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Glass is one of the most ubiquitous materials in the world. Due to the extremely high temperatures required in the melting process, the glass industry is considered a hard-to-abate sector and poses major challenges to meet the net-zero target in the next decades. Since the highest share of emissions from glass production stems from the combustion of natural gas, its replacement with hydrogen is considered a promising solution to reduce the sector's environmental impact. This is the aim of the H2GLASS project, launched by the European Union at the beginning of 2023. In this context, addressing hydrogen-safety-related aspects is a top priority. In fact, due to hydrogen's peculiar flammability properties (e.g., wide flammability range, low ignition energy), its utilisation in furnaces may pose significant risks. In this study, a computational fluid dynamic (CFD) model is developed in Ansys Fluent to investigate hydrogen diffusion in enclosures following an accidental release. A grid and time-step sensitivity analyses are carried out to identify the best setup. The model is then validated against experimental data. The results of this work can be used as the starting point to build a CFD model suitable for studying hydrogen releases in large domains, such as glass manufacturing facilities, where obstacles and mechanical ventilation systems are present. [ABSTRACT FROM AUTHOR]

Liquid hydrogen (LH2) is believed to play a pivotal role in the energy transition. The main issue of this technology is the boil-off of the cryogenic liquid, particularly in the presence of critical heat sources, such as an external fire. Typically, in addition to the insulation system, safety barriers, such as water deluge systems and water curtains, are introduced as shields to protect the vessel from the fire radiation. Thus, the heat received from the cryogenic equipment depends on the effectiveness of those barriers. The present study aims at providing a dynamic quantification of the time to failure of an LH2 cryogenic tank, based on the performance of the abovementioned safety barriers. The results of this analysis highlight how different parameters affect the effectiveness of the safety systems, suggesting how to implement the most effective configurations. Moreover, the results obtained in terms of heat fluxes are precious input data useful for the definition of the boundary conditions in mathematical models (e.g., analytical and computational fluid dynamic models) used to investigate the behavior of cryogenic tanks engulfed in a fire. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising zero-emission fuel that could play a key role in the transition towards a more sustainable economy. It is regarded as a possible fuel for the future that could replace traditional fossil fuels and reduce the consequent amount of greenhouse gas emissions. In contrast with the undeniable benefits introduced by the use of hydrogen as a fuel, its hazardous properties rise concern from the safety standpoint. A potential loss of integrity of the storage equipment might lead to severe consequences such as fires and explosions. The current investigation aims at quantifying the impact of the outcomes of an unexpected hydrogen release from the storage vessels designed for hydrogen-powered buses. A comparative analysis is carried out considering the different conditions in which hydrogen is currently stored on board: as a high-pressure gas, as a cryogenic liquid or as a cryo-compressed gas. According to the operating conditions, a set of accident scenarios that may follow the release of hydrogen is identified and an event tree analysis is carried out to determine the resulting dangerous phenomena. The impact of such phenomena is assessed in terms of damage distances. The results of the study demonstrate the high hazardousness of cryo-compression and highlight that liquid and compressed hydrogen are the preferable solutions from a safety standpoint. [ABSTRACT FROM AUTHOR]