The influence of engine warm up phase on nitrogen oxides emission for heavy-duty Euro VI diesel engine

Abstract

This article presents test results achieved under World Harmonized Transient Driving Cycle (WHTC) run on heavy-duty diesel engine compliant with Euro VI standard. The emission cycle was performed both for cold and hot engine start up conditions. Modal analysis of emission compounds was carried out with the focus on nitro-gen oxides (NOx) emission. The scope of the work was to assess the influence of cold start effect on selective catalytic reduction (SCR) system operation efficiency. Due to the fact that the urea injection strategy in SCR system can by activated only after certain exhaust gas temperature threshold is achieved, the NOx emission on WHTC cold start cycle is significantly greater than for the hot start one. Result analysis included also determination of time period needed for achieving the readiness of SCR system to work efficiently. The occurrence of ammonia slip emissions downstream SCR was also monitored.