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A system was designed for controlling fuel injection and ignition timing for use on a port fuel injected, gas-fueled engine. Inputs required for the system include manifold absolute pressure, manifold air temperature, a once per revolution crankshaft pulse, a once per cycle camshaft pulse, and a relative encoder pulse train to determine crank angle. A prototype card installed in the computer contains counters and discrete logic which control the timing of ignition and injection events. High current drivers used to control the fuel injector solenoids and coil primary current are optically isolated from the computer by the use of fiber optic cables. The programming is done in QuickBASIC running in real time on a 25 MHz 80486 personal computer. The system was used to control a gas-fueled spark ignition engine at various conditions to map the torque versus air-fuel ratio and ignition timing. Each surface was mapped for a given fuel flow and speed.

This paper summarizes the state-of-the-art of various alternative fuel technologies for heavy-duty transit applications and compares them to conventional and “ clean” diesel engines. Alternative powerplants considered include compressed natural gas (CNG), liquefied natural gas (LNG), methanol, ethanol, liquefied petroleum gas (LPG), hydrogen, and several electric technologies. The various technologies are ranked according to emissions, operating and capital costs, safety, development status, driveability, and long term fuel supply. A simple spreadsheet-based rating system is presented; it not only provides a versatile, semi-quantitative way to rank technologies using both quantitative and qualitative information, but also helps identify critical areas which limit implementation for a given application. An example is given for urban transit buses.

Diesel fuel injection systems are operating at increasingly higher pressure (up to 250 MPa) with smaller clearances, making them more sensitive to diesel fuel contaminants. Most liquid particle counters have difficulty detecting particles <4 μm in diameter and are unable to distinguish between solid and semi-solid materials. The low conductivity of diesel fuel limits the use of the Coulter counter. This raises the need for a new method to characterize small (<4 μm) fuel contaminants. We propose and evaluate an aerosolization method for characterizing solid particulate matter in diesel fuel that can detect particles as small as 0.5 μm. The particle sizing and concentration performance of the method were calibrated and validated by the use of seed particles added to filtered diesel fuel. A size dependent correction method was developed to account for the preferential atomization and subsequent aerosol conditioning processes to obtain the liquid-borne particle concentration.

In many operating regimes, exhaust gas recirculation (EGR) while maintaining MBT spark timing improves cycle efficiency in SI engines. As the level of exhaust dilution is increased, the flame speed is reduced and the combustion rate is impaired. This leads to a drop in fuel economy as EGR rates are increased beyond the optimal level. To take advantage of the efficiency benefit of EGR without incurring the penalties of late combustion, a sensor which detects late combustion is tested. The signal from an ionization sensor placed near the exhaust port has been found to correlate to combustion which continues late into the expansion stroke. It may be possible to use the output from the ion sensor to maintain the EGR at the the optimum for fuel economy.

The correlations between the physical properties and autoignition parameters of several alternate fuels have been examined. The fuels are DF-2 and its blends with petroleum derived fuels, coal derived fuels, shale derived fuels, high aromatic naphtha sun-flower oils, methanol and ethanol. A total of eighteen existing correlations are discussed. An emphasis is made on the suitability of each of the correlations for the development of electronic controls for diesel engines when run on alternate fuels. A new correlation has been developed between the cetane number of the fuels and its kinematic viscosity and specific gravity.

Extended range electric vehicles (EREVs) are a potential solution for fossil fuel usage mitigation and on-road emissions reduction. The use of EREVs can be shown to yield significant fuel economy improvements when proper energy management strategies (EMSs) are employed. However, many in-use EREVs achieve only moderate fuel reduction compared to conventional vehicles due to the fact that their EMS is far from optimal. This paper focuses on in-use rule-based EMSs to improve the fuel efficiency of EREV last-mile delivery vehicles equipped with two-way Vehicle-to-Could (V2C) connectivity. The method uses previous vehicle data collected on actual delivery routes and machine learning methods to improve the fuel economy of future routes. The paper first introduces the main challenges of the project, such as inherent uncertainty in human driver behavior and in the roadway environment. Then, the framework of our practical physics-model guided data-driven approach is introduced.

A key challenge for the practical introduction of dual-fuel reactivity controlled compression ignition (RCCI) combustion modes in diesel engines is the requirement to store two fuels on-board. This work demonstrates that partially reforming diesel fuel into less reactive products is a promising method to allow RCCI to be implemented with a single stored fuel. Experiments were conducted using a thermally integrated reforming reactor in a reformed exhaust gas recirculation (R-EGR) configuration to achieve RCCI combustion using a light-duty diesel engine. The engine was operated at a low engine load and two reformed fuel percentages over ranges of exhaust gas recirculation (EGR) rate and main diesel fuel injection timing. Results show that RCCI-like emissions of NOx and soot were achieved load using the R-EGR configuration. It was also shown that complete fuel conversion in the reforming reactor is not necessary to achieve sufficiently low fuel reactivity for RCCI combustion.

