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Simulation of hydrogen mitigation in catalytic recombiner: Part-I: Surface chemistry modelling

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Title Simulation of hydrogen mitigation in catalytic recombiner: Part-I: Surface chemistry modelling
 
Creator PRABHUDHARWADKAR, DM
AGHALAYAM, PA
IYER, KN
 
Subject COMBUSTION
MIXTURES
PLATINUM
IGNITION
CONTAINMENTS
FLAT
 
Description This paper aims at accurate modelling of a Passive Catalytic Recombiner used for hydrogen mitigation in the nuclear power plant containments. In order to assess the performance of the recombiner through numerical simulations, it is required to accurately predict the catalytic reactions. There are various detailed reaction mechanisms available in the literature for prediction of hydrogen-oxygen reaction over a platinum surface. While a single step reaction rate expression is always sought in order to obtain numerical predictions economically, a detailed reaction mechanism that includes several elementary reactions and intermediate species is likely to produce more accurate predictions. The paper compares the solution from two of competing models, one a single step reaction and the other a multiple reaction model. A new single step rate expression is also derived from the detailed mechanism after simplifying it for the present problem. The paper also considers the diffusion controlled model that assumes rapid reaction rates for which the surface chemistry is not required at all. In order to find the best suited approach to model the surface chemistry, CFD simulations were performed with FLUENT code using available experimental data from the literature. The current study reports comparison up to 4% H(2) mole fraction in dry air with catalyst temperature varying from 300 K to 800 K. It is demonstrated that the new single step model is able to satisfactorily predict the data as well as the detailed chemistry model. The diffusion controlled model is shown to over-predict the data. (C) 2010 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE SA
 
Date 2012-06-26T07:43:10Z
2012-06-26T07:43:10Z
2011
 
Type Article
 
Identifier NUCLEAR ENGINEERING AND DESIGN,241(5)1746-1757
0029-5493
http://dx.doi.org/10.1016/j.nucengdes.2010.09.032
http://dspace.library.iitb.ac.in/jspui/handle/100/14165
 
Language English