Factors Affecting Diesel-Engine Efficiency and Combustion

CERTAIN theoretical phases of the subject are discussed by Mr. Hershey, who was associated with the investigation of internal-combustion-engine cycles which has been conducted for the last several years at the University of Illinois. In explanation of the objective of this discussion of Diesel-engine characteristics, he assumes that the primary interest of automotive engineers in the Diesel engine lies in its possible utilization as an automotive powerplant. He states that the use of this type of internal-combustion engine in general automotive service is still a somewhat remote possibility, but argues that, by a systematic study of both the Diesel and the Otto cycles, it is possible to obtain a much better understanding of the factors responsible for the particular characteristics of each. Once this point of advantage has been gained, it may be possible to combine the more desirable characteristics of each cycle and, by so doing, to develop new or slightly modified cycles which will meet present automotive requirements more satisfactorily than does either of the original cycles.

Associated with engines operating on the Diesel cycle are two characteristics which are generally regarded as being distinctive in the field of the internal-combustion engine. These are high thermal-efficiency and the ability to operate on relatively cheap, low-grade liquid fuels. It is these two factors of Diesel-engine performance which Mr. Hershey considers.