Publications

This paper examines the helium dispersion behaviour in a 16.6 m3 enclosure with a small opening in the floor and distributed leaks along the edges. Helium a simulant for hydrogen was injected near the center of the floor with an injection rate ranging from 2 to 50 standard liters per minute (Richardson number of 0.3–134) through an upward-facing nozzle. In a short-term transient the helium distribution predicted with the models of Baines & Turner (1969) and Worster & Huppert (1983) matched the measured distributions reasonably well. In a long-term transient the vertical helium profile always reached a steady state which consisted of a homogenous layer at the top overlaying a stratified layer at the bottom. The helium transients in the uniform layer predicted with the models of Lowesmith (2009) and Prasad & Yang (2010) assuming a vent was located in the ceiling were in good agreement with the measured transients.

The competition between chemical energy release rate and volumetric expansion related to shock wave’s dynamics is of primary importance for a number of situations relevant to explosion safety. While studies have been performed on this topic over the years they have been limited to mixtures with monotonous energy release profile. In the present study the ignition of H2-NO2/N2O4 mixtures which exhibit a single-step or a two-step energy release rate profile depending on the equivalence ratio has been investigated under volumetric expansion conditions. The rate of expansion has been calculated using the Taylor-Sedov solution and accounted for using 0-D numerical simulations with time-dependent specific volume. The results were analyzed in terms of a Damkohler number defined as the ratio of the expansion to ignition times. For mixtures with non-monotonous energy release rate profiles two critical Damkohler numbers can be identified one for each of the steps of energy release. It was also shown that the fluid element which is the most likely to ignite corresponds to the one behind a shock propagating at the Chapman-Jouguet velocity. The thermo-chemical dynamics have been analyzed about the critical conditions using energy release rate per reaction rate of production and sensitivity analyses.

In this study an explosion channel is used to investigate flame dynamics in homogeneous hydrogencarbon monoxide-air (H2-CO-air) mixtures. The test rig is a small scale 6 m channel at a rectangular cross section of 300x60 mm. Obstacles of a blockage ratio of BR=60% and a spacing of s=300mm are placed in first part of the channel. A 2.05 m long unobstructed part in the rear of the channel allows for investigation of freely propagating flames and detonations. The fuel composition is varied from 100/0 to 50/50 Vol.-% H2/CO mixtures. The overall fuel content ranges from 15 to 40 Vol.-% in air aiming to obtain fast flames and deflagration-to-detonation transition (DDT). Flame speed and dynamic pressure data are evaluated. Results extend data obtained by [1] and can be used for validation of numerical frameworks. Limits for fast flames and DDT in homogeneous H2-CO-air mixtures at the given geometry are presented.

The Prime Minister’s Ten Point Plan has set out the measures that will help ensure the UK is at the forefront of this revolution just as we led the first over two centuries ago. As nations move out of the shadow of coronavirus and confront the challenge of climate change with renewed vigour markets for new green products and services will spring up round the world. Taking action now will help ensure not just that we end our contribution to climate change by achieving our target of net zero emissions. It will help position UK companies and our world class research base to seize the business opportunities which flow from it creating jobs and wealth for our country.

Following on from the Ten Point Plan and the National Infrastructure Strategy the Energy White Paper provides further clarity on the Prime Minister’s measures and puts in place a strategy for the wider energy system that:

• Transforms energy building a cleaner greener future for our country our people and our planet 
• Supports a green recovery growing our economy supporting thousands of green jobs across the country in new green industries and leveraging new green export opportunities
• Creates a fair deal for consumers protecting the fuel poor providing opportunities to save money on bills giving us warmer more comfortable homes and balancing investment against bill impacts.

This study presents a computational fluid dynamic (CFD) study of Dimethyl Ether steam reforming (DME-SR) in a large scale Circulating Fluidized Bed (CFB) reactor. The CFD model is based on Eulerian–Eulerian dispersed flow and solved using commercial software (ANSYS FLUENT). The DME-SR reactions scheme and kinetics in the presence of a bifunctional catalyst of CuO/ZnO/Al₂O₃+ZSM-5 were incorporated in the model using in-house developed user-defined function. The model was validated by comparing the predictions with experimental data from the literature. The results revealed for the first time detailed CFB reactor hydrodynamics gas residence time temperature distribution and product gas composition at a selected operating condition of 300 °C and steam to DME mass ratio of 3 (molar ratio of 7.62). The spatial variation in the gas species concentrations suggests the existence of three distinct reaction zones but limited temperature variations. The DME conversion and hydrogen yield were found to be 87% and 59% respectively resulting in a product gas consisting of 72 mol% hydrogen. In part II of this study the model presented here will be used to optimize the reactor design and study the effect of operating conditions on the reactor performance and products.

