bluuebunny/crossref_metadata_2025 huggingface dataset:
On-Site Emissions and Fuel Consumption Measurement to Compare Locomotive Fuel Injector Performance
Authors: Wayne W. Scott , Barnett Ryan A. , Cutright Jeffrey M. , Stewart Ted E.
Published: September 2008

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.
Effects of Liner Surface Texturing on Ring/Liner Friction in Large-Bore IC Engines
Authors: Takata Rosalind , Li Yong , Wong Victor W.
Published: September 2008

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.
Specific Energy and Scratch Hardness of Gamma Titanium Aluminides Subjected to Single-Grit Pendulum Scratching
Authors: Wang Hong , Lin Hua-Tay , Wereszczak Andrew A. , Yang Nan , Jensen Jeff A.
Published: September 2008

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.
The Effect of Sulfur on Methane Partial Oxidation and Reforming Processes for Lean NOx Trap Catalysis
Authors: Parks James E. , Ponnusamy Senthil
Published: September 2008

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.
Measurement of the Percentage of Biodiesel in Blends With a Commercial Dielectric Fuel Sensor
Authors: Jenkins Carey , Mastbergen Daniel , Stanglmaier Rudolf
Published: September 2008

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.
System Model for Selective NOx Recirculation (SNR) to be Used in Stationary Lean-Burn Natural Gas Engines
Authors: Zimmerman A. , Tissera C. , Tatli E. , Clark N. , Atkinson R. , Thompson G. , Turton R.
Published: September 2008

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.
Performance of Homogenous Charge Compression Ignition (HCCI) Engine With Premixed Methane/Air Supported by DME for Electrical Power Generation Application
Authors: Keshavarz Mojtaba , Jazayeri Seyed Ali
Published: September 2008

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.
Direct Injection and Charge Stratification in a 50 cc Two-Stroke Engine: CFD Studies and Test Bench Results
Authors: Zanforlin S. , Musu E. , Frigo S. , Gentili R.
Published: September 2008

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.
The Numerical Study on the Performance Evaluations and Flow Structures for the Diffuser of Centrifugal Compressor in a Marine Engine Turbocharger
Authors: Kim Hong-Won , Ryu Seung-Hyup , Park Jong-Il , Ghal Sang-Hak , Ha Ji-Soo
Published: September 2008

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.
GE Jenbacher’s Update on Laser Ignited Engines
Authors: Herdin Gu¨nther , Klausner Johann , Weinrotter Martin , Graf Josef , Wimmer Andreas
Published: September 2008

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.
NOx Reduction of a Medium Speed Diesel Engine Using a Charge Air Moisturizer System
Authors: Park Hyoung-Keun , Ghal Sang-Hak , Kim Byong-Seok , Kim Ki-Doo , Kim Jong-Suk
Published: September 2008

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.
Impact of Hydrogen Assisted Lean Operation (HALO) on Natural Gas Engine Combustion
Authors: Smutzer Chad , Breault Ronald , Wilson Robert P.
Published: September 2008

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.
A Comparison of Imaging of Compression Ignition Phenomena of Iso-Octane, Indolene, and Gasoline Fuels in a Single-Cylinder Research Engine
Authors: Zigler Bradley T. , Walton Stephen M. , Assanis Dimitris , Perez Elizabeth , Wooldridge Margaret S. , Wooldridge Steven T.
Published: September 2008

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.
Integrated Modelling of Fuel Influence on Common Rail Injection System Performance
Authors: Chiavola O. , Palmieri F. , Chiatti G.
Published: September 2008

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.
Effects of Humidity and Ambient Temperature on Engine Performance of Lean Burn Natural Gas Engines
Authors: Wimmer Andreas , Schnessl Eduard
Published: September 2008

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.
An Experimental and Modeling Study of HCCI Combustion Using n-Heptane
Authors: Li Hailin , Guo Hongsheng , Neill W. Stuart , Chippior Wally , Taylor Joshua D.
Published: September 2008

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.
Low Friction Ring Pack for Gasoline Engines
Authors: Tomanik Eduardo , Ferrarese Andre
Published: September 2008

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.
Vibration Analysis of an Engine Cylinder Block
Authors: Gao Wenzhi , Hao Zhiyong
Published: September 2008

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.
Engine Analysis of Single Cylinder DI Diesel Engine Fuelled With Sunflower Oil, Sunflower Oil Methyl Ester and Its Blends
Authors: Anandram V. , Ramakrishnan S. , Karthick J. , Saravanan S. , LakshmiNarayanaRao G.
Published: September 2008

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.
Fiber Delivered Systems for Laser Ignition of Natural Gas Engines
Authors: Yalin Azer P. , Joshi Sachin , Reynolds Adam , Defoort Morgan , Willson Bryan , Galvanauskas Almantas , Matsuura Yuji , Miyagi Mitsunobo
Published: September 2008

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.
Landfill Gas Fueled HCCI Demonstration System
Authors: Blizman Brandon J. , Makel Darby B. , Mack J. Hunter , Dibble Robert W.
Published: September 2008

