Accidental combustion phenomena at cryogenic conditions

The presented state of the art can be intended as an overview of the current understandings and the remaining challenges on the phenomenological aspects involving systems operating at ultra-low temperature, which typically characterize the cryogenic fuels, i.e., liquefied natural gas and liquefied hydrogen. To this aim, thermodynamic, kinetic, and technological aspects were included and integrated. Either experimental or numerical techniques currently available for the evaluation of safety parameters and the overall reactivity of systems at cryogenic temperatures were discussed. The main advantages and disadvantages of different alternatives were compared. Theoretical background and suitable models were reported given possible implementation to the analyzed conditions. Attention was paid to models describing peculiar phenomena mainly relevant at cryogenic temperatures (e.g., para-to-ortho transformation and thermal stratification in case of accidental release) as well as critical aspects involving standard phenomena (e.g., ultra-low temperature combustion and evaporation rate).