Showing papers on "Lean burn published in 2005"

Exhaust Gas Control Apparatus for Internal Combustion Engine

Abstract: A first cylinder and a second cylinder are provided. A first exhaust pipe is connected to the first cylinder and a second exhaust pipe is connected to the second cylinder. A communicating pipe connects together an intermediate portion of the first exhaust pipe with an intermediate portion of the second exhaust pipe. An exhaust gas control catalyst is arranged in the second exhaust pipe downstream of the portion to which the communicating pipe is connected. Exhaust gas amount reducing devices are provided which reduce the amount of exhaust gas that flows from the first exhaust pipe into the second exhaust pipe through the communicating pipe during execution of rich/lean burn control which performs combustion with an air-fuel ratio of an air-fuel mixture that is richer than the stoichiometric air-fuel ratio in one of the first cylinder and second cylinder and performs combustion with an air-fuel ratio of an air-fuel mixture that is leaner than the stoichiometric air-fuel ratio in the other cylinder.

Lean Burn Natural Gas Operation vs. Stoichiometric Operation with EGR and a Three Way Catalyst

Abstract: Exhaust emissions from lean burn natural gas engines may not always be as low as the potential permits, especially engines with open-loop lambda control. These engines can produce much higher emissions than a comparable diesel engine without exhaust gas aftertreatment. Even if the engine has closed-loop lambda control, emissions are often unacceptably high for future emission regulations. A three-way catalyst is, today, the best way to reduce hazardous emissions. The drawback is that the engine has to operate with a stoichiometric mixture and this leads to; higher heat losses, higher pumping work at low to medium loads, higher thermal stress on the engine and higher knock tendency (requiring lower compression ratio, and thus lower brake efficiency). One way to reduce these drawbacks is to dilute the stoichiometric mixture with EGR. This paper compares lean burn operation with operation at stoichiometric conditions diluted with EGR, and using a three-way catalyst. The results show that nitric oxides (NOdx) and hydrocarbon (HC) emissions are several orders of magnitude lower than at lean operation. Higher loads can be achieved, and brake efficiency is higher than lean operation optimized for low NOdx production. A fast burning (high turbulence) combustion chamber is used to allow high amounts of dilution. (Less)

Analysis of Periodic Storage and Reduction of NOx in Catalytic Monoliths

Abstract: A one-dimensional two-phase model of an adsorptive catalytic monolith reactor is developed and analyzed. The model simulates the generic features of NOx storage and reduction (NSR), a periodic process involving the sequential trapping on a storage component and conversion of NOx to nitrogen under lean conditions found in the exhaust of lean burn and diesel vehicles. The reactor model includes a phenomenological microkinetic model of NSR on a bifunctional storage catalyst. We examine the effects of several design and operating parameters on the reactant conversion, including cycle timing, feed flowrate, composition, and temperature. The simulations reveal complex spatio-temporal phenomena in the form of traveling concentration and temperature waves. The extent of site blocking by oxygen of NOx adsorption is an important determinant of cyclic enhancement of the NOx conversion. The model predictions are in qualitative agreement with experimental observations reported in the literature. For example, the NOx c...

Reducing agent metering system for reducing nox in lean burn internal combustion engines

Abstract: A reducing agent metering system (100) for delivering reducing agent to a lean burn internal combustion engine (212). The reducing agent metering system (100) includes a metering system housing (180), a system for metering vaporized reducing agent (50) to the internal combustion engine (212), the system positioned within the metering system housing (180) and a system for delivering an atomized stream of liquid reducing agent to the lean burn internal combustion engine (212), the system positioned within the metering system housing (180), wherein the reducing agent metering system (100) is operable to transition from metering vaporized reducing agent to delivering an atomized stream of liquid reducing agent to the lean burn internal combustion engine (212).

