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Technical Paper

1.9-Liter Four-Cylinder HCCI Engine Operation with Exhaust Gas Recirculation

2001-05-07
2001-01-1894
We present the effect of EGR, at a set fuel flow rate and intake temperature, on the operating parameters of timing of combustion, duration of combustion, power output, thermal efficiency, and NOx emission; which is remarkably low. We find that addition of EGR at constant inlet temperature and constant fuel flow rate has little effect on HCCI parameter of start of combustion (SOC). However, burn duration is highly dependent on the amount of EGR inducted. The experimental setup at UC Berkeley uses a 1.9-liter 4-cylinder diesel engine with a compression ratio of 18.8:1 (offered on a 1995 VW Passat TDI). The engine was converted to run in HCCI mode by addition of an 18kW air pre-heater installed in the intake system. Pressure traces were obtained using four water-cooled quartz pressure transducers, which replaced the Diesel fuel injectors. Gaseous fuel (propane or butane) flowed steadily into the intake manifold.
Journal Article

1000-Hour Durability Evaluation of a Prototype 2007 Diesel Engine with Aftertreatment Using B20 Biodiesel Fuel

2009-11-02
2009-01-2803
A prototype 2007 ISL Cummins diesel engine equipped with a diesel oxidation catalyst (DOC), diesel particle filter (DPF), variable geometry turbocharger (VGT), and cooled exhaust gas recirculation (EGR) was tested at Southwest Research Institute (SwRI) under a high-load accelerated durability cycle for 1000 hours with B20 soy-based biodiesel blends and ultra-low sulfur diesel (ULSD) fuel to determine the impact of B20 on engine durability, performance, emissions, and fuel consumption. At the completion of the 1000-hour test, a thorough engine teardown evaluation of the overhead, power transfer, cylinder, cooling, lube, air handling, gaskets, aftertreatment, and fuel system parts was performed. The engine operated successfully with no biodiesel-related failures. Results indicate that engine performance was essentially the same when tested at 125 and 1000 hours of accumulated durability operation.
Technical Paper

A Co-Simulation Environment for Virtual Prototyping of Ground Vehicles

2007-10-30
2007-01-4250
The use of virtual prototyping early in the design stage of a product has gained popularity due to reduced cost and time to market. The state of the art in vehicle simulation has reached a level where full vehicles are analyzed through simulation but major difficulties continue to be present in interfacing the vehicle model with accurate powertrain models and in developing adequate formulations for the contact between tire and terrain (specifically, scenarios such as tire sliding on ice and rolling on sand or other very deformable surfaces). The proposed work focuses on developing a ground vehicle simulation capability by combining several third party packages for vehicle simulation, tire simulation, and powertrain simulation. The long-term goal of this project consists in promoting the Digital Car idea through the development of a reliable and robust simulation capability that will enhance the understanding and control of off-road vehicle performance.
Technical Paper

A Comparative Study of Hydraulic Hybrid Systems for Class 6 Trucks

2013-04-08
2013-01-1472
In order to reduce fuel consumption, companies have been looking at hybridizing vehicles. So far, two main hybridization options have been considered: electric and hydraulic hybrids. Because of light duty vehicle operating conditions and the high energy density of batteries, electric hybrids are being widely used for cars. However, companies are still evaluating both hybridization options for medium and heavy duty vehicles. Trucks generally demand very large regenerative power and frequent stop-and-go. In that situation, hydraulic systems could offer an advantage over electric drive systems because the hydraulic motor and accumulator can handle high power with small volume capacity. This study compares the fuel displacement of class 6 trucks using a hydraulic system compared to conventional and hybrid electric vehicles. The paper will describe the component technology and sizes of each powertrain as well as their overall vehicle level control strategies.
Journal Article

A Comparison of Experimental and Modeled Velocity in Gasoline Direct-Injection Sprays with Plume Interaction and Collapse

