Laminar Flame Speeds of Moist Syngas Mixtures

Authors:   A. K. Das, K. Kumar, and C. J. Sung

Direct link to the paper:


This work experimentally investigates the effect of the presence of water vapor on the laminarflamespeeds of moistsyngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngasmixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminarflamespeed is demonstrated. The experimental laminarflamespeeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminarflamespeed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminarflamespeed due to water addition. On the other hand, for higher values of H2/CO ratio the laminarflamespeed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H2 + OH = H2O + H is worth revisiting and refinement of binary diffusion coefficient data of N2–H2O, N2–H2, and H2–H2O pairs can be considered.

Citation:   A. K. Das, K. Kumar, and C. J. Sung, “Laminar Flame Speeds of Moist Syngas Mixtures,” Combustion and Flame 158 (2), 345-353 (2011).