Showing papers on "Diesel engine published in 1995"

Chronic Inhalation Exposure of Wistar Rats and two Different Strains of Mice to Diesel Engine Exhaust, Carbon Black, and Titanium Dioxide

Abstract: Wistar rats were exposed for 2 yr to diesel engine exhaust, carbon black (Printex 90, Degussa, FR. G), and ultraline TiO2 (P25, Degussa, FRG) and were subsequently kept in clean air for 6 mo. Particle exposure concentration was increased during the course of the experiment for carbon black and TiO2 to reach particle lung loads similar to those found in the diesel soot-exposed rats. The average particle exposure concentrations for diesel soot, carbon black, and TiO2 were 7, 11.6, and 10 mg/m3, respectively. Lung tumor rates in these rats increased with increasing cumulative particle exposure (mg/m3 x h) independent of the type of particle employed. The exposure to 2.5 mg/m1 diesel soot also induced a significantly increased lung tumor rate, but 0.8 mg/m3 diesel soot did not. With this study, it could be demonstrated that the carbon core of diesel soot is mainly responsible for the occurrence of diesel engine exhaust-related lung tumors; the role of diesel soot-attached polycyclic aromatic hydrocarb...

Turbocharged Diesel Engine Modeling for Nonlinear Engine Control and State Estimation

Abstract: Engine models that are used for nonlinear diesel engine control, state estimation, and model-based diagnostics are presented in this paper. By collecting, modifying, and adding to current available engine modeling techniques, two diesel engine models, a mean torque production model and a cylinder-by-cylinder model, are summarized for use in the formulation of control and state observation algorithms. In the cylinder-by-cylinder model, a time-varying crankshaft inertia model is added to a cylinder pressure generator to simulate engine speed variations due to discrete combustion events. Fuel injection timing and duration are control inputs while varying engine speed, cylinder pressure, and indicated torque are outputs from simulation. These diesel engine models can be used as engine simulators and to design diesel engine controllers and observers.

Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics

Abstract: Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the ``heavy-duty`` size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel. Combustion and soot formation are almost identical for both fuels. Ignition and early combustion were studied by imaging the natural chemiluminescence using a calibrated intensified video camera. Early soot development was investigated via luminosity imaging and simultaneous planar imaging of laser-induced incandescence (LII) and elastic scattering. The latter provide relative soot concentrations and particle size distributions. Data show that ignition occurs at multiple points across the downstream region of all the fuel jets prior to first apparent heat release well before any soot luminosity occurs. Quantitative vapor-fuel/air mixture images in the leading portion of the jet are also presented and discussed with respect to the early combustion data. The first soot occurs at random locations, and shortly thereafter, small soot particles develop throughout the cross section of the leading portion of the jet. Data indicate that this soot arises frommore » the fuel-rich premixed burn. Then, significantly larger soot particles appear around the periphery of the jet, presumably from the initial diffusion combustion. By the end of the premixed burn, the soot has developed a distribution pattern of a higher concentration toward the front of the jet and a lower concentration upstream, with the larger-sized soot particles being generally confined to the periphery of the jet.« less

In-situ oil analyzer and methods of using same, particularly for continuous on-board analysis of diesel engine lubrication systems

Abstract: A method and apparatus for detecting the degree of deterioration of a lubricating oil for an operating machine includes a grid-like capacitive sensor (20) that uses the lubricating oil as a dielectric medium. A magnetic field is imposed upon the oil to attract ferromagnetic wear particles into the vicinity of the sensor. Preferably, the magnetic field is generated by at least two independently controlled electromagnet windings (26, 28) aligned such that the magnetic field produced by each winding acts upon the wear particles. A plurality of capacitance measurements are taken at periodic intervals at each of several magnet operational states for respective classification and analysis. All windings may be simultaneously de-energized for release of captured particles back in to an oil circulation stream and to clean the capacitative sensor grid of accumulated particulates.

The effect of TDC temperature and density on the liquid-phase fuel penetration in a D.I. Diesel engine

Abstract: A parametric study of the liquid-phase fuel penetration of evaporating Diesel fuel jets has been conducted in a directinjection Diesel engine using laser elastic-scatter imaging. The experiments were conducted in an optically accessible Diesel engine of the ``heavy-duty`` size class at a representative medium speed (1200 rpm) operating condition. The density and temperature at TDC were varied systematically by adjusting the intake temperature and pressure. At all operating conditions the measurements show that initially the liquid fuel penetrates almost linearly with increasing crank angle until reaching a maximum length. Then, the liquid-fuel penetration length remains fairly constant although fuel injection continues. At a TDC density of 16.6 kg/m{sup 3} and a temperature of about 1000 K the maximum penetration length is approximately 23 mm. However, it varies significantly as TDC conditions are changed, with the liquid-length being less at higher temperatures and at higher densities. The corresponding apparent heat release rate plots are presented and the results of the liquid-phase fuel penetration are discussed with respect to the ignition delay and premixed bum fraction.

