Shock-induced Ignition Of Methane,Ethane And Methane/Ethane Mixtures Sensitized By NO₂

The nitrogen oxides released from combustion process of fossil fuels make a great impact on environmental safety and human health.Therefore,it is particularly important to develop clean energy and efficient combustion methods.As the main fossil fuel in the world,the natural gas abounds in coal beds.Methane and ethane are the main components of the natural gas.In the last decade,natural gas has been widely used in countries with abundant coal resources?the United States,Russia,Canada and China?as an alternative to oil.However,some by-products such as nitrogen oxide?NO_x?,sulfur oxide?SO_x?,carbon monoxide?CO?and carbon dioxide?CO₂?will be produced in the process of natural gas combustion.The presence of these by-products can make significant influence on internal combustion engine and gas turbine.Studies have shown that NO_x with low concentrations can also significantly reduce the ignition delay time of natural gas.Therefore,the research on the influence of NO_x on natural gas ignition provides a theoretical basis for how to realize the recycling of NO_x and improve the combustion efficiency of internal combustion engine and gas turbine.The content of this study is divided into four parts:1)Based on shock tube facility,the influence of NO₂ on the ignition of CH₄,C₂H₆ and CH₄/C₂H₆ has been studied.On the condition of temperature of 1021¹454 K,pressure of5¹6 atm,the ignition delay time has been measured with equivalent ratio of 1 and different NO₂ concentration?0%,25%,50%and 75%of fuel concentration respectively?.The experimental results show that the presence of NO₂ leads to significant reduction in ignition delay time of CH₄,and the reduction increases with increasing NO₂ concentration.The NO₂ promoting effect becomes more pronounced at high temperature part than low temperature part.With the contrastive analysis between some kinds of widely sued chemical reaction model and experimental data,the basis model is established using the model with the high conformance under various conditions.Meanwhile,the further correction of above model is made in order to to better predict ignition delay data.Using this model,the essential reason for the NO₂ promoting effect is showed by sensitivity analysis and path analysis.2)Based on shock tube facility,the infuence of different NO₂ concentration?0%,25%,50%and 75%of the C₂H₆ concentrations?on the ignition delay time of C₂H₆ with the equivalent ratio of 1 is studied on the condition of temperature of 1021¹454 K,pressure of 5¹6 atm.The experimental results show that the presence of NO₂ has the slight promoting effect on C₂H₆ compared with CH₄.And the promoting effect is more pronounced at low temperature than high temperature.The essential reason for the NO₂promoting effect on C₂H₆ is showed by sensitivity analysis and path analysis.3)Based on shock tube facility,the infuence of different NO₂ concentration?0%,25%,50%and 75%of the CH₄/C₂H₆ concentrations?on the ignition characteristics of natural gas?CH₄/C₂H₆?is studied on the condition of temperature of 1054¹734 K,pressure of 5¹6atm.The experimental results show that the presence of NO₂ has a significant promoting effect on the ignition delay time of CH₄/C₂H₆.And the promoting effect increases with increasing NO₂ concentration.The NO₂ promoting effect becomes more pronounced at low temperature part than high temperature part.The chemical kinetics reason for the NO₂promoting effect on CH₄/C₂H₆ is showed by sensitivity analysis and path analysis.4)The infuence of NO₂ on the ignition delay of CH₄,C₂H₆ and natural gas?CH₄/C₂H₆?is compared.The essential reason for the different influence of NO₂ on the ignition characteristics of CH₄ and C₂H₆ is showed by sensitivity analysis and path analysis.