Combustion optimization in a hydrogen-enhanced lean burn SI engine

Abstract: As part of ongoing research on hydrogen-enhanced lean burn Sl engines, this paper details an experimental combustion system optimization program. Experiments focused on three key areas: the ignition system, in-cylinder charge motion produced by changes in the inlet ports, and uniformity of fuel-air mixture preparation. Hydrogen enhancement is obtained with a H 2 , CO, N 2 mixture produced by a fuel reformer such as the plasmatron. The ignition system tests compared a standard inductive coil scheme against high-energy discharge systems. Charge motion experiments focused on the impact of different flow and turbulence patterns generated within the cylinder by restrictor plates at the intake port entrance, as well as novel inlet flow modification cones. The in-cylinder fluid motion generated by each configuration was characterized using swirl and tumble flow benches. Mixture preparation tests compared a standard single-hole pintle port fuel injector against a fine atomizing 12-hole injector. Results indicate that optimizations of the combustion system in conjunction with hydrogen-enhancement can extend the relative air/fuel ratio A at the lean limit of operation by roughly 25% compared against the baseline configuration. Nearly half of this improvement may be attributed to improvements in the combustion system. Furthermore, hydrogen-enhancement produces a nearly constant lean misfire limit improvement of -0.20 - 0.25 A values, regardless of baseline combustion behavior. In contrast, the improvement of the amount of dilution with excess air at the point of peak engine efficiency decreases as engine operation becomes leaner, due to the inherently lengthening burn duration as λ increses.

Selective Catalytic Reduction of Nitrogen Oxides from Exhaust of Lean Burn Engine over In-Situ Synthesized Cu-ZSM-5/Cordierite

Abstract: ZSM-5 zeolite was in-situ synthesized successfully on the surface of honeycomb cordierite substrate, certified by XRD and SEM techniques. Good thermal and hydrothermal stability of ZSM-5/cordierite could be obtained because of the in-situ synthesis method. Copper ion-exchanged ZSM-5/cordierite was studied as catalyst for selective catalytic reduction of nitrogen oxides. For practical reasons, the catalytic testing experiments were preformed on a real lean burn engine. Unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductants for NOx reduction. Cu−ZSM-5/cordierite exhibited high catalytic activity, and at 673 K the maximal NOx conversion to N2 could reach 50% at gas hourly space velocity (GHSV) of about 25 000 h-1. Hydrocarbons and carbon monoxide in the exhaust could also be purified at the same time. As expected, Cu−ZSM-5/cordierite catalyst exhibited good duration and antipoison properties. When traces of lanthanum were introduced to Cu−ZSM-5/cordierite catalyst as a modi...

Rich-Catalytic Lean-Burn Combustion for Low-Single-Digit NOx Gas Turbines

Abstract: A new rich-catalytic lean-burn combustion concept (trademarked by PCI as RCL) was tested at industrial gas turbine conditions, in Solar Turbines' high-pressure (17 atm) combustion rig and in a modified Solar Turbines engine, demonstrating ultralow emissions of NO x <2 ppm and CO<10 ppm for natural gas fuel For the single-injector rig tests, an RCL catalytic reactor replaced a single swirler/injector NO x <3 ppm and CO<10 ppm were achieved over a 110°C operating range in flame temperature, including NO x < 1 ppm at about 1350°C flame temperature Combustion noise was less than 015% peak to peak Four RCL catalytic reactors were then installed in a modified (single can combustor) engine NO x emissions averaged 21 ppm over the allowable operating range for this modified engine, with CO<10 ppm and without combustion noise (less than 015% peak to peak)

A New Flame Jet Concept to Improve the Inflammation of Lean Burn Mixtures in SI Engines

