Experimental study has been carried out using corn and soybean fuel blends at the most recommended
blending ratio of 20% biodiesel (C20 and S20) with conventional diesel fuel as alternative fuel for diesel
engines. The effect of fuel injection pressure (IP) on diesel engine performance using C20 and S20 blends
in comparison with that using neat diesel fuel is studied. Preliminary experiments regarding the analysis
of fuel properties indicate that a preheat temperature up to 60–80 C for these biodiesel fuel blends is
necessary to compensate their high viscosity as compared with that of neat diesel fuel. A series of tests
are conducted on four-stroke single cylinder air cooled direct injection (DI) diesel engine at different
engine speeds, loads and IP of 180, 190 and 200 bar. The investigating parameters include the engine performance
parameters (brake thermal efficiency – gB and brake specific fuel consumption – BSFC) and
other necessary parameters (air-to-fuel ratio – A/F ratio, mass of injected fuel – mf, exhaust gas temperature
– Texh, cylinder wall temperature – Twall, in-cylinder dynamic pressure – Pcyl, and both value and
position of maximum pressure – Pmax and h@Pmax, respectively). The properties of corn and soybean
blended fuels affect the fuel injection system and cause an increase in the duration of fuel injection to
cover more time according to the increase in the amount of injected fuel necessary to overcome the
power loss accompanied with the biodiesel low energy content. The major conclusion is that, the
increased injection pressure gives better results regarding the engine performance parameters (both
BSFC and gB) in comparison with case of the original injection pressure for all tested fuels, thus the best
results are obtained at high injection pressure of 200 bar. At this conditions it is concluded that, the
increase of engine gB and the decrease of BSFC approach 15% (from the original pressure of 180 bar),
while the values of Pmax for diesel fuel are slightly higher than those for blended fuels no matter the
engine operating conditions. |
