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.
It was found that a Diesel engine incorporated with an HIP under varied operational conditions, including those encountered in uncooled engine design needs variation of injection parameters, namely the start of injection and the rate shape. When the engine operating condition shifts, the rapid variation of those parameters are needed in order to optimize the engine power delivery and fuel consumption as well as to minimize smoke emissions.
Other engine responses to the varied parameters in this high-pressure Diesel engine are also reported in the paper.