Publications

The present paper reviews the state-of-the-art of integrated structural integrity monitoring systems applicable to hydrogen on-board applications. Storage safety and costs are key issues for the success of the hydrogen technology considered for replacing the conventional fuel systems in transport applications. An in-service health monitoring procedure for high pressure vessels would contribute to minimize the risks associated to high pressure hydrogen storage and to improve the public acceptance. Such monitoring system would also enable a reduction on design burst criteria enabling savings in material costs and weight. This paper reviews safety and maintenance requirements based on present standards for high pressure vessels. A state-of-the-art of storage media and materials for onboard storage tank is presented as well as of current European programmes on hydrogen storage technologies for transport applications including design safety and system reliability. A technological road map is proposed for the development and validation of a prototype within the framework of the Portuguese EDEN project. To ensure safety an exhaustive test procedure is proposed. Furthermore requirements of a safety on-board monitoring system is defined for filament wound hydrogen tanks.

A simple approximate method for evaluation of blast effects and safety distances for unconfined hydrogen explosions is presented. The method includes models for flame speeds hydrogen distribution blast parameters and blast damage criteria. An example of the application of this methodology for hydrogen releases in three hypothetical obstructed areas with different levels of congestion is presented. The severity of the blast effect of unconfined hydrogen explosions is shown to depend strongly on the level of congestion for relatively small releases. Extremely large releases of hydrogen are predicted to be less sensitive to the congestion level.

Hydrogen is one of the important alternative fuels for future transportation. At the present stage research into hydrogen safety and designing risk mitigation measures are significant task. For compact storage of hydrogen in fuel cell vehicles storage of hydrogen under high pressure up to 40 MPa at refuelling stations is planned and safety in handling such high-pressure hydrogen is essential. This paper describes our experimental investigation into dispersion of high-pressure hydrogen gas which leaks through pinholes in the piping to the atmosphere. First in order to comprehend the basic behaviour of the steady dispersion of high-pressure hydrogen gas from the pinholes the time-averaged concentrations were measured. In our experiments initial release pressures of hydrogen gas were set at 20 MPa or 40 MPa and release diameters were in the range from 0.25 mm to 2 mm. The experimental results show that the hydrogen concentration along the axis of the dispersion plume can be expressed as a simple formula which is a function of the downwind distance X and the equivalent release diameter. This formula enables us to easily estimate the axial concentration (maximum concentration) at each downstream distance. However in order for the safety of flammable gas dispersion to be analyzed comparisons between time-averaged concentrations evaluated as above and lower flammable limit are insufficient. This is because even if time-averaged concentration is lower than the flammability limit instantaneous concentrations fluctuate and a higher instantaneous concentration occasionally appears due to turbulence. Therefore the time-averaged concentration value which can be used as a threshold for assessing safety must be determined considering concentration fluctuations. Once the threshold value is determined the safe distance from the leakage point can be evaluated by the above-mentioned simple formula. To clarify the phenomenon of concentration fluctuations instantaneous concentrations were measured with the fast-response flame ionization detector. A small amount of methane gas was mixed into the hydrogen as a tracer gas for this measurement. The relationship between the time-mean concentration and the occurrence probability of flammable concentration was analyzed. Under the same conditions spark-ignition experiments were also conducted and the relationship between the occurrence probability of flammable concentration and actual ignition probabilities were also investigated. The experimental results show that there is a clear correlation between the time-mean concentration the occurrence probability of flammable concentration flame length and occurrence probability of hydrogen flame.

The main objective of this study is an insight into physical phenomena underlying spontaneous ignition of hydrogen at sudden release from high pressure storage and its transition into the sustained jet fire. This paper describes modelling and large eddy simulation (LES) of spontaneous ignition dynamics in a tube with a rupture disk separating high pressure hydrogen storage and the atmosphere. Numerical experiments carried out by a LES model have provided an insight into the physics of the spontaneous ignition phenomenon. It is demonstrated that a chemical reaction commences in a boundary layer within the tube and propagates throughout the tube cross-section after that. Simulated by the LES model dynamics of flame formation outside the tube has reproduced experimental observation of combustion by high-speed photography including vortex induced “flame separation". It is concluded that the model developed can be applied for hydrogen safety engineering in particular for development of innovative pressure relief devices.

