Canada
Ignition Experiments of Hydrogen Mixtures by Different Methods and Description of the DRDC Test Facilities
Sep 2009
Publication
The paper will present results of hydrogen/oxygen mixtures ignited by using electric sparks electrostatic discharges a heating element and a flame. Measurements of the lower flammability limit (LFL) was done for each ignition method. The hydrogen mixtures of different concentrations were ignited at the bottom of a combustion chamber leading to an upward propagation of the resulting flame. At some level of concentration the combustion was partial due to the limited upward propagation. The complete combustion of the whole mixture was observed at concentration limits higher than the known LFL of 4% vol. for hydrogen in air. The paper will describe the test facilities and the resulting ignition probabilities for different ignition methods.
Fire Protection Strategy for Compressed Hydrogen-Powered Vehicles
Sep 2007
Publication
Virtually all major automotive companies are currently developing hydrogen-powered vehicles. The vast majority of them employ compressed hydrogen tanks and components as a means of storing the fuel onboard. Compressed hydrogen vehicle fuel systems are designed in the same way as compressed natural gas vehicles (NGV) i.e. the high pressure (up to 70 MPa) fuel is always contained within the system under all conditions with the exception of vehicular fire. In the event of a vehicle fire the fuel system is protected using a non-reclosing thermally activated pressure relief device (PRD) which safely vents the contents. Hydrogen fuel system PRDs are presently qualified to the performance requirements specified in draft hydrogen standards such ANSI/CSA HPRD 1 and EIHP Rev. 12b. They are also qualified with individual fuel tank designs in accordance with the engulfing bonfire requirements in various published/draft tank standards such as CSA B51 Part 2 JARI S001 SAE TIR J2579 ANSI/CSA HGV 2 ISO DIS 15869.2 and EIHP Rev. 12b. Since 2000 there have been over 20 documented NGV tank failures in service 11 of which have been attributed to vehicle fires. This paper will examine whether currently proposed hydrogen performance standards and installation requirements offer suitable fuel system protection in the event of vehicular fires. A number of alternative fire protection strategies will be discussed including:
- The requirement of an engulfing and/or localized fire test for individual tanks fuel systems and complete vehicles;
- The advantages/disadvantages of point source- surface area- and/or fuse-based PRDs
- The use of thermal insulating coatings/blankets for fire protection resulting in the NONventing of the fuel
- The specification of appropriate fuel system installation requirements to mitigate the effect of vehicular fires.
Alloy and Composition Dependence of Hydrogen Embrittlement Susceptibility in High-strength Steel Fasteners
Jun 2017
Publication
High-strength steel fasteners characterized by tensile strengths above 1100 MPa are often used in critical applications where a failure can have catastrophic consequences. Preventing hydrogen embrittlement (HE) failure is a fundamental concern implicating the entire fastener supply chain. Research is typically conducted under idealized conditions that cannot be translated into know-how prescribed in fastener industry standards and practices. Additionally inconsistencies and even contradictions in fastener industry standards have led to much confusion and many preventable or misdiagnosed fastener failures. HE susceptibility is a function of the material condition which is comprehensively described by the metallurgical and mechanical properties. Material strength has a first-order effect on HE susceptibility which increases significantly above 1200 MPa and is characterized by a ductile--brittle transition. For a given concentration of hydrogen and at equal strength the critical strength above which the ductile–brittle transition begins can vary due to second-order effects of chemistry tempering temperature and sub-microstructure. Additionally non-homogeneity of the metallurgical structure resulting from poorly controlled heat treatment impurities and non-metallic inclusions can increase HE susceptibility of steel in ways that are measurable but unpredictable. Below 1200 MPa non-conforming quality is often the root cause of real-life failures.
Link to document download on Royal Society Website
Link to document download on Royal Society Website
Canadian Hydrogen Safety Program.
