Numerical modelling of catalytic hydrogen combustion in passive autocatalytic recombiners: A review

Nuclear energy appears to be a promising technology to replace fossil fuels in the foreseeable future. It is therefore important to develop accurate numerical models to ensure safe operation of nuclear power plants, especially during severe accident scenarios. Passive Autocatalytic Recombiners are currently employed to mitigate hydrogen explosions during accidents. Numerical modelling of Passive Autocatalytic Recombiners remains a multidimensional and Multiphysics problem that involves simulation of fluid dynamics, hetero-, and homogeneous chemistry, heat, and mass transport, and various necessary details in order to obtain reliable results. However, it is significant to outline the fundamental components of PAR modelling. This paper summarises the most popular approaches to PAR modelling and compares various studies to identify the differences and also highlights the similarities. This summary clearly shows the trends of the most recent development on the topic and identifies gaps for future work. Thus far, various models have been developed for steady state, low inlet hydrogen concentration (∼4%), low flow (velocity is ∼1 m/s), dry air, and, only a few studied oxygen starvation and carbon monoxide poisoning. These models have proven to be accurate in the first approximation and have been validated by various test facilities. Nonetheless, there is still a large scope in developing models for transient and start-up behaviour, ignition criteria, other catalyst types, and higher hydrogen concentrations, temperatures, and pressures. These conditions are typical of accident scenarios at nuclear power plants and are therefore vital to predict accurately.