Nowadays consumer demand for local and global environmental quality in terms of air pollution and in particular greenhouse gas emissions reduction may help to drive to the introduction of zero emission vehicles. At this regard the hydrogen technology appears to have future market valuablepotential. On the other hand the use of hydrogen vehicles which requires appropriate infrastructures for production storage and refuelling stages presents a lot of safety problems due to the peculiar chemicophysical hydrogen characteristics. Therefore safe at the most practices are essential for the successful proliferation of hydrogen vehicles. Indeed to avoid limit hazards it is necessary to implement practices that if early adopted in the development of a fuelling station project can allow very low environmental impact safety being incorporated in the project itself. Such practices generally consist in the integrated use of Failure Mode and Effect Analysis (FMEA) HAZard OPerability (HAZOP) and Fault Tree Analysis (FTA) which constitute well established standards in reliability engineering. At this regard however a drawback is the lack of experience and the scarcity of the relevant data collection. In this work we present the results obtained by the integrated use of FMEA HAZOP and FTA analyses relevant for the moment the high-pressure storage equipment in a hydrogen gas refuelling station. The study that is intended to obtain elements for improving safety of the system can constitute a basis for further more refined works.

Hydrogen technology requires efficient and safe hydrogen storage systems. For this purpose storage in solid materials such as high capacity complex hydrides is studied intensely. Independent from the actual material to be used eventually any tank design will combine nanoscale powders of highly reactive material with pressurized hydrogen gas and so far little is known about the behaviour of these mixtures in case of incidents. For a first evaluation of a complex hydride in case of a tank failure NaAlH4 (doped with Ti) was investigated in a small scale tank failure tests. 80-100 ml of the material were filled into a heat exchanger tube and sealed under argon atmosphere with a burst disk. Subsequently the NaAlH4 was partially desorbed by heating. When the powder temperature reached 130 °C and the burst disk ruptured at 9 bar hydrogen overpressure the behaviour of the expelled powder was monitored using a high speed camera an IR camera as well as sound level meters. Expulsion of the hydrogen storage material into (dry) ambient atmosphere yields a dust cloud of finely dispersed powder which does not ignite spontaneously. Similar experiments including an external source of ignition (spark / water reacting with NaAlH4) yield a flame of reacting powder. The intensity will be compared to the reaction of an equivalent amount of pure hydrogen.

In the development of hydrogen technology special attention is paid to the technical problems of hydrogen storage. One possible way is cryogenic storage in liquid form. Generally cryo-technical machines need components with interacting surfaces in relative motion such as bearings seals or valves which are subjected to extreme conditions. Materials of such systems have to be resistant to friction-caused mechanical deformation at the surface low temperatures and hydrogen environment. Since materials failure can cause uncontrolled escape of hydrogen new material requirements are involved for these tribo-systems in particular regarding operability and reliability. In the past few years several projects dealing with the influence of hydrogen on the tribological properties of friction couples were conducted at the Federal Institute for Materials Research and Testing (BAM) Berlin. This paper reports some  investigations carried out with polymer composites. Friction and wear were measured for continuous sliding and analyses of the worn surfaces were performed after the experiments. Tests were performed at room temperature in hydrogen as well as in liquid hydrogen.

This paper presents a compilation of the results supplied by HySafe partners participating in the Standard Benchmark Exercise Problem (SBEP) V2 which is based on an experiment on hydrogen combustion that is first described. A list of the results requested from participants is also included. The main characteristics of the models used for the calculations are compared in a very succinct way by using tables. The comparison between results together with the experimental data when available is made through a series of graphs. The results show quite good agreement with the experimental data. The calculations have demonstrated to be sensitive to computational domain size and far field boundary condition.

Composite cylinders with metal liner are used for the storage of compressed hydrogen in automotive application. These hybrid pressure cylinders are designed for a nominal working pressure of up to 70 MPa. They also have to withstand a temperature range between -40°C and +85°C according GRPE draft [1] and for short periods up to a maximum temperature of 140°C during filling (fast filling) [2]. In order to exploit the material properties efficiently with a high degree of lightweight optimization and a high level of safety on the same time a better understanding of the structural behavior of hybrid designs is necessary. Work on this topic has been carried out in the frame of a work package on safety aspects and regulation (Subproject SAR) of the European IP StorHy (www.storhy.net). The temperature influence on the composite layers is distinctive due to there typical polymer material behavior. The stiffness of the composite layer is a function of temperature which influences global strains and stress levels (residual stresses) in operation. In order to do an accurate fatigue assessment of composite hybrid cylinders a realistic modeling of a representative temperature load is needed. For this climate data has been evaluated which were collected in Europe over a period of 30 years [3]. Assuming that the temperature follows a Gaussian (normal) distribution within the assessed period of 30 years it is possible to generate a frequency distribution for different temperature classes for the cold extreme and the hot extreme. Combining these distributions leads to the overall temperature range distribution (frequency over temperature classes). The climatic temperature influence the filling temperature and the pressure load have to be considered in combination with the operation profile of the storage cylinder to derive a complete load vector for an accurate assessment of the lifetime and safety level.

