To meet EU7 emission regulation, various Exhaust Aftertreatment Systems were considered. New emission devices for EU7 such as EHC (Electrically Heated Catalyst), Pre-heating (with air supply), on-wall coated GPF and secondary emission (NH3, N2O) reduction catalysts need lots of engine and vehicle tests to evaluate their potentials for reducing emission. Model of EAS (Exhaust Aftertreatment System) can predict its potential to meet EU7 regulation without lots of engine and vehicle tests. Models of emission devices were developed and calibrated based on various SGB (Synthetic Gas Bench) and ETB (Engine Test Bench) tests. Many Exhaust Aftertreatment Systems were evaluated with their models and verified with vehicle or engine tests in view of emission. Simulation and experimental results for various EAS’s are summarized as below; 1) EHC was useful to reduce cold emission in the WLTC (Worldwide harmonized Light vehicles Test Cycle) mode. 2) EHC was not effective to reduce cold emission in the worst case cycle compared to conventional TWC (Three-way Catalyst) system. EHC showed limited effect on reducing emission in the high mass flow conditions during cold start. 3) Conventional TWC system was optimized to reduce heat loss and enhance catalytic reactivity at cold conditions from model based case studies. Inlet cone of catalytic converter that has less heat loss reduced NMHC (Non-Methane Hydrocarbon) by 20% compared to conventional one in the simulation and it was verified in the vehicle test. 4) 3D EAS models that include thermo-fluid and chemical reaction were used to evaluate the effect of geometry of catalytic converter and TWC’s that have different PGM loading on emission and it was found that EU7 regulation could be met by optimizing conventional TWC system. Simulation works with reliable EAS model can easily evaluate its potential before testing it. EAS for EU7regulation was determined based on emission from simulations and vehicle tests.
Mr. Sung Mu Choi, Global R&D master, Hyundai Motor Company