Modern Diesel Engines Research Articles

Experimental analysis of alternative fuel impact on a new “torque-controlled” light-duty diesel engine for passenger cars

The present paper describes the results of an experimental study performed burning alternative fuels, different per quality and feedstock, in a modern diesel engine compliance the Euro 5 emission standards. Three alternative fuels were tested on the engine and compared with a reference fossil fuel in terms of combustion characteristics, fuel consumption, noise and emissions. The alternative fuels were two biodiesels (RME and SME) and a Fischer–Tropsh (GTL), while the reference fuel was an EU certification diesel fuel. The engine employed in the study was a light-duty diesel engine developed for passenger car and light truck application, and equipped with the new generation ECU able to drive the engine under “torque-controlled” mode by means of instrumented glow-plugs with pressure sensor. The experiments were carried out in a fully instrumented test bench fuelling the engine with the various fuels. The tests were done in a wide range of engine operation points for the complete characterization of the biodiesels performance in the NEDC cycle. Moreover, the trade-off NO x –PM by EGR sweep in the three most critical test points for the engine emission performance was carried out for all fuels. The test methodology was selected carefully in order to evaluate the interaction between the fuel quality and the engine management strategy. The results put in evidence a strong interaction between the alternative fuel quality and the engine control mode highlighting the great benefits reachable by exploiting simultaneously the alternative fuel quality and the flexibility of the new engine management strategies.

New technique for increasing the high-temperature durability of aluminium pistons

The temperatures and pressures in modern day diesel engines are climbing steadily. As a result and in order to have adequate reserves of strength aluminium pistons must feature improved high temperature thermo-mechanical durability. With its DuraBowl technology, the local post-treatment of highly loaded piston regions, Federal-Mogul has been able to increase piston service life by a factor of between four and eight.

Effect of Organometallic Fuel Additives on Nanoparticle Emissions from a Gasoline Passenger Car

Particle size measurements were performed on the exhaust of a car operating on a chassis dynamometer fueled with standard gasoline and gasoline containing low levels of Pb, Fe, and Mn organometallic additives. When additives were present there was a distinct nucleation mode consisting primarily of sub-10 nm nanoparticles. At equal molar dosing Mn and Fe gave similar nanoparticle concentrations at the tailpipe, whereas Pb gave a considerably lower concentration. A catalytic stripper was used to remove the organic component of these particles and revealed that they were mainly solid and, because of their association with inorganic additives, presumably inorganic. Solid nucleation mode nanoparticles of similar size and concentration to those observed here from a gasoline engine with Mn and Fe additives have also been observed from modern heavy-duty diesel engines without aftertreatment at idle, but these solid particles are a small fraction of the primarily volatile nucleation mode particles emitted. The solid nucleation mode particles emitted by the diesel engines are likely derived from metal compounds in the lubrication oil, although carbonaceous particles cannot be ruled out. Significantly, most of these solid nanoparticles emitted by both engine types fall below the 23 nm cutoff of the PMP number regulation.

Solving corrosion problems in biofuels industry

Ethanol is increasingly popular as fuel. It is renewable, cleaner than gasoline, and during the 2008 oil price peak, its costs of production without subsidies actually rivalled those of gasoline. The fuel grade ethanol producers are large consumers of stainless steel, in particular for cookers, fermentation tanks, and distillation columns as well as storage tanks for the finished product. The main reason is that cleanliness is important for the enzymes. However, contaminants play an important role in production as well as storage and distribution. Contaminants are causing a phenomenon called stress corrosion cracking. Biodiesel fuel is a mixture of fatty acid alcohol esters. Modern diesel engines are very sensitive to fuel quality and purity. Biodiesel is unstable, just like butter, which is going rancid in a matter of weeks. Biodiesel degradation is an oxidation process, which among others is speeded up by tiny amounts of metal ions leaching from production and storage vessels. Biodiesel vessels need to be designed in non-degradable materials of construction, as stainless steel. In addition, pretreatment of low cost feedstock and methyl recycling operations use strong acids, which also necessitate stainless steels. Biomass is gaining importance as a source for renewable fuels and hydrogen in addition to heat and electricity. Corrosion issues are numerous and include high temperature corrosion under ash and alkali salt deposits and metal dusting at gasification. Fuel grade ethanol, biodiesel and biomass represent three different corrosion issues, which can be solved using the correct stainless steel.

Model-based fault detection and diagnosis for common-rail injection systems

In order to guarantee the reliability and availability of electronically controlled multi injection systems of modern diesel engines, an improved fault detection and diagnosis gains in importance. For this purpose especially model-based algorithms with signal- and process models can be applied. Thus, Technische Universitat Darmstadt developed a model-based fault detection module for common-rail injection systems among other things in the FVV project “Diagnosis Systems for Diesel Engines” (No. 885 and 952).

