Experimental study on combustion of H2–CO–air mixtures in closed and vented vessels

Abstract

Experiments were conducted in two test facilities, a 0.25 m3 spherical vessel and a 60 m3 rectangular vented chamber, to examine the premixed combustion behavior of H2–CO mixtures. The study aims to provide data for the validation of models used for the assessment of combustion risks during postulated nuclear severe accidents and the use of syngas as an alternative fuel. The effects of fuel concentrations, molar ratio of CO/H2, initial gas temperature, steam concentration, and fan-induced turbulence on the flame dynamics are presented in this paper. The measurements are compared with literature data and predictions by empirical correlations. Within the range of the fuel concentration (≤15% in air) examined in this study, the results demonstrate that both the closed and vented combustion dynamics of H2–CO–air mixtures are similar to those of H2 only mixtures. The peak overpressures are always greater with more H2 in the mixture due to slower flame speeds of CO relative to H2. The combustion overpressures of H2–CO mixtures become similar to those of H2 mixtures when the fuel concentration is greater than what is required for downward flame propagation. The effect of fan-induced turbulence is much more pronounced for extremely lean mixtures.