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The Slow Burst Test as a Method for Probabilistic Quantification of Cylinder Degradation
Sep 2013
Publication
"The current practise of focusing the periodic retesting of composite cylinders primarily on the hydraulic pressure test has to be evaluated as critical - with regard to the damage of the specimen as well as in terms of their significance. This is justified by micro damages caused to the specimen by the test itself and by a lack of informative values. Thus BAM Federal Institute of Materials Research and Testing (Germany) uses a new approach of validation of composite for the determination of re-test periods. It enables the description of the state of a population of composite cylinders based on destructive tests parallel to operation.<br/>An essential aspect of this approach is the prediction of residual safe service life. In cases where it cannot be estimated by means of hydraulic load cycle tests as a replacement the creep or burst test remains. As a combination of these two test procedures BAM suggests the ""slow burst test SBT"". On this a variety of about 150 burst test results on three design types of cylinders with plastic liners are presented. For this purpose both the parameters of the test protocol as well as the nature and intensity of the pre-damage artificially aged test samples are analysed statistically. This leads first to an evaluation of the different types of artificial ageing but also to the clear recommendation that conventional burst tests be substituted totally if indented for assessment of composite pressure receptacles."
Materials Aspects Associated with the Addition of up to 20 mol% Hydrogen into an Existing Natural Gas Distribution Network
Sep 2019
Publication
The introduction of hydrogen into the UK natural gas main has been reviewed in terms of how materials within the gas distribution network may be affected by contact with up to 80% Natural Gas : 20 mol% hydrogen blend at up to 2 barg. A range of metallic polymeric and elastomeric materials in the gas distribution network (GDN) were assessed via a combination of literature review and targeted practical test programmes.
The work considered:
The work considered:
- The effect of hydrogen on metallic materials identified in the network
- The effect of hydrogen on polymeric materials identified in the network
- The effect of hydrogen exposure on polyethylene pipeline techniques (squeeze off and collar electrofusion)
Hydrogen Dispersion in a Closed Environment
Sep 2017
Publication
The highly combustible nature of hydrogen poses a great hazard creating a number of problems with its safety and handling. As a part of safety studies related to the use of hydrogen in a confined environment it is extremely important to have a good knowledge of the dispersion mechanism.<br/>The present work investigates the concentration field and flammability envelope from a small scale leak. The hydrogen is released into a 0.47 m × 0.33 m x 0.20 m enclosure designed as a 1/15 – scale model of a room in a nuclear facility. The performed tests evaluates the influence of the initial conditions at the leakage source on the dispersion and mixing characteristics in a confined environment. The role of the leak location and the presence of obstacles are also analyzed. Throughout the test during the release and the subsequent dispersion phase temporal profiles of hydrogen concentration are measured using thermal conductivity gauges within the enclosure. In addition the BOS (Background Oriented Schlieren) technique is used to visualise the cloud evolution inside the enclosure. These instruments allow the observation and quantification of the stratification effects.
Tests of the Vehicle’s Powertrain with Hydrogen Fuel Cells at a Low Temperature
Sep 2019
Publication
The article discusses issues related to the operation of fuel cells stack fed with hydrogen at low temperature. The test object was a Toyota Mirai passenger car equipped with this type of powertrain. Tests were carried out in a thermoclimatic chamber at the Cracow University of Technology. They had an initial character and their aim was to evaluate the work of individual subassemblies of the propulsion system including the hydrogen supply system in terms of operational safety.
Investigating the Hydrogen Storage Capacity of Surfactant Modified Graphene
Mar 2019
Publication
As the depletion of traditional fossil fuels and environmental pollution become a serious problem of human society researchers are actively finding renewable green energy sources. Considered as a clean efficient and renewable alternative Hydrogen energy is considered the most promising energy source. However the safe and efficient storage of hydrogen has become the major problem that hinders its application. To solve this gap this paper proposes to utilize surfactant modified graphene for hydrogen storage. With Hummers method and ultrasonic stripping method this study prepared graphene from graphene oxide with NaBH4. Surfactant sodium dodecylbenzene sulfonate (SDBS) was used as a dispersant during the reduction process to produce the dispersion-stabilized graphene suspensions. The characteristics of the graphene suspensions then were examined by XRD SEM TEM FT-IR Raman XPS TG and N2 adsorption-desorption tests. The hydrogen adsorption properties of the samples were investigated with Langmuir and Freundlich fitting. The results show that the adsorption behavior is consistent with the Freundlich adsorption model and the process is a physical adsorption.
