Conversion of hydrocarbon fuels, such as gasoline, methanol, and diesel fuel by reforming is an attractive alternative for onboard production of hydrogen to reduce vehicular emissions. The successful development of a fuel cell-powered vehicle depends on the development of a reliable fuel processor. Partial oxidation (PO), steam or CO2 (dry) reforming (SR or DR), or autothermal reforming (ATR) are the chemical reactions considered for hydrocarbon reforming. The choice of the reaction in the fuel processor depends on the operating characteristics of the application (like varying power demand, rapid startup, frequent shutdowns) and the type of fuel cell stack (PEMFC or SOFC). ATR becomes the best option since the combustion of some of the fuel supplies the energy required for the reforming reaction and better sulfur tolerance than SR. Additionally, the water gas shift reaction, which proceeds simultaneously, reduces the CO content of the hydrogen-rich gas; also, the methane content of the gas is lower than the other methods. Faster startup time and better transient response are the other advantages of ATR, which can be attained by tuning the feed stoichiometry. ATR reactors are smaller, quick-starting and faster-responding than SR reactors, and give higher hydrogen concentration. The most important operation variables for ATR are temperature, pressure, oxygen/carbon ratio, steam/carbon ratio, equivalence ratio, the catalyst, and space velocity. The values of these variables are selected to minimize the carbon formation on the catalyst and methane production. The higher the steam/carbon ratio, the higher is the hydrogen yield, but higher the energy requirement. The lower the steam/carbon ratio, the higher is the formation of CO oxidation due to partial oxidation. This discussion indicates that the operation variables have to be optimized. The present study has been undertaken in order to investigate the effect of operation variables on the ATR of dodecane and hexadecane, which are selected as diesel surrogates. The main objective is to perform simulation on a fuel reforming process to delineate the most important operating variables for the process so that the optimum conditions may be selected. For this purpose, the chemical reaction software, CHEMKIN, is used. A basic flowchart for ATR is selected and a design basis is determined. The main operating variables are oxygen to carbon molar ratio (O2/C), water to carbon molar ratio (H2O/C) and exit reformer temperature; but, the latter is dependent on the former two variables. The optimum values of these variables depend on both thermodynamics and design. The simulation results will be presented in this paper.

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