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Diesel particulate filters are designed to reduce the mass emissions of diesel particulate matter and have been proven to be effective in this respect. Not much is known, however, about their effects on other unregulated chemical species. This study utilized source dilution sampling techniques to evaluate the effects of a catalyzed diesel particulate filter on a wide spectrum of chemical emissions from a heavy-duty diesel engine. The species analyzed included both criteria and unregulated compounds such as particulate matter (PM), carbon monoxide (CO), hydrocarbons (HC), inorganic ions, trace metallic compounds, elemental and organic carbon (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and other organic compounds. Results showed a significant reduction for the emissions of PM mass, CO, HC, metals, EC, OC, and PAHs.

The effect of the ring pack storage mechanism on the hydrocarbon (HC) emissions from an air-cooled utility engine has been studied using a simplified ring pack model. Tests were performed for a range of engine load, two engine speeds, varied air-fuel ratio and with a fixed ignition timing using a homogeneous, pre-vaporized fuel mixture system. The integrated mass of HC leaving the crevices from the end of combustion (the crank angle that the cumulative burn fraction reached 90%) to exhaust valve closing was taken to represent the potential contribution of the ring pack to the overall HC emissions; post-oxidation in the cylinder will consume some of this mass. Time-resolved exhaust HC concentration measurements were also performed, and the instantaneous exhaust HC mass flow rate was determined using the measured exhaust and cylinder pressure.

The ability to make fully resolved turbulent scalar field measurements has been demonstrated in an internal combustion engine using one-dimensional fluorobenzene fluorescence measurements. Data were acquired during the intake stroke in a motored engine that had been modified such that each intake valve was fed independently, and one of the two intake streams was seeded with the fluorescent tracer. The scalar energy spectra displayed a significant inertial subrange that had a −5/3 wavenumber power dependence. The scalar dissipation spectra were found to extend in the high-wavenumber regime, to where the magnitude was more than two decades below the peak value, which indicates that for all practical purposes the measurements faithfully represent all of the scalar dissipation in the flow.

The focus of this paper is to discuss the modeling and control of intake plenum pressure on the Powertrain Control Research Laboratory's (PCRL) Single-Cylinder Engine (SCE) transient test system using a patented device known as the Intake Air Simulator (IAS), which dynamically controls the intake plenum pressure, and, subsequently, the instantaneous airflow into the cylinder. The IAS exists as just one of many devices that the PCRL uses to control the dynamic boundary conditions of its SCE transient test system to make it “think” and operate as though it were part of a Multi-Cylinder Engine (MCE) test system. The model described in this paper will be used to design a second generation of this device that utilizes both continuously and discretely actuating valves working in parallel.

Although turbocharging can extend the high load limit of low temperature combustion (LTC) strategies such as reactivity controlled compression ignition (RCCI), the low exhaust enthalpy prevalent in these strategies necessitates the use of high exhaust pressures for improving turbocharger efficiency, causing high pumping losses and poor fuel economy. To mitigate these pumping losses, the divided exhaust period (DEP) concept is proposed. In this concept, the exhaust gas is directed to two separate manifolds: the blowdown manifold which is connected to the turbocharger and the scavenging manifold that bypasses the turbocharger. By separately actuating the exhaust valves using variable valve actuation, the exhaust flow is split between two manifolds, thereby reducing the overall engine backpressure and lowering pumping losses. In this paper, results from zero-dimensional and one-dimensional simulations of a multicylinder RCCI light-duty engine equipped with DEP are presented.

A direct calibration has been performed on laser-induced fluorescence measurements of the oil film in a single cylinder air-cooled research engine by simultaneously measuring the minimum oil film thickness by the capacitance technique. At the minimum oil film thickness the capacitance technique provides an accurate measure of the ring-wall distance, and this value is used as a reference for the photomultiplier voltage, giving a calibration coefficient. This calibration coefficient directly accounts for the effect of temperature on the fluorescent properties of the constituents of the oil which are photoactive. The inability to accurately know the temperature of the oil has limited the utility of off-engine calibration techniques. Data are presented for the engine under motoring conditions at speeds from 800 - 2400 rpm and under varying throttle positions.

An experimental study was performed to investigate diesel particulate filter (DPF) performance during filtration with the use of real-time measurement equipment. Three operating conditions of a single-cylinder 2.3-liter D.I. heavy-duty diesel engine were selected to generate distinct types of diesel particulate matter (PM) in terms of chemical composition, concentration, and size distribution. Four substrates, with a range of geometric and physical parameters, were studied to observe the effect on filtration characteristics. Real-time filtration performance indicators such as pressure drop and filtration efficiency were investigated using real-time PM size distribution and a mass analyzer. Types of filtration efficiency included: mass-based, number-based, and fractional (based on particle diameter). In addition, time integrated measurements were taken with a Rupprecht & Patashnick Tapered Element Oscillating Microbalance (TEOM), Teflon and quartz filters.

