Canada
The ‘Green’ Ni-UGSO Catalyst for Hydrogen Production under Various Reforming Regimes
Jun 2021
Publication
A new spinelized Ni catalyst (Ni-UGSO) using Ni(NO3)2·6H2O as the Ni precursor was prepared according to a less material intensive protocol. The support of this catalyst is a negative-value mining residue UpGraded Slag Oxide (UGSO) produced from a TiO2 slag production unit. Applied to dry reforming of methane (DRM) at atmospheric pressure T = 810 °C space velocity of 3400 mL/(h·g) and molar CO2/CH4 = 1.2 Ni-UGSO gives a stable over 168 h time-on-stream methane conversion of 92%. In this DRM reaction optimization study: (1) the best performance is obtained with the 10–13 wt% Ni load; (2) the Ni-UGSO catalysts obtained from two different batches of UGSO demonstrated equivalent performances despite their slight differences in composition; (3) the sulfur-poisoning resistance study shows that at up to 5.5 ppm no Ni-UGSO deactivation is observed. In steam reforming of methane (SRM) Ni-UGSO was tested at 900 °C and a molar ratio of H2O/CH4 = 1.7. In this experimental range CH4 conversion rapidly reached 98% and remained stable over 168 h time-on-stream (TOS). The same stability is observed for H2 and CO yields at around 92% and 91% respectively while H2/CO was close to 3. In mixed (dry and steam) methane reforming using a ratio of H2O/CH4 = 0.15 and CO2/CH4 = 0.97 for 74 h and three reaction temperature levels (828 °C 847 °C and 896 °C) CH4 conversion remains stable; 80% at 828 °C (26 h) 85% at 847 °C (24 h) and 95% at 896 °C (24 h). All gaseous streams have been analyzed by gas chromatography. Both fresh and used catalysts are analyzed by scanning electron microscopy-electron dispersive X-ray spectroscopy (SEM-EDXS) X-ray diffraction (XRD) and thermogravimetric analysis (TGA) coupled with mass spectroscopy (MS) and BET Specific surface. In the reducing environment of reforming such catalytic activity is mainly attributed to (a) alloys such as FeNi FeNi3 and Fe3Ni2 (reduction of NiFe2O4 FeNiAlO4) and (b) to the solid solution NiO-MgO. The latter is characterized by a molecular distribution of the catalytically active Ni phase while offering an environment that prevents C deposition due to its alkalinity.
Development of Risk Mitigation Guidance for Hydrogen Sensor Placement Indoors and Outdoors
Sep 2021
Publication
Guidance on Sensor Placement remains one of the top priorities for the safe deployment of hydrogen and fuel cell equipment in the commercial marketplace. Building on the success of Phase l work reported at TCHS20l9 and published in TJHE this paper discusses the consecutive steps to further develop and validate such guidance for mechanically ventilated enclosures. The key step included a more in-depth analysis of sensitivity to variation of physical parameters in a small enclosure. and finally expansion of the developed approach to confined spaces in an outdoor environment.
Design and Simulation Studies of Hybrid Power Systems Based on Photovoltaic, Wind, Electrolyzer, and PEM Fuel Cells
May 2021
Publication
In recent years the need to reduce environmental impacts and increase flexibility in the energy sector has led to increased penetration of renewable energy sources and the shift from concentrated to decentralized generation. A fuel cell is an instrument that produces electricity by chemical reaction. Fuel cells are a promising technology for ultimate energy conversion and energy generation. We see that this system is integrated where we find that the wind and photovoltaic energy system is complementary between them because not all days are sunny windy or night so we see that this system has higher reliability to provide continuous generation. At low load hours PV and electrolysis units produce extra power. After being compressed hydrogen is stored in tanks. The purpose of this study is to separate the Bahr AL-Najaf Area from the main power grid and make it an independent network by itself. The PEM fuel cells were analyzed and designed and it were found that one layer is equal to 570.96 Watt at 0.61 volts and 1.04 A/Cm2 . The number of layers in one stack is designed to be equal to 13 layers so that the total power of one stack is equal to 7422.48 Watt. That is the number of stacks required to generate the required energy from the fuel cells is equal to 203 stk. This study provided an analysis of the hybrid system to cover the electricity demand in the Bahr AL-Najaf region of 1.5 MW the attained hybrid power system TNPC cost was about 9573208 USD whereas the capital cost and energy cost (COE) were about 7750000 USD and 0.169 USD/kWh respectively for one year.
