Two important parameters in gasoline engines (premixedcombustion) are There is only one way to reduce the CO2 and that is byreducing the fuel consumption.įrom the carbon dioxide point of view, the Diesel engine istherefore more attractive than the Otto engine since it is Swirling engines have problems at high rpms. The most important part of theDiesel engine is the fuel injector.Recent development has leadto increasing fuel injection pres-sure and reduction in the orificediameter.Įach system requires a different, suitable, injectionsystem/strategy Otto engines have higher pump-losses at low loads, which leads to higher sfc. Specific Fuel Consumption as function of loadfor Diesel and Otto. Lower heat losses, higher efficiency more flexibility about choice of fuel
No pumping losses, power fuel combustion is always lean Higher thermodynamic efficiency, no knock no throttle Throttling is thus necessary at low loads, which takespower from the engine.ĭue to the fuel/air mixture it is necessary to lower thecompression ratio to avoid it from self-igniting (knock). Since the mixture always must be stoichiometric it isnecessary to reduce the amount of air that is drawninto the cylinder if we reduce the fuel amount. In the Diesel air enters the cylinder, fuel is injected,self-ignites and burns with a diffusion type ofcombustionĭiesel vs. In a Gasoline engine the air/fuel mixture enters thecylinder and creates a stoichiometric homogeneousmixture, which is ignited and the flame travels from thespark and outwards to the liner. The main difference between the Diesel and Otto engine is: Typical evolution of the heat release for Diesel combustion ExhaustThe hot gas is released to the surroundingĬlear lift-off and sooty flame (A. Power StrokeAround TDC fuel is injected, which self-ignitesand burns, further increasing pressure andtherby forcing the piston down.Ĥ. CompressionThe air is compressed tohigh temperature and pressureģ. (The Diesel Dilemma) New strategies and technolgiesĢ. Lecture Outline Diesel Engine Working Principle Difference between Gasoline and Diesel engine Diffusion Combustion Sprays Emissions Introduction to Combustion inDiesel Engines
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