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Long range, extended endurance, variable speed autonomous underwater vehicles (AUVs) appear to be an attractive solution to problems of environmental monitoring, geophysical exploration and military surveillance. To undertake their intended autonomous missions these vehicles require reliable and cost-effective power systems. Although there is presently an extensive interest in untethered AUVs, with far reaching efforts being made in a variety of activities, only limited headway has been made in the development of power systems which could be readily integrated into these vessels. The majority of current research is focusing on increasing the underwater endurance and hence cost effectiveness of the vehicle by developing compact, lightweight high energy density power systems for vessel propulsion. Subsequently, a number of different power systems have been investigated proposed, designed and developed.

Mitsubishi Motors Corporation (MMC) has developed a new V configured 8 cylinder turbocharged and intercooled diesel engine (8M22T1) for the heavy-duty truck market. The engine is one of the first in its class to feature a common rail fuel injection system. This advanced engine management system was selected to meet the challenges of ever tightening emission regulation, specifically in the areas of smoke and noise. The 8M22T1 embodies a number of design innovations which have resulted in significant improvements in performance, fuel economy, durability and reliability.

Water vapour is a main constituent of exhaust gas recirculation (EGR) in diesel engines and its influence on combustion and emissions were investigated. The following effects of the water vapour were examined experimentally: the effect of replacing part of the inlet charge oxygen (dilution effect), the effect of the higher specific heat capacity of water vapour in comparison with that of oxygen it replaces (thermal effect), the effect of dissociation of water vapour (chemical effect), as well as the overall effect of water vapour on combustion and emissions. Water vapour was introduced into the inlet charge, progressively, so that up to 3 percent of the inlet charge mass was displaced. This was equivalent to the amount of water vapour contained in 52 percent by mass of EGR for the engine operating condition tested in this work.

The octane requirement increase (ORI) observed in spark ignition engines essentially occurs due to the effect of deposits in the combustion chamber changing the heat transfer characteristics between the end-gas and the combustion chamber walls. In addition, the volume occupied by deposits produces a change in compression ratio inside each cylinder which also contributes to ORI. However, all the ORI observed in spark ignition engines cannot be explained by these physical effects alone and for some time the existence of a chemical mechanism of ORI has been postulated. Evidence is presented from a laboratory experiment which demonstrates that deposits are indeed able to influence the ignition delay times of fuel-air mixtures by providing a source of active species which help initiate autoignition. Such effects have also been observed in some engine experiments, thus confirming the existence of chemically based ORI.

Smoke is emitted in diesel engines because fuel injected into the combustion chamber burns with insufficient oxygen. The emission smoke from diesel engines is a very important air pollution problem. Smoke emission, which is believed to be largely related to the diffusion combustion in diesel engines, results from pyrolysis of fuel not mixed with air. Therefore, the smoke emission is dependent on diffusion combustion phenomena, which are controlled by engine parameters. This paper presents an analysis of combustion by relating the smoke emission with heat release in diesel engines. An analysis is made of the diffusion combustion quantity, the smoke emission, and the fraction of diffusion combustion as related to the engine parameters which are air-fuel ratio, injection timing, and engine speed.

Inert injection is an often-used technique to reduce NOx emissions from engines. Here the effects of a new Mitsubishi water injection system for a direct injection (DI) Diesel engine on exhaust emissions are examined. Stoichiometric flame temperature correlations of thermal NOx emissions for conventional gas turbine combustors provide an activation energy to form NO of approximately 135 kcal/g-mol, the value for the Zeldovich mechanism with O/O2 equilibrium. Two theoretical limiting temperatures determined to bracket NOx emissions data for gas turbines are computed for the Diesel engine considered here. At low water to fuel ratios, the reductions of NOx for the DI Diesel engine are less than predicted for uniform distribution of an inert throughout the charge, but as the water to fuel ratio is increased the reductions are bounded successfully by the limiting temperatures.

Experimental studies of fuel utilisation during the early stages of engine warm-up after cold-starts are reported. The investigation has been carried out on a 1.81, 4 cylinder spark-ignition engine with port electronic fuel injection. The relationship between fuel supplied and fuel accounted for by the analysis of exhaust gas composition shows that a significant mass of fuel supplied is temporarily stored or permanently lost. An interpretation of data is made which allows time-dependent variations of these to be separately resolved and estimates of fuel quantities made. The data covers a range of cold-start conditions down to -5°C at which, on a per cylinder basis, fuel stored peaks typically at around 0.75g and a total of 1g is returned over 100 seconds of engine running. Fuel lost past the piston typically accounts for 2g over 200 to 300 seconds of running.

