The Gas Research Institute (GRI) is a consortium that showed concern towards developing a set of chemical reaction mechanisms specifically tailored to model natural gas combustion. GRI-Mech 3.0 is an optimization mechanism of the consortium (GRI) that succeeds version 2.11. It is based on both experimental and computational research in flame speed, ignition delay, and species profile.

GRI-Mech 3.0 operate optimally at a pressure range of 10 Torr – 10 atm (Note: 1 atm = 101325 Pa = 760 Torr), temperature range of 1000 – 2500 K, and at equivalent ratios from 0.1 – 5 for premixed systems. However, it should be noted that NOx and CO2 emissions peaked near an equivalent ratio of 1, while CO will continue increasing provided that equivalent ratio increases. Furthermore, NOx is greatly reduced by lowering the peak combustion temperature, while CO emissions usually respond least to pressure and temperature variations. In addition, minimum NOx and CO2 usually occur at lean and rich conditions respectively.

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