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Energy Systems for Surface Transport

Energy Systems for Surface Transport. P M V Subbarao Professor Mechanical Engineering Department I I T Delhi. Reciprocating Positive Displacement Energy Systems !!!. Forces to be Overcome by an Automobile. Resistance Forces on A Vehicle.

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Energy Systems for Surface Transport

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  1. Energy Systems for Surface Transport P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Reciprocating Positive Displacement Energy Systems !!!

  2. Forces to be Overcome by an Automobile

  3. Resistance Forces on A Vehicle • The major components of the resisting forces to motion are comprised of : • Inertial or Tansient forces (Ft= ma & I forces) • Aerodynamic loads (Faero) • Gradeability requirements (Fgrade) • Chassis losses (Froll resist ).

  4. Cyclic Work To be Delivered by An Artificial Horse Ideal cycle work to be provided by A Powering Engine: The speed of the engine for a given vehicle speed in km/h is: Time available for completion of a cycle (Four stroke Model for Engine):

  5. The Art of Positive Displacement Work • Onset of displacement of system provokes the process. • The rate of change in instantaneous displacement controls, decides the rates of changes of other thermodynamic variables. • The brain of an animal controls the strain rates in Muscles….. • How to design the basic brain of these devices?

  6. The Geometrical Description of Piston- Cylinder Mechanism

  7. Engine Geometric Ratios Engine Compression Ratio Cylinder Bore-to-Stroke Ratio Kinematic Rod Ratio

  8. Selection of Bore-to-stroke Ratio 18,000 rpm 102 rpm

  9. Engine Kinematics Instantaneous Volume of system Relative location of piston center w.r.t . Crank Axis at any crank angle

  10. Positive Displacement Hardware to Execute A Process For a general thermodynamic process:

  11. Positive Vs Negative Work Transfer Process Work input: Work output: There is a need for invention of A Cycle !!!

  12. Cyclic Work To be Delivered by An Artificial Horse Ideal cycle work to be provided by A Powering Engine:

  13. Otto’s Model for Mobile Power Units • Nicolaus Otto's first occupation was as a traveling salesman selling tea, coffee, and sugar. • He soon developed an interest in the new technologies of the day and began experimenting with building four-stroke engines. • After meeting Eugen Langen, a technician and owner of a sugar factory, Otto quit his job, and in 1864, the duo started the world's first engine manufacturing company N.A. Otto & Cie (now DEUTZ AG, Köln). • In 1867, the pair were awarded a Gold Medal at the Paris World Exhibition for their atmospheric gas engine built a year earlier.

  14. Otto’s Definition of Displacement Work Devices FUEL A I R Ignition Fuel/Air Mixture Combustion Products Intake Stroke Compression Stroke Power Stroke Exhaust Stroke Spark Ignition Engine

  15. Displacement Work Devices : Spark Ignition Engine FUEL A I R Ignition Fuel/Air Mixture Combustion Products Intake Stroke Compression Stroke Power Stroke Exhaust Stroke

  16. Qin Qout Air Otto Cycle TC BC Compression Process Const volume heat addition Process Expansion Process Const volume heat rejection Process Active Part of the Innovation

  17. Simplified Thermodynamic Cycles • All the properties of working substance (air) are taken to be constant. • This is known as Air-standard analysis. • Simplifications to the real cycle include: 1) Intake and exhaust processes not considered 2) Fixed amount of air (ideal gas) for working fluid 3) Combustion process not considered 4) Engine friction and heat losses not considered 5) Specific heats independent of temperature

  18. Otto’s Model for Engine cycle Process 1 2 Isentropic compression Process 2  3 Constant volume heat addition Process 3  4 Isentropic expansion Process 4  1 Constant volume heat rejection Compression ratio: Qin Qout TC v1 BC v2 TC BC

  19. First Law Analysis of Cycle Net cycle work: Cycle thermal efficiency:

  20. Clue to Achieve Higher Efficiency

  21. Measure of Size & Feasibility AIR P 3 Qin 4 Wcycle 2 1 V2 V1

  22. Factors Affecting Work per Cycle Work The net cycle work of an engine can be increased by either: i) Increasing the r (12’) ii) Increase Qin (23”) 3’’ P (ii) 3 4’’ 3’C Qin 4 Wcycle 4’C 2 (i) 1 2’ V2 V1

  23. Creation of Compact Engines Using Otto Cycle (200 CC) Qin = 500J/cycle) MEP, MPa Qin = 200J/cycle) Qin = 100J/cycle) rv

  24. The Art of Down Sizing an Engine

  25. Important Accessories for SI Engine

  26. Fuel Induction System for Otto’s Engines • The first generation fuel Induction system used in SI engine is named as Carburetors.

  27. Thermo-flow Model for Carburetor 1

  28. In search of Ignition systems • Ignition by flame or hot jet • Ignition by an electrically heated wire • Spark Ignition System • Plasma jet ignition • Photochemical ignition • Microwave ignition • Laser ignition • Puff-jet ignition February 21, 2015: Laser ignition demonstrated in a real engine could boost engine efficiency by 27%.

  29. Ignition System : The Extreme Art of Miniaturization • The average lightning bolt measures about an inch wide and five miles long. • The temperature of lightning can reach around 30,000 K. • The electricity in a single bolt can reach 200 million volts. • An average duration of time for a stroke of lightning is about 30 microseconds. • The average peak power of a stroke of lightning is about 1012 watts. • A single bolt of lightning carries an energy 5 billion joules. Spark plugs in automobiles generally have a gap between 0.6 and 1.8 mm

  30. Simplified electrical scheme of a coil ignition system The evolution of the electrical energy of the secondary circuit The energy is not entirely transferred to the spark: a substantial part is lost by Joule effect.

  31. Mechanism of Spark Creation ii) breakdown i) pre-discharge 15kV (1mJ) 50V

  32. Mechanism of Spark Development iv) arc 15kV (1mJ) 50V (1mJ)

  33. Mechanism of Spark Development v) arc/glow transition iv) arc 500V (30mJ) 50V (1mJ) 15kV (1mJ) vi) glow

  34. Mechanism of Spark Development ii) breakdown i) pre-discharge v) arc/glow transition vi) glow iv) arc iii) breakdown/arc transition 500V (30mJ) 50V (1mJ) 15kV (1mJ)

  35. The Historical Event in Automobiles • In 1893, the Benz Velo became the world's first inexpensive, mass-produced car. • 12000 unites were produced. • 0.7 hp and 958cc!!! • The Mercedes 35 HP (German: Mercedes 35 PS) was a radical early car model designed in 1901. • Engine volume: 5,918CC. • The racecar was of a disappointing performance by multiple technical complications and enduring just for few laps.

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