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Technical Paper

Modeling Approach for a Wiremesh Substrate in CFD Simulation

2017-03-28
2017-01-0971
Experimental studies have shown that knitted wiremesh mixers reduce the formation of solid deposits and improve ammonia homogenization in automotive SCR systems. However, their implementation in CFD models remains a major challenge due to the complex WM geometry. It was the aim of the current study to investigate droplet WM interaction. Essential processes, such as secondary droplet generation, wall film formation, and heat exchange, were analyzed in detail and a numerical model was set up. A box with heat resisting glass was used to study urea-water solution spray impingement on a WM under a wide range of operating conditions. High speed videography was used to identify the impingement regimes. Infrared thermography was applied to investigate WM cooling. In order to determine the impact of the WM on the spray characteristics, the droplet spectrum was measured both upstream and downstream of the WM using the laser diffraction method.
Technical Paper

Mean Value Engine Modeling for a Diesel Engine with GT-Power 1D Detail Model

2011-04-12
2011-01-1294
Mean value engine model (MVEM) is the basis of control design for advanced internal combustion engines. The engine performance transient process usually takes a few cycles. The MVEM provides an adequate accurate description of the engine dynamics with reasonable approximation by ignoring the heat loss and sub-cycle events. MVEM is very important for engine system control development, especially when the modern engine becomes more and more complicated when equipped with throttle, turbocharger and after-treatment systems. Usually the MVEM is developed based on data from engine tests, which is a costly and time consuming process. In this paper, the air path MVEM modeling method based on the 1D detail model is discussed for a turbocharged diesel engine. Simulation is applied to demonstrate the effectiveness of this new method. This approach could be used to get the MVEM for control design even before the prototype engine is available.
Technical Paper

Characterization of DPF Ash for Development of DPF Regeneration Control and Ash Cleaning Requirements

2011-04-12
2011-01-1248
The accumulation of ash in a Diesel Particulate Filter (DPF) eventually results in an increase in the pressure drop across the exhaust system component. This situation translates into a reduced capacity for soot, and requires an increased frequency of active regenerations to eliminate this soot. For heavy duty diesel applications, the lifetime of the DPF is long enough to expect that cleaning of the ash from the DPF will be required. The physico-chemical characteristics of the ash as a function of temperature and time will have an impact on the effectiveness of this cleaning. To develop a deeper understanding of this subject, four different samples of ash were characterized in this study that were collected under active or passive regeneration from exhaust systems of engines running on different fuels: ultra low sulfur diesel (ULSD), and biodiesel fuels B20 and B100. The lubricant, an API CJ-4 oil, was used for each engine test.
Technical Paper

Analysis of Multivariable Controller Designs for Closed-Loop Diesel Engine Air System Control

2013-04-08
2013-01-0327
As diesel engine emissions standards become increasingly stringent, a commonly employed method of emissions reduction by engine manufacturers is active control of inducted air and the use of EGR. A common system configuration includes actuators such as an EGR valve and a VGT are used to manipulate the air flow through a diesel engine to control desired in-cylinder conditions so that the combustion event produces reduced engine out emissions. This paper evaluates four different controller designs for control of a diesel engine air path using a VGT & EGR valve in order to explore trade-offs between system performance and system complexity: three built up from SISO transfer functions and one that is a fully multivariable design. Various performance metrics are analyzed to gauge the relative difference in performance capability while attempting to maintain simple controller architecture.
Technical Paper

Microstructural Analysis of Deposits on Heavy-Duty EGR Coolers

2013-04-08
2013-01-1288
Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with NOX emissions standards and has negative impacts on cooler sizing and engine performance. In order to improve our knowledge of cooler fouling as a function of engine operating parameters and to predict and enhance performance, 19 tube-in-shell EGR coolers were fouled using a 5-factor, 3-level design of experiments with the following variables: (1) EGR flow rate, (2) EGR inlet gas temperature, (3) coolant temperature, (4) soot level, and (5) hydrocarbon concentration. A 9-liter engine and ULSD fuel were used to form the cooler deposits. Coolers were run until the effectiveness stabilized, and then were cooled down to room temperature and run for an additional few hours in order to measure the change in effectiveness due to shut down. The coolers were cut open and the mass per unit area of the deposit was measured as a function of distance down the tube.
Technical Paper

