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20 th Century Inventions for Automotive Prime Movers based on Diesel’s Model. P M V Subbarao Professor Mechanical Engineering Department. Methods of Building a Rational & Powerful Artificial Horse…. Thermo-chemical Feasibility of Otto’s Model.
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20th Century Inventions for Automotive Prime Movers based on Diesel’s Model P M V Subbarao Professor Mechanical Engineering Department Methods of Building a Rational & Powerful Artificial Horse….
Engine Damage From Severe Knock Damage to the engine is caused by a combination of high temperature and high pressure. Piston crown Piston Aluminum cylinder head Cylinder head gasket
Critical Compression Ratio Formula Name Critical r CH4 Methane 12.6 C3H8 Propane 12.2
Irrationality of Otto’s Model Typical SI engines 9 < r < 11 Fuel/Air Mixture k = 1.4 Compression Stroke
Rudolf Christian Karl Diesel • Diesel was born in Paris, France in 1858 the second of three children of Elise and Theodor Diesel. • At age 14, Rudolf wrote a letter to his parents stating that he wanted to become an engineer. • In 1893, He began designing an engine based on the Carnot cycle, and in 1893, Diesel published a treatise entitled Theorie und Konstruktion eines rationellen Wärmemotors zum Ersatz der Dampfmaschine und der heute bekannten Verbrennungsmotoren.
Diesel’s Rational Engine • Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and Combustion Engines Known Today. • This formed the basis for his work on and invention of, the diesel engine. • Eventually he obtained a patent for his design for a compression-ignition engine. In his engine, fuel was injected at the end of compression and the fuel was ignited by the high temperature resulting from compression.
Thermal Efficiency rc=1 rc=2 rc=3 Typical CI Engines 15 < r < 20 When rc (= v3/v2)1 the Diesel cycle efficiency approaches the efficiency of the Otto cycle
Multi Cylinder Diesel engines • 1897 -- Diesel built the first diesel engine at the Augsburg Maschinenfabrik . • 1898 -- Rudolph Diesel, filed a patent application • The single cylinder engine was used to power stationary machinery. • It weighed five tonnes and produced 20 hp at 172 rpm! • The engine operated at 26.2% efficiency, a very significant improvement on the 20% achieved by the best gasoline engines of the time. • 1922 Benz introduces a 2-cylinder, 30 hp 800 rpm tractor engine. • 1924 Benz introduces a 4-cylinder, 50 hp 1000 rpm truck engine. • 1960- 1970 Peugeot introduced the 404 Diesel followed by the 504 Diesel and the 204 Diesel, the first diesel-powered compact car
The world’s biggest engine : Wärtsilä-Sulzer RTA96. :May 2015 14-cylinder, 2-stroke turbocharged Diesel engine. Weight : 2.3 million kgs Speed : 102 rpm powering the Emma Maersk It has now become cheaper to transport goods from China to a US port than to transport the same goods from a US port to the final destination inland of US by a truck.
Components of Entropy generation mechanisms in CI engines • The Global Entropy generation contains the following sub-processes: • Spray development • Air entrainment and mixing • Droplet evaporation • Auto Ignition • Combustion and thermodynamic Processes • Heat transfer among various parts (Zones) of Cylinder • Formation of Particulates & NOx • Variation of Chemical compositions • Variation of gas properties
Ignition Delay • The sum of times required for sub process preceding the ignition. • The most widely reported correlation relating the ignition delay to the ambient gas condition is given by the relation where τig is the ignition delay, pgand Tg are the ambient gas mean pressure and temperature before autoignition takes place, A, B and n are experimental constants.
Arhenius-type equation for Ignition Delay • An Arhenius type equation for Ignition delay is: p :Premixed air fuel ratio.
Temporal evolution of Combustion in Each Zone Start of injection End of injecction 10 30 -20 -10 TC 20
Experimental Study of Combustion Process In above Eq., the rate of the heat loss Qloss/dθ is expressed as: The convective heat transfer coefficient is given by the Woschni model as For combustion and expansion processes: C1=0.00324.
Schematic of a diesel spray & flame with temperatures and chemistry
Development of Injection Pressure & Injection System in CI Engines
Common Rail Diesel Injection System The Common Rail Diesel Injection System delivers a more controlled quantity of atomised fuel, which leads to better fuel economy; a reduction in exhaust emissions; and a significant decrease in engine noise during operation.
