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It is desirable to predict the cold weather driveability performance of fuels by means of an index based on simple measurements such as the ASTM distillation curve. In the past, several such indices have been proposed from the analysis of vehicle test results. In contrast, this paper describes how a driveability index can be derived from first principles - namely, the physics of fuel vapour formation. A number of present and proposed driveability indices were evaluated by comparing the way they correlate with the calculated enthalpy requirement of fuels. It is concluded that E100+E150 best meets the need for a simple index and is robust across a range of air/fuel ratios.

Certain polycyclic aromatic hydrocarbons (PAH) are carcinogenic and discussion will commence shortly in Europe on the development of an appropriate ambient air quality standard. With this proposed standard in mind, it is important to understand the contribution made by different emission sources to ambient PAH; this paper addresses only the contribution from automotive exhaust emissions. Methods for the sampling and analysis of particulate bound PAH from exhaust emissions, although not standardised, are well established. Vapour phase PAH however, are often neglected and need to be accurately quantified to assess the total contribution made by automotive sources to anthropogenic PAH emissions to the atmosphere. This paper describes the development of a technique applicable to the simultaneous collection and measurement of both vapour phase and particulate bound PAH in exhaust emissions. The final method selection focused on a filter/adsorbent trap sampler.

Traditional approaches to pollution control have been to develop benign non-polluting processes or to abate emissions at the tailpipe or stack before emitting to the atmosphere. A new technology called PremAir®* Catalyst Systems takes a different approach and directly reduces ambient ground level ozone. This technology can be applied to both mobile and stationary applications. For automotive applications, the new system involves placing a catalytic coating on the car's radiator or air conditioner condenser. As air passes over the radiator or condenser, the catalyst converts the ozone into oxygen. Three Volvo vehicles with a catalyst coating on the radiator were tested on the road during the 1997 summer ozone season in southern California to assess performance. Studies were also conducted in Volvo's laboratory to determine the effect of the catalyst coating on the radiator's performance with regard to corrosion, heat transfer and pressure drop.

Fouling spark plugs on an internal combustion engine is greatly influenced by cold temperatures, especially at older assembly plants where the vehicle is moved several times because of discontinuities in the assembly line. To transition the vehicle, the operator starts the vehicle, places it in drive and accelerates rapidly, then shuts the vehicle off. This process only lasts ten to fifteen seconds and does not allow the spark plug or engine to get to a high enough operating temperature to evaporate away the fuel, which fouls the spark plugs. A spark plug fouling test is devised and is used to investigate which properties of fuel play the most significant anti-fouling role. Some additives believed to have anti-fouling properties will also be investigated to determine their significance. The anti-fouling fuel will then be implemented at the assembly plants.

The Coordinating Research Council conducted a program to measure the effect of fuel sulfur on emissions from California Low Emission Vehicles (LEVs). Twelve vehicles, two each from six production LEV models, were tested using low mileage as-received catalysts and catalysts aged to 100k by each vehicle manufacturer using “rapid-aging” procedures. There were seven test fuels: five conventional fuels with sulfur ranging from 30 to 630 ppm, and two California reformulated gasoline (RFG) with sulfur of 30 and 150 ppm. Reducing fuel sulfur produced statistically significant reductions in LEV fleet emissions of NMHC, NOx and CO. Comparing conventional fuel and California RFG at the same sulfur level: California RFG had lower NMHC and NOx emissions and higher CO emissions, but only some NMHC and NOx differences and none of the CO differences between conventional and California RFG were statistically significant.

In the current investigation, the authors identified conditions under which increased in-cylinder turbulence can be used to improve diesel emissions. Two separate regimes of engine operation were identified; one in which combustion was constrained by mixing and one in which it was not. These regimes were dubbed under-mixed and over-mixed, respectively. It was found that increasing mixing in the former regime had a profound effect on soot emission. Fuel injection characteristics were found to be extremely important in determining the point at which mixing became inadequate. In addition, the ratio of the fuel injection momentum flux relative to that of the gas injection was found to be important in determining how increasing mixing would effect soot emissions.