On the whole, the assessment criteria leading to the selection of liquefied natural gas (LNG) as an alternate fuel have been fairly well developed. However, the technology needs have not been adequately addressed in many instances resulting in demonstration projects less successful than anticipated. Because LNG technology is more complex than that of conventional fuels such as gasoline and diesel, and because LNG as a transportation fuel is in the early stages of implementation, the technology needs must be very carefully addressed. This paper presents an overview of the design issues considered important to LNG fueling in ground transportation.

Ford Motor Company has introduced its dedicated Natural Gas Vehicle (NGV) trucks as mid-year 1997 offerings to complement its dedicated Crown Victoria and bi-fuel Qualified Vehicle Modifier (QVM) product line-up. The 5.4L F-250 full-size pick-up truck and the 5.4L E-250/E-350 full-size vans are production vehicles maintaining Original Equipment Manufacturer (OEM) quality and warranty while complying with all applicable corporate, federal and state requirements. Both trucks are the first OEM vehicles to certify at the Super Ultra Low Emission Vehicle (SULEV) California medium-duty vehicle standard, the Federal Ultra Low Emission Vehicle (ULEV) standard, and the Federal Inherently Low Emission Vehicle (ILEV) emission standard. The use of natural gas (NG) as a vehicle fuel required unique hardware changes in the areas of fuel storage, fuel metering, and the emission control system.

A group of GM C-2500 heavy-duty and GM C-1500 light-duty trucks were modified to bi-fuel compressed natural gas (CNG)/gasoline and liquefied petroleum gas (LPG)/gasoline vehicles. The fuel management systems used for different model year vehicles were introduced. The Alternative Fuel Technology (AFT) System used for 1997 GM C-2500 trucks is discussed in detail. AFT is an automatic switching bi-fuel system which is able to control fuel flow rate, spark timing, and EGR, and perform On-Board Diagnostics (OBD-II). The exhaust emissions of carbon monoxide (CO), total hydrocarbon (HC) and oxides of nitrogen (NOx) were measured using dilute sampling techniques. The vehicles tested were operated on a chassis dynamometer and run on the Federal Test Procedure (FTP) Urban Schedule.

This paper deals with the effects on diesel engine combustion and emissions of carbon dioxide and water vapour the two main constituents of EGR. It concludes the work covered in Parts 1, 2, and 3 of this series of papers. A comparison is presented of the different effects that each of these constituents has on combustion and emissions. The comparison showed that the dilution effect was the most significant one. Furthermore, the dilution effect for carbon dioxide is higher than that for water vapour because EGR has roughly twice as much carbon dioxide than water vapour. On the other hand, the water vapour had a higher thermal effect in comparison to that of carbon dioxide due to the higher specific heat capacity of water vapour. The chemical effect of carbon dioxide was, generally, higher than that of water vapour.

Alternative fuels are being evaluated in automotive applications in both commercial and government fleets in an effort to reduce emissions and United States dependence on diesel fuel. Vehicles and equipment have been operated using 100 percent biodiesel and various blends of biodiesel and diesel fuel in a variety of applications, including farming equipment and transit buses. This government study investigates the compatibility of four base fuels and six blends with elastomer and metallic components commonly found in fuel systems. The physical properties of the elastomers were measured according to American Society of Testing and Materials (ASTM) D 471, “Standard Test Method for Rubber Property-Effect of Liquids,” and ASTM D 412, “Standard Test Methods for Rubber Properties in Tension.” These evaluations were performed at 51.7°C for 0, 22, 70, and 694 hours. Tensile strength, hardness, swell, and elongation were determined for all specimens.

Raytheon E-Systems has developed and implemented an Individual Aircraft Tracking Program (IATP) that forms one element of a comprehensive Aircraft Structural Integrity Program (ASIP). This program aims to ensure the long-term structural integrity and continued airworthiness of a broad portion of the Federal Aviation Administration (FAA) Flight Inspection Fleet of aircraft. Specifically, six Learjet Model 60 and three Canadair Challenger CL601-3R aircraft are modified by Raytheon E-Systems to perform the Flight Inspection role for the FAA. Flight Inspection mission profiles are characterized by extensive operation below 2000 feet MSL (mean sea level). This low level, structurally harsh environment contrasts dramatically with typical corporate jet operational environments.

