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Environmental

2006;():1-8. doi:10.1115/ICEF2006-1515.

Conventional switcher or shunting locomotives in North America are powered by a single Electro-Motive Diesel (EMD) 12 or 16 cylinder 645E engine which operate at eight distinct power levels, plus idle, at engine speeds ranging from 250 to 900 rpm, and power ratings of 1125 to 1500 kW. The individual power (notch) settings are weighted according to an established duty cycle to obtain overall fuel consumption and exhaust emission rates. Recently introduced locomotive power systems utilize multiple smaller displacement non-road diesel engines packaged as individual generator sets to obtain a cleaner and more efficient locomotive. This paper compares exhaust emissions and fuel consumption from a conventional switcher locomotive with a single large displacement engine to that of a repowered locomotive utilizing three 345 kW generators.

Commentary by Dr. Valentin Fuster
2006;():9-15. doi:10.1115/ICEF2006-1533.

Total (volatile plus solid) and solid particle size, number, and mass emitted from a 3.8 kW diesel powered generator were characterized using a Scanning Mobility Particle Sizer (SMPS) that measures the size distribution of particles, and a catalytic stripper that facilitates the measurement of solid particles. The engine was operated at a constant speed for six steady-state engine operations ranging from idle to rated power. The solid particle size distributions were mainly monomodal lognormal distributions in nature reflecting a typical soot agglomerate size distribution with a number mean diameter in the size range from 98 nm to 37 nm as the load decreases from high to low. At idle, M6, however, the solid particle distribution was bimodal in nature with a high number of solid nanoparticles in the sub-20 nm size range. It is likely that these solid particles nucleated later in the combustion process from metallic ash typically present in the lube oil. The total particle size distributions exhibited a bimodal structure only at light load, M5, engine operation, where a high number of volatile nanoparticles were observed. The rest of the operating conditions exhibited monomodal distributions although the nature of the particles was vastly different. For the medium load modes, M2, M3, and M4, the particles were mainly solid particles. For the rated power, M1, and idle, M6, modes of engine operation, significant number of volatile particles grew to a size nearing that of soot particles making the distribution monomodal, similar to that of a solid particle distribution. This shows that monomodal distributions are not necessarily solid particle but they can be strongly dominated with volatile particles if significant particle growth takes place like the case at M1, and M6. The total number and mass concentration were extremely high at engine rated power. The number concentration exceeded 1.2 billion particles per cubic centimeter and the mass exceeded 750 milligrams per cubic meter. The number concentration is more than five orders of magnitude higher than a typical ambient level concentration, and the mass concentration is more than four orders of magnitude higher. It is important to indicate, however, that if the engine power rating is lowered by 35 percent from its designated level, both particle mass and number emissions will be reduced by two orders of magnitude. By measuring total and solid particle size and number concentration of particles, one can calculate other metrics such as surface area and mass to provide detail information about particle emissions. Such information can serve as an important database where all metrics of particle emissions are captured.

Commentary by Dr. Valentin Fuster
2006;():17-23. doi:10.1115/ICEF2006-1538.

Reducing particulate emissions from diesel engines has become a major challenge for regions of Europe, Japan and the United States. Many mobile applications have been successfully addressed with passively regenerating wall flow filters. However stationary engines, locomotives and other large constant speed engines often require a different approach to particulate filtration. Flow-through filter technologies have merit for these applications due to their low maintenance requirements, tolerance to misfueling and suitability for engines with high specific PM emissions. When considering the application of a particulate filter to any diesel engine the means of regeneration, or combustion of the accumulated soot, is of critical importance. In the case of filters which are regenerated through the use of a catalytic coating the duty cycle of the engine, and characteristics of the exhaust gas itself dictate the potential success or failure of the system. In many cases interruption of operation, whether due to insufficient regeneration rates, or for scheduled service to remove accumulated ash, is relatively more difficult to accept for locomotive and non-mobile engine operations. Locomotives, power generators and the like often accumulate large number of service hours between scheduled maintenance events and perform tasks where interruption of service can have costly consequences. Details of an investigation into the suitability of a flow-through filter for heavy-duty constant speed engines are presented. Aspects of the design, including materials selection, catalyst coating and performance under various conditions are discussed. Results from CFD and micro-dilution tunnel particulate sampling of full-scale devices support the progressive refinement of the design.

Commentary by Dr. Valentin Fuster
2006;():25-29. doi:10.1115/ICEF2006-1548.

It is well known that water can be used to prevent NOx formation during a combustion process. It is based on the principle by decreasing flame temperature with increasing the specific heat capacity of combustion air by adding water to a combustion chamber. Introducing water into a charge air enables much more water addition into a combustion chamber than other methods, which can reduce NOx emission to lower level than the others. The method has also the advantage of low installation cost. In a general water injection system for a charge air only hot water is sprayed into the charge air and vaporized, but more effective means to introduce water into the charge air is needed because only small amount of water is evaporated in hot water injection system. In this study, steam and hot moisturizing water are injected simultaneously. The steam supplies steady additional energy for evaporation of the water and can be vapor by itself. The new method was evaluated for NOx reduction performance on a medium speed diesel engine. NOx emission was reduced to 10∼38% on the 27∼59gram water per kilogram dry air.

Commentary by Dr. Valentin Fuster

Fuels and Combustion

2006;():31-46. doi:10.1115/ICEF2006-1508.

The use of exhaust gas recirculation (EGR) for a spark-ignition engine was examined using a thermodynamic cycle simulation including the second law of thermodynamics. Both a cooled and an adiabatic EGR configuration were considered. The engine was a 5.7 liter, automotive engine operating from idle to wide open throttle, and up to 6000 rpm. First, the reduction of nitric oxides is quantified for the base case condition (bmep = 325 kPa, 1400 rpm, φ = 1.0 and MBT timing). Over 90% reduction of nitric oxides is obtained with about 18% EGR for the cooled configuration, and with about 26% EGR for the adiabatic configuration. For constant load and speed, the thermal efficiencies increase with increasing EGR for both configurations, and the results show that this increase is mainly due to decreasing pumping losses and decreasing heat losses. In addition, results from the second law of thermodynamics indicated an increase in the destruction of availability (exergy) during the combustion process as EGR levels increase for both configurations. The major reason for this increase in the destruction of availability was the decrease in the combustion temperatures. Complete results for the availability destruction are provided for both configurations.

Commentary by Dr. Valentin Fuster
2006;():47-66. doi:10.1115/ICEF2006-1509.

