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Combustion studies on various potential alternative fuels were performed for the U.S. Array Belvoir Research and Development Center in a two-stroke heavy duty diesel engine. One cylinder of the engine was instrumented with a pressure transducer. A high-speed data acquisition system was used to acquire cylinder pressure histories synchronously with crankangle. The heat release diagrams, along with the calculated combustion efficiencies of the fuels were compared to a referee grade diesel fuel. The calculated and measured combustion parameters include heat release centroids, cumulative heat release, peak pressure, indicated horsepower, peak rate of pressure rise, indicated thermal efficiency, energy input, and ignition delay. Regression analyses were performed between various fuel properties and the calculated and measured combustion performance parameters. The fuel properties included specific gravity, cetane number, viscosity, boiling point distribution.

The technique of using cylinder pressure data for diagnosing the combustion process in a reciprocating internal combustion engine has been used for some time. Much of the early work, however, was qualitative comparisons of the heat release rate diagrams. Only recently have efforts been made to reduce the heat release diagrams to functional or numerical representations which could be used to make fuel-to-fuel and engine-to-engine comparisons. This paper describes work in which cylinder pressure measurements were taken from an operating diesel engine using a high-speed data acquisition system. Combustion chamber pressure measurements were made at approximately 1.0- degree increments over several engine cycles using a real-time data acquisition system. The pressure data were used to calculate apparent heat release and indicated horsepower. Both radiative and convective heat transfer computations were included in the calculational procedures.