Numerical Study on Counterflow Diffusion Flames of Natural Gas with CO2 Dilution

Since natural gas has become a very important energy source in most parts of the industrialize world, it is necessary to study the flame structure and the effect of its exhausts on the environment. In this paper, the combustion of natural gas, which is a combination of different hydrocarbons such as CH4, C2H6,and C3H8, and gasses like N2, CO2, and O2 and H2 has been investigated using the counterflow diffusion flame model. In this research, the profiles of temperature, species concentration, and NOx mixtures are determined using numerical solution and the CO2 diluent effect on temperature distribution and rate of species production are investigated. GRI3.0 mechanism is selected as the chemical kinetic in modeling natural gas combustion. Increasing the CO2 diluent in the fuel causes a reduction in the peak combustion temperature, which is caused by decreased concentration of reactants and consequently reduction in the general reaction rate. It also reduces the peak of mole fraction species of C2H2 and NO.