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Technical Paper

Application of Shape Memory Heat Engines to Improving Vehicle Fuel Economy

1996-04-01
91A128
Shape memory materials undergo temperature-induced martensitic phase transformations that involve reversible dimensional changes. In performing these changes in shape, the shape-memory material is able to do work against external constraints, and this is the basis for shape-memory low-temperature heat engines. The transformation temperatures on heating and cooling are often not very different (little hysteresis) and are well defined and reproducible. Furthermore, these temperatures can be adjusted by varying the composition of the shape memory alloy. Internal combustion engines dissipate approximately two-thirds of the fuel energy as heat to the exhaust and coolant systems. A low-temperature heat engine could convert a fraction of this heat energy to useful work. This paper discusses the conceptual basis for the application of shape memory heat engines to internal combustion engine powered vehicles. Metallurgical and thermodynamic factors are discussed, as well as engine efficiency.
Technical Paper

The Development of Plastic Lenses for Vehicle Headlamps

1996-04-01
91A111
The pending changes in European law enabling the use of plastic lenses on vehicle headlamps provide an opportunity for further advancement of vehicle styling, lighting performance and aerodynamic efficiency. Plastic lenses can also provide a useful weight saving and contribute to energy savings during the lifetime of the vehicle. This paper discusses the current requirements, technologies and solutions for plastic lenses, and indicates the way this advance can impact on the evolution of lighting products.
Technical Paper

Fe Model Adjustment of a Composite Material Car-Body By Means of Experimental Modal Analysis on the Prototype

1996-04-01
91A095
A procedure adopted to verify and update the finite elements model of an electric powered car-body manufactured from composite materials is described. Experimental results, obtained from modal testing of the prototype, are used in order to identify and correct discrepancies in the FE model. The availability of a highly reliable FE model allows to simulate structural modifications by computer, optimizing the use of composites and reducing in the same time at minimum prototypes construction. The approach followed suggests a possible remarkable reduction in product development costs and duration. The work has been performed within a larger program for the development of thermoplastic composite materials, with particular attention to transportation market.
Technical Paper

Optimisation of Diesel Engines Converted to High Compression Spark Ignition (SI) Natural Gas Operation

1988-03-01
871149
There is a strong interest around the world in natural gas as an alternative fuel. This paper is concerned with the option of converting diesel engines to spark ignition operation. Although this may appear to be an outrageous thermodynamic action, it is preferable to using natural gas in a low compression gasoline engine conversion. An investigation is described in which engine maps were produced for a 5.6 litre direct injection diesel engine converted to CNG. The diesel operating characteristics have been compared with those of the spark ignition conversion at compression ratios of 18:1 (the original diesel value), 15:1 and 13:1. Detailed data are presented for the 15:1 compression ratio. These test results are supplemented by results for other diesel conversions. The use of these engines in bus fleet operations is also discussed.
Technical Paper

Trends and Forecasts for Turbocharging

1988-03-01
871147
Predictable and unpredictable forces will change the direction of the charge-air systems industry. The driver of diesel engine development will be the stringent emissions regulations of the 1990s. The drivers in the gasoline engine market will be improved fuel economy, performance, durability and emissions. Forces will also influence the charge-air marketplace, including changes in emission standards, national fiscal policies, political issues, fuel prices, alternate fuels and consumer tastes. The world community mandate for engines that are clean, quiet, durable and fuel efficient will be satisfied, increasingly, by first-tier component suppliers developing integrated systems solutions.
Technical Paper

Performance and Exhaust Emission in Spark Ignition Engine Fueled with Methanol-Butane Mixture

