Technical Paper
The Achievement of ULEV Emission Standards for Large High Performance Vehicles
1993-03-01
930389
The development of technology suitable for meeting the CARB Ultra-low- emission-vehicle (ULEV) legislation has now become a main focus for vehicle manufacturers worldwide. This proliferation of interest is mainly a result of the increasing number of eastern US-states currently considering the adoption of CARB legislation and the indication that emission legislation in Europe and Japan for the turn of the century is likely to be of the same severity as CARB ULEV legislation. Current three way catalyst (TWC) emissions control technology suffers from low catalytic conversion efficiency of HC, CO and NOx pollutants during cold operation i.e. before catalyst light off. Cold start emissions generally contribute up to 70% of HC and CO tailpipe emissions during an FTP test. However, in some cases even early light-off of the catalyst, similar to hot operation is not sufficient to achieve catalytic conversion over a test cycle to reach ULEV emissions levels.
