Gaseq developed by Chris Morley and distributed free of charge, is the most interesting free combustion package that the author could find on the Internet.

It can calculate chemical equilibria involving ideal gases, for the following types of problems:

• equilibrium at given temperature and pressure

• calculating the temperature and the adiabatic composition at a given pressure

• equilibrium at a given temperature and at constant volume

• calculating the temperature and the adiabatic composition at a given constant volume

• adiabatic compression/expansion

• incident or reflected shocks and Chapman-Jouguet detonations

The figure below shows the GasEq calculation screen for the combustion of methane with air in slight excess.

EQS4WIN is a software package that solves a series of problems in the calculation of the equilibrium reaction and phase composition of complex chemical systems. It was written under the supervision of Dr. W. R. Smith.

EQS4WIN incorporates 30 years of research experience. A very restrained version can be downloaded for free.

The figure below shows the production of nitrogen oxides NOx at equilibrium, depending on the temperature during the stoichiometric combustion of methane.

In addition to its other features mentioned in another page, Thermoptim calculates many combustion taking place in energy cycles. It makes a variety of simplifying assumptions conventional in this context: in particular only the dissociation of CO2 can be taken into account, which precludes calculation of emissions of nitrogen oxides NOx, even at equilibrium.

In excess air, the complete non stoichiometric combustion of the fuel CHa with the atmospheric air can be written as a function of the air factor λ:

Thermoptim uses a generalized equation of this type, where the oxidant may be any compound gas comprising oxygen, and the fuel can either be given as CHa, or selected as one of the substances of the database.

A calculator allowing you to get acquainted with combustion calculations is available.

You will find below an overview of the screen of the calculator and the results it provides.

Finally, let us mention the CHEMKIN package (professional tool) aiming at facilitating the formulation, interpretation and resolution of problems involving chemical kinetics in gaseous and heterogeneous phases (gas-to-surface) in reactive flows, thus enabling the study of complex problems of combustion, catalysis, chemical vapor deposition and plasma etching. Developed by Sandia National Laboratories in the United States, ChemKin distributed by the company Reaction Design .

The www.jehar.com website also offers a number of online combustion computational tools, some of which seem quite attractive.