Page 301 - Biosystems Engineering

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which results in an increase in the exhaust gas temperature. Again,
the exhaust gas temperature decreases with an increase in the ethanol
fumigation rate at constant engine speed. The latent heat of vaporiza-
tion of ethanol cools the intake charge sufficiently to reduce the peak
combustion temperature, which reduces the exhaust gas temperature.
It is observed that at an engine speed of 800 rpm and at no load, the
exhaust gas temperature is reduced by 3.37, 4.50, and 12.35 percent
at ethanol fumigation rates of 1.06, 1.45, and 2.06 kg/h (45, 54.57, and
62.17 percent diesel substitution), respectively, when compared to the
exhaust gas temperature under diesel fuel operation. At a high load
of 6.31 kW, the exhaust gas temperature is reduced by 11.09, 14.01,
and 16.67 percent at ethanol fumigation rates of 1.06, 1.45, and 2.06
kg/h, respectively, when compared to the exhaust gas temperature
under diesel fuel operation. It is observed that at ethanol fumigation
rate of 1.06 kg/h engine performs satisfactorily over a range of speeds
such as 800, 900, 1000, and 1100 rpm. Hence, the fumigation rate of
1.06 kg/h (45 percent diesel substitution) is selected as the optimum.
Because ethanol is not a compression ignition engine fuel, ethanol
is fumigated into the airstream in the intake manifold to improve the
ignition quality of the fuel. The brake thermal efficiency, BSFC, NO
x
emission level, exhaust gas temperature, and smoke level decreases
with ethanol fumigation at constant engine speed. Diesel substitution,
energy replacement, and CO emission level increase with an increase
in the ethanol fumigation rate at constant engine speed. The fumiga-
tion rate of 1.06 kg/h (45 percent diesel substitution) is found to be
optimum for good engine performance. Ethanol fumigation in diesels
has the advantages for the NO and smoke level reduction, which
x
affect good environmental impact. The increase in CO emission level
with ethanol fumigation is in a safe range.

References
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