Stability and Burning Velocities of Laminar Carbon Monoxide-Air Flames at Pressures up to 93 Atmospheres

Abstract

Bunsen-burner flames of carbon monoxide-air mixtures were investigated at ambient pressures up to 93 atmos. The experiments show that the critical velocity gradients at the burner tube wall for flash-back increase with pressure whereas the burning velocities decrease when the pressure is raised. However, in a previous investigation it was found that the burning velocities of hydrogen-oxygen flames increase with pressure. It is concluded that the burning velocities of carbon monoxide-air flames decrease with rising pressure because the rate of diffusion of active particles into the unburned gas is reduced with pressure while no increase in heat transfer occurs. In hydrogen-oxygen flames the rate of heat transfer increases because the flame temperatures are higher at elevated pressures because of the reduction in the degree of dissociation.