shinichiro Tokudome, Satoshi Nonaka, Shujiro Sawai, Akira Oyama, Daisaku Masaki, Satoshi Takada, Hiromitsu Kakudo, Toru Kaga, Kiyoshi Kinefuchi, Tetsuya Sato
    ASCEND 2021, Nov 15, 2021  

Misc.

 167

Presentations

 64
  • MARU Yusuke, TAKESAKI Yuichiro, KOBAYASHI Hiroaki, NARUO Yoshihiro, KAWAI Tsutomu
    The Proceedings of Mechanical Engineering Congress, Japan, 2018
    <p>A loading system plays a role of loading and unloading liquid hydrogen between a carrier ship and a ground storage facility in hydrogen supply chain in which hydrogen in the form of liquid phase is transported by the carrier ship from a resource-rich country to a consuming country. An emergency release system (ERS), which is one of components of the loading system, is installed in the middle of transfer pipe of the loading system, and has function of separating and plugging the pipe at an abnormality during loading so as to prevent a large amount of cryogenic fluid from scattering. We have conducted R & D study of the ERS for liquid hydrogen based on an existing one for liquid natural gas (LNG). Whole system function of the ERS including separation behavior was verified conducting a field experiment with the ERS test model and liquid hydrogen. Through several tests, the separation mechanism and behavior were verified, and also, soundness of the seal mechanism was evaluated. While, auto-ignition phenomena were observed on the separation surface of the ERS after the separation, of which causes have not been identified yet. Characteristics of dispersion behavior of hydrogen that was released at the separation could be investigated measuring distribution of temperature and hydrogen concentration around the ERS test model.</p>
  • KOBAYASHI Hiroaki, TAKESAKI Yuichiro, NARUO Yoshihiro, MARU Yusuke, TSUJIGAMI Hiroshi, MIYANABE Kota, KAWAMURA Satoru, DAIMON Yu, UMEMURA Yutaka, MUTO Daiki
    The Proceedings of Mechanical Engineering Congress, Japan, 2018
    <p>To improve safety regulations for fuel cell vehicles and hydrogen infrastructure, experiments of cryo-compressed hydrogen leakage diffusion were conducted. The experimental apparatus can supply 90 MPa hydrogen of various temperature conditions. Measurement items were hydrogen concentration distribution, blast pressure, flame length, and radiant heat. In addition, high speed camera observation was carried out to investigate the near-field of cryogenic hydrogen jet at supercritical pressure. The experimental apparatus can supply 90 MPa hydrogen at various temperature conditions (50 K–300 K) at a maximum flow rate of 100 kg/h. The hydrogen leakage flow rate was measured using pinhole nozzles with different outlet diameters (0.2 mm, 0.4 mm, 0.7 mm, and 1 mm). It was confirmed that the hydrogen leakage flow rate increases as the supply temperature decreases. The hydrogen concentration distribution was measured by injecting high-pressure hydrogen from the 0.2-mm pinhole for 10 min under a constant pressure/temperature condition. As the hydrogen injection temperature decreased, it was found that the hydrogen concentration increased, and an empirical formula of the 1% concentration distance for the cryogenic hydrogen system was newly presented.</p>
  • 坂本 勇樹, PEVERONI Laura, 小林 弘明, 箕手 一眞, 多根 翔平, 佐藤 哲也, VETRANO Rosaria
    日本冷凍空調学会年次大会講演論文集 Proceedings of the JSRAE Annual Conference, 2017
  • MARU Yusuke, TAKESAKI Yuichiro, KOBAYASHI Hiroaki, DAIMON Yu, UMEMURA Yutaka, NARUO Yoshihiro, MATSUNO Yu
    The Proceedings of Mechanical Engineering Congress, Japan, 2017
  • KOBAYASHI Hiroaki, TAKESAKI Yuichiro, NARUO Yoshihiro, MATSUNO Yu, TSUJIGAMI Hiroshi, MIYANABE Kota, KAWAMURA Satoru, MARU Yusuke, DAIMON Yu, UMEMURA Yutaka
    The Proceedings of Mechanical Engineering Congress, Japan, 2017
    <p>JAXA has constructed an experimental facility to pressurize and supply liquid hydrogen at a maximum pressure of 90 MPa to conduct experimental research on the injection of high pressure liquid hydrogen into the atmosphere. Liquid hydrogen has a property that its density greatly changes depending on pressure despite being a liquid phase. In addition, the high pressure hydrogen gas is in a supercritical state and has an intermediate property between a gas and a liquid. Therefore, it is a difficult question whether to treat the injection of high pressure liquid hydrogen as a gas phase phenomena or as a liquid phase phenomena. As a result of the experiment, it was found good to apply the liquid orifice equation to predict the discharge flow rate of high pressure liquid hydrogen.</p>

Professional Memberships

 3

Research Projects

 13

Industrial Property Rights

 9