2017-03-28
2017-01-0837
Modeling plume interaction and collapse for direct-injection gasoline sprays is important because of its impact on fuel-air mixing and engine performance. Nevertheless, the aerodynamic interaction between plumes and the complicated two-phase coupling of the evaporating spray has shown to be notoriously difficult to predict. With the availability of high-speed (100 kHz) Particle Image Velocimetry (PIV) experimental data, we compare velocity field predictions between plumes to observe the full temporal evolution leading up to plume merging and complete spray collapse. The target “Spray G” operating conditions of the Engine Combustion Network (ECN) is the focus of the work, including parametric variations in ambient gas temperature. We apply both LES and RANS spray models in different CFD platforms, outlining features of the spray that are most critical to model in order to predict the correct aerodynamics and fuel-air mixing.
Technical Paper

A Comparison of the Effect of Combustion Chamber Surface Area and In-Cylinder Turbulence on the Evolution of Gas Temperature Distribution from IVC to SOC: A Numerical and Fundamental Study

2006-04-03
2006-01-0869
It has previously been shown experimentally and computationally that the process of Homogeneous Charge Compression Ignition (HCCI) is very dependent on the pre-combustion gas temperature field. This study looks in detail at how temperature fields can evolve by comparing results of two combustion chamber designs, a piston with a square bowl and a disk shaped piston, and relates these temperature fields to measured HCCI combustion durations. The contributions of combustion chamber surface area and turbulence levels to the gas temperature evolution are considered over the crank angle range from intake valve closure to top-dead-center. This is a CFD study, whose results were transformed into traditional analysis methods of convective heat transfer (q=h*A*ΔT) and boundary layers.
Technical Paper

A Computer Generated Reduced Iso-Octane Chemical Kinetic Mechanism Applied to Simulation of HCCI Combustion

2002-10-21
2002-01-2870
This paper shows how a computer can systematically remove non-essential chemical reactions from a large chemical kinetic mechanism. The computer removes the reactions based upon a single solution using a detailed mechanism. The resulting reduced chemical mechanism produces similar numerical predictions significantly faster than predictions that use the detailed mechanism. Specifically, a reduced chemical kinetics mechanism for iso-octane has been derived from a detailed mechanism by eliminating unimportant reaction steps and species. The reduced mechanism has been developed for the specific purpose of fast and accurate prediction of ignition timing in an HCCI engine. The reduced mechanism contains 199 species and 383 reactions, while the detailed mechanism contains 859 species and 3606 reactions. Both mechanisms have been used in numerical simulation of HCCI combustion.
Technical Paper

A Decoupled Model of Detailed Fluid Mechanics Followed by Detailed Chemical Kinetics for Prediction of Iso-Octane HCCI Combustion

2001-09-24
2001-01-3612
We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. The methodology judiciously uses a fluid mechanics code followed by a chemical kinetics code to achieve great reduction in the computational requirements; to a level that can be handled with current computers. In previous papers, our sequential, multi-zone methodology has been applied to HCCI combustion of short-chain hydrocarbons (natural gas and propane). Applying the same procedure to long-chain hydrocarbons (iso-octane) results in unacceptably long computational time. In this paper, we show how the computational time can be made acceptable by developing a segregated solver. This reduces the run time of a ten-zone problem by an order of magnitude and thus makes it much more practical to make combustion studies of long-chain hydrocarbons.
Technical Paper

A Detailed Chemical Kinetic Analysis of Low Temperature Non-Sooting Diesel Combustion

2005-04-11
2005-01-0923
We have developed a model of the diesel fuel injection process for application to analysis of low temperature non-sooting combustion. The model uses a simplified mixing correlation and detailed chemical kinetics to analyze a parcel of fuel as it moves along the fuel jet, from injection to evaporation and ignition. The model predicts chemical composition and soot precursors, and is applied at conditions that result in low temperature non-sooting combustion. Production of soot precursors is the first step toward production of soot, and modeling precursor production is expected to give insight into the overall evolution of soot inside the engine. The results of the analysis show that the model has been successful in describing many of the observed characteristics of low temperature combustion.
Journal Article

A Framework for Quantifying Measurement Uncertainties and Uncertainty Propagation in HCCI/LTGC Engine Experiments

