Effects of Preheating Temperature and Fuel-Air Equivalence Ratio on Pollution Control in Hydro Carbon Combustion

Burning fossil fuels produces a great part of our energy production today and probably it will still do for at least the next few decades. Combustion is encountered in many practical systems such as heaters, power plants, aeronautic engines, buildings, etc. The growing expectations on increasing efficiency and reducing fuel consumption and pollutant emissions make the design of combustion systems much more complex and the science of combustion a rapidly expanding field. Comprehension and analysis of complex physical mechanisms start with the study and control of temperature and species in flame is an important challenge for industrial and environmental issues. We focus our study on a Kerosene, Methane and Gasoil flame simulated with detailed chemistry. The mathematical model is based on the enthalpy conservation between two states, and this model is used with the first law of thermodynamics to define enthalpies of reaction and adiabatic flame temperatures at constant pressure [1, 4]. To reach this objective, we must know the products of complete hydrocarbon combustion and all species of combustion products after dissociation and their molar fractions and equilibrium equations of dissociation reactions. Also, we calculate the elementary equilibrium reactions enthalpy and entropy by using (Bonni Mc Bride et al.) coefficients [2, 3] to compute thermodynamic functions such as specific heat, enthalpy and molar entropy. The obtained system of equations is resolved by Newton Raphson method. Among the obtained results are: To reduce the pollutants (CO2 , CO) and the fuel consumption, the mixture of fuel-air must be lean, therefore, the equivalence ratio must be lower than the unit. According to this study, if the fuel consumption is reduced via the equivalence ratio from 1.1 to 0.95, the combustion temperature remains constant, however, the production of CO will be reduced by 25%.

Keywords: Adiabatic flame temperature, Combustion, Fuel-Air equivalence ratio, Hydrocarbon, Pollution, Preheating.