| Summary: | 碩士 === 長庚大學 === 機械工程學系 === 98 === Gas turbine engines fueled by hydrocarbon fuels have been used widely in power production for many years. Due to the shortage of hydrocarbon fuels and the demands of greenhouse gas emission reduction, hydrogen or hydrogen enrichment has already been considered or used as one of the most promising clean alternative fuels in the applications of engines. To better understand the combustion performance by adding hydrogen into natural gas fuel for a micro gas turbine, the combustion characteristics of a can type combustor has been modeled and the hydrogen addition effects were investigated. The simulations were performed using the commercial code STAR-CD, in which the three-dimension compressible k-ε turbulent flow model and presumed probability density function for chemical reaction between methane/hydrogen/air mixtures were used. The results showed the detailed flame structures including the flow fields, distributions of flame temperature, major species and gas emissions. In the parametric studies, the fuel injection velocities of hydrogen enriched natural gas were varied from 20 m/s to 60 m/s, and the amount of hydrogen was from 0% to 80% in mole fraction. The equivalence ratio changes when fuel inlet velocity and hydrogen amount increases. Addition of hydrogen can increase the combustion flame temperature and exit gas temperature, consequently the combustion efficiency. Further investigations of the combustor performance were made, including pattern factor, hot spots at exit, poor cooling locations, and pollutant emissions, to improve the combustor design for the micro gas turbine engine with hydrogen addition as an alternative fuel.
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