Abstract: Engines with gasoline direct injection promise an increase in efficiency mainly due to the overall lean mixture and reduced pumping losses at part load. But the near stoichiometric combustion of the stratified mixture with high combustion temperature leads to high NO x emissions. The need for expensive lean NO x catalysts in combination with complex operation strategies may reduce the advantages in efficiency significantly. The Bowl-Prechamber-lgnition (BPI) concept with flame jet ignition was developed to ignite premixed lean mixtures in DISI engines. The mainly homogeneous lean mixture leads to low combustion temperatures and subsequently to low NO x emissions. By additional EGR a further reduction of the combustion temperature is achievable. The BPI concept is realized by a prechamber spark plug and a piston bowl. The main feature of the concept is its dual injection strategy. A preinjection in the inlet stroke leads to a homogeneous lean mixture with an air-fuel ratio of λ = 1.4 to λ = 1.7. During the compression stroke a second direct injection with a small amount of fuel (about 3 % of the total fuel mass) is directed towards the piston bowl. The enriched air fuel mixture in the piston bowl is transported by the piston motion towards the prechamber spark plug. Due to the pressure difference between main combustion chamber and prechamber the mixture is transported with a highly turbulent flow into the prechamber. After reliable ignition of the enriched mixture in the prechamber, flame jets penetrate into the main combustion chamber and ignite the lean mixture. Numerical and experimental investigations were carried out in a modified 3-valve single cylinder engine for part load operation. The in-cylinder flow including the mixture process in the main combustion chamber and in the prechamber was investigated by CFD simulation, so that the local mixture composition could be predicted. With extended test runs and measurements the functionality of the BPI concept has been proved. For the quantification of the mixture enrichment in the prechamber spark plug ion current measurement has been found as an appropriate measurement tool [11][12]. At part load operation in BPI mode significant reductions in fuel consumption and NOx emission have been achieved compared to stoichiometric operation. Further investigations at full load have been carried out on a single cylinder engine and a 4-cylinder production engine to analyse the influence of prechamber spark plugs on one hand and the influence of lean operation on the other hand on the engine process. Homogeneous full load operation with the prechamber spark plug has shown a reduction in knock sensitivity. Due to significantly reduced cyclic fluctuations the maximum knock amplitudes at the knock limit was reduced.

Estimation of oxygen concentration in the intake manifold of an unthrottled lean burn engine

Abstract: A method of estimating oxygen concentration in the intake of a lean burn engine is accomplished during throttled operation by repeatedly combining determined air/fuel ratio and intake mass air flow and estimated cylinder mass flow and exhaust gas recirculation flow in a state observer, which calculates exhaust and intake burned gas fractions and resulting percent oxygen in the intake manifold. During unthrottled operation, estimation is corrected by an adaptive disturbance estimator, which operates to correct all input disturbances under conditions of higher EGR and to correct only MAF flow values under lower EGR conditions. Steps for operation of the state observer and for determining or estimating input conditions to the state observer are set forth.

Exhaust system for a lean burn internal combustion engine

Abstract: An exhaust system for an internal combustion engine has a catalysed ceramic wall flow particulate filter coated with a washcoat composition. The washcoat composition includes an oxidation catalyst of at least one platinum group metal and a NO x absorbent. The washcoat composition has a D50 of less than or equal to 8 μm. The NO x absorbent absorbs NO x contained in an exhaust gas when the composition of the exhaust gas is lambda >1, and releases the NO x absorbed in the NO x absorbent when the exhaust gas composition is 1≦lambda. The exhaust system has a platinum group metal catalyst upstream of the filter for oxidising NO to NO 2 at least when the composition of the exhaust gas is lambda >1. The uncoated portions of the ceramic wall flow particulate filter have a porosity of >40% and a mean pore size of 8-25 μm.

The mechanism of NOx storage/reduction over lean-burn automotive catalysts

Abstract: Abstract This paper shows the behavior of a Pt/Ba/γ–Al2O3 automotive catalyst in a fixed bed reactor during cyclic operation at lean and rich gas phase conditions at short (seconds) and long (hours) cycling times at different temperatures. Reactor exit gas phase concentrations have been measured and catalyst properties have been determined before and after selective cycling experiments. The experimental results indicate that: (i) Upon 9 h lean and 15 h rich cycling, the NO oxidation efficiency of the catalyst decreases with time while incomplete regeneration is seen, even after 15 h rich exposure with H2. The cyclic steady state is reached after 3 lean/rich cycles, at which only 60% of the available barium is involved in the NOx storage/reduction. (ii) The BET surface area, pore volume, and Pt dispersion decrease by approximately 40%, which may be a result of masking of Pt sites or blocking of pores of the barium clusters as BaCO3 becomes Ba(NO3)2. Experiments with catalyst pellet sizes of 180 and 280 μm along with XPS measurements show that blocking of catalyst pellet pores is not taking place. (iii) When applying lean/rich cycling in the order of seconds, it appears that catalyst history and lean/rich timing affect the number of cycles required to arrive at a closed N balance. XRD results after lean exposure confirm the formation of barium nitrate in the bulk of the barium cluster.