Secondary organic aerosol production from modern diesel engine emissions

Abstract. Secondary organic aerosol (SOA) production was observed at significant levels in a series of modern diesel exhaust (DE) aging experiments conducted at the European Outdoor Photoreactor/Simulation Chamber (EUPHORE). The greatest production occurred in DE with toluene addition experiments (>40%), followed by DE with HCHO (for OH radical generation) experiments. A small amount of SOA (3%) was observed for DE in dark with N2O5 (for NO3 radical production) experiments. The analysis for a limited number (54) of polar organic compounds (POC) was conducted to assess the composition of modern DE and the formation of photochemical transformation products. Distinct POC formation in light versus dark experiments suggests the role of OH initiated reactions in these chamber atmospheres. A trend of increasing concentrations of dicarboxylic acids in light versus dark experiments was observed when evaluated on a compound group basis. The four toluene addition experiments in this study were performed at different [tol]o/[NOx]o ratios and displayed an average SOA %yield (in relation to toluene) of 5.3±1.6%, which is compared to past chamber studies that evaluated the impact of [tol]o/[NOx]o on SOA production in more simplified mixtures.

The influence of hydrogen-enriched gas on the performance of lean NO x trap catalyst for a light-duty diesel engine

Modern diesel engines have improved engine fuel economy and significantly reduced nitrogen oxides (NO x ) and particulate matter (PM) emissions achieved by advances in both combustion and exhaust aftertreatment technologies. Recently, it has been shown that the vehicle emissions can be further improved by several catalytic systems including fuel reformers and aftertreatment systems, such as the Lean NO x Trap (LNT). This NO x removal system, called LNT, absorbs NO x under lean exhaust gas conditions and releases NO x under rich conditions. This technology can provide high NO x conversion efficiency, but the right amount of reducing agent should be supplied into the catalytic converter under appropriate conditions. In this work, plasma reformer was used to supply a hydrogen-enriched gas as a NO x reductant. The plasma reforming is one of the most promising on-board reforming technologies, which allows reformates containing H 2 and CO to feed for LNT catalyst efficiently. Partial oxidation is induced by plasma in the fuel reformer and diesel fuel is converted into a hydrogen-enriched gas. The supplying strategy was focused on the maximization of NO x reduction efficiency varying both the total amount of hydrogen-enriched reformate and the ratio of oxygen molecules to in the reformer air-fuel mixture prior to processing at a fixed engine operating condition. The effect of exhaust gas temperature was also studied. The NO x reduction efficiency is closely connected to the amount of supplied fuel to the plasma reformer and the ratio of fuel/air feed rate. The LNT can reduce NO x efficiently with only a 2.6% fuel penalty.

Soy-Biodiesel Impact on NOxEmissions and Fuel Economy for Diffusion-Dominated Combustion in a Turbo−Diesel Engine Incorporating Exhaust Gas Recirculation and Common Rail Fuel Injection

Alternative fuels are gaining importance as a means of reducing petroleum dependence and greenhouse gas emissions. Biodiesel is an attractive renewable fuel; however, it typically results in increased emissions of nitrogen oxides (NOx) relative to petroleum diesel. In order to develop hypotheses for the cause of increased NOx emissions during diffusion-dominated combustion in a modern diesel engine, an effort incorporating both experimental and modeling tasks was conducted. Experiments using a 2007 Cummins diesel engine showed NOx and fuel consumption increases of up to 38% and 13%, respectively, and torque decreases up to 12% for soy-biodiesel. Fuel properties and ignition delay characteristics were implemented in a previously validated engine model to reflect soy-biodiesel. Model predictions are within 3.5%, 7%, and 9.5%, respectively, of experimental engine gas exchange (airflow, charge flow, and exhaust gas recirculation (EGR) fraction), performance (work output, torque, and fuel consumption), and NOx...

Real-gas properties of n-alkanes, O2, N2, H2O, CO, CO2, and H2 for diesel engine operation conditions

The objective of the research outlined in this paper was to develop the analytical approximations for calculating real-gas properties (p-v-T data, thermodynamic functions: internal energy, enthalpy, and entropy, and specific heats) of vapor-phase n-alkanes from C1 (methane) to C14 (normal tetradecane), O2, N2, H2O, CO, CO2, and H2 within the range of pressure 0.05 MPa ≤ p ≤ 20 MPa and temperature 280 K ≤ T ≤ 3000 K aimed for implementation into computational fluid dynamics (CFD)-codes simulating the operation process in modern Diesel engines. The analytical approximations have been developed based on available literature data and on the new equation of state for moderately dense gases. The approximations reported are rather simple and therefore can be used directly in CFD codes. Approximations for mixing rules are also provided.

