Measurement and correlation of laminar flame speeds of CO and C2 hydrocarbons with hydrogen addition at atmospheric and elevated pressures

The laminar flame speeds of mixtures of ethane, ethylene, acetylene, and carbon monoxide with small amount of hydrogen addition at atmospheric and elevated pressures were experimentally and computationally determined. It was found that the approximate linear correlation identified previously between the laminar flame speeds and an appropriate definition of the amount of hydrogen addition for methane, propane and n-butane at atmospheric pressure also largely applies to ethane, ethylene, and acetylene at atmospheric as well as elevated pressures. The linear correlation, however, does not hold for carbon monoxide, at all pressures, due to the strong catalytic effect of hydrogen on the oxidation of carbon monoxide. A mechanistic analysis shows that both the Arrhenius and diffusive contributions to the laminar flame speed are nearly linear functions of the hydrogen addition, which explains this overall approximate linear correlation.

► Experiment shows flame speeds of hydrocarbons vary linearly with H2 addition.
► The linear relation was also shown to hold at elevated pressures up to 20 atm.
► The linearity is mainly due to kinetic contribution of H2 on fuel oxidation.
► Linearity does not hold for CO due to strong catalytic effect of H2 on CO.