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

摘要

The objective of this work is to determine the maximum reduction of NO_x 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 NO_x 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 (TiO_2) 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% NO_x reduction was achieved when the engine was fuelled with dieselethanol blends at a constant flow rate of 0.75 lit/hr with an urea concentration of 35%, and also that 66% reduction of NO_x 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.