The Effects Of CO₂ On The Laminar Flame Speed Of C1-C3 Alkanes In O₂/CO₂ Atmospheres

Oxy-fuel or O₂/CO₂ recycle combustion is a highly interesting option for CO₂capture and storage,due to the possibility of industrialization.Laminar flame speed,one of the key characteristics that determines the propagation of one-dimensional,planar,and adiabatic premixed flames,is used to evaluate detailed kinetic models.Therefore,this paper studied in detail the effects of CO₂ on alkane?C1-C3?laminar flame speed in premixed flame.Experimentally,flames were established in the counterflow configuration at atmosphere pressure with inlet temperature?T_u?of 293K?methane?,285K?ethane?,285K?propane?and the laminar flame speed?⁰?in O₂/CO₂ atmosphere was measured with the help of PIV technique.The results showed that the laminar flame spped in O₂/CO₂ atmospheres were slower than that in O₂/N₂ atmosphere dramaticlly.Numerically,a modified mechanism HUST-1 involving 170 species and 1208 reactions for the oxy-fuel combustion mode was proposed and validated by experimental results from the literature.The agreement between the experimental results and the numerical calculations was satisfactory.A comprehensive comparison between the flame speeds in O₂/CO₂ atmosphere and O₂/N₂ atmosphere with an identical mole fraction of O₂ is established by introducing the artificial materials U,V,W,X,Y to gradually isolate the effects of chemical properties and specific heat,mass diffusivity,radiation,thermal conductivity.The results showed that the reasons of the decline in speed in O₂/CO₂ atmosphere were mainly chemical properties and specific heat of CO₂.The high concentration in CO₂ led to the dramatic decline of laminar flame speed in O₂/CO₂ atmospheres.What's more,the high concentration in CO₂caused a tremendous decline in the reaction speed of CO+OH<=>CO₂+H.In addition,the reactions that contribute to the rise of flame speed decreased to a much high degree than the ones that restrain the flame speed.