Showing papers on "Lean burn published in 2000"

Critical review of nitrogen monoxide sensors for exhaust gases of lean burn engines

Abstract: The paper intends to establish a comprehensive state of the art of nitrogen monoxide sensors applicable to the exhaust gas of lean-burn engines. The drastic operating conditions imply similar requirements to the oxygen lambda gauge. To date, like for oxygen sensing, only solid electrolyte- and semiconductor oxide-based sensors can be considered for NO sensing. The results of an exhaustive literature search on these types of sensors permit to propose some directions of research, taking into account principles, materials and manufacturing technologies.

Innovative Ultra-low NOx Controlled Auto-Ignition Combustion Process for Gasoline Engines: the 4-SPACE Project

Abstract: The purpose of the 4-SPACE (4-Stroke Powered gasoline Auto-ignition Controlled combustion Engine) industrial research project is to research and develop an innovative controlled auto-ignition combustion process for lean burn automotive gasoline 4-stroke engines application. The engine concepts to be developed could have the potential to replace the existing stoichiometric / 3-way catalyst automotive spark ignition 4-stroke engines by offering the potential to meet the most stringent EURO 4 emissions limits in the year 2005 without requiring DeNOx catalyst technology. A reduction of fuel consumption and therefore of corresponding CO2 emissions of 15 to 20% in average urban conditions of use, is expected for the « 4-SPACE » lean burn 4-stroke engine with additional reduction of CO emissions. This paper describes the first set of results of different experimental and numerical studies aiming to get such new combustion process in 4-stroke engines within the framework of this European consortium. One of the target of this consortium driven by IFP, is to develop a 4-stroke gasoline engine running conventionally at high load (with a normal compression ratio and without any intake air heating) and able to achieve Controlled Auto-Ignition (CAI) process at part load by reproducing the 2-stroke internal conditions (internal EGR rate and fluid dynamic control, temperature level...) favorable to this particular combustion process. For this purpose and as a starting point of the work program, a production 2-stroke engine known for its part load auto-ignition behavior is fully studied. Such work is focused on the analysis of in-cylinder conditions prior to auto-ignition using combined experimental testing, 3D CFD computations and optical diagnostics. From this analysis, 1D CFD computations have been extensively performed to evaluate the possible 4-stroke concepts able to reproduce internal conditions favorable to CAI. Then, the most “promising” configurations have been experimentally investigated. Encouraging preliminary results have already shown that NOx emissions are reduced by 10 to 40 times and the fuel economy is improved by 8 to 10% when compared with stoichiometric reference conditions. Other ways of getting auto-ignition of the lean fresh mixture are also explored by the project partners. The effects of several parameters, such as the fuel composition, the engine compression ratio, the intake air temperature level, etc... are also included in the research program. Thus, to analyze better analyze intrinsic autoignition process, specific tools as for example Rapid Compression Machine have been developed. Different fuels at various initial conditions (e.g. temperature, excess air) have been tested and compared, for example in terms for example of combustion rate and auto-ignition delay. Results obtained contribute to the better understanding of the auto-ignition process. Preliminary visualization results from specially designed single cylinder engines (2-stroke and 4-stroke) have been obtained for controlled auto-ignition combustion. The effect of charge stratification is briefly discussed.

Exhaust gas purification system for a lean burn engine

Abstract: An exhaust gas purification system for an engine equipped with a turbocharger (20) and an exhaust pipe having a NO x conversion catalyst (40) therein. The system comprises a reservoir (30) for storing pressurised air received from the turbocharger, a reductant injector (42) in fluid communication with a reductant supply (44), and a mixing chamber (36) in fluid communication with the reservoir (30) and connected to the reductant injector (42). The reductant injector (42) is responsive to an injection signal for atomising and injecting a quantity of reductant into the mixing chamber (36). The mixing chamber (36) is in fluid communication with the exhaust pipe for introducing a quantity of air and reductant mixture into the exhaust gas flow upstream of the NO x conversion catalyst (40).

Plasma fuel processing for NOx control lean burn engines

Abstract: A highly reactive reducing gas mixture is produced from vehicle fuel and introduced into the exhaust gas of an internal combustion engine operated at lean burn conditions and passed over a reducing catalyst to convert NOX emissions to benign emissions. Preferably, fuel with oxygen present in a carrier gas is metered into a plasma reactor having a bed of dielectric particles which prevent formation of coke as the fuel is reacted. The plasma induces a number of simultaneous reactions with the fuel to produce a substantial amount of oxygenated and non-oxygenated, unbranched organic molecules at relatively low temperatures that are highly reactive and ideally suited for use as a reducing agent in an SCR catalyst.

