| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 90 === Abstract
Fuel Cell generally becomes the pronoun of new and clear power. Among different types of fuel cells, the PEM Fuel Cell (PEMFC) is the most mature in technology. The fuels for the PEMFC are hydrogen and oxygen. Oxygen can be obtained from air, but the hydrogen must be derived from metal hydrides or from the reforming product. When metal hydride is used as the source of hydrogen, the storage density of hydrogen is low and it is not convenient to refill. The reforming reaction to generate hydrogen is an alternative choice. Different reforming reactions are developed with different fuels. As a liquid fuel for producing hydrogen, methanol has many advantages, such as low steam to carbon ratio, low reforming temperatures (250~350℃), high quality (sulfur <5 ppm), ease of storage and transportation.
To further understand the characteristics of the methanol reformer, a tube-type methanol reformer is designed (Length: 420mm, inner diameter: 44mm) with the commercial catalyst G66B in this experiment. Methanol and water are sent to the vaporizing section by the liquid pump, and then sent to the methanol reformer after the vaporizing process. Premixing with the air is performed in the preheating section of the methanol reformer and the mixture is heated to the required reacting temperature before entering the reaction section. The reforming product then passes through the cooler system where the resident water and methanol will be condensed out. Part of product gas is further sent to the GC to analyze the species of the gas. In this study, effects of experimental parameters of the design methanol reformer, such as steam-to-methanol mole ratio (S/C), oxygen-to-methanol mole ratio (O/C), reacting temperature and feeding rate, are investigated and the performance of the methanol reformer is evaluated.
The result of the designed methanol reformer works well. In the experiment results, about the methanol steam reforming reaction, controlling the S/C at 1.2, 1.8, and 2.0, S/C=1.8 is the best feeding condition among these experiments. In the comparison experiment between the methanol steam reforming reaction and the methanol autothermal reforming reaction, it appears that the latter is obviously more suitable for the methanol reformer. About the methanol autothermal reforming, controlling the O/C at 0.2 is a better feeding condition. At S/C = 1.8, O/C = 0.2, feeding rate = 6ml/min, and reaction temperature = 350℃, the maximum rate of hydrogen generation is about 0.145 mole/min, which is equivalent to a 260-Watt power output of the PEM Fuel Cell; meanwhile, the carbon-monoxide mole concentration is about 2.45%.
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