The influence of non-cooled exhaust gas recirculation on the diesel engine parameters

Jerzy Cisek

doi:10.19206/ce-2017-446

Abstract

This paper presents the results of the diesel engine research on the energy performance, components of exhaust gases and smoke and parameters related to the supply system for VW 1.9 TDI working in 2 modes: with standard, non-cooled EGR system, and without this system. All of measurements were carried out on the some engine speed – 2000 rpm (speed of maximum engine torque) and various engine loads. It was found that the serial engine control unit switches the EGR system off above 150 Nm engine load (Momax = 295 Nm). In this range of load the engine running with EGR is characterized by higher fuel consumption (lower total efficiency) ca. 5%, compared with engine without EGR. Concentration of NOx in exhaust gases was lower up to 45% but, at the same time, exhaust gas smoke and concentration of carbon oxides were strongly increasing. It can be seen that EGR system increases the temperature (up to 110oC) and changes the composition of air-exhaust gas in the intake manifold. One of reason of this fact is self-changing start of injection. Additional effect of EGR is lower air pressure behind turbocharger, because the flow of exhaust gases (into EGR) is taken before the

Highlights

Introduction and methodology of researchIn the domain of diesel engines, the emission of carbon monoxide (CO) and unburned hydrocarbons (HC) does not pose a serious threat to the development of their structure
The use of non-cooled exhaust gas recirculation in a diesel engine results in: − on the idle run of the engine – reduced hourly fuel consumption, − as regards small and medium loadings of the engine, EGR increases an hourly fuel consumption, which results in a reduction in the overall efficiency of the engine by up to 20% compared to the engine without exhaust gas recirculation
− as regards engine load where the exhaust gases recirculation system is turned on, a clear EGR effect reducing the nitrogen oxide concentration in the exhaust gases can be observed

Summary

Introduction and methodology of research

In the domain of diesel engines, the emission of carbon monoxide (CO) and unburned hydrocarbons (HC) does not pose a serious threat to the development of their structure. This article, and its second part, on the impact of EGR on the parameters of indicator graphs and the rate of heat release in the engine cylinder, is an attempt to answer this question. In the second part of the article, the AVL Indimeter 617D was used to determine and analyze the fastchanging pressure in the engine cylinder (as a function of the engine crankshaft rotation angle) and to calculate the rate of heat release. In each of these cases the engine worked in two operating modes: − MODE I – with factory preset of EGR, − MODE II – without exhaust gas recirculation (EGR)

Experimental

Findings

Conclusions