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A model is presented which incorporates the key mechanisms in the formation and reduction of unburned HC emissions from spark ignited engines. The model includes the effects of piston crevice volume, oil layer absorption / desorption, partial burns, and in-cylinder and exhaust port oxidation. The mechanism for the filling and emptying of the piston crevice takes into account the location of the flame front so that the flow of both burned gas and unburned gas is recognized. Oxidation of unburned fuel is calculated with a global, Arrhenius-type equation. A newly developed submodel is included which calculates the amount of unburned fuel to be added to the cylinder as a result of partial burns. At each crankangle, the submodel compares the rate of change of the burned gas volume to the rate of change of the cylinder volume.

The effects of engine operating conditions on the octane requirement and the resulting knock-limited output were studied on a single cylinder engine using production cylinder heads. A 4-valve cylinder head with port deactivation was used to study the effect of fuel octane, inlet air temperature, coolant temperature, air/fuel ratio, compression ratio and exhaust back pressure. The effect of the thermal environment was studied in more detail using separate cooling systems for the cylinder head and engine block on a 2-valve cylinder head. The results of this study compared closely with results found in the literature even though the engine and/or operating conditions were quite different in many cases.

The small-displacement direct-injection (DI) diesel engine is a prime candidate for future transportation needs because of its high thermal efficiency combined with near term production feasibility. Ford Motor Company and FEV Engine Technology, Inc. are working together with the US Department of Energy to develop a small displacement DI diesel engine that meets the key challenges of emissions, NVH, and power density. The targets for the engine are to meet ULEV emission standards while maintaining a best fuel consumption of 200g/kW-hr. The NVH performance goal is transparency with state-of-the-art, four-cylinder gasoline vehicles. Advanced features are required to meet the ambitious targets for this engine. Small-bore combustion systems enable the downsizing of the engine required for high fuel economy with the NVH advantages a four- cylinder has over a three-cylinder engine.

A structural ceramic diesel engine has the potential to provide low heat rejection and significant improvements in fuel economy. Analytical and experimental evaluations were conducted on the critical elements of this engine. The structural ceramic components, which included the cylinder, piston and pin, operated successfully in a single cylinder engine for over 100 hours. The potential for up to 8-11% improvement in indicated specific fuel consumption was projected when corrections for blow-by were applied. The ringless piston with gas squeeze film lubrication avoided the difficulty with liquid lubricants in the high temperature piston/cylinder area. The resulting reduction in friction was projected to provide an additional 15% improvement in brake specific fuel consumption for a multi-cylinder engine at light loads.

Naturally aspirated Homogeneous Charge Compression Ignition (HCCI) operational window is very limited due to inherent issues with combustion harshness. Load range can be extended for HCCI operation using a combination of intake boosting and cooled EGR. Significant range extension, up to 8bar NMEP at 1000RPM, was shown to be possible using these approaches in a single cylinder engine running residual trapping HCCI with 91RON fuel with a 12:1 compression ratio. Experimental results over the feasible speed / load range are presented in this paper for a negative valve overlap HCCI engine. Fuel efficiency advantage of HCCI was found to be around 15% at 2.62bar / 1500RPM over a comparable SI engine operating at the same compression ratio, and the benefit was reduced to about 5% (best scenario) as the load increased to 5bar at the same speed.

Development status and insight on a “research level” piezoelectric direct injection fuel injection system for prototype hydrogen Internal Combustion Engines (ICEs) is described. Practical experience accumulated from specialized material testing, bench testing and engine operation have helped steer research efforts on the fuel injection system. Recent results from a single cylinder engine are also presented, including demonstration of 45% peak brake thermal efficiency. Developing ICEs to utilize hydrogen can result in cost effective power plants that can potentially serve the needs of a long term hydrogen roadmap. Hydrogen direct injection provides many benefits including improved volumetric efficiency, robust combustion (avoidance of pre-ignition and backfire) and significant power density advantages relative to port-injected approaches with hydrogen ICEs.

Modern four-valve engines are running at ever higher compression ratios in order to improve fuel efficiency. Hotter cylinder bores also can produce increased fuel economy by decreasing friction due to less viscous oil layers. In this study changes in compression ratio and coolant temperature were investigated to quantify their effect on exhaust emissions. Tests were run on a single cylinder research engine with a port-deactivated 4-valve combustion chamber. Two compression ratios (9.15:1 and 10.0:1) were studied at three air/fuel ratios (12.5, 14.6 and 16.5) at a part load condition (1500 rpm, 3.8 bar IMEP). The effect of coolant temperature (66 °C and 108°C) was studied at the higher compression ratio. The exhaust was sampled and analyzed for both total and speciated hydrocarbons. The speciation analysis provided concentration data for hydrocarbons present in the exhaust containing twelve or fewer carbon atoms.