Linear Parameter-Varying Lean Burn Air-Fuel Ratio Control

Abstract: Maximization of the fuel economy of the lean burn SI engine strongly depends on precise air-fuel ratio control. A great challenge associated with the air-fuel ratio feedback control is the large variable time delay in the exhaust system. In this paper, a systematic development of an air-fuel ratio controller based on post-LNT UEGO sensor feedback using linear parameter-varying (LPV) control is presented. Satisfactory stability and disturbance rejection performance is obtained in the face of the variable time delay. The LPV controller is simplified to an explicit parameterized gain scheduled 1st order controller form for the ease of implementation. A Ford F-150 truck with a V8 4.6 Liter lean burn engine was used to demonstrate the LPV air-fuel ratio control design. Both simulation and experimental results demonstrate that the designed controller regulates the tailpipe air-fuel ratio to the preset reference for the full engine operating range.

Laser Ignition of an IC Test Engine using an Nd: YAG Laser and the Effect of Key Laser Parameters on Engine Combustion Performance

Abstract: The use of laser energy to ignite gas and liquid based fuel-air mixtures has been the subject of a number of studies and laboratory experiments at a fundamental level over the past 30 years. Yet, the practical implementation of this laser application has still to be fully realised in a commercial automotive application. Laser Ignition (LI), as a replacement for Spark Ignition (SI) in the internal combustion (IC) engines of automotive vehicles, offers several potential advantages including extending lean burn capability, reducing the cyclic variants between combustion cycles and reducing the overall ignition package costs, weight and energy requirements. The continued development of increasingly compact and efficient laser sources and new associated laser beam delivery techniques have provided the basis for significant steps forward in research towards practical proof-of-concept demonstration of LI in engines for automotive vehicles. This paper reports on some results of research recently undertaken in the Department of Engineering, University of Liverpool, in which a Q-switched Nd:YAG laser operating at 1064 nm wavelength has been used to successfully ignite and run (for extended periods) one cylinder of a 4-cylinder internal combustion (IC) test engine. The variation of several laser parameters and their effect on the engine performance are reported; namely, pulse energies of 5–20 mJ, pulse lengths of 6–15 ns and focused beam waist diameters at the combustion point of 40–100μm. The engine performance was measured in terms of changes in Coefficient of Variant (COV) in both Indicated Mean Effective Pressure (IMEP) and the Peak Cylinder Pressure Position (PPP). Further experiments on the focal position of laser ignition were undertaken.

Development of a fuel stratification spark ignition engine

Abstract: A fuel stratification concept is being researched and developed in a three-valve twin-spark ignition engine. This concept requires that two different fuels or fuel components be introduced into the cylinder separately through two independent inlet ports. The fuels will be stratified laterally by means of strong tumble in the cylinder. Similar to the traditional air/fuel stratification engine, this fuel stratification engine can operate in very lean mixture or high exhaust gas dilution at part loads to reduce fuel consumption and NO;( emissions. While at high-load operation, a higher compression ratio may be allowed owing to a potential increase in antiknock features if the lower research octane number (RON) fuel or component is ignited first, leaving the higher RON fuel in the end gas region. As a result, the fuel economy can be improved not only at part loads but possibly at full loads as well. This paper reports the development of such a fuel stratification engine. Firstly, the intake system of the engine was modified to produce a strong tumble flow which was measured by a digital particle image velocimetry (PIV) system. Then, a two-tracer planar laser induced fluorescence (PLIF) system was developed to visualize the fuel stratification in the cylinder. The engine combustion at part and full loads was also tested and analysed from cylinder pressure history. These research results show that the present strong tumble flow was characterized by a symmetrically distributed mean velocity in the intake stroke and a very small velocity component along the direction of the tumble rotational axis in the compression stroke. This flowfield created good fuel stratification laterally. The lean burn limit was considerably extended at part loads, and the knock limit at high loads also had a noticeable difference when higher and lower RON fuels respectively were ignited first.