2017-03-28
2017-01-0736
In this paper, a framework for estimating experimental measurement uncertainties for a Homogenous Charge Compression Ignition (HCCI)/Low-Temperature Gasoline Combustion (LTGC) engine testing facility is presented. Detailed uncertainty quantification is first carried out for the measurement of the in-cylinder pressure, whose variations during the cycle provide most of the information for performance evaluation. Standard uncertainties of other measured quantities, such as the engine geometry and speed, the air and fuel flow rate and the intake/exhaust dry molar fractions are also estimated. Propagating those uncertainties using a Monte Carlo simulation and Bayesian inference methods then allows for estimation of uncertainties of the mass-average temperature and composition at IVC and throughout the cycle; and also of the engine performances such as gross Integrated Mean Effective Pressure, Heat Release and Ringing Intensity.
Journal Article

A Hydrogen Direct Injection Engine Concept that Exceeds U.S. DOE Light-Duty Efficiency Targets

2012-04-16
2012-01-0653
Striving for sustainable transportation solutions, hydrogen is often identified as a promising energy carrier and internal combustion engines are seen as a cost effective consumer of hydrogen to facilitate the development of a large-scale hydrogen infrastructure. Driven by efficiency and emissions targets defined by the U.S. Department of Energy, a research team at Argonne National Laboratory has worked on optimizing a spark-ignited direct injection engine for hydrogen. Using direct injection improves volumetric efficiency and provides the opportunity to properly stratify the fuel-air mixture in-cylinder. Collaborative 3D-CFD and experimental efforts have focused on optimizing the mixture stratification and have demonstrated the potential for high engine efficiency with low NOx emissions. Performance of the hydrogen engine is evaluated in this paper over a speed range from 1000 to 3000 RPM and a load range from 1.7 to 14.3 bar BMEP.
Technical Paper

A Multi-Zone Model for Prediction of HCCI Combustion and Emissions

2000-03-06
2000-01-0327
Homogeneous Charge Compression Ignition (HCCI) combustion is a process dominated by chemical kinetics of the fuel-air mixture. The hottest part of the mixture ignites first, and compresses the rest of the charge, which then ignites after a short time lag. Crevices and boundary layers generally remain too cold to react, and result in substantial hydrocarbon and carbon monoxide emissions. Turbulence has little effect on HCCI combustion, and may be most important as a factor in determining temperature gradients and boundary layer thickness inside the cylinder. The importance of thermal gradients inside the cylinder makes it necessary to use an integrated fluid mechanics-chemical kinetics code for accurate predictions of HCCI combustion. However, the use of a fluid mechanics code with detailed chemical kinetics is too computationally intensive for today's computers.
Journal Article

A New Automotive Air Conditioning System Simulation Tool Developed in MATLAB/Simulink

2013-04-08
2013-01-0850
Accurate evaluation of vehicles' transient total power requirement helps achieving further improvements in vehicle fuel efficiency. When operated, the air-conditioning (A/C) system is the largest auxiliary load on a vehicle, therefore accurate evaluation of the load it places on the vehicle's engine and/or energy storage system is especially important. Vehicle simulation models, such as "Autonomie," have been used by OEMs to evaluate vehicles' energy performance. However, the load from the A/C system on the engine or on the energy storage system has not always been modeled in sufficient detail. A transient A/C simulation tool incorporated into vehicle simulation models would also provide a tool for developing more efficient A/C systems through a thorough consideration of the transient A/C system performance. The dynamic system simulation software MATLAB/Simulink® is frequently used by vehicle controls engineers to develop new and more efficient vehicle energy system controls.
Technical Paper

A Numerical Investigation on Scalability and Grid Convergence of Internal Combustion Engine Simulations

