combustion takes place at low temprature so this should reduce thermal efficiency.
misfiring can occur how is it eliminated
The two primary reasons for improved efficiency are (a) ability to operate at higher, diesel-like compression ratios, and (b) lower throttling losses. In addition, engines with this technology typically also deploy variable valve timing, which improves cycle efficiency by effectively having a longer expansion stroke than compression stroke. Other primary advantages (though not efficiency related) are lower NOx and soot emissions and fuel flexibility.
The disadvantages include more difficult engine control, difficult startup operation, commonly very high pressure and heat release rates associated with the rapid reactions, higher CO and HC emissions than typical spark-ignited engines, and restricted power range.
The two primary reasons for improved efficiency are (a) ability to operate at higher, diesel-like compression ratios, and (b) lower throttling losses. In addition, engines with this technology typically also deploy variable valve timing, which improves cycle efficiency by effectively having a longer expansion stroke than compression stroke. Other primary advantages (though not efficiency related) are lower NOx and soot emissions and fuel flexibility.
The disadvantages include more difficult engine control, difficult startup operation, commonly very high pressure and heat release rates associated with the rapid reactions, higher CO and HC emissions than typical spark-ignited engines, and restricted power range.
I agree with Larry Baxter. Regarding the combustion temperature, the efficiency of an IC engine is not necessarily given by the peak combustion temperature. The HCCI regime is practical only at low loads, where a "traditional" engine is throttled, but with HCCI, you can run with considerably more excess air, reducing the throttling losses. Primarily for this reason you get higher efficiency compared to the traditional engine. High expansion ratio can also be used with traditional engines (i.e. Toyota Prius since late 90's).
Sufficiently good combustion takes place at low temperature itself is plus point so that it may reduce heat loss to cyl walls,reducing cooling requirement which may increase or has good thermal efficiency.Also HCCI uses almost all OXYGEN compared to conventional engines with smooth operation less NOx etc results in better performance.If we go for HCCI then its like S.I engine, for which engine size should be reduced to have more benefits, higher mean effective pressure & injector with 3,4 holes.
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