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Alternative Fuels for Transportation
However, at high loads there is a tendency for preignition and an increase in
NO x emissions also.
Preignition is defined as combustion prior to spark discharge that results
from surface ignition at engine hot spots, such as spark electrodes, valves,
or engine deposits. The limiting effect of preignition is that a preignition
event will advance the start of combustion and produce an increased chemical heat release rate and rapid rate of pressure rise, high peak pressures that
lead to higher in-cylinder surface temperatures.
In hydrogen engines, premature ignition is a problem because of its lower
ignition energy, wider flammability range, and shorter quenching distance.
Premature ignition occurs when the fuel mixture in the combustion chamber ignited before ignition by the spark plug and results in an inefficient
rough running engine. If the premature ignition occurs near the fuel intake
valve the resultant flame travels back into the induction system thus causing
backfire. Crankcase oil enters into the combustion chamber through blow-by
and in suspended form, or in the crevices just above the top piston ring, and
acts as a hot spot that may contribute to preignition (White, Steeper, and Lutz
2006). Preignition in hydrogen vehicles, can be avoided by
• Injecting cold exhaust gases into the cylinder
• Injecting cold gaseous hydrogen
• Injecting water into the cylinder
• Increasing the compression ratio
• Using lean burn carburetor
9.11 Hydrogen in Compression Ignition Engines
Hydrogen can be used in CI engines in two ways: dual fuel mode and surface ignition.
9.11.1 Dual Fuel Mode Operation
In this method, hydrogen is inducted into the combustion chamber along
with fresh air and compressed and then ignited by a spray of injected liquid
fuel (diesel). Lkegami, Miwa, and Shioji (1982) investigated hydrogen combustion in a conventional swirl chamber type diesel engine. It has been reported by the investigators that hydrogen-fueled diesel combustion could be
achieved to a limited extent because of the autoignition characteristics of the
fuel. The problems associated with this method are: when an insufficient
quantity of fuel is injected then incomplete combustion will occur and when
hydrogen-gas mixture becomes rich combustion becomes uncontrollable.
Alternative Fuels for Transportation
However, at high loads there is a tendency for preignition and an increase in
NO x emissions also.
Preignition is defined as combustion prior to spark discharge that results
from surface ignition at engine hot spots, such as spark electrodes, valves,
or engine deposits. The limiting effect of preignition is that a preignition
event will advance the start of combustion and produce an increased chemical heat release rate and rapid rate of pressure rise, high peak pressures that
lead to higher in-cylinder surface temperatures.
In hydrogen engines, premature ignition is a problem because of its lower
ignition energy, wider flammability range, and shorter quenching distance.
Premature ignition occurs when the fuel mixture in the combustion chamber ignited before ignition by the spark plug and results in an inefficient
rough running engine. If the premature ignition occurs near the fuel intake
valve the resultant flame travels back into the induction system thus causing
backfire. Crankcase oil enters into the combustion chamber through blow-by
and in suspended form, or in the crevices just above the top piston ring, and
acts as a hot spot that may contribute to preignition (White, Steeper, and Lutz
2006). Preignition in hydrogen vehicles, can be avoided by
• Injecting cold exhaust gases into the cylinder
• Injecting cold gaseous hydrogen
• Injecting water into the cylinder
• Increasing the compression ratio
• Using lean burn carburetor
9.11 Hydrogen in Compression Ignition Engines
Hydrogen can be used in CI engines in two ways: dual fuel mode and surface ignition.
9.11.1 Dual Fuel Mode Operation
In this method, hydrogen is inducted into the combustion chamber along
with fresh air and compressed and then ignited by a spray of injected liquid
fuel (diesel). Lkegami, Miwa, and Shioji (1982) investigated hydrogen combustion in a conventional swirl chamber type diesel engine. It has been reported by the investigators that hydrogen-fueled diesel combustion could be
achieved to a limited extent because of the autoignition characteristics of the
fuel. The problems associated with this method are: when an insufficient
quantity of fuel is injected then incomplete combustion will occur and when
hydrogen-gas mixture becomes rich combustion becomes uncontrollable.