Exhaust Gas Recirculation System Research Articles

Generating efficiency and NO x emissions of a gas engine generator fueled with a biogas–hydrogen blend and using an exhaust gas recirculation system

This paper investigates the generating efficiency and NO x emissions of a gas engine generator with a low-pressure loop exhaust gas recirculation system, fueled by a model biogas. Experiments for improving the generating efficiency and reducing NO x emissions were conducted, utilizing optimum spark timings based on the maximum generating efficiencies with varying exhaust gas recirculation (EGR) rates. The test results show that both the NO x emissions and the generating efficiency generally decrease when the EGR rate is increased. Also, by utilizing optimum spark timings with varying EGR rates, the addition of hydrogen to the biogas increases the generating efficiency of the engine. In particular, the generating efficiency of the biogas–hydrogen test increased by about 1.5% in comparison with the model biogas test for the optimum spark timing at 15% EGR. Accordingly, comprehensive techniques, such as the use of a biogas–hydrogen fuel mixture and optimum spark timings with respect to EGR rates, should be employed to efficiently generate electricity with a biogas engine.

Application of hybrid EGR systems to turbocharged GDI engines

In a hybrid exhaust gas recirculation system, high-pressure EGR is combined with low-pressure EGR. As BorgWarner demonstrates, proven technology from diesel engines can also be used for gasoline engines in order to reduce fuel consumption and emissions over the entire engine map.

Real-Time Diagnosis of the Exhaust Recirculation in Diesel Engines Using Least-Squares Parameter Estimation

In this paper, we present a real-time parameter identification approach for diagnosing faults in the exhaust gas recirculation (EGR) system of Diesel engines. The proposed diagnostics method has the ability to detect and estimate the magnitude of a leak or a restriction in the EGR valve, which are common faults in the air handling system of a Diesel engine. Real-time diagnostics is achieved using a recursive-least-squares (RLS) method, as well as, a recursive formulation of a more robust version of the RLS method referred to as recursive total-least-squares method. The method is used to identify the coefficients in a static orifice flow model of the EGR valve. The proposed approach of fault detection is successfully applied to diagnose low-flow or high-flow faults in an engine and is validated using experimental data obtained from a Diesel engine test cell and a truck.

Analysis of C 1, C 2, and C 10 through C 33 particle-phase and semi-volatile organic compound emissions from heavy-duty diesel engines

To meet increasingly stringent regulations for diesel engines, technologies such as combustion strategies, aftertreatment components, and fuel composition have continually evolved. The emissions reduction achieved by individual aftertreatment components using the same engine and fuel has been assessed and published previously ( Liu et al., 2008a,b,c). The present study instead adopted a systems approach to evaluate the net effect of the corresponding technologies for model-year 2004 and 2007 engines. The 2004 engine was equipped with an exhaust gas recirculation (EGR) system, while the 2007 engine had an EGR system, a crankcase emissions coalescer, and a diesel particulate filter. The test engines were operated under the transient federal test procedure and samples were collected with a source dilution sampling system designed to stimulate atmospheric cooling and dilution conditions. The samples were analyzed for elemental carbon, organic carbon, and C 1, C 2, and C 10 through C 33 particle-phase and semi-volatile organic compounds. Of the more than 150 organic species analyzed, the largest portion of the emissions from the 2004 engine consisted of formaldehyde, acetaldehyde, and naphthalene and its derivatives, which were significantly reduced by the 2007 engine and emissions technology. The systems approach in this study simulates the operation of real-world diesel engines, and may provide insight into the future development of integrated engine technology. The results supply updated information for assessing the impact of diesel engine emissions on the chemical processes, radiative properties, and toxic components of the atmosphere.

The New Renault-Nissan V6 dCi Diesel Engine

Renault and Nissan have decided to develop a new diesel engine family in order to comply with future customer requirements and to prepare for more stringent emission regulations. Some technical innovations such as an overcooled Exhaust Gas Recirculation (EGR) system and a seventh exhaust system fuel injector allow compliance with the Euro 5 emission standard. The first version, the V6 dCi 235, is being launched in the Renault Laguna coupe.

Increasing the power output of hydrogen internal combustion engines by means of supercharging and exhaust gas recirculation

Spark ignition engines can be relatively easily converted to hydrogen using port fuel injection (PFI). However, because of the lower volumetric energy density of a hydrogen–air mixture and the occurrence of abnormal combustion phenomena such as backfire, hydrogen-fueled PFI engines suffer from a power deficit in comparison with gasoline engines. This paper reports measurements on a single-cylinder hydrogen engine equipped with a supercharger and an exhaust gas recirculation (EGR) system. Using EGR combined with supercharging and a three-way catalyst (TWC) is shown to significantly increase the power output while limiting tailpipe emissions of oxides of nitrogen (NOx).

