Diesel Stoichiometric Combustion

1
Diesel Stoichiometric Combustion
SANGSUK LEE Rolf D. REITZ
Motivation
Operating Conditions
Effects of Op. Parameters on Fuel Consumption
under stoichiometric Operation

• Diesel engines face difficulties in satisfying
  emission regulations, especially reducing NOx
  emissions.
• Three-way catalyst is an well-established
  technology with gasoline engines.
• Can the three-way catalyst be used with diesel
  engines?
• Fuel Economy is top priority!
• Emissions

Linear Regression (R2 80)
Injector Nozzles
ISFC (g/kW-hr) 307 0.38xBoost P. 0.21x
Inj. P.
5.82xSwirl 0.11xSOI
0.11xFuel
Mass 0.06xIntake Temp.

• 130 (8-hole)
• 400 cm3 / 30 min
• under 100bar

Boost Pressure Injection Pressure
gt Swirl gt Fuel Mass SOI Intake Temp. ?
Objectives

• To explore characteristics of rich diesel
  combustion
• To achieve Diesel Stoichiometric Combustion with
  acceptable fuel economy impact
• To identify achievable level of fuel consumption
  under stoichiometric operation with current
  strategies
• To evaluate the effects of operating parameters
  on diesel stoichiometric characteristics

• Combustion regimes dont have significant effect
  on fuel consumption as ? becomes richer.
• 7 fuel consumption disadvantage at ? 1.0

Minitab
Combustion Phasing on Fuel Consumption
Split Injection under phi 1.0
Emissions under phi 1.0
Conclusions
ISFC

• Fuel consumption and emissions characteristics
  are determined mostly by the equivalence ratio
  under rich diesel combustion.
• PCCI combustion showed a low level (0.2 g/kW-hr)
  of soot emission even at stoichiometric
  operation.
• Stoichiometric operation yielded ISFC levels of
  about 245 g/kW-hr which is around 7 higher than
  that of the best fuel economy case under leaner
  standard diesel operation.
• High boost pressure and injection pressure
  improved fuel consumption under stoichiometric
  operation while high swirl ratio sacrificed fuel
  consumption.
• Phasing of the heat release rate had only a minor
  influence on the fuel consumption since better
  phasing was accompanied by longer burn durations
  which canceled the gain.
• PCCI based split injections under stoichiometric
  operation did not have significant fuel economy
  advantage while split injections with late
  injection impacted fuel economy due to improper
  air entrainment of 2nd spray.

SOI -35 15 ATDC
SOI -35 -15 ATDC

• Same Levels of ISFC and Heat rejection efficiency
• Shifted combustion phasing doesnt improve work
  conversion efficiency and fuel consumption.

Fuel Energy Wasted with CO
and HC Emissions
Red Significant Effect gt 2 ? Blue
Moderate Effect gt ? Black negligible
Effect lt ?
4.7