Climate change is one of today’s most pressing global challenges. Since the emission of greenhouse gases is often closely related to the use and supply of energy the goal to avoid emissions requires a fundamental restructuring of the energy system including all parts of the technology chains from production to end-use. Natural gas is today one of the most important primary energy sources in Europe with utilization ranging from power generation and industry to appliances in the residential and commercial sector as well as mobility. As natural gas is a fossil fuel gas utilization is thus responsible for significant emissions of carbon dioxide (CO₂ ) a greenhouse gas. However the transformation of the gas sector with its broad variety of technologies and end-use applications is a challenge as a fuel switch is related to changing physical properties. Today the residential and commercial sector is the biggest end user sector for natural gas in the EU both in terms of consumption and in the number of installed appliances. Natural gas is used to provide space heating as well as hot water and is used in cooking and catering appliances with in total about 200 million gas-fired residential and commercial end user appliances installed. More than 40 % of the EU gas consumption is accounted for by the residential and commercial sector. The most promising substitutes for natural gas are biogases and hydrogen. The carbon-free fuel gas hydrogen may be produced e.g. from water and renewable electricity; therefore it can be produced with a greatly lowered carbon footprint and on a very large scale. As a gaseous fuel it can be transported stored and utilised in all end-use sectors that are served by natural gas today: Power plants industry commercial appliances households and mobility. Technologies and materials however need to be suitable for the new fuel. The injection of hydrogen into existing gas distribution for example will impact all gas-using equipment in the grids since these devices are designed and optimized to operate safely efficiently and with low pollutant emissions with natural gas as fuel. The THyGA project1 focusses on all technical aspects and the regulatory framework concerning the potential operation of domestic and commercial end user appliances with hydrogen  / natural gas blends. The THyGA deliverables start with theoretical background from material science (D2.4) and combustion theory (this report) and extend to the project’s experimental campaign on hydrogen tolerance tests as well as reports on the status quo and potential future developments on rules and standards as well as mitigation strategies for coping with high levels of hydrogen admixture. By this approach the project aims at investigating which levels of hydrogen blending impact the various appliance technologies to which extent and to identify the regime in which a safe efficient and low-polluting operation is possible. As this is in many ways a question of combustion this report focuses on theoretical considerations about the impact of hydrogen admixture on combustion processes. The effects of hydrogen admixture on main gas quality properties as well as combustion temperatures laminar combustion velocities pollutant formation (CO NOx) safety-related aspects and the impact of combustion control are discussed. This overview provides a basis for subsequent steps of the project e.g. for establishing the testing program. A profound understanding of the impact on hydrogen on natural gas combustion is also essential for the development of mitigation strategies to reduce potential negative consequences of hydrogen admixture on appliances.

This is part one. Part two of this project can be found at this link

The 'Hydrogen for Heat' (Hy4Heat) programme aims to support the UK Government in its ambitions to decarbonise the UK energy sector in line with the targets of the Climate Change Act 2008 by attempting to evaluate and de-risk the natural gas to hydrogen network conversion option. The impact on the commercial sector is an important factor in understanding the feasibility of utilising hydrogen to decarbonise heat in the UK. The overall objective of the market research study Work Package 5 (WP5) was to determine if it is theoretically possible to successfully convert the commercial sector to hydrogen. This work will contribute to the understanding of the scale type and capacity of gas heating appliances within the sector providing a characterisation of the market and determining the requirements and feasibility for successfully transitioning them to hydrogen in the future.