1988-03-01
871165
To improve the cold startability of methanol, methanol-butane mixed fuel was experimented. Engine performance and exhaust emissions are obtained with methanol-butane mixed fuel. These characteristics are compared with those of methanol and gasoline. The mixing ratios of methanol and butane are 50:50 (M50), 80:20 (M80), and 90:10 (M90) based on the calorific value. As a result, M90 produces more power than gasoline and more or less than methanol depending on the engine speed and the excess air ratio. Brake horse power of M90 is higher than that of gasoline by 5 - 10 %, and brake specific fuel consumption is smaller than that of gasoline by 17 % to the maximum based on the calorific value. NOx emission concentrations for M90 are lower than those for gasoline and higher than those for methanol because of the effect of butane, CO emission concentrations are somewhat lower than those for methanol and gasoline.
Technical Paper

Engine Control System for Lean Combustion

1988-03-01
871171
In order to achieve lean burn engine control system, it is necessary to develop high accuracy air fuel ratio control technology including transient driving condition and lean burn limit expansion technology. This paper describes the following. 1 The characteristics of the transient response of the fuel supply are clarified when various kinds of air flow measuring methods and fuel injection methods are used. 2 To achieve stable combustion in lean mixture, fine fuel droplet mixture, whose diameter is less than 40 μm, needs to be supplied.
Technical Paper

“Passenger Vehicle Petrol Consumption - Measurement in the Real World”

1988-03-01
871159
A survey of the in-service fuel consumption of passenger vehicles and derivatives in the Australian fleet was carried out in 1984-85. Seven hundred and four owners across Australia took part in the survey. Vehicle owners reported by questionnaire the amount of fuel used during four tank fills of normal operation, the distance travelled, and other details of the operating circumstances. The survey shows a clear downward trend in the fuel consumption of the Australian passenger fleet. The data also provides comparisons of actual fuel consumption obtained on the road, with laboratory derived values for fuel consumption. Vehicles in a sub-set of 40 were fitted with fuel flow meters during the survey and tested to Australian Standard 2077 for fuel consumption. The questionnaire method is shown to be a valid and accurate technique for determining in-service fuel consumption.
Technical Paper

A Procedure for Evaluating Cycle Emissions from Raw Exhaust Gas Analyses

1988-03-01
871194
A procedure has been developed for evaluating equivalent drive cycle emission results from raw exhaust gas emissions data obtained from an engine under test on a computer controlled Vehicle Simulator Engine Dynamometer. The emitted species data is integrated with the air intake flow rate to determine the total mass of emissions, after correcting for the reduction in exhaust gas mass due to precipitation of the moisture of combustion. This procedure eliminates the need for the Constant Volume Sample (CVS) System attached to the vehicle exhaust while undergoing simulated drive testing on a chassis dynamometer to evaluate compliance of the test vehicle with the Australian Design Rules, ADR27 and ADR37. Sources of error with the procedure are examined by comparing the fuel consumption measured using a volumetric technique during the test with that evaluated by a carbon balance procedure as given in the Australian Design Rules.
Technical Paper

A Numerical Simulation of the Unsteady Laminar Flame Propagation in a Closed Cylindrical Combustion Bomb

1988-03-01
871174
Unsteady laminar flame propagation confined in a closed cylindrical combustion bomb is studied by numerical computation for an axisymmetric two-dimensional laminar flame. Computation includes complete two-dimensional unsteady Navier-Stokes equations of change for a chemically reacting propane-air mixture. Implicit Continuous fluid Eulerian, Arbitrary Lagrangian Eulerian finite difference technique, simplified reaction kinetics models, and artificial flame stretching transformation and inverse transformation were adopted in the calculation. Physically realistic flame behavior can be demonstrated even with rather coarse computing cell size, simplified reaction kinetics models, and personal computer level low power computing machines.
Technical Paper

Use of Statistical Energy Analysis Method to Predict Sound Transmission Loss of Sound Barrier Assemblies

1999-05-17
1999-01-1707
Statistical Energy Analysis (SEA) method is used to predict Sound Transmission Loss (STL) of sound barrier assemblies (SBA) commonly used in automotive dashmat design. Tests are performed for dashmat plaques with and without design features, and SEA equations have been used for predicting transmission loss with acceptable accuracy below the interception (cavity resonance) frequency. For frequency range higher than interception point, the SEA software used overestimates STL. For dashmat tests with design features, test results and SEA predictions are generally agreeable.
Technical Paper