Alumina-based lean NOx trap system and method of use

Abstract: An alumina-based lean NO x trap system for use in a lean burn engine such as a diesel engine is provided which includes at least one alumina-based lean NO x trap comprising a catalyst, an alumina NO x absorbent material, and optionally, from 0 to about 4 wt % of an alkaline earth metal oxide. The system preferably includes at least a first alumina-based lean NO x trap, and a second lean NO x trap which is positioned downstream from the first lean NO x trap in an engine exhaust. The second lean NO x trap may comprise an alumina-based trap or a conventional lean NO x trap. The lean NO x trap system converts at least a portion of NO x contained in the exhaust gas to N 2 at a temperature between about 150° C. to about 500° C. The alumina-based lean NO x trap system also undergoes efficient desulphurization and maintains its activity with extended use.

Reforming diesel fuel for NOx reduction

Abstract: The selective catalytic reduction of nitrogen oxides (especially NO and NO 2 ) in exhaust from diesel and other lean burn engines is improved by use of a compact hyperplasma reactor for generating ozone and other highly oxidizing species in a stream of air. A portion of the ozone containing air stream is blown directly into the exhaust for oxidizing NO to NO 2 . The other portion of plasma treated air is used to fractionate and reform a volume of diesel fuel to produce low molecular weight hydrocarbons and oxidized hydrocarbons to be added to the exhaust as NO 2 reductants in the catalytic reduction.

Method for processing combustion exhaust gas containing soot particles and NOx

Abstract: The invention relates to a system and a method for processing exhaust gas of an internal combustion engine such as a diesel engine. The disclosed system and method can be particularly suitable to the diesel engine that usually operates in a lean burn condition without the occurrence of a periodic high-load condition in view of its combustion characteristics. According to the system and method, an exhaust composition containing soot particles and gaseous components are processed to remove the soot particles and to reduce the amount of NOx compounds. The soot particles are first filtered with a filter that passes gaseous components of the composition and collecting the soot particles. The collected soot particles are oxidized in the presence of a light-activated redox catalyst to turn to smaller molecules that can pass through the filter. The NOx compounds are temporarily adsorbed by an adsorber and reduced in the presence of a light-activated redox catalyst to turn to N 2 .

Method and device for feeding fuel gas and air in lean burn gas engine

Abstract: PROBLEM TO BE SOLVED: To keep an exhaust gas temperature constant by stably burning a fuel gas even in starting and in operation at a low load in a lean burn gas engine. SOLUTION: In a method for feeding the fuel gas and air in the lean burn gas engine E, the fuel gas fed from a fuel main tube 7 thereto through a fuel tube 11 having a gas pressure regulator 18 is mixed with air by a carburetor 12. The air-fuel mixture is led into the air intake port of a supercharger 5 through a pipeline 9 having a throttle valve 8, compressed by the supercharger 5, and fed to the cylinder 2 of the gas engine E. Also, when the gas engine E is under intermediate and high loads, the fuel gas fed from the fuel main tube 7 thereto through a fuel branch tube 7a is mixed with the air compressed by the supercharger 5 and fed from an air supply tube 4 thereto through an air supply branch tube 4a, and the air-fuel mixture is fed to the cylinder 2. COPYRIGHT: (C)2005,JPO&NCIPI

