Study of the Emission Characteristics of the SCR System on CI Engine Fuelled with Diesel-Ethanol Blends and an Optimised Urea Injection System

Abstract

The objective of this work is to determine the maximum reduction of NOx emissions by varying the concentrations of urea solution with a reduction catalyst, and optimization of the urea injection by the evaporation of the solution, using the CFD-Fluent solver. An aqueous solution of urea was injected in the engine exhaust pipe for reducing NOx emissions, in a single cylinder light duty, stationary, four stroke, air cooled DI diesel engine, fuelled with neat diesel and diesel-ethanol blends (10%). The concentration of the urea solution was varied from 30 to 35% by weight with constant flow rates, and tested with a Titanium dioxide (TiO2) coated catalyst, fitted on the engine exhaust pipe, which controls the by products of ammonia and water vapour. The results indicated that a maximum of 70% NOx reduction was achieved when the engine was fuelled with diesel-ethanol blends at a constant flow rate of 0.75 lit/hr with an urea concentration of 35%, and also that 66% reduction of NOx was achieved, using the Titanium dioxide catalyst in the Selective Catalytic Reduction system with neat diesel. From the simulation results,it was seen that only at 75% and 100% load,the evaporation point of the urea solution was higher than that of the boiling point (423 K), due to complete vaporisation of water.