Accumulation of Inert Impurities in a Polymer Electrolyte Fuel Cell System with Anode Recirculation and Periodic Purge: A Simple Analytical Model
Mar 2022
Publication
Anode recirculation with periodic purge is commonly used in polymer electrolyte fuel cell systems to control the accumulation of nitrogen water and other impurities that are present in the fuel or diffuse through the membrane from the cathode compartment. In this work we develop a simple generalized analytical model that simulates the time dependence of the accumulation of inert impurities in the anode compartment of such a system. It is shown that when there is transport out of the anode chamber the inert species is expected to accumulate exponentially until equilibrium is reached when the rate of inert entering the anode in the fuel supply and/or via crossover from the cathode is balanced by the rate of leakage and/or crossover to the cathode. The model is validated using recently published experimental data for the accumulation of N2 CH4 and CO2 in a recirculated system. The results show that nitrogen accumulation needs to be taken into account to properly adjust system parameters such as purge rate purge volume and recirculation rate. The use of this generalized analytical model is intended to aid the selection of these system parameters to optimize performance in the presence of inerts.
Integration of Wind Energy, Hydrogen and Natural Gas Pipeline Systems to Meet Community and Transportation Energy Needs: A Parametric Study
Apr 2014
Publication
The potential benefits are examined of the “Power-to-Gas” (P2G) scheme to utilize excess wind power capacity by generating hydrogen (or potentially methane) for use in the natural gas distribution grid. A parametric analysis is used to determine the feasibility and size of systems producing hydrogen that would be injected into the natural gas grid. Specifically wind farms located in southwestern Ontario Canada are considered. Infrastructure requirements wind farm size pipeline capacity geographical dispersion hydrogen production rate capital and operating costs are used as performance measures. The model takes into account the potential production rate of hydrogen and the rate that it can be injected into the local gas grid. “Straw man” systems are examined centered on a wind farm size of 100 MW integrating a 16-MW capacity electrolysis system typically producing 4700 kg of hydrogen per day.
Numerical Prediction of Lean Premixed Hydrogen Deflagrations in Vented Vessels
Sep 2021
Publication
In water-cooled nuclear power plants hydrogen gas can be generated by various mechanisms during an accident. In case combustion of the resulting hydrogen-air mixture within the facility occurs existing containment structures may be compromised and excessive radio-active material can be released to the environment. Thus an improved understanding of the propagation of lean hydrogen deflagrations within buildings and structures is essential for the development of appropriate accident management strategies associated with these scenarios. Following the accident in Fukushima Japan the application of three-dimensional computational fluid dynamics methods to high-fidelity detailed analysis of hydrogen combustion processes in both closed and vented vessels has become more widespread. In this study a recently developed large-eddy-simulation (LES) capability is applied to the prediction of lean premixed hydrogen deflagrations in vented vessels. The LES methodology makes use of a flamelet- or progress-variable-based combustion model coupled with an empirical burning velocity model (BVM) an anisotropic block-based adaptive mesh refinement (AMR) strategy an accurate finite-volume numerical scheme and a mesh independent subfilter-scale (SFS) model. Several different vessel and vent sizes and configurations are considered herein. The LES predictions are compared to experimental data obtained from the Large-Scale Vented Combustion Test Facility (LSVCTF) of the Canadian Nuclear Laboratories (CNL) with both quiescent and turbulent initial conditions. Following descriptions of the LES models LES results for both variable chamber sizes and single- and double-vent cases are presented to illustrate the capabilities of the proposed computational approach. In particular the predicted time histories of pressure as well as the maximum overpressure achieved within the vessels and combustion compartments are compared to those from the LSVCTF experiments. The influences of the modelled ignition process initial turbulence and mesh resolution on the LES results are also discussed. The findings highlight the potential and limitations of the proposed LES approach for accurately describing lean premixed hydrogen deflagrations within vented vessels.