Engine Test Protocol for Accelerated Ash Loading of a Diesel Particulate Filter

2011-04-12
2011-01-0607
Diesel particulate filters with a quantity of ash corresponding to the service interval (4500 hours) are needed to verify that soot loading model predictions remain accurate as ash accumulates in the DPF. Initially, long-term engine tests carried out for the purpose of assessing engine and aftertreatment system durability provided ash-loaded DPFs for model verification. However, these DPFs were found to contain less ash than expected based on lube oil consumption, and the ash was distributed uniformly along the length of the inlet channels, as opposed to being in the form of a plug at the outlet end of those channels. Thus, a means of producing DPFs with higher quantities of ash, distributed primarily as plugs, was required. An engine test protocol was developed for this purpose; it included the following: 1) controlled dosing of lube oil into the fuel feeding the engine, 2) formation of a soot cake within the DPF, and 3) periodic active regenerations to eliminate the soot cake.
Technical Paper

Integrated Simulation of Engine Performance and AFR Control of a Stoichiometric Compression Ignition (SCI) Engine

2011-04-12
2011-01-0698
This paper describes the advantage of the integrated simulation platform and presents the results of performance simulations and the feed-forward air-fuel ratio (AFR) controller design of a new concept stoichiometric compression ignition (SCI) engine based on this platform. In this integrated simulation environment, the SCI engine was modeled in GT-Power and a simplified production engine control module (ECM) is implemented in Simulink/Matlab for the performance simulation and AFR control. The integrated engine and controller model was used to investigate constant-speed load-acceptance (CSLA) performance. During performance simulation, searching for operating conditions is difficult but critical for performance analysis. Trial and error method would require a long time to do. Based on the integrated simulation, a proportional-integral (PI) controller was designed to find the accurate operating conditions.
Technical Paper

Extraction of Liquid Water from the Exhaust of a Diesel Engine

2015-09-29
2015-01-2806
Introducing water in a diesel engine has been known to decrease peak combustion temperatures and decrease NOx emissions. This however, has been limited to stationary and marine applications due to the requirement of a separate water supply tank in addition to the fuel tank, thereby a two-tank system. Combustion of hydrocarbon fuels produce between 1.35 (Diesel) and 2.55 times (Natural Gas) their mass in water. Techniques for extracting this water from the exhaust flow of an engine have been pursued by the United States department of defense (DOD) for quite some time, as they can potentially reduce the burden of supply of drinking water to front line troops in theater. Such a technology could also be of value to engine manufacturers as it could enable water injection for performance, efficiency and emissions benefits without the drawbacks of a two-tank system.
Technical Paper

Modeling Evaporating Diesel Sprays Using an Improved Gas Particle Model

2013-04-08
2013-01-1598
Accurate modeling of evaporating sprays is critical for diesel engine simulations. The standard spray and evaporation models in KIVA-3V tend to under-predict the vapor penetration, especially at high ambient pressure conditions. A sharp decrease of vapor penetration gradient is observed soon after the liquid spray is completely evaporated due to the lack of momentum sources beyond the liquid spray region. In this study, a gas particle model is implemented in KIVA-3V which tracks the momentum sources resulting from the evaporated spray. Lagrangian tracking of imaginary gas particles is considered until the velocity of the gas particle is comparable to that of the gas phase velocity. The gas particle continuously exchanges momentum with the gas phase and as a result the vapor penetrations are improved. The results using the present gas particle model is compared with experimental data over a wide range of ambient conditions and good levels of agreement are observed in vapor penetration.
Technical Paper

Effects of Numerical Models on Prediction of Cylinder Pressure Ringing in a DI Diesel Engine

2018-04-03
2018-01-0194
Pressure ringing phenomena in internal combustion engine are often observed in cylinder pressure measurement, which may be due to combustion dynamics, pressure oscillation inside the combustion chamber and/or inside a drilled probe hole for cylinder pressure sensor installation. In the present study, combustion process in a production DI diesel engine instrumented with pressure sensors in the cylinder head was analyzed using 3D combustion CFD simulation. Three combustion models (the CTC model with the Shell autoignition model, the Sage model with detailed chemistry, and the ECFM-3Z model) and three reaction mechanisms (the Shell autoignition model, the Chalmers reduced n-heptane mechanism, and the IFP PRF mechanism) were employed to validate their capability in capturing pressure ringing phenomena. Grid size within the drilled hole and speed of sound CFL number were varied to evaluate the effects on pressure ringing prediction.
Technical Paper