A Vision for Hydrogen in New Zealand - Green Paper
Sep 2019
Publication
Green hydrogen has the potential to play a significant role in our energy system and could play an important role in decarbonising parts of our economy.
To assist with the development of the Hydrogen Green Paper MBIE assisted by consultants Arup – held four workshops with key stakeholders in Wellington Auckland Christchurch and New Plymouth. The workshops were well attended with a range of views expressed on the potential for hydrogen in New Zealand. Following the workshops we incorporated these views into a Hydrogen Green Paper which was released for public consultation. We sought feedback from the public and wider stakeholders about the challenges and opportunities of building a hydrogen economy in New Zealand as part of our renewable energy strategy. On 2 September 2019 we released the green paper – “A vision for hydrogen in New Zealand”. Consultation ended on 25 October 2019. The green paper looked at the scope of New Zealand’s hydrogen potential to frame discussions for a national strategy.
The green paper asked 27 questions about the challenges and opportunities and the Government’s role in nine key areas:
This green paper along with the submissions will feed into a wider renewable energy strategy for New Zealand. This will outline the renewable energy pathway to a clean green carbon neutral for New Zealand by 2050.
To assist with the development of the Hydrogen Green Paper MBIE assisted by consultants Arup – held four workshops with key stakeholders in Wellington Auckland Christchurch and New Plymouth. The workshops were well attended with a range of views expressed on the potential for hydrogen in New Zealand. Following the workshops we incorporated these views into a Hydrogen Green Paper which was released for public consultation. We sought feedback from the public and wider stakeholders about the challenges and opportunities of building a hydrogen economy in New Zealand as part of our renewable energy strategy. On 2 September 2019 we released the green paper – “A vision for hydrogen in New Zealand”. Consultation ended on 25 October 2019. The green paper looked at the scope of New Zealand’s hydrogen potential to frame discussions for a national strategy.
The green paper asked 27 questions about the challenges and opportunities and the Government’s role in nine key areas:
- Hydrogen production
- Hydrogen electricity nexus
- Hydrogen for mobility
- Hydrogen for industrial processes
- Hydrogen for seasonal power generation
- Decarbonisation of our gas
- Hydrogen for export
- Innovation expands job opportunities
- Transitioning the job market
This green paper along with the submissions will feed into a wider renewable energy strategy for New Zealand. This will outline the renewable energy pathway to a clean green carbon neutral for New Zealand by 2050.
Determination of Distribution Function Used in Monte Carlo Simulation on Safety Analysis of Hydrogen Vessels
Sep 2019
Publication
The test data of static burst strength and load cycle strength of composite pressure vessels are often described by GAUSSian normal or WEIBULL distribution function to perform safety analyses. The goodness of assumed distribution function plays a significant role in the inferential statistics to predict the population properties by using limited test data. Often GAUSSian and WEIBULL probability nets are empirical methods used to validate the distribution function; Anderson-Darling and Kolmogorov-Smirnov tests are the mostly favorable approaches for Goodness of Fit. However the different approaches used to determine the parameters of distribution function lead mostly to different conclusions for safety assessments.<br/>In this study six different methods are investigated to show the variations on the rates for accepting the composite pressure vessels according to GTR No. 13 life test procedure. The six methods are: a) Norm- Log based method b) Least squares regression c) Weighted least squares regression d) A linear approach based on good linear unbiased estimators e) Maximum likelihood estimation and f) The method of moments estimation. In addition various approaches of ranking function are considered. In the study Monte Carlo simulations are conducted to generate basic populations based on the distribution functions which are determined using different methods. Then the samples are extracted randomly from a population and evaluated to obtain acceptance rate. Here the “populations” and “samples” are corresponding to the burst strength or load cycle strength of the pressure vessels made from composite material and a plastic liner (type 4) for the storage of hydrogen. To the end the results are discussed and the best reliable methods are proposed.
Hydrogen Compatibility of Austenitic Stainless Steel Tubing and Orbital Tube Welds
Sep 2013
Publication
Refueling infrastructure for use in gaseous hydrogen powered vehicles requires extensive manifolding for delivering the hydrogen from the stationary fuel storage at the refueling station to the vehicle as well as from the mobile storage on the vehicle to the fuel cell or combustion engine. Manifolds for gas handling often use welded construction (as opposed to compression fittings) to minimize gas leaks. Therefore it is important to understand the effects of hydrogen on tubing and tubing welds. This paper provides a brief overview of on-going studies on the effects of hydrogen precharging on the tensile properties of austenitic stainless tubing and orbital tube welds of several austenitic stainless steels.