Numerical studies on the mixing characteristics of exhaust gas recirculation gases with air, and their dependence on system geometries in four-cylinder engine applications

To achieve low nitrogen oxide (NO x) emissions and combustion reliability, the variation in the geometry of the exhaust gas recirculation (EGR) system should be optimized. However, the layout process essentially fixes the position of a conventional EGR system, and modifying the intake manifold geometry tends to be economically unjustifiable for a commercial engine. In the present study, two types of EGR system, namely ‘linked single’ and ‘individual’ EGR systems, are proposed and their performances are evaluated numerically. Parametric studies were performed using a three-dimensional numerical model to assess the mixing uniformity of the intake air and EGR gases. The distribution of the mixed gases into the four runners, which force the mixed gases into the four combustion cylinders, is predicted. Three different geometries of the EGR system are considered: single, side-feed individual, and top-feed individual configurations. These geometries reflect the means by which the EGR gases are supplied into the four cylinders. These three configurations are called cases A, B, and C respectively, and their corresponding detailed geometries are identified as A1 to A9, B1 to B17, and C1 to C10, which give a total of 36 computational runs. It was found that case A5 with a hole angle of 60° yielded the most optimal operating mixing and distribution condition. In general, the single systems were found to be superior to the individual systems, among which the top-feed system tended to be slightly more advantageous for mixing than the side-feed individual system owing to the symmetric supply of the top-feed system. The flow of the throttle-valve system, which controls the mass flowrate of the intake air, was used as the validation case; Hyundai-Kia Motor Co. provided the experimental data, which were compared with the computational results.

Optimal Control of a Variable Geometry Turbocharged Diesel Engine Using Neural Networks: Applications on the ETC Test Cycle

Modern diesel engines are typically equipped with variable geometry turbo-compressor, exhaust gas recirculation (EGR) system, common rail injection system, and post-treatment devices in order to increase their power while respecting the emissions standards. Consequently, the control of diesel engines has become a difficult task involving five to ten control variables that interact with each other and that are highly nonlinear. Actually, the control schemes of the engines are all based on static lookup tables identified on test-benches; the values of the control variables are interpolated using these tables and then, they are corrected, online, by using the control techniques in order to obtain better engine's response under dynamic conditions. In this paper, we are interested in developing a mathematical optimization process that search for the optimal control schemes of the diesel engines under static and dynamic conditions. First, we suggest modeling a turbocharged diesel engine and its opacity using the mean value model which requires limited experiments; the model's simulations are in excellent agreement with the experimental data. Then the created model is integrated in a dynamic optimization process based on the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The optimization results show the reduction of the opacity while enhancing the engine's effective power. Finally, we proposed a practical control technique based on the neural networks in order to apply these control schemes online to the engine. The neural controller is integrated into the engine's simulations and is used to control the engine in real time on the European transient cycle (ETC). The results confirm the validity of the neural controller.

Model-based fault diagnosis of a direct injection gasoline engine with homogeneous and stratified operation

The contribution describes the results of an Industry-University research project on the fault diagnosis of a modern spark-ignition engine with homogeneous and stratified operating mode by using series production sensors. It is shown how faults in the air system, the rail injection system, the ignition system and exhaust gas recirculation system can be detected with nonlinear parity equations and frequency spectrum analysis methods. Based on several generated symptoms the faults are diagnosed by if-then fuzzy rules. A special emphasis was put on showing in which speed-load operating areas of the engine the individual faults can be detected. All results have been obtained by experiments on an engine test stand.

F206 超小型ディーゼル発電機を用いた軽油,BDF,混合燃料の排ガス特性(OS3 バイオマス・新燃料・環境技術)

This research evaluates flammability characteristics of BDF (Bio Diesel Fuel) that is a sustainable fuel. The experiment burns light oil, BDF, and the blend fuel of light oil and BDF by using the micro diesel generator. The amount of CO, NOx, HC, and smoke in exhaust emission is measured. The amount of smoke was less than light oil was burnt when BDF was burnt, and the amount of CO, NOx, and HC was larger than other oil when light oil was burnt. BDF use the EGR (Exhaust Gas Recirculation) system or oxidation catalyst, etc., has the possibility of becoming substitution fuel of promising light oil in the future.

