Unifying definition of the local equivalence ratio for complex mixtures and the concept of bonding fraction
Year: 2025
Type: article
Abstract: New combustion systems with increasingly complex fuels and mixing processes require that the basic definitions of equivalence ratio are questioned and made universal to avoid any ambiguity in its use. This work presents a way of computing the equivalence ratio for virtually any mixture using a local atomic balance inspired by the literature work. The present framework is made to be generic, universal and chemically accurate. The methodology is detailed and its adaptation to any mixture involving diverse atoms and separate phases is presented. The normalised equivalence ratio is also presented as an other kind of mixture faction, called bonding fraction, highlighting common behaviours in the combustion of oxygenated and non-oxygenated hydrocarbons in counter-flow diffusion flames. Finally, it is shown that this universal method is more chemically realistic when handling mixtures with reducers and oxidisers belonging to the same molecule and for dual-fuel systems where an assumption has to be made. While this work's equivalence ratio definition is suggested to replace the classical one as the only chemically relevant, the bonding fraction is not meant to replace the mixture fraction but to be a new quantity for the analysis of complex mixtures.
Source: Combustion Theory and Modelling
Author: Quentin Cazères
Institutions: University of Cambridge, Sorbonne Université
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4407551611