Large-Scale Hydrogen Production Systems Using Marine Renewable Energies: State-of-the-Art
Dec 2023
Publication
To achieve a more ecologically friendly energy transition by the year 2050 under the European “green” accord hydrogen has recently gained significant scientific interest due to its efficiency as an energy carrier. This paper focuses on large-scale hydrogen production systems based on marine renewable-energy-based wind turbines and tidal turbines. The paper reviews the different technologies of hydrogen production using water electrolyzers energy storage unit base hydrogen vectors and fuel cells (FC). The focus is on large-scale hydrogen production systems using marine renewable energies. This study compares electrolyzers energy storage units and FC technologies with the main factors considered being cost sustainability and efficiency. Furthermore a review of aging models of electrolyzers and FCs based on electrical circuit models is drawn from the literature and presented including characterization methods of the model components and the parameters extraction methods using a dynamic current profile. In addition industrial projects for producing hydrogen from renewable energies that have already been completed or are now in progress are examined. The paper is concluded through a summary of recent hydrogen production and energy storage advances as well as some applications. Perspectives on enhancing the sustainability and efficiency of hydrogen production systems are also proposed and discussed. This paper provides a review of behavioral aging models of electrolyzers and FCs when integrated into hydrogen production systems as this is crucial for their successful deployment in an ever-changing energy context. We also review the EU’s potential for renewable energy analysis. In summary this study provides valuable information for research and industry stakeholders aiming to promote a sustainable and environmentally friendly energy transition.
Energy Performance Assessment of a Solar-driven Thermochemical Cycle Device for Green Hydrogen Production
Sep 2023
Publication
This paper presents a novel dynamic simulation model for assessing the energy performance of solar-driven systems employed in green hydrogen production. The system consists of a parabolic dish collector that focuses solar radiation on two cerium-based thermochemical reactors. The model is based on a transient finitedifference method to simulate the thermal behaviour of the system and it integrates a theoretical analysis of materials and operating principles. Different empirical data were considered for experimentally validating it: a good agreement between experimental and simulated results was obtained for the temperatures calculated inside the thermochemical reactor (R2 = 0.99 MAPE = 6.3%) and the hourly flow rates of hydrogen oxygen and carbon monoxide (R2 = 0.96 MAPE = 10%) inside the thermochemical reactor. The model was implemented in a MatLab tool for the system dynamic analysis under different boundary conditions. Subsequently to explore the capability of this approach the developed tool was used for analysing the examined device operating in twelve different weather zones. The obtained results comprise heat maps of specific crucial instants and hourly dynamic trends showing redox reaction cycles occurring into the thermochemical reactors. The yearly hydrogen production ranges from 1.19 m3 /y to 1.64 m3 /y according to the hourly incident solar radiations outdoor air temperatures and wind speeds. New graphic tools for rapid feasibility studies are presented. The developed tools and the obtained results can be useful to the basic design of this technology and for the multi-objective optimization of its layout and main design/operating parameters.
Enabling Safe and Sustainable Hydrogen Mobility: Circular Economy-Driven Management of Hydrogen Vehicle Safety
Sep 2023
Publication
Hydrogen vehicles encompassing fuel cell electric vehicles (FCEVs) are pivotal within the UK’s energy landscape as it pursues the goal of net-zero emissions by 2050. By markedly diminishing dependence on fossil fuels FCEVs including hydrogen vehicles wield substantial influence in shaping the circular economy (CE). Their impact extends to optimizing resource utilization enabling zero-emission mobility facilitating the integration of renewable energy sources supplying adaptable energy storage solutions and interconnecting diverse sectors. The widespread adoption of hydrogen vehicles accelerates the UK’s transformative journey towards a sustainable CE. However to fully harness the benefits of this transition a robust investigation and implementation of safety measures concerning hydrogen vehicle (HV) use are indispensable. Therefore this study takes a holistic approach integrating quantitative risk assessment (QRA) and an adaptive decision-making trial and evaluation laboratory (DEMATEL) framework as pragmatic instruments. These methodologies ensure both the secure deployment and operational excellence of HVs. The findings underscore that the root causes of HV failures encompass extreme environments material defects fuel cell damage delivery system impairment and storage system deterioration. Furthermore critical driving factors for effective safety intervention revolve around cultivating a safety culture robust education/training and sound maintenance scheduling. Addressing these factors is pivotal for creating an environment conducive to mitigating safety and risk concerns. Given the intricacies of conducting comprehensive hydrogen QRAs due to the absence of specific reliability data this study dedicates attention to rectifying this gap. A sensitivity analysis encompassing a range of values is meticulously conducted to affirm the strength and reliability of our approach. This robust analysis yields precise dependable outcomes. Consequently decision-makers are equipped to discern pivotal underlying factors precipitating potential HV failures. With this discernment they can tailor safety interventions that lay the groundwork for sustainable resilient and secure HV operations. Our study navigates the intersection of HVs safety and sustainability amplifying their importance within the CE paradigm. Using the careful amalgamation of QRA and DEMATEL methodologies we chart a course towards empowering decision-makers with the insights to steer the hydrogen vehicle domain to safer horizons while ushering in an era of transformative eco-conscious mobility.
