Page 434 - Advances in Eco-Fuels for a Sustainable Environment

Engine modification for alternative fuels usage in diesel engine 387

in the blends, which improves the combustion efficiency and results in lower CO and UBHC
emission formation. Furthermore, advancing the FIT from 19 to 27°CA bTDC results in the
decrement of the CO and UBHC emission for B85-D5-P10.
B85-D5-P10 blend has the maximum NO emission of 1946ppm at NOP of 600bar and FIT
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of 27°CA bTDC, which was 8% less than diesel and 47% higher than B100 at NOP of 600bar
and FIT of 27°CA bTDC. B85-D5-P10 blend has the minimum smoke emission of 1.52 FSN
obtained at NOP of 500bar and FIT of 27°CA bTDC, which was 57% less than diesel and
51% less than biodiesel. When the FIT is advanced from 19 to 27°CA bTDC, and when the
NOP is increased from 200 to 600bar, the NO emission increases and smoke emission
decreases for the B85-D5-P10 blend as related to other tested blends. This is due to the com-
bined effect of oxygen availability in the blend and the increment in NOP that improved the
atomization rate, resulting in complete combustion of hydrocarbon fuel. This complete com-
bustion causes more NO emission and lower smoke emission formation at advanced FIT and
higher NOP.
l B90-D5-H5 blend has the maximum CGPP of 64.68bar at NOP of 500bar and FIT of 27°CA
bTDC, which was 1bar less than diesel fuel at the same FIT and NOP. The minimum CGPP
of 60.56bar was obtained in B100 at NOP of 200bar and FIT of 19°CA bTDC. B90-D5-H5
blend has the maximum CGPP as related to other tested fuels due to the combined effect of
oxygen availability and higher heating value. Premixed combustion is contributed for higher
CGPP. Advanced FIT timing prolonged the ignition delay period, causing more fuel to be
burned in the premixed combustion zone attributed to higher CGPP. The CGPP increased
with increase in NOP and FIT for all tested fuels.
l B85-D5-H10 and B85-D5-P10 blends have the maximum ignition delay period of 18°CA
and 17.5°CA at NOP of 200bar and FIT of 27°CA bTDC, which was 1°CA less than diesel.
Minimum ignition delay was obtained at higher NOP and lower FIT. At NOP of 500bar and
FIT of 19°CA bTDC, B100 and B85-D5-H10 blends have the minimum ignition delay
period of 11°CA bTDC and 11°CA bTDC, respectively. B85-D5-H10 blend has a lower
cetane number and a higher latent heat of evaporation, which prolonged the ignition delay
period of the blend. When the NOP was increased, the ignition delay period reduced for all
tested fuels due to the improvement in atomization and vaporization processes.
l B90-D5-H5 blend has the maximum HRR of 44.85J/°CA, which was 5% less than diesel,
14.2% higher than the B85-D5-P10 blend, and 20% higher than the B100 at NOP of 500bar
and FIT of 27°CA bTDC. Premixed combustion is the main contributor for higher HRR.
Among all the tested fuels, B90-D5-H5 blend has the maximum HRR due to its higher
heating value and lower viscosity. In addition, advanced FIT provides a longer delay period,
which results in more fuel burned in the premixed combustion zone, thus releasing more heat
during the period.
Biodiesel-diesel-pentanol and biodiesel-diesel-hexanol blends produced lower exhaust
emissions when compared to conventional diesel fuel irrespective of NOP and FIT.
Hence, biodiesel-diesel-n-pentanol and biodiesel-diesel-n-hexanol blends could be a
promising alternative fuel for the internal combustion engine. (1) Higher NOP and
advanced FIT are recommended for higher viscosity fuel to achieve better engine per-
formance and lower engine emission characteristics. (2) More research could be done to
find ecofriendly additives that can be added to biodiesels to improve their chemical and
physical properties. (3) Further, improvement in the engine performance and reduction
in the engine emissions can be achieved through employing split and multiinjection
strategies on CRDI-assisted diesel engines fueled with biodiesel-diesel-alcohol blends.