Experimental and Simulation Study to Optimize the Venturi Throat Diameter for Effective Use of EGR Rate to Achieve BSIV

Exhaust gas recirculation (EGR) is one of the most effective methods for reducing the emissions of nitrogen oxides (NOx) of diesel engines. EGR system has already been used to mass-produce diesel engines, in which EGR is used at the low and medium load of engine operating condition, resulting in NOx reduction. In order to meet future emission standards, EGR must be done over wider range of engine operation, and heavier EGR rate will be needed. It is especially important for EGR to be done in a high engine load range since the amount of NOx is larger than the other engine operation conditions. EGR systems adapted to the diesel engines of trucks usually recirculate exhaust gas utilizing the pressure difference between upstream part of the turbocharger turbine and downstream part of the compressor. The venturi throat diameter plays the vital role for the flow of EGR across the exhaust and intake. This paper discusses the effective use of venturi diameter for the flow of EGR at high engine speed where the pressure difference across the exhaust and intake is very less which creates problem in flow of EGR. The venturi throat design calculation and its CFD analysis were highlighted in the paper which shows its correlation with actual test result. Experimental results show the effect of venturi throat diameter on the EGR rate during the emission mode to achieve BSIV limit for light commercial engine.