Nanoparticle Emissions from a Heavy-Duty Engine Running on Alternative Diesel Fuels

We have studied the effect of three different fuels (fossil diesel fuel (EN590); rapeseed methyl ester (RME); and synthetic gas-to-liquid (GTL)) on heavy-duty diesel engine emissions. Our main focus was on nanoparticle emissions of the engine. Our results show that the particle emissions from a modern diesel engine run with EN590, GTL, or RME consisted of two partly nonvolatile modes that were clearly separated in particle size. The concentration and geometric mean diameter of nonvolatile nucleation mode cores measured with RME were substantially greater than with the other fuels. The soot particle concentration and soot particle size were lowest with RME. With EN590 and GTL, a similar engine load dependence of the nonvolatile nucleation mode particle size and concentration imply a similar formation mechanism of the particles. For RME, the nonvolatile core particle size was larger and the concentration dependence on engine load was clearly different from that of EN590 and GTL. This indicates that the formation mechanism of the core particles is different for RME. This can be explained by differences in the fuel characteristics.

Energy and Exergy Balances for Modern Diesel and Gasoline Engines

The aim is here to evaluate the difference between the energy and exergy (or available energy) balances when heat recovery is considered in an internal combustion engine. In the first case, the entropy of the system is not taken into account so that, the maximum useful work recoverable from a system can not be estimated. Then, the second case is much more adapted to estimate heat recovery potential. In this paper, two modern engines are evaluated. First, an up-to-date gasoline engine: three-cylinder, downsized, low friction, then a modern common rail downsized Diesel engine. For each one, two energy and exergy balances are given for two different part-load operating points representative of the NEDC cycle using experimental data from steady state engine test benches. For the Diesel engine, it is shown that effective work represents around 30% and that around 55% of the energy introduced into the combustion chamber is lost (in the form of heat), especially in exhaust gas, in water coolant and oil. But when considering exergy balance, only 12% of the total exergy introduced through the fuel can be recovered, in order to produce useful work. Expecting a 25% exergy recovery efficiency, the effective engine efficiency could be increased by 10%. For the gasoline engine, the increase of the output work could be around 15%.

Differential Impact of Diesel Particle Composition on Pro-allergic Dendritic Cell Function

Diesel exhaust particles (DEP) were described as potent adjuvant in the induction and maintenance of allergic diseases, suggesting that they might play a role in the increase of allergic diseases in the industrialized countries. However, the cellular basis by which these particles enhance allergic immune responses is still a matter of debate. Thus, we exposed immature murine bone marrow-derived dendritic cells (BMDC) to different particles or particle-associated organic compounds in the absence or presence of the maturation stimuli lipopolysaccharide (LPS) and analyzed the cellular maturation, viability, and cytokine production. Furthermore, we monitored the functionality of particle-exposed BMDC to suppress B cell isotype switching to immunoglobulin (Ig) E. Only highly polluted DEP (standard reference material 1650a [SRM1650a]) but not particle-associated organic compounds or less polluted DEP from modern diesel engines were able to modulate the dendritic cell phenotype. SRM1650a particles significantly suppressed LPS-induced IL-12p70 production in murine BMDC, whereas cell-surface marker expression was not altered. Furthermore, SRM1650a-exposed immature BMDC lost the ability to suppress IgE isotype switch in B cells. This study revealed that highly polluted DEP not only interfere with dendritic cell maturation but also additionally with dendritic cell function, thus suggesting a role in T(h)2 immune deviation.

Effect of Open Channel Filter on Particle Emissions of Modern Diesel Engine

Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66–99%, and for accumulation-mode particles the number concentration reduction was 62–69%, both depending on the engine load.

Comparison of Strategies for the Measurement of Mass Emissions from Diesel Engines Emitting Ultra-Low Levels of Particulate Matter

Regulatory methods for the measurement of particulate matter (PM) mass emissions have traditionally been gravimetric. Modern diesel engines equipped with aftertreatment systems, especially Diesel Particulate Filters (DPFs), however, emit much smaller amounts of particulate matter as compared to traditional diesel engines and emit particulate matter with variable compositions. These changes have led to difficulties in measuring PM emissions rates from modern diesel engines using gravimetric methods. Issues associated with diesel PM mass measurement, such as the semi-volatile nature of PM, the interactions with components in the dilution air such as water and ammonia, and the possibility of sampling artifacts, have counteracted a singular focus on mass measurements. These inherent problems may warrant some alternative approaches to characterizing emissions, using methods related to mass and impacts of emissions that can be more accurately defined. The present study provides a comparison and relative precisi...

