ic engines notes on non conventional engines
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Transcript of ic engines notes on non conventional engines
HCCI Engine
What Is HCCI?
HCCI is a combustion process. HCCI is not an
engine concept. HCCI must be incorporated in
an engine concept.
HCCI is a low temperature chemically controlled
(flameless) combustion process.
HCCI can be considered as a hybrid form
between the diesel and Otto combustion
process.
However combustion process is different. So
there is neither Diffusion flame (as in a diesel
engine) nor a flame front traveling through a
premixed charge ( as in SI engine).
WORKING PRINCIPLE OF HCCI
Homogenous charge is drawn in to the cylinder during suction and
compress to high enough temperature to achieve spontaneous ignition
of the charge.
Combustion starts in almost whole volume of C.C Two degree before
TDC
After Combustion initiation the temperature rapidly increases and
whole fuel burn simultaneously As whole mixture burns simultaneously
and no flame propagation , combustion temperature can be controlled
less than 700 deg Centigrade and thus NOx formation is avoided.
LEAN BURN ENGINE
Combustion is considered “lean”when excess air is
introduced into the engine along with the fuel
Advantages Of Burning Leaner Overall Fuel-Air Mixtures
1. Higher thermodynamic efficiency.2. Reduced airpollution
A relatively rich mixture was formed at the spark plug by an auxiliary spray while
another spray injecting fuel along the major axis of the combustion chamber
formed a leaner mixture