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International Journal of Hydrogen Energy

Advances in Pulsed and Continuous Detonation, 2019

The development of computational §uid dynamics (CFD) model to simulate blast wave and ¦reball dyn... more The development of computational §uid dynamics (CFD) model to simulate blast wave and ¦reball dynamics after high-pressure hydrogen tank rupture in a ¦re is described. Parametric study is performed to de¦ne the e¨ect of submodels, numerical methods, and parameters on the convergence of the simulations and reproduction of experimental data. Experiments with initial pressure in hydrogen tank of 350 and 700 bar were used to validate the model. The e¨ect of hydrogen combustion and tank opening on the blast wave strength is assessed. The simulated cases include instantaneous tank opening and half tank opening.

International Journal of Hydrogen Energy

Hydrogen, Nov 7, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Health and Safety Executive, 2020

Hydrogen storage is now, and will continue to be a key topic for established and developing appli... more Hydrogen storage is now, and will continue to be a key topic for established and developing applications moving forward. The main priorities identified for hydrogen storage are: 1 st priority: tank fire resistance (previously identified as a priority in 2016). 2 nd priority: non-destructive testing techniques for manufacturing and regular inspection. 3 rd priority: understanding the effects of tank overheating on the structural performance and lifetime of the tank (also highlighted as a key priority by session chair to underpin refuelling protocols). (4) Key Session Topic: ACCIDENT PHYSICS of GASEOUS HYDROGEN For the accident physics of gaseous hydrogen the top three priorities from a list of five are: 1 st priority: premixed combustion associated with large scale problems with obstacles, flame acceleration and particularly deflagration-detonation-transition (DDT). 2 nd priority: hydrogen venting. 3 rd priority: ignition statistical approaches and spontaneous ignition. These priorities are key to growing application inventories and preventing and understanding the consequences of accidental releases in these new and developing scenarios. (5) Key Session Topic: ACCIDENT PHYSICS of LIQUID HYDROGEN For the accident physics of liquid hydrogen the top three priorities from an extensive list of 15 are: 1 st priority: multi-phase accumulations with explosion potential. 2 nd priority: combustion properties of cold gas clouds, especially in congested areas. 3 rd priority: knowledge and experience related to releases of large quantities. Obviously, this is an highly important area with a number of outstanding issues, many of which are beginning to be addressed by international efforts, such as the FCH JU project PRESLHY or the Norwegian project SH2IFT. These efforts are essential, as LH2 is key to a number of applications, as noted with the strong overlap in priorities with aerospace and maritime, and others that will need larger hydrogen inventories and corresponding scaling-up of supply infrastructure. (6) Key Session Topic: MATERIALS The rapid development and deployment of hydrogen applications leads to an expectation that the materials that enable the novel use of hydrogen today must become the normal, common place and safe materials (or their equivalents) for tomorrow. To meet this expectation, it is essential that the characteristics and long term performance and reliability of materials across all applications is understood, evidenced, catalogued and applied. With this in mind, the materials prioritisation exercise is divided into two sub-chapters, as it was in 2016.

Fuel cell vehicles store hydrogen onboard at pressure either 70 MPa (bikes, cars and tracks) or 3... more Fuel cell vehicles store hydrogen onboard at pressure either 70 MPa (bikes, cars and tracks) or 35 MPa (buses). Tank volume is 10-140 litres. More than 1/3 of CNG car tank ruptures in a fire are due to pressure relief device failure. The quantitative risk assessment of hydrogen onboard storage [1] has demonstrated that the acceptable level of risk 10 fatalities/vehicle/year can be achieved if storage tank has fire resistance rating above 47 min. This is based on the non-zero probability of thermally activated pressure relief device (TPRD) failure. The consequences of tank rupture in a fire are blast wave, fireball, projectiles. To underpin hydrogen safety engineering the underlying physical phenomena should be understood first. The aim of this study is to understand if there is a contribution of combustion into the blast wave strength.