Sep 2005
Publication
This paper discusses the rationale structure and contents of the Canadian Hydrogen Safety Program developed by the Codes & Standards Working Group of the Canadian Transportation Fuel Cell Alliance consisting of representatives from industry academia government and regulators. The overall program objective is to facilitate acceptance of the products services and systems of the Canadian Hydrogen Industry by the Canadian Hydrogen Stakeholder Community to facilitate trade ensure fair insurance policies and rates ensure effective and efficient regulatory approval procedures and to ensure that the interests of the general public are accommodated. The Program consists of four projects including Comparative Quantitative Risk Assessment of Hydrogen and Compressed Natural Gas (CNG) Refuelling Stations; Computational Fluid Dynamics (CFD) Modelling Validation Calibration and Enhancement; Enhancement of Frequency and Probability Analysis and Consequence Analysis of Key Component Failures of Hydrogen Systems; and Fuel Cell Oxidant Outlet Hydrogen Sensor Project. The Program projects are tightly linked with the content of the IEA Task 19 Hydrogen Safety. The Program also includes extensive (destructive and non-destructive) testing of hydrogen components.
Lagrangian Reaction-Diffusion Model for Predicting the Ignitability of Pressurized Hydrogen Releases
Sep 2009
Publication
Previous experiments demonstrated that the accidental release of high pressure hydrogen into air can lead to the possibility of spontaneous ignition. It is believed that this ignition is due to the heating of the mixing layer between hydrogen and air that is caused by the shock wave driven by the pressurized hydrogen during the release. Currently this problem is poorly understood and not amenable to direct numerical simulation. This is due to the presence of a wide range of scales between the sizes of the blast wave driven and the very thin mixing layer. The present study addresses this fundamental ignition problem and develops a solution framework in order to predict the ignition event for given hydrogen storage pressures and dimension of the release hole. In this problem only the mixing layer between the hydrogen and air is considered. This permits us to use much higher resolution than previous studies. This mixing layer at the jet head is advected as a Lagrangian fluid particle. The key physical processes in the problem are identified to be the mixing of the two gases at the mixing layer the initial heating by the shock wave and a cooling effect due to the expansion of the mixing layer. The results of the simulations indicate that for every storage pressure there exists a critical hole size below which ignition is prevented during the release process. Close inspection of the results indicate that this limit is due to the competition between the heating provided by the shock wave and the cooling due to expansion. Furthermore the results also indicate that the details of the mixing process do not play a significant role to leading order. The limiting ignition criteria were found to be well approximated by the Homogeneous Ignition Model of Cuenot and Poinsot supplemented by a heat loss term due to expansion. Therefore turbulent mixing occurring in reality is not likely to affect the ignition limits derived in the present study. Comparison with existing experiments showed very good agreement.
Design and Analysis of an Offshore Wind Power to Ammonia Production System in Nova Scotia
Dec 2022
Publication
Green ammonia has potential as a zero-emissions energy vector in applications such as energy storage transmission and distribution and zero-emissions transportation. Renewable energy such as offshore wind energy has been proposed to power its production. This paper designed and analyzed an on-land small-scale power-to-ammonia (P2A) production system with a target nominal output of 15 tonnes of ammonia per day which will use an 8 MW offshore turbine system off the coast of Nova Scotia Canada as the main power source. The P2A system consists of a reverse osmosis system a proton exchange membrane (PEM) electrolyser a hydrogen storage tank a nitrogen generator a set of compressors and heat exchangers an autothermal Haber-Bosch reactor and an ammonia storage tank. The system uses an electrical grid as a back-up for when the wind energy is insufficient as the process assumes a steady state. Two scenarios were analyzed with Scenario 1 producing a steady state of 15 tonnes of ammonia per day and Scenario 2 being one that switched production rates whenever wind speeds were low to 55% the nominal capacity. The results show that the grid connected P2A system has significant emissions for both scenarios which is larger than the traditional fossil-fuel based ammonia production when using the grid in provinces like Nova Scotia even if it is just a back-up during low wind power generation. The levelized cost of ammonia (LCOA) was calculated to be at least 2323 CAD tonne−1 for both scenarios which is not cost competitive in this small production scale. Scaling up the whole system reducing the reliance on the electricity grid increasing service life and decreasing windfarm costs could reduce the LCOA and make this P2A process more cost competitive.