The use of either hydrogen or isooctane for a spark-ignition engine was examined using a thermodynamic cycle simulation including the second law of thermodynamics. The engine studied was a 5.7 liter, automotive engine operating from idle to wide open throttle. The hydrogen or isooctane was assumed premixed with the air. Two features of hydrogen combustion that were included in the study were the higher flame speeds (shorter burn durations) and the wider lean flammability limits (lean equivalence ratios). Three cases were considered for the use of hydrogen: (1) standard burn duration and an equivalence ratio of 1.0, (2) a shorter burn duration and an equivalence ratio of 1.0, and (3) a shorter burn duration and variable, lean equivalence ratios. The results included thermal efficiencies, other performance metrics, second law parameters, and nitric oxide emissions. In general, for the cases with an equivalence of 1.0, the brake thermal efficiency was slightly lower for the hydrogen cases due to the higher temperatures and higher heat losses. For the variable, lean equivalence ratio cases, the thermal efficiency was higher for the hydrogen case relative to the isooctane case. Due to the higher temperatures, the hydrogen cases had over 50% higher nitric oxide emissions compared to the isooctane case at the base conditions. In addition, the second law analyses indicated that the destruction of availability during the combustion process was lower for the base hydrogen case (11.2%) relative to the isooctane case (21.1%).

Commentary by Dr. Valentin Fuster
2006;():67-75. doi:10.1115/ICEF2006-1512.

The purpose of this study is to investigate the effect of injection parameters on the injection and spray characteristics of dimethyl ether and diesel fuel. In order to analyze the injection and spray characteristics of dimethyl ether and diesel fuel with employing high-pressure common-rail injection system, the injection characteristics such as injection delay, injection duration, and injection rate, spray cone angle and spray tip penetration was investigated by using the injection rate measuring system and the spray visualization system. In this work, the experiments of injection rate and spray visualization are performed at various injection parameters. It was found that injection quantity was decreased with the increase of injection pressure at the same energizing duration and injection pressure In the case of injection characteristics, dimethyl ether showed shorter of injection delay, longer injection duration and lower injected mass flow rate than diesel fuel in accordance with various energizing durations and injection pressures. Also, spray development of dimethyl ether had larger spray cone angle than that of diesel fuel at various injection pressures. Spray tip penetration was almost same development and tendency regardless of injection angles.

Topics: Fuels , Sprays
Commentary by Dr. Valentin Fuster
2006;():77-86. doi:10.1115/ICEF2006-1516.

When a fuel spray impinges on an interior surface of an engine, a thin liquid film can form. The relatively slow evaporation of the film has been shown to be a cause of increased pollutant emissions and reduced engine performance. To improve the understanding of how fuel films affect engine emissions and performance, a research program was initiated to study the physical processes involved in the evaporation of films composed of mixtures of hydrocarbons. The specific goal of the research reported here is to develop a method of simultaneously measuring the mass and composition of evaporating films. This method enables one to compute the evaporation rate of each component in the film. To our knowledge, these composition measurements are the first direct, time-resolved measurements of the changing composition of an evaporating liquid film composed of multiple volatile components. Mass and composition of evaporating liquid films were measured quantitatively using a Fourier transform infrared spectrometer (FT-IR). Evaporation rates for pure solvents and mixtures were determined through a calibration of the FT-IR measurements and these results were validated by measurements acquired with an analytical balance. The FT-IR also measured compositional changes for bi-component mixtures during the evaporation process. Three of the hydrocarbon solvents studied were hexane, cyclohexane, and 3-methylpentane. These were chosen for their similarities in molecular weight and physical properties as well as their comparatively unique infrared absorption spectra. Isooctane was also used because of its prevalence as a gasoline substitute in many engine studies and because of its slow evaporation rate compared to the smaller hydrocarbons. Solvents were studied individually and in various mixtures. Based on these preliminary results the method developed here is expected to be an important tool for studying the transport processes in an evaporating film.

Topics: Fuels , Evaporation
Commentary by Dr. Valentin Fuster
2006;():87-96. doi:10.1115/ICEF2006-1518.

In this paper a comparative investigation between two different injectors for Common Rail diesel apparatus has been carried out in terms of transient response and spray pattern for different injection strategies. Performances of an innovative Magneti Marelli (MM) gasoline derived injector have been evaluated against the Bosch generation injectors for multiple strategies. Both injectors have operated on an automotive apparatus controlled by a Programmable Electronic Control Unit to set injection strategies in terms of pulses number, duration and dwell time. The working mode of the two injectors is completely different: the Bosch injector is activated by the inner fuel hydraulic circuit while the Magneti Marelli one operates a direct control of the needle lift through the solenoid currents. The Bosch nozzle characteristics are 5 holes, 150° spray angle, and 0,13 mm diameter. The MM injector main characteristics are low hydraulic losses, simple component structure and ready use of the fuel at the nozzle opening being able to control small fuel flow rates (0.1 mg/str) in the injection pressures range 20–70 MPa. The geometry of the nozzle is quite similar to the Bosch one being a 5 hole, 150° spray angle, 0.12 mm diameter. Single, pilot+main and pilot+split main strategies have been explored for the two injectors at 50 and 60 MPa injection pressures investigating the spray behavior for two amounts of injected fuel (5.0 and 6.5 mg/str). The systems have been characterized in terms of injected fuel rate as well spatial and temporal behavior of the emerging jets from the nozzle. Images of the spray have been collected by a synchronized CCD camera at different time from the start of injection. The jets have evolved in an optically accessible high pressure vessel at ambient temperature as well in an optically accessible single-cylinder 2-stroke Diesel engine extracting the fuel spray parameters from the collected images applying a digital processing techniques. Due to the diverse mechanism of the injector actuation, a different temporal and spatial fuel distribution has been registered for the two apparatuses. These could strongly influence the air/fuel mixture formation and combustion process with effect on the emissions. Preliminary engine tests performed on a light duty direct injection diesel engine, equipped with the MM injector, have highlighted the potential of the MM injector to handle acceptable engine performances.

Commentary by Dr. Valentin Fuster
2006;():97-107. doi:10.1115/ICEF2006-1521.

The basic physical law governing the injection in Common Rail Systems is the compressibility of the fuel. The effects of pressure wave dynamics, the layout of the system volume and its geometrical distribution strongly affect the injection events at every injector. In this Paper, three different arrangements of system volumes and their effect upon the performance of the individual injectors are compared using the hydraulics simulation tool AMESim. Two systems are known in the passenger car and the heavy duty diesel engine domains. The third system is new and takes advantage of pressure wave dynamics to tailor the injection event. This system is best suited for Diesel Engines with a power from 1 to 5 MW, as used in locomotives, ships, power generation and heavy earthmoving machinery. It produces a more favorable pattern of the injection pressure and injection rate shape during any injection event by hydraulically interconnecting the individual injector’s accumulators during the injection and taking advantage of pressure wave dynamics. Right after the end of each injection, dynamic pressure pulsations are evened out with a dampening device. A multi-cylinder system provides equal conditions for all injections. Its very simple design and increased performance makes the novel system of very attractive use in the above mentioned fields.

Commentary by Dr. Valentin Fuster
2006;():109-115. doi:10.1115/ICEF2006-1539.

