Showing papers on "Diesel engine published in 1990"

Second-law analysis of diesel engine combustion

Abstract: A second-law analysis of the combustion process in a diesel engine is presented for a single-zone model. Expressions for availability and the availability balance are developed in detail from the energy and entropy balances and applied in a manner that allows the irreversibility due to combustion to be separated from that associated with heat transfer to the walls. Availability is divided into two components: thermomechanical and chemical availability. For the first time, chemical availability of the cylinder contents is dealt with rigorously, which allows for a correct determination of combustion irreversibilities. The analysis is applied in a parametric study of the effects of combustion timing, mass burning rate, and heat transfer rate on the irreversibility and system availability.

Effects of fuel aromatics, cetane number, and cetane improver on emissions from a 1991 prototype heavy-duty diesel engine

Abstract: Several diesel identified as having significant effects on diesel engine emissions. This paper reports, for heavy-duty diesel engines, fuel properties of aromatics, back end volatility (represented by the 90 percent boiling point), and sulfur examined in a previous CRC VE-1 study in which reductions in all three properties decreased regulated emissions to varying degrees. Aromatic levels and cetane numbers were generally correlated in the previous study, so variation in emissions due to aromatics could not clearly be assigned to variation in aromatic levels alone. To separate the effects of aromatics and cetane number, a fuel set with controlled variation in aromatics and cetane number was developed, including the use of ignition improver to increase the cetane number of selected fuels. The fuel set was used in a 1991 Prototype DDC Series 60 heavy-duty diesel engine to examine regulated emissions over EPA transient cycle operation. Results indicate that cetane number was the key fuel property affecting transient HC and CO emissions. In addition, cetane number was the principal fuel property affecting composite particulate emissions, but aromatic effects were also significant. For emissions of NO{sub x} both cetane number and aromatics were significant for transient emissions.

Diesel engine exhaust filtration system and method

Abstract: A diesel engine exhaust filtration system and method which removes both diesel particulate matter (DPM) and unburned hydrocarbons (UHC) from the exhaust gases Two filters in parallel are used, each alternating operation as the other regenerates Each filter is preferred to be constructed in a conventional manner and operates at between 100 to 300 degrees Centigrade A microprocessor controlled valve system regulates which filter is active and which is regenerating and/or inactive DPM accumulates at the active filter, with UHC condensing on the DPM When the active filter becomes clogged, the microprocessor switches it to inactive status, and switches the other filter to active status Low temperature regeneration is initiated by the microprocessor in which DPM and UHC burn slowly across the entire filter A recirculation conduit provides for the gases produced by the regeneration to be directed to the air intake of the diesel engine Any remaining UHC or DPM will be subsequently burned in the combustion chambers of the diesel engine or taken out by the other active filter When regeneration has completed, the inactive filter will await being switched by the microprocessor to active status when the other filter has become sufficiently clogged that it is time for it to be regenerated

Thermodynamic analysis of indirect injection diesel engines by two-zone modeling of combustion

Abstract: This work presents a thermodynamic analysis of a naturally aspirated, four-stroke, diesel engine with a swirl prechamber, under firing conditions during the open and closed part of the cycle. For calculating the heat exchange between gas and walls in both the main chamber and (swirl) prechamber, the relevant characteristic velocities and lengths are calculated by setting up a zero-dimensional energy cascade turbulence model. One-dimensional, quasi-steady, compressible flow with heat transfer inside the throat passageway connecting the two chambers is used. Combustion in both the main chamber and the swirl prechamber is attacked by proposing a two-zone combustion model, and following the movement of the spray plume inside an air solid body rotation environment in the prechamber and its later progression into the main chamber through the connecting throat. To validate the analysis, an extensive experimental investigation is undertaken at the laboratory of the authors on a flexible Ricardo, single-cylinder, swirl chamber diesel engine, and evaluating its performance in a wide range of operating conditions. The experimental results are found to be in good agreement with the theoretical results obtained from the computer program implementing the analysis.

