Partially premixed combustion
Partially premixed combustion (PPC), also known as PPCI (partially-premixed compression ignition) or GDCI (gasoline direct-injection compression-ignition)  is a modern combustion process intended to be used in internal combustion engines of automobiles and other motorized vehicles in the future. Its high specific power, high fuel efficiency and low exhaust pollution have made it a promising technology. A PPC engine injects and premixes a charge during compression stroke. Thus premixed charge is too lean to ignite during the compression stroke, the charge will ignite after the last fuel injection ends near TDC. The fuel efficiency and working principle of a PPC engine resemble those of Diesel engine, but the PPC engine can be run with a variety of fuels. Also the partially premixed charge burns clean.
- "Promising Delphi 1st-gen Gasoline Direct Injection Compression Ignition engine meeting ultra fuel efficient program targets". Green Car Congress. BioAge Group. 2014-04-17. Retrieved 2016-02-15.
- Johansson, Bengt (2010-04-29). "Partially Premixed Combustion, PPC, for high fuel efficiency engine operation" (PDF). Lund University. Archived from the original (PDF) on 2016-12-22. Retrieved 2016-02-15.
- Johansson, Bengt (2013-06-10). "Partially Premixed Combustion, PPC – Why all diesel engines should be run on gasoline" (PDF). Lund University. Archived from the original (PDF) on 2017-08-30. Retrieved 2016-02-15.
- Lindberg, Austin (2013-11-18). "Hyundai Developing Gasoline-Burning Compression-Ignition Engine". Car and Driver. Hearst Communications. Retrieved 2016-02-15.
- Sellnau, Mark; Foster, Matthew; Hoyer, Kevin; Moore, Wayne; Sinnamon, James; Husted, Harry (2014-04-01). "Development of a Gasoline Direct Injection Compression Ignition (GDCI) Engine" (PDF). SAE International Journal of Engines. SAE International. 7 (2). doi:10.4271/2014-01-1300. Retrieved 2016-02-15.[dead link]
- Sellnau, Mark; Moore, Wayne; Sinnamon, James; Hoyer, Kevin; Foster, Matthew; Husted, Harry (2015-04-14). "GDCI Multi-Cylinder Engine for High Fuel Efficiency and Low Emissions" (PDF). SAE International Journal of Engines. SAE International. 8 (2). doi:10.4271/2015-01-0834. Archived from the original (PDF) on 2017-05-17. Retrieved 2016-02-14.
- Tunér, Martin (2014-02-28). "State of the art of Partially Premixed Combustion (PPC)" (PDF). Lund University. Archived from the original (PDF) on 2016-02-16. Retrieved 2016-02-14.
- Tunér, Martin (2015-10-22). "Partially Premixed Combustion, PPC, for high efficiency and low emissions" (PDF). Lund University. Archived from the original (PDF) on 2016-01-28. Retrieved 2016-02-14.
- Green Car Congress, 2014. Quote: "Delphi has been developing a multi-cylinder engine concept for PPCI combustion with the current US market gasoline (RON91).… A multiple-late-injection (MLI) strategy with GDI-like injection pressures was selected without use of a premixed charge. The absence of classic knock and pre-ignition limits in this process enabled a higher compression ratio of 15. The engine operates “full time” over the entire operating map with partially premixed compression ignition. No combustion mode switching, diffusion controlled combustion, or spark plugs were used. Delphi uses the term Gasoline Direct Injection Compression Ignition (GDCI) in reference to this combustion process."
- Sellnau et al, 2014.
- Sellnau et al, 2015.
- Tunér, 2014. p. 5. Quote: "A loved child has many names
- Gautam Kalghatgi - Saudi Aramco – PPCI, GCI
- Lund – PPC
- Delphi – GDCI
- Eindhoven - PPC
- Wisconsin Madison – PPCI, GCI
- Sandia – PPCI, LTGC"
- Johansson, Bengt (2016). "Fuels and Combustion" (PDF). wiley-vch.de. Wiley-VCH. Retrieved 2016-08-29.
The concept is based on injection rather late in the compression stroke and operation with a significant ignition delay. A crude definition of PPC is that all the fuel should be in the cylinder at the time of ignition. This means that start of combustion (SOC) should be after end of injection (EOI). Most often, multiple injections are used with PPC to generate a suitable stratification of fuel/air in the cylinder at the time of ignition