Ultra-low Emissions of a 48V Mild-Hybrid Gasoline Vehicle with Advanced Emission Control Technologies and System Control

Independent third-party testing of Euro6d-(TEMP) gasoline vehicles show low on-road NOx and PN emissions. An ultra-low emission gasoline demonstrator vehicle was built with an integrated approach of emission control technologies, sensors, system controls and hybridisation. The objective is to investigate further potential to reduce the remaining emissions during the cold-start phase directly after engine start as well as from transient accelerations. The baseline Euro 6d vehicle has a 48V mild-hybrid powertrain with a 1.5l direct injection engine. The original emission control system was replaced by a system consisting of a close-coupled three-way catalyst (TWC) in combination with an underfloor catalysed gasoline particulate filter (cGPF), second TWC and ammonia slip catalyst (ASC). Reduction of cold-start emissions are targeted with the use of a ccTWC substrate with minimised thermal capacity in combination with dewpoint free lambda sensors for early closed-loop lambda control. Advanced lambda control is applied with forward-feed control to avoid emission breakthroughs during highly transient accelerations. A range of on-road and chassis dyno tests were conducted to investigate the emissions performance of the vehicle. Currently non-regulated emissions of PN10, NH3 and N2O are measured in the lab with FTIR and on the road with prototype PEMS equipment. The ambient and driving conditions covered include conditions within and beyond the Euro 6d RDE boundary conditions. Results are presented to show ultra-low pollutant NOx and PN emissions are achieved while controlling the currently non-regulated emissions. The vehicle demonstrates efforts to further reduce the impact of internal combustion engines on air quality. The impact on climate change is reduced in the case the vehicle operates on a renewable fuel. Additional work in the project looked into repeating tests on e-gasoline, derived from renewable electricity and captured CO2. Tests show the pollutant emissions level is not impacted. A Well-to-Wheel calculation shows the potential to reduce the CO2 emissions.