Dual-bed catalytic system for NOx–N2O removal: a practical application for lean-burn deNOx HC-SCR

Abstract: A dual-bed catalytic system has been developed by which NOx and N2O are successively removed from flue gases, simulating lean-burn engine conditions. NOx is removed in the first stage by selective catalytic reduction with propene over a Pt supported on activated carbon catalyst. The second bed decomposes the N2O formed in the first bed into N2 and O2. Catalysts tested in this second stage comprise ex-Co-Rh,Al-HTlc and ex-Co,Pd-La,Al-HTlc mixed oxides derived from hydrotalcite-like compounds and ion-exchanged Fe-ZSM-5 and Pd-ZSM-5 zeolites. Variables studied for the most promising deN2O catalysts are the effect of the pretreatment, the sodium content of the ex-HTlc-catalysts, the presence of inhibitors in the feed stream, the addition of hydrocarbons to enhance the N2O reduction in the second bed, and both time-on-stream and thermal stability of the catalytic system. Ex-Co-Rh,Al-HTlc proved to be the most active and stable catalyst, followed by Fe-ZSM-5, even when propene was added as reducing agent, which enhanced the conversion over the latter catalyst only. In an optimal configuration, at a temperature of 475 and 700 K in the first and second stage, respectively, molar conversions of 90 and 100% for NOx and N2O were achieved in a stable operation during 50 h.

Torque control strategy for engines with continuously variable transmission

Abstract: A method and system for controlling torque disturbances in direct injection stratified charge and lean burn port-fuel injection engines ( 12 ) through continuously variable transmission ( 40 ). The method and system include using the continuously variable transmission ( 40 ) to mitigate the effects of torque disturbances due to a lean NO x trap ( 22 ) purge cycle ( 100 ). The continuously variable transmission ( 40 ) is coordinated with other engine variables, such as throttle ( 36 ), fueling rate (W f ), injection timing (γ), and spark timing (δ), to keep the operation near the optimal regime. In periods of trap ( 22 ) purge, the engine control variables and the continuously variable transmission ( 40 ) are coordinated to maximize purge efficiency for a predetermined period of time. In periods of normal operation ( 102 ), the engine control variables and the continuously variable transmission ( 40 ) are coordinated to minimize fuel consumption subject to emission constraints.

Control of exhaust temperature in lean burn engines

Abstract: A method (100) and system for actively controlling the temperature of engine (10) exhaust gas entering an aftertreatment device and thereby controlling undesirable emissions. Through control of the turbine blade position of a variable geometry turbocharger (16), the temperature of the exhaust gas entering the aftertreatment device is maintained within the operating temperature window for the device, and at the same time, achieves the fuel economy benefits associated with turbocharging.

System and method of controlling air-charge in direct injection lean-burn engines

Abstract: A method and system for controlling the air charge in a direct injection spark ignition engine that provides proportional plus integral control in positioning an electronic throttle control valve and an exhaust gas recirculating valve in order to compensate for uncertainties in the EGR valve flow area. An adaptation algorithm is used to improve the estimate of in-cylinder flow and throttle open-loop control.

Variable premix-lean burn combustor

Abstract: A method and device are provided to enable optimizing combustion conditions of a continuous combustion device to produce low emissions of nitric oxide, carbon monoxide and hydrocarbons at all operative conditions. The continuous combustion device includes a slidable baffle (50) to regulate, according to power levels, not only an airflow directly into a primary combustion zone (28) and a secondary combustion zone (30) but also an airflow into a fuel/air premix device (20) to maintain the fuel/air ratio in the primary combustion zone optimized both at an average level and in local areas. Such that, low objectionable or harmful emissions can be reached without performance penalties of the combustion device, such as anti-ignition, flashback or flameout.