International Journal of Hydrogen Energy

Jet flames originated by cryo-compressed ignited hydrogen releases can cause life-threatening con... more Jet flames originated by cryo-compressed ignited hydrogen releases can cause life-threatening conditions in their surroundings. Validated models are needed to accurately predict thermal hazards from a jet fire. Numerical simulations of cryogenic hydrogen flow in the release pipe are performed to assess the effect of heat transfer through the pipe walls on jet parameters. Notional nozzle exit diameter is calculated based on the simulated real nozzle parameters and used in CFD simulations as a boundary condition to model jet fires. The CFD model was previously validated against experiments with vertical cryogenic hydrogen jet fires with release pressures up to 0.5 MPa (abs), release diameter 1.25 mm and temperatures as low as 50 K. This study validates the CFD model in a wider domain of experimental release conditions - horizontal cryogenic jets at exhaust pipe temperature 80 K, pressure up to 2 MPa ab and release diameters up to 4 mm. Simulation results are compared against such experimentally measured parameters as hydrogen mass flow rate, flame length and radiative heat flux at different locations from the jet fire. The CFD model reproduces experiments with reasonable for engineering applications accuracy. Jet fire hazard distances established using three different criteria - temperature, thermal radiation and thermal dose - are compared and discussed based on CFD simulation results.

Hydrogen Knowledge Centre, Sep 6, 2018

Advances in Pulsed and Continuous Detonation, 2019

Energies, 2021

This work focuses on the experimental and numerical investigation of maximum overpressure and pre... more This work focuses on the experimental and numerical investigation of maximum overpressure and pressure dynamics during ignited hydrogen releases in a storage enclosure, e.g., in marine vessel or rail carriage, with limited vent size area, i.e., the pressure peaking phenomenon (PPP) revealed theoretically at Ulster University in 2010. The CFD model previously validated against small scale experiments in a 1 m3 enclosure is employed here to simulate real-scale tests performed by the University of South-Eastern Norway (USN) in a chamber with a volume of 15 m3. The numerical study compares two approaches on how to model the ignited hydrogen release conditions for under-expanded jets: (1) notional nozzle concept model with inflow boundary condition, and (2) volumetric source model in the governing conservation equations. For the test with storage pressure of 11.78 MPa, both approaches reproduce the experimental pressure dynamics and the pressure peak with a maximum 3% deviation. However,...

Engineering tools for calculation of hazard distances for cryogenic hydrogen jets are currently m... more Engineering tools for calculation of hazard distances for cryogenic hydrogen jets are currently missing. This study aims at the development of validated correlations for calculation of hazard distances for cryogenic unignited releases and jet fires. The experiments performed by Sandia National Laboratories (SNL) on jets from storage temperature in the range 46-295 K and pressure up to 6 bar abs are used to expand the validation domain of the correlations. The Ulster’s under-expanded jet theory is applied to calculate parameters at the real nozzle exit. The similarity law for concentration decay in momentum-dominated jets is shown to be capable to reproduce experimental data of SNL on 9 unignited cryogenic releases. The accuracy of the similarity law to predict experimentally measured axial concentration decay improves with the increase of the release diameter. This is thought due to decrease of the effect of friction and minor losses for large release orifices. The dimensionless fla...

Liquid hydrogen (LH2) compared to compressed gaseous hydrogen offers advantages for large scale t... more Liquid hydrogen (LH2) compared to compressed gaseous hydrogen offers advantages for large scale transport and storage of hydrogen with higher densities and potentially better safety performance. Although the gas industry has good experience with LH2 only little experience is available for the new applications of LH2 as an energy carrier. Therefore, the European FCH JU funded project PRESLHY conducts pre-normative research for the safe use of cryogenic LH2 in non-industrial settings. The work program consists of a preparatory phase, where the state of the art before the project has been summarized and where the experimental planning was adjusted to the outcome of a research priorities workshop. The central part of the project consists of 3 phenomena oriented work packages addressing Release, Ignition and Combustion with analytical approaches, experiments and simulations. The results shall improve the general understanding of the behavior of LH2 in accidents and thereby enhance the state-of-the-art, what will be reflected in appropriate recommendations for development or revision of specific international standards. The paper presents the status of the project at the middle of its terms.

International Journal of Hydrogen Energy, 2020

Sol-Gel zirconium-n-butoxide(ZNB) yttrium nitrate yttria-stabilized zirconia(YSZ). ZNB yttria! "#... more Sol-Gel zirconium-n-butoxide(ZNB) yttrium nitrate yttria-stabilized zirconia(YSZ). ZNB yttria! "# YSZ %& '()*+' ,-. /0. 100 o C1 2 34 56 7%&89:;, 400 o C1 <=%& %> ?@ A9.