Role of a Unitized Regenerative Fuel Cell in Remote Area Power Supply: A Review
Aug 2023
Publication
This manuscript presents a thorough review of unitized regenerative fuel cells (URFCs) and their importance in Remote Area Power Supply (RAPS). In RAPS systems that utilize solar and hydrogen power which typically include photovoltaic modules a proton exchange membrane (PEM) electrolyzer hydrogen gas storage and PEM fuel cells the cost of these systems is currently higher compared to conventional RAPS systems that employ diesel generators or batteries. URFCs offer a potential solution to reduce the expenses of solar hydrogen renewable energy systems in RAPS by combining the functionalities of the electrolyzer and fuel cell into a single unit thereby eliminating the need to purchase separate and costly electrolyzer and fuel cell units. URFCs are particularly well-suited for RAPS applications because the electrolyzer and fuel cell do not need to operate simultaneously. In electrolyzer mode URFCs function similarly to stand-alone electrolyzers. However in fuel cell mode the performance of URFCs is inferior to that of stand-alone fuel cells. The presented review summarizes the past present and future of URFCs with details on the operating modes of URFCs limitations and technical challenges and applications. Solar hydrogen renewable energy applications in RAPS and challenges facing solar hydrogen renewable energy in the RAPS is discussed in detail.
Synergistic Integration of Hydrogen Energy Economy with UK’s Sustainable Development Goals: A Holistic Approach to Enhancing Safety and Risk Mitigation
Oct 2023
Publication
Hydrogen is gaining prominence as a sustainable energy source in the UK aligning with the country’s commitment to advancing sustainable development across diverse sectors. However a rigorous examination of the interplay between the hydrogen economy and the Sustainable Development Goals (SDGs) is imperative. This study addresses this imperative by comprehensively assessing the risks associated with hydrogen production storage transportation and utilization. The overarching aim is to establish a robust framework that ensures the secure deployment and operation of hydrogen-based technologies within the UK’s sustainable development trajectory. Considering the unique characteristics of the UK’s energy landscape infrastructure and policy framework this paper presents practical and viable recommendations to facilitate the safe and effective integration of hydrogen energy into the UK’s SDGs. To facilitate sophisticated decision making it proposes using an advanced Decision-Making Trial and Evaluation Laboratory (DEMATEL) tool incorporating regret theory and a 2-tuple spherical linguistic environment. This tool enables a nuanced decision-making process yielding actionable insights. The analysis reveals that Incident Reporting and Learning Robust Regulatory Framework Safety Standards and Codes are pivotal safety factors. At the same time Clean Energy Access Climate Action and Industry Innovation and Infrastructure are identified as the most influential SDGs. This information provides valuable guidance for policymakers industry stakeholders and regulators. It empowers them to make well-informed strategic decisions and prioritize actions that bolster safety and sustainable development as the UK transitions towards a hydrogen-based energy system. Moreover the findings underscore the varying degrees of prominence among different SDGs. Notably SDG 13 (Climate Action) exhibits relatively lower overall distinction at 0.0066 and a Relation value of 0.0512 albeit with a substantial impact. In contrast SDG 7 (Clean Energy Access) and SDG 9 (Industry Innovation and Infrastructure) demonstrate moderate prominence levels (0.0559 and 0.0498 respectively) each with its unique influence emphasizing their critical roles in the UK’s pursuit of a sustainable hydrogen-based energy future.
