Partially premixed combustion

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Partially premixed combustion (PPC), also known as PPCI (partially-premixed compression ignition) or GDCI (gasoline direct-injection compression-ignition) [1] [2] [3] [4] 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. As a compression-ignition engine, the fuel mixture ignites due to the increase in temperature that occurs with compression rather than a spark from a spark plug. [5] A PPC engine injects and premixes a charge during the compression stroke. This 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. [6] Challenges with using gasoline in a PPC engine arise due to the low lubricity of gasoline and the low cetane value of gasoline. Use of fuel additives or gasoline-diesel or gasoline-biodiesel blends can mitigate the various problems with gasoline. [7]

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References

Notes

  1. ↑ 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."
  2. ↑ Sellnau et al, 2014.
  3. ↑ Sellnau et al, 2015.
  4. ↑ 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"
  5. ↑ Putrasari, Yanuandri; Lim, Ocktaeck (2019). "A Review of Gasoline Compression Ignition: A Promising Technology Potentially Fueled with Mixtures of Gasoline and Biodiesel to Meet Future Engine Efficiency and Emission Targets". Energies. 12 (2): 238. doi: 10.3390/en12020238 .
  6. ↑ 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
  7. ↑ Putrasari, Yanuandri; Lim, Ocktaeck (2019). "A Review of Gasoline Compression Ignition: A Promising Technology Potentially Fueled with Mixtures of Gasoline and Biodiesel to Meet Future Engine Efficiency and Emission Targets". Energies. 12 (2): 238. doi: 10.3390/en12020238 . the lubricity of market gasoline is not adequate to protect today’s fuel injection components, so either the engine components must become more robust or fuel lubricity additives will be needed. Furthermore, the major challenge for GCI is the very small cetane value of gasoline that is usually estimated to be no higher than about 15. This low value leads to long ignition delays and misfires.
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