This report and any attachment is freely available on the Hy4Heat website here. The report can also be downloaded directly by clicking on the pdf icon above 

If the general public is to use hydrogen as a vehicle fuel customers must be able to handle hydrogen with the same degree of confidence and with comparable risk as conventional liquid and gaseous fuels. The hazards associated with jet releases from leaks in a vehicle-refuelling environment must be considered if hydrogen is stored and used as a high-pressure gas since a jet release in a confined or congested area could result in an explosion. As there was insufficient knowledge of the explosion hazards a study was initiated to gain a better understanding of the potential explosion hazard consequences associated with high-pressure leaks from refuelling systems. This paper describes two experiments with a dummy vehicle and dispenser units to represent refuelling station congestion. The first represents a ‘worst-case’ scenario where the vehicle and dispensers are enveloped by a 5.4 m x 6.0 m x 2.5 m high pre-mixed hydrogen-air cloud. The second is an actual high-pressure leak from storage at 40 MPa (400 bar) representing an uncontrolled full-bore failure of a vehicle refuelling hose. In both cases an electric spark ignited the flammable cloud. Measurements were made of the explosion overpressure generated its evolution with time and its decay with distance. The results reported provide a direct demonstration of the explosion hazard from an uncontrolled leak; they will also be valuable for validating explosion models that will be needed to assess configurations and conditions beyond those studied experimentally.

Many countries including China have implemented supporting policies to promote the commercialized application of green hydrogen and hydrogen fuel cells. In this study a system dynamics (SD) model is proposed to study the evolution of hydrogen demand in China from the petroleum refining industry the synthetic ammonia industry and the vehicle market. In the model the impact from the macro-environment hydrogen fuel supply and construction of hydrogen facilities is considered to combine in incentives for supporting policies. To further formulate the competitive relationship in the vehicle market the Lotka–Volterra (LV) approach is adopted. The model is verified using published data from 2003 to 2017. The model is also used to forecast China’s hydrogen demand up to the year of 2030 under three different scenarios. Finally some forward-looking guidance is provided to policy makers according to the forecasting results.

This work programme was focused on identifying a suitable odorant for use in a 100% hydrogen gas grid (domestic use such as boilers and cookers). The research involved a review of existing odorants (used primarily for natural gas) and the selection of five suitable odorants based on available literature. One odorant was selected based on possible suitability with a Polymer Electrolyte Membrane (PEM) based fuel cell vehicle which could in future be a possible end-user of grid hydrogen. NPL prepared Primary Reference Materials containing the five odorants in hydrogen at the relevant amount fraction levels (as would be found in the grid) including ones provided by Robinson Brothers (the supplier of odorants for natural gas in the UK). These mixtures were used by NPL to perform tests to understand the effects of the mixtures on pipeline (metal and plastic) appliances (a hydrogen boiler provided by Worcester Bosch) and PEM fuel cells. HSE investigated the health and environmental impact of these odorants in hydrogen. Olfactory testing was performed by Air Spectrum to characterise the ‘smell’ of each odorant. Finally an economic analysis was performed by E4tech. The results confirm that Odorant NB would be a suitable odorant for use in a 100% hydrogen gas grid for combustion applications but further research would be required if the intention is to supply grid hydrogen to stationery fuel cells or fuel cell vehicles. In this case further testing would need to be performed to measure the extent of fuel cell degradation caused by the non-sulphur odorant obtained as part of this work programme and also other UK projects such as the Hydrogen Grid to Vehicle (HG2V) project[1] would provide important information about whether a purification step would be required regardless of the odorant before the hydrogen purity would be suitable for a PEM fuel cell vehicle. If purification was required it would be fine to use Odorant NB as this would be removed during the purification step.

This report and any attachment is freely available on the Hy4Heat website here. The report can also be downloaded directly by clicking on the pdf icon above 

An experimental study of flame propagation acceleration and transition to detonation in hydrogen-air mixture in 2 m long rectangular cross section channel filled with obstacles located at the bottom wall was performed. The initial conditions of the hydrogen-air mixture were 0.1 MPa and 293 K. Three different cases of obstacle height (blockage ratio 0.25 0.5 and 0.75) and four cases of obstacle density were studied with the channel height equal to 0.08 m. The channel width was 0.11 m in all experiments. The propagation of flame and pressure waves was monitored by four pressure transducers and four in house ion probes. The pairs of transducers and probes were placed at various locations along the channel in order to get information about the progress of the phenomena along the channel. To examine the influence of mixture composition on flame propagation and DDT the experiments were performed for the compositions of 20% 25% and 29.6% of H2 in air by volume. As a result of the experiments the deflagration and detonation regimes and velocities of flame propagation in the obstructed channel were determined.

