Showing papers on "Diesel engine published in 2000"

Emissions from nine heavy trucks fueled by diesel and biodiesel blend without engine modification

Abstract: Biodiesel, a fuel that can be made from renewable biological sources such as vegetable oils or animal fats, has been recognized recently as an environment friendly alternative fuel for diesel engines. In this paper, we describe a study that compared exhaust emissions from in-use heavy trucks fueled with a biodiesel blend with those from trucks fueled with petroleum diesel. The biodiesel blend tested is a mixture of 35% biodiesel and 65% petroleum diesel, a blend designated as B35. The study is based on the field test results from West Virginia University's Transportable Heavy Duty Chassis Dynamometer Emissions Testing Laboratory and sponsored by the U.S. Department of Energy. The heavy trucks we tested performed well when the originally equipped compression-ignition engine (diesel engine) was fueled with B35 without any engine modifications. Fuel economy (in terms of gallon per mile) of the two fuels was about the same. The emissions test results have shown that the heavy trucks fueled by B35 emitted sign...

Constructive Lyapunov control design for turbocharged diesel engines

Abstract: Presents a control design method for diesel engines equipped with a variable geometry turbocharger and an exhaust gas recirculation valve. Our control objective is to regulate the air-fuel ratio and the fraction of recirculated exhaust gas to their respective set points that depend on engine operating conditions. Interactions between the two actuators and nonlinear behavior of the system make the problem difficult to handle using classical control design methods. Instead, we employ a control Lyapunov function (CLF) based nonlinear control design method because it possesses a guaranteed robustness property equivalent to gain and phase margins. The CLF is constructed using input-output linearization of a reduced order diesel engine model. The controller has been tested in simulations on the full order model as well as experimentally in the dynamometer test cell.

EGR-VGT control schemes: experimental comparison for a high-speed diesel engine

Abstract: Variable-geometry turbochargers (VGTs) are employed in high-end diesel engines. These VGTs also help in controlling the trade-offs in emissions performance. Exhaust gas recirculation (EGR) is used to dilute the combustion mixture, resulting in lower peak combustion temperatures and a lower oxygen concentration and hence lower NOx emissions. In this article, we compare some of the control methodologies previously presented and some not yet presented to evaluate their benefits experimentally. We do not include any new theory. Rather we refer to other sources for the development of the controllers evaluated. We present an objective comparison of advanced control methodologies on a complex industrial problem with widespread applications. The control methodologies discussed are essentially system based, i.e., the initial controller is developed on an engine model.

Effects of Biodiesel, Biodiesel Blends, and a Synthetic Diesel on Emissions from Light Heavy-Duty Diesel Vehicles

Abstract: Over the past several years, there has been increased interest in reformulated and alternative diesel fuels to control emissions and provide energy independence. In the following study, a California diesel fuel was compared with neat biodiesel, an 80% California diesel/20% biodiesel blend, and a synthetic diesel fuel to examine the effects on emissions. Chassis dynamometer tests were performed on four light heavy-duty diesel trucks using each of the four fuels. The results of this study showed that biodiesel, the biodiesel blends, and the synthetic diesel produced generally lower THC and CO emissions than California diesel. NOx emissions were comparable over most of the fuel/vehicle combinations, with slightly higher NOx emissions found for the two noncatalyst vehicles on 100% biodiesel. Particulate emissions were slightly higher for two test vehicles and significantly higher for a third test vehicle on the biodiesel fuels. Chemical analyses showed elemental and organic carbon to be the primary constituen...

The effects of exhaust gas recirculation on diesel combustion and emissions

Abstract: An investigation was conducted with the aim of identifying and quantifying the effects of exhaust gas recirculation (EGR) on diesel engine combustion and exhaust emissions. Five effects of EGR were identified and investigated experimentally: the reduction in oxygen supply to the engine, participation in the combustion process of carbon dioxide and water vapour present in the EGR, increase in the specific heat capacity of the engine inlet charge, increased inlet charge temperature and reduction in the inlet charge mass flowrate arising from the use of hot EGR. The experimental methodology developed allowed each one of these effects to be investigated and quantified separately. The investigation was carried out on a high-speed, direct injection diesel engine, running at an intermediate speed and load. A limited number of tests were also conducted in an optically accessible diesel engine, which established the effects of EGR on local flame temperature. Finally, tests were conducted with simulated EGR...