Method of automatically initiating regeneration of a particulate filter of a diesel engine with a rail injection system

Abstract: An automatic regeneration initiating method presenting, in addition to the main injection phase, an auxiliary post-injection phase for injecting a given quantity of fuel directly into the cylinders during the expansion stroke when the temperature in the combustion chamber is still high enough for its combustion, so as to increase the temperature of the exhaust gas and initiate combustion of the filtered particulate. By appropriately regulating the amount of fuel injected and the timing of the post-injection phase, incomplete combustion products are formed for assisting combustion of the dry particulate and lowering its ignition temperature.

Compact auxiliary power system for heavy-duty diesel engines and method

Abstract: An auxiliary power assembly (5) for use with a heavy-duty diesel engine (8) of the type used in the trucking industry and including a small auxiliary diesel engine (9), an air compressor (10), a compressed air accumulator (17) fluid coupled to the air compressor (10), and a pneumatic starter (21) fluid coupled to the accumulator (17) and mechanically coupled to start the heavy-duty diesel engine (8). The auxiliary power assembly (5) further drives: a coolant pump (51) connected to circulate coolant between the auxiliary engine (9) and main diesel engine (8), a refrigerant compressor (41) formed to pump air conditioning fluid from the main diesel engine air conditioning system to the vehicle cab (70), and a pre-oiler pump (83) used to pressurize lubricating oil in the main engine (8). A method of operating the overall assembly and for retrofitting an existing heavy-duty diesel engine (8) with the auxiliary power assembly (5) also are disclosed.

Diesel engine operating method

Abstract: The method involves using an exhaust gas feedback device (6) between the exhaust (3) and induction (2) systems. The feedback device is actuated by a control element activated by an auxiliary force-actuated drive depending on signals from an electronic controller. An engine controller (4) enables weakness/richness control of the diesel engine (1) depending on its operating parameters. A storage catalyser (12) in the exhaust system adsorbs, desorbs and reduces nitrogen oxides. A sensor (15) downstream of the catalyser detects the NOx conc. in the exhaust flow. When a NOx threshold value varying with speed and load is reached the operating mode is changed over from a lambda value of greater than unity to one less than unity.

Catalyst for purification of diesel engine exhaust gas

Abstract: A catalyst for purification of diesel engine exhaust gas is disclosed which comprises having (A) a catalytic component comprising the two elements of iron and manganese and a refractory inorganic oxide and optionally an alkaline earth element and/or a rare earth element and (B) a catalytic component comprising at least one noble metal selected from the group consisting of palladium, platinum, and rhodium and a refractory inorganic oxide and optionally copper deposited in the form of a single layer on a refractory three-dimensional structure. This catalyst is capable of removing such harmful components as carbonaceous particulates, unburned hydrocarbons, and carbon monoxide from the diesel engine exhaust gas and, moreover, suppress the formation of sulfates from sulfur dioxide.

Survival of Polycyclic Aromatic Hydrocarbons during Diesel Combustion.

Abstract: The application of a radiotracer technique to investigate the sources of polycyclic aromatic hydrocarbons (PAH) in diesel exhaust emissions is described. In separate experiments, 14 C-radiolabeled naphthalene, 2-methylnaphthalene (2-MeNp), fluorene, pyrene, and benzo[a]pyrene (B[a]P) were each added to diesel fuel, which was combusted in a 2-L direct injection Perkins Prima diesel engine. Exhaust samples were collected using a novel exhaust gas sampling device designed for sampling organic species in automobile exhaust emissions. Survivals for these PAH were 0.87% for fluorene, 0.54% for 2-MeNp, 0.47% for naphthalene, 0.17% for pyrene, and 0.04% for B[a]P. A linear relationship was observed between the extent to which individual PAH survived combustion and the energy level of the lowest unoccupied molecular orbital (LUMO) of the molecule. LUMO energy levels for each molecule were calculated from Huckel molecular orbital theory. The relationship observed in the current experiment suggests that, forthese PAH and under steady-state engine conditions, it is the chemical kinetics of reactions occurring in the combustion chamber as opposed to thermodynamic stabilities that determine the extent of PAH survival during diesel combustion. Using this relationship, it should be possible to predict the extent of PAH survival in diesel emissions from a knowledge of the PAH composition of the fuel.

The reduction of nitrogen oxides emissions from vehicular diesel engines

Abstract: The present invention relates to a process for reducing nitrogen oxides emissions from a diesel engine which comprises preparing an emulsion (80) of water in diesel fuel which contains a catalytically effective amount of catalyst composition (26) and a lubricity additive and supplying said emulsion to a diesel engine for combusting therein, whereby combustion of the emulsion leads to a reduction in the nitrogen oxides emissions from the diesel engine when compared with combustion of diesel fuel alone.