Catalyst for purification of exhaust gas from diesel engine

Abstract: A novel catalyst for use in purification of exhaust gases from diesel engines is disclosed. This catalyst is a flow-through type honeycomb catalyst having parallel through cells and characterized in that (1) its cross-sectional area at the inlet part of an exhaust gas cut by a face vertical to the direction of the through cells is 10 to 100 cm, preferably 20 to 80 cm per liter of the displacement of the engine, (2) the hydraulic diameter of the through cells is 1.00 to 2.00 mm, preferably 1.10 to 1.40 mm, and (3) percentage of open frontal area at the inlet part of the exhaust gas is 40 to 95 % preferably 50 to 85 %. This catalyst can be one wherein a catalytically active component itself is extruded into a honeycomb shape or one wherein a catalytically active component is deposited on a honeycomb carrier.

Method of removing nitrogen oxides in exhaust gases from a diesel engine

Abstract: The present invention concerns a method of removing nitrogen oxides in exhaust gasses from a diesel engine (1) by using a catalyst in a reactor (10) under the presence of ammonia, wherein a humidity of intake air as a specific factor and one or more of engine power, fuel consumption amount of engine, temperature of engine intake air and exhaust gas temperature as selective factors are measured respectively as the measuring factors and the flow rate of ammonia is controlled based on measured values and ammonia is supplied to an exhaust gas flow channel (11) from the engine (1) to the reactor (10).

Regenerable exhaust gas filter element for diesel engines

Abstract: A regenerable exhaust gas filter element for diesel engines includes an interlaced network of mullite crystals grown together forming a rigid porous body. Soot carried by exhaust gas from a diesel engine flowing through the filter is trapped in the porous body and thereafter burned off to regenerate the element. A network of mullite crystals in accordance with the invention is automatically interlaced and fused with one another to form the porous body of the filter element.

Control system for diesel particulate trap regeneration system

Abstract: A control system for regenerating a particulate trap in the exhaust system of a diesel engine includes control logic which controls the air/fuel ratio of the engine by operating a backpressure valve in the engine exhaust system to provide a proper amount of excess oxygen to permit efficient combustion of the particulate content of the trap, but to avoid rapid and damaging combustion rates. Actual engine air/fuel ratio is compared to a commanded air/fuel ratio, and the position of the backpressure valve is adjusted accordingly. The commanded air/fuel ratio is ratcheted upwardly or downwardly once in a predetermined time period in response to a temperature error signal between exhaust gas temperature sensed in the engine exhaust manifold and a predetermined commanded temperature. An override is provided to permit the vehicle operator to override regeneration when power is required from the engine, and a low power cut-off is provided to suspend regeneration when the engine is operated for a period of time at low power conditions where regeneration is inefficient.

Diesel fuel aromatic and cetane number effects on combustion and emissions from a prototype 1991 diesel engine

Abstract: This book reports on a prototype 1991-model diesel engine that was tested using EPA transient emissions procedures to determine the effect of fuel properties on combustion characteristics and exhaust emissions. The eleven test fuel set focused primarily on total aromatic content, multi-ring aromatic content, and cetane number, but other fuel variables were also studied. Hydrotreating was used to obtain reductions in fuel sulfur and aromatic content. Increasing cetane number and reducing aromatic content resulted in lower emissions of hydrocarbons and NO{sub x}. Particulate emission were best predicted by sulfur content, aromatic content and 90% distillation temperature. Multi-ring aromatics showed a greater significance that total aromatics on hydrocarbon and particulate emissions. combustion parameters were highly dependent on fuel cetane number.

System for purifying the exhaust gases of diesel engines

Abstract: A system for purifying the exhaust gases of a diesel engine comprises an exhaust gas line, which is branched to form two branch lines, which are adapted to be shut off in alternation by change-over valve means. One of said branch lines constitutes a filter line, which incorporates a soot filter. The other branch line constitutes a by-pass line. Downstream of the soot filter the filter line joins the by-pass line to form a common end line. In dependence on the load on the engine, the filter line is opened by the change-over valve means only during an operation of the engine under a full load or under a partial load in excess of a predetermined value. In order to ensure that the exhaust gas will almost entirely be purified during an operation of the engine throughout its load range, an diesel soot oxidation-inducing catalyst is provided downstream of the change-over valve means and is incorporated in the by-pass line or in the common end line.

