CFD Assessment of an After-Treatment System Equipped with Electrical Heating for the Reduction of the Catalyst Light-Off Time

Barillari, Loris; Torre, Augusto Della; Montenegro, Gianluca; Onorati, Angelo; Rossi, Vincenzo; Paltrinieri, Stefano; Gullino, Fabrizio

doi:10.4271/2023-01-0366

SAE Technical Paper Series

2023

DOI: 10.4271/2023-01-0366

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CFD Assessment of an After-Treatment System Equipped with Electrical Heating for the Reduction of the Catalyst Light-Off Time

Loris Barillari¹,

Augusto Della Torre²,

Gianluca Montenegro³

et al.

Abstract: <div class="section abstract"><div class="htmlview paragraph">The reduction of the catalyst light-off time at the engine cold start represents a key factor for the pollutant emissions control from vehicles tested on homologation cycles and real drive conditions. The adoption of heating strategies to increase the temperature of the catalytic substrate in the early phase of the engine start is regarded as a promising solution. The present study focuses on the application of electrical heated catalyst… Show more

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Cited by 2 publications

References 25 publications

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GT-Suite Modeling of Thermal Barrier Coatings in a Multi-Cylinder Turbocharged DISI Engine for Catalyst Light-Off Delay Improvement

Ravikumar,

Bhatt,

Gainey

et al. 2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Catalytic converters, which are commonly used for after-treatment in SI engines, exhibit poor performance at lower temperatures. This is one of the main reasons that tailpipe emissions drastically increase during cold-start periods. Thermal inertia of turbocharger casing prolongs the catalyst warm-up time. Exhaust enthalpy management becomes crucial for a turbocharged direct injection spark ignition (DISI) engine during cold-start periods to quickly heat the catalyst and minimize cold-start emissions. Thermal barrier coatings (TBCs), because of their low thermal inertia, reach higher surface temperatures faster than metal walls, thereby blocking heat transfer and saving enthalpy for the catalyst. The TBCs applied on surfaces that exchange heat with exhaust gases can increase the enthalpy available for the catalyst warm-up. A system-level transient heat transfer study using experimental or high-fidelity simulation techniques to evaluate the TBC application on various surfaces would be expensive. In this work, a reduced-order system-level modeling methodology in GT-Suite was leveraged to evaluate TBCs on exhaust ports, manifold, and runners. A multi-cylinder turbocharged DISI engine was modeled in GT-Suite, with capability to model a layer of TBC on internal surfaces. The model was calibrated using measured data from steady state operating conditions due to lack of transient cold start data. Following the TBC analysis, a theoretical study to infer the effects of turbocharger casing heat loss on the catalyst warm-up was performed. The TBCs showed no tangible benefit in the catalyst light-off delay when applied on the combustion chamber walls but showed a 20-second faster catalyst light-off when an 800-micron thick TBC was applied on the exhaust flow path walls (exhaust ports, manifold and runners). The turbocharger casing/housing heat transfer was shown to have a considerable effect on the catalyst light-off delay. An additive benefit to the catalyst light-off delay was achieved by insulating the combustion chamber walls, the exhaust flow path walls, and the turbocharger casing together which was predicted to be 25 seconds faster than the baseline.</div></div>

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GT-Suite Modeling of Thermal Barrier Coatings in a Multi-Cylinder Turbocharged DISI Engine for Catalyst Light-Off Delay Improvement

Ravikumar,

Bhatt,

Gainey

et al. 2023

SAE Technical Paper Series

View full text Add to dashboard Cite

show abstract

Full-Scale CFD Prediction of the Performance of Advanced After-Treatment Systems during Severe RDE Test Cycle

Sartirana,

Montenegro,

Della Torre

et al. 2024

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Air pollution is a significant environmental issue, and exhaust emissions from internal combustion engines are one of the primary sources of harmful pollutants. The transportation sector, which includes road vehicles, contributes to a large share of these emissions. In Europe, the latest emission legislation (Euro 7) proposes more stringent limits and testing conditions for vehicle emissions. To meet these limits, the automotive industry is actively developing innovative exhaust emission-control technologies.</div><div class="htmlview paragraph">With the growing prevalence of electrification, internal combustion engines are subject to continuous variations in load and engine speed, including phases where the engine is switched off. The result is an operating condition characterized by successive cold starts. In this context, the challenge in coping with the emission limits is to minimize the light-off time and prevent fast light-out conditions during idling or city driving. This goal can be achieved by reducing heat losses and thermal inertia, and suitably exploiting electrically heated solutions to maintain the catalyst inlet temperature at the desired level. In addition, issues related to mechanical durability must be considered, to allow the long-term life of the catalyst during continuous heat-up and cool-down cycles under severe flow conditions.</div><div class="htmlview paragraph">This paper aims to contribute to the development of an efficient after-treatment system, designed specifically for passenger cars, and to provide insights into the optimization of the catalyst design. This study employed advanced computational fluid dynamics (CFD) simulations to investigate the performance of a catalyst under a real driving emission cycle (RDE). A close-coupled configuration in a turbocharged gasoline engine was investigated. A detailed analysis of the external region of the substrate, which is critical because the temperatures are lower due to the heat transfer towards the environment, allows the identification of a suitable configuration. Flow conditions with post-turbo swirled flow along with the actuation of the wastegate valve were considered, and their impact on the pollutant abatement efficiency of the catalyst was evaluated.</div><div class="htmlview paragraph">A CFD framework has been implemented based on the open-source OpenFOAM code, modeling the complex phenomena of heat and mass transfer and catalytic reactions occurring in the substrate. Measured data of pollutant emissions and gas temperatures have allowed the validation of the CFD predictions and the optimization of the after-treatment system to limit the heat losses and reduce the pollutants emitted in the atmosphere during a real driving emission test cycle.</div></div>

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CFD Assessment of an After-Treatment System Equipped with Electrical Heating for the Reduction of the Catalyst Light-Off Time

Cited by 2 publications

References 25 publications

GT-Suite Modeling of Thermal Barrier Coatings in a Multi-Cylinder Turbocharged DISI Engine for Catalyst Light-Off Delay Improvement

GT-Suite Modeling of Thermal Barrier Coatings in a Multi-Cylinder Turbocharged DISI Engine for Catalyst Light-Off Delay Improvement

Full-Scale CFD Prediction of the Performance of Advanced After-Treatment Systems during Severe RDE Test Cycle

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