Relationships Between Exhaust Smoke Emissions and Operating Variables in Diesel Engines

Diesel Particulates—What They Are and Why

“…Because of the small fraction of the total fuel injected during the brief second stage, the fuel involved in diffusive burning is approximated by the quantity injected after the ignition delay period. Although appropriate data are not available from an ID1 passenger-car engine, such data are available for an engine in which injection timing was varied at constant overall equivalence ratio by Bryzik and Smith (1977). Results are plotted for an air,'fuel ratio of 18 in Figure 19 as percent opacity of the exhaust, which is an indicator of soot content, against the fuel fraction injected after ignition delay.…”

System identification of the smoke opacity vs fuel metering in a diesel engine

“…The level of particulate emission produced by a diesel engine depends on the engine design, the operation mode, the properties of the fuel used and the ambient conditions. The effects of these variables on particulate emission have been studied by many researchers (Henein, 1979, Hames et al, 1971, Khan et al, 1972, Bryzik and Smith, 1978, Van Gerpen, 1984. Those variables include fuel type, injection system (rate, timing, and nozzle configuration), inlet air temperature, air swirl level, air-fuel ratio, and engine speed.…”

“…temperature. The effect of time available is, however, obvious; at higher engine speeds, the carbon formed during the combustion process has less time to mix and react with oxygen resulting in higher smoke levels (Bryzik and Smith, 1978).…”

“…Based on the time-invariance effect of a linear model, frequency domain analysis was applied. The smoke production in diesel combustion is caused by many design and operating parameters, such as air/fuel ratio, injection system and engine speed (Bryzik and Smith, 1978). The level of black smoke is not significant in steady state operation with properly operated diesel engines (Henein, 1979) and the fast change in fuel metering rate caused by poor control of fuel injection pump increases the smoke exhaust level.…”