Extruded Zeolite Catalysts for Lean Exhaust Application

Abstract: In lean burn engines, the conventional automotive catalyst is ineffective in reducing harmful nitric oxide (NOx) wastes. This study has investigated the use of different materials with metal additives as supports for effective NOxcontrolling lean burn catalysts. A series of zeolite (ZSM-5) honeycomb samples were prepared via extrusion with low concentrations of transition metals. Samples were also impregnated with Pt to determine the effect on the catalytic activity. NOx and hydrocarbon conversion under simple lean conditions were measured in a temperature-controlled fixed bed reactor. Ethylene and Propylene, both highly selective NOx reductants, were used separately as the hydrocarbon species. Results have revealed that single and double component zeolites containing Ni, Mn, Cu, and Ag are highly effective in reducing NOx. When these same samples were impregnated with Pt, they achieved conversion rates up to 100% at temperatures less than 300°C at a space velocity of 7000 h. At higher space velocities, up to 80% NO conversion is observed for some catalysts. The performance of the Ni-Co catalyst remains encouraging and is not impaired by moderate aging conditions and by the presence of water.

Non Thermal Plasma NOx Remediation: From Binary Gas Mixture to Lean-Burn Gasoline and Diesel Engine Exhaust

Abstract: Experiments are presented on the plasma removal of NOx (sum of NO and NO2 concentrations) and hydrocarbons in atmospheric pressure gas streams by sub-microsecond pulsed dielectric barrier discharge processing. This investigation presents the effects of electrical input energy, hydrocarbon addition, and water addition on the NOx chemistry and by-products formation. Exhaust gas mixtures with composition containing up to seven gases (CO, CO2, NO, O2, H2O, C3H6, N2) was synthesized. The objective is to reach synthetic gas exhaust simulating diesel and Lean Burn gasoline engine exhaust with propene as a reductant agent. It was established that the observed chemistry in the plasma includes conversion of NO to NO2 as well as the partial oxidation of hydrocarbon. In a given reactor under identical gas composition and equivalent energy density deposition, experimental results show that the main parameter which controls the efficiency of the plasma process is the energy deposition mode. The best results on NOx and hydrocarbon removal efficiencies have been obtained at low input energy per pulse and high discharge frequency. NOx removal improves with increasing input energy deposition and the presence of water in the gas mixture appears to essentially enhance the chemistry process efficiency reducing by this way the energy cost of the processes. As example, for an input energy density of 27 J/L, the fraction of NOx removed was about 60% with an energy cost less than 30 eV/molecule in the case of simulated diesel engine exhaust. The data obtained suggest that aldehydes (CH2O and CH3CHO) are formed in concert with NO oxidation to NO2 in the plasma phase. Methyl nitrate (CH3ONO2) and nitromethane (CH3NO2) are the main R-NOx compounds produced and small amounts of nitrous acid (HNO2) and formic acid (CH2O2) were also detected.

Indirect injection combustion engine

Abstract: PROBLEM TO BE SOLVED: To provide a structure of an indirect injection combustion engine stabilizing lean burn and improve thermal efficiency by optimizing flame jet direction (injection port direction) according to a combustion chamber shape and shortening flame propagation distance. SOLUTION: In the indirect injection combustion engine provided with am auxiliary chamber 4 having smaller volume than a main combustion chamber (main chamber 2) and arranged at a center part of a cylinder head 24 side, an injection hole existing on a boundary of the auxiliary chamber and the main combustion chamber and capable of gas exchange, and an ignition plug 12 igniting air fuel mixture in the auxiliary chamber 4, and burning air fuel mixture in the main combustion chamber by injecting torch shape flame into the main combustion chamber from the injection hole by ignition in the auxiliary chamber 4, one or more first injection holes 6a opening at different angle in relation to a cylinder shaft 42 and directed to a cylinder bore (combustion chamber circumference wall 18) and one or more second injection holes 6b directed to a piston crown surface 10a are provided respectively as the injection holes. COPYRIGHT: (C)2007,JPO&INPIT

Cyclic variations of fuel-droplet distribution during the early intake stroke of a lean-burn stratified-charge spark-ignition engine