A Techno-economic Study of the Strategy for Hydrogen Transport by Pipelines in Canada
Jan 2023
Publication
Hydrogen as a clean zero-emission energy fuel will play a critical role in energy transition and achievement of the net-zero target in 2050. Hydrogen delivery is integral to the entire value chain of a full-scale hydrogen economy. This work conducted a systematic review and analysis of various hydrogen transportation methods including truck tankers for liquid hydrogen tube trailers for gaseous hydrogen and pipelines by identifying and ranking the main properties and affecting factors associated with each method. It is found that pipelines especially the existing natural gas pipelines provide a more efficient and cheaper means to transport hydrogen over long distances. Analysis was further conducted on Canadian natural gas pipeline network which has been operating for safe effective and efficient energy transport over six decades. The established infrastructure along with the developed operating and management experiences and skillful manpower makes the existing pipelines the best option for transport of hydrogen in either blended or pure form in the country. The technical challenges in repurposing the existing natural gas pipelines for hydrogen service were discussed and further work was analyzed.
Potential of Salt Caverns for Hydrogen Storage in Southern Ontario, Canada
Jul 2023
Publication
Salt caverns produced by solution mining in Southern Ontario provide ideal spaces for gas storage due to their low permeability. Underground hydrogen storage (UHS) is an important part of the future renewable energy market in Ontario in order to achieve global carbon neutrality and to fill the gap left by retiring nuclear power plants. However large-scale hydrogen storage is still restricted by limited storage space on the ground’s surface. In this study hydrogen’s physical and chemical properties are first introduced and characterized by low molecular weight high diffusivity low solubility and low density. Then the geological conditions of the underground reservoirs are analyzed especially salt caverns. Salt caverns with their inert cavity environments and stable physical properties offer the most promising options for future hydrogen storage. The scales heights and thicknesses of the roof and floor salt layers and the internal temperatures and pressures conditions of salt caverns can affect stabilities and storage capacities. Finally several potential problems that may affect the safe storage of hydrogen in salt caverns are discussed. Through the comprehensive analysis of the influencing factors of hydrogen storage in salt caverns this study puts forward the most appropriate development strategy for salt caverns which provides theoretical guidance for UHS in the future and helps to reduce the risk of large-scale storage design.
AMHYCO Project - Towards Advanced Accident Guidelines for Hydrogen Safety in Nuclear Power Plants
Sep 2021
Publication
Severe accidents in nuclear power plants are potentially dangerous to both humans and the environment. To prevent and/or mitigate the consequences of these accidents it is paramount to have adequate accident management measures in place. During a severe accident combustible gases — especially hydrogen and carbon monoxide — can be released in significant amounts leading to a potential explosion risk in the nuclear containment building. These gases need to be managed to avoid threatening the containment integrity which can result in the releases of radioactive material into the environment. The main objective of the AMHYCO project is to propose innovative enhancements in the way combustible gases are managed in case of a severe accident in currently operating reactors. For this purpose the AMHYCO project pursues three specific activities including experimental investigations of relevant phenomena related to hydrogen / carbon monoxide combustion and mitigation with PARs (Passive Autocatalytic Recombiners) improvement of the predictive capabilities of analysis tools used for explosion hazard evaluation inside the reactor containment as well as enhancement of the Severe Accident Management Guidelines (SAMGs) with respect to combustible gases risk management based on theoretical and experimental results. Officially launched on 1 October 2020 AMHYCO is an EU-funded Horizon 2020 project that will last 4 years from 2020 to 2024. This international project consists of 12 organizations (six from European countries and one from Canada) and is led by the Universidad Politécnica de Madrid (UPM). AMHYCO will benefit from the worldwide experts in combustion science accident management and nuclear safety in its Advisory Board. The paper will give an overview of the work program and planned outcome of the project.