Alcohols are examined as supplemental carbureted fuels for highspeed turbocharged diesels as typified by the White Motor/Waukesha F310 DBLT (6 cylinder, 310 cu. in.). Most of the work was with methanol; ethanol and isopropanol were compared at a few points. Fumigation (dual-fueling) with alcohol significantly reduced smoke and intake manifold temperature. These effects were largest at high load. Efficiency and HC emissions were essentially unchanged. Cylinder pressures and rise rates were examined for possible adverse effects on engine structure. The range of speed and load favorable to alcohol dual-fueling are such that, should alcohols become economically competitive as fuels, a practical duel-fuel system could be applied to existing diesel engines.

As part of an ongoing program to control the emissions of diesel-powered equipment used in underground mines, the U. S. Bureau of Mines evaluated exhaust emissions from a compression ignition engine using oxygenated diesel fuels and a diesel oxidation catalyst (DOC). The fuels include neat (100%) soy methyl ester (SME), and a blend of 30% SME (by volume) with 70% petroleum diesel fuel. A Caterpillar 3304 PCNA engine was tested for approximately 50 hours on each fuel. Compared with commercial low-sulfur diesel fuel (D2), neat SME increased volatile organic diesel particulate matter (DPM) but greatly decreased non-volatile DPM, for a net decrease in total DPM. The DOC further reduced volatile and total DPM NOx emissions were slightly reduced for the case of neat SME, but otherwise were not significantly affected. Peak brake power decreased 9% and brake specific fuel consumption increased 13 to 14% for the neat methyl soyate because of its lower energy content compared with D2.

A 1.9 liter Volkswagen TDI engine has been modified to accomodate the addition of hydrogen into the intake manifold via timed port fuel injection. Engine out particulate matter and the emissions of oxides of nitrogen were investigated. Two fuels,low sulfur diesel fuel (BP50) and soy methyl ester (SME) biodiesel (B99), were tested with supplemental hydrogen fueling. Three test conditions were selected to represent a range of engine operating modes. The tests were executed at 20, 40, and 60 % rated load with a constant engine speed o 1700 RPM. At each test condition the percentage of power from hydrogen energy was varied from 0 to 40 %. This corresponds to hydrogen flow rates ranging from 7 to 85 liters per minute. Particulate matter (PM) emissions were measured using a scaning mobility particle sizer (SMPS) and a two stage micro dilution system. Oxides of nitrogen were also monitored.

In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle auto-ignition phasing for low-load Low-Temperature Gasoline Combustion (LTGC), where highly dilute mixtures can lead to poor combustion stability. When mixed with fresh intake charge and fuel, these reformate streams can alter overall charge reactivity characteristics. The central issue remains large parasitic heat losses from the retention and compression of hot exhaust gases along with modest pumping losses that result from mixing hot NVO-period gases with the cooler intake charge. Accurate determination of total cycle energy utilization is complicated by the fact that NVO-period retained fuel energy is consumed during the subsequent main combustion period. For the present study, a full-cycle energy analysis was performed for a single-cylinder research engine undergoing LTGC with varying NVO auxiliary fueling rates and injection timing.

Previously, the authors have proposed a novel strategy called trajectory based combustion control for the free piston engine (FPE) where the shape of the piston trajectory between top and bottom dead centers is used as a control input to modulate the chemical kinetics of the fuel-air mixture inside the combustion chamber. It has been shown that in case of a hydraulic free piston engine (HFPE), using active motion control, the piston inside the combustion chamber can be forced to track any desired trajectory, despite the absence of a crankshaft, providing reliable starting and stable operation. This allows the use of optimized piston trajectory for every operating point which minimizes fuel consumption and emissions. In this work, this concept is extended to an electrical free piston engine (EFPE) as a modular power source.

Diesel exhaust particle number concentrations and size distributions, as well as gaseous and particulate mass emissions, were measured during steady-state tests on a US heavy-duty engine and a European passenger car engine. Two fuels were compared, namely a Fischer-Tropsch diesel fuel manufactured from natural gas, and a US D2 on-highway diesel fuel. With both engines, the Fischer-Tropsch fuel showed a considerable reduction in the number of particles formed by nucleation, when compared with the D2 fuel. At most test modes, particle number emissions were dominated by nucleation mode particles. Consequently, there were generally large reductions (up to 93%) in the total particle number emissions with the Fischer-Tropsch fuel. It is thought that the most probable cause for the reduction in nucleation mode particles is the negligible sulphur content of the Fischer-Tropsch fuel. In general, there were also reductions in all the regulated emissions with the Fischer-Tropsch fuel.

