Introduction to ic engines


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IC engines, Classification , Application

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Introduction to ic engines

  1. 1. Chapter I Introduction to IC Engines By Dr. S. Murali Professor & Head Dept. of Mechanical Engineering
  2. 2. Thermodynamics •Branch of science which deals with H t B h f i hi h d l ith Heat and Work •Basic principles B i i i l –Zeroeth law • Basis for Temperature measurement –First Law • Conversion of Energies –Second Law • Rectifies flaws in First Law • Basic theories for Heat Engines development
  3. 3. Engine & Heat Engine Engine : D i used t convert one form E i Device d to t f of energy another form of energy. A heat engine diverts some heat as it flows naturally from hot to cold and converts that heat into useful work Heat Engine: (i) Internal combustion engine (ii) External combustion engine
  4. 4. Internal Combustion engine
  5. 5. External Combustion engine
  6. 6. IC Engine(Reciprocating) Gudgeon pin Cylinder Cooling Jacket Crank Shaft Crank Web Crankcase
  7. 7. Reciprocating IC Engine(Parts) • Pi t Piston- cylindrical piece of metal th t moves li d i l i f t l that up and down the cylinder. • Piston rings rings provide a sliding seal ringsbetween the piston and cylinder. • Rings serve two purposes: –prevent fuel/air from leaking into the sump –prevent oil from entering the combustion chamber0 •Combustion chamber- area where combustion and compression takes place.
  8. 8. Reciprocating IC Engine(Parts) •Connecting rod- connects th piston t the C ti d t the i t to th crankshaft. •Crankshaft- th crankshaft turns the up C k h ft the k h ft t th and down motion of the piston into circular motion •Sump- (oil pan) contains and collects oil for lubrication
  9. 9. IC Engine Terminology Clearance Top dead center (TDC) Stoke (L) Bottom dead center (BDC) Cylinder B C li d Bore (D) π Displacement or Stroke Volume (Vs ) = A × L = D 2 L 4 Cylinder Volume (V ) C li d V l = dispacement volume + clearance volume = VS + VC VS V VC + VS Compression Ratio(r ) = p = = 1+ VC VC VC
  10. 10. CLASSIFICATION OF IC ENGINES 1. 1 Application 2. Basic Engine Design 3. Operating Cycle 4. Working Cycle 5. Valve/Port Design and Location 6. Fuel 7. Mixture Preparation 8. Ignition 8 I iti 9. Stratification of Charge 10. 10 Combustion Chamber Design 11. Method of Load Control 12. Cooling g
  11. 11. CLASSIFICATION OF IC ENGINES Application 1. Automotive: () (i) Car (ii) Truck/Bus (iii) Off-highway 2. 2 Locomotive 3. Light Aircraft 4. Marine: (i) Outboard (ii) Inboard (iii) Ship 5. Power Generation: (i) (ii) Portable (Domestic) Fixed (Peak Power)
  12. 12. Application
  13. 13. CLASSIFICATION OF IC ENGINES 6. 6 Agricultural: (i) (ii) 7. Earthmoving: (i) (ii) (iii) 8. Home U 8 H Use: (i) (ii) (iii) 9. Others Tractors Pump sets Dumpers Tippers Mining Equipment Lawnmowers Snow blowers Tools
  14. 14. Application
  15. 15. CLASSIFICATION OF IC ENGINES Basic Engine Design Design: 1. Reciprocating (a) Single Cylinder (b) Multi-cylinder (I) In-line (ii) V (iii) Radial (iv) Opposed Cylinder (v) Opposed Piston 2. R t 2 Rotary: (a) Single Rotor ( ) Si l R t (b) Multi-rotor