Stable pre-mixer for lean burn composition

Abstract: A combustion system includes a combustion chamber and a fuel injection apparatus, where a radial inflow swirler stage in the injector housing includes a plurality of radial inflow swirlers spaced longitudinally from each other to direct air radially inward in a swirling motion to cause fuel streams to swirl and thoroughly mix with air before passing into the combustion chamber. A plurality of liquid fuel nozzles are supported in the housing in an annular arrangement to dispense liquid fuel in a plurality of sprays in the downstream direction. A plurality of gaseous fuel nozzles are also provided in the housing supported in an annular arrangement intermediate the liquid fuel nozzles. The plurality of gaseous fuel nozzles include a series of nozzles arranged in radial spokes between each of the liquid fuel nozzles, with the size of the openings in the gaseous fuel nozzles increasing in the radially outer direction from the longitudinal axis of the housing. An outer annular flow passage is provided around the nozzles to create a cylindrical sheet of air around all the fuel streams, while an annular flow passage is provided around each of the liquid fuel nozzles to provide an annular flow of air around each of the liquid fuel sprays. A central air passage provides air centrally of the arrangement of nozzles. The air vaporizes the liquid fuel as the fuel passes downstream through the housing.

Exhaust catalyst system includes three-way catalyst removing reductants carbon monoxide and hydrocarbons, followed by two nitrogen oxide storage catalysts optimized for operation at different temperatures

Abstract: A catalyst system (10) in an exhaust line includes successive nitrogen oxide (NOx) storage catalysts (18, 20). An Independent claim is also included for a method of purifying exhaust gas, using the above system. NOx from lean burn operation is absorbed in the first and/or second NOx storage catalyst(s). After exceeding an NOx desorption temperature at the first catalyst, and an NOx desorption temperature at the second catalyst, or after exceeding a storage volume for NOx at the first catalyst and/or a storage volume for NOx at the second catalyst, the engine is operated in a rich mode.

Catalysts for lean burn engine exhaust abatement

Abstract: The present invention provides a process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material by contacting the gas stream under conditions effective to catalytically reduce the nitrogen oxides with a catalyst comprising a aluminum-silicate type material and a minor amount of a metal, the catalyst characterized as having sufficient catalytic activity so as to reduce the nitrogen oxides by at least 60 percent under temperatures within the range of from about 200° C. to about 400° C.

Torque control scheme for low emission lean burn vehicle

Abstract: A method of minimizing torque disturbances in an internal combustion engine for a vehicle having a lean NOx trap that is periodically purged. The method includes the steps of generating feedforward values of first engine characteristics as a function of desired engine torque and generating feedback values of second engine characteristics as a function of intake manifold pressure. Target values are then calculated for predetermined engine variables based on the first and second engine characteristics. Engine variables are then set to the target values to compensate for torque disturbances resulting from the lean NOx trap purge cycle. According to the disclosed method, the feedforward path schedules the throttle, fuel rate and spark timing based on an engine model to produce a demanded engine torque. The feedback path then uses the values of fuel rate and spark timing to compensate for torque variations. This is accomplished by determining an error term as a function of a reference trajectory intake manifold pressure and measured intake manifold pressure.

Online identification and adaptation of LNT models for improved emission control in lean burn automotive engines

Abstract: In the absence of online emission measurements, the control of lean burn engine after treatment system is often done in a feedforward fashion based on models of feed gas emissions and the after-treatment subsystems. When the ambient conditions (such as humidity) change or the engine components age, these models are no longer accurate, and the performance of the control system that relies on these models may deteriorate. In this paper, we show how the parameters of a lean NOx trap (LNT) model can be identified online using a conventional switching exhaust gas oxygen sensor to improve robustness of the after treatment control system.

NH3 generation catalysts for lean-burn and diesel applications

Abstract: A catalyst for converting NO x in exhaust gases from internal combustion engines to NH 3 includes a perovskite material or a metal oxide impregnated with a noble metal, the metal oxide comprising at least one selected from Fe 2 O 3 , Cr 2 O 3 , MgO, La 2 O 3 , and CeO 2 , and the noble metal comprising at least one selected from Pt, Pd, Ir, Rh, and Ru.

Method and apparatus for controlling lean-burn engine based upon predicted performance impact and trap efficiency

Abstract: A method and apparatus for controlling the operation of a “lean-burn” internal combustion engine in cooperation with an exhaust gas purification system having an emissions control device capable of alternatively storing and releasing NO x when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, determines a performance impact, such as a fuel-economy benefit, of operating the engine at a selected lean operating condition, with due consideration of the periodic rich operating condition necessary to release stored NO x from the device. The method and apparatus further determine a measure representative of the instantaneous NO x -storing efficiency of the device. The method and apparatus enable the selected lean operating condition as long as the determined performance impact and the determined device efficiency are each above respective predetermined minimum levels.