Laboratory Method for Simulating Hydrogen Assisted Degradation of Gas Pipeline Steels
Aug 2019
Publication
Integrity of natural gas transmission systems is of great importance for energy and environmental security. Deterioration occurs in gas transit pipelines due to operational conditions and action of corrosion and hydrogenating media and leads to changes in microstructure and mechanical properties of pipeline steels which influences on pipeline performance. Hydrogenation of metal during corrosion process together with working stresses facilitates a development of in-bulk damaging at nano- and microscales. Reducing brittle fracture resistance of pipeline steels under operation increases significantly a failure risk of gas pipelines associated with in-bulk material degradation. Therefore hydrogen assisted degradation of pipelines steels under operation calls for effective methods for in-laboratory accelerated degradation. The present study is devoted to the development of the procedure of laboratory simulation of in-service degradation of pipeline steels. The role of hydrogen in degradation of pipeline steels was analysed. The procedure of accelerated degradation of pipeline steels under the combined action of axial loading and hydrogen charging was developed and induced in the laboratory. The procedure was consisted in consistently subjecting of specimens to electrolytic hydrogen charging to an axial loading up and to an artificial aging. Pipeline steels in the different states (as-received post-operated aged and after in-laboratory degradation) were investigated. The tensile mechanical behaviour of steels and impact toughness were experimentally studied. It was definitely concluded that the applied procedure caused the changes in the metal mechanical properties at the same level compared to the properties degradation due to operation. The developed procedure enables on a laboratory scale simulating of pipeline steel degradation during long-term operation under simultaneous action of hydrogenation and working loading and it makes possible to predict the mechanical behaviour of pipeline steels during service.
The Dependence of Fatigue Crack Growth on Hydrogen in Warm-rolled 316 Austenitic Stainless Steel
Sep 2019
Publication
The fatigue crack growth rate of warm-rolled AISI 316 austenitic stainless steel was investigated by controlling rolling strain and temperature in argon and hydrogen gas atmospheres. The fatigue crack growth rates of warm-rolled 316 specimens tested in hydrogen decreased with increasing rolling temperature especially 400 °C. By controlling the deformation temperature and strain the influences of microstructure (including dislocation structure deformation twins and α′ martensite) and its evolution on hydrogen-induced degradation of mechanical properties were separately discussed. Deformation twins deceased and dislocations became more uniform with the increase in rolling temperature inhibiting the formation of dynamic α′ martensite during the crack propagation. In the cold-rolled 316 specimens deformation twins accelerated hydrogen-induced crack growth due to the α′ martensitic transformation at the crack tip. In the warm-rolled specimens the formation of α′ martensite around the crack tip was completely inhibited which greatly reduced the fatigue crack growth rate in hydrogen atmosphere.
Cyclic Voltammetry of a Cobaloxime Catalyst
Jul 2019
Publication
<br/>Cyclic Voltammetry Measurements performed on a Cobaloxime Catalyst designed for photochemical hydrogen production.
Regulations, Codes, and Standards (RCS) For Large Scale Hydrogen Systems
Sep 2017
Publication
Hydrogen has potential applications that require larger-scale storage use and handling systems than currently are employed in emerging-market fuel cell applications. These potential applications include hydrogen generation and storage systems that would support electrical grid systems. There has been extensive work evaluating regulations codes and standards (RCS) for the emerging fuel cell market such as the infrastructure required to support fuel cell electric vehicles. However there has not been a similar RCS evaluation and development process for these larger systems. This paper presents an evaluation of the existing RCS in the United States for large-scale systems and identifies potential RCS gaps. This analysis considers large-scale hydrogen technologies that are currently being employed in limited use but may be more widely used as large-scale applications expand. The paper also identifies areas of potential safety research that would need to be conducted to fill the RCS gaps. U.S. codes define bulk hydrogen storage systems but do not define large-scale systems. This paper evaluates potential applications to define a large-scale hydrogen system relative to the systems employed in emerging technologies such as hydrogen fuelling stations. These large-scale systems would likely be of similar size to or larger than industrial hydrogen systems.
