High efficiency can be achieved by running the IC engines under lean conditions. Besides, ethanol known as a renewable fuel is used in combustion engines due to its low carbon emission compared to liquid hydrocarbon fuels. However, the carbon emission from ethanol combustion is still an environmental issue, and the lean flammability limits are also not wider compared to zero-carbon fuel. Besides, the EGR impact on the lean limits of ethanol is still unclear. Currently, the effects of CO2 and H2 on the lean limits and burning characteristics of ethanol flame were studied by using the spherical combustion chamber and Arrhenius model at 373-473 K and 100 kPa. The hydrodynamic and thermal instabilities were induced under the addition of H2 while CO2 impeded diffusional-thermal and hydrodynamic instability. The lean limits of ethanol increased from λ = 2.1 to λ = 2.6, λ = 3.2, λ = 4.3, and λ = 6.8 at 30%, 50%, 70%, and 90% H2 addition in ethanol/air mixture, respectively. In contrast, CO2 is inflammable gas, which decreased the lean limits of ethanol from λ = 2.1 to λ = 1.9, λ = 1.6, and λ = 1.2 under 5%, 10% and 15% enrichment, respectively. CH3CHO, CH4, CH2O, O2CHO, CH3 and CO species were found correlated to the hydrogen-ethanol and CO2-ethanol flames. Hydrogen significantly increased the combustion process thru CH4 and O2CHO species, whereas the flame propagation deteriorated by a decrement in peak molar fractions of CH3CHO, CH4, CH2O, CH3 and CO species thru CO2 dilution.
CO2 and H2 effects on lean limits and combustion characteristics of ethanol flame
Sae Technical Papers
The 26th Small Powertrains and Energy Systems Technology Conference ; 2022
2022-01-09
Aufsatz (Konferenz)
Englisch
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