| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 101 === Chemical kinetics of hydrogen production from the thermocatalytic decomposition (TCD) of methane is modeled in this study. Numerical simulations are carried out to figure out the detailed reaction phenomena in a catalyst bed. TCD of methane is a noticeable route to produce hydrogen without the formation of CO and CO2. This study is separated into two parts. One is TCD of methane with conventional heating, and the other is TCD of methane with microwave heating. At the first part, chemical kinetics of hydrogen production from the TCD of methane at the early reaction stage and the steady state with conventional heating is modeled. The effects of reaction (wall) temperature, catalyst mass, and reactant flow rate on the performance of methane TCD are evaluated. The predictions suggest that the CH4 conversion is linearly proportional to the reaction temperature at the early stage; the reaction is more sensitive to the reaction temperature at the steady state. Hydrogen formation from the reaction is also affected by the flow rate to a certain extent. In contrast, the performance of methane TCD is relatively insensitive to the catalyst mass, regardless of which reaction stage is. When the temperature distribution, reaction rate, and H2 concentration in the catalyst bed are examined, two-dimensional contours of reaction rate are exhibited, whereas the isothermal and concentration contours are almost one-dimensional.
At the second part, to recognize the characteristics of interaction of methane TCD and microwave irradiation in an activated carbon catalyst bed, the chemical reaction along with microwave-assisted heating is modeled and simulated numerically. The influences of two important factors, namely, the supplied power and volumetric hourly space velocity (VHSV), on the performance of methane TCD are investigated. The predictions suggest that a higher power supply can efficiently promote the performance of methane TCD. Increasing VHSV reduces the CH4 conversion, but more hydrogen is produced.
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