A Study of the Filtration and Oxidation Characteristics of a Diesel Oxidation Catalyst and a Catalyzed Particulate Filter

2007-04-16
2007-01-1123
An experimental and modeling study was conducted to study the passive regeneration of a catalyzed particulate filter (CPF) by the oxidation of particulate matter (PM) via thermal and Nitrogen dioxide/temperature-assisted means. Emissions data in the exhaust of a John Deere 6.8 liter, turbocharged and after-cooled engine with a low-pressure loop EGR and a diesel oxidation catalyst (DOC) - catalyzed particulate filter (CPF) in the exhaust system was measured and used for this study. A series of experiments was conducted to evaluate the performance of the DOC, CPF and DOC+CPF configurations at various engine speeds and loads.
Technical Paper

Regulated and Unregulated Exhaust Emissions Comparison for Three Tier II Non-Road Diesel Engines Operating on Ethanol-Diesel Blends

2005-05-11
2005-01-2193
Regulated and unregulated emissions (individual hydrocarbons, ethanol, aldehydes and ketones, polynuclear aromatic hydrocarbons (PAH), nitro-PAH, and soluble organic fraction of particulate matter) were characterized in engines utilizing duplicate ISO 8178-C1 eight-mode tests and FTP smoke tests. Certification No. 2 diesel (400 ppm sulfur) and three ethanol/diesel blends, containing 7.7 percent, 10 percent, and 15 percent ethanol, respectively, were used. The three, Tier II, off-road engines were 6.8-L, 8.1-L, and 12.5-L in displacement and each had differing fuel injection system designs. It was found that smoke and particulate matter emissions decreased with increasing ethanol content. Changes to the emissions of carbon monoxide and oxides of nitrogen varied with engine design, with some increases and some decreases. As expected, increasing ethanol concentration led to higher emissions of acetaldehyde (increases ranging from 27 to 139 percent).
Journal Article

Impact of Ice Formation in Diesel Fuel on Tier 4 Off-Road Engine Performance with High Efficiency Fuel Filtration

2015-09-29
2015-01-2817
The winter of 2013-2014 provided an opportunity to operate off-road vehicles in cold weather for extended time as part of a vehicle/tier 4 diesel engine validation program. An unexpected area of study was the performance of high efficiency, on engine, fuel filters during continuous vehicle operation in cold weather. During the program we observed unexpected premature fuel filter plugging as indicated by an increase in pressure drop across the filter while in service. Field and laboratory testing was completed at John Deere and Donaldson to understand the cause of filter plugging. Although conditions were found where winter fuel additives could cause plugging of high efficiency filters, premature filter plugging occurred even when testing with #1 diesel fuel. This fuel contained no additives and was used at temperatures well above its cloud point.
Journal Article

TMF Life Prediction of High Temperature Components Made of Cast Iron HiSiMo: Part I: Uniaxial Tests and Fatigue Life Model

2014-04-01
2014-01-0915
HiSiMo cast irons are frequently used as material for high temperature components in engines as e.g. exhaust manifolds and turbo chargers. These components must withstand severe cyclic mechanical and thermal loads throughout their service life. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. In this paper (Part I), the low-cycle fatigue (LCF) and TMF properties of HiSiMo are investigated in uniaxial tests and the damage mechanisms are addressed. On the basis of the experimental results a fatigue life model is developed which is based on elastic, plastic and creep fracture mechanics results of short cracks, so that time and temperature dependent effects on damage are taken into account.
Journal Article

TMF Life Prediction of High Temperature Components Made of Cast Iron HiSiMo: Part II: Multiaxial Implementation and Component Assessment

2014-04-01
2014-01-0905
HiSiMo cast irons are frequently used as material for high temperature components in engines as e.g. exhaust manifolds and turbo chargers. These components must withstand severe cyclic mechanical and thermal loads throughout their life cycle. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. In Part I of the paper, a fracture mechanics model for TMF life prediction was developed based on results of uniaxial tests. In this paper (Part II), the model is formulated for three-dimensional stress states, so that it can be applied in a post-processing step of a finite-element analysis. To obtain reliable stresses and (time dependent plastic) strains in the finite-element calculation, a time and temperature dependent plasticity model is applied which takes non-linear kinematic hardening into account.
Journal Article

Studies on the Impact of 300 MPa Injection Pressure on Engine Performance, Gaseous and Particulate Emissions