The traditional diesel engine suffers from high emission levels of nitrogen oxide and particulate matter. A new injection concept has therefore been developed and investigated. To enhance the air-fuel mixing process and avoid local concentration of fuel, the injection direction of each spray is varied during the injection event. This was achieved by rotating the injector. In this test, the rotational speed was 1700 rpm. On a six-cylinder engine, one cylinder was equipped with the new injector and exhaust gases were sampled with a new type of valve, integrated in the exhaust-valve stem of the affected cylinder. Tests show that the combustion is significantly affected by the rotating injection. The impact of the rotating injection on smoke, emissions and heat release was repeatable but dependent on loadpoint. No universal trend over all loadpoints was found. NO levels were mostly lowered but for smoke and CO, both lower and higher levels than without rotation were encountered.

This paper describes the combustion optimizations of heavy-duty diesel engines for the anticipated future emissions regulations by means of an electronically controlled common rail injection system. Tests were conducted on a turbocharged and aftercooled (TCA) prototype heavy-duty diesel engine. To improve both NOx-fuel consumption and NOx-PM trade-offs, fuel injection characteristics including injection timing, injection pressure, pilot injection quantity, and injection interval on emissions and engine performances were explored. Then intake swirl ratio and combustion chamber geometry were modified to optimize air-fuel mixing and to emphasize the pilot injection effects. Finally, for further NOx reductions, the potentials of the combined use of EGR and pilot injection were experimentally examined. The results showed that the NOx-fuel consumption trade-off is improved by an optimum swirl ratio and combustion chamber geometry as well as by a new pilot concept.

A variable swirl intake port system for 4 valves/cylinder direct injection diesel engines was developed. This system combines two mutually independent intake ports, one of which is a helical port for generating an ultra-high swirl ratio and the other is a tangential port for generating a low swirl ratio. The tangential port incorporates a swirl control valve that controls the swirl ratio by varying the flow rate. To investigate the performance of the intake port system, steady-state flow tests were conducted in parallel with three-dimensional computations. In conducting the steady-state flow tests, it was found that a paddle wheel flow sensor was not suitable for evaluating the characteristics of the high-swirl port and that it was necessary to use an impulse swirl flow meter.

This paper is a direct continuation of a previous study that addressed the performance and design of a variable compression engine, the Alvar-Cycle Engine [1]. The earlier study was presented at the SAE International Conference and Exposition in Detroit during February 23-26, 1998 as SAE paper 981027. In the present paper test results from a single cylinder prototype are reviewed and compared with a similar conventional engine. Efficiency and emissions are shown as function of speed, load, and compression ratio. The influence of residual gas on knock characteristics is shown. The potential for high power density through heavy supercharging is analyzed.

A single-cylinder direct-injection (DI) Diesel engine (Cummins 903) equipped with a new laboratory-built electronically controlled high injection pressure fuel unit (HIP) was studied in order to evaluate design strategies for achieving a high power density (HPD) compression ignition (CI) engine. In performing the present parametric study of engine response to design changes, the HIP was designed to deliver injection pressures variable to over 210 MPa (30,625psi). Among other parameters investigated for the analysis of the I-IPD DI-CI engine with an HIP were the air/fuel ratio ranging from 18 to 36, and intake air temperature as high as 205°C (400°F). The high temperatures in the latter were considered in order to evaluate combustion reactions expected in an uncooled (or low-heat-rejection) engine for a HPD, which operates without cooling the cylinder. Engine measurements from the study include: indicated mean effective pressure, fuel consumption, and smoke emissions.

Chemiluminescence imaging has been applied to a parametric investigation of diesel autoignition. Time-resolved images of the natural light emission were made in an optically accessible DI diesel engine of the heavy-duty size class using an intensified CCD video camera. Measurements were obtained at a base operating condition, corresponding to a motored TDC temperature and density of 992 K and 16.6 kg/m3, and for TDC temperatures and densities above and below these values. Data were taken with a 42.5 cetane number blend of the diesel reference fuels for all conditions, and measurements were also made with no. 2 diesel fuel (D2) at the base condition. For each condition, temporal sequences of images were acquired from the time of first detectable chemiluminescence up through fully sooting combustion, and the images were analyzed to obtain quantitative measurements of the average emission intensity.

In this paper, the authors proposed a method for on line rapid estimation of power performance and mechanical losses of engines. The power and mechanical losses of an engine are estimated based on the principle of inertia acceleration-deceleration and the measurement of transient crankshaft speed variation that were taken from the updated data acquisition processing measurement system. The calculation, feature and function of the on line rapid estimation methods are described. The derived power and mechanical losses using this method were compared to the results by dynamometer. The experimental equipment as well as the results are illustrated. Using this method, the characteristic mechanical efficiency of the engine as well as the cylinder's relative compression[1][2], starting and acceleration performance could also be estimated easily.