On the Bulk Transport of Green Hydrogen at Sea: Comparison Between Submarine Pipeline and Compressed and Liquefied Transport by Ship
Jan 2023
Publication
This paper compares six (6) alternatives for green hydrogen transport at sea. Two (2) alternatives of liquid hydrogen (LH2) by ship two (2) alternatives of compressed hydrogen (cH2) by ship and two (2) alternatives of hydrogen by pipeline. The ship alternatives study having hydrogen storage media at both end terminals to reduce the ships’ time at port or prescinding of them and reduce the immobilized capital. In the case of the pipeline new models are proposed by considering pressure costs. One scenario considers that there are compression stations every 500 km and the other one considers that there are none along the way. These alternatives are assessed under nine different scenarios that combine three distances: 100 km 2500 km and 5000 km; and three export rates of hydrogen 100 kt/y 1 Mt/y and 10 Mt/y. The results show including uncertainty bands that for the 100 km of distance the best alternative is the pipeline. For 2500 km and 100 kt/y the top alternative is cH2 shipping without storage facilities at the port terminals. For 2500 km and 1 Mt/y and for 5000 km and 100 kt/y the best alternatives are cH2 or LH2 shipping. For the remaining scenarios the best alternative is LH2 shipping.
Two-stage Model Predictive Control for a Hydrogen-based Storage System Paired to a Wind Farm Towards Green Hydrogen Production for Fuel Cell Electric Vehicles
Jul 2022
Publication
This study proposes a multi-level model predictive control (MPC) for a grid-connected wind farm paired to a hydrogen-based storage system (HESS) to produce hydrogen as a fuel for commercial road vehicles while meeting electric and contractual loads at the same time. In particular the integrated system (wind farm + HESS) should comply with the “fuel production” use case as per the IEA-HIA report where the hydrogen production for fuel cell electric vehicles (FCEVs) has the highest unconditional priority among all the objectives. Based on models adopting mixed-integer constraints and dynamics the problem of external hydrogen consumer requests optimal load demand tracking and electricity market participation is solved at different timescales to achieve a long-term plan based on forecasts that then are adjusted at real-time. The developed controller will be deployed onto the management platform of the HESS which is paired to a wind farm established in North Norway within the EU funded project HAEOLUS. Numerical analysis shows that the proposed controller efficiently manages the integrated system and commits the equipment so as to comply with the requirements of the addressed scenario. The operating costs of the devices are reduced by 5% which corresponds to roughly 300 commutations saved per year for devices.
Prospects and Technical Challenges in Hydrogen Production through Dry Reforming of Methane
Mar 2022
Publication
Environmental issues related to greenhouse gases (GHG) emissions have pushed the development of new technologies that will allow the economic production of low-carbon energy vectors such as hydrogen (H2 ) methane (CH4 ) and liquid fuels. Dry reforming of methane (DRM) has gained increased attention since it uses CH4 and carbon dioxide (CO2 ) which are two main greenhouse gases (GHG) as feedstock for the production of syngas which is a mixture of H2 and carbon monoxide (CO) and can be used as a building block for the production of fuels. Since H2 has been identified as a key enabler of the energy transition a lot of studies have aimed to benefit from the environmental advantages of DRM and to use it as a pathway for a sustainable H2 production. However there are several challenges related to this process and to its use for H2 production such as catalyst deactivation and the low H2/CO ratio of the syngas produced which is usually below 1.0. This paper presents the recent advances in the catalyst development for H2 production via DRM the processes that could be combined with DRM to overcome these challenges and the current industrial processes using DRM. The objective is to assess in which conditions DRM could be used for H2 production and the gaps in literature data preventing better evaluation of the environmental and economic potential of this process.