2013-04-08
2013-01-0897
An investigation has been carried out to examine the influence of up to 300 MPa injection pressure on engine performance and emissions. Experiments were performed on a 4 cylinder, 4 valve / cylinder, 4.5 liter John Deere diesel engine using the Ricardo Twin Vortex Combustion System (TVCS). The study was conducted by varying the injection pressure, Start of Injection (SOI), Variable Geometry Turbine (VGT) vane position and a wide range of EGR rates covering engine out NOx levels between 0.3 g/kWh to 2.5 g/kWh. A structured Design of Experiment approach was used to set up the experiments, develop empirical models and predict the optimum results for a range of different scenarios. Substantial fuel consumption benefits were found at the lowest NOx levels using 300 MPa injection pressure. At higher NOx levels the impact was nonexistent. In a separate investigation a Cambustion DMS-500 fast particle spectrometer, was used to sample and analyze the exhaust gas.
Journal Article

Dynamic Engine Control for HCCI Combustion

2012-04-16
2012-01-1133
One of the factors preventing widespread use of Homogeneous Charge Compression Ignition or HCCI is the challenge of controlling the process under transient conditions. Current engine control technology does not have the ability to accurately control the individual cylinder states needed for consistent HCCI combustion. The material presented here is a new approach to engine control using a physics-based individual cylinder real time model to calculate the engine states and then controlling the engine with this state information. The model parameters and engine state information calculated within the engine controller can be used to calculate the required actuator positions so that the desired mass of air, fuel, and residual exhaust gas are achieved for each cylinder event. This approach offers a solution to the transient control problem that works with existing sensors and actuators.
Journal Article

Water Injection as an Enabler for Increased Efficiency at High-Load in a Direct Injected, Boosted, SI Engine

2017-03-28
2017-01-0663
In a Spark-Ignited engine, there will come a point, as load is increased, where the unburned air-fuel mixture undergoes auto-ignition (knock). The onset of knock represents the upper limit of engine output, and limits the extent of engine downsizing / boosting that can be implemented for a given application. Although effective at mitigating knock, requiring high octane fuel is not an option for most markets. Retarding spark timing can extend the high load limit incrementally, but is still bounded by limits for exhaust gas temperature, and spark retard results in a notable loss of efficiency. Likewise, enriching the air-fuel mixture also decreases efficiency, and has profound negative impacts on engine out emissions. In this current work, a Direct-Injected, Boosted, Spark-Ignited engine with Variable Valve Timing was tested under steady state high load operation. Comparisons were made among three fuels; an 87 AKI, a 91 AKI, and a 110 AKI off-road only race fuel.
Journal Article

Analytical Investigation of Urea Deposits in SCR System

2015-04-14
2015-01-1037
An aqueous urea solution is used as the source of ammonia for selective catalytic reduction (SCR) of NOx to reduce the emissions of NOx in the exhaust of diesel vehicles. However, the decomposition of urea into ammonia is not always complete, resulting in solid urea deposit formation in the decomposition tube or on the SCR catalyst. These solid deposits can impede the flow of the exhaust gases (and uniformity of NH3 supply) and reduce SCR catalyst performance over time. To minimize the formation of urea deposit and to meet EPA NOx emission regulations, it is important to understand the chemistry of formation or removal of the deposit in the decomposition tube and SCR catalyst. In this report, IR spectroscopy, UV-visible spectroscopy, thermogravimetric analysis and elemental analysis have been used to determine the chemical composition of the solid urea deposits formed by the thermal decomposition of urea.
Technical Paper

Numerical Simulations for Spray Characterization of Uneven Multiple Jet-to-Jet Impingement Injectors

2016-04-05
2016-01-0840
Spray structure has a significant effect on emissions and performance of an internal combustion engine. The main objective of this study is to investigate spray structures based on four different multiple jet impingement injectors. These four different multiple jet-to-jet impingement injectors include 1). 4-hole injector (Case 1), which has symmetric inwardly opening nozzles; 2). 5-1-hole (Case 2); 3). 6-2-hole (Case 3); and 4). 7-3-hole (Case 4) which corresponding to 1, 2, 3 numbers of adjacent holes blocked in a 5-hole, 6-hole, and 7-hole symmetrical drill pattern, respectively. All these configurations are basically 4-holes but with different post collision spray structure. Computational Fluid Dynamics (CFD) work of these sprays has been performed using an Eulerian-Lagrangian modelling approach.
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