http://manuscript.elsevier.com/S0360319921047765/pdf/S0360319921047765.pdf

Global hydrogen development - A technological and geopolitical overview

In order for fuel cell vehicles to develop a widespread role in society, it is essential that hydrogen refueling stations become established. For this to happen, there is a need to demonstrate the safety of the refueling 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 refueling 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. INTRODUCTION In order for the ‘hydrogen economy’ to become a reality, not only is their a requirement to develop the fuel cell technology and associated equipment and infrastructure in an economic manner, but also it is necessary to demonstrate that all aspects of the supply and use of hydrogen can be performed safely. Osaka Gas Co., Ltd. has been operating a hydrogen refuelling station [1] safely as a demonstration plant, in parallel with developing a compact hydrogen reformer [2], (see Figure 1). However, in 2003, Osaka Gas joined the Japanese National Project on Hydrogen, with the aim of carrying out further work to investigate the safety aspects of hydrogen refuelling stations. One of the particular aims of this work was to help establish a suitable ‘safety zone’ around such a station. Figure 1: Osaka Gas’s hydrogen station (left) and hydrogen production unit, HYSERVE (right)

/pdf/experimental-study-on-hydrogen-explosions-in-a-full-scale-2qidcio5vh.pdf

Experimental study on hydrogen explosions in a full-scale hydrogen filling station model

Clean hydrogen for mobility – Quo vadis?

Hydrogen plays an increasingly significant role in solving the greenhouse effect and energy crisis as a clean fuel that can be obtained by renewable energy, and as a storable energy carrier. As a prerequisite for process safety of hydrogen, issues such as hydrogen embrittlement, fire, and explosion, have been of great interest to research scholars for decades. Based on bibliometrics, this article aims to provide a knowledge structure of publications related to hydrogen safety. Information about 369, 535 and 462 publications related to hydrogen safety from 1957 to 2021 were retrieved from the Web of Science Core Collection, Scopus, and Lens, respectively. The visualization software VOSviewer was employed to carry out the bibliometric analysis. The study found that the USA has the most publications among all countries; the publications from the International Journal of Hydrogen Energy rank the first among all source journals. Based on the advancement of time period, the hot terms in hydrogen safety research can be divided into three themes: storage and detection, combustion and explosion, and ignition and propagation. The results provide a comprehensive overview of this field of research and can help researchers quickly understand the research frontier and the overall status. 

A bibliometric study on research trends in hydrogen safety

The safe design and operation of clean fuels like hydrogen require a detailed understanding of their explosion characteristics. An experimental study of the flame propagation behavior influenced by quadrangular, cylindrical, and triangular obstacles was executed in a 530 mm × 82 mm × 82 mm pipe. The results confirm the understanding that obstacles with a tip promote the generation of flow instability and produce a more intense burning behavior of the flame. The shear layers shed fewer larger vortices after the quadrangular obstacle; however, these vortices can be dislodged to form smaller and more vortices after passing through the triangular obstacles. The shear layer has weak shedding properties behind obstacles with curved edges. In the flame propagation process, the quadrangular obstacles have a more obvious promoting effect of the initial explosion, but the degree is weaker than with the triangular obstacles. The effect of the quadrangular obstacles on flame velocity is mainly influenced by gas flow at the flame front. In triangular obstacles, the shear layer became prominent in the later stage of the explosion process and this contributes to enhancing the flame velocity and overpressure. 

Analysis of obstacle shape on gas explosion characteristics

Hydrogen is considered an excellent clean fuel with potential applications in several fields. There are serious safety concerns associated with the hydrogen process. These concerns need to be thoroughly understood and addressed to ensure its safe operation. To better understand the safety challenges of hydrogen use, application, and process, it is essential to undertake a detailed risk analysis. This can be achieved by performing detailed consequence modellings and assessing risk using the computational fluid dynamics (CFD) approach. This study comprehensively reviews and analyses safety challenges related to hydrogen, focusing on hydrogen storage, transmission, and application processes. Range of release and dispersion scenarios are investigated to analyse associated hazards. Approaches to quantitative risk assessment are also briefly discussed.

Elham Abohamzeh

Papers

Review of hydrogen safety during storage, transmission, and applications processes