Hydrogen mitigation assisted by catalytic conversion under oxygen-limited conditions

Hydrogen (H2) accumulation in confined areas can pose a threat to the structure's integrity in case of an undesired ignition. Therefore, mitigation measures are critical in preventing such devastating accidents. Passive Autocatalytic Recombiners (PARs) are defined as safety devices developed for preventing H2 accumulation in confined environments. During PARs operation, the ambient oxygen (O2) concentration decreases due to the H2 reaction on the catalyst surface, possibly reaching oxygen-limited conditions. In this work, a 2D transient numerical model was validated against experiments conducted at low O2 dilution ratios. After validation, the model was also verified by comparing the results with numerical simulations from literature. It was found that oxygenlimited conditions occurred due to low O2 concentrations at the catalyst surface. At these conditions, H2 was not entirely recombined, decreasing the PAR efficiency. This indicates that in case of a H2 release in a confined space, oxygen-limited conditions would cause H2 accumulation due to limited PAR operation, increasing the risk of an undesired ignition.