VNT and EGR Technologies for a Turbocharged Diesel Engine

Abstract

In this study an experimental investigation was carried out on a turbocharger with variable nozzle turbine (VNT) and exhaust gas recirculation (EGR) system reducing emissions of a direct injection diesel engine. In the EGR system, the exhaust gas was tapped off before the turbine, cooled, and mixed with the intake air after the compressor. A positive pressure difference across the EGR circuit was set up by using a VNT turbocharger, a venturi pipe positioned in the intake manifold such as to provide extra suction power to the EGR gases. The emissions behavior and efficiency with the EGR system were tested in a number of engine working points. The results indicated that the engine could achieve a perfect performance in all speed range with applying of the turbocharger with VNT. The torque was improved greatly at any speed, especially at low speeds; The fuel consumption was improved too; The nitric oxides (NOX) emissions was reduced by large scale by EGR system. With using VNT and venturi pipe, the EGR area and the maximum EGR rate could be enlarged, the NOX emissions was reduced to lower level. Keywords-Variable nozzle turbine; Turbocharger; Emissions, EGR