International Journal of Hydrogen Energy, 2019

Thermal hazards from an under-expanded (900 bar) hydrogen jet fire have been numerically investig... more Thermal hazards from an under-expanded (900 bar) hydrogen jet fire have been numerically investigated. The simulation results have been compared with the flame length and radiative heat flux measured for the horizontal jet fire experiment conducted at INERIS. The release blowdown characteristics have been modelled using the volumetric source as an expanded implementation of the notional nozzle concept. The CFD study employs the realizable κ-ε model for turbulence and the Eddy Dissipation Concept for combustion. Radiation has been taken into account through the Discrete Ordinates (DO) model. The results demonstrated good agreement with the experimental flame length. Performance of the model shall be improved to reproduce the radiative properties dynamics during the first stage of the release (time < 10 s), whereas, during the remaining blowdown time, the simulated radiative heat flux at five sensors followed the trend observed in the experiment.

International Journal of Hydrogen Energy, 2019

The thermal hazards from ignited under-expanded cryogenic releases are not yet fully understood a... more The thermal hazards from ignited under-expanded cryogenic releases are not yet fully understood and reliable predictive tools are missing. This study aims at validation of a CFD model to simulate flame length and radiative heat flux for cryogenic hydrogen jet fires. The simulation results are compared against the experimental data by Sandia National Laboratories on cryogenic hydrogen fires from storage with pressure up to 5 bar abs and temperature in the range 48-82 K. The release source is modelled using the Ulster's notional nozzle theory. The problem is considered as steady-state. Three turbulence models were applied, and their performance was compared. The realizable k-ε model showed the best agreement with experimental flame length and radiative heat flux. Therefore, it has been employed in the CFD model along with Eddy Dissipation Concept for combustion and Discrete Ordinates (DO) model for radiation. A parametric study has been conducted to assess the effect of selected numerical and physical parameters on the simulations capability to reproduce experimental data. DO model discretization is shown to strongly affect simulations, indicating 10x10 as minimum number of angular divisions to provide a convergence. The simulations have shown sensitivity to experimental parameters such as humidity and exhaust system volumetric flow rate, highlighting the importance of accurate and extended publication of experimental data to conduct precise numerical studies. The simulations correctly reproduced the radiative heat flux from cryogenic hydrogen jet fire at different locations.

International Journal of Hydrogen Energy

Advances in Pulsed and Continuous Detonation, 2019

The development of computational §uid dynamics (CFD) model to simulate blast wave and ¦reball dyn... more The development of computational §uid dynamics (CFD) model to simulate blast wave and ¦reball dynamics after high-pressure hydrogen tank rupture in a ¦re is described. Parametric study is performed to de¦ne the e¨ect of submodels, numerical methods, and parameters on the convergence of the simulations and reproduction of experimental data. Experiments with initial pressure in hydrogen tank of 350 and 700 bar were used to validate the model. The e¨ect of hydrogen combustion and tank opening on the blast wave strength is assessed. The simulated cases include instantaneous tank opening and half tank opening.

International Journal of Hydrogen Energy

Hydrogen, Nov 7, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Health and Safety Executive, 2020

Hydrogen storage is now, and will continue to be a key topic for established and developing appli... more Hydrogen storage is now, and will continue to be a key topic for established and developing applications moving forward. The main priorities identified for hydrogen storage are: 1 st priority: tank fire resistance (previously identified as a priority in 2016). 2 nd priority: non-destructive testing techniques for manufacturing and regular inspection. 3 rd priority: understanding the effects of tank overheating on the structural performance and lifetime of the tank (also highlighted as a key priority by session chair to underpin refuelling protocols). (4) Key Session Topic: ACCIDENT PHYSICS of GASEOUS HYDROGEN For the accident physics of gaseous hydrogen the top three priorities from a list of five are: 1 st priority: premixed combustion associated with large scale problems with obstacles, flame acceleration and particularly deflagration-detonation-transition (DDT). 2 nd priority: hydrogen venting. 3 rd priority: ignition statistical approaches and spontaneous ignition. These priorities are key to growing application inventories and preventing and understanding the consequences of accidental releases in these new and developing scenarios. (5) Key Session Topic: ACCIDENT PHYSICS of LIQUID HYDROGEN For the accident physics of liquid hydrogen the top three priorities from an extensive list of 15 are: 1 st priority: multi-phase accumulations with explosion potential. 2 nd priority: combustion properties of cold gas clouds, especially in congested areas. 3 rd priority: knowledge and experience related to releases of large quantities. Obviously, this is an highly important area with a number of outstanding issues, many of which are beginning to be addressed by international efforts, such as the FCH JU project PRESLHY or the Norwegian project SH2IFT. These efforts are essential, as LH2 is key to a number of applications, as noted with the strong overlap in priorities with aerospace and maritime, and others that will need larger hydrogen inventories and corresponding scaling-up of supply infrastructure. (6) Key Session Topic: MATERIALS The rapid development and deployment of hydrogen applications leads to an expectation that the materials that enable the novel use of hydrogen today must become the normal, common place and safe materials (or their equivalents) for tomorrow. To meet this expectation, it is essential that the characteristics and long term performance and reliability of materials across all applications is understood, evidenced, catalogued and applied. With this in mind, the materials prioritisation exercise is divided into two sub-chapters, as it was in 2016.

