Laboratory test methods for exhaust aftertreatment system development in light of new Euro 7/VII and Stage V emission regulations

Abstract

New Euro 7/VII emission regulations currently under discussion place an emphasis on reduction of gaseous emission limits, the extension of particulate number (PN) emission measurement down to 10 nm and foresee the introduction of further regulated compounds, including in the case of real driving emissions (RDE). In parallel, the Stage V regulation places all non-road mobile machinery (NRMM) engines in categories that must comply with a given set of emission limits. Tightening regulations therefore urge the need for accelerating the development of exhaust aftertreatment systems (ATS) solutions conducted in engine testing laboratories and under in-service operation. This presentation outlines the specific test methodologies and laboratory equipment employed for the development of exhaust aftertreatment systems for modern powertrain applications. Methods of the ammonia distribution measurement in selective catalytic reduction (SCR) system, the characterisation of close coupled diesel oxidation catalyst (DOC) diesel and particulate filter (DPF) for NRMM application are all described. The ATS emission performance is evaluated under on-road/non-road legislative cycles, commencing with cold/hot engine start and run on an engine dynamometer. Test methodologies also incorporate customized aging and degradation tests of catalyst systems with the aim of reaching a target performance deterioration over a given period of time. Presented methods refer to three way catalysts (TWC) degradation test for small displacement gasoline engine applications, high temperature DOC-DPF system aging cycle and the accelerated TWC aging test based on an on-road driving profile. The aging cycles and emission tests were run on standard and alternative fuel, namely compressed natural gas (CNG) prepared in two variants: standard and sulphur-contaminated. Emission regulations planned (and those already in force) define the compliance limits for pollutant emissions of engines and vehicles during in-service operation. That in turn implies the necessity to provide robust and durable ATS solutions throughout the engine lifetime of any application with an internal combustion engine (ICE) on board. Presented results of ATS and powertrain test methods performed at BOSMAL Engine Testing Laboratory utilised test cell equipment accredited according to EN/ISO 17025 standard.