What is Air ratio?
How many times the minimum (stoichiometric) amount of air is actually supplied to burn the fuel.
Boilers and furnaces run with a little extra air to avoid unburnt fuel. Too much extra air carries heat away in the flue gas, so the air ratio is closely controlled.
\lambda = 1.2 means 20 % more air than the stoichiometric amount.
Compositions are entered directly for now; building a composition from an air ratio is planned.
\lambda = \frac{A}{A_{\mathrm{st}}} = \frac{1}{\varphi}
Some texts use other symbols for the same quantity (for example m in Japanese practice).