Methane has a narrow range of flammable limits,low flame speed and poor ignition characteristics,which limit its utilization in internal combustion engines.However,this issue can be remedied through the use of CH_(4)/...Methane has a narrow range of flammable limits,low flame speed and poor ignition characteristics,which limit its utilization in internal combustion engines.However,this issue can be remedied through the use of CH_(4)/DME blends,because DME has better ignition and combustion characteristics.In this study,the effects of pressure and blending ratio on the combustion characteristics of CH_(4)/DME blended fuels were investigated by using a high-pressure diffusion counterflow system,a constant volume combustion bomb,and CHEMKIN software.The reaction pressures are 0.1 MPa,0.2 MPa,0.3 MPa,and the blending ratios are 100%DME,75%DME+25%CH_(4),50%DME+50%CH_(4)and 25%DME+75%CH_(4)(mol%).The results show that the laminar flame speed,flame temperature,and extinction limit of CH_(4)/DME blended fuel decrease as the CH_(4)blending ratio or pressure increases.CH_(4)addition and increasing pressure both lead to the competition for OH and H radicals between CH_(4)and DME.However,the increase of CH_(4)mole fraction can also increase the path flux of CH_(4)+H=CH_(3)+H_(2),while the increase of pressure can decrease this path flux.Moreover,increasing pressure can promote all reaction processes and reaction rates.展开更多
基金the support from the Fundamental Research Funds for the Central Universities(30919012104)the National Key R&D Program of China(2016YFB0600100)。
文摘Methane has a narrow range of flammable limits,low flame speed and poor ignition characteristics,which limit its utilization in internal combustion engines.However,this issue can be remedied through the use of CH_(4)/DME blends,because DME has better ignition and combustion characteristics.In this study,the effects of pressure and blending ratio on the combustion characteristics of CH_(4)/DME blended fuels were investigated by using a high-pressure diffusion counterflow system,a constant volume combustion bomb,and CHEMKIN software.The reaction pressures are 0.1 MPa,0.2 MPa,0.3 MPa,and the blending ratios are 100%DME,75%DME+25%CH_(4),50%DME+50%CH_(4)and 25%DME+75%CH_(4)(mol%).The results show that the laminar flame speed,flame temperature,and extinction limit of CH_(4)/DME blended fuel decrease as the CH_(4)blending ratio or pressure increases.CH_(4)addition and increasing pressure both lead to the competition for OH and H radicals between CH_(4)and DME.However,the increase of CH_(4)mole fraction can also increase the path flux of CH_(4)+H=CH_(3)+H_(2),while the increase of pressure can decrease this path flux.Moreover,increasing pressure can promote all reaction processes and reaction rates.
