2D CFD Studies of Passive Catalytic Recombiner for H₂ Mitigation

ABSTRACT

Resolving hydrogen related safety issues, pertaining to nuclear reactor safety have been an important area of research world over for the past decade. The studies on hydrogen transport behavior and development of hydrogen mitigation systems are still being pursued actively in various research labs, including Bhabha Atomic Research Centre (BARC), in India. The passive catalytic recombiner is one of such hydrogen mitigating device consisting of catalyst surfaces arranged in an open-ended enclosure. In the plate type recombiner design sheets made of stainless steel and coated with platinum catalyst material are arranged in parallel inside a flow channel. The catalyst elements are exposed to a constant flow of a mixture of air, hydrogen and steam. In the presence of hydrogen with available oxygen, a catalytic reaction occurs spontaneously at the catalyst surfaces and the heat of reaction produces natural convection flow through the enclosure. Numerical simulation and experiments are required for an in-depth knowledge of such plate type passive catalytic recombiner. Specific finite volume based in-house CFD code has been developed to model and analyse the working of these recombiner. 2D CFD computations have been performed to study the mechanism of catalytic recombination and have been used to simulate one literature quoted experiment. Parametric study has been performed for particular recombiner geometry for various inlet conditions. Salient features of the simplified CFD model developed at BARC and results of the present model calculations are presented in this paper.

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