A Review of Heavy-Duty Vehicle Powertrain Technologies Diesel Engine Vehicles, Battery Electric Vehicles, and Hydrogen Fuel Cell Electric Vehicles
Jun 2021
Publication
Greenhouse gas emissions from the freight transportation sector are a significant contributor to climate change pollution and negative health impacts because of the common use of heavy-duty diesel vehicles (HDVs). Governments around the world are working to transition away from diesel HDVs and to electric HDVs to reduce emissions. Battery electric HDVs and hydrogen fuel cell HDVs are two available alternatives to diesel engines. Each diesel engine HDV battery-electric HDV and hydrogen fuel cell HDV powertrain has its own advantages and disadvantages. This work provides a comprehensive review to examine the working mechanism performance metrics and recent developments of the aforementioned HDV powertrain technologies. A detailed comparison between the three powertrain technologies highlighting the advantages and disadvantages of each is also presented along with future perspectives of the HDV sector. Overall diesel engine in HDVs will remain an important technology in the short-term future due to the existing infrastructure and lower costs despite their high emissions while battery-electric HDV technology and hydrogen fuel cell HDV technology will be slowly developed to eliminate their barriers including costs infrastructure and performance limitations to penetrate the HDV market.
PRD Hydrogen Release and Dispersion, a Comparison of CFD Results Obtained from Using Ideal and Real Gas Law Properties.
Sep 2005
Publication
In this paper CFD techniques were applied to the simulations of hydrogen release from a 400-bar tank to ambient through a Pressure Relieve Device (PRD) 6 mm (¼”) opening. The numerical simulations using the TOPAZ software developed by Sandia National Laboratory addressed the changes of pressure density and flow rate variations at the leak orifice during release while the PHOENICS software package predicted extents of various hydrogen concentration envelopes as well as the velocities of gas mixture for the dispersion in the domain. The Abel-Noble equation of state (AN-EOS) was incorporated into the CFD model implemented through the TOPAZ and PHOENICS software to accurately predict the real gas properties for hydrogen release and dispersion under high pressures. The numerical results were compared with those obtained from using the ideal gas law and it was found that the ideal gas law overestimates the hydrogen mass release rates by up to 35% during the first 25 seconds of release. Based on the findings the authors recommend that a real gas equation of state be used for CFD predictions of high-pressure PRD releases.
Feasibility Investigation of Hydrogen Refuelling Infrastructure for Heavy‐Duty Vehicles in Canada
Apr 2022
Publication
A potentially viable solution to the problem of greenhouse gas emissions by vehicles in the transportation sector is the deployment of hydrogen as alternative fuel. A limitation to the diffusion of the hydrogen‐fuelled vehicles option is the intricate refuelling stations that vehicles will require. This study examines the practical use of hydrogen fuel within the internal combustion engine (ICE)‐powered long‐haul heavy‐duty trucking vehicles. Specifically it appraises the techno‐ economic feasibility of constructing a network of long‐haul truck refuelling stations using hydrogen fuel across Canada. Hydrogen fuel is chosen as an option for this study due to its low carbon emissions rate compared to diesel. This study also explores various operational methods including variable technology integration levels and truck traffic flows truck and pipeline delivery of hydrogen to stations and the possibility of producing hydrogen onsite. The proposed models created for this work suggest important parameters for economic development such as capital costs for station construction the selling price of fuel and the total investment cost for the infrastructure of a nation‐ wide refuelling station. Results showed that the selling price of hydrogen gas pipeline delivery op‐ tion is more economically stable. Specifically it was found that at 100% technology integration the range in selling prices was between 8.3 and 25.1 CAD$/kg. Alternatively at 10% technology integration the range was from 12.7 to 34.1 CAD$/kg. Moreover liquid hydrogen which is delivered by trucks generally had the highest selling price due to its very prohibitive storage costs. However truck‐delivered hydrogen stations provided the lowest total investment cost; the highest is shown by pipe‐delivered hydrogen and onsite hydrogen production processes using high technology integration methods. It is worth mentioning that once hydrogen technology is more developed and deployed the refuelling infrastructure cost is likely to decrease considerably. It is expected that the techno‐economic model developed in this work will be useful to design and optimize new and more efficient hydrogen refuelling stations for any ICE vehicles or fuel cell vehicles.
