Ethanol
149
In a study by Goering et al. (1987), 200-proof fumigated ethanol supplied
35% of the total energy to a six-cylinder, turbocharged (TC), DI, CI engine
running at full load and 90% under light loads. The latter investigators found
that engine knock limited the maximum fumigation rate at full load, while
engine misfire limited the maximum rate at light load. Barnes, Kittelson, and
Murphy (1975) were able to supply 40% of the total energy to a multicylinder, TC engine at full load. Note that, if the rate of ethanol fumigation is not
varied with engine load, the engine governor will cause the percentage of
energy supplied by fumigated ethanol to be highest under light load and
to decrease progressively as engine load is increased in the governor-controlled range. Provision must be made for limiting or stopping the flow of
fumigated ethanol when all loads are removed from the engine. The engine
will accelerate to the point of destruction otherwise.
When fumigated ethanol is used to replace a portion of the primary fuel
rather than being used to over fuel the engine, most investigators have found
a substantial reduction in exhaust smoke, little change in carbon monoxide
emissions but a large increase in unburned hydrocarbons, especially at
lighter loads. Goering et al. (1987) found that fumigation greatly reduced NO x
emissions at light loads but slightly increased them at moderate to full loads.
Most investigators found that brake thermal efficiency was slightly reduced
by fumigation under light loads but slightly increased under a full load.
5.5.2 glow Plug Assisted ignition
Kroeger (1986) modified a Caterpillar CI engine to run on methanol by
installing a glow plug in each cylinder to ignite the fuel. An injection system
of greater capacity was installed in the modified engine to offset the lesser
heating value of the methanol.
Goering, Parcell, and Ritter (1998) experimented with a Detroit Diesel DI,
CI, V6, 2-cycle bus engine that had been modified by Detroit Diesel to run on
ethanol fuel. The Roots blower in the engine was bypassed at higher loads
and a turbocharger was used to boost air consumption. Glow plugs were
used to assist autoignition of the ethanol at start-up, during warm-up and
for low-speed, light-load operations. Exhaust scavenging control was used to
increase the residual fraction of exhaust gases in the combustion chambers
to aid autoignition. The engine was equipped with a catalytic converter for
exhaust gas treatment. The engine was calibrated to provide 207 kW of brake
power while running on 200-proof ethanol denatured with 5% gasoline as the
baseline fuel. Lubrizol 9520A fuel additive was added to the baseline fuel in
0.06% concentration. In the experiments by Goering, Parcell, and Ritter (1998)
the engine was run on the baseline fuel and on the baseline fuel with enough
distilled water added to simulate 190-proof ethanol. The engine was run for
454 hours on a load–speed cycle designed to simulate operation of Chicago
Transit Authority buses. Test results are summarized in Figure 5.14. Except
for an incident of injector needle sticking that caused power to decline, the
149
In a study by Goering et al. (1987), 200-proof fumigated ethanol supplied
35% of the total energy to a six-cylinder, turbocharged (TC), DI, CI engine
running at full load and 90% under light loads. The latter investigators found
that engine knock limited the maximum fumigation rate at full load, while
engine misfire limited the maximum rate at light load. Barnes, Kittelson, and
Murphy (1975) were able to supply 40% of the total energy to a multicylinder, TC engine at full load. Note that, if the rate of ethanol fumigation is not
varied with engine load, the engine governor will cause the percentage of
energy supplied by fumigated ethanol to be highest under light load and
to decrease progressively as engine load is increased in the governor-controlled range. Provision must be made for limiting or stopping the flow of
fumigated ethanol when all loads are removed from the engine. The engine
will accelerate to the point of destruction otherwise.
When fumigated ethanol is used to replace a portion of the primary fuel
rather than being used to over fuel the engine, most investigators have found
a substantial reduction in exhaust smoke, little change in carbon monoxide
emissions but a large increase in unburned hydrocarbons, especially at
lighter loads. Goering et al. (1987) found that fumigation greatly reduced NO x
emissions at light loads but slightly increased them at moderate to full loads.
Most investigators found that brake thermal efficiency was slightly reduced
by fumigation under light loads but slightly increased under a full load.
5.5.2 glow Plug Assisted ignition
Kroeger (1986) modified a Caterpillar CI engine to run on methanol by
installing a glow plug in each cylinder to ignite the fuel. An injection system
of greater capacity was installed in the modified engine to offset the lesser
heating value of the methanol.
Goering, Parcell, and Ritter (1998) experimented with a Detroit Diesel DI,
CI, V6, 2-cycle bus engine that had been modified by Detroit Diesel to run on
ethanol fuel. The Roots blower in the engine was bypassed at higher loads
and a turbocharger was used to boost air consumption. Glow plugs were
used to assist autoignition of the ethanol at start-up, during warm-up and
for low-speed, light-load operations. Exhaust scavenging control was used to
increase the residual fraction of exhaust gases in the combustion chambers
to aid autoignition. The engine was equipped with a catalytic converter for
exhaust gas treatment. The engine was calibrated to provide 207 kW of brake
power while running on 200-proof ethanol denatured with 5% gasoline as the
baseline fuel. Lubrizol 9520A fuel additive was added to the baseline fuel in
0.06% concentration. In the experiments by Goering, Parcell, and Ritter (1998)
the engine was run on the baseline fuel and on the baseline fuel with enough
distilled water added to simulate 190-proof ethanol. The engine was run for
454 hours on a load–speed cycle designed to simulate operation of Chicago
Transit Authority buses. Test results are summarized in Figure 5.14. Except
for an incident of injector needle sticking that caused power to decline, the