Characterization of Particles from a Current Technology Heavy-Duty Diesel Engine

Abstract: The physical properties, chemical properties, and morphology of particles from a current technology diesel engine run under steady-state conditions were determined during five campaigns across three calendar years. Concentrations of particulate matter, NOx, HC, CO, and CO2 measured at a fixed sampling position were found to be repeatable between different campaigns. However, particle size distributions and number concentrations were significantly affected by dilution conditions. Particle density, estimated using a volume size distribution estimated from an ELPI together with measured mass, was found to be below 1 g/cm3 at nonzero loads, but this is explained by an overestimation of volume by the ELPI due to particle fractal properties. Particle phase SO42-, NO3-, PAH, organic carbon, and elemental carbon were found to vary with engine operating modes. Particles emitted from a modern diesel engine had similar cluster structures to those from old engines but consisted of smaller basic particles when analyze...

Comparisons of diesel spray liquid penetration and vapor fuel distributions with in-cylinder optical measurements

Abstract: The performance of two spray models for predicting liquid and vapor fuel distribution, combustion and emissions is investigated. The model predictions are compared with extensive data from in-cylinder laser diagnostics carried out in an optically accessible heavy-duty, D. I, diesel engine over a wide range of operating conditions. Top-deadcenter temperature and density were varied between 800 K and 1100 K and 11.1 and 33.2 kg/m 3 , respectively. Two spray breakup mechanisms were considered: due to Kelvin-Helmholtz (KH) instabilities and to Rayleigh-Taylor (RT) instabilities, Comparisons of a wide range of parameters, which include in-cylinder pressure, apparent heat release rate, liquid fuel penetration, vapor distribution and soot distribution, have shown that a combination of the KH and the RT mechanisms gives realistic predictions, In particular, the limited liquid fuel penetration observed experimentally was captured by including these two competing mechanisms in the spray model. Furthermore, the penetration of the vapor fuel ahead of the liquid spray was also captured. A region of high soot concentration at the spray tip was observed experimentally and also predicted by the KH-RT spray breakup model.

Combustion and exhaust gas emission characteristics of a diesel engine dual-fueled with natural gas

Abstract: This paper deals with a diesel engine dual-fueled with natural gas. This system can achieve a high thermal efficiency at higher loads by utilizing the premixed lean natural gas mixture ignited by pilot-injected diesel fuel. At low loads, however, high THC emission and low thermal efficiency were observed. To resolve these problems, effects of EGR and intake heating with an exhaust to intake heat exchanger on engine performance and exhaust gas emissions were investigated, especially at low loads. In addition, 3-CFD simulations were conducted to analyze the combustion process in the combustion chamber, using the KIVA-3 code. The result indicates that thermal efficiency and THC emission at lower loads can be improved by intake air heating combined with EGR.

Effects of fuel cetane number and aromatics on combustion process and emissions of a direct-injection diesel engine

Abstract: This study investigated the effects of fuel properties on combustion characteristics and emissions such as NOx. THC, smoke and particulate in a direct-injection diesel engine. Cetane number and aromatic content of fuels were varied independently. The results showed that reducing cetane number resulted in the increase of NOx and the decrease of particulate at high load. The aromatic content had little effect on combustion characteristics. However, increasing aromatic content for high cetane number fuel resulted in high NOx and particulate emissions. For low cetane number fuel, increasing aromatic content produced high THC emission at retarded injection timing. In the case of high injection pressure, fuel properties showed little effect on particulate emissions.

Low pressure EGR system for diesel engines

Abstract: A low pressure EGR system suitable for use as a passive retrofit system is disclosed for moving vehicles equipped with a diesel engine. The EGR loop inlet is positioned upstream of the exhaust particulate filter and downstream of the turbine to utilize backpressure created by the exhaust particulate filter to insure EGR flow in the loop. A catalyzed soot filter in communication with the EGR pickup insures cleansed EGR gases at the EGR return downstream of the air filter and upstream of the compressor. A corrugated EGR line provides cooling of the EGR gases.

