Safety
Functional Resonance Analysis for Emerging Risks in Hydrogen Handling: An Analysis of an Experimental Test
Oct 2024
Publication
Hydrogen is on the rise as a substitute for fossil fuel in the energy sector. While this substitution does not happen dramatically the steady increase in hydrogen related research might be a good indicator of such desire. As it stands there are issues regarding its safe handling and use; consequently the health and safety subsectors observe the situation conspicuously. As we yet to know the behavior of hydrogen in critical situations uncertainties make these tasks prone to emerging risks. Thus hydrogen safety falls under emerging risk studies. Conventional perspective on safety especially regarding the flammable material focuses on calculating the hypothetical risks of failures in system. Resilience Engineering has another perspective as it focuses on normal operations offering new perspectives to tackle emerging risks from a new angle. Born from the heart of Resilience Engineering the Functional Resonance Analysis Method (FRAM) captures sociotechnical systems’ essence in a tangible way. In this study FRAM has been used to model a series of experiments done on hydrogen management to analyze its jet fire. FRAM is used to test whether the method could be suitable to model a system in which emerging risks are present. It is the conclusion of this study that FRAM seems promising in raising risk awareness especially when available data is limited.
Towards Safer Hydrogen Refuelling Stations: Insights from Computational Fluid Dynamics LH2 Leakage
May 2024
Publication
The transition to a sustainable future with hydrogen as a key energy carrier necessitates a comprehensive understanding of the safety aspects of hydrogen including liquid hydrogen (LH₂). Hence this study presents a detailed computational fluid mechanics analysis to explore accidental LH₂ leakage and dispersion in a hydrogen refuelling station under varied conditions which is essential to prevent fire and explosion. The correlated impact of influential parameters including wind direction wind velocity leak direction and leak rate were analysed. The study shows that hydrogen dispersion is significantly impacted by the combined effect of wind direction and surrounding structures. Additionally the leak rate and leak direction have a significant effect on the development of the flammable cloud volume (FCV) which is critical for estimating the explosion hazards. Increasing wind velocity from 2 to 4 m/s at a constant leak rate of 0.06 kg/s results in an 82% reduction in FCV. The minimum FCV occurs when leak and wind directions oppose at 4 m/s. The most critical situation concerning FCV arises when the leak and wind directions are perpendicular with a leak rate of 0.06 kg/s and a wind velocity of 2 m/s. These findings can aid in the development of optimised sensing and monitoring systems and operational strategies to reduce the risk of catastrophic fire and explosion consequences.
Safety of Hydrogen Storage Technologies
Oct 2024
Publication
While hydrogen is regularly discussed as a possible option for storing regenerative energies its low minimum ignition energy and broad range of explosive concentrations pose safety challenges regarding hydrogen storage and there are also challenges related to hydrogen production and transport and at the point of use. A risk assessment of the whole hydrogen energy system is necessary to develop hydrogen utilization further. Here we concentrate on the most important hydrogen storage technologies especially high-pressure storage liquid hydrogen in cryogenic tanks methanol storage and salt cavern storage. This review aims to study the most recent research results related to these storage techniques by describing typical sensors and explosion protection measures thus allowing for a risk assessment of hydrogen storage through these technologies.
Influence of Air Changes Per Hour on Hydrogen Leaks in Mechanically Ventilated Enclosures
Mar 2024
Publication
The integration of hydrogen energy systems into nearly zero-emission buildings (nZEB) is emerging as a viable strategy to curtail greenhouse gas emissions associated with energy use in these buildings. However the indoor or outdoor placement of certain hydrogen system components or equipment necessitates stringent safety measures particularly in confined environments. This study aims to investigate the dynamics of hydrogen dispersion within an enclosure featuring forced ventilation analyzing the interplay between leakage flow rates and ventilation efficiency both experimentally and numerically. To simulate hydrogen's behavior helium gas which shares similar physical characteristics with hydrogen was utilized in experiments conducted at leakage flows of 4 8 and 10 L/min alongside a ventilation rate of 30 air changes per hour (ACH). The experiments revealed that irrespective of the leakage rate the oxygen concentration returned to its initial level approximately 11 min post-leakage at a ventilation rate of 30 ACH. This study also encompasses a numerical analysis to validate the experimental findings and assess the congruence between helium and hydrogen behaviors. Additionally the impact of varying ACH rates (30 45 60 75) on the concentrations of oxygen and hydrogen was quantified through numerical analysis for different hydrogen leakage rates (4 8 10 20 L/min). The insights derived from this research offer valuable guidance for building facility engineers on designing ventilation systems that ensure hydrogen and oxygen concentrations remain within safe limits in hydrogen-utilizing indoor environments.
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