### Abstract

High-pressure hydrogen at a maximum of 100 MPa in a 1-L-volume vessel is discharged through 0.1-mm- and 0.2-mm-diameter orifices that imitate cracks, and the transient temperature and pressure behavior of the hydrogen in the vessel is presented. The hydrogen at the initial pressure of 100 MPa during its discharge through the ϕ 0.2-mm orifice reaches half of the initial pressure after 16 s, while it takes approximately nine times longer for the ϕ 0.1-mm orifice to reach half of the initial pressure. We theoretically calculate the transient temperature and pressure according to the fundamental equations based on the mass and energy conservations using an accurate equation of state for hydrogen. The actual flow rate through an orifice is generally smaller than the theoretically calculated flow rate because of the contraction flow. Therefore, in this study, we adopt the effective diameters of the orifices instead of the actual diameters, and from comparisons with the experimental pressure, we estimate them to be 0.6 and 0.9 of the actual diameters for the ϕ 0.1-mm and ϕ 0.2-mm orifices, respectively. We use a functional form with a time constant for the heat transfer coefficient to represent the transient temperature behavior, and we describe the time dependence of the heat transfer coefficient. The results show that the calculated temperature and pressure are in good agreement with the experimental values obtained.

Original language | English |
---|---|

Pages (from-to) | 17169-17174 |

Number of pages | 6 |

Journal | International Journal of Hydrogen Energy |

Volume | 41 |

Issue number | 38 |

DOIs | |

Publication status | Published - Oct 15 2016 |

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### All Science Journal Classification (ASJC) codes

- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Condensed Matter Physics
- Energy Engineering and Power Technology

### Cite this

*International Journal of Hydrogen Energy*,

*41*(38), 17169-17174. https://doi.org/10.1016/j.ijhydene.2016.06.114

**Transient temperature and pressure behavior of high-pressure 100 MPa hydrogen during discharge through orifices.** / Sakoda, Naoya; Onoue, Kiyoaki; Kuroki, T.; Shinzato, K.; Kohno, Masamichi; Monde, M.; Takata, Yasuyuki.

Research output: Contribution to journal › Article

*International Journal of Hydrogen Energy*, vol. 41, no. 38, pp. 17169-17174. https://doi.org/10.1016/j.ijhydene.2016.06.114

}

TY - JOUR

T1 - Transient temperature and pressure behavior of high-pressure 100 MPa hydrogen during discharge through orifices

AU - Sakoda, Naoya

AU - Onoue, Kiyoaki

AU - Kuroki, T.

AU - Shinzato, K.

AU - Kohno, Masamichi

AU - Monde, M.

AU - Takata, Yasuyuki

PY - 2016/10/15

Y1 - 2016/10/15

N2 - High-pressure hydrogen at a maximum of 100 MPa in a 1-L-volume vessel is discharged through 0.1-mm- and 0.2-mm-diameter orifices that imitate cracks, and the transient temperature and pressure behavior of the hydrogen in the vessel is presented. The hydrogen at the initial pressure of 100 MPa during its discharge through the ϕ 0.2-mm orifice reaches half of the initial pressure after 16 s, while it takes approximately nine times longer for the ϕ 0.1-mm orifice to reach half of the initial pressure. We theoretically calculate the transient temperature and pressure according to the fundamental equations based on the mass and energy conservations using an accurate equation of state for hydrogen. The actual flow rate through an orifice is generally smaller than the theoretically calculated flow rate because of the contraction flow. Therefore, in this study, we adopt the effective diameters of the orifices instead of the actual diameters, and from comparisons with the experimental pressure, we estimate them to be 0.6 and 0.9 of the actual diameters for the ϕ 0.1-mm and ϕ 0.2-mm orifices, respectively. We use a functional form with a time constant for the heat transfer coefficient to represent the transient temperature behavior, and we describe the time dependence of the heat transfer coefficient. The results show that the calculated temperature and pressure are in good agreement with the experimental values obtained.

AB - High-pressure hydrogen at a maximum of 100 MPa in a 1-L-volume vessel is discharged through 0.1-mm- and 0.2-mm-diameter orifices that imitate cracks, and the transient temperature and pressure behavior of the hydrogen in the vessel is presented. The hydrogen at the initial pressure of 100 MPa during its discharge through the ϕ 0.2-mm orifice reaches half of the initial pressure after 16 s, while it takes approximately nine times longer for the ϕ 0.1-mm orifice to reach half of the initial pressure. We theoretically calculate the transient temperature and pressure according to the fundamental equations based on the mass and energy conservations using an accurate equation of state for hydrogen. The actual flow rate through an orifice is generally smaller than the theoretically calculated flow rate because of the contraction flow. Therefore, in this study, we adopt the effective diameters of the orifices instead of the actual diameters, and from comparisons with the experimental pressure, we estimate them to be 0.6 and 0.9 of the actual diameters for the ϕ 0.1-mm and ϕ 0.2-mm orifices, respectively. We use a functional form with a time constant for the heat transfer coefficient to represent the transient temperature behavior, and we describe the time dependence of the heat transfer coefficient. The results show that the calculated temperature and pressure are in good agreement with the experimental values obtained.

UR - http://www.scopus.com/inward/record.url?scp=84995906247&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84995906247&partnerID=8YFLogxK

U2 - 10.1016/j.ijhydene.2016.06.114

DO - 10.1016/j.ijhydene.2016.06.114

M3 - Article

AN - SCOPUS:84995906247

VL - 41

SP - 17169

EP - 17174

JO - International Journal of Hydrogen Energy

JF - International Journal of Hydrogen Energy

SN - 0360-3199

IS - 38

ER -