Diesel Engine Combustion of Biomass Pyrolysis Oils

Abstract: To investigate their ignition delay and combustion behavior, experiments with two biomass pyrolysis oils and No. 2 diesel fuel were performed in a direct injection diesel engine. It was found that while the indicated thermal efficiency of both pyrolysis oils equaled that of the diesel fuel, they exhibited excessive ignition delays and required a moderate degree of combustion air preheating to ignite reliably. Despite the longer ignition delays associated with the pyrolysis oils, the cylinder pressure rise rates were significantly less than with No. 2 diesel fuel. Experimental ignition delay and heat release rates were interpreted using a phenomenological spray combustion model. Using a three parameter fit for vaporization, ignition, and combustion rate, the model showed that the longer ignition delays of the bio-oils result from slow chemistry relative to diesel fuel. The model also showed that the heat release profiles of the bio-oils are consistent with slow combustion chemistry and rapid mixing relativ...

Turbulent Transient Gas Injections

Abstract: Compressible transient turbulent gaseous jets are formed when natural gas is injected directly into a diesel engine. Multi-dimensional simulations are used to analyze the penetration, mixing, and combustion of such gaseous fuel jets. The capability of multi-dimensional numerical simulations, based on the k-e turbulence model, to reproduce the experimentally verified penetration rate of free transient jets is evaluated. The model is found to reproduce the penetration rate dependencies on momentum, time, and density, but is more accurate when one of the k-e coefficients is modified. The paper discusses other factors affecting the accuracy of the calculations, in particular, the mesh density and underexpanded injection conditions. Simulations are then used to determine the impact of chamber turbulence, injection duration, and wall contact on transient jet penetration. The model also shows that gaseous jets and evaporating diesel sprays with small droplet size mix at much the same rate when injected with equivalent momentum injection rate.

Emissions reductions using hydrogen from plasmatron fuel converters

Abstract: Substantial progress in engine emission control is needed in order to meet present and proposed regulations for both spark ignition and diesel engines. Tightening regulations throughout the world reflect the ongoing concern with vehicle emissions. Recently developed compact plasmatron fuel converters have features that are suitable for onboard production of hydrogen for both fuel pretreatment and for exhaust aftertreatment applications. Systems that make use of these devices in conjunction with aftertreatment catalysts have the potential to improve significantly prospects for reduction of diesel engine emissions. Plasmatron fuel converters can provide a rapid response compact means to transform efficiently a wide range of hydrocarbon fuels into hydrogen rich gas. They have been used to reform natural gas [Bromberg1], gasoline [Green], diesel [Bromberg2] and hard-to-reform biofuels [Cohn1] into hydrogen rich gas (H2 + CO). The development of these devices has been pursued for the purpose of reducing engine exhaust pollutants by providing hydrogen rich gas for combustion in spark ignition and possibly diesel engines, as shown in Figure 1 [Cohn2]. Recent developments in compact plasmatron reformer design at MIT have resulted in substantial decreases in electrical power requirements. These new developments also increase the lifetime of the electrodes.

Cytotoxic and mutagenic effects, particle size and concentration analysis of diesel engine emissions using biodiesel and petrol diesel as fuel.

Abstract: Diesel engine exhaust particles (DEP) contribute substantially to ambient air pollution. They cause acute and chronic adverse health effects in humans. Biodiesel (rapeseed oil methyl ester. RME) is used as a "green fuel" in several countries. For a preliminary assessment of environmental and health effects of RME, the particulate-associated emissions from the DEP of RME and common fossil diesel fuel (DF) and their in vitro cytotoxic and mutagenic effects were compared. A test tractor was fuelled with RME and DF and driven in a European standard test cycle (ECE R49) on an engine dynamometer. Particle numbers and size distributions of the exhausts were determined at the load modes "idling" and "rated power". Filter-sampled particles were extracted and their cytotoxic properties tested using the neutral red assay. Mutagenicity was tested using the Salmonella typhimurium/microsome assay. Despite higher total particle emissions, solid particulate matter (soot) in the emissions from RME was lower than in the emissions from DF. While the size distributions and the numbers of emitted particles at "rated power" were nearly identical for the two fuels, at "idling" DF emitted substantially higher numbers of smaller particles than RME. The RME extracts caused fourfold stronger toxic effects on mouse fibroblasts at "idling" but not at "rated power" than DF extracts. The extracts at both load modes were significantly mutagenic in TA98 and TA100. However, extracts of DF showed a fourfold higher mutagenic effect in TA98 (and twofold in TA100) than extracts of RME. These results indicate benefits as well as disadvantages for humans and the environment from the use of RME as a fuel for tractors. The lower mutagenic potency of DEP from RME compared to DEP from DF is probably due to lower emissions of polycyclic aromatic compounds. The higher toxicity is probably caused by carbonyl compounds and unburned fuel, and reduces the benefits of the lower emissions of solid particulate matter and mutagens from RME.

