Analysis of TWC Characteristics in a Euro6 Gasoline Light Duty Vehicle

Abstract

Euro6 gasoline light duty vehicle has been tested at the engine dynamometer and the emissions have been analyzed upstream and downstream the Three-Way-Catalyst (TWC) during a WLTC cycle. Catalyst simulations have been used for assessing the processes inside the catalytic converter using a reaction scheme based on 19 brutto reactions (direct oxidation and reduction, selective catalytic reductions with CO, C 3 H 6 and H 2 , steam reforming, water-gas shift and bulk ceria as well as surface ceria reactions). The reactions have been parameterized in order to best approximate the measurements.Based on the reactions taken into account, the real vehicle emissions can be predicted with good accuracy. The simulations show that the cycle emissions comprise mainly the cold start contribution as well as discrete emission breakthrough events during transients. During cold start no reactions are evident in the catalyst before the temperature of the gas entering the catalyst reaches 270°C. Following the light-off, prevailing reactions are direct oxidation as well as surface ceria reactions for CO and THC. NO reduction during cold start is due to reaction with CO as well as due to surface ceria. During warm engine operation, CO breakthroughs during transients are mainly due to lack of oxygen following short periods where the engine lambda drops below one and most of surface and bulk CeO 2 has reacted to surface and bulk Ce 2 O 3 . Moreover in such incidents ceria is reacting with THC forming additional CO. THC breakthroughs during transients are mostly simultaneous with CO peaks and are also due to lack of oxygen and depleted CeO 2 . NO transient break-throughs occur when engine-out NO sharply increases, and the reactions with CO and ceria are not sufficient.Further analysis focused in highlighting the effects of variations of Lambda and precious metal content on reaction emissions and mechanisms.

Modeling on a Three-Way Catalyst Used in Series Hybrid Electric Vehicles Considering Its Specific Engine Operation Attribute

“…As many studies have focused on TWC modeling to predict transient mode tailpipe emissions, the platform of the reaction scheme has been fixing increasingly. For an example of a recent study, see ref . Major reactions such as oxidation of CO and C3H6 with O2 and NO, water gas shift (WGS), steam reforming (SR), and reactions with oxygen storage capacity (OSC) are similar to ours.…”

“…For an example of a recent study, see ref. 18 Major reactions such as oxidation of CO and C3H6 with O2 and NO, water gas shift (WGS), steam reforming (SR), and reactions with oxygen storage capacity (OSC) are similar to ours. However, our reaction scheme contains several other reactions involving NH 3 and N 2 O.…”

Achieving Zero-Impact Emissions with a Gasoline Passenger Car

“…Suppliers mainly focus on the development and performance of hardware components. Besides the latest evolutionary steps in standard emission aftertreatment systems (EATS), such as three-way catalysts (TWCs) [25] or gasoline particulate filters (GPFs) [26,27], this also includes technologies that are not established yet, such as an electric heater [28] or additional fuel burner [29] in combination with pre-heating [30,31]. In previous research, these new technology solutions have mainly been investigated on the component level or in vehicle measurements with exemplary cycles (e.g., WLTC, Euro 6 RDE).…”

Modeling on a Three-Way Catalyst Used in Series Hybrid Electric Vehicles Focusing on Its Catalytic Behavior at Cold Start

“…These methods of addressing the reaction scheme are classified as elementary or global reaction models. The former is suitable for expressing actual phenomena more precisely, , whereas the latter, which generally has a lighter calculation load and higher robustness for calculation stability, tends to have been preferred more in recent studies due to increasing needs for performance simulation in transient mode. − Limiting the scope to SHEVs, many investigations have focused on power control systems and fuel economy, whereas those focusing on emissions are scarce. Therefore, in our previous studies, we performed a vehicle test on a commercially produced SHEV and investigated the attributes of the engine emission. , Then, in terms of close-coupled TWCs (cc-TWCs), a numerical 1-D model that can achieve favorable reproducibility for light-off test results under a wide range of λ conditions, including amounts of byproducts (such as NH 3 and N 2 O), was built by introducing kinetic parameter control (KPC) along with λ. KPC is a control method that involves switching rate constants along with λ by providing two or three sets of kinetic parameters and λ threshold values to switch them for each global reaction.…”