The current work is devoted to problems connected with application of CFD tools for safety analysis of large-scale industrial structures. With the aim to preserve conservatism of overall process of multistage procedure of such analysis special efforts are required. A strategy which has to lead to obtaining of reliable results in CFD analysis is discussed. Different aspects of proposed strategy including: adequate choice of physical and numerical models procedure of validation simulations and problem of ‘under-resolved’ simulations are considered. For physical phenomena which could cause significant uncertainties in the course of scenario simulation an approach which complements CFD simulations by application of auxiliary criteria is presented. Physical basis and applicability of strong flame acceleration and detonation-to-deflagration transition criteria are discussed. In concluding part two examples of application of presented approach for nuclear power plant and workshop cell for hydrogen driven vehicles are presented.

We have investigated hydrogen explosion risk and its mitigation focusing on compact hydrogen refuelling stations in urban areas. In this study numerical analyses were performed of hydrogen blast propagation and the structural behaviour of barrier walls. Parametric numerical simulations of explosions were carried out to discover effective shapes for blast-mitigating barrier walls. The explosive source was a prismatic 5.27 m3 volume that contained 30% hydrogen and 70% air. A reinforced concrete wall 2 m tall by 10 m wide and 0.15 m thick was set 2 or 4 m away from the front surface of the source. The source was ignited at the bottom centre by a spark for the deflagration case and 10 g of C-4 high explosive for two detonation cases. Each of the tests measured overpressures on the surfaces of the wall and on the ground displacements of the wall and strains of the rebar inside the wall. The blast simulations were carried out with an in-house CFD code based on the compressive Euler equation. The initial energy estimated from the volume of hydrogen was a time-dependent function for the deflagration and was released instantaneously for the detonations. The simulated overpressures were in good agreement with test results for all three test cases. DIANA a finite element analysis code released by TNO was used for the structural simulations of the barrier wall. The overpressures obtained by the blast simulations were used as external forces. The analyses simulated the displacements well but not the rebar strains. The many shrinkage cracks that were observed on the walls some of which penetrated the wall could make it difficult to simulate the local behaviour of a wall with high accuracy and could cause strain gages to provide low-accuracy data. A parametric study of the blast simulation was conducted with several cross-sectional shapes of barrier wall. A T-shape and a Y-shape were found to be more effective in mitigating the blast.

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.

Today it is not known – neither qualitatively not quantitatively - how large the impact can be of the promoters on sensitivity to hydrogen-air detonation in hypothetical accidents at hydrogen-containing installations transport or storage facilities. Report goal is to estimate theoretically an effect of hydrogen-peroxide (as representative promoter) on sensitivity to detonation of the stoichiometric hydrogen-oxygen gas mixtures. The classical H₂-O2-Ar (2:1:7) gas mixture was chosen as reference system with the well established and unambiguously interpreted experimental data. In kinetic simulations it was found that the ignition delay time is sensitive to H₂O₂addition for small initial H₂O₂concentrations and is nearly constant for the large ones. Parametric reactive CFD studies of two dimensional cellular structure of 2H₂-O₂-7Ar-H₂O₂ detonations with variable hydrogen peroxide concentration (up to 10 vol.%) were also performed. Two un-expected results were obtained. First result: detonation cell size is practically independent upon variation of initial hydrogen peroxide concentration. For practical applications it means that presence of hydrogen-peroxide did not change drastically sensitivity of the stoichiometric hydrogen-oxygen gas mixtures. These theoretical speculations require an experimental verification. Second result: for large enough initial H₂O₂concentrations (> 1 vol.% at least) a new element of cellular structure of steady detonation wave was revealed. It is a system of multiple secondary longitudinal shock waves (SLSW) which propagates in the direction opposite to that of the leading shock wave. Detailed mechanism of SLSW formation is proposed.

Numerical simulations are carried out for a highly under-expanded hydrogen jet resulting from an accidental release of high-pressure hydrogen into the atmospheric environment. The predictions are made using two independent CFD codes namely CFX and KIVA. The KIVA code has been substantially modified by the present authors to enable large eddy simulation (LES). It employs a oneequation sub-grid scale (SGS) turbulence model which solves the SGS kinetic energy equation to allow for more relaxed equilibrium requirement and to facilitate high fidelity LES calculations with relatively coarser grids. Instead of using the widely accepted pseudo-source approach the complex shock structures resulting from the high under-expansion is numerically resolved in a small computational domain above the jet exit. The computed results are used as initial conditions for the subsequent hydrogen jet simulation. The predictions provide insight into the shock structure and the subsequent jet development. Such knowledge is valuable for studying the ignition characteristics of high-pressure hydrogen jets in the safety context.