Effects of Direct Water Injection on DI Diesel Engine Combustion

Abstract: The effects of in-cylinder water injection on a direct injection (DI) Diesel engine were studied using a computational fluid dynamics (CFD) program based on the Kiva-3v code. The spray model is validated against experimental bomb data with good agreement for vapor penetration as a function of time. It was found that liquid penetration increased approximately 35% with 23% of the fuel volume replaced by water, due mostly to the increase in latent heat of vaporization. Engine calculations were compared to experimental results and showed very good agreement with pressure, ignition delay and fuel consumption. Trends for emissions were accurately predicted for both 44% and 86% load conditions. Engine simulations showed that the vaporization of liquid water as well as a local increase in specific heat of the gas around the flame resulted in lower Nitrogen Oxide emissions (NOx) and soot formation rates. Using stratified fuel-water injection increases soot at 86% loads due in part to late injection. Because NOx decreased at all loads, the injection timing can be advanced to minimize fuel consumption and soot.

Simulation of combustion in direct injection diesel engines using a eulerian particle flamelet model

Abstract: An overview of flamelet modeling for turbulent non-premixed combustion is given. A short review of previous contributions to simulations of direct injection (DI) diesel engine combustion using the representative interactive flamelet concept is presented. A surrogate fuel consisting of 70% (liquid volume) n -decane and 30% α -methylnaphthalene is experimentally compared to real diesel fuel. The similarity of their physical and chemical properties is shown to result in a very similar combustion process for both fuels. The mathematical derivation for the Eulerian particle flamelet model is outlined. A strategy based on physical arguments is described for subdividing the computational domain and assigning these domains to different flamelet histories associated with Eulerian marker particles. For each of these marker particles, a transport equation has to be solved. Experiments conducted with an Audi DI diesel engine equipped with a piezo injector and running with diesel fuel are compared to simulations using the surrogate fuel. The use of multiple flamelets, each having a different history, significantly improves the description of the ignition phase, leading to a better prediction of pressure, heat release, and exhaust emissions such as soot and NO x . The effect of the number of flamelet particles on the predictions is discussed.

Turbocharger and EGR System

Abstract: An exhaust gas recirculation system for an internal combustion engine. The present invention includes a turbocharger, restrictor valve, and exhaust gas recirculation valve. The restrictor valve is upstream of the turbine of the turbocharger, and restricts the flow of exhaust gas into the turbine. This restriction results in an increase in pressure of the exhaust gas provided to the restrictor valve. The increased pressure exhaust gas is provided to the inlet of an exhaust gas recirculation valve which may be actuatable independently of the actuation of the restrictor valve. The restrictor valve may be modulated until exhaust pressure is greater than the pressure of the intake gas. The restrictor valve creates a pressure differential suitable for recirculating a portion of exhaust gas through the EGR valve and into the intake manifold of the engine. The restrictor valve may also be operated without recirculation of exhaust gas, such as during cold starting of a diesel engine so as to increase the load on the engine and decrease the warm-up time of the engine. Some embodiments of the present invention utilize an electronic controller for operating the restrictor valve and the EGR valve.

A fuel-based assessment of off-road diesel engine emissions.