We have studied the fuel behavior in Port-injection gasoline engines as the following: 1. We have developed a 100%-sampling quantitative analysis method where fuel is sealed up in the intake port and cylinder at a specific point during firing operation, using an engine with intake and exhaust valves that are opened and closed by electronic control. 2. As a result of our analysis of steady and transient state characteristics of fuel behavior using this method, it was verified that the amount of wall-wetting fuel in the port and cylinder is apparently different before and after the warm-up process. As for transient fuel behavior, a delay in fuel transfer has been acknowledged in the amount of wall-wetting fuel not only in the port but also in the cylinder. Different from the existing indirect analysis, this method enables direct measurement of fuel behavior even during the actual firing operation.

A study was conducted to reduce unburned oil fractions in diesel particulate matter (PM) by improving oil consumption. A method utilizing radioisotope 14C was developed to measure the unburned oil fractions separately for the four paths by which oil is consumed: valve stem seals, piston rings, PCV system, turbocharger. The conversion ratio of oil consumption to PM was calculated by comparing the unburned oil emission rates with oil consumption rates, which were obtained by the use of the 35S tracer method. The result in an experimental diesel engine shows the highest conversion ratio for the oil leaking through the valve stem seals. The modifications to the engine were thereby focused on reducing the leakage of the stem seals. This stem seal modification, along with piston ring improvements, reduced oil consumption, resulting in the unburned oil fractions in PM being effectively reduced.

Engine calibrations are inexpensive methods for reducing exhaust emissions since only software modifications are required. The California Air Resources Board staff conducted a test program to investigate the effectiveness of engine calibration techniques to reduce the newly regulated aggressive driving exhaust emissions or “off-cycle” emissions. Consisting of stoichiometric and rich “bias” calibration, these engine calibration techniques were applied to fourteen late-model vehicles. The engine calibration techniques reduced the off-cycle emissions substantially on most vehicles. To comply with the proposed off-cycle standards for California low-emission vehicles and ultra-low-emission vehicles, these techniques will be a cost-effective method to reduce off-cycle emissions.

This paper discusses “Technical Excellence,” a set of qualities required by a Gas Turbine Engineering organization to be “Best In Class,” the key to a very successful business. The Aerospace Industry environment (market needs, economic pressures, and mode of operation) has been subjected to quantum changes during the last decade. This paper discusses how these changes in our environment are affecting the qualities required to achieve “Technical Excellence.” The author shows that, in spite of the increased challenges, “Technical Excellence” can be met by taking advantage of the very tools and methods derived from our Industry internal upheavals, provided we aggressively address the pitfalls inherent in such revolutionary changes.

The environmental impact of automobiles and components is of growing importance both in the public discussion and in the complex decision finding process for future car concepts. Especially more and more conflicts of objectives occur between technical, economical, ecological and political requirements. For a lasting improvement of environmental compatibility and recyclability as an element of the so-called „sustainable development” of automobiles and components, BMW is the first carmaker which has developed quantitative management tools /1, 2/. These component related instruments enable designers in the product development phase to evaluate different component variations practice-oriented and with an ecological perspective in mind. In this endeavor, BMW is placing its bets on „intelligent lightweight construction”, i. e., the ecologically-economically best component solution.

Conventional engine coolant systems use primarily ethylene glycol with inorganic inhibitors. New systems based on organic acids are currently being introduced into the market. The primary advantage of these systems is non-depletion of the inhibitors, allowing extended service intervals, where the coolant is changed between 100,000 - 200,000 miles versus 30,000 - 50,000 miles with the current systems utilizing inorganic inhibitors. This benefits the consumer and the environment. Plastic components are widely used in coolant systems where radiator end tanks, water pump impellers, inlets, outlets, and thermostat housings can be polymeric. A study was conducted in which a number of engineering plastics were exposed to conventional and long life coolants at elevated temperatures and pressures to determine the effect of the coolant. The intent of the study was to provide insight into plastics which can withstand the hot acid environment of extended life coolants during usage.

Life Cycle Assessment (LCA) has emerged as an analytical tool to provide environmental information on a product or process through its life cycle. The cost of conducting a comprehensive LCA can be prohibitive and so “streamlining” approaches have been tested by practitioners. However, the more simple the model, the less detail and resolution it has, and this may undermine the reasons for undertaking the study. LCA complexity should be matched to the need to address environmental concerns. Certain stages of the LCA methodology are not well developed, (eg impact and improvement assessments). To overcome these difficulties, a Design for Environment (DFE) method has been used alongside LCA to provide a process by which real improvements can be initiated.