The development of a plasma jet ignition system based on use of plasma jet spark plugs is described. Particular attention is given to systems design for automotive application. Design data for plasma jet spark plugs are given. Tests on a 37.3 CID single cylinder engine with vapor tank fuel metering indicate that plasma jet ignition produces extension of the lean misfire limit, reduction of ignition delay and burn time, higher NO, and increased torque compared to conventional ignition. Discussion of the electrical power requirements of a plasma jet ignition system is given. Operating experience for a four cylinder 2.3L test vehicle is described.

Injecting liquid water into a fuel/air charge is a means to reduce NOx emissions. Such strategies are particularly important to hydrogen internal combustion engines, as engine performance (e.g., maximum load) can be limited by regulatory limits on NOx. Experiments were conducted in this study to quantify the effects of direct injection of water into the combustion chamber of a port-fueled, hydrogen IC engine. The effects of DI water injection on NOx emissions, load, and engine efficiency were determined for a broad range of water injection timing. The amount of water injected was varied, and the results were compared with baseline data where no water injection was used. Water injection was a very effective means to reduce NOx emissions. Direct injection of water into the cylinder reduced NOx emissions by 95% with an 8% fuel consumption penalty, and NOx emissions were reduced by 85% without any fuel consumption penalty.

Absorption of fuel in engine oil layers has been shown to be a possible source of hydrocarbon (HC) emissions from spark-ignited engines. However, the magnitude of this source in a normally operating engine has not been determined unambiguously. In these experiments, a series of n-alkanes of widely different solubility (n-hexane through undecane) was added (1.5 wt % each) to a Base gasoline (CA Phase 2). Steady-state experiments were carried out at two coolant temperatures (339 and 380 K) using a single-cylinder engine with the combustion chamber of a production V-8. Both total and speciated engine-out HC emissions were measured. The emissions indices of the heavier dopants did not increase relative to hexane at either coolant temperature.

Sector mesh modeling is the dominant computational approach for combustion system design optimization. The aim of this work is to quantify the errors descending from the sector mesh approach through three geometric modeling approaches to an optical diesel engine. A full engine geometry mesh is created, including valves and intake and exhaust ports and runners, and a full-cycle flow simulation is performed until fired TDC. Next, an axisymmetric sector cylinder mesh is initialized with homogeneous bulk in-cylinder initial conditions initialized from the full-cycle simulation. Finally, a 360-degree azimuthal mesh of the cylinder is initialized with flow and thermodynamics fields at IVC mapped from the full engine geometry using a conservative interpolation approach. A study of the in-cylinder flow features until TDC showed that the geometric features on the cylinder head (valve tilt and protrusion into the combustion chamber, valve recesses) have a large impact on flow complexity.

An ionization probe head gasket (to IPHG) was used to investigate flame development in a 2.0L I4 engine with two in-cylinder fluid motions. A new technique was developed to display accurate flame contours at 2%, 10% and 50% mass fraction burned crank angles using the measurements of flame arrival time from the ion probes in conjunction with cycle simulations. The flame arrival and burn rate information is used to scale the relationship between flame radius and mass fraction burned from the cycle simulation to create accurate contours of the flame for each cycle. The tumbling motion inside the combustion chamber produced by the production intake ports convected the flame towards the exhaust side of the chamber. The geometry of the flame development was relatively unaffected by changes in speed and load.

Currently most automotive manufacturers calibrate for rich air/fuel ratios at wide open throttle which produces lower exhaust gas temperatures. Future federal emissions regulations may require less enrichment under these conditions. This study was undertaken to address the question of what happens to engine-out hydrocarbon emissions with different air/fuel ratios at wide open throttle. Tests were run on a single cylinder research engine with a two valve combustion chamber at a compression ratio of 9:1. The test matrix included three air/fuel ratios (10.5, 12.5 and 14.5) and two speeds (1500 and 3000 rpm) at wide open throttle as well as three air/fuel ratios (12.5, 14.6 and 16.5) at a part load condition (1500 rpm, 3.8 bar IMEP). The exhaust was sampled and analyzed for both total and speciated hydrocarbons. The speciation analysis provided concentration data for hydrocarbons present in the exhaust containing twelve or fewer carbon atoms.

Validation of the Ford General Engine SIMulation program (GESIM) with measured firing data from a modified single cylinder Ricardo HYDRA research engine is described. GESIM predictions for peak cylinder pressure and burn duration are compared to test results at idle operating conditions over a wide range of valve overlap. The calibration of GESIM was determined using data from only one representative world-wide operating point and left unchanged for the remainder of the study. Valve overlap was varied by as much as 36° from its base setting. In most cases, agreement between model and data was within the accuracy of the measurements. A cycle simulation computer model provides the researcher with an invaluable tool for acquiring insight into the thermodynamic and fluid mechanical processes occurring in the cylinder of an internal combustion engine.

In 1981, Ford Motor Company introduced a new family of fuel efficient four cylinder engines world wide. These engines, based on a compound valve arrangement in a hemispherical combustion chamber, were specifically designed for installation in light weight front-wheel-drive vehicles. Ford Research efforts were integrated with the resources of Ford U.S. and Ford of Europe to design and develop the engine in a compressed time frame. The technical and organizational efforts to accomplish this task, as well as, the design and development are discussed.