Challenges and Important Considerations When Benchmarking Single-cell Alkaline Electrolyzers
Nov 2021
Publication
This study outlines an approach to identifying the difficulties associated with the bench-marking of alkaline single cells under real electrolyzer conditions. A challenging task in the testing and comparison of different catalysts is obtaining reliable and meaningful benchmarks for these conditions. Negative effects on reproducibility were observed due to the reduction in conditioning time. On the anode side a stable passivation layer of NiO can be formed by annealing of the Ni foams which is even stable during long-term operation. Electrical contact resistance and impedance measurements showed that most of the contact resistance derived from the annealed Ni foam. Additionally analysis of various overvoltages indicated that most of the total overvoltage comes from the anode and cathode activation overpotential. Different morphologies of the substrate material exhibited an influence on the performance of the alkaline single cell based on an increase in the ohmic resistance.
Simulations of Hydrogen Releases from a Storage Tanks- Dispersion and Consequences of Ignition
Sep 2005
Publication
We present results from hydrogen dispersion simulations from a pressurized reservoir at constant flow rate in the presence and absence of a wall. The dispersion simulations are performed using a commercial finite volume solver. Validation of the approach is discussed. Constant concentration envelopes corresponding to the 2% 4% and 15% hydrogen concentration in air are calculated for a subcritical vertical jet and for an equivalent subcritical horizontal jet from a high pressure reservoir. The consequences of ignition and the resulting overpressure are calculated for subcritical horizontal and vertical hydrogen jets and in the latter case compared to available experimental data.
Vertical Turbulent Buoyant Helium Jet - CFD Modelling and Validation
Sep 2005
Publication
In this paper a vertical turbulent round jet of helium was studied numerically using the PHOENICS software package. The flow was assumed to be steady incompressible and turbulent. The jet discharge Froude number was 14000 and the turbulent Schmidt number was 0.7. The incompressible Reynolds average Navier-Stokes equations and helium transport equation expressed in 2-D axisymmetric domain were applied to model the underlying helium release. The k-e RNG turbulence model was used for the calculations of the corresponding turbulent viscosity diffusivity velocity and concentration fields in the domain. The simulation results are compared with the experimental measurements from the earlier published studies on helium jets in non-buoyant jet region (NBJ) intermediate region (I) and buoyant plume region (BP). The numerical results show that the radial profiles of mean velocity and mean concentration are consistent with the empirical data scaled by the effective diameter and density-ratio dependence. The mean velocity and concentration fields along the axis of the jet agree with the decay laws correlated from the previous experiments. The discrepancy between the numerical and experimental data is within 10% proving that the current CFD model for gas release and dispersion is robust accurate and reliable and that the CFD technique can be used as an alternative to the experiments with similar helium jets. The authors believe that the current CFD model is well validated through this study and can be further extended to predict similar hydrogen releases and dispersion if the model is properly applied with hydrogen properties.
Boundary Layer Effects on the Critical Nozzle of Hydrogen Sonic Jet
Oct 2015
Publication
When hydrogen flows through a small finite length constant exit area nozzle the viscous effects create a fluid throat which acts as a converging-diverging nozzle and lead to Mach number greater than one at the exit if the jet is under-expanded. This phenomenon influences the mass flow rate and the dispersion cloud size. In this study the boundary layer effect on the unsteady hydrogen sonic jet flow through a 1 mm diameter pipe from a high pressure reservoir (up to 70 MPa) is studied using computational fluid dynamics with a large eddy simulation turbulence model. This viscous flow simulation is compared with a non-viscous simulation to demonstrate that the velocity is supersonic at the exit of a small exit nozzle and that the mass flow is reduced.