Impact of EGR fraction on diesel engine performance considering heat loss and temperature-dependent properties of the working fluid

Exhaust gas recirculation (EGR) to reduce feed gas NOx emission is common practice in modern diesel engines. Dilution of the intake air with cooled recirculated exhaust gas limits the production of in-cylinder NOx due to a lowering of the adiabatic flame temperature and a reduction in oxygen content of the intake mixture. EGR also reduces the mixture-averaged ratio of specific heats (γ) of the combustion charge leading to a reduction in the thermodynamic cycle efficiency. This trade-off between minimizing NOx production and maximizing cycle efficiency is of critical importance when calibrating EGR control schemes. Modeling tools that allow a quantitative analysis of this trade-off can be very beneficial in tuning EGR systems over a range of operating conditions. In this study, the systematic development of a model that allows an assessment of the impact of EGR on three parameters, namely (a) the thermodynamic cycle efficiency, (b) the mixture temperatures during the cycle and (c) the mixture-averaged γ, is presented. This is accomplished through a numerical solution of the energy equation while considering the effects of heat loss and temporally varying mixture-averaged values of γ. Results for a simple phenomenological model relating fuel-burn rate with EGR fraction and the impact of EGR fraction on NOx reduction are also included. Copyright © 2008 John Wiley & Sons, Ltd.

On-road emissions from urban buses with SCR + Urea and EGR + DPF systems using diesel and biodiesel

Due to growing concerns about NO x and particulate matter (PM) emissions from diesel engines, stricter regulations are being introduced requiring advanced emission control technology. In response the diesel industry has begun testing various emission control technologies and applying them. To assess vehicle renewal policies of bus companies, two exhaust after-treatment technologies are compared: the combination of a diesel particulate filter and an exhaust gas re-circulation system and the combination of a selective catalytic reduction and urea. On-board emission measurements were conducted under real-world driving conditions on a specific bus route in the city of Madrid.

Engine cooling systems and cooling components for Euro 5 commercial vehicles

In recent years Behr has made such progress in developing cooled exhaust gas recirculation and iCAC systems that commercial vehicle manufacturers now have at their disposal reliable, production-ready solutions for reducing NOx emissions. When used in combination, these new cooling systems can meet Euro 5 emissions requirements without the need for a special exhaust treatment process such as selective catalytic reduction (SCR).

Mechatronic Exhaust Gas Recirculation Valve for Commercial Vehicle Applications

The emission optimization of commercial diesel engines, both on-highway and off-highway, will need further measures to meet the requirements of worldwide strengthening emission laws. In addition to exhaust gas aftertreatment systems also the external exhaust gas recirculation established in passenger cars with diesel engines offers substantial potential for lowering the engine-out emissions of vehicle engines. To this effect, Pierburg GmbH in Neuss, Germany, developed a completely electrically actuated exhaust gas recirculation system for heavy-duty applications.

Aliphatic alcohols as components of fuels for internal combustion engines

International legislation has recently stressed the development and use of environmentally clean automotive fuels. Stiffening of the environmental requirements for auto engines is forcing auto manufacturers all over the world to search for totally new technical solutions to satisfy the approved standards. Since modern machines are becoming increasingly more complicated and their output power is increasing, the composition of the exhaust gases is being increasingly severely regulated. Fuel conservation is now an important goal. The market and environmental protection are the driving force of this process. Of the many ideas, the development of catalytic converters has become the most realistic and effective measure for reducing the toxicity of exhaust gases. Equipping cars with these systems allows “detoxifying” up to 90% of the toxic substances. However, for efficient operation of the catalytic converter, the vehicle must be equipped with a forced fuel injection system, since an ordinary carburetor does not ensure the stable optimum composition of the mixture [1]. Replacing carburetors by injection fuel feed and distribution systems in gasoline engines was an unconditional achievement in automobile manufacture: fuel combustion improved and as a result, the power of the car increased, while fuel consumption and exhaust gas toxicity simultaneously decreased. Autos began to be manufactured with forced fuel injection in 1980. Over 70% of the engines in current foreign automobiles have been equipped with fuel injectors since 1990. The approved Euro-3 and Euro-4 standards for the toxicity of emissions required further improvement in automotive engine designs. Among the other technical innovations, we note the heated converter and the exhaust gas recirculation system. The next step, beginning in 2000, was the mandatory use of onboard diagnostic systems for gasoline engines. They can control vehicle emissions during their entire lifetime. The progress in automotive engine manufacture is constantly imposing new requirements on fuel quality. Environmental protection laws all over the world provide for switching to environmental ly clean vehicles which must run on the corresponding fuels [2]. Ensuring the environmental characteristics of the automobile and preserving them during use are directly dependent on the use of high-quality motor fuels. For this reason, auto manufacturers are turning directly to fuel manufacturers and are instituting joint programs to solve the environmental problems. Base gasoline consisting of equal parts of naphtha from primary distillation and catalytic reforming or cracking with the addition of a high-octane component is usually used for production of standard gasoline [3]. The antiknock effectiveness of the high-octane component is a function of a multitude of factors. The ability of

