Derivation of Le Chatelier's mixing rule for flammable limits
Article first published online: 16 APR 2004
Copyright © 2000 American Institute of Chemical Engineers (AIChE)
Process Safety Progress
Volume 19, Issue 2, pages 112–117, Summer 2000
How to Cite
Mashuga, C. V. and Crowl, D. A. (2000), Derivation of Le Chatelier's mixing rule for flammable limits. Proc. Safety Prog., 19: 112–117. doi: 10.1002/prs.680190212
- Issue published online: 16 APR 2004
- Article first published online: 16 APR 2004
In 1891 Le Chatelier  first proposed an empirical mixing rule for predicting the flammable limit of lean fuel air mixtures -this method is still widely used today. This paper presents a proof to Le Chatelier's mixing rule based on thermodynamics. A number of assumptions are required to produce the proof. These assumptions are
The product heat capacities are constant.
The number of moles of gas is constant.
The combustion kinetics of the pure species are independent and unchanged by the presence of other combustible species.
The adiabatic temperature rise at the flammability limit is the same for all species.
These assumptions we re found to be reasonably valid at the lower flammability limit and less so at the upper flammability limit.
This paper also considers experimental data that support some of the assumptions made to arrive at the Le Chatelier mixing equation.