Modelling and Simulation of Lean Hydrogen-air Deflagrations
Sep 2013
Publication
The paper describes CFD modelling of lean hydrogen mixture deflagrations. Large eddy simulation (LES) premixed combustion model developed at the University of Ulster to account phenomena related to large-scale deflagrations was adjusted specifically for lean hydrogen-air flames. Experiments by Kumar (2006) on lean hydrogen-air mixture deflagrations in a 120 m3 vessel at initially quiescent conditions were simulated. 10% by volume hydrogen-air mixture was chosen for simulation to provide stable downward flame propagation; experiments with the smallest vent area 0.55 m2 were used as having the least apparent flame instabilities affecting the pressure dynamics. Deflagrations with igniter located centrally near vent and at far from the vent wall were simulated. Analysis of simulation results and experimental pressure dynamics demonstrated that flame instabilities developing after vent opening made the significant contribution to maximum overpressure in the considered experiments. Potential causes of flame instabilities are discussed and their comparative role for different igniter locations is demonstrated.
Open-cathode PEMFC Heat Utilisation to Enhance Hydrogen Supply Rate of Metal Hydride Canisters
Mar 2019
Publication
In this paper the hydrogen supply to an open-cathode PEM fuel cell (FC) by using metal hydride (MH) storage and thermal coupling between these two components are investigated theoretically. One of the challenges in using MH hydrogen storage canisters is their limited hydrogen supply rate as the hydrogen release from MH is an endothermic reaction. Therefore in order to meet the required hydrogen supply rate high amounts of MH should be employed that usually suggests storage of hydrogen to be higher than necessary for the application adding to the size weight and cost of the system. On the other hand the exhaust heat (i.e. that is usually wasted if not utilised for this purpose) from open-cathode FCs is a low-grade heat. However this heat can be transferred to MH canisters through convection to heat them up and increase their hydrogen release rate. A mathematical model is used to simulate the heat transfer between PEMFC exhaust heat and MH storage. This enables the prediction of the required MH for different FC power levels with and without heat supply to the MH storage. A 2.5-kW open-cathode FC is used to measure the exhaust air temperature at different output powers. It was found that in the absence of heat supply from the FC to the MH canisters significantly higher number of MH canisters are required to achieve the required rate of hydrogen supply to the FC for sustained operation (specially at high power outputs). However using the exhaust hot air from the FC to supply heat to the MH storage can reduce the number of the MH canisters required by around 40% to 70% for power output levels ranging from 500 W to 2000 W.
Enabling Efficient Networks For Low Carbon Futures: Options for Governance and Regulation
Sep 2015
Publication
This report summarises key themes emerging from the Energy Technologies Institute’s (ETI) project ‘Enabling efficient networks for low carbon futures’. The project aimed to explore the options for reforming the governance and regulatory arrangements to enable major changes to and investment in the UK’s energy network infrastructures. ETI commissioned four expert perspectives on the challenges and options facing the UK.
Homogeneous and Inhomogeneous Hydrogen Deflagrations in 25 m3 Enclosure
Sep 2019
Publication
Explosion venting is a frequently used measure to mitigate the consequence of gas deflagrations in closed environments. Despite the effort to predict the vent area needed to achieved the protection through engineering formulas and CFD tools work has still to be done to reliably predict the outcome of a vented gas explosion. Most of available data derived from experimental campaigns performed in the past involved homogeneous conditions while especially in the case of a very buoyant gas such as hydrogen the most probable scenario that can follow and unintended release in a closed environment foresee the ignition of a stratified inhomogeneous mixture. University of Pisa performed experimental tests in a 25 m3 facility in homogeneous and inhomogeneous conditions. The present paper is aimed to share the results of hydrogen dispersion and deflagration tests and discuss the comparison of maximum peak overpressure generated in the two scenarios. Description of the experimental set-up includes all the details deemed necessary to reproduce the phenomenon with a CFD tool.
