Safety

Metal oxides (e.g. SnO2 ZnO TiO2) have been widely investigated materials for gas sensing applications including hydrogen detection. However the potential for hydrogen sensing of metal oxides such as CuO In2O3 NiO exhibiting p-type conduction has been largely overlooked. Over the last 15 years structures based on TiO2 and CuO have gained increasing interest as a promising system for hydrogen detection. Therefore this article aims to: 1) provide an overview of the performance of TiO2 as a reference material and discuss methods to enhance its sensing performance 2) summarize and highlight the role of copper oxides in hydrogen gas detection as the materials that have predominantly been studied for H2S detection 3) review efforts made to improve the sensing performance of heterostructures of CuTiOx from structures with charge compensation effect to those successfully sensing hydrogen 4) present the potential of CuTiOx for H2 detection.

Accurate and efficient prediction of thermal radiant of hydrogen jet fire is important to schedule safety design and emergency rescue program for hydrogen pipelines. In response this paper proposes a novel Optuna-improved back propagation neural network (Optuna-BPNN) to estimate hydrogen jet flame radiation. A linear integral approach incorporating leakage rate and jet flame length is theoretically derived to establish dataset for machine learning. Then the Optuna tool is employed to optimize the initial weights and thresholds of the BP neural network. Input matrix of the Optuna-BPNN model includes pipeline diameter leakage aperture size and hydrogen pressure. 8 sets of experimental data are employed to verify its correctness. When the abnormal data is excluded the predicted thermal radiation of hydrogen jet fire agrees quite well with experimental results with average and maximum deviations being 12.4% and 24.4% respectively. Using the linear integral approach 32670 thermal radiation data points are generated to train and test the Optuna-BPNN model. The maximum deviation between predicted and theoretical radiant heat flux for training and testing sets are only 4.5% and 6.2% respectively. Parallel comparison trials using 6 different machine learning algorithms show that the Optuna-BPNN model gives the best mean absolute error root mean square error and determination coefficient which proves the effectiveness and feasibility of the developed OptunaBPNN model in predicting thermal radiation of hydrogen pipeline jet fires.

Currently local regulations governing hydrogen installations vary by geographical region and by country leading to discrepancies in safety and separation distance requirements for similar hydrogen systems. This work carried out in the frame of IEA TCP H2 Task 43 (IEA TCP H2 2022) aims to provide an overview of various methodologies and recommendations established for risk management and consequence assessment in the event of accidental scenarios. It focuses on a case study involving industrial electrolyzers utilizing alkaline and PEM technologies. The research incorporates lessons learned from past incidents offers recommendations for mitigation measures reviews existing methodologies and highlights areas of divergence. Additionally it proposes strategies for harmonization. The study also emphasizes the most significant scenarios and the corresponding leakage sizes

In order to minimize emissions of the aerospace sector and thus its impact on the climate several novel concepts of propulsion systems for aircraft are being developed. Many of these concepts do not use an energy source based on the combustion of hydrocarbons but other means of energy generation and storage like hydrogen fuel cells and corresponding hydrogen storage systems. The use of hydrogen as a primary energy carrier in aircraft poses novel and different hazards when compared to conventional propulsion and fuel storage systems. The study described in the present paper identifies analyzes and evaluates failure conditions and corresponding hazards that are associated with the electrified propulsion systems. Mitigation strategies to prevent failures to occur or decrease their severity are recommended. The effects of the assessed failures on aircraft crew and occupants are classified as catastrophic hazardous or major as defined in the according Certification Specifications. Failure Conditions occurring at the aircraft system and subsystem levels are considered and their effect on the aircraft and propulsion system is assessed. The hazards identified mostly emerge due to the properties of the gaseous or liquid hydrogen. They include the flammability of gaseous hydrogen and the very low temperatures of cryogenic liquid hydrogen as well as the installation of high voltage power infrastructure and high capacity heat exchangers.