Table 1 Principal particulars of test engine
Type: Vertical, 4-Cycle, Single acting diesel engine Super Charged, Water Cooled
Cylinder bore: 230 mm
Stroke: 380 mm
Number of cylinders : 3
Maximum continuous output: 257 kW(350 PS)
Maximum rotational speed: 420 rpm
Mean piston speed: 5.32m/s
Maximum combustion pressure: 9.32 MPa (95.0 kg/cm2)
Brake mean effective pressure: 1.55 MPa (15.8 kg/cm2)
Compression ratio: 13
2.1.2 Fuel used in test
MDF and MFO shown in Table 2 were used in the test.
2.1.3 Measuring instrument
The measured composition of the exhaust gas and the kinds of the measuring instruments are shown in Table 3. Soot content in exhaust gas was measured in accordance with the method of measuring dust content in flue gas (specified by JIS Z8808). Therefore, the soot measured by this equipment is not the same as the particulate measured by the method specified by ISO 8178.
2.1.4 Test method
The diesel engine was run at 25% load, 50% load, 75% load and 100% load of maximum continuous output with a propeller law using 12 kinds of fuel, the characteristics of the diesel engine and the concentration of NOx, O2, CO2, CO, HC and soot in the exhaust gas from the engine were measured, and the effect of the fuel property on the harmful exhaust emissions was examined. The intake air temperatures at the outlet of an intercooler were controlled at constant temperatures such as 43℃ at 75% load and 48℃ at 100% load, but they could not be controlled at low load to be 11〜27℃ at 25% load and 23〜35℃ at 50% load. The temperature of the fuel was set to be approximately 100℃ at the inlet of the fuel pump in a case of MFO.