Abstract: The use of diesel engines in off-road applications is a significant source of nitrogen oxides (NOx) and particulate matter (PM10). Such off-road applications include railroad locomotives, marine vessels, and equipment used for agriculture, construction, logging, and mining. Emissions from these sources are only beginning to be controlled. Due to the large number of these engines and their wide range of applications, total activity and emissions from these sources are uncertain. A method for estimating the emissions from off-road diesel engines based on the quantity of diesel fuel consumed is presented. Emission factors are normalized by fuel consumption, and total activity is estimated by the total fuel consumed. Total exhaust emissions from off-road diesel equipment (excluding locomotives and marine vessels) in the United States during 1996 have been estimated to be 1.2 x 10(9) kg NOx and 1.2 x 10(8) kg PM10. Emissions estimates published by the U.S. Environmental Protection Agency are 2.3 times higher for both NOx and exhaust PM10 emissions than estimates based directly on fuel consumption. These emissions estimates disagree mainly due to differences in activity estimates, rather than to differences in the emission factors. All current emission inventories for off-road engines are uncertain because of the limited in-use emissions testing that has been performed on these engines. Regional- and state-level breakdowns in diesel fuel consumption by off-road mobile sources are also presented. Taken together with on-road measurements of diesel engine emissions, results of this study suggest that in 1996, off-road diesel equipment (including agriculture, construction, logging, and mining equipment, but not locomotives or marine vessels) was responsible for 10% of mobile source NOx emissions nationally, whereas on-road diesel vehicles contributed 33%.

Control method for turbocharged diesel engines having exhaust gas recirculation

Abstract: A method of controlling the airflow into a compression ignition engine having an EGR and a VGT. The control strategy includes the steps of generating desired EGR and VGT turbine mass flow rates as a function of the desired and measured compressor mass airflow values and exhaust manifold pressure values. The desired compressor mass airflow and exhaust manifold pressure values are generated as a function of the operator-requested fueling rate and engine speed. The EGR and VGT turbine mass flow rates are then inverted to corresponding EGR and VGT actuator positions to achieve the desired compressor mass airflow rate and exhaust manifold pressure. The control strategy also includes a method of estimating the intake manifold pressure used in generating the EGR valve and VGT turbine positions.

Control method for a variable geometry turbocharger in a diesel engine having exhaust gas recirculation

Abstract: A method of estimating the actuator position of a variable geometry turbocharger (VGT) of a compression ignition engine having an exhaust gas recirculation (EGR) system. The method includes the steps of determining the exhaust manifold temperature (T 2 ), determining the mass flow rate (W 2t ) through the turbocharger turbine, determining the exhaust manifold pressure (p 2 ), determining the turbine back-pressure (p exs ), and generating a VGT actuator position estimate (α vgt ) as a function of W 2t , T 2 , p 2 , and p exs . The estimated VGT actuator position is then used to generate an error term indicative of the difference between the estimated and desired VGT actuator position. The error term can then be used to drive the VGT actuator to its desired position to regulate the intake manifold pressure.

Neural network modelling of the emissions and performance of a heavy-duty diesel engine

Abstract: Internal combustion engines are being required to comply with increasingly stringent government exhaust emissions regulations. Compression ignition (CI) piston engines will continue to be used in cost-sensitive fuel applications such as in heavy-duty buses and trucks, power generation, locomotives and off-highway applications, and will find application in hybrid electric vehicles. Close control of combustion in these engines will be essential to achieve ever-increasing efficiency improvements while meeting increasingly stringent emissions standards. The engines of the future will require significantly more complex control than existing map-based control strategies, having many more degrees of freedom than those of today. Neural network (NN)-based engine modelling offers the potential for a multidimensional, adaptive, learning control system that does not require knowledge of the governing equations for engine performance or the combustion kinetics of emissions formation that a conventional map-based engine model requires. The application of a neural network to model the output torque and exhaust emissions from a modern heavy-duty diesel engine (Navistar T444E) is shown to be able to predict the continuous torque and exhaust emissions from a heavy-duty diesel engine for the Federal heavy-duty engine transient test procedure (FTP) cycle and two random cycles to within 5 per cent of their measured values after only 100 min of transient dynamometer training. Applications of such a neural net model include emissions virtual sensing, on-board diagnostics (OBD) and engine control strategy optimization. (A)

The Influence of Additives on the Size Distribution and Composition of Particles Produced by Diesel Engines

Abstract: Measurements with different diesel engines and fuel additives permit a characterisation of the aerosol of a diesel engine under the influence of fuel additives. Combined with chemical analysis and gravimetry a clear picture of the size range and composition of the emitted particles is oblained. Emission factors computed by gravimetry and coulometry correlate well. A correlation is found between the minimum additive concentration needed to induce exhaust particles consisting of additive products, and the elemental carbon emission factor of the engines. It provides informalion for optimising the exhaust cleaning system.