Study on Combustion Characteristics ofHydrogen- Methane Coaxial Jet Diffusion Flames

• Main Authors: Shun-Shian Wang, 王舜賢
• Other Authors: Shuhn-Shyurng Hou
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/83503114333173287314

碩士 === 崑山科技大學 === 機械工程研究所 === 100 === This study aimed at investigating the combustion characteristics of hydrogen/methane hybrid fuel jet diffusion flames. The influence of hydrogen addition and co-flow air on flame stability, flame appearance, flame height, liftoff height, flame radiation and emissions was conducted. First, for the free jet diffusion flames, it was found that hydrogen addition sustained a progressive improvement in flame stability (including liftoff, blowout and blowoff) and reductions in flame height and lifoff height. With increasing fuel velocity or decreasing hydrogen concentration, radiative heat transfer rate (radiative heat flux) increased for a fixed radial direction distance 50 cm. The results of flame height measurements agree well with those of empirical correlation formula proposed by Roper (1977) and Altenkirch (1976). Second, for the hydrogen-methane coaxial jet diffusion flames, with an increase in hydrogen content, flame height and lifoff height were shortened. However, with increasing co-flow air velocity, flame height decreased but lifoff height increased. The critical velocities corresponding to liftoff, blowout or blowoff increased as the hydrogen content was higher in the hydrogen-methane blend. That is, the flame stability was widened as the hydrogen content was raised. With increasing co-flow air velocity or hydrogen concentration, radiative heat transfer rate (radiative heat flux) decreased for a fixed radial direction distance 50 cm at a constant fuel velocity of 12m/s. Additionally, with an increase in co-flow air velocity, the CO2 and NOx emissions increased, but the CO emission decreased