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.
Effects of Different Biodiesel Blends on Heat Release and Its Related Parameters
Authors: Parvate-Patil Girish , Vasquez Manuel , Payne Malcolm
Published: September 2008

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.
An Improved Phenomenological Soot Formation Sub-Model for 3-D Diesel Engine Simulations: Extension to Agglomeration of Particles Into Clusters
Authors: Boulanger Joan , Liu Fengshan , Neill W. Stuart , Samllwood Gregory J.
Published: September 2008

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.
Testing of Syntroleum Synthetic Diesels in Diesel Generators Suitable for Alaska
Authors: Telang Aseem , Witmer Dennis , Lin Chuen-Sen , Schmid Jack , Johnson Thomas , Kenny Tristan
Published: September 2008

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.
Analysis of parameter effects on sound energy decay in coupled volume systems
Authors: Bradley David Timothy
Published: September 2008

Several noise criteria methods commonly used in architectural acoustics have been quantitatively related to noise perception and task performance under a variety of ventilation systems-induced background noise conditions. Noise criteria, balanced noise criteria, room criteria, room criteria mark II, and A-weighted equivalent sound pressure level were examined. The first phase of the project included noise conditions controlled to be non-time-varying and nontonal, with neutral, rumbly, roaring, or hissy characteristics. An intermediate study examined exposure time length and types of performance tasks used. The final phase included noise conditions containing various levels of discrete tones from 120 to 595 Hz. Under each noise, subjects completed performance tasks and perception questionnaires. Results indicate task performance was significantly affected by perception of noise, but this relationship was not fully demonstrated by the criteria systems analyzed. The five criteria were generally well suited in describing subjective loudness perception, but some discrepancies in criteria spectral quality ratings and subjective perception existed. Finally, perception of annoyance changed based on the frequency and prominence of tones in noise, but these changes were not reflected in the criteria level or spectral quality ratings. Modifications to the existing criteria are recommended.
AN INTEGRAL FORMULA AND ITS APPLICATION TO NORMAL EULER NUMBER
Authors: GE JIANQUAN , TANG ZIZHOU
Published: September 2008

We establish a general integral formula over sphere, and then apply it to give a geometrical proof of the celebrated topological theorem of Lashof and Smale, which asserts that the tangential degree of the tangent sphere bundle coincides with the normal Euler number for an immersion Mn → E2n of an oriented closed manifold into Euclidean space of twice dimension.
ORBIFOLD COHOMOLOGY OF HYPERTORIC VARIETIES
Authors: GOLDIN REBECCA F. , HARADA MEGUMI
Published: September 2008

Hypertoric varieties are hyperkähler analogues of toric varieties, and are constructed as abelian hyperkähler quotients T*ℂn//// T of a quaternionic affine space. Just as symplectic toric orbifolds are determined by labelled polytopes, orbifold hypertoric varieties are intimately related to the combinatorics of hyperplane arrangements. By developing hyperkähler analogues of symplectic techniques developed by Goldin, Holm, and Knutson, we give an explicit combinatorial description of the Chen–Ruan orbifold cohomology of an orbifold hypertoric variety in terms of the combinatorial data of a rational cooriented weighted hyperplane arrangement [Formula: see text]. We detail several explicit examples, including some computations of orbifold Betti numbers (and Euler characteristics).
RUELLE TYPE L-FUNCTIONS VERSUS DETERMINANTS OF LAPLACIANS FOR TORSION FREE ABELIAN GROUPS
Authors: KUROKAWA NOBUSHIGE , WAKAYAMA MASATO , YAMASAKI YOSHINORI
Published: September 2008

We study Ruelle's type zeta and L-functions for a torsion free abelian group Γ of rank ν ≥ 2 defined via an Euler product. It is shown that the imaginary axis is a natural boundary of this zeta function when ν = 2, 4 and 8, and in particular, such a zeta function has no determinant expression. Thus, conversely, expressions like Euler's product for the determinant of the Laplacians of the torus ℝν/Γ defined via zeta regularizations are investigated. Also, the limit behavior of an arithmetic function arising from the Ruelle type zeta function is observed.
BIQUOTIENT ACTIONS ON UNIPOTENT LIE GROUPS
Authors: PÜTTMANN ANNETT
Published: September 2008

We consider pairs (V, H) of subgroups of a connected unipotent complex Lie group G for which the induced V × H-action on G by multiplication from the left and from the right is free. We prove that this action is proper if the Lie algebra 𝔤 of G is 3-step nilpotent. If 𝔤 is 2-step nilpotent, then there is a global slice of the action that is isomorphic to ℂn. Furthermore, a global slice isomorphic to ℂn exists if dim V = 1 = dim H or dim V = 1 and 𝔤 is 3-step nilpotent. We give an explicit example of a 3-step nilpotent Lie group and a pair of 2-dimensional subgroups such that the induced action is proper but the corresponding geometric quotient is not affine.
WEIGHTED COMPOSITION OPERATORS FROM F(p, q, s) TO BLOCH TYPE SPACES ON THE UNIT BALL
Authors: ZHOU ZE-HUA , CHEN REN-YU
Published: September 2008

