area of pe4 indicator diagram almost appears before the
maximum pressure value of normal combustion, and more
exists in the compression stage of the piston upwards before
the top dead center. Because the area of the cylinder wall
exposed to the igniting mixture of high temperature is larger
in pre-ignition case than in normal combustion case, the more
amount of heat is transmitted to the wall. On the other hand,
the piston do more negative work at the final stage of
compression stroke in pre-ignition case, thus the effective
work done at the combustion expansion stroke is less than
that of normal combustion. From formula (3), it can be known
that the hydrogen internal combustion engine increases the
heat transfer to the surface of combustion chamber, the top
surface of piston, the cylinder head, and the cylinder wall and
so on. The increasing amount of heat transmitted to the wall
further heats the incandescent spot and makes the exhaust
temperature higher. Accompanied with the over-hot
phenomenon, that makes the initial temperature of cylinder
at next circulation higher, and creates conditions for earlier
ignited the mixture.
If no measures are taken in time to suppress pre-ignition of
the hydrogen fueled engine, the mixture will be earlier ignited
by the hotter incandescent spot at the next circulation. The
crank angle corresponding to the maximum combustion
pressure, the highest temperature are advanced in comparison
with the value of last circulation, the heat transfer to the
machine wall also keep on increasing, and the temperature of
incandescent spot and the exhaust temperature continue to
increase as well. Whereas, because of the increase of the heat
transfer to the machine wall caused by pre-ignition, the
maximum combustion pressure and maximum rate of pressure
rise are relatively lower than that of last circulation at the
same of the excess air ratio.
On the other hand, the beginning time of pre-ignition
advances continuously at the compression initial stage
circulation by circulation, the heat transfer to the machine
wall also keep on increasing, and the temperature of the
incandescent spot at the compression initial stage become
higher and higher. At last the incandescent spot can very
easily ignite the fresh charge entered by the open of inlet
valve, and thus backfire is caused. It should also be pointed
that backfire easily happens in the rich mixture, and the
maximum combustion pressure and temperature, rate of
temperature and pressure rise increase with less of the excess
air ratio. And the backfire under high compression ratio and
high load makes the temperature in the cylinder higher, and
easily causes some incandescent spots, which can ignite the
mixture, and lead to pre-ignition.
area of pe4 indicator diagram almost appears before themaximum pressure value of normal combustion, and moreexists in the compression stage of the piston upwards beforethe top dead center. Because the area of the cylinder wallexposed to the igniting mixture of high temperature is largerin pre-ignition case than in normal combustion case, the moreamount of heat is transmitted to the wall. On the other hand,the piston do more negative work at the final stage ofcompression stroke in pre-ignition case, thus the effectivework done at the combustion expansion stroke is less thanthat of normal combustion. From formula (3), it can be knownthat the hydrogen internal combustion engine increases theheat transfer to the surface of combustion chamber, the topsurface of piston, the cylinder head, and the cylinder wall andso on. The increasing amount of heat transmitted to the wallfurther heats the incandescent spot and makes the exhausttemperature higher. Accompanied with the over-hotphenomenon, that makes the initial temperature of cylinderat next circulation higher, and creates conditions for earlierignited the mixture.If no measures are taken in time to suppress pre-ignition ofthe hydrogen fueled engine, the mixture will be earlier ignitedby the hotter incandescent spot at the next circulation. Thecrank angle corresponding to the maximum combustionpressure, the highest temperature are advanced in comparisonwith the value of last circulation, the heat transfer to themachine wall also keep on increasing, and the temperature ofincandescent spot and the exhaust temperature continue toincrease as well. Whereas, because of the increase of the heattransfer to the machine wall caused by pre-ignition, themaximum combustion pressure and maximum rate of pressurerise are relatively lower than that of last circulation at thesame of the excess air ratio.On the other hand, the beginning time of pre-ignitionadvances continuously at the compression initial stagecirculation by circulation, the heat transfer to the machinewall also keep on increasing, and the temperature of theincandescent spot at the compression initial stage becomehigher and higher. At last the incandescent spot can veryeasily ignite the fresh charge entered by the open of inletvalve, and thus backfire is caused. It should also be pointedthat backfire easily happens in the rich mixture, and themaximum combustion pressure and temperature, rate oftemperature and pressure rise increase with less of the excessair ratio. And the backfire under high compression ratio andhigh load makes the temperature in the cylinder higher, andeasily causes some incandescent spots, which can ignite themixture, and lead to pre-ignition.
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