With downward trends in Australian equipment manufacturing there are increased numbers of overseas designed manufactured and certified hydrogen systems being introduced into Australia. In parallel there are also opportunities for hydrogen and its carriers to be exported to overseas. Certainty of reputable codes and standards is important to meet regulatory requirements and community safety expectations locally and overseas.

This paper is a progress report of Hydrogen Mobility Australia’s (HMA) Technical Committee on mapping the regulatory codes and standards (RCS) gaps in Australia and establishing a pathway together with Standards Australia and Commonwealth and State Governments. This paper will discuss the benefits of the pathway covering the areas of:

• Safety – Enable Australia to implement consensual rules to minimise avoidable risks to persons and goods to an acceptable level
• Environment – Ensure protection of the environment from unacceptable damage due to the operation and effects of products processes and services linked to hydrogen
• Elimination of barriers to trade – Provide consistency between international jurisdictions enabling streamlined entry of hydrogen related equipment from overseas
• Upskilling of Australian industry participants – Gain useful learnings from countries more advanced in their progress in implementing ISO standards and hydrogen sector development

This paper is jointly prepared by representatives of HMA Technical Committee and Department of Energy and Mining South Australian Government. The paper also highlights the initiatives of Commonwealth and State Governments to advance the hydrogen economy.

This discussion session interrogated the current understanding of hydrogen embrittlement mechanisms in steels. This article is a transcription of the recorded discussion of ‘Hydrogen in steels’ at the Royal Society Scientific Discussion Meeting ‘The challenges of hydrogen and metals’ 16–18 January 2017.

The text is approved by the contributors. E.L.S. transcribed the session. M.P. assisted in the preparation of the manuscript

Link to document download on Royal Society Website 

A larger adoption of hydrogen fuel-cell electric vehicles (FCEVs) is typically included in the strategies to decarbonize the transportation sector. This inclusion is supported by life-cycle assessments (LCAs) which show the potential greenhouse gas (GHG) emission benefit of replacing internal combustion engine vehicles with their fuel cell counterpart. However the literature review performed in this study shows that the effects of durability and performance losses of fuel cells on the life-cycle environmental impact of the vehicle have rarely been assessed. Most of the LCAs assume a constant fuel consumption (ranging from 0.58 to 1.15 kgH2/100 km) for the vehicles throughout their service life which ranges in the assessments from 120000 to 225000 km. In this study the effect of performance losses on the life-cycle GHG emissions of the vehicles was assessed based on laboratory experiments. Losses have the effect of increasing the life-cycle GHG emissions of the vehicle up to 13%. Moreover this study attempted for the first time to investigate via laboratory analyses the GHG implications of replacing the hydrophobic polymer for the gas diffusion medium (GDM) of fuel cells to increase their durability. LCA showed that when the service life of the vehicle was fixed at 150000 km the GHG emission savings of using an FC with lower performance losses (i.e. FC coated with fluorinated ethylene propylene (FEP) instead of polytetrafluoroethylene (PTFE)) are negligible compared to the overall life-cycle impact of the vehicle. Both the GDM coating and the amount of hydrogen saved account for less than 2% of the GHG emissions arising during vehicle operation. On the other hand when the service life of the vehicle depends on the operability of the fuel cell the global warming potential per driven km of the FEP-based FCEV reduces by 7 to 32%. The range of results depends on several variables such as the GHG emissions from hydrogen production and the initial fuel consumption of the vehicle. Higher GHG savings are expected from an FC vehicle with high consumption of hydrogen produced with fossil fuels. Based on the results we recommend the inclusion of fuel-cell durability in future LCAs of FCEVs. We also advocate for more research on the real-life performance of fuel cells employing alternative materials.

Hydrogen transport and trapping equations are implemented in a FE software using User Subroutines and the obtained tool is applied to get the diffusion fields in a metallic sheet submitted to a U-Bend test. Based on a submodelling process mechanical and diffusion fields have been computed at the polycrystal scale from which statistical evaluation of the risk of failure of the sample has been estimated.

Deployment and investments in hydrogen have accelerated rapidly in response to government commitments to deep decarbonisation establishing hydrogen as a key component in the energy transition.

To help guide regulators decision-makers and investors the Hydrogen Council collaborated with McKinsey & Company to release the report ‘Hydrogen Insights 2021: A Perspective on Hydrogen Investment Deployment and Cost Competitiveness’. The report offers a comprehensive perspective on market deployment around the world investment momentum as well as implications on cost competitiveness of hydrogen solutions.

The document can be downloaded from their website