Biodiesel is a nontoxic, biodegradable, and renewable fuel which can be made from vegetable oils. Most biodiesel used today is blended with petroleum diesel because lower level blends can be used in compression-ignition engines designed for conventional diesel fuel. Blending biodiesel with petroleum based diesel affects the physical properties of the fuel, which can have an impact on the performance of the engine. If the percentage of biodiesel in the fuel tank can be measured easily, it is possible to make engine adjustments to enhance the performance and emissions. In this project, a commercial fuel sensor was evaluated as a possible biodiesel percentage sensor. The Ford flexible fuel sensor was originally designed to measure the amount of ethanol in ethanol/gasoline blends. This resonant electromagnetic cavity sensor was used to determine the correlation between the output frequency and the percentage of biodiesel in blends of soybean oil biodiesel and No. 2 diesel fuel. Pure diesel fuel and soybean B100 were tested to serve as reference points. Soybean B100 from a different distributor and canola B100 were tested to investigate the effect of different biodiesel sources and types on output frequency. The output frequency of vegetable oil was also measured in order to consider the effect of using vegetable oil instead of biodiesel when trying to estimate blend percentage. The Ford flexible fuel sensor was capable of measuring the biodiesel percentage to within about ± 3%, and temperature changes between 10 and 50 °C produced no substantial change in this measurement. Emissions and performance measurements on a production diesel engine suggest that this sensor accuracy is sufficient to provide feedback for making adjustments to the engine operation.

Topics: Sensors , Fuels , Biodiesel
Commentary by Dr. Valentin Fuster
2006;():117-126. doi:10.1115/ICEF2006-1543.

Homogenous Charge Compression Ignition (HCCI) is a mode of combustion in IC engines in which premixed fuel and air is ignited spontaneously. There is a belief that there is a great potential to improve fuel consumption and reduce NOx emissions using HCCI. In this study, a single zone, zero dimensional, thermo-kinetic model has been developed and a computer program with MATLAB software is used to predict engine performance characteristics. This model has been used to predict the principal parameters of controlling auto-ignition to acceptable level and this work leads to achieving the working region with two limitations for knock and misfire. The cycle is simulated with premixed blend of methane and DME with air. To highlight the importance of using HCCI engines instead of conventional diesel engines, an ISO continuous operation cycle (COP) and prime power cycle (PRP) has been investigated. Also NOx level are compared in a diesel engine working as a conventional diesel and in HCCI mode.

Commentary by Dr. Valentin Fuster
2006;():127-137. doi:10.1115/ICEF2006-1551.

Two key challenges facing natural gas engines used for cogeneration are spark plug life and high NOx emissions. Using Hydrogen Assisted Lean Operation (HALO), these two key issues are simultaneously addressed. HALO operation, as demonstrated in this project, allows stable engine operation to be achieved at ultra-lean conditions and significantly reduces NOx production. For example, at 8% hydrogen supplementation by energy based upon lower heating values, NOx values of 10 ppm (0.07 g/bhp-hr NOx ) at an exhaust O2 level of 10% were demonstrated, which is a 98% NOx emissions reduction compared to the leanest operating condition achievable without hydrogen. Spark ignition energy reduction (which will increase ignition system life) was successfully achieved using hydrogen at an exhaust O2 level of 9%, leading to a NOx emission level of 28 ppm (0.13 g/bhp-hr NOx ). At this operating condition, it was found that spark energy could be reduced 22% (from 151 mJ supplied to the coil) with 13% hydrogen supplementation based on lower heating values, and even further reduced 27% with 17% hydrogen supplementation, with no reportable effect on NOx emissions for these conditions and with stable engine torque output. Another important result is that the combustion duration was shown to be primarily dependant on hydrogen supplementation, not a function of ignition energy (until the ignitability limit was reached). The next logical step leading from these results is to see how much the spark energy reduction translates into increase in spark plug life by performing durability testing.

Commentary by Dr. Valentin Fuster
2006;():139-145. doi:10.1115/ICEF2006-1552.

A Cooperative Fuels Research (CFR) gasoline engine has been modified to run on computer controlled Port Fuel Injection (PFI) and electronic ignition. Additionally a fast acting sampling valve (controlled by the engine control computer) has been placed in the engine’s intake system between the fuel injector and cylinder head in order to measure the fuel components that are vaporizing in the intake port immediately after the fuel injection event, and separately during the intake valve open period. This is accomplished by fast sampling a small portion of the intake port gases during a specified portion of the engine cycle which are then analyzed with a gas chromatograph. Experimental mixture preparation results as a function of inlet port temperature and pressure are presented. As the inlet port operates at higher temperatures and lower manifold pressures more of the injected fuels’ heavier components evolve into the vapor form immediately after fuel injection. The post-fuel injection fuel-air equivalence ratio in the intake port is characterized. The role of the fuel injection event is to produce from 1/4 to slightly over 1/2 of the combustible fuel-air mixture needed by the engine, as a function of port temperature. Fuel vapor sampling during the intake valve open period suggests that very little fuel is vaporizing from the intake port puddle below the fuel injector. In-cylinder fuel vapor sampling shows that significant fuel vapor generation must occur in the lower intake port and intake valve region.

Topics: Fuels , Engines , Gasoline
Commentary by Dr. Valentin Fuster
2006;():147-163. doi:10.1115/ICEF2006-1553.

High-speed imaging combined with the optical access provided by a research engine offer the ability to directly image and compare ignition and combustion phenomena of various fuels. Such data provide valuable insight into the physical and chemical mechanisms important in each system. In this study, crank-angle resolved imaging data were used to investigate homogeneous charge compression ignition (HCCI) operation of a single-cylinder four-valve optical engine fueled using gasoline, indolene, and iso-octane. Lean operating limits were the focus of the study with the primary objective of identifying different modes of reaction front initiation and propagation for each fuel. HCCI combustion was initiated and maintained over a range of lean conditions for various fuels, from φ = 0.77 to 0.27. The time-resolved imaging and pressure data show high rates of heat release in HCCI combustion correlate temporally to simultaneous, intense volumetric blue emission. Lower rates of heat release are characteristic of spatially-resolved blue emission. Gasoline supported leaner HCCI operation than indolene. Iso-octane showed a dramatic transition into misfire. Similar regions of preferential ignition were identified for each of the fuels considered using the imaging data.

Commentary by Dr. Valentin Fuster
2006;():165-176. doi:10.1115/ICEF2006-1556.

A model for the analysis of diesel engine common rail injection system has been developed and the influence that different fuels have on the injection performances has been investigated. Diesel fuel, biodiesel and kerosene have been used and the differences of injection flow rate, injection pressure time trace, nozzle flow features and break up mechanism have been highlighted. The coupling of two different codes has been used in the simulations: the former one, AMESim code, has been adopted to model the common rail system and to investigate the fuel flow rate and the injection pressure dependence on the fuel type. The latter computational tool, FIRE code, has been initialized by means of the results obtained from the injection system simulation and has been used to perform the 3D investigation of the internal nozzle flow and of the spray formation phenomena, aimed at evaluating the effect of physical fuel features on local flow characteristics and their influence on the system performances. Details of the adopted modeling strategy are described and results of each simulation step are presented.

Commentary by Dr. Valentin Fuster
2006;():177-185. doi:10.1115/ICEF2006-1558.

