Why? The stationary diesel engines are among the most efficient power producing devices (about 50%). Why? Despite higher power to weight ratios, two-stroke engines are not used in automobiles. QUESTIONS? Diesel engines operate at higher air-fuel ratios than gasoline engines. 33ДЈ4 Dual cycle: A more realistic ideal cycle model for modern, high-speed compression ignition engine. Less economical (fuel short circuiting) More pollution Simpler & lighter constructionДў0 Petrol vs Diesel Petrol as fuel Otto Cycle Spark Ignition (SI) (spark plug) Compression ratio ~7:1 to ~11:1 Fuel-Air Mixture induced (carburetor) Less economical fuel consumption Diesel as fuel Diesel Cycle Compression Ignition (CI) (no spark plug) Compression ratio ~12:1 to ~24:1 Only air is induced (fuel injection) More economical fuel consumptionДў1 Petrol vs Diesel (cont.) Less pollution Lighter & cheaper More pollution Heavier & more expensive Both can be implemented using either 4 stroke or 2 strokeДў2 Classification Conventional Reciprocating Internal Combustion Engine By Mechanical Operation 4 Stroke Petrol (Otto) (SI) 2 Stroke Diesel (CI) By Thermodynamic Cycle Otto 4 Stroke Diesel 2 StrokeДЈ3 Cutoff ratio for the same compression ratio Thermal efficiency of the ideal Diesel cycle as a function of compression and cutoff ratios (k=1.4). More economical fuel consumption Less pollution More complicated mechanically Processes share strokes 1 cycle = 1 crank revolution 1 power stroke per crank rev. 18 Internal Combustion Engines multi-cylinder 14 cylinder Diesel engine (80 MW)ДЎ9 4 Stroke vs 2 Stroke Each process in own stroke 1 cycle = 2 crank revolution 1 power stroke per 2 crank rev.

Shauna banks internal combustion 4