The fuel film thickness resulting from diesel fuel spray impingement was measured in a chamber at conditions representative of early injection timings used for low temperature diesel combustion. The adhered fuel volume and the radial distribution of the film thickness are presented. Fuel was injected normal to the impingement surface at ambient temperatures of 353 K, 426 K and 500 K, with densities of 10 kg/m3 and 25 kg/m3. Two injectors, with nozzle diameters of 100 μm and 120 μm, were investigated. The results show that the fuel film volume was strongly affected by the ambient temperature, but was minimally affected by the ambient density. The peak fuel film thickness and the film radius were found to increase with decreased temperature. The fuel film was found to be circular in shape, with an inner region of nearly constant thickness. The major difference observed with temperature was a decrease in the radial extent of the film.

Three distinct types of diesel particulate matter (PM) are generated in selected engine operating conditions of a single-cylinder heavy-duty diesel engine. The three types of PM are trapped using typical Cordierite diesel particulate filters (DPF) with different washcoat formulations and a commercial Silicon-Carbide DPF. Two systems, an external electric furnace and an in-situ burner, were used for regeneration. Furnace regeneration experiments allow the collected PM to be classified into two categories depending on oxidation mechanism: PM that is affected by the catalyst and PM that is oxidized by a purely thermal mechanism. The two PM categories prove to contribute differently to pressure drop and transient filtration efficiency during in-situ regeneration.

A four valve controller and electronic control circuits were developed to control the displacement of hydrostatic pump/motors (P/M's) utilized in an automobile with a hydrostatic transmission and hydropneumatic accumulator energy storage. Performance of the control system was evaluated. The controller uses four high-speed, two-way, single-stage poppet valves, functioning in the same manner as a 4-way, 3-position spool valve. Two such systems were used to control the displacement of two P/Ms, each system driving a front wheel of the vehicle. The valves were controlled electronically by a distributed-control dead-band circuit and valve driver boards. Testing showed that the control system's time response satisified driving demand needs, but that the control system's error was slightly larger than desired. This may lead to complications in some of the vehicle's operating modes.

Optimal fuel injection strategies are obtained with a micro-genetic algorithm and an adaptive gradient method for a nonroad, medium-speed DI diesel engine equipped with a multi-orifice, asynchronous fuel injection system. The gradient optimization utilizes a fast-converging backtracking algorithm and an adaptive cost function which is based on the penalty method, where the penalty coefficient is increased after every line search. The micro-genetic algorithm uses parameter combinations of the best two individuals in each generation until a local convergence is achieved, and then generates a random population to continue the global search. The optimizations have been performed for a two pulse fuel injection strategy where the optimization parameters are the injection timings and the nozzle orifice diameters.

An investigation of the effect of microflow machining on the spray characteristics of diesel injectors was undertaken. A collection of four VCO injector tips were tested prior to and after an abrasive flow process using a high viscosity media. The injector nozzles were tested on a spray fixture. Rate of injection measurements and high-speed digital images were used for the quantification of the air entrainment rate. Comparisons of the spray characteristics and A/F ratios were made for conditions of before and after the abrasive flow process. Results showed a significant decrease in the injection-to-injection variability and improvement of the spray symmetry. A link between the quantity of air entrained and potential differences in spray plume internal chemical composition and temperature is proposed via equilibrium calculations.

Micro-machined planar orifice nozzles have been developed and used with commercially produced diesel injection systems. Such a system may have the capability to improve the spray characteristics in DI diesel engines. The availability of a MEMS (Micro-Electro-Mechanical-Systems) processing sequence supported the construction of micro-planar orifice nozzles, and micro-systems technology was also employed in our macro-instrumentation. To demonstrate this process, fourteen MEMS nozzles were fabricated with deep X-ray lithography and electroplating technology. The circular orifice diameters were varied from 40 to 260 microns and the number of orifices varied from one to 169. Three plates with non-circular orifices were also fabricated to examine the effect of orifice shape on spray characteristics. These nozzles were then attached to commercial injectors and the associated injection systems were used for the spray experiments.

Using a low-speed high-torque (LSHT) pump/motor to provide the speed range and torque for a hydrostatic automobile offers a number of advantages over using a high-speed low-torque pump/motor, combined with a gear reducer. However, there appear to be no LSHT units commercially available that have true variable displacement capability. Because of this void, a variable displacement pump/motor has been designed and built that could provide a direct drive for each wheel of a hydrostatic automobile. The unit uses some components such as the cylinder block, piston and modified rotating case from a commercially available radial piston pump/motor. Initial preliminary testing of the pump/motor indicates that it has good efficiency and performance characteristics, and, with further development should be very attractive for automotive use. This paper focuses on the design and kinematics of the device.

