Chemical Effects of Carbon Dioxide Addition on Dimethyl Ether and Ethanol Flames: A Comparative Study
2015
Liu, Dong
The chemical effects of CO₂ addition on premixed laminar low-pressure dimethyl ether and ethanol flames were studied by comprehensive numerical analysis from fuel-lean to fuel-rich conditions. Added CO₂ is assumed as normal reactive CO₂ and fictitious inert CO₂ to assess the chemical effects of CO₂. The dilution and thermal effects of CO₂ addition decrease C₂H₂ mole fractions in ethanol flames instead of DME flames, but the chemical effects can reduce C₂H₂ mole fractions in both DME and ethanol flames at all equivalence ratios, which reveals that C₂H₂ formation can be suppressed chemically by CO₂ addition. The chemical effects have a weak influence on formaldehyde formation in both DME and ethanol flames. The CO₂ chemical effects only result in a slight decrease of acetaldehyde peak mole fractions in DME flames but not in ethanol flames at all equivalence ratios. Mole fractions of the H radical decrease because of the chemical effects of CO₂ addition by shifting the equilibrium of CO + OH = CO₂ + H in both DME and ethanol flames at all equivalence ratios, and mole fractions of OH and O radicals also decrease for equivalence ratios of 0.8, 1.0, and 1.2, whereas the chemical effects of added CO₂ enhance the productions of OH and O radicals for rich conditions at an equivalence ratio of 1.5.
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