Charles A. Amann

Diesel particulates--what they are and why

The diesel passenger car offers a substantial advantage in fuel economy over its gasoline-powered counterpart, but the long-range future of the diesel in this application is threatened by future federal standards on exhaust particular emissions. These particulates are primarily combustion-generated carbonaceous soot in combination with a solvent-extractable hydrocarbon fraction. Particulate production involves an incompletely understood series of phenomena that includes nucleation, surface growth, agglomeration, dehydrogenation, oxidation, and adsorption and condensation of gaseous hydrocarbons. The contemporary state of understanding of these events is reviewed as they apply to the passenger-car diesel engine.

THE GT-225--AN ENGINE FOR PASSENGER-CAR GAS-TURBINE RESEARCH

The intensive search for an alternative low-emission powerplant for passenger cars has led to a re-evaluation of the gas turbine for this type of service. The GT-225 engine was designed as a research tool. Vehicle tests of the engine fitted with a low-emission combustor demonstrated the following emissions: 0.11 g/km (0.18 g/mile) HC; 1.2 g/km (2.0 g/mile) CO; and 0.23 g/km (0.38 g/mile) NOx. In addition, fuel economy competitive with that of conventional passenger cars at turnpike speeds, substantially improved throttle response in comparison with earlier heavy-duty turbine engines and engine braking equal to that provided by the typical powertrain in todays cars were demonstrated. /GMRL/

Diesel for Passenger-Car Application Exploratory Study of the Low-Heat-Rejection Diesel for Passenger-Car Application

Eliminating the conventional liquid cooling system of a diesel engine to conserve energy normally rejected to that heat sink offers promise as a means for improving fuel economy. Such low-heat-rejection (LHR) diesels have generally been advanced for heavy-duty vehicles. In this study, application of the concept is analyzed for a light-duty indirect-injection diesel of the type used in passenger cars. The naturally aspirated LHR diesel is found to offer no fuel economy advantage, principally because of the deteriorated volumetric efficiency arising from hot cylinder walls. It is found that most of the energy conserved by deleting the cooling system is diverted to the exhaust gas. Methods examined for recovering the lost volumetric efficiency and/or harnessing the increased energy content of the exhaust include supercharging, adding a bottoming cycle, and combining the diesel with turbomachinery. The latter option is judged superior for the passenger-car application.

A perspective of reciprocating-engine diagnostics without lasers

Abstract Engine diagnostic procedures have contributed substantially to the advancement shown by the internal combustion engine over the years. The advent of the laser has led to a number of optical techniques offering new diagnostic capabilities. To provide a foundation from which to judge the attributes of these modern tools, in this paper prior engine research is reviewed in selected areas to illustrate the kinds of measurements that have proved useful, and instrumentation predating the laser that has made those measurements possible is surveyed. Finally, some research needs are enumerated that might be beneficially addressed with new diagnostic tools.

Dynamometer-Based Evaluation of Low Oxides of Nitrogen, Advanced Concept Diesel Engine for a Passenger Car

An Advanced Concept Diesel (ACD) engine, previously evaluated under a U.S. Energy Research and Development Administration contract, was dynamometer tested to provide data for the computer simulation of a diesel passenger car. The car was calculated to have the potential for meeting a 0.25 g/km (0.4 g/mi) NO standard (without cold start) if high EGR rates were introduced. The 0.25 g/km (0.41 g/mi) hydrocarbon standard would not be met by the unmodified vehicle, although use of an advanced transmission was projected to decrease hydrocarbons just to that level. Before the ACD engine is considered further, adequate durability should be demonstrated with high EGR rates, and lower hydrocarbon emissions are needed.

How Shall we Power Tomorrow’s Automobile?

The thrust toward further gains in the fuel-utilization efficiency of the passenger-car engine, without sacrificing its many other desirable attributes, is continuing. The search for an attractive alternative powerplant has always been included in such efforts, but so far none has emerged. Prominent on the list of contenders today are the Stirling engine, the gas turbine, and the advanced diesel, including uncooled versions incorporating structural ceramics. Large-scale production of none of these is projected for passenger cars in the foreseeable future. Meanwhile, improvements continue to be made to indicated thermal efficiency, mechanical efficiency, and volumetric efficiency of the spark-ignition engine. Supercharging and variable engine geometry are additional options, and the advent of electronic controls has proven beneficial. The spark-ignition engine promises the ability to operate on the leading alternative fuels. Given the evolving scenario, that engine is expected to remain dominant in passenger cars to the end of this century.

Comparison of Some Analytical and Experimental Correlations of Axial-Flow Turbine Efficiency

The first phase of the axial-flow turbine design problem involves selection of a velocity diagram. This choice exerts an important influence on turbine efficiency. Design charts relating turbine efficiency to the velocity diagram, through a work coefficient and a flow coefficient, are therefore useful in preliminary design. In this study such design charts are constructed using two established analytical methods. The results are compared with a published correlation based on experimental data. Simple constructional methods are indicated whereby these charts can be used to obtain preliminary estimates of rotor blade stress and relative temperature, two factors influencing blade life.Copyright