The test results show that the final combustion of oxygenated blends ERO at late phases of the expansion stroke may lead to the lower emission of NO, CO, HC and smoke but does not contribute to having better brake mean effective pressure, higher thermal efficiency and biofuel savings at a high speed of 2200 [min.sup.-1].
The brake mean effective pressure of the engine running under heavy loads, [lambda] = 1.6, depends actually on the speed and biofuel used.
Fig.6 shows the variation of hydrocarbon emission with brake mean effective pressure under various compression ratios.
The NO emissions of the engine using different fuel blends and neat diesel with respect to brake mean effective pressure for the compression ratios 15, 17 and 19 are shown in Fig.7.
The black smoke emission resulting from combustion of diesel-ethanol-biodiesel blends and neat diesel are plotted against the brake mean effective pressure in the Fig.8.
The lowest specific energy consumption is observed as 13860kJ/kW-hr for neat diesel under the compression ratio of 17 and the highest specific energy consumption is observed as 15924.98kJ/kW-hr for E25 blend at the compression ratio of 19 under the economic loading condition at the brake mean effective pressure of 0.44MPa.
A load step from 4 to 6 bar brake mean effective pressure at an engine speed of 2000 [min.sup.-1] is shown as an example.
Due to the adjustable vane oil pump, which increases the oil pressure at a brake mean effective pressure of between 6 and 8 bar and also simultaneously activate the piston cooling, an increase in oil pump friction can be recognized in this switching range.
The analyzed point of load was 1750 [min.sup.-1] at a brake mean effective pressure of 3 bar.