This paper describes how a blend of silicon polymers, mixed with the right combination of fillers, enables the production of durable rubber IC engine head and exhaust gaskets. The resin blend, when mixed with glass fiber reinforcement, produces a liquid sealant suitable for exhaust gasket applications. The exhaust sealant and laminate head gaskets were tested on Ford 460 truck engines at Jasper Engine Company and completed more than 5,000 hours of durability testing without incident. Fabric reinforced polymer (FRP) head and exhaust gaskets can be laser cut from molded laminates, creating a ceramic glass-sealed edge. Thermogravimetric scans of typical gasket laminate material reveal an 88%-yield at 1000°C. FRP head gaskets also enable the cost-effective production of multiple spark ignition (MSI) head gaskets.

A single cylinder, Cummins NH, direct-injection, diesel engine has been operated in order to evaluate the effects of aromatic content and aromatic structure on diesel engine particulates. Results from three fuels are shown. The first fuel, a low sulfur Chevron diesel fuel was used as a base fuel for comparison. The other fuels consisted of the base fuel and 10% by volume of 1-2-3-4 tetrahydronaphthalene (tetralin) a single-ring aromatic and naphthalene, a double-ring aromatic. The fuels were chosen to vary aromatic content and structure while minimizing differences in boiling points and cetane number. Measurements included exhaust particulates using a mini-dilution tunnel, exhaust emissions including THC, CO2, NO/NOx, O2, injection timing, two-color radiation, soluble organic fraction, and cylinder pressure. Particulate measurements were found to be sensitive to temperature and flow conditions in the mini-dilution tunnel and exhaust system.

Due to concerns regarding pollutant and CO2 emissions, advanced combustion modes that can simultaneously reduce exhaust emissions and improve thermal efficiency have been widely investigated. The main characteristic of the new combustion strategies, such as HCCI and LTC, is that the formation of a homogenous mixture or a controllable stratified mixture is required prior to ignition. The major issue with these approaches is the lack of a direct method for the control of ignition timing and combustion rate, which can be only indirectly controlled using high EGR rates and/or lean mixtures. Homogeneous Charge Progressive Combustion (HCPC) is based on the split-cycle principle. Intake and compression phases are performed in a reciprocating external compressor, which drives the air into the combustor cylinder during the combustion process, through a transfer duct. A transfer valve is positioned between the compressor cylinder and the transfer duct.

Fuel-borne catalysts (FBC) have demonstrated efficacy as an important strategy for integrated diesel emission control. The research summarized herein provides new methodologies for the characterization of engine-out speciated emissions. These analytical tools provide new insights on the mode of action and chemical forms of metal emissions arising from use of a platinum and cerium based commercial FBC, both with and without a catalyzed diesel particulate filter. Characterization efforts addressed metal solubility (water, methanol and dichloromethane) and particle size and charge of the target species in the water and solvent extracts. Platinum and cerium species were quantified using state-of-the-art high resolution plasma mass spectrometry. Liquid-chromatography-triple quad mass spectrometry techniques were developed to quantify potential parent Pt-FBC in the PM extracts. Speciation was examined for emissions from cold and warm engine cycles collected from an engine dynamometer.

An experimental investigation of turbulent flow patterns in a scale model of a high pressure diesel fuel injector nozzle has been conducted. Instantaneous velocity measurements were made in a 50X transparent model of one hole of the injector nozzle using an Aerometrics Phase Doppler Particle Analyzer (PDPA) in the velocity mode. Length to diameter ratio (L/D) values of 1.3, 2.4, 4.9, and 7.7 and inlet radius to diameter ratio (R/D) values of approximately 0 and 0.3 were investigated. Two steady flow average Reynolds numbers (10,500 and 13,300), analogous to fuel injection velocities and sac pressures of approximately 320 and 405 m/s and 67 and 107 MPa (10,000 and 16,000 psi), were investigated. The axial progression of mean and root mean square (rms) axial velocities was obtained for both sharp and rounded inlet conditions and varying L/D. The discharge coefficient was also calculated for each geometry.

Intake port and cylinder flow have been modeled for a dual intake valve diesel engine. A block structured grid was used to represent the complex geometry of the intake port, valves, and cylinder. The calculations were made using a pre-release version of the KIVA-3 code developed at Los Alamos National Laboratories. Both steady flow-bench and unsteady intake calculations were made. In the flow bench configuration, the valves were stationary in a fully open position and pressure boundary conditions were implemented at the domain inlet and outlet. Detailed structure of the in-cylinder flow field set up by the intake flow was studied. Three dimensional particle trace streamlines reveal a complex flow structure that is not readily described by global parameters such as swirl or tumble. Streamlines constrained to lie in planes normal to the cylinder axis show dual vortical structures, which originated at the valves, merging into a single structure downstream.