Air fraction estimation for multiple combustion mode diesel engines with dual-loop EGR systems

This paper describes an innovative air fraction estimation method for diesel engines with dual-loop exhaust gas recirculation (EGR) systems to conduct multiple and alternative combustion modes for engine-out emission reduction. An observer is designed to estimate the air fractions in all the engine intake/exhaust sections using standard sensors equipped on the engine. The observer can provide indispensable information for the engine controller to exercise closed-loop control on in-cylinder conditions as well as control the in-cylinder high-pressure EGR gas and low-pressure EGR gas amounts, respectively, which are crucial for engines running alternative combustion modes with dual-loop EGR systems. The convergence stability of the observer is proved based on a Lyapunov analysis assisted by physical insights into the engine/combustion systems. The observer is also experimentally validated on a modern light-duty diesel engine with a dual-loop EGR system.

Volkswagen’s new 2.0 l TDI engine for the most stringent emission standards — Part 1

Having already being launched in Europe in the VW Tiguan and Audi A4, Common Rail engines have been redeveloped to comply with the strictest exhaust fume limits in the world, namely the Tier 2 Bin5 emission legislation in the USA, and will consequently be launched in the VW Jetta there mid-2008. As well as internal engine features like an optimised injection system, a low-pressure exhaust gas recirculation system and a new method of cylinder pressure control, a technical highlight is the implementation of an NOx exhaust gas aftertreatment system. These new engine components require the development of new control algorithms and intensive coordination of parameters for this entirely new combustion process.

Mixed-Source EGR for Enabling High Efficiency Clean Combustion Modes in a Light-Duty Diesel Engine

The source of exhaust gas recirculation (EGR), and consequently composition and temperature, has a significant effect on advanced combustion modes including stability, efficiency, and emissions. The effects of high-pressure loop EGR (HPL EGR) and low-pressure loop EGR (LPL EGR) on achieving high efficiency clean combustion (HECC) modes in a light-duty diesel engine were characterized in this study. High dilution operation is complicated in real-world situations due to inadequate control of mixture temperature and the slow response of LPL EGR systems. Mixed-source EGR (combination of HPL EGR and LPL EGR) was investigated as a reasonable approach for controlling mixture temperature. The potential of mixed-source EGR has been explored using LPL EGR as a 'base' for dilution rather than as a sole source. HPL EGR provides the 'trim' for controlling mixture temperature and has the potential for enabling precise control of dilution targets. This approach also has a benefit where LPL EGR does not provide sufficient dilution for achieving conditions appropriate for HECC operation. The balance of the required dilution could be achieved with HPL EGR mitigating the need for throttling or a LPL EGR pump. The results of this investigation revealed significant differences in engine-out emissions and performance for various EGRmore » sources.« less

Investigation on the flow and heat transfer characteristics of diesel engine EGR coolers

An important goal in diesel engine research is the development of a means to reduce the emissions of nitrogen oxides (NOx). The use of a cooled exhaust gas recirculation (EGR) system is one of the most effective techniques currently available for reducing nitrogen oxides. Since PM (Particulate Matter) fouling reduces the efficiency of an EGR cooler, a tradeoff exists between the amount of NOx and PM emissions, especially at high engine loads. In the present study, we performed engine dynamometer experiments and numerical analyses to investigate how the internal shape of an EGR cooler affects the heat exchanger efficiency. Heat exchanger efficiencies were examined for plain and spiral EGR coolers. The temperature and pressure distributions inside these EGR coolers were obtained in three dimensions using the numerical package program FLUENT.

An experimental study on heat exchange effectiveness in the diesel engine EGR coolers

Both reducing nitrogen oxides (NOx) and particulate matter (PM) emissions from diesel engine and improving fuel consumption are important in meeting government regulations and society needs. Use of the Cooled Exhaust Gas Recirculation (EGR) system is one of the most effective techniques currently available for reducing NOx and PM emissions. However, the EGR system has a trade-off between NOx and PM emissions at high loads. In the present study, engine dynamometer experiments have been performed to investigate the heat exchange effectiveness of EGR coolers with shell & tube-type and stack-type. The results show that the heat transfer effectiveness of the stack-type EGR cooler is 25–50 % higher than that of the shell & tube type due to an increased surface area and a better mixing of the exhaust gas flow.