ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Principal component analysis, an advanced technique of sensitivity analysis, has been used to determine reduced mechanisms that can model species and temperature profiles in Plug Flow Reactors (PFR), Premixed Laminar Flames (PLF), and Perfectly Stirred Reactors (PSR) for two H2/air and two CH4/air mechanisms over a range of input parameters including initial temperature, equivalence ratio, and residence time. The results show that principal component analysis can be used effectively to reduce a comprehensive mechanism that contains unimportant reactions to a reduced mechanism that contains necessary and sufficient reactions. The accuracy of a reduced mechanism determined from principal component analysis can be easily controlled by carefully selecting reduction criteria. For the conditions chosen here, namely the requirement that radical profiles computed with reduced and comprehensive mechanisms agree to within 5%, substantial reductions were not achieved. Principal component analysis is able to resolve the influence of stoichiometry, combustor type, and mechanism on mechanism reduction.The two H2/air mechanisms were each reduced to mechanisms that can model all the cases considered, and the extent of reduction in each was very similar and modest. For H2/air chemistry, equivalence ratio had little effect on reduction. Combustor type was slightly more influential with the number of required reactions decreasing from PFR to PLF to PSR combustion. Relative to the H2/air system, principal component analysis of the CH4/air system is more difficult because of mechanism size. For CH4/air combustion, if we consider all equivalence ratios, PLFs require the most reactions, if individual equivalence ratios are examined, PFRs require the greatest number of reactions. Combustor type influences mechanism reduction substantially because of the different couplings between the fluid mechanics and chemistry. In H2/air combustion rich combustion required the fewest reactions and in CH4/air, it required the most. Reduction must be achieved by considering the entire mechanism since reactions interact in concert, for example, reactions unimportant in one CH4 mechanism are often important in the other. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 393-414, 1997.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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