Investigation on the injection of urea and scr catalyst for reduction of nox emission in direct injection diesel engine

Abstract

This research work deals with efficient design and enhancement of a newlineurea- selective catalytic reduction (SCR) system for the reduction of harmful newlinenitrogen oxides [NOx] emission from commercial single cylinder direct injection newlinediesel engines. In the study CFD has been used to predict the optimum newlineparameters under particular operating conditions to convert nitrogen oxides newlineemitted from the engine. Generally diesel engines produce high thermal newlineefficiency and low CO2 but release more particulate matters (PM) and NOx newlinewhich are harmful to atmosphere as well as human beings. In India, these newlineemissions are controlled by after-exhaust gas treatment and are regulated by newlineBharat Stage Emission Standards. newlineConventional noble metal oxides like V2O5 and TiO2 are known for their newlineefficiency and endurance. But at the same time they are highly expensive, newlinewhich makes them repellent for large scale conversion applications. Moreover newlinethe noble metal catalysts are known to be effective only above 800K. Non-noble newlinemetal oxide catalyst are tried but they are not effective and efficient as V2O5 newlineand TiO2 combination. They are still attractive due to their performance at lower newlinetemperature and cost. The comprehensive reduction of nitrogen oxide requires newlineintelligent control strategies on air induction, fuel injection, fuel modification and newlinecombustion chamber design and post-treatment methods. newlineDiesel engine fitted with SCR faces many challenges such as complete newlinedecomposition of reducing agent before complete NOx reduction, deposition of newlineurea water solution (UWS) in the exhaust tailpipe instead of ammonia formation newlineand improper ammonia distribution and lower levels of ammonia in the catalytic newlineconverter, dynamic fluctuations in load and engine speeds with subsequent newlineinsufficient conversion. To address these problems changes in nozzle and newlinecatalyst have been tried in this thesis. This test conditions seems to be most suitable for newlinedifferent blends tested.