Fuel cell vehicles store hydrogen onboard at pressure either 70 MPa (bikes, cars and tracks) or 3... more Fuel cell vehicles store hydrogen onboard at pressure either 70 MPa (bikes, cars and tracks) or 35 MPa (buses). Tank volume is 10-140 litres. More than 1/3 of CNG car tank ruptures in a fire are due to pressure relief device failure. The quantitative risk assessment of hydrogen onboard storage [1] has demonstrated that the acceptable level of risk 10 fatalities/vehicle/year can be achieved if storage tank has fire resistance rating above 47 min. This is based on the non-zero probability of thermally activated pressure relief device (TPRD) failure. The consequences of tank rupture in a fire are blast wave, fireball, projectiles. To underpin hydrogen safety engineering the underlying physical phenomena should be understood first. The aim of this study is to understand if there is a contribution of combustion into the blast wave strength.

International Journal of Hydrogen Energy

Jet flames originated by cryo-compressed ignited hydrogen releases can cause life-threatening con... more Jet flames originated by cryo-compressed ignited hydrogen releases can cause life-threatening conditions in their surroundings. Validated models are needed to accurately predict thermal hazards from a jet fire. Numerical simulations of cryogenic hydrogen flow in the release pipe are performed to assess the effect of heat transfer through the pipe walls on jet parameters. Notional nozzle exit diameter is calculated based on the simulated real nozzle parameters and used in CFD simulations as a boundary condition to model jet fires. The CFD model was previously validated against experiments with vertical cryogenic hydrogen jet fires with release pressures up to 0.5 MPa (abs), release diameter 1.25 mm and temperatures as low as 50 K. This study validates the CFD model in a wider domain of experimental release conditions - horizontal cryogenic jets at exhaust pipe temperature 80 K, pressure up to 2 MPa ab and release diameters up to 4 mm. Simulation results are compared against such experimentally measured parameters as hydrogen mass flow rate, flame length and radiative heat flux at different locations from the jet fire. The CFD model reproduces experiments with reasonable for engineering applications accuracy. Jet fire hazard distances established using three different criteria - temperature, thermal radiation and thermal dose - are compared and discussed based on CFD simulation results.

Hydrogen Knowledge Centre, Sep 6, 2018

Advances in Pulsed and Continuous Detonation, 2019

Energies, 2021

This work focuses on the experimental and numerical investigation of maximum overpressure and pre... more This work focuses on the experimental and numerical investigation of maximum overpressure and pressure dynamics during ignited hydrogen releases in a storage enclosure, e.g., in marine vessel or rail carriage, with limited vent size area, i.e., the pressure peaking phenomenon (PPP) revealed theoretically at Ulster University in 2010. The CFD model previously validated against small scale experiments in a 1 m3 enclosure is employed here to simulate real-scale tests performed by the University of South-Eastern Norway (USN) in a chamber with a volume of 15 m3. The numerical study compares two approaches on how to model the ignited hydrogen release conditions for under-expanded jets: (1) notional nozzle concept model with inflow boundary condition, and (2) volumetric source model in the governing conservation equations. For the test with storage pressure of 11.78 MPa, both approaches reproduce the experimental pressure dynamics and the pressure peak with a maximum 3% deviation. However,...