Experimental and Numerical Study on Spontaneous Ignition of Hydrogen-methane Jets in Air
Sep 2013
Publication
This paper is an investigation of the spontaneous ignition process of high-pressure hydrogen and hydrogen-methane mixtures injected into air. The experiments were conducted in a closed channel filled with air where the hydrogen or hydrogen–methane mixture depressurised through different tubes (diameters d = 6 10 and 14 mm and lengths L = 10 25 40 50 75 and 100 mm). The methane addition to the mixture was 5% and 10% vol. The results showed that only 5% methane addition may increase even 2.67 times the pressure at which the mixture may ignite in comparison to the pressure of the pure hydrogen flow. The 10% of methane addition did not provide an ignition for burst pressures up to 15.0 MPa in the geometrical configuration with the longest tube (100 mm). Additionally the simulations of the experimental configuration with pure hydrogen were performed with the use of KIVA numerical code with full kinetic reaction mechanism.
Numerical Study on Combustion and Emission Characteristics of a PFI Gasoline Engine with Hydrogen Direct-Injection
Mar 2019
Publication
In this paper the effects of hydrogen blending radio and EGR rate on combustion and emission characteristics of a PFI gasoline engine with hydrogen direct-injection have been investigated by numerical modelling methods using a new generation of CFD simulation software CONVERGE. Results showed that compared with original engine hydrogen direct-injection PFI gasoline engine had a better performance on combustion characteristics but it also had a disadvantage of increasing NOx emissions. With the increase of hydrogen blending radio combustion duration shortened and CA50 advanced and was closer to TDC. And CO and THC emissions decreased however NOx emission increased. The variations of the combustion and emission characteristics followed by the increase of the EGR rate were exactly the opposite to the change of hydrogen blending radio. Considering both the combustion and emission characteristics using moderate EGR rate (15%~20%) under high hydrogen blending radio (15%~20%) condition can realize the simultaneous improvement of combustion and emission performance.
Comparisons of Helium and Hydrogen Releases in 1 M3 and 2 M3 Two Vents Enclosures: Concentration Measurements at Different Flow Rates and for Two Diameters of Injection Nozzle
Oct 2015
Publication
This work presents a parametric study on the similitude between hydrogen and helium distribution when released in the air by a source located inside of a naturally ventilated enclosure with two vents. Several configurations were experimentally addressed in order to improve knowledge on dispersion. Parameters were chosen to mimic operating conditions of hydrogen energy systems. Thus the varying parameters of the study were mainly the source diameter the releasing flow rate the volume and the geometry of the enclosure. Two different experimental set-ups were used in order to vary the enclosure's height between 1 and 2 m. Experimental results obtained with helium and hydrogen were compared at equivalent flow rates determined with existing similitude laws. It appears for the plume release case that helium can suitably be used for predicting hydrogen dispersion in these operating designs. On the other hand – when the flow turns into a jet – non negligible differences between hydrogen and helium dispersion appear. In this case helium – used as a direct substitute to hydrogen – will over predict concentrations we would get with hydrogen. Therefore helium concentration read-outs should be converted to obtain correct predictions for hydrogen. However such a converting law is not available yet.
Using Hydrogen Reactors to Improve the Diesel Engine Performance
Apr 2022
Publication
This work is aimed at solving the problem of converting diesel power drives to diesel– hydrogen fuels which are more environmentally friendly and less expensive alternatives to diesel fuel. The method of increasing the energy efficiency of diesel fuels has been improved. The thermochemical essence of using methanol as an alternative fuel to increase energy efficiency based on the provisions of thermotechnics is considered. Alternative methanol fuel has been chosen as the initial product for the hydrogen conversion process and its energy value cost and temperature conditions have been taken into account. Calculations showed that the caloric effect from the combustion of the converted mixture of hydrogen H2 and carbon monoxide CO exceeds the effect from the combustion of the same amount of methanol fuel. Engine power and fuel energy were increased due to the thermochemical regeneration of engine exhaust gas heat. An experimental setup was created to study the operation of a converted diesel engine on diesel–hydrogen products. Experimental studies of power and environmental parameters of a diesel engine converted for diesel–hydrogen products were performed. The studies showed that the conversion of diesel engines to operate using diesel– hydrogen products is technically feasible. A reduction in energy consumption was accompanied by an improvement in the environmental performance of the diesel–hydrogen engine working together with a chemical methanol conversion thermoreactor. The formation of carbon monoxide occurred in the range of 52–62%; nitrogen oxides in the exhaust gases decreased by 53–60% according to the crankshaft speed and loading on the experimental engine. In addition soot emissions were reduced by 17% for the engine fueled with the diesel–hydrogen fuel. The conversion of diesel engines for diesel–hydrogen products is very profitable because the price of methanol is on average 10–20% of the cost of petroleum fuel.
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