Exhaust Oxidation of Unburned Hydrocarbons from Lean-Burn Natural Gas Engines

Abstract: Post cylinder oxidation of unburned hydrocarbons (UHC) was studied using a 35 kW lest engine. The engine was equipped with an insulated exhaust reactor to extend the residence time. The exhaust reactor performance has been characterised under the basic engine operating conditions, and under conditions where temperature and composition (NOx level) of the exhaust were modified independent of engine settings. The experiments studied spanned a wide range of moderately lean-bum conditions. The composition at the exhaust port was as follows: O2 5-9% (engine excess air ratios of 1.28-1.75), UHC 1000-7000 ppm, CO 550 ppm, NOx0-1400 ppm. The temperature varied from 600 to 700°C, In addition, experiments with injection of hydrogen peroxide to promote UHC oxidation in the exhaust system were conducted. The amount of UHC oxidised in the exhaust system depended closely on the exhaust temperature, residence time and concentration of nitrogen oxides in the exhaust gas. The increased reaction time in the exhaust...

Ignition limit of lean mixture by hydrogen flame jet ignition

Abstract: A hydrogen flame jet ignition method is proposed to achieve the secure ignition and stable combustion of an ultra lean mixture The mechanism of enhancement by the jet ignition method, especially the role of radicals in the flame jet, is analyzed first and the lean limit of ignition is investigated by the hydrogen flame jet ignition method This proved that the effect of radicals on the enhancement of lean mixture combustion is smaller than the turbulent effect The lean limit of stable ignition at atmospheric pressure is therefore almost the same as that of the inflammability limit, namely around φ =05 When gas temperature and pressure are increased to actual engine conditions, the lean limit is widened to around 03 which is much lower than conventional lean burn engine conditions

Apparatus for purifying and controlling exhaust gases

Abstract: An apparatus for purifying and controlling exhaust gases having NO x adsorption catalyst in the exhaust gas duct therein, and conducting exhaust gas purification by adsorbing or capturing NO x in the oxidative atmosphere of lean exhaust gas, producing a reductive atmosphere and regenerating the adsorption catalyst, characterized by carrying out a reduction treatment of NO x on the basis of a calculated quantity of adsorbed NO x , said calculated quantity of adsorbed NO x being obtained by subtracting the quantity of NO x directly reduced to N 2 from the total NO x in exhaust gas, can maintain the NO x purification rate in the lean burn exhaust gas of internal combustion engine always at a prescribed level or above and thereby lowering the quantity of discharged harmful exhaust gas.

Industrial RB211 DLE Gas Turbine Combustion Update

Abstract: Industrial gas turbines have universally had problems with combustion amplified pressure oscillations (combustion instability or noise) in premix lean burn combustors. Reference 1 issued by General Electric is a particularly good report. Under specific conditions a resonant frequency achieves sufficient amplitude to cause severe damage to the combustor. As the emissions are reduced to lower levels, by achieving better uniformity of fuel and air distribution and a larger percentage of the air is used in the combustion process, then these amplitudes have the potential to become greater especially at high pressure ratios. Small changes in either ambient conditions or fuel quality appear to cause noise amplitudes to become unacceptable.Copyright © 2000 by ASME

Speciated hydrocarbon emissions from a gas-fuelled spark-ignition engine with various operating parameters

Abstract: For natural gas and liquefied petroleum gas (LPG), measurements of the concentrations of individual exhaust hydrocarbon (HC) species have been made under various engine operating conditions in a 2 litre four-cylinder engine using gas chromatography. Non-methane hydrocarbon (NMHC) in addition to the species of HC and other emissions such as CO2, CO and NOx were examined for natural gas and LPG at 1800 r/min for two compression ratios (8.6 and 10.6), various brake mean effective pressure (b.m.e.p.) values (250-800 kPa), spark timings (before top dead centre 10°-55°) and exhaust gas recirculation ratios up to 7 per cent. Fuel conversion efficiencies were also investigated together with emissions to study the effect of engine parameters on the combustion performance in gas engines, especially under the lean burn conditions.It was found that CO2 emission decreased with smaller C value of fuel, leaner mixture strength, higher compression ratio, higher b.m.e.p. and the ignition near the maximum brake tor...