An investigation of Diesel Particulate Filter (DPF) is performed to obtain deeper insight into the soot loading process. Previous paper has been devoted to the realization of a numerical model to analyse how diesel soot is deposited on the walls of a commercial filter media and to understand the influence of different engine operating conditions on the soot layer growth. The results have been validated by means of experimental data. This paper concerns with the parametrization of particulate deposition profiles and focuses on how soot profile evolves during engine operation in a specified duty cycle, starting from pre-loaded channels. Results of 3D CFD simulations are presented, in which different engine running histories are analyzed.

Topics: Engines , Cycles , Soot
Commentary by Dr. Valentin Fuster
2006;():187-197. doi:10.1115/ICEF2006-1562.

Homogeneous Charge Compression Ignition (HCCI) is an advanced combustion technology being considered for internal combustion engines due to the potential for high fuel conversion efficiency and extremely low PM and NOx emissions. In principle, HCCI involves the auto-ignition of a homogeneous mixture of fuel, air and diluents at low to moderate temperatures and high pressure. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This paper reports the preliminary results of an experimental and modeling study of HCCI engine operation using n-heptane, which has a well known fuel chemistry. The experiments were designed to explore the effects of intake temperature, compression ratio, air/fuel ratio, engine speed and turbo-charging on HCCI combustion. A numerical model with detailed fuel chemistry was developed to simulate the combustion process in HCCI engines and predict engine performance. The model captured the main combustion stage and its variation in phasing with critical engine parameters.

Commentary by Dr. Valentin Fuster
2006;():199-208. doi:10.1115/ICEF2006-1563.

Autoignition in SI engines is an abnormal combustion mode and may lead to engine knock in SI engines. Knock may cause damage and it is a source of noise in engines. It limits the compression ratio of the engine and a low compression ratio means low fuel conversion efficiency of the engine. In this paper a multi zone model based on an existing two zone model Hajireza et al., [1 and 12] and Stenlåås et al., [30] is developed and validated against the experimental results. The validation is done by using the same detailed chemical mechanism consisting of 141 species and about 1405 reactions under the same conditions. The model is a zero dimensional model capable of simulating a full engine cycle. The two zone combustion model consists of a burned and an unburned zone, separated by a thin adiabatic flame front. The multi zone model differs in the handling of the burned gas. In the multi zone case a number of burned zones are present. The number of zones is decided by the temperature difference between the flame front and the last generated burned zone. The detailed chemical mechanism is taken into account in each zone, while the propagating flame front is calculated from the Wiebe function. Each zone is assumed to be a homogeneous mixture with a uniform temperature, mole and mass fractions of species. The spatial variation of the pressure is neglected, i.e., it is assumed to be the same in the whole combustion chamber at every instant of time. Autoignition is handled by the chemical kinetic model. As the unburned zone is assumed homogeneous the effect of auto ignition is a single pressure peak. The model is not designed to predict the pressure oscillations seen in engine knock.

Commentary by Dr. Valentin Fuster
2006;():209-218. doi:10.1115/ICEF2006-1564.

The effects of the introduction of the gaseous fuels, methane, hydrogen and carbon monoxide into the intake of a variable compression ratio n-heptane fuelled HCCI, CFR engine were investigated. The variations in some of the key combustion and operational parameters were determined experimentally. These included cylinder pressure and its rise rate temporal developments, autoignition timing, combustion durations for both the low and high temperature reaction regions, COV values for IMEP and maximum cylinder pressure, and the incidence of knock and its intensity. In parallel with the experimental investigation, results of a numerical simulation of the processes involved obtained by employing a KIVA based approach while incorporating sufficiently detailed chemical kinetics are presented. It was found that supplementing n-heptane HCCI with gaseous fuels could inhibit the low temperature combustion region and delay to varying extents the high temperature combustion region. Methane admission produced lengthening of the delay to autoignition and extended the combustion durations. It is suggested that supplementing the liquid fuel with methane may be a means for controlling the combustion process of a liquid fuelled HCCI engine while obtaining higher power and acceptable levels of emissions without producing unacceptably heavy knock. However, the addition of hydrogen or carbon monoxide could not reduce the intensity of knock while improving power output.

Commentary by Dr. Valentin Fuster
2006;():219-224. doi:10.1115/ICEF2006-1573.

In the present work, the combustion, performance and emission characteristics of sunflower oil, sunflower methyl ester and its blends were studied and compared with diesel by employing them as fuel in a single cylinder, direct injection, 4.4 KW, air cooled diesel engine. Emission measurements were carried out using five-gas exhaust gas analyzer and smoke meter. The performance characteristics of Sunflower oil, Sunflower methyl ester and its blends were comparable with those of diesel. The components of exhaust such as HC, CO, NOx and soot concentration of the fuels were measured and presented as a function of load and it was observed that the blends had similar performance and emission characteristics as those of diesel. NOx emissions of sunflower oil methyl ester were slightly higher than that of diesel but that of sunflower oil was slightly lower than that of diesel. With respect to the combustion characteristics it was found that the biofuels have lower ignition delay than diesel. The heat release rate was very high for diesel than for the biofuel.

Commentary by Dr. Valentin Fuster
2006;():225-232. doi:10.1115/ICEF2006-1582.

This paper emphasizes on the effects of different biodiesels and diesel on; heat release, ignition delay, endothermic and exothermic reactions, NOx, fuel injection pressure due to the fuel’s modulus of elasticity and cylinder pressure. Two 100% biodiesel and its blends of 20% with of low sulfur #2 diesel, and #2 diesel are tested on a single cylinder diesel engine under full load condition. Engine performance and emissions data is obtained for 100% and 20% biodiesels blends and #2 diesel. Testes were conducted at Engine Systems Development Centre, Inc. (ESDC) to evaluate the effects of biodiesel and its blends on the performance and emissions of a single-cylinder medium-speed diesel engine. The main objective of this work was to gain initial information and experience about biodiesel for railway application based on which biodiesel and its blends could be recommended for further investigation on actual locomotives.

Topics: Heat , Biodiesel
Commentary by Dr. Valentin Fuster
2006;():233-244. doi:10.1115/ICEF2006-1586.

An extension to a phenomenological sub-model for soot formation to include soot agglomeration effects is developed. The improved sub-model, consisting of six coupled differential equations, was incorporated into a commercial CFD code and used to investigate soot formation in a heavy-duty diesel engine. The results of the numerical simulation show that the soot oxidation process is reduced close to the combustion chamber walls. This is due to the lower charge temperatures encountered as a result of heat transfer to the combustion chamber walls. The sub-model predicts that larger soot particles and clusters are encountered in the annular region close to the combustion chamber walls at the end of the combustion cycle. These results are consistent with available in-cylinder experimental data on soot.

Commentary by Dr. Valentin Fuster
2006;():245-251. doi:10.1115/ICEF2006-1588.