An innovative rotary engine uses a rotor that executes pendulum-like oscillatory rotation. This is converted into uniform rotation of the drive shaft by a simple mechanism. The engine also employs parameter resonance. The new design is compact and lightweight. Economy of fuel and lubricants, reduced air pollution, simpler and cheaper fabrication, lower levels of noise, easier maintenance are among its advantages over the Wankel rotary engine and the Otto piston engine.

A conceptual understanding of modularity in internal combustion engines (defined as design, operation, and sensing on an individual cylinder basis) is presented. Three fundamental modular concepts are identified. These are dissimilar component sizing and operation, component deactivation, and direct sensing. The implementation of these concepts in spark ignition internal combustion engines is presented. Several modular approaches are reviewed with respect to breathing, fueling, power generation, and sensing. These include dissimilar orientation, geometry, and activation of multiple induction runners, partial or total disablement of valves through direct or indirect means, dissimilar fueling of individual cylinders, skipping the combustion event of one or more cylinders, deactivation of dissimilar individual cylinders or a group of cylinders, and individual cylinder gas pressure and mixture strength sensing.

This paper documents an extensive study aimed at a better understanding of the peculiarities and performance of crankshaft mounted gerotor pumps for IC engines lubrication. At different extents, the modelling, simulation and testing of a specific unit are all considered. More emphasis, at the modelling phase, is dedicated to the physical and mathematical description of the flow losses mechanisms; the often intricate aspects of kinematics being deliberately left aside. The pressure relief valve is analysed at a considerable extent as is the modelling of the working fluid, a typically aerated subsystem in such applications. Simulation is grounded on AMESim, a relatively novel tool in the fluid power domain, that proves effective and compliant with user deeds and objectives. Testing, at steady-state conditions, forms the basis for the pro!gressive tuning of the simulation model and provides significant insight into this type of volumetric pump.

Linear, crankless, internal combustion engines may find application in the generation of electrical power without the need to convert linear to rotary motion. The elimination of the connecting rod and crankshaft would significantly improve the efficiency of the engine and the reduced weight and cost is an added advantage. The case of two opposed cylinders, with two pistons linked by a solid rod, was considered for idealized modeling. The piston/rod assembly was considered to oscillate with only constant frictional drag. The Otto cycle was used to model efficiency, and this in turn determined compression ratio. Dimensionless groups governing the engine working were identified and used in formulating a description of the engine behavior. Two-stroke operation was assumed. Velocity and position can be related analytically to yield a phase plot.

The exhaust noise of a two-cylinder four-stroke diesel engine was experimentally investigated in order to examine the predictability of the exhaust noise to be reduced by a feedforward active control system. Special attention has been paid to the low frequency characteristics of the exhaust noise as low frequency noise is difficult to reduce with a conventional muffler but effective to control by active control technique. The periodicity of the exhaust noise was examined with the ensemble-average and ensemble-standard deviation of the exhaust pressure signals. The results showed that the exhaust noise investigated was basically quasi-periodic and its variation between cycles was acceptable with an adaptive control algorithm. The properties of the exhaust pressure in low frequency domain were analyzed with the spectra of the exhaust noise pressure.

The development of a modern internal combustion engine can be characterized by three main trends: durability increase, emission reduction, and fuel economy improvement. Ring pack design addresses all of these issues. The ring behavior affects the blow-by past the ring pack, the oil film left on the cylinder liner, the friction force between the liner and the ring, and the wear of the ring and the cylinder liner. In order to predict these phenomena, the prediction of inter-ring gas flow and ring behavior, especially ring motion and ring twist about ring centroid, is needed. This paper presents the results of the modeling of 3-dimensional ring twist and its influence on ring performance and blow-by. The TWIST program includes a 3-dimensional beam model of a piston ring.

In this paper, a generic methodology is proposed to simulate the static and dynamic responses of a SI gas engine. The predicted simulation of engine performances is based on a one zone thermodynamic model. The turbocharger is modeled by using polytropic coefficients, the intercooler by its efficiency. The Ventury effect carburetor model is based on physic properties and the butterfly valve model uses a classical approach. A comparison between the simulation and experimental results is realized in terms of static and dynamic performances in closed loop. Comparisons with actual data obtained on a 210 kW engine shows that the maximum error is less than 5 %.