Effect of Simulated Diesel Exhaust Gas Composition and Temperature on NOx Reduction Behavior of Alumina and Zeolite Catalysts in Combination With Non-Thermal Plasma

Abstract: NOx reduction under simulated lean burn conditions was studied using a non-thermal plasma in combination with zeolite and alumina catalysts The influence of temperature and plasma treatment on the catalytic performance was investigated Zeolite catalyst B showed high activity in the 150-300 degree Celcius temperature region Alumina Catalyst D was most active at temperatures higher than 250 degrees Celcius In addition, the alumina catalyst was effective in oxidation of aldehydes formed during plasma treatment of the reaction mixture When the reaction was carried out over a catalyst bed consisting of separate layers of the zeolite and alumina catalyst, the catalyst temperature range for significant NOx reduction was expanded to 150-500 degrees Celcius

Method of regenerating an activated-carbon canister

Abstract: The fill level of an activated-carbon canister is calculated during the regeneration process in a lean burn combustion engine. While the engine is in idle operation, the fuel mass reduction that is adjusted by a momentum-based idle controller is used as a measure of the hydrocarbon mass flow that is delivered in the regeneration process, when the activating-carbon filter is flushed back into the engine via its intake tract.

Exhaust gas purifying device for lean-burn IC engine comprises a nitrogen oxides storage catalyst and a pre-catalyst

Abstract: The exhaust gas purifying device for a lean-burn IC engine (10) comprises a nitrogen oxides storage catalyst (14) and a pre-catalyst (12). The pre-catalyst volume is less than 40% of the piston capacity of the IC engine.

Combined plasma reactor catalyst systems for effective emission control over a range of operating conditions

Abstract: An apparatus and method for removing pollutant from exhaust gas of a lean burn engine (11). The apparatus has at least one device (13) for removing oxides of nitrogen, hydrocarbons, carbon monoxide, and particulates in the exhaust gas. The device (13) is selected from the group consisting of selective catalytic reduction catalysts, particulate traps, and three-way catalysts, and is positioned, such that at least a portion of the exhaust gas stream (18) from the lean burn engine (11) passes through the device (13); and at least one a device (14, 30, 40, 50, 60, 80) for producing a non-thermal plasma in at least a portion of the exhaust gas stream (18). A portion of the exhaust gas stream (18) is exposed to the non-thermal plasma (14, 30, 40, 50, 60, 80), and introduced into the exhaust gas stream (18) at a point upstream of the catalytic converter (13) for removing at least one of oxides of nitrogen, hydrocarbons, carbon monoxide, and particulates.

Exhaust emissions control apparatus for internal combustion engine has NOx reduction-absorption catalyst and selective reduction catalyst kept operational by adding ammonia

Abstract: Emissions control apparatus has a first NOx reduction/absorption catalyst in the exhaust duct of a lean burn internal combustion engine and a second selective reduction catalyst. The first catalyst absorbs NOx when the air-fuel ratio is leaner than a theoretical ratio and releases NOx when oxygen in the exhaust gas reduces. An ammonia compound is added to the second catalyst to maintain the selective reduction. Emissions control apparatus has a first NOx reduction/absorption catalyst in the exhaust duct of a lean burn internal combustion engine and a second selective reduction catalyst. The first catalyst absorbs NOx when the air-fuel ratio is leaner than a theoretical ratio and releases NOx when oxygen in the exhaust gas reduces. An ammonia compound is added to the second catalyst to maintain the selective reduction. The catalysts may be in parallel or in series with the first catalyst preferably upstream. A valve may enable selective by-passing of the first catalyst when arranged in series. A third catalyst may be upstream of both catalysts. The amount of ammonia compound depends upon the NOx concentration and/or temperature of the exhaust gas.

Catalytic converter, diesel engine and lean-burn engine having a catalytic converter

Abstract: A catalytic converter for cleaning exhaust gas from an internal combustion engine, in particular a diesel engine or a lean-burn engine, includes at least one honeycomb body coated with catalytically active material and having passages through which the exhaust gas can flow, walls separating the passages from each other, and first and second zones disposed in succession in a flow direction. The first zone has a lower thermal capacity per unit of volume of the honeycomb body than the second zone and the second zone has a thermal capacity of at least 800 joules per liter and Kelvin [J/lK], preferably at least 900. Sheet metal layers in the first zone preferably have an average uncoated thickness of less than 0.06 mm, preferably less than 0.04 mm. Sheet metal layers in the second zone preferably have an average uncoated thickness of more than 0.06 mm, preferably more than 0.08 mm and in particular 0.11 mm. In that way, the first zone can rapidly reach its operating temperature at high exhaust gas temperatures while the second zone stores heat for operating conditions involving a low exhaust gas temperature.