  16. 16. Basic Engine Design Vertical Horizontal Slanted
  17. 17. Basic Engine Design In-line V Horizontally opposed
  18. 18. Basic Engine Design
  19. 19. CLASSIFICATION OF IC ENGINES • • • • • Operating Cycle O ti C l Otto (For the Conventional SI Engine) Atkinson (For Complete Expansion SI Engine) Miller (For Early Mill (F E l or L t I l t Valve Late Inlet V l Closing type SI Engine) Diesel (For the Ideal Di Di l (F th Id l Diesel Engine) lE i ) Dual (For the Actual Diesel Engine)
  20. 20. CLASSIFICATION OF IC ENGINES Working C cle (St okes) Wo king Cycle (Strokes) 1. Four Stroke Cycle: (a) Naturally Aspirated (b)Supercharged/Turbocharged 2. 2 Two Stroke Cycle: (a) Crankcase Scavenged (b) Uniflow Scavenged (i) Inlet valve/Exhaust Port (ii) Inlet Port/Exhaust Valve (iii) Inlet and Exhaust Valve ay b a u a y sp a d May be Naturally Aspirated Turbocharged
  21. 21. CLASSIFICATION OF IC ENGINES 1. 2. 2 3. 4. 4 1. 1 2. 3. 4. Valve/Port Val e/Po t Design Poppet Valve Rotary Valve Reed Valve Piston Controlled Porting Valve Location The T-head T head The L-head The F-head F head The I-head: (i) Over head Valve (OHV) (ii) Over head Cam (OHC) ( ) O ad Ca (O C)
  22. 22. CLASSIFICATION OF IC ENGINES Fuel 1.Conventional: (a) Crude oil derived (i) Petrol (ii) Diesel (b) Other sources (i) Coal (ii) Wood (i l d bi W d (includes bio-mass) ) (iii)Tar Sands (iv)Shale
  23. 23. CLASSIFICATION OF IC ENGINES Fuel 2. Alternate: (a) Petroleum derived (i) CNG(Compressed Natural Gas) (ii) LPG(Liquid Petroleum Gas) (b) Bio-mass Derived (i) Alcohols (methyl and ethyl) (ii) Vegetable oils V t bl il (iii) Producer gas and biogas (iv) Hydrogen 3. Blending 4. Dual fueling g
  24. 24. CLASSIFICATION OF IC ENGINES Mixture P Mi t Preparation ti 1. Carburetion 2. Fuel Injection (i) Diesel (ii) Gasoline (a) Manifold (b) Port (c) Cylinder
  25. 25. CLASSIFICATION OF IC ENGINES Ignition I iti 1. Spark Ignition (a) Conventional (i) Battery (ii) Magneto (b) Other methods 2. Compression Ignition
  26. 26. CLASSIFICATION OF IC ENGINES Charge Stratification Ch St tifi ti 1. Homogeneous Charge (Also Pre-mixed charge) 2. Stratified Ch 2 St tifi d Charge (i) With carburetion (ii) With fuel injection
  27. 27. CLASSIFICATION OF IC ENGINES 1. 2. Combustion Chambe Comb stion Chamber Design Open Chamber (i) Disc type (ii) Wedge (iii) Hemispherical (iv) Bowl-in-piston (v) Other design Divided Chamber (For CI) (For SI) (i) Swirl chamber (i) CVCC (ii) Pre-chamber ( ) a b (ii) Other designs ( )O d sg s
  28. 28. CLASSIFICATION OF IC ENGINES Method f L d Control M th d of Load C t l 1. Throttling: (To keep mixture strength constant) Al called Ch t t) Also ll d Charge Control C t l Used in the Carbureted S.I. Engine 2. Fuel C t l (To 2 F l Control (T vary th mixture the i t strength according to load) Used in th C I E i U d i the C.I. Engine 3. Combination Used in the F l i j t d S.I. E i U d i th Fuel-injected S I Engine.
  29. 29. CLASSIFICATION OF IC ENGINES Cooling 1. 1 Direct Air cooling Air-cooling 2. 2 Indirect Air-cooling (Liquid Cooling) 3. 3 Low Heat Rejection (Semi-adiabatic) (Semi adiabatic) engine.