The Role of the Argon and Helium Bath Gases on the Detonation Structure of H2/)2 Mixture
Sep 2021
Publication
Recent modeling efforts of non-equilibrium effects in detonations have suggested that hydrogen-based detonations may be affected by vibrational non-equilibrium of the hydrogen and oxygen molecules effects which could explain discrepancies of cell sizes measured experimentally and calculated without relaxation effects. The present study addresses the role of vibrational relaxation in 2H2/O2 detonations by considering two-bath gases argon and helium. These two gases have the same thermodynamic and kinetic effects when relaxation is neglected. However due to the bath gases differences in molecular weight and reduced mass differences which affect the molecular collisions relaxation rates can be changed by approximately 50-70%. Experiments were performed in a narrow channel in mixtures of 2H2/O2/7Ar and 2H2/O2/7He to evaluate the role of the bath gas on detonation cellular structures. The experiments showed differences in velocity deficits and cell sizes for experimental conditions keeping the induction zone length constant in each of the mixtures. These differences were negligible in sensitive mixtures but increased with the increase in velocity deficits while the cell sizes approaching the channel dimensions. Near the limits differences of cell size in two mixtures approached a factor of 2. These differences were however reconciled by accounting for the viscous losses to the tube walls evaluated using a modified version of Mirels' laminar boundary layer theory and generalized Chapman-Jouguet theory for eigenvalue detonations. The experiments suggest that there is an influence of relaxation effects on the cellular structure of detonations which is more sensitive to wall boundary conditions. However the previous works showed that the impact of vibrational non-equilibrium in a mixture of H2/Air is more visible due to the effects of N2 in the air slowest to relax. Previous discrepancies suggested to be indicative of relaxation effects should be reevaluated by the inclusion of wall loss effects.
A Comparative Study of CFD-Modelling for Lean Premixed Hydrogen Deflagrations in Large-scale Vented Vessels
Sep 2021
Publication
Hydrogen combustion inside a post-accident nuclear reactor containment may pose a challenge to the containment integrity which could alter the fission-product release source term to the public. Combustion-generated overpressures may be relieved by venting to adjacent compartments through relief panels or existing openings. Thus an improved understanding of the propagation of lean hydrogen deflagrations in inter-connected compartments is essential for the development of appropriate management strategies. GOTHIC is a general purpose lumped parameter thermal-hydraulic code for solving multi-phase compressible flows which is accepted as an industry-standard code for containment safety analyses. Following the Fukushima accident the application of three-dimensional computational fluid dynamics methods to high-fidelity detailed analysis of hydrogen combustion processes has become more widespread. In this study a recently developed large-eddy-simulation (LES) capability is applied to the prediction of lean premixed hydrogen deflagrations in large-scale vented vessels of various configurations. The LES predictions are compared with GOTHIC predictions and experimental data obtained from the large-scale vented combustion test facility at the Canadian Nuclear Laboratories. The LES methodology makes use of a flamelet- or a progress-variable-based combustion model. An empirical burning velocity model is combined with an advanced finite-volume framework and a mesh-independent subfilter-scale model. Descriptions of the LES and GOTHIC modelling approaches used to simulate the hydrogen reactive flows in the vented vessels along with the experimental data sets are given. The potential and limitations of the lumped parameter and LES approaches for accurately describing lean premixed hydrogen deflagrations in vented vessels are discussed.
Potential for Natural Hydrogen in Quebec (Canada): A First Review
Mar 2024
Publication
The energy transition calls for natural hydrogen exploration with most occurrences discovered either inadvertently or more recently at the location of potentially diffusive circles observed from a change of vegetation cover at the surface. However some notable hydrogen occurrences are not directly associated with the presence of diffusive circles like the Bourakebougou field in Mali. Thus the objective of this work was to highlight geological areas that have some potential to find natural hydrogen in Quebec a Canadian province where no diffusive circles have yet been documented but which is rich in potential source rocks and where no exploration for natural hydrogen has been undertaken so far. A review of the different geological regions of Quebec was undertaken to highlight the relevant characteristics and geographical distribution of geological assemblages that may produce or have produced natural hydrogen in particular iron-rich rocks but also uranium-rich rocks supramature shales and zones where significant structural discontinuities are documented or suspected which may act as conduits for the migration of fluids of mantle origin. In addition to regional and local geological data an inventory of available geochemical data is also carried out to identify potential tracers or proxies to facilitate subsequent exploration efforts. A rating was then proposed based on the quality of the potential source rocks which also considers the presence of reservoir rocks and the proximity to end-users. This analysis allowed rating areas of interest for which fieldwork can be considered thus minimizing the exploratory risks and investments required to develop this resource. The size of the study area (over 1.5 million km2 ) the diversity of its geological environments (from metamorphic cratons to sedimentary basins) and their wide age range (from Archean to Paleozoic) make Quebec a promising territory for natural hydrogen exploration and to test the systematic rating method proposed here.
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