Variable geometry catalytic converter

Abstract: A system is provided for reducing detectable hydrocarbons in the exhaust gas of a diesel engine and for retarding the formation of sulfate including a housing having an inlet and an outlet, a first exhaust gas glow passage extending from the inlet to the outlet within the housing, a first catalyst bed positioned within the first flow passage, a second exhaust gas flow passage extending from the inlet to the outlet within the housing, and a second catalyst bed positioned within the second flow passage. Also provided is a valve for directing the flow of the exhaust gas through one of the first and second flow passages, and an electronic control for controlling the valve in response to engine load and exhaust gas temperature such that the exhaust gas is directed through the first flow passage and the first catalyst bed under low engine load and low exhaust gas temperature conditions and through the second flow passage and the second catalyst bed under high engine load and high exhaust gas temperature conditions.

Droplet Sizes and Velocities in a Transient Diesel Fuel Spray

Abstract: : Simultaneous droplet sizes and velocities were obtained for a transient diesel fuel spray in a quiescent chamber at atmospheric temperature and pressure. Instantaneous injection pressure, needle lift, and rate of injection were also measured, allowing calculation of the instantaneous nozzle discharge coefficient. Short-exposure still photographs were obtained at various chamber pressure and densities to further investigate this spray. Correlations between droplet size and velocity were determined at each crank angle to observe the detailed nature of the transient events occurring in this transient diesel fuel spray. As expected, peak mean and rms velocities are observed in the center of the spray. Measured average velocities are consistent with a calculated value, using the discharge coefficient for the nozzle and the known rate of fuel injection. The spray was nearly symmetric, with higher velocities occurring near the injector tip, and the radial dependence of velocity consistent with that observed from the spray photographs. Factors observed to effect the droplet size and velocity distributions and history include pump speed, fuel quantity delivered, and needle lift. Reprints. (aw)

Reduction of exhaust pollution of diesel engine - by fitting particle filter and oxidising catalyser

Abstract: The diesel engine has a superchanger (7) which is driven by an exhaust gas turbine (4). The turbine (4) is fitted in the exhaust pipe (5, 6) which is fitted with a particle filter (2). The supercharger is fitted in the combustion air pipe (8, 9). In the upstream direction from the exhaust gas turbine there is an oxidising catalyser (12) and behind this, the particle filter is mounted. An exhaust gas cooler (10) is mounted in the pipe (3) which connects the particle filter to the compressor inlet pipe (9). USE - Diesel engines.

Two cycle diesel engine

Abstract: A diesel engine operating on the two cycle crankcase compression principle and having a means for reducing nitrous oxide emissions under low and medium range speeds. This is done by throttling the scavenge air flow which can be accomplished either by throttling the air admitted to the crankcase chamber or bypassing a portion of the compressed air from the crankcase chamber back to the induction system. In addition, an exhaust control valve is provided for raising the compression ratio and the injection timing is advanced when the scavenge air is reduced so as to further improve the control of hydrocarbon and carbon monoxide emissions.

Method and device for the automatic introduction of an additive into the fuel tank of a motor vehicle, and their use in the case of a vehicle with a diesel engine

Abstract: The initial level of fuel in the tank (2) is measured prior to each operation of refilling the tank (2) with fuel. The final level of fuel in the tank (2) is measured at the end of each of the refilling operations. The quanity of fuel introduced into the tank (2) during each of the refilling operations is determined, and the amount of additive necessary to maintain the concentration of additive in the fuel at a fixed predetermined value is determined. The previously determined amount of additive is automatically injected into the tank. The invention applies particularly to the introduction into a diesel fuel tank (2), of an additive making it possible to lower the ignition tempreature of the soot in a particle filter of a motor vehicle with a diesel engine.