  30. 30. CLASSIFICATION OF IC ENGINES Cooling 1. 1 Direct Air cooling Air-cooling 2. 2 Indirect Air-cooling (Liquid Cooling) 3. 3 Low Heat Rejection (Semi-adiabatic) (Semi adiabatic) engine.
  31. 31. Cooling
  32. 32. Working of Four Stroke SI Engine Sequential operations S i l i •Induction Stroke: fill cylinder with air fuel mixture •Compression Stroke: squeeze mixture •Power Stroke: burn and extract work •Exhaust Stroke: empty cylinder of exhaust
  33. 33. Induction Stroke(1→2) • Piston moves from TDC to BDC • Intake valve - open • Exhaust valve- closed • Engine pulls piston out of cylinder • Low pressure inside cylinder • air fuel mixture (carburretted 14 to 15 on weight basis) enters into cylinder • Flywheel angle of rotation 0-180 • Engine does work on the gases during this stroke
  34. 34. Compression Stroke(2→3) • Piston moves from BDC to TDC • Intake valve – closed • Exhaust valve- closed • Engine pushes piston into cylinder • Mixture is compressed to high pressure and temperature • Flywheel angle of rotation 180-360 • Engine does work on the gases during this stroke
  35. 35. Power Stroke(3→4) • Piston moves from TDC-BDC • Intake valve - closed • Exhaust valve - closed • Mixture burns to form hot gases • Gases push piston out of cylinder • Gases expand to lower pressure and temperature • Flywheel angle of rotation 360-540 • Gases do work on engine during this stroke
  36. 36. Exhaust Stroke • Piston moving up • Intake valve closed • Exhaust valve open • Engine pushes piston into cylinder • High pressure inside cylinder • Pressure pushes burned gases out of cylinder • Flywheel angle of rotation 540-720 • Engine does work on the gases during this stroke
  37. 37. SI Engine Animation & Ideal PV-Diagram 3 1 2 3 4 1 intake isentropic compression isochoric h ti i h i heating isentropic expansion 0 exhaust ignition P 0 1 2 3 4 2 Patm 0 1 exhau ust 4 Intake / exhaust V2 V1 V
  38. 38. Working of 4 stroke CI Engine • operation i quite similar t SI engine ti is it i il to i –However • F l Injectors are used for Fuel I j t df atomized fuel injection • Fresh air is entered during induction stroke g • Heterogeneous mixture is burned because of self ignition of the fuel
  39. 39. Working of 4 stroke CI Engine 0 → 1induction 1 → 2 isentropic compression 2 → 3const. vloume heat addition 3 → 4 isentropic exp ansion 4 → 1 → 0 const. pressure heat j ti h t rejection 0 Intake / exhaust
  40. 40. Salient features of 4 stroke engine •Provided with valves P id d ith l •It requires four strokes •Two revolution of crank shaft •One power stroke for every four strokes •Flywheel stores energy during power stroke and supplies part of energy for idle strokes
  41. 41. SI engine Vs CI engine Description Basic Cycle Fuel Introduction f I t d ti of Fuel SI CI Otto cycle or constant Diesel cycle or volume heat addition cycle constant pressure heat addition Gasoline, a highly volatile Diesel, a non volatile , g y , fuel, high self ignition fuel, low self ignition temperature temperature A mixture of fuel and air is F l i injected just at i t f f l d i i Fuel is i j t d j t t introduced during suction the end of compression stroke(Induction Stroke) stroke Load control Quantity governed Quality governed Fuel Ignition g Requires Spark plug q p p g Self ignition g
  42. 42. SI engine Vs CI engine(contd) Description Compression ratio Thermal efficiency y Weight SI CI 6-10 16-20 Low efficiency(Lower compression ratio) p ) Higher efficiency(higher y( g compression ratio) Heavier(higher peak pressure) ) Lighter in weight(low peak pressure) k )
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