Estimation of Filling Time for Compressed Hydrogen Refueling
Mar 2019
Publication
In order to facilitate the application of hydrogen energy and ensure its safety the compressed hydrogen storage tank on board needs to be full of hydrogen gas within 3 minutes. Therefore to meet this requirement the effects of refueling parameters on the filling time need to be investigated urgently. For the purpose of solving this issue a novel analytical solution of filling time is obtained from a lumped parameter model in this paper. According to the equation of state for real gas and dimensionless numbers Nu and Re the function relationships between the filling time and the refueling parameters are presented. These parameters include initial temperature initial pressure inflow temperature final temperature and final pressure. These equations are used to fit the reference data the results of fitting show good agreement. Then the values of fitting parameters are further utilized so as to verify the validity of these formulas. We believe this study can contribute to control the hydrogen filling time and ensure the safety during fast filling process.
Measurements of Flow Velocity and Scalar Concentration in Turbulent Multi-component Jets
Sep 2017
Publication
Buoyancy effects and nozzle geometry can have a significant impact on turbulent jet dispersion. This work was motivated by applications involving hydrogen. Using helium as an experimental proxy buoyant horizontal jets issuing from a round orifice on the side wall of a circular tube were analyzed experimentally using particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques simultaneously to provide instantaneous and time-averaged flow fields of velocity and concentration. Effects of buoyancy and asymmetry on the resulting flow structure were studied over a range of Reynolds numbers and gas densities. Significant differences were found between the centreline trajectory spreading rate and velocity decay of conventional horizontal round axisymmetric jets issuing through flat plates and the pipeline leak-representative jets considered in the present study. The realistic pipeline jets were always asymmetric and found to deflect about the jet axis in the near field. In the far field it was found that the realistic pipeline leak geometry causes buoyancy effects to dominate much sooner than expected compared to horizontal round jets issuing through flat plates.
CFD Based Simulation of Hydrogen Release Through Elliptical Orifices
Sep 2013
Publication
Computational Fluid Dynamics (CFD) is applied to investigate the near exit jet behavior of high pressure hydrogen release into quiescent ambient air through different types of orifices. The size and geometry of the release hole can affect the possibility of auto-ignition. Therefore the effect of release geometry on the behavior and development of hydrogen jet issuing from non-axisymmetric (elliptical) and expanding orifices is investigated and compared with their equivalent circular orifices. A three-dimensional in-house code is developed using the MPI library for parallel computing to simulate the flow based on an inviscid approximation. Convection dominates viscous effects in strongly underexpanded supersonic jets in the vicinity of release exit justifying the use of the Euler equations. The transport (advection) equation is applied to calculate the concentration of hydrogen-air mixture. The Abel-Nobel equation of state is used because high pressure hydrogen flow deviates from the ideal gas assumption. This work effort is conducted to fulfill two objectives. First two types of circular and elliptic orifices with the same cross sectional area are simulated and the flow behavior of each case is studied and compared during the initial stage of release. Second the comparative study between expanding circular exit and its fixed counterpart is carried out. This evaluation is conducted for different sizes of nozzle with different aspect ratios.
Valorization and Sequestration of Hydrogen Gas from Biomass Combustion in Solid Waste Incineration NaOH Oxides of Carbon Entrapment Model (SWI-NaOH-OCE Model)
Dec 2019
Publication
The valorization of biomass-based solid wastes for both geotechnical engineering purposes and energy needs has been reviewed to achieve eco-friendly eco-efficient and sustainable engineering and reengineering of civil engineering materials and structures. The objective of this work was to review the procedure developed by SWI-NaOH-OCE Model for the valorization of biomass through controlled direct combustion and the sequestration of hydrogen gas for energy needs. The incineration model gave a lead to the sequestration of emissions released during the direct combustion of biomass and the subsequent entrapment of oxides of carbon and the eventual release of abundant hydrogen gas in the entrapment jar. The generation of geomaterials ash for the purpose of soil stabilization concrete and asphalt modification has encouraged greenhouse emissions but eventually the technology that has been put in place has made it possible to manage and extract these emissions for energy needs. The contribution from researchers has shown that hydrogen sequestration from other sources requires high amount of energy because of the lower energy states of the compounds undergoing thermal decomposition. But this work has presented a more efficient approach to release hydrogen gas which can easily be extracted and stored to meet the energy needs of the future as fuel cell batteries to power vehicles mobile devices robotic systems etc. More so the development of MXene as an exfoliated two-dimensional nanosheets with permeability and filtration selectivity properties which are connected to its chemical composition and structure used in hydrogen gas extraction and separation from its molecular combination has presented an efficient procedure for the production and management of hydrogen gas for energy purposes.