Flattened profile diesel engine exhaust oxidizer

Abstract: A flattened profile emission oxidizing device for removing soot and other particulates from the exhaust gases of a diesel engine having an enclosure with a forward inlet for receiving diesel engine exhaust, a main flow path through the enclosure, a bypass through the enclosure for diverting flow from the main flow path, and a control means for selectively controlling the flow through the main flow path and the bypass in accordance with certain sensed conditons relating to the status of engine operation and the condition of a particulate trapping medium that is disposed in the main flow path. The main flow path has an electrostatic precipitator that is disposed in underlying relationship to the particulate trapping medium in the main flow path and a series of vanes are disposed in underlying relationship to the electrostatic precipitator and serve to redirect the exhaust flow passing through the main flow path and distribute the exhaust flow over the electrostatic precipitator and the trapping medium. A thermal stabilizer in the outlet of the device attenuates the peak temperatures of the exhaust gases.

Method of and an apparatus for regenerating a diesel particulate exhaust filter

Abstract: A method of and an apparatus for regenerating a diesel filter (1) mounted in the exhaust pipe (3) of a diesel engine (2) wherein for initiating regeneration, the exhaust flow is throttled in the exhaust pipe (3) and/or in an exhaust feedback passage (7) by means of a control unit (10) responsive to setpoint exhaust temperatures measured upstream and downstream of the diesel filter (1) in the exhaust pipe (3), and that the air ratio is set to a value between 1.2 and 1.3 to inhibit regeneration.

Velocity and Drop Size Measurements in Fuel Sprays in a direct injection diesel engine

Abstract: High-pressure injection fuel sprays have been investigated in a single-cylinder research Diesel engine using the laser and phase Doppler anemometry techniques to measure fuel droplet velocities and sizes and their spatial and temporal distributions within the spray. The measurements relate to the determination of the droplets' axial velocity component and diameter on the spray centre line between 75 and 100 nozzle diameters downstream from a single-hole injector nozzle. The experimental program covered the use of both Diesel and a non-combusting alcohol fuel. Measurements at radial locations in the spray and at different fuel loads were also taken for the alcohol fuel. Temporally resolved measurements of droplet velocity and size are presented together with time — averaged values in such a way as to isolate the contributions from the leading and trailing regions of each spray and identify two different break — up mechanisms occurring as suggested by a conceptual model of the spray behaviour.

In-cylinder control of particulates and nitric oxide for diesel engine

Abstract: A method using concurrently and simultaneously certain control factors for in-cylinder combustion, at least two of such factors being at levels never tried before by the prior art The combination of control factors comprises: (i) high pressure charging of supply air for enhanced excess oxygen; (ii) advanced techniques for improved in-cylinder mixing of fuel and air (ie, high swirl, reentraining piston bowl configuration, high compression ratio); (iii) high pressure injection of diesel fuel at levels of 11 X 10⁵ - 15 X 10⁵ kPa (16-­22 x 10³ psi); (iv) smaller fuel nozzle ports for creating finer droplet size; (v) retardation of fuel injection from TDC by 2-5/; and (vi) limitation of the ingress of lubricating oil into the combustion chamber by use of noncompressed cylinder sleeves to enhance piston to bore concentricity and preferably by other augmenting limits

Engine exhaust system with sequential loading of multiple filters

Abstract: In a diesel engine exhaust system a plurality of valved ceramic filters are connected in parallel in the exhaust stream and loaded sequentially. While one filter is preferentially loaded, a second filter is opened to the exhaust stream when backpressure reaches a predetermined value. The secondary filter is removed from the exhaust stream when air flow to the engine drops a discrete amount below a peak air flow determined by the backpressure which would cause the secondary filter to be placed in the exhaust stream. The preferentially loaded filter is bypassed when completely loaded and regenerated. The secondary filter is then preferentially loaded and the sequence continues.