Ignition of methane and propane in high-temperature oxidizers with various oxygen concentrations

In this investigation, ignition processes of methane (CH4 > 98%) and propane (C3H8 > 95%) using a high-temperature oxidizer (Toxi > Tai) with a varying oxygen concentration (zO2=0.05÷0.21zO2=0.05÷0.21), applying two types of experimental installations, viz. a constant–volume bomb (CVB) and a co-flow reactor (CFR) were investigated. The influence of the initial temperature of the oxidizer (for methane Toxi = 960 ÷ 1234 K and for propane Toxi = 803 ÷ 1055 K), the equivalence ratio and oxygen concentration in the oxidizer on ignition of gaseous fuels is analyzed and discussed. It is shown that in order to achieve an effective reaction of ignition (taking into account the minimum value of ignition delay time τig and maximal value of the increment of temperature ΔT) the oxidizer temperature need not be maximized. There are optimal values of temperature of the oxidizer (for methane Toxi ≈ 1100 K and for propane Toxi ≈ 950 K) in which the parameters mentioned above reach their extreme values.