Some New Diagnostic Parameters for Reciprocating Engines

1999-05-17
1999-01-1714
Condition monitoring through signal analysis is not as well established for reciprocating engines as it is for rotating machines. One of the reason is that it has to deal with non-stationary vibrations. In this paper, some new statistical indicators are defined for the detection and separation of close transient events. They can also be used for diagnostic purposes, for instance for valve mechanics or for combustion rises. Their performances are compared on real vibrations of a small 4 cylinder diesel engine and it is finally verified that they allow the reconstruction of the engine cycle.
Technical Paper

Effect of High Squish Combustion Chamber on Simultaneous Reduction of NOx and Particulate from a Direct-Injection Diesel Engine

1999-05-03
1999-01-1502
In this study it is tried to reduce NOx and particulate emissions simultaneously in a direct injection diesel engine based on the concept of two-stage combustion. At initial combustion stage, NOx emission is reduced with fuel rich combustion. At diffusion combustion stage, particulate emission is reduced with high turbulence combustion. The high squish combustion chamber with reduced throat diameter is used to realize two-stage combustion. This combustion chamber is designed to produce strong squish that causes high turbulence. When throat diameter of the high squish combustion chamber is reduced to some extent, simultaneous reduction of NOx and particulate emissions is achieved with less deterioration of fuel consumption at retarded injection timing. Further reduction of NOx emission is realized by reducing the cavity volume of the high squish combustion chamber. Analysis by endoscopic high speed photography and CFD calculation describes the experimental results.
Technical Paper

A Photographic Investigation of Multi-Stage Fuel Injection in a Single Cylinder DI Diesel Engine

1999-05-03
1999-01-1501
Increasing concern about the impact of internal combustion engines on the environment has led to ever more stringent emission legislation, and the introduction of more sophisticated equipment to enable the requirements to be achieved. One way of improving the emissions from direct injection (DI) diesel engines is to use multi-stage fuel injection, and an investigation performed on such a system is reported in this paper. In this case, the multi-stage fuel injector caused an increase in the exhaust smoke at low load, and an in-cylinder photographic technique was used to examine why this occurred. A multi-stage fuel injector with a VCO nozzle was fitted to a small, high-speed, direct injection diesel engine fitted with a transparent piston for optical access. The combustion process was filmed using a high-speed 16 mm cine camera, and the fuel injection process was illuminated by a high power, copper-vapour laser.
Technical Paper

The Autoignition Behavior of Surrogate Diesel Fuel Mixtures and the Chemical Effects of 2-Ethylhexyl Nitrate (2-EHN) Cetane Improver

1999-05-03
1999-01-1504
The oxidation of surrogate diesel fuels composed of mixtures of three pure hydrocarbons with and without their cetane numbers chemically enhanced using 2-ethylhexyl nitrate (2-EHN) is studied in a variable pressure flow reactor over a temperature range 500 - 900 K, at 12.5 atmospheres and a fixed reaction time of 1.8 sec. Changes in both low temperature, intermediate temperature, and hot ignition chemical kinetic behavior are noted with changes in the fuel cetane number. Differences appear in the product distribution and in heat release generated in the low and intermediate temperature regimes as cetane number is increased. A chemically enhanced cetane fuel shows nearly identical oxidation characteristics to those obtained using pure fuel blends to produce the enhanced cetane value. The decomposition chemistry of 2-EHN was also studied. Pyrolysis data of 10% 2-EHN in n-heptane and toluene are reported.
Technical Paper

