Computational Fluid Dynamics Simulation of Steam Reforming and Autothermal Reforming for Fuel Cell Applications
With the increasing demand for fuel cell applications in transportation, the performance of reformers using gasoline or diesel as the fuel needs to be optimized. Numerical models based on computational fluid dynamics (CFD) were used to simulate the performance of these reformers. A CFD model of steam reforming and a CFD model of autothermal reforming were developed and validated for two reformers. Each model included submodels for the reactor and reaction chemistry. A single channel was used in the model of steam reforming and a whole reactor was modeled in the model of autothermal reforming. A reaction rate expression was developed for the steam reforming reaction to form hydrogen and carbon dioxide. The CFD results provided an adequate match to the experimental data from the literature. The percentage of difference between each experimental measurement of the mole fraction of hydrogen and the corresponding CFD prediction was less than 17.7% for the model of steam reforming and 16.8% for the model of autothermal reforming. The CFD models were used to predict reformer performance. For steam reforming, the inlet steam-to-carbon molar ratio had a negligible effect on reforming efficiency when it was varied from 2 to 4. The reforming efficiency decreased slightly as the inlet velocity was increased from 2.9 to 8.7 m/s, which was mainly caused by the steam reforming reaction. For autothermal reforming, the thermal conductivity of the catalyst support affected the temperature profile in the reactor, but its effect on the mole fraction of hydrogen in the products was negligible. The reforming efficiency decreased by 11.5% as power input was increased from 1.7 to 8.4 kW.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:steam reforming autothermal cfd modeling fuel processing cells
Date of Publication:04/27/2009