Sulfur free synthetic diesel fuels can be produced using gas to liquids (GTL) technology, and may prove useful as a substitute for conventional diesel fuels when oil reserves are depleted. With non-detectable amounts of sulfur and aromatics, these fuels should generate lower emissions and enable catalytic clean up. This paper presents the results of a durability test conducted on a Detroit Diesel Series 50 diesel engine-generator operating on two synthetic GTL diesel fuels. Besides providing a comparison of diesel emissions, the paper also provides a comparison of generator fuel efficiency and brake specific fuel consumption between the synthetic fuels and conventional diesel. Documented emissions include total hydrocarbons (THC), carbon monoxide (CO) and oxides of nitrogen (NOx ). All tests on the diesel engine reported were conducted at the factory set injection timing. As the best performance of an engine on a particular fuel may be affected by injection timing, further tests of the synthetic fuels at different injection timings are needed and will be discussed in future work.

Commentary by Dr. Valentin Fuster

ARES/ARICE Symposium

2006;():253-258. doi:10.1115/ICEF2006-1510.

Waukesha Engine has developed an advanced power generation engine using technologies that were developed as part of the Department of Energy-Advanced Reciprocating Engine Systems (ARES) program. The engine uses lean-burn technologies for high efficiency, and low NOx emissions. The technical goals for the ARES program were 50% Brake Thermal Efficiency (BTE) and 0.075 g/kW-hr NOx emissions (with aftertreatment). The goals for the Waukesha Engine Phase 1 Advanced Power Generation (APG) engine are 42% Brake Thermal Efficiency (BTE) and 0.75 g/kW-hr (1.0 g/Bhp-hr) NOx emissions, capable of 0.075 g/kW-hr (0.1 g/Bhp-hr) with aftertreatment. The barriers and technical paths applied to achieve this performance are discussed in this paper.

Commentary by Dr. Valentin Fuster
2006;():259-265. doi:10.1115/ICEF2006-1517.

Waukesha Engine, in cooperation with the Department of Energy, has designed a new high efficiency natural gas engine designed specifically for the power generation market. The APG1000 (Advance Power Generation) engine is capable of achieving 1 MW output at 42% thermal efficiency and less than 1 g/bhp-hr Nox. A design method using modern tools such as 3-D modeling, rapid prototyping and computer simulation have, in a large part, contributed to the success of this engine. This paper discusses the methodology and tools used in the design of the APG engine.

Topics: Engines , Design
Commentary by Dr. Valentin Fuster
2006;():267-279. doi:10.1115/ICEF2006-1525.

Well-designed surface texturing may be used to reduce ring/liner friction and increase efficiency in internal combustion engines. This study investigated the effects of textures of either grooves or dimples on ring/liner friction, in the hydrodynamic and mixed regimes. Existing MIT models were used to conduct this research. The ring-pack model is based on averaged flow-factor Reynolds analysis, and is used in conjunction with a deterministic model for flow factor calculation. Although this advanced model is applicable in a wide range of cases, the surface textures studied here are very different than a typical liner surface, and can be represented only approximately by the averaged analysis upon which the ring simulation is based. For this reason, this analysis of surface features has focused on a parametric study, the goal of which is to analyze trends relating ring/liner friction to surface parameters, and to make a general evaluation of the potential of surface texturing to reduce ring-pack losses. In the hydrodynamic and mixed regimes, surface texturing affects the fluid pressure in the lubricant between ring and liner, thus affecting the ability of the oil film to support the ring load. If the effect of the texturing is to impede the flow of lubricant, the result will be an increase in oil film thickness. This causes friction reduction in two ways: if asperity contact was present, it is reduced; and the increase in film thickness causes a decrease in shear rate, thus decreasing oil shear stress. It was found that surfaces with both dimpled and grooved textures could cause friction reduction through this mechanism, with deeper features and more transverse groove patterns causing the greatest reduction. Friction also decreased with increasing area ratio (the percentage of the surface that is occupied by the surface features) for both grooves and dimples, and was only slightly dependent on groove width and dimple diameter. Because the effect of the surface texturing is on hydrodynamic effects in the oil, it is strongly coupled with lubricant properties. If surface texturing and lubricant viscosity are optimized together side effects such as oil consumption and wear can be mitigated, while friction can be reduced even further than it is via surface texturing alone. This possibility was also briefly considered in this study.

Commentary by Dr. Valentin Fuster
2006;():281-293. doi:10.1115/ICEF2006-1526.

The piston ring-pack contributes a large portion of the mechanical losses in an internal combustion engine. In this study, the effects of lubricant viscosity are evaluated with the goal of reducing these mechanical losses. Oil viscosity affects friction directly in the hydrodynamic regime, where hydrodynamic friction increases with viscosity. It also influences boundary friction indirectly via oil film thickness — higher viscosity causes oil films to be thicker, which reduces asperity contact. At the optimum viscosity (the viscosity at which minimum friction losses are incurred) there is a balance between these hydrodynamic and boundary effects. As piston speed, ring loading, and other parameters change during the engine cycle, the optimum oil viscosity also changes. If the variation of viscosity could be controlled during the cycle, it could be maintained at an optimum at all times. In this study, several theoretical and realistic cases were studied to quantify the friction benefit that could be obtained if this were possible. Idealized cases with low viscosity near mid-stroke (to reduce hydrodynamic friction) and high viscosity near end-strokes (to reduce boundary contact) were considered, as were several more realistic cases based on temperature and shear-rate dependencies. It was found that, for the oil control ring studied, the effect on friction of keeping viscosity high near end-strokes is very small, and does not provide a substantial benefit (in terms of friction) over allowing viscosity to vary naturally with temperature and shear rate. Two mechanisms lead to the relatively small size of the friction benefit: the contribution to total cycle ring friction from the dead-center area is small, because of low piston speeds there; and any reduction in asperity contact due to increased viscosity is accompanied by an increase in hydrodynamic friction, which cancels out some of the benefit. Oil viscosity near mid-stroke, where most of the ring/liner friction is generated, is the dominant viscosity that controls the overall friction losses for the ring. Although its contribution to friction reduction is not large, maintaining high lubricant viscosity near dead-centers can lead to a reduction in wear in that region, because asperity contact decreases. For the ring-pack studied, a friction reduction of ∼7% is predicted when viscosity is reduced in the mid-stroke region (based on OCR effects alone). If end-stroke viscosity is also kept high, the end-stroke regions, where current engines experience the most wear, will see a reduction in asperity contact (although there will still be a slight wear increase in the mid-stroke). An end-stroke wear reduction of up to 25% is predicted by the current model.

Commentary by Dr. Valentin Fuster
2006;():295-305. doi:10.1115/ICEF2006-1535.

Lean NOx trap catalysts have demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as “regeneration” since the catalyst is reactivated for more NOx trapping after NOx purge. Creating the rich exhaust conditions for regeneration can be accomplished by catalytic partial oxidation of methane in the exhaust system. Furthermore, catalytic reforming of partial oxidation exhaust can enable increased quantities of H2 which is an excellent reductant for lean NOx trap regeneration. It is critical to maintain clean and efficient partial oxidation and reforming processes to keep the lean NOx trap functioning properly and to reduce extra fuel consumption from the regeneration process. Although most exhaust constituents do not impede partial oxidation and reforming, some exhaust constituents may negatively affect the catalysts and result in loss of catalytic efficiency. Of particular concern are common catalyst poisons sulfur, zinc, and phosphorous. These poisons form in the exhaust through combustion of fuel and oil, and although they are present at low concentrations, they can accumulate to significant levels over the life of an engine system. In the work presented here, the effects of sulfur on the partial oxidation and reforming catalytic processes were studied to determine any durability limitations on the production of reductants for lean NOx trap catalyst regeneration.

