What is the different between HCCI, PCCI, RCCI and GDCI combustion?
in RCCI which type of LRF and HRF used?
HCCI, PCCI, RCCI, and GDCI are different combustion modes that have been developed to improve the efficiency and reduce the emissions of internal combustion engines.
HCCI (Homogeneous Charge Compression Ignition) is a mode of combustion where the air and fuel are mixed homogeneously and compressed until auto-ignition occurs. This mode is typically used in gasoline engines.
PCCI (Premixed Charge Compression Ignition) is a mode of combustion where the fuel is premixed with air and then compressed until auto-ignition occurs. This mode is typically used in diesel engines.
RCCI (Reactivity Controlled Compression Ignition) is a mode of combustion that combines features of both HCCI and PCCI. In RCCI, two different fuels are injected separately into the combustion chamber: one with high reactivity (such as gasoline) and one with low reactivity (such as diesel). The two fuels are mixed and then compressed until auto-ignition occurs. RCCI can be used in both gasoline and diesel engines.
GDCI (Gasoline Direct Injection Compression Ignition) is a mode of combustion that combines gasoline direct injection with compression ignition. In GDCI, gasoline is injected directly into the combustion chamber and then compressed until auto-ignition occurs. GDCI is typically used in gasoline engines.
A few points to add to the thorough description given by Ahmed above:
HCCI and PCCI are both suitable for CI engines. One main distinction of PCCI is that air and fuel are premixed, though not completely. In other words it uses a partially premixed (or stratified) charge, unlike HCCI, where the mixture is homogeneous. Stratified mixture is easier to achieve and may also help in controlling the onset of combustion to a certain extent.
There is also a combination of SI and CI modes, called SPCCI (Spark Controlled Compression Ignition). This is used in Mazda's Skyactiv-X engine.
Here a small quantity of air-fuel mixture is ignited by spark, but the resulting high pressure and temperature causes autoignition of the rest of the mixture, which is usually ultra-lean.
In RCCI, the LRF (e.g. gasoline or another low cetane fuel) may be injected in the intake manifold or port, while the HRC (usually diesel / biodiesel) is injected into the combustion chamber. Varying the LRF:HRF ratio is useful for controlling the start of combustion.
The type of LRF and HRF to be used in RCCI solely depends on what you would like to achieve. There is no defined type of fuel for RCCI.
In HCCI, the charge is completely premixed. To create concentration stratification, PCCI was suggested. A significant part is early injected preceding the compression stroke to make a premixed charge, then a portion of the fuel is introduced close to TDC. More details in these articles
Article Investigative research of diesel/ethanol advanced combustion...
Article A comparative study for the effect of different premixed cha...
Article Fuel Reactivity Controlled Compression Ignition Engine and P...
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