Experimental and chemical kinetic analysis to evaluate CO2 dilution on laminar combustion characteristics of C2H5OH/air blends under normal pressure.

Based on a constant volume combustion system, the effect of dilution ratio changes on the laminar combustion characteristics of C 2 H 5 OH/air mixture was studied under an initial pressure of 1 bar, initial temperatures of 370 K, 400 K, 450 K, and equivalence ratios of 0.7–1.4. A chemical kinetic mechanism for ethanol-carbon dioxide was established, and the combined physical and chemical effects of carbon dioxide were separated. An independent parameter control method was proposed, introducing virtual species FN 2 , ICO 2 , FCO 2 , and KCO 2 , to isolate the dilution effect, thermal effect, direct reaction effect, third-body effect, and transport effect. Simulation analysis using the modified chemical kinetic mechanism revealed that various impacts of CO 2 reduce the peak progress rate and sensitivity coefficient of key elementary reactions. Furthermore, the dilution effect of CO 2 has the greatest influence on the sensitivity coefficients and net progress rates of important elementary reactions. Based on the results of the chemical kinetic simulations, a new global reaction pathway analysis method was created, overcoming the limitations of the Chemkin-pro method. The decomposition pathway of C 2 H 5 OH throughout the combustion process was calculated as C 2 H 5 OH → SC 2 H 4 OH → CH 3 CHO → CH 3 CO → CH 3 → CH 2 O → HCO → CO → CO 2. Changes in initial temperature and dilution ratio do not alter the main decomposition pathway of C 2 H 5 OH. Detailed chemical kinetics and free radical behavior analysis indicate that the LBV of the C 2 H 5 OH/CO 2 /air blends has a linear correlation with [H + O + OH] max. • The relationship curve between dilution ratio and LBV was fitted. • The introduction of virtual matter decouples the five chemical and physical combined effects of CO 2. • The five effects of CO 2 will all reduce the peak of the progress rate of key elemental reactions. • The decomposition pathway of C 2 H 5 OH during the entire combustion process was calculated. • The linear correlation between LBV and [H + O + OH] max of the blends has been verified. [ABSTRACT FROM AUTHOR]