| Summary: | 碩士 === 國立成功大學 === 太空與電漿科學研究所 === 102 === Hydrogen is a long-term green energy solution. In the thesis, we describe a plasma method for decomposing methane or propane molecules into hydrogen molecules and carbon particles. The plasma discharge is generated by applying a pulsed high voltage to the electrode immersed in the methane or propane gas inside a dielectric barrier discharge (DBD) reactor. We investigate the hydrocarbon gas decomposition efficiency and hydrogen production by using different types of electrodes and different waveforms (pulse width and repetition rate) of high voltage pulses. The ceramic based DBD is the stable and most efficient electrode for decomposition. For producing discharges, high voltage pulses with width 5-30 μs and the pulse repetition rate of 4 kHz and maximum voltage amplitude of 13 kV are employed. The decomposition rate is observed to depend on the pulse width applied to DBD electrode. The present high voltage power source used in the experiments does not produce good waveform. If the pulse width is more than 10 μs, the pulse is distorted by multiple oscillation. As an example, a voltage pulse with 20 μs width has four ~5μs oscillations superposed on the voltage pulse, and thus for longer pulse width there are also more plasma discharges and the decomposition rate increases. However, for pulse width longer than 20μs the decomposition rate decreases. At present, the pulse with 20 μs pulse width shows the best efficiency for decomposition. The experimental results show that the decomposition depends on the input pulse width, which is related to the lifetime of plasma produced by each pulse. At present we have achieved the result that it requires approximately 0.33 kWh input energy to produce 1 mole of Hydrogen.
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