CFD Model Based Ann Prediction of Flammable Vapor Colour Formed by Liquid Hydrogen Spill
Sep 2021
Publication
Unintended releases can occur during the production storage transportation and filling of liquid hydrogen which may cause devastating consequences. In the present work liquid hydrogen leak is modeled in ANSYS Fluent with the numerical model validated using the liquid hydrogen spill test data. A three-layer artificial neural network (ANN) model is built in which the wind speed ground temperature leakage time and leakage rate are taken as the inputs the horizontal diffusion distance and vertical diffusion distance of combustible gas as the outputs of the ANN. The representative sample data derived from the detailed calculation results of the numerical model are selected via the orthogonal experiment method to train and verify the back propagation (BP) neural network. Comparing the calculation results of the formula fitting with the sample data the results show that the established ANN model can quickly and accurately predict the horizontal and vertical diffusion distance of flammable vapor cloud relatively. The influences of four parameters on the horizontal hazard distance as well as vertical hazard height are predicted and analyzed in the case of continuous overflow of liquid hydrogen using the ANN model.
Decarbonization of Cement Production in a Hydrogen Economy
Apr 2022
Publication
The transition to net-zero emission energy systems creates synergistic opportunities across sectors. For example fuel hydrogen production from water electrolysis generates by-product oxygen that could be used to reduce the cost of carbon capture and storage (CCS) essential in the decarbonization of clinker production in cement making. To assess this opportunity a techno-economic assessment was carried out for the production of clinker using oxy-combustion in a natural gas-fueled plant coupled to CCS. Material and energy flows were assessed in a reference case for clinker production (oxygen from air no CCS) and compared to oxy-combustion clinker production from either an air separation unit (ASU 95% O2) or water electrolysis (100% O2) both coupled to CCS. Compared to the reference air-combusted clinker plant oxy-combustion increases thermal energy demand by 7% and electricity demand by 137% for ASU and 67% for electrolytic oxygen. The levelized cost of oxygen supply ranges from $49/tO2 for an on-site ASU to pipelined electrolytic O2 at $35/tO2 (200 km) or $13/t O2 (20 km). The cost of clinker for the reference plant without CCS increases linearly from $84/t clinker to $193/t clinker at a carbon price of $0/tCO2 to $150/tCO2 respectively. With oxy-combustion and CCS the clinker production cost ranges from $119 to $122/t clinker reflecting a breakeven carbon price of $39 to $53/tCO2 compared to the reference case. The lower cost for the electrolytic supply of by-product oxygen compared to ASU oxygen must be balanced against the reliability of supply the pipeline transport distance and the charges that may be added by the hydrogen producer.
Sizing and Operation of a Pure Renewable Energy Based Electric System through Hydrogen
Nov 2021
Publication
Today in order to reduce the increase of the carbon dioxide emissions a large number of renewable energy resources (RES) are already implemented. Considering both the intermittency and uncertainty of the RES the energy storage system (ESS) is still needed for balancing and stabilizing the power system. Among different existing categories of ESS the hydrogen storage systems (HSS) have the highest energy density and are crucial for the RES integration. In addition RES are located in faraway regions and are often transmitted to the terminal consumption center through HVDC (high voltage direct current) due to its lower power loss. In this paper we present a power supply system that achieves low-carbon emissions through combined HSS and HVDC technology. First the combined HSS and the HVDC model are established. Secondly the rule-based strategy for operating the HSS microgrid is presented. Then an operating strategy for a typical network i.e. the pure RES generation station-HVDC transmission-microgrids is demonstrated. Finally the best sizing capacities for all components are found by the genetic algorithm. The results prove the efficiency of the presented sizing approach for a pure RES electric system.
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