Abstract: Lean-burn spark-ignition engines exhibit higher efficiency and lower specific emissions in comparison with stoichiometrically charged engines. However, as the air-to-fuel (A/F) ratio of the mixture is made leaner than stoichiometric, cycle-by-cycle variations in the early stages of in-cylinder combustion, and subsequent indicated mean effective pressure (IMEP), become more pronounced and limit the range of lean-burn operation. Viable lean-burn engines promote charge stratification, the mixture near the spark plug being richer than the cylinder volume averaged value. Recent work has shown that cycle-by-cycle variations in the early stages of combustion in a stratified-charge engine can be associated with variations in both the local value of A/F ratio near the spark plug around ignition timing, as well as in the volume averaged value of the A/F ratio. The objective of the current work was to identify possible sources of such variability in A/F ratio by studying the in-cylinder field of fuel-droplet distribution during the early intake stroke. This field was visualised in an optical single-cylinder 4-valve pentroof-type spark-ignition engine by means of laser-sheet illumination in planes parallel to the cylinder head gasket 6 and 10 mm below the spark plug. The engine was run with port-injected isooctane at 1500 rpm with 30% volumetric efficiency and air-to-fuel ratio corresponding to both stoichiometric firing (A/F=15, Φ =1.0) and mixture strength close to the lean limit of stable operation (A/F=22, Φ =0.68). Images of Mie intensity scattered by the cloud of fuel droplets were acquired on a cycle-by-cycle basis. These were studied in order to establish possible correlations between the cyclic variations in size, location and scattered-light intensity of the cloud of droplets with the respective variations in IMEP. Because of the low level of Mie intensity scattered by the droplets and because of problems related to elastic scattering on the walls of the combustion chamber, as well as problems related to engine “rocking” at the operating conditions close to the misfire limit, the acquired images were processed for background subtraction by using a PIV-based data correction algorithm. After this processing, the arrival and leaving timings of fuel droplets into the illuminated plane were found not to vary significantly on a cycle-by-cycle basis but the recorded cycle-by-cycle variations in Mie intensity suggested that the amount of fuel in the cylinder could have been 6–26% greater for the “strong” cycles with IMEP 115% higher than the average IMEP, than the ones imaged for “weak” cycles at less than 85% the average IMEP. This would correspond to a maximum cyclic variability in the in-cylinder equivalence ratio Φ of the order of 0.17.

NOx reduction in lean burn engine exhaust

Abstract: The nitric oxide (NO) and nitrogen dioxide (NO 2 ) content of lean-burn engine exhaust is beneficially prepared for selective catalytic reduction (SCR) of these oxides to nitrogen by two sidestream additions to the exhaust. An ozone-containing air stream is added to the exhaust to affect oxidation of NO to NO 2 . And a hydrocarbon(s) fuel constituent is added to a second humidified ozone-containing air stream and that mixture subjected to UV radiation. Strongly oxidizing hydroxyl radicals are formed by interaction of ozone, water, and UV radiation for reaction with the hydrocarbon. The resulting partially oxidized hydrocarbons (Pox) are added to the exhaust, providing effective reduction materials for the SCR of NO 2 to nitrogen and water.

Method for operating a lean burn operable internal combustion engine

Abstract: The operating process is for a lean-burn internal combustion engine (1) with a first cylinder group (2a) having a first exhaust gas line (3a) with an exhaust gas supercharger (7); and a second cylinder group (2b) with a second exhaust gas line (3b). During lean burn, the first exhaust gas line is closed off from the setting element (6).

An emission control system for an engine

Abstract: A system is disclosed for regenerating a lean NOx trap 104 arranged to receive exhaust gases from a lean burn engine 101 in which during regeneration of the lean NOx trap 104 the flow of exhaust gases through the lean NOx trap 104 is prevented, the exhaust gasses are diverted past the lean NOx trap 104 through a bypass passage 190 and the outlet from the lean NOx trap 104 is connected to an air intake 112 of the engine 101 so as to recycle the products of regeneration through the engine 101. In a preferred embodiment two lean NOx traps 4A, 4B are arranged in parallel thereby permitting one of the lean NOx traps 4A, 4B to be regenerated while the other of the two lean NOx traps 4B, 4A continues to store NOx.