2013-04-08
2013-01-1095
Traditional Lagrangian spray modeling approaches for internal combustion engines are highly grid-dependent due to insufficient resolution in the near nozzle region. This is primarily because of inherent restrictions of volume fraction with the Lagrangian assumption together with high computational costs associated with small grid sizes. A state-of-the-art grid-convergent spray modeling approach was recently developed and implemented by Senecal et al., (ASME-ICEF2012-92043) in the CONVERGE software. The key features of the methodology include Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, which enables use of cell sizes smaller than the nozzle diameter. This modeling approach was rigorously validated against non-evaporating, evaporating, and reacting data from the literature.
Technical Paper

A Preliminary Study of Energy Recovery in Vehicles by Using Regenerative Magnetic Shock Absorbers

2001-05-14
2001-01-2071
Road vehicles can expend a significant amount of energy in undesirable vertical motions that are induced by road bumps, and much of that is dissipated in conventional shock absorbers as they dampen the vertical motions. Presented in this paper are some of the results of a study aimed at determining the effectiveness of efficiently transforming that energy into electrical power by using optimally designed regenerative electromagnetic shock absorbers. In turn, the electrical power can be used to recharge batteries or other efficient energy storage devices (e.g., flywheels) rather than be dissipated. The results of the study are encouraging - they suggest that a significant amount of the vertical motion energy can be recovered and stored.
Journal Article

A Progress Review on Soot Experiments and Modeling in the Engine Combustion Network (ECN)

2016-04-05
2016-01-0734
The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.
Technical Paper

A Robust Preignition Rating Methodology: Evaluating the Propensity to Establish Propagating Flames under Real Engine Conditions

2017-10-08
2017-01-2241
In this work, an experimental and analysis methodology was developed to evaluate the preignition propensity of fuels and engine operating conditions in an SI engine. A heated glow plug was introduced into the combustion chamber to induce early propagating flames. As the temperature of the glowplug varied, both the fraction of cycles experiencing these early flames and the phasing of this combustion in the engine cycle varied. A statistical methodology for assigning a single-value to this complex behavior was developed and found to have very good repeatability. The effects of engine operating conditions and fuels were evaluated using this methodology. While this study is not directly studying the so-called stochastic preignition or low-speed preignition problem, it studies one aspect of that problem in a very controlled manner.
Technical Paper

A Sequential Fluid-Mechanic Chemical-Kinetic Model of Propane HCCI Combustion

2001-03-05
2001-01-1027
We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers.
Technical Paper

A Simple Fan Model for Underhood Thermal Management Analyses

2002-03-04
2002-01-1025
This work presents a simple fan model that is based on the actuator disk approximation, and the blade element and vortex theory of a propeller. A set of equations are derived that require as input the rotational speed of the fan, geometric fan data, and the lift and drag coefficients of the blades. These equations are solved iteratively to obtain the body forces generated by the fan in the axial and circumferential directions. These forces are used as momentum sources in a CFD code to simulate the effect of the fan in an underhood thermal management simulation. To validate this fan model, a fan experiment was simulated. The model was incorporated into the CFD code STAR-CD and predictions were generated for axial and circumferential air velocities at different radial positions and at different planes downstream of the fan. The agreement between experimental measurements and predictions is good.
Technical Paper

ALnalyse of System Factors Affecting Performance in Lean NOx Catalysis. 2. The Deleterious Role of Parasitic Homogeneous Hydrocarbon Oxidation on the Performance of High Temperature Lean NOx Catalysts

1998-10-19
982604
Increasing interest in lean NOx catalysis at temperatures between about 300-550°C has led to development of catalytic materials with thermal durability considerably improved over academic benchmark catalysts such as Cu-ZSM-5. The breaching of thermal durability barriers brings new obstacles into focus. Practical implementation of high temperature HC-based lean NOx catalysis entails delivery of hydrocarbons to the catalyst inlet at high temperatures. We have found initially unexpected, but scientifically precedented, phenomena regarding gas-phase kinetic instability of hydrocarbons in diesel exhaust atmospheres above 300°C. Around 300°C, homogeneous hydrocarbon oxidation can begin to occur. Rates of oxidation decrease between about 350-450°C and then increase again at higher temperatures. Some apparent NOx disappearance that does not correspond to chemical reduction of NOx can also occur homogeneously throughout this temperature range.
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