Process for cooling diesel engine exhaust gases

Abstract: A process and a suitable arrangement for cooling diesel engine exhaust gases in an exhaust gas recirculation system is provided. In order to be able to avoid a contamination of the heat exchanger as well as a resulting required regenerating of the latter in the case of a cooling of the hot exhaust gas flow over a large temperature range, the cooling of the hot exhaust gas flow is carried out in at least two steps in that the exhaust gas flow flows successively through two heat exchangers which are each adapted to the corresponding cooling temperature range. By adapting the heat exchangers to specific small temperature ranges, even hot exhaust gas flows of up to 800° C. can be cooled to a desired low temperature by the series connection of a corresponding number of different heat exchangers, without causing significant contaminations of the exhaust gas cooling arrangement by exhaust gas particles. By the use of known heat exchangers, the construction of the exhaust gas cooling system becomes particularly reasonable with respect to cost.

Fueling a Diesel Engine with Methyl-ester Soybean Oil

Abstract: The Agricultural Engineering Department at the University of Missouri-Columbia has fueled a 1991 and a 1992 Dodge pickup 5.9 L (360 in.3) Cummins engine with methyl-ester soybean oil (soydiesel) for more than 80 467 km (50,000 mile). The 1991 pickup has been driven approximately 48 280 km (30,000 mile) and the 1992 pickup has been driven approximately 32 187 km (20,000 mile). Fueling the engines with 100% soydiesel increased engine power by 3% (1991 engine) and reduced power by 7% (1992 engine). The pickups averaged more than 6.9 km/L (16.7 mile/gal). Analysis of engine lubrication oil suggested that the engines were wearing at a normal rate. The black exhaust smoke normally observed when a diesel engine accelerates was reduced by 86% when the diesel engine was fueled with 100% soydiesel. Increased EPA exhaust emissions requirements for diesel engines have created much interest in the use of soydiesel as a fuel for diesel engines.

ULEV potential of a DI/TCI diesel passenger car engine operated on dimethyl ether

Abstract: This paper describes a feasibility test program on a 2 liter, 4 cylinder DI/TCI passenger car engine operated on the new alternative fuel Dimethyl Ether (DME) with the aim of demonstrating its potential of meeting ULEV (ultra low emission vehicle) emissions (0.2 g/mi NOx in the FTP 75 test cycle) when installed in a full size passenger car. Special attention is drawn to the fuel injection equipment (FIE) as well as combustion system requirements towards the reduction of NOx and combustion noise while keeping energetic fuel consumption at the level of he baseline DI/TCI diesel engine. FIE and combustion system parameters were optimized on the steady state dynamometer by variation of a number of parameters, such as rate of injection, number of nozzle holes, compression ratio, piston bowl shape and exhaust gas recirculation. The paper presents engine test results achieved with DME under various operating conditions and compares these results to those achieved with the diesel version of the same engine.The FTP 75 cycle results were projected from steady state engine maps using a vehicle simulation program taking into account vehicle data and road resistance data of a given vehicle.The cycle results are also compared to actual chassis dynamometer resultsmore » achieved with the diesel version of the same engine installed in the same vehicle.the passenger car DI/TCI engine adapted for and operated on DME shows very promising results with respect to meeting ULEV NOx emissions without any soot emissions and without the need for a DENOX catalyst. DME fuel consumption on energy basis can be kept very close to the DI diesel value. An oxidation catalyst will be necessary to meet the stringent CO and HC ULEV emission limits.« less

Analysis of combustion and pollutants formation in a direct injection diesel engine using a multi-zone model

Abstract: A two-dimensional multi-zone model for the calculation of the closed cycle of a direct injection (DI) diesel engine is presented. The fuel spray is divided into small packages and the effect of air velocity pattern on spray development is taken into account. The calculation of swirl intensity variations during the cycle is based on hybrid solid body-boundary layer rotation scheme. Application of the mass, energy and state equations in each zone yields local temperatures and cylinder pressure histories. For calculating the concentration of constituents in the exhaust gases, a chemical equilibrium scheme is adopted for the C-H-O system of the eleven species considered, together with chemical rate equations for the calculation of nitric oxide (NO). A model for the evaluation of soot formation and oxidation rates is incorporated. A comparison is made between the theoretical results from the computer program implementing the analysis, with experimental results from a vast experimental investigation conducted on a direct injection, Lister-Petter diesel engine, with very encouraging results. Plots of temperature, equivalence ratio, NO and soot distributions inside the combustion chamber are presented, elucidating the physical mechanisms governing combustion and pollutants formation.