Commentary by Dr. Valentin Fuster
2006;():307-315. doi:10.1115/ICEF2006-1542.

A model for a possible system to implement Selective NOx Recirculation (SNR) technology for stationary lean-burn natural gas engines was developed. SNR is a NOx (NOx includes the various oxides of nitrogen found in an exhaust stream) removal after-treatment technology with four phases; cooling the hot exhaust gas, NOx adsorption onto a sorbent material, periodic NOx desorption using heat, and NOx decomposition within the combustion process. This paper presents the model, summarizes the research used to develop the model, and presents model output. NOx decomposition in the combustion process was investigated by injecting nitric oxide (NO) into the intake of a Cummins L10G natural gas fueled spark-ignited engine (210 kW at 2100 rpm). Experimental campaigns were conducted during lean-burn and rich-burn operation to quantify in-cylinder NOx decomposition. Data previously published suggest that rich burn is essential for adequate NOx decomposition and that lean burn was ineffective. The NOx adsorption/desorption characteristics of the sorbent material were quantified using a bench top adsorption system equipped with four thermocouples, an in-line heater, a mass flow controller and a Rosemont Analytical NOx analyzer. The sorbent chamber was filled with activated carbon sorbent material. Extensive testing of the adsorption characteristics using 500 ppm NO (balance nitrogen) from a pressure tank yielded a mass percent of .0005 NO to carbon. These results suggested that unacceptably large adsorbers would be needed in industrial applications. However, further measurement using real exhaust showed a loading of 0.65 mass percent of NO to carbon. The presence of oxygen and water are implicated in this improved adsorption. This scaled system considered the heating rates (for desorption) and cooling rates (for adsorption) for the bed at the time when desorption and adsorption processes were initiated. An adsorption/desorption model that considered gas temperature and heat and mass transfer was formulated based on these data. A simplified linear driving force model was developed to predict NOx adsorption into the sorbent material as cooled exhaust passed over fresh sorbent material.

Commentary by Dr. Valentin Fuster
2006;():317-325. doi:10.1115/ICEF2006-1574.

Past research has shown that laser ignition is capable of operating high bmep engines at high efficiency and with low emission levels. However, for laser ignition systems to be adopted by industry, one requires a practical (and economical) mode of beam delivery other than the conventional open-path beam delivery that has been used in much of the past research. One potential beam delivery method is via optical fibers capable of handling high peak power. This paper summarizes our recent efforts in this area. Using coated hollow fibers, our research group has demonstrated the delivery of laser pulses to form optical sparks both on the bench-top and for ignition and operation of a single cylinder of an ARES engine. When held relatively straight, the hollow fibers allow transmission of nanosecond pulse energies of 10s of milli-Joules with transmission above 90% and sufficient beam quality for spark formation. We have also been able to deliver optical sparks on the bench-top with high peak power pulsed fiber lasers. Pulse energies in those experiments were approximately 2 mJ. Other recent work has studied the transmission characteristics of recently developed photonic crystal fibers.

Commentary by Dr. Valentin Fuster
2006;():327-347. doi:10.1115/ICEF2006-1578.

A demonstration system has been developed intending to meet the California Energy Commission’s primary goal of improving California’s electric energy cost/value by providing a low-cost, high-efficiency distributed power generation system that operates on landfill gas as fuel. The project team led by Makel Engineering, Inc. includes UC Berkeley, CSU Chico and the Butte County Public Works Department. The team has developed a reliable, multi-cylinder Homogeneous Charge Compression Ignition (HCCI) engine by converting a Caterpillar 3116, 6.6 liter diesel engine to operate in HCCI mode. This engine utilizes a simple and robust thermal control system. Typically, HCCI engines are based on standard diesel engine designs with reduced complexity and cost based on the well known principles of engine dynamics. Coupled to an induction generator, this HCCI genset allows for simplified power grid connection. Testing with this HCCI genset allowed for the development of a control system to maintain optimal the inlet temperature and equivalence ratio. A brake thermal efficiency of 35.0% was achieved while producing less than 10.0 ppm of NOx and 30 kW of electrical power. Less than 5.0 ppm of NOx was recorded with a slightly lower brake thermal efficiency. Tests were conducted with both natural gas and simulated landfill gas as a fuel source. This demonstration system has shown that landfill gas fueled Homogeneous Charge Compression Ignition engine technology is a viable technology for distributed power generation.

Commentary by Dr. Valentin Fuster

Engine Design for High Efficiency and Low Emissions

2006;():349-358. doi:10.1115/ICEF2006-1506.

In order to comply with current emissions regulations, a detailed analysis of the combustion and emission formation processes in the Diesel engines accounting for the effect of the main operating parameters is required. The present study is based both on 0D and 3D numerical simulations by compiling 0D chemical kinetics calculations for Diesel oil surrogate combustion and emission (soot, NOx) formation mechanisms to construct a φ-T (equivalence ratio - temperature) parametric map. In this map, the regions of emissions formation are depicted defining a possible optimal path between the regions by placing on the same map the engine operation conditions represented by the computational cells, whose parameters (equivalence ratio and temperature) are calculated by means of 3D engine modelling. Unlike previous approaches based on static parametric φ-T maps to analyze different combustion regimes and emission formations in Diesel engines, the present paper focuses on a construction of dynamic φ-T maps, in which the pressures and the elapsed times were taken in compliance with those calculated in the 3D engine simulations. The 0D chemical kinetics calculations have been performed by the SENKIN code of the Chemkin-2 library. In-cylinder conditions represented by computational cells with known φ and T are predicted using KIVA-3V code. When cells are plotted on the map, they identify the trajectories helping to navigate between the emissions regions by varying hardware and injection parameters. Sub-models of the KIVA-3V, rel. 2 code has been modified including spray atomization, droplet collision and evaporation, accounting for multi-component fuel vapor coupled with the improved versions of the chemistry/turbulence interaction model and new formulation of the combustion kinetics for the diesel oil surrogate (consisting in 70 species participating in 310 reactions). Simulations were performed for the HSDI 1.300 Fiat Diesel engine at optimized engine operating conditions and pilot injections. Finally, numerical results are compared with the experimental data on in-cylinder pressure, Rate of Heat Release, RoHR, and selected species distributions.

Commentary by Dr. Valentin Fuster
2006;():359-368. doi:10.1115/ICEF2006-1519.

