Recent Progress in Hydrogen Flammability Prediction for the Safe Energy Systems

Abstract

Many countries consider hydrogen as a promising energy source to resolve the energy challenges over the global climate change. However, the potential of hydrogen explosions remains a technical issue to embrace hydrogen as an alternate solution since the Hindenburg disaster occurred in 1937. To ascertain safe hydrogen energy systems including production, storage, and transportation, securing the knowledge concerning hydrogen flammability is essential. In this paper, we addressed a comprehensive review of the studies related to predicting hydrogen flammability by dividing them into three types: experimental, numerical, and analytical. While the earlier experimental studies had focused only on measuring limit concentration, recent studies clarified the extinction mechanism of a hydrogen flame. In numerical studies, the continued advances in computer performance enabled even multi-dimensional stretched flame analysis following one-dimensional planar flame analysis. The different extinction mechanisms depending on the Lewis number of each fuel type could be observed by these advanced simulations. Finally, historical attempts to predict the limit concentration by analytical modeling of flammability characteristics were discussed. Developing an accurate model to predict the flammability limit of various hydrogen mixtures is our remaining issue.

Enhancing the Chemo-Enzymatic One-Pot Oxidation of Cyclohexane via In Situ H2O2 Production over Supported Pd-Based Catalysts

“…Note 2: reaction conditions used within this study operate outside the flammability limits of gaseous mixtures of H 2 and O 2 …”

“…Note 2: reaction conditions used within this study operate outside the flammability limits of gaseous mixtures of H 2 and O 2 . 23 Note 3: the conditions used within this work for H 2 O 2 synthesis and degradation using high-pressure batch conditions have previously been investigated, with the presence of CO 2 as a diluent for reactant gases and a methanol co-solvent in the case of the high-pressure experiments identified as key to maintaining high catalytic efficacy toward H 2 O 2 production. 22 Direct Synthesis of H 2 O 2 from H 2 and O 2 , Under High-Pressure Batch Conditions.…”

Fire Safety Evaluation of High-Pressure Ammonia Storage Systems

“…Three detailed reaction mechanisms (GRI 3.0, Nakamura, Okafor) [20][21][22] were adopted to compare and examine closely the flame structure, flammability limits, and combustion characteristics. The optically thin model [23] was used to apply radiation heat loss from CO 2 , CO, CH 4 , and H 2 O.…”

“…Here, Nakamura and Okafor mechanisms derive similar values, while HRR values of GRI are relatively low. Since the GRI mechanism is designed exclusively for CH 4 fuel, the chemical reactions of hydrocarbon fuels are well predicted [20]; however, the prediction rate is significantly lower for nitrogen hydrides. On the other hand, in the case of Nakamura and Okafor mechanisms, exclusively designed ammonia fuel [21,22], the prediction rate is relatively higher than that of GRI, and the calculation results of both mechanisms are very similarly derived.…”

Study on nitrogen barrier protection of an airend oil-free compressor bearings in H2 compression

“…From the ATEX point of view, the lower flammable limit for O2 concentration in H2 and pure O2 mixture is about 4.65% in pure oxygen [7], and in air about 4.0% [7,8]. In the literature, flammability limits and burning velocities of gaseous mixtures containing hydrogen have been measured to reach temperatures up to 250°C and pressures up to 4 MPa [9].…”