Many dual fuel technologies have been proposed for diesel engines. Implementing dual fuel modes can lead to emissions reductions or increased efficiency through using partially premixed combustion and fuel reactivity control. All dual fuel systems have the practical disadvantage that a secondary fuel storage and delivery system must be included. Reforming the primary diesel to a less reactive vaporized fuel on-board has potential to overcome this key disadvantage. Most previous research regarding on-board fuel reforming has been focused on producing significant quantities of hydrogen. However, only partially reforming the primary fuel is sufficient to vaporize and create a less volatile fuel that can be fumigated into an engine intake. At lower conversion efficiency and higher equivalence ratio, reforming reactors retain higher percentage of the inlet fuel’s heating value thus allowing for greater overall engine system efficiency.

Ethanol, used widely as a spark-ignition (SI) engine fuel, has seen minimal success as a compression ignition (CI) engine fuel. The lack of success of ethanol in CI engines is mainly due to ethanol's very low cetane number and its poor lubricity properties. Past researchers have utilized nearly pure ethanol in a CI engine by either increasing the compression ratio which requires extensive engine modification and/or using an expensive ignition improver. The objective of this work was to demonstrate the ability of a hydrogen port fuel injection (PFI) system to facilitate the combustion of ethanol in a CI engine. Non-denatured anhydrous ethanol, mixed with a lubricity additive, was used in a variable compression ratio CI engine. Testing was conducted by varying the amount of bottled hydrogen gas injected into the intake manifold via a PFI system. The hydrogen flowrates were varied from 0 - 10 slpm.

A biodiesel / petroleum fuel blend and practical low-cost methods of emission control were sought to obtain reductions in emissions from diesel generators. Little direct testing of biodiesel in diesel-powered electric generators has been done. Laboratory and field evaluations were conducted to determine the influence of using biodiesel on diesel exhaust emissions. B20 (20% biodiesel / 80% petroleum diesel) was chosen because of previously successful studies with this blend level, and there is evidence that the NOx emissions increase that result from using B20 can be controlled using existing technology. B85 was selected because it is a “high blend,” which promised to give a large decrease in PM at the expense of a larger increase in NOx than B20, but still within the range of control with existing technology. Charge-air cooling and a fuel additive were tested as NOx controls. For PM, CO, and HC reduction, a diesel oxidation catalyst (DOC) was evaluated.

Experiments were performed to measure the number-weighted particle size distributions emitted from a gasoline direct injection (GDI) engine. Measurements were made on a late model vehicle equipped with a direct injection spark ignition engine. The vehicle was placed on a chassis dynamometer, which was used to load the engine to road load at five different vehicle speeds ranging from 15 - 100 km/hr. Dilution of the exhaust aerosol was carried out using a two-stage dilution system in which the first stage dilution occurs as a free jet. Particle size distributions were measured using a TSI 3934 scanning mobility particle sizer. Generally speaking, the presence of the additives did not have a strong, consistent influence on the particle emissions from this engine. The polyether amine demonstrated a reduction in particle number concentration as compared to unadditized base fuel.

This report describes tests of a fuel additive in a medium-duty, high-swirl, direct-injection diesel engine. The additive was found to have little influence on general combustion performance or on NOx emissions. On the other hand, it had a profound effect on particulate emissions. This was most clear under high load where particle emissions are highest. Here, when the engine was switched from running on the base fuel to the additive treated fuel, particle emissions at first increased and then fell to levels about 40% lower (by particle volume) than those initially produced by the base fuel. The additive had a long lasting effect. After running with the additive for about 25 hours, emission levels with the base fuel were only slightly higher than those with the additive treated fuel. We believe that the additive action is associated with a combination of cleaning and surface conditioning. More work should be done to understand the relative importance of these two mechanisms.

This program used a 0.6 liter DI NA single cylinder diesel engine to study the influence of ferrocene as a fuel additive on particulate and NOx emissions and heat release rates. Previous Studies1,15 have shown efficiency and particulate emission benefits only after engine conditioning. Two engine configurations were tested: standard aluminum piston with normal engine deposits and a second test with the engine cleaned to “new engine condition”, but with the piston replaced with a thermal barrier coated piston. Particle concentration and size in roughly the 7.5 to 750 nm diameter range were measured with a condensation nucleus counter and an electrical aerosol analyzer. Heat release rates and IMEPs were calculated from in-cylinder pressure data. Particle number concentrations increased substantially when the 250 ppm dose was first started with both engine configuration, but decreased 30% to 50% with conditioning.

Negative Valve Overlap (NVO) is a potential control strategy for enabling Low-Temperature Gasoline Combustion (LTGC) at low loads. While the thermal effects of NVO fueling on main combustion are well-understood, the chemical effects of NVO in-cylinder fuel reforming have not been extensively studied. The objective of this work is to examine the effects of fuel molecular structure on NVO fuel reforming using gas sampling and detailed speciation by gas chromatography. Engine gas samples were collected from a single-cylinder research engine at the end of the NVO period using a custom dump-valve apparatus. Six fuel components were studied at two injection timings: (1) iso-octane, (2) n-heptane, (3) ethanol, (4) 1-hexene, (5) cyclohexane, and (6) toluene. All fuel components were studied neat except for toluene - toluene was blended with 18.9% nheptane by liquid volume to increase the fuel reactivity.