Effect of Hydrogen Content in Hydrogen Natural-Gas Fuel Mixtures on Emissions in a Lean-Burn IC Engine

Abstract: The influence of hydrogen content in hydrogen-natural gas fuel mixtures on the emissions of a lean-burn spark ignition engine has been examined under representative operating conditions, a mid load and a high load. The hydrogen content in the fuel gas mixtures was varied from 0 to 30% with the balance made up of natural gas. The primary effect on emissions was to influence the tradeoff between NOx and hydrocarbon emissions. At the mid-load condition, increasing the hydrogen content from 0 to 15% at constant equivalence ratio reduced the HC emissions by 80% with little change in NOx emissions. Increasing from 15 to 30% hydrogen content reduced the HC emissions a further 50% but increased the NOx emissions by 16%. At the high load condition, the overall result of increasing the hydrogen content was to increase the NOx emissions substantially without significantly reducing the HC emissions. The impact of increasing hydrogen content on engine efficiency is similar to the impact on hydrocarbon emissions. At the mid-load condition, engine efficiency was increased by increasing hydrogen content, but with diminishing returns. An increase from 0 to 5% hydrogen content provides a significant benefit under marginal combustion conditions but further increases in hydrogen content are less effective.Copyright © 2005 by ASME

Double-cylinder circulating internal combustion engine and its method for mainly realizing thermal insulation and homogeneous lean burn

Abstract: The present invention relates to one kind of reciprocating internal combustion engine with several small double-cylinder circulating systems and its method of realizing thermal insulation and lean combustion. The present invention aims at providing one kind of internal combustion engine with relatively simple structure and without efficiency and exhaust problems. The internal combustion engine has compression and expansion completed in separated cylinders, independent combustor separated with the movable portioning board into inner chamber and outer chamber, combustion only inside the inner chamber, aiding jetting with compressed work medium, and altering output torque vian altering the start-stop combination of the small systems rather than regulating the air/fuel ratio, to realize thermal insulation and lean combustion, lower fuel consumption and reduce exhaust.

Lean burn internal combustion engine, and method for forming air-fuel mixture for the same

Abstract: PROBLEM TO BE SOLVED: To provide a lean burn internal combustion engine capable of realizing consistent combustion, reducing NOx emission, and enhancing the fuel consumption. SOLUTION: A lean burn internal combustion engine comprises a fuel injection valve to inject fuel in an air intake passage, a control means to control the injection timing by the fuel injection valve so that a part of fuel required according to the running condition is injected before an air intake valve is opened, and the remaining fuel is injected after the air intake valve is opened, and a piston in which the remaining fuel injected after the air intake valve is opened is stored in a cavity formed in a top surface of the piston, the fuel/air mixture is formed within the cavity, and the fuel/air mixture is lead in a vicinity of an ignition plug in the second half of the compression stroke. The fuel/air mixture of the air-fuel ratio lower than the homogeneous fuel/air mixture formed over the entire combustion chamber is formed in the cavity, and led in a vicinity of the ignition plug in the second half of the compression stroke, and consistent combustion can be realized. NOx emission and the fuel consumption can be reduced by adequately controlling the air-fuel ratio. COPYRIGHT: (C)2005,JPO&NCIPI

Device for purifying exhaust gas of an internal combustion engine

Abstract: A NOx occluding and reducing catalyst 7 is arranged in the exhaust gas passage 2 of a lean burn engine 1 . When the engine 1 is in operation at a lean air-fuel ratio, the operating air-fuel ratio is changed over to a rich air-fuel ratio for a short period of time to execute the rich spike operation for reducing and purifying the NOx occluded in the NOx occluding and reducing catalyst. At the time of the rich spike operation during the lean burn operation being supercharged by a supercharger 45 provided in the intake air passage 4 , an electronic control unit 30 of the engine so sets the richness degree of the engine operating air-fuel ratio as to decrease with an increase in the supercharged pressure. This prevents the HC and CO components from flowing out in large amounts to the downstream of the catalyst 7 due to blow-by, and prevents a decrease in the NOx reduction efficiency of the NOx occluding and reducing catalyst.