Technical Report 112, c4e-Preprint Series, Cambridge

Using timescale analysis for optimising large chemical kinetic reaction mechanisms

ref: Technical Report 112, c4e-Preprint Series, Cambridge

Associated Theme: Numerics

Abstract

A novel chemical kinetic diesel surrogate model is introduced. The model consists of chemistry for each main chemical group in diesel fuel: n-decane, 2,2,4,4,6,8,8-heptamethylnonane, methylcyclohexane, and toluene. Ethanol chemistry is also included should the effect of oxygenates on conventional diesel fuels need to be investigated. This kinetic model is optimised using an automatic optimisation procedure and a novel heuristic for selecting reactions useful in optimisation is introduced. This heuristic combines the Level of Importance (LOI) algorithm and reaction sensitivity analysis to select the most relevant reactions for optimisation, thus including the importance of timescales in optimization, which has previously not been the case. It greatly reduces the time needed to select reactions for optimisation, and furthermore identifies those that would be otherwise ignored. Error analysis is performed on the optimised chemical kinetic mechanism and shows that the optimisation improves its overall response when compared to a wide range of experimental data.

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