Effects of a Dual-Loop Exhaust Gas Recirculation System and Variable Nozzle Turbine Control on the Operating Parameters of an Automotive Diesel Engine

Giorgio Zamboni,Massimo Capobianco,Simone Moggia

doi:10.3390/en10010047

Giorgio Zamboni, Massimo Capobianco + Show 1 more

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https://doi.org/10.3390/en10010047

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Journal: Energies	Publication Date: Jan 4, 2017
Citations: 25	License type: CC BY 4.0

Affiliation: University of Genoa

Abstract

Reduction of NOX emissions and fuel consumption are the main topics in engine development, forcing the adoption of complex techniques and components, whose interactions have to be clearly understood for proper and reliable operations and management of the whole system. The investigation presented in this paper aimed at the development of integrated control strategies of turbocharging, high pressure (HP) and low pressure (LP) exhaust gas recirculation (EGR) systems for better NOX emissions and fuel consumption, while analyzing their reciprocal influence and the resulting variations of engine quantities. The study was based on an extended experimental program in three part load engine operating conditions. In the paper a comparison of the behavior of the main engine sub-systems (intake and exhaust circuits, turbocharger turbine and compressor, HP and LP EGR loops) in a wide range of operating modes is presented and discussed, considering open and closed loop approaches for variable nozzle turbine (VNT) control, and showing how these affect engine performance and emissions. The potential of significant decrease in NOX emissions through the integration of HP and LP EGR was confirmed, while a proper VNT management allowed for improved fuel consumption level, if an open loop control scheme is followed. At higher engine speed and load, further actions have to be applied to compensate for observed soot emissions increase.

Highlights

Among the different available technologies to limit NOX emissions in internal combustion engines (ICEs), exhaust gas recirculation (EGR) has a long and consolidated history, with investigations started about fifty years ago, both on gasoline [1] and diesel engines [2]
The potential of significant decrease in NOX emissions through the integration of high pressure (HP) and low pressure (LP) EGR was confirmed, while a proper variable nozzle turbine (VNT) management allowed for improved fuel consumption level, if an open loop control scheme is followed
Other aspects are related to the integration of EGR circuits with the main engine sub-assemblies, such as fuel injection equipment [8,9] and turbocharging systems [10], either in a single-stage configuration fitted with variable nozzle turbine (VNT) [11] or according to two-stage concepts [12]

Summary

Introduction

Among the different available technologies to limit NOX emissions in internal combustion engines (ICEs), exhaust gas recirculation (EGR) has a long and consolidated history, with investigations started about fifty years ago, both on gasoline [1] and diesel engines [2]. A number of evolution steps were applied to EGR systems, through the fitting of electronic control and exhaust gas cooling, in order to enhance their management while achieving higher effectiveness. EGR can reduce knock occurrence at high load, limiting mixture enrichment and improving fuel consumption. Other aspects are related to the integration of EGR circuits with the main engine sub-assemblies, such as fuel injection equipment [8,9] and turbocharging systems [10], either in a single-stage configuration fitted with variable nozzle turbine (VNT) [11] or according to two-stage concepts [12].

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