Let ϕ(z) = (ϕ1(z),…,ϕn(z)) be a holomorphic self-map of B and ψ(z) a holomorphic function on B, where B is the unit ball of ℂn. Let 0 < p, s < +∞, -n - 1 < q < +∞, q+s > -1 and α ≥ 0, this paper characterizes boundedness and compactness of weighted composition operator Wψ,ϕ induced by ϕ and ψ between the space F(p, q, s) and α-Bloch space [Formula: see text].
AN ALGORITHMIC APPROACH TO PREFERENCE REPRESENTATION
Authors: YÁÑEZ J. , MONTERO J. , GÓMEZ D.
Published: September 2008

In a previous paper, the authors proposed an alternative approach to classical dimension theory, based upon a general representation of strict preferences not being restricted to partial order sets. Without any relevant restriction, the proposed approach was conceived as a potential powerful tool for decision making problems where basic information has been modeled by means of valued binary preference relations. In fact, assuming that each decision maker is able to consistently manage intensity values for preferences is a strong assumption even when there are few alternatives being involved (if the number of alternatives is large, the same criticism applies to crisp preferences). Any representation tool, as the one proposed by the authors, will in principle play a key role in order to help decision makers to understand their preference structure. In this paper we introduce an alternative approach in order to avoid certain complexity issues of the initial proposal, allowing a close representation easier to be obtained in practice.
A NOTE ON THE ESTIMATION OF MISSING PAIRWISE PREFERENCE VALUES: A UNINORM CONSISTENCY BASED METHOD
Authors: CHICLANA FRANCISCO , HERRERA-VIEDMA ENRIQUE , ALONSO SERGIO , HERRERA FRANCISCO
Published: September 2008

Dealing with incomplete information is an important problem in decision making. In this paper, we present a short discussion on this topic and a new estimation method of missing values in an incomplete fuzzy preference relation which is based on the modelling of consistency of preferences via a representable uninorm.
SEQUENTIAL CONSENSUS FOR SELECTING QUALIFIED INDIVIDUALS OF A GROUP
Authors: BALLESTER MIGUEL A. , GARCÍA-LAPRESTA JOSÉ LUIS
Published: September 2008

In this paper we analyze a group decision procedure that follows a recursive pattern. In the first stage, the members of a group show their opinions on all the individuals of that group, regarding a specific attribute, by means of assessments within an ordered set, e.g. the unit interval or a finite scale. Taking into account this information, some aggregation operators and a family of thresholds, a subgroup of individuals is selected: those members whose collective assessment reach a specific threshold. Now only the opinions of this qualified subgroup are taken into account and a new subgroup emerges in the implementation of the aggregation phase. We analyze how to put in practice this recursive procedure in order to provide a final subgroup of qualified members. We have considered the minimum as aggregation operator. Thus, the collective assessment is just the worst of the individual assessments. This idea corresponds to qualify individuals whenever all the individual assessments reach the fixed threshold.
MULTI-ATTRIBUTE DECISION MAKING BASED ON LABEL SEMANTICS
Authors: LAWRY JONATHAN , HE HONGMEI
Published: September 2008

We propose label semantics as an integrated representation framework for probabilistic uncertainty and fuzziness in multiple-attribute decision making problems. Linguistic attribute hierarchies are then introduced as a means of modelling the complex and often imprecise functional relationships between low-level attributes or measurements and high-level decision or classification variables. Within this framework we introduce linguistic decision trees as a tool for information aggregation in multi-attribute decision problems and describe the process of information propagation through a hierarchy of linked decision trees. In addition, we consider the ranking of different alternatives or examples based on their linguistic descriptions of a high-level utility variable. Finally, we discuss how linguistic decision trees embedded in attribute hierarchies can be learnt from data.
HYPOTHESES MANAGEMENT FOR DISORDER DIAGNOSIS IN A HIERARCHICAL FRAMEWORK
Authors: DIAZ JAVIER , SANDRI SANDRA , RIFQI MARIA , BOUCHON-MEUNIER BERNADETTE
Published: September 2008

We propose the use of a knowledge based framework for diagnosis in which the knowledge base consists of particular instances of general hierarchical disorder models. We study how to select which manifestation (symptom, malfunction) to query in order to reduce a set of competing diagnosis hypotheses (disorders), none of them completely satisfying, considering only the observed manifestations. We propose to use general information about the order in which competing disorder models should be probed first to guide us on the task of selecting which particular disorder instances to try to confirm first. We propose to then order which manifestation instances to probe, the presence or absence of which will help us to either confirm or eliminate that hypothesis, according to the principle that "(manifestation) instances that share some characteristics with the instance of manifestation that generated the whole process, but which completely disagree in relation to other characteristics" should be probed first.