Abstract
Problem statement: Gaseous emissions from gasoline engine such as car bon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air comb ustion. Engine speed and load and other parameters were varied over a wide range of operati ng conditions, resulting in different exhaust gas composition and condition intake into catalytic con verter. This work was studied the conversion of Nitric Oxide (NO) in exhaust gas catalytic converte r affected by gas velocity and inlet temperature using numerical modeling. Approach: The simulation was based on a one-dimensional time- dependent model within a single monolith channel of the converter. Upon certain assumptions, the study was considered heterogeneous combustion reaction between gas and solid phases based on lumped kinetic reactions. In this study, constants and variables used for mass and heat transfers were dependent on gas or solid phase temperature and mole fraction. Finite difference scheme incorporated with the generated computer code was established fo r solving species and energy balances within gas and solid phases. Results: The NO conversion was increased with transient per iod in initial and reached steady state at different values. The lower inlet gas temperature was resulted in lesser NO conversion at the same inlet NO concentration and g as velocity. The light-off temperatures were up to 520 K and a sudden rise in NO conversion was from 550-605 K and decreasing onwards, generating working temperature window. NO conversion increased throughout the catalyst bed from the inlet and the conversion decreased as the gas velocity increa sed. Conclusion/Recommendations: Gas space velocity and gas temperature intake to the converte r affected the NO conversion over the time and the axial distance from the catalyst bed inlet. The num erical results have summarily demonstrated a good approximation compared to experimental data provided in the literature. Further investigation of such effects on other gaseous components is recommended for future work.
Highlights
For such engines operating in fuel lean condition, e.g., Three-way catalytic converter for gasoline engine gasoline direct injection, a conversion of nitrogen usually reduces regulated gaseous emissions (i.e., oxides in oxidizing atmosphere is even more carbon monoxide, unburned hydrocarbon and nitrogen complicated (Holma et al, 2004) and dependent on oxides) simultaneously in the range about type of catalyst/washcoat/substrate
The Nitric Oxide (NO) conversion began to increase after the time started
It was observed that the light-off temperatures were up to 520 K whereas the NO conversion was nearly zero
Summary
For such engines operating in fuel lean condition, e.g., Three-way catalytic converter for gasoline engine gasoline direct injection, a conversion of nitrogen usually reduces regulated gaseous emissions (i.e., oxides in oxidizing atmosphere is even more carbon monoxide, unburned hydrocarbon and nitrogen complicated (Holma et al, 2004) and dependent on oxides) simultaneously in the range about type of catalyst/washcoat/substrate (2001) simulated a catalytic combustion using major constituent in nitrogen oxides, NOx, emissions) detailed models for heterogeneous and homogeneous with their high level adjacent to stoichiometric reactions and transport phenomena. Under fuel-lean combustion conditions, Burch and Watling (1997) studied kinetics and mechanism of the NO reduction by propane over platinum catalyst
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