An advanced reciprocating internal combustion engine without a crankshaft and connecting rod mechanisms that the author would like to present is based on another law of physics. The invention titled ‘Nano-Magneto-Rheological Mechatronic Commutator Internal Combustion Engine’, that is concisely termed the Fijalkowski engine by someone, is based on a whole new propulsion engineering solution that has no analogies in the world. Thus, this paper focuses on an advanced reciprocating internal combustion engine termed the Fijalkowski engine, which may utilize a nano-magneto-rheological mechatronic commutator that may replace the crankshaft and connecting rod (conrod) mechanisms. This mechatronic commutator may let nano-magneto-rheological rotary ratchets oscillate in a controlled wobble while keeping the output shaft spinning smoothly; and although opposed pistons and opposed cylinders similar to those in automotive ‘boxer’ engines may power the Fijalkowski engine, it may also utilize opposed cylinders containing four pairs of two end-to-end opposed pistons for higher power densities. The nano-magneto-rheological mechatronic commutator may be utilized to convert between one form of mechanical motion that is linear, reciprocating motion of pistons and another — that is rotary motion of the output shaft.

Commentary by Dr. Valentin Fuster
2006;():369-379. doi:10.1115/ICEF2006-1520.

The paper describes the design process for a controlled pulse turbocharging system (CPT) on a 5 cylinder 4-stroke marine engine and highlights the potential for improved engine performance as well as reduced smoke emissions under steady state and transient operating conditions, as offered by the following technologies: • controlled pulse turbocharging, • high pressure air injection onto the compressor impeller as well as into the air receiver, and • an electronic engine control system, including a hydraulic powered electric actuator. Calibrated engine simulation computer models based on the results of tests performed on the engine in its baseline configuration were used to design the CPT components. Various engine tests with CPT under steady state and transient operating conditions show the engine optimization process and how the above-mentioned technologies benefit engine behavior in both generator and propeller law operation.

Commentary by Dr. Valentin Fuster
2006;():381-392. doi:10.1115/ICEF2006-1522.

As part of the Norfolk-Southern Railroad’s on-going investigation into fuel consumption reductions for their fleet of 3000 locomotives, the Center for Alternative Fuels, Engines and Emissions at West Virginia University conducted on-site locomotive engine performance and emissions measurements to characterize the performance, fuel consumption and emissions associated with fuel injectors from two injector suppliers. Emissions and fuel consumption were measured using the West Virginia University Transportable Locomotive Emissions Testing Laboratory, which was set up at the Norfolk-Southern Heavy Repair Facility in Roanoke, Virginia. The tests were conducted to evaluate potential emissions and fuel consumption differences between two fuel injector suppliers using an EMD GP38-2 locomotive equipped with a 2100 hp (1566 kW), 16-cylinder, EMD 16-645E engine. The test locomotive engine was freshly overhauled and certified to the EPA locomotive Tier 0 emissions standards. Emissions and fuel consumption measurements were conducted according to the Federal Test Procedures defined in the Code of Federal Regulations 40CFR Part 92 Subpart B [1]. The engine was first tested in the “as overhauled” configuration with the OEM fuel injectors to establish the baseline emissions and fuel consumption. The baseline FTP results confirmed that this locomotive was in compliance with the Federal Tier 0 emissions standards. The OEM specification fuel injectors were replaced with “Fuel Saver” injectors designed and manufactured by an aftermarket injector supplier referred to in this paper as Supplier B. The Supplier B injectors reduced fuel consumption on the average of 2–4% for each notch, except for Notch 4 and Low Idle. However, the Supplier B injectors increased the NOx levels by 20–30% for almost every notch, which is an expected result due to the improved combustion efficiency.

Commentary by Dr. Valentin Fuster
2006;():393-404. doi:10.1115/ICEF2006-1529.

It has been demonstrated by previous researchers that an approximate value of the bulk flow velocity through the spark plug gap of a running spark ignition engine may be deduced from the voltage and current waveforms of the spark. The technique has become known as spark anemometry and offers a robust means of velocity sensing for engine combustion chambers and other high temperature environments. This paper describes an experimental study aimed at improving performance of spark anemometry as an engine research tool. Bench tests were conducted using flow provided by a calibrated nozzle apparatus discharging to atmospheric pressure. Whereas earlier studies had relied upon assumptions about the shape of the stretching spark channel to relate the spark voltage to the flow velocity, the actual spark channel shape was documented using high speed video in the present study. A programmable ignition system was used to generate well-controlled constant current discharges. The spark anemometry apparatus was then tested in a light duty automotive engine. Results from the image analysis of the spark channel shape undertaken in the present study have shown that the spark kernel moves at a velocity of less than that of the free stream gas velocity. A lower velocity threshold exists below which there is no response from the spark. It is possible to obtain a consistent, nearly linear relationship between the first derivative of the sustaining voltage of a constant current spark and the free stream velocity if the velocity falls within certain limits. The engine tests revealed a great deal of cycle-to-cycle variation in the in-cylinder velocity measurements. Instances where the spark restrikes occur during the cycle must also be recognized in order to avoid false velocity indications.

Commentary by Dr. Valentin Fuster
2006;():405-412. doi:10.1115/ICEF2006-1545.

Direct fuel injection has become necessary in two-stroke S.I. engines, since it prevents one of the major problems of these engines, that is fuel loss from the exhaust port. Another important problem is combustion irregularity at light loads, due to excessive residual gas in the charge, and can be solved by charge stratification. High-pressure liquid fuel injection is able to control the mixing process inside the cylinder for getting either stratified charge at partial loads or quasi-stoichiometric conditions, as it is required at full load. The feasibility of this solution for a small engine for light motorcycles has been studied using CFD tools. An exhaustive investigation carried out by the KIVA3v code allowed to design a 50 cm3 engine prototype with a satisfactory behaviour even at light loads in unthrottled condition, as proved by good fuel economy and engine stability in dynamometric bench tests. Exhaust gas analysis and indicated pressure behaviour confirm stratification and combustion correctness. For the final part of the research the adoption of the AVL-Fire code has been considered: the possibility to take into account any combustion chamber and transfer duct geometric details and the accuracy of spray breakup and wall film models allow to better understand the engine behaviour throughout the operating range, obtaining useful information in order to efficiently shorten the experimental time required for the EU map-setting.

Commentary by Dr. Valentin Fuster
2006;():413-419. doi:10.1115/ICEF2006-1546.

The centrifugal compressor of marine engine turbocharger is composed of impeller, 1st vaneless diffuser, vaned diffuser, 2nd vaneless diffuser and volute casing. An examination of the condition of the flow leaving the impeller exit kinetic energy often accounts for 30–50% of the shaft work input to the compressor stage, and for energy efficiency it is important to recover as much of this as possible. This is the function of the diffuser which follows the impeller. Effective pressure recovery downstream of an impeller is very important to realize a centrifugal compressor with high efficiency and high pressure ratio, and an appropriate selection of a diffuser for a specific impeller is a critical step to develop the compressor accordingly. The purpose of this study is to investigate the sensitivity of how compressor performances changes as vaned diffuser geometry is varied. Three kinds of vaned diffusers were studied and its results were compared. First vaned diffuser type is based on NACA airfoil and second is channel diffuser and third is conformal transformation of NACA 65 airfoil. Mean-line prediction method was applied to investigate the performance and stability for three kinds of diffusers. And CFD analyses have been done for comparison and detailed interior flow pattern study. In this study, the off design behavior of three different type of diffuser, given by mean-line prediction, was investigated using CFD results and selected best diffuser geometry which satisfy wider operating range and higher pressure recovery than the others. The numerical results were compared with experimental data for validation.