Engineering tools for calculation of hazard distances for cryogenic hydrogen jets are currently m... more Engineering tools for calculation of hazard distances for cryogenic hydrogen jets are currently missing. This study aims at the development of validated correlations for calculation of hazard distances for cryogenic unignited releases and jet fires. The experiments performed by Sandia National Laboratories (SNL) on jets from storage temperature in the range 46-295 K and pressure up to 6 bar abs are used to expand the validation domain of the correlations. The Ulster’s under-expanded jet theory is applied to calculate parameters at the real nozzle exit. The similarity law for concentration decay in momentum-dominated jets is shown to be capable to reproduce experimental data of SNL on 9 unignited cryogenic releases. The accuracy of the similarity law to predict experimentally measured axial concentration decay improves with the increase of the release diameter. This is thought due to decrease of the effect of friction and minor losses for large release orifices. The dimensionless fla...

Liquid hydrogen (LH2) compared to compressed gaseous hydrogen offers advantages for large scale t... more Liquid hydrogen (LH2) compared to compressed gaseous hydrogen offers advantages for large scale transport and storage of hydrogen with higher densities and potentially better safety performance. Although the gas industry has good experience with LH2 only little experience is available for the new applications of LH2 as an energy carrier. Therefore, the European FCH JU funded project PRESLHY conducts pre-normative research for the safe use of cryogenic LH2 in non-industrial settings. The work program consists of a preparatory phase, where the state of the art before the project has been summarized and where the experimental planning was adjusted to the outcome of a research priorities workshop. The central part of the project consists of 3 phenomena oriented work packages addressing Release, Ignition and Combustion with analytical approaches, experiments and simulations. The results shall improve the general understanding of the behavior of LH2 in accidents and thereby enhance the state-of-the-art, what will be reflected in appropriate recommendations for development or revision of specific international standards. The paper presents the status of the project at the middle of its terms.

International Journal of Hydrogen Energy, 2020

Sol-Gel zirconium-n-butoxide(ZNB) yttrium nitrate yttria-stabilized zirconia(YSZ). ZNB yttria! "#... more Sol-Gel zirconium-n-butoxide(ZNB) yttrium nitrate yttria-stabilized zirconia(YSZ). ZNB yttria! "# YSZ %& '()*+' ,-. /0. 100 o C1 2 34 56 7%&89:;, 400 o C1 <=%& %> ?@ A9.

International Journal of Hydrogen Energy, 2019

Thermal hazards from an under-expanded (900 bar) hydrogen jet fire have been numerically investig... more Thermal hazards from an under-expanded (900 bar) hydrogen jet fire have been numerically investigated. The simulation results have been compared with the flame length and radiative heat flux measured for the horizontal jet fire experiment conducted at INERIS. The release blowdown characteristics have been modelled using the volumetric source as an expanded implementation of the notional nozzle concept. The CFD study employs the realizable κ-ε model for turbulence and the Eddy Dissipation Concept for combustion. Radiation has been taken into account through the Discrete Ordinates (DO) model. The results demonstrated good agreement with the experimental flame length. Performance of the model shall be improved to reproduce the radiative properties dynamics during the first stage of the release (time < 10 s), whereas, during the remaining blowdown time, the simulated radiative heat flux at five sensors followed the trend observed in the experiment.

International Journal of Hydrogen Energy, 2019

The thermal hazards from ignited under-expanded cryogenic releases are not yet fully understood a... more The thermal hazards from ignited under-expanded cryogenic releases are not yet fully understood and reliable predictive tools are missing. This study aims at validation of a CFD model to simulate flame length and radiative heat flux for cryogenic hydrogen jet fires. The simulation results are compared against the experimental data by Sandia National Laboratories on cryogenic hydrogen fires from storage with pressure up to 5 bar abs and temperature in the range 48-82 K. The release source is modelled using the Ulster's notional nozzle theory. The problem is considered as steady-state. Three turbulence models were applied, and their performance was compared. The realizable k-ε model showed the best agreement with experimental flame length and radiative heat flux. Therefore, it has been employed in the CFD model along with Eddy Dissipation Concept for combustion and Discrete Ordinates (DO) model for radiation. A parametric study has been conducted to assess the effect of selected numerical and physical parameters on the simulations capability to reproduce experimental data. DO model discretization is shown to strongly affect simulations, indicating 10x10 as minimum number of angular divisions to provide a convergence. The simulations have shown sensitivity to experimental parameters such as humidity and exhaust system volumetric flow rate, highlighting the importance of accurate and extended publication of experimental data to conduct precise numerical studies. The simulations correctly reproduced the radiative heat flux from cryogenic hydrogen jet fire at different locations.