Effect of injection timing on gasoline homogeneous charge compression ignition particulate emissions

Particulate emissions from homogeneous charge compression ignition (HCCI) engines are often considered as negligible and the measurement of particulate matter (PM) with HCCI combustion systems has been rare. An earlier publication in the literature and the authors' own recently published work suggest that PM emissions from gasoline direct injection (DI) HCCI engines should not be neglected. It has been shown that PM emissions from HCCI engines, although generally lower, can be similar to spark ignition (SI) levels for certain engine conditions, especially in the accumulation mode. The present work shows that although injection timing is effective for control of HCCI, it can have a significant impact on PM emissions. Engine speed also appears to have an impact on PM emissions for the HCCI combustion mode. Typically for HCCI operating at 1500 r/min, the total mass and total number of the PM emissions could be up to six times higher when the fuel is injected during the recompression period compared with the case for injection during the inlet valve open period. Similarly, when the engine was operated in SI mode, an attempt to inject fuel close to induction top dead centre (TDC) made the PM emission noticeably higher, reaching unacceptable levels. The split injection strategy for HCCI mode has been investigated for its effect on PM emissions. It has been found that the PM number concentration for split injection lies between the maximum concentration measured for very early injections (near TDC at recompression) and the minimum concentration measured for the latest injections used (at crank angles near to the inlet valve maximum opening time), with the magnitude of number density varying approximately from 0.2 to 1.2 million/cm3. It is also observed that for split injection the number of particulates in nucleation mode varies less, while the number in accumulation mode level varies within a limit of one order of magnitude; both are dependent on the injection strategy. The shape of the PM distribution is such that the nucleation mode exceeds the number concentration of 1×107 (d N d log Dp) and the accumulation mode falls parabolically to approximately 1×106. For comparison, it can be said that the PM number concentration measured in the authors' engine is approximately one order of magnitude lower in accumulation mode than the level for a typical modern diesel engine.

A Model From First Principles of the Radial Heat Flux in a Cylinder Bore of a Modern Diesel Engine

A simple model from first principles has been developed to estimate the heat transferred from the piston rings and skirt to the cylinder wall. The model considers the various forms in which heat is transferred from the combustion gases to the containing walls, namely, convection and radiation between the gases and wall surface, and conduction from piston rings and skirt through the oil film. The model also includes frictional heat generation by the rings and skirt as a result of the piston movement. Results presented in this paper show that the heat flux predicted by the model on the thrust side of the bore, at an engine speed of 4000 rpm and engine load of 100% of the limiting torque, was generally of the same order of magnitude as the heat flux estimated from experimental measurements. They also demonstrated that in the process of heat transfer from combustion gases to the cylinder wall, convection and radiation of heat have their greatest influence on the total heat flux in the top section of the cylinder bore and provide a contribution of approximately 25% over the rest of the stroke. However, the distribution of heat flux in the middle and bottom parts of the stroke shows that the main mechanism of heat transfer is conduction from the piston assembly.

Trends in Performance Characteristics of Modern Automobile SI and Diesel Engines

Trends in Performance Characteristics of Modern Automobile SI and Diesel Engines

Gain-scheduled model-based feedback control of the air/fuel ratio in diesel engines

This paper investigates the adoption of an innovative closed-loop control of the air/fuel ratio (AFR) in modern diesel engines. The in-cylinder AFR is in fact a critical quantity responsible for the formation of NO x and particulate matter emission. Two approaches are investigated for the design of a gain-scheduled AFR controller, that are based on the internal model control structure and on the H ∞ design method. In addition, two feedforward controllers are investigated for improving the tracking quality of the system. In terms of tracking performance and driveability, the proposed AFR controllers at least match the series production EGR controller. However, due to the fact that an AFR controller uses information obtained after the combustion process, it can also deal with the drift of sensors and actuators involved in the control loop.

Comparative analysis of a DI diesel engine fuelled with biodiesel blends during the European MVEG-A cycle: Preliminary study (I)

The present work consists of introducing the tests and facilities used to perform a comparative analysis of a diesel engine working with different blends of biodiesel fuel during the New European Driving Cycle. Furthermore, as a preliminary study, it was interesting to know the effects of biodiesel fuel on a common-rail high pressure injection system, those more useful in modern light duty diesel engines, as a consequence of its different physicochemical properties compared with conventional diesel fuel. As the real goal of the study is to compare fairly performance and emissions from the engine, it was essential to know any injection effects owed to fuel's own characteristics that finally would affect those parameters that will be evaluated. A complete fuel characterization for diesel and biodiesel fuels, as the EN 590 and the EN 14214 standard specifications, was performed in order to quantify the differences between both fuels. A priori, it could be thought that viscosity and density values will be the most significant parameters capable of altering the injection rate. As positive results, it was obtained that the common-rail high pressure injection system was totally blind in the injection rate measurements, even the significant differences between both fuels, taking into account the counterbalancing effects generated by two parameters mentioned before. The second part of the study deals with engine performance and pollutant emissions on an unmodified common-rail turbocharged diesel engine running with biodiesel fuel blends during the New European Driving Cycle.

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.