In order for fuel cell vehicles to develop a widespread role in society it is essential that hydrogen refuelling stations become established. For this to happen there is a need to demonstrate the safety of the refuelling stations. The work described in this paper was carried out to provide experimental information on hydrogen outflow dispersion and explosion behaviour. In the first phase homogeneous hydrogen-air-mixtures of a known concentration were introduced into an explosion chamber and the resulting flame speed and overpressures were measured. Hydrogen concentration was the dominant factor influencing the flame speed and overpressure. Secondly high-pressure hydrogen releases were initiated in a storage room to study the accumulation of hydrogen. For a steady release with a constant driving pressure the hydrogen concentration varied as the inlet airflow changed depending on the ventilation area of the room the external wind conditions and also the buoyancy induced flows generated by the accumulating hydrogen. Having obtained this basic data the realistic dispersion and explosion experiments were executed at full-scale in the hydrogen station model. High-pressure hydrogen was released from 0.8-8.0mm nozzle at the dispenser position and inside the storage room in the full-scale model of the refuelling station. Also the hydrogen releases were ignited to study the overpressures that can be generated by such releases. The results showed that overpressures that were generated following releases at the dispenser location had a clear correlation with the time of ignition distance from ignition point.

Computational Fluid Dynamics codes are increasingly being considered for safety assessment demonstrations in many industrial fields as tools to model accidental phenomena and to design mitigation (risk reducing) systems. Thus they naturally complement experimental programmes which may be expensive to run or difficult to set up. However to trust numerical simulations the validity of the codes must be firmly established and a certain number of error sources (user effect modelling errors discretization errors etc) reduced to the minimum. Code validation and establishment of “best practice guidelines” in the application of simulation tools to hydrogen safety assessment are some of the objectives pursued by the HYSAFE Network of Excellence. This paper will contribute to these goals by describing some of the validation efforts that CEA is making in the areas of release dispersion combustion and mitigation thereby proposing the outline of a validation matrix for hydrogen safety problems.

In this paper the effect of direct diesel injection timing and engine speed on the performance and emissions of CI engine operating on RCCI (H2/diesel mixture) coupled with water injection have been numerically investigated and validated. The simulation have been carried out using GT-Power professional software. A single cylinder dual fuel compression ignition model has been built. The diesel fuel was injected directly to the cylinder. The hydrogen and water were injected to the engine intake manifold and engine port with constant mass flow rate and constant temperature for all engine speed. During the simulation the engine speed was varied from 1000 to 5000 rpm and the diesel injection timing was varied from (−5° to −25° CAD). In addition the optimized diesel injection timing for specific engine operation parameters has also been performed. The results show that for specific injection timing and constant hydrogen and water mass flow rate the increase of engine speed results in an increase in the cylinder temperature engine brake power brake specific fuel consumption and NO emissions; but decreases brake thermal efficiency. Moreover the analysis performed shows that the advanced injection timing decreases the engine power brake thermal efficiency and CO emissions; but increases NO emissions.

HyDeploy is a pioneering hydrogen energy project designed to help reduce UK CO2 emissions and reach the Government’s net zero target for 2050.

As the first ever live demonstration of hydrogen in homes HyDeploy aims to prove that blending up to 20% volume of hydrogen with natural gas is a safe and greener alternative to the gas we use now.  It is  providing evidence on how customers don’t have to change their cooking or heating appliances to take the blend which means less disruption and cost for them.

An essential part of a safety analysis to evaluate the risks of a liquid hydrogen (LH2) containing system is the understanding of cryogenic pool spreading and its vaporization. It represents the initial step in an accident sequence with the inadvertent spillage of LH2 e.g. after failure of a transport container tank or the rupture of a pipeline. This stage of an accident scenario provides pertinent information as a source term for the subsequent analysis steps of atmospheric dispersion and at presence of an ignition source the combustion of the hydrogen-air vapor cloud. A computer model LAUV has been developed at the Research Center Juelich which is able to simulate the spreading and vaporization of a cryogenic liquid under various conditions such as different grounds (solid water). It is based on the so-called shallow-layer differential equations taking into account physical phenomena such as ice formation if the cryogen is spilled on a water surface. The presentation will give a description of the computer model and its validation against existing experimental data. Furthermore calculational results will be analyzed describing the prediction and quantification of the consequences of an LH2 spill for different cases. They also include the comparison of an LH2 spillage versus the corresponding release of other cryogens such as liquid natural gas liquid oxygen and liquid nitrogen.