Commentary by Dr. Valentin Fuster
2006;():421-429. doi:10.1115/ICEF2006-1559.

High demands are placed on large gas engines in the areas of performance, fuel consumption and emissions. In order to meet all these demands, it is necessary to operate the engine in its optimal range. At high engine loads the optimal operation range becomes narrower as the engine comes closer to the knocking or to the misfire limit. The ambient conditions are of increasing importance in this range of operation. Variations in humidity influence the engine’s burn rate characteristics. An increase in humidity reduces the burn rate and increases the combustion duration. This increase in combustion duration has the same effect as retarding the time of ignition. Thus the thermal efficiency is reduced. Additionally, the engine is more likely to misfire as humidity increases. The cylinder temperature affects the engine fuel efficiency, knocking, exhaust gas temperature and particularly NOx emission. An increase in manifold air temperature results in higher NOx emission, heat transfer and knocking tendency. To avoid knocking, the time of ignition must be retarded resulting in lower engine efficiency. In this paper the effects of changes in humidity and temperature of the intake air on engine performance were examined in a lean burn pre-chamber natural gas engine. Tests on a single cylinder research engine were carried out. Effects on knocking and misfire limit, NOx emissions and fuel consumption were investigated depending on engine load. The interpretation of the results was supported by an extended analysis of losses.

Commentary by Dr. Valentin Fuster
2006;():431-436. doi:10.1115/ICEF2006-1568.

In this paper, a research on dynamic behavior of a diesel engine block is carried out in Finite Element Method (FEM). Natural frequencies and Modal shapes are obtained by FEM calculation. In order to validate the calculation result, a mode experiment is conducted by a single pulse excitation method. In the experiment, the natural frequencies, modal shapes and modal damping of the engine block are determined. Besides, based on the acquired vibration mode, the weak positions on this block are identified. Additionally, in order to acquire the experimental results accurately, some important factors included in this experiment such as the choice of excitation methods, structure supports, sensor installation and so on, should be given careful considerations. Comparison between the calculated results and the test data shows that the FEM model is reliable.

Commentary by Dr. Valentin Fuster

Lubrication and Friction

2006;():437-448. doi:10.1115/ICEF2006-1532.

Two gamma titanium aluminides (Daido RNT650 and HOWMET 45XD) with fully lamellar structure but with different colony sizes were studied using a single-grit pendulum (rotational) scratch tester in order to assess their abrasive wear resistances. The maximum depth of groove was ∼ 0.07 mm and the scratch velocity used was ∼ 1 m/s. Normal and tangential forces were monitored during each scratch. The material removal mechanisms were examined using a scanning electron microscope (SEM) and also measured using a laser profilometer. Extensive thermal softening was observed. Sizable fractures were revealed in the transverse direction; however, the role of these fractures in the chip formation depends on the microstructure of materials and the size of groove. The tribological properties were characterized by instantaneous specific energy and scratch hardness as related to the depth of the groove. The overall response of materials can be effectively characterized by the HEM (Hwang-Evans-Malkin) model and the PSR (proportional specimen resistance) model, even though the underlining material removal might be subjected to the different mechanisms. The TiAl with the larger colony or grain size exhibits a strong resistance to material loss or material removal (higher depth-independent specific energy) while exhibiting lower scratch hardness. The obtained depth-independent specific energy and scratch hardness can be used to screen the candidate materials depending on whether the application is sliding or impact dominant.

Topics: Pendulums , Titanium
Commentary by Dr. Valentin Fuster
2006;():449-455. doi:10.1115/ICEF2006-1566.

Lower emissions, reduced friction and low lubricant oil consumption are the main drivers for new gasoline engines. In terms of piston ring pack, the trend is to reduce ring tangential load and width. On the other hand, the main concern is to have proper ring conformability and lube oil control. This work presents the comparison of a baseline ring pack with a low friction pack in terms of friction, blow-by control and lube oil consumption. Besides ring width and tangential load reductions, evaluations of ring materials are also carried out. Narrow compression rings, 1.0 and 0.8 mm, were engine tested. PVD top ring was also tested and showed about 10% friction reduction compared to the usual Gas Nitrided one. 3-piece 1.5 mm oil rings were compared with the usual 2.0 mm ones. Being more flexible, the narrower oil rings can have same conformability with reduced tangential load. Friction was measured in the mono-cylinder SI Floating Liner engine at 5 operational conditions. Effect of cylinder roughness on friction is discussed by reciprocating bench tests. Compared with a typical 1.2/1.2/2.0 mm SI ring pack, the proposed 1.0/1.0/1.5 mm pack brought about 28% reduction in ring friction in the tested conditions, which would mean in about 1% of fuel savings in urban use.

Commentary by Dr. Valentin Fuster
2006;():457-473. doi:10.1115/ICEF2006-1587.

Modeling the thermal and mechanical behavior of a piston is crucial, as it allows for the evaluation of piston performance including piston dynamics and friction. These characteristics directly affect the efficiency, reliability, and lifespan of an internal combustion engine. This work migrates from the conventional parameterized piston modeling approach and uses a full CAD finite element modeling simulation for the evaluation of the piston’s thermal and mechanical behavior as well as the resultant hydrodynamic and contact forces and moments experienced by it. The analysis is performed for two different piston to cylinder bore nominal clearances, and for one of them at two different engine speeds, while assuming the piston is moving at the center of the cylinder bore with no transverse or tilting motion.

Commentary by Dr. Valentin Fuster
2006;():475-481. doi:10.1115/ICEF2006-1547.

The focus in research year 05 was on the optimization of optical coupling and minimization of laser energy especially in connection with very lean combustion and with high exhaust gas recirculation rates for low NOx emissions. The direct comparison of laser ignition with conventional spark ignitions, without any measures implemented in favor of laser ignition (high compression ratio, high turbulence ratio), consistently shows advantages in the case of laser ignition. With extension of the Lambda window, in the case of a spark ignition engine with a 2.4 1 piston displacement it is possible to shift the engine 0.3 units in the direction of “lean combustion” (possible reduction of NOx level less than 30% of the state of the art); EGR compatibility is increased by about 15% to a recirculation rate of about 40%. With regard to EGR compatibility, in coordination with SWRI (HEDGE Program) similar tests on determination of potential were carried out as well. In this case too no essential measures were implemented in favor of the exploitation of the potential of laser ignition; however, a minor increase of the compression ratio already allows recognition of the theoretically possible and expected potentials. Regarding stoichiometric conditions, from the viewpoint of the researchers working jointly on the project it is possible to reduce the energy to less than 1 mJ. Conversely, in the event of the utilization of lean-burn combustion, appreciably more energy must be provided. Additionally, measures regarding combustion control in the area of the extended lean-burn limit must also be carried out. Only then is it possible to ensure optimal values for burning durations and the variation coefficient. Initial results in this regard will also be presented.

Topics: Lasers , Engines
Commentary by Dr. Valentin Fuster

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