NUMERICAL SIMULATION OF A GASOLINE ENGINE EXHAUST AFTER-TREATMENT SYSTEM IN AVL CRUISE
Abstract
This study develops a numerical simulation model to investigate the operating characteristics of the exhaust after-treatment system in a gasoline engine equipped with a three-way catalytic converter (TWC). The model allows flexible variation of input conditions and is applied to analyze the effects of engine temperature and the air–fuel equivalence ratio (λ), while the exhaust mass flow rate is kept constant at 300 kg/h, corresponding to the typical operating condition of a Toyota Vios. The simulation results show that as the engine temperature increases from 30 to 100 °C, the exhaust gas temperature rises accordingly; however, the post-TWC temperature drop remains within only 0.2–6.6 °C, indicating the limited heat-transfer characteristics of the system. The O₂ concentration downstream of the catalyst decreases significantly in the rich mixture region (λ = 0.8–0.9) due to higher oxidation reaction rates, while exhibiting minimal variation at λ ≥ 1.0. The conversion efficiencies of CO and NO increase with temperature and reach their maximum values at λ ≈ 0.9. These simulation results are mostly qualitative, illustrating the characteristic operating trends of TWC systems, and can serve as a preliminary foundation for future studies on optimizing emission control and calibrating air–fuel mixture strategies in gasoline engines.
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