A Six-Stroke DI Diesel Engine Under Dual Fuel Operation

1999-05-03
1999-01-1500
A six-stroke DI diesel engine proposed by the authors had second compression and combustion processes which were added on a conventional four-stroke diesel engine. This engine had the first and second power strokes before the exhaust stroke. Numerical predictions and experiments previously carried out had shown that this six-stroke diesel engine could reduce NO exhaust emission. Further, the ignition delay of the second combustion process could be shortened by a high temperature effect in the second compression stroke. This advantage of short ignition delay could be utilized for an ignition improvement of a fuel with low cetane number. In the engine system reported here, a conventional diesel fuel was supplied as the fuel of first combustion process, and in the second combustion process, methanol was supplied.
Technical Paper

A Comparison of Gasoline Direct Injection and Port Fuel Injection Vehicles: Part II - Lubricant Oil Performance and Engine Wear

1999-05-03
1999-01-1499
Four 1998 Mitsubishi Carismas, two equipped with direct injection (GDI) and two with port fuel injection engines (PFI) were tested in a designed experiment to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant type on engine wear and engine oil performance parameters. Fuel types were represented by an unadditised base fuel meeting EEC year 2000 specifications and the same base fuel plus synthetic deposit control additive packages. Crankcase oils were represented by two types (1) a 5W-30 API SJ/ILSAC GF-2 type engine oil and (2) a 10W-40 API SH/CF ACEA A3/ B3-96 engine oil. The program showed that specific selection of oil additive chemistry may reduce formation of intake valve deposits in GDI cars.. In general, G-DI engines produced more soot and more pentane insolubles and were found to be more prone to what appears to be soot induced wear than PFI engines.
Technical Paper

Characterisation of the Injection-Combustion Process in a D.I. Diesel Engine Running with Rape Oil Methyl Ester

1999-05-03
1999-01-1497
The objective of the work presented here is to evaluate the potential of rape oil methyl ester (RME) to improve the combustion process in a high-speed direct injection (HSDI) Diesel engine equipped with high-pressure common-rail injection system. The study, based on the comparison of three different fuels (standard gas-oil, RME and 30% RME/gas-oil mixture), takes into account the main aspects that control Diesel combustion, from the injection rate characteristics to the spray behaviour characterised using an optical pressurised chamber. This global study of the whole injection-combustion process allows identifying some causes of the decrease in pollutant emissions observed when the engine operates with RME.
Technical Paper

What Fuel Economy Improvement Technologies Could Aid the Competitiveness of Light-Duty Natural Gas Vehicles?

1999-05-03
1999-01-1511
The question of whether increasing the fuel economy of light-duty natural gas fueled vehicles can improve their economic competitiveness in the U.S. market, and help the US Department of Energy meet stated goals for such vehicles is explored. Key trade-offs concerning costs, exhaust emissions and other issues are presented for a number of possible advanced engine designs. Projections of fuel economy improvements for a wide range of lean-burn engine technologies have been developed. It appears that compression ignition technologies can give the best potential fuel economy, but are less competitive for light-duty vehicles due to high engine cost. Lean-burn spark ignition technologies are more applicable to light-duty vehicles due to lower overall cost. Meeting Ultra-Low Emission Vehicle standards with efficient lean-burn natural gas engines is a key challenge.
Technical Paper

Performance and Emissions of an LPG Lean-Burn Engine for Heavy Duty Vehicles

1999-05-03
1999-01-1513
Performance and emissions of an LPG lean burn engine for heavy duty vehicles were measured. The piston cavity, swirl ratio, propane - butane fuel ratio, and EGR were varied to investigate their effects on combustion, and thus engine performance. Three piston cavities were tested: a circular flat-bottomed cavity with sloped walls (called the “bathtub” cavity), a round bottomed cavity (called the “dog dish” cavity), and a special high-turbulence cavity (called the “nebula” cavity). Compared to the bathtub and dog dish cavities, the nebula type cavity showed the best performance in terms of cyclic variation and combustion duration. It was capable of maintaining leaner combustion, thus resulting in the lowest NOx emissions. High swirl improved combustion by achieving a high thermal efficiency and low NOx emissions. In general, as the propane composition increased, cyclic variation fell, NOx emissions increased, and thermal efficiency was improved.
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