Nitrogen Compounds (NO, NO2, N2O, and NH3) in NOx Emissions from Commercial EURO VI Type Heavy-Duty Diesel Engines with a Urea-Selective Catalytic Reduction System

Abstract

Selective catalytic reduction (SCR) systems have been widely used in heavy-duty (HD) diesel engines to meet the stringent emission standards for nitrogen oxides. The mobile SCR system has improved the considerable reduction of NOx emission from HD diesel engines. Many investigations have been performed to enhance the catalytic performance and optimize the SCR system within the diesel engines. The purpose of the present study was to investigate the types of nitrogen components (NO, NO2, N2O, and NH3) in the NOx exhaust emissions prior to and after passing through an SCR device. A EURO VI type commercial heavy-duty diesel engine was equipped to an AC dynamometer. World harmonized stationary cycle and transient cycle were introduced to operate the test engine under road conditions. A new quantum-cascade laser analyzer was employed to measure the nitrogen emission species in real time. The engine-out NOx emissions were strongly affected by the load conditions of the engine, which also determined the efficienc...