ic engine and thermal VALVE TIMING ON CUT SECTION OF FOUR STROKE DIESEL ENGINEunit l.pptx

VALVE TIMING ON CUT SECTION OF FOUR STROKE
DIESEL ENGINE

1. Classification of Engines 1 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

2. Introduction to IC engines 2 Invented in early 1680 First attempt by Christian Huygens Converts heat energy produced by burning of fuel to mechanical output. Basically consists of a piston-cylinder arrangement. The expansion of air due to the heat produced moves the piston inside the cylinder . Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

3. Classification of IC Engine Based on cylinder Based on number of stroke Based on cooling Based on motion Based on cylinder arrangement Sentiment mining levels 3 Two Stroke Four Stroke Five Stroke Six Stroke Classification of IC engines Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Single Cylinder Multi Cylinder Air cooling Water cooling

4. Four Stroke 4 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Suction stroke Compression stroke Power stroke Exhaust stroke

5. Two Stroke 5 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Suction stroke - Power stroke Compression stroke - Exhaust stroke

6. Five Stroke 6 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S concept engine uses two high power (HP) fired cylinders with standard four-stroke engine power cycles. The exhaust gas from the two HP work cylinders is fed into a one larger central low pressure (LP) expansion cylinder. The hot exhaust is used to produce more power. 

7. Six Stroke 7 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S A six-stroke engine combines an internal combustion engine with a steam engine to turn some of the waste heat into power. The only catch is that you have to add a water tank to your car that's about the same size as the gas tank

8. Six Stroke 8 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S First Category Griffin six stroke engine Bajulaz six stroke engine Crower six stroke engine Velozeta six stroke engine Second Category Beare head six stroke engine Charge pump engine

9. Cylinder block Cylinder head Crankcase Oil sump or Oil pan Cylinder liners Piston Connecting rod Piston rings Crank shaft Cam shaft Spark plug Valves Valve mechanism Components of IC Engine

10. Cylinder block and Cylinder head

11. Piston and piston ring

12. Connecting Rod

13. Crank Shaft

14. Cam Shaft

15. Valve

16. Over Head Valve

17. Working of Four Stroke Cycle (Petrol) SI Engine

18. Working of Four Stroke Cycle (Diesel) CI Engine

19. Working of Two Stroke Cycle (Petrol) SI Engine

20. Single Cylinder Engine

21. A ir S t an d ar d , F ue l - A ir a n d A c t u al C y cles Otto cycle Diesel cycle Dual cycle Carnot Cycle Sterling Cycle Ericsson Cycle 1. Air Standard Cycle 2. Fuel Air Cycle 3. Actual Cycle

22. Otto cycle 1-2: Isentropic Compression 2-3: Constant Volume heat addition 3-4: Isentropic Expansion 4-1: Constant Volume heat rejection

23. Otto cycle

24. Diesel cycle

25. Diesel cycle

26. Difference between  Otto cycle and Diesel cycle OTTO CYCLE    DIESEL CYCLE Nicolas Otto in 1876.   Dr . Rudolph Diesel in 1897.   Uses the spark plugs to light the charge Does not require any assistance to get ignited , Petrol engines work on principle of Otto cycle Diesel engines work on the principle of diesel cycle The heat addition takes place at constant volume.   Heat is added at constant pressure.   The overall efficiency is way less than that of diesel cycle.   The overall efficiency is higher than the Otto cycle.   The charge is drawn in by the cylinders during the intake stroke.   After drawing air during the intake stroke, fuel is injected by an injector.   It has compression ratio from 7:1 to 10:1 It ranges from 11:1 to 22:1   It has a high thermal efficiency It has a comparatively lower thermal efficiency.

27. Dual cycle

28. Dual cycle Air Standard Efficiency and Mean effective pressure of Dual cycle can be calculated as follows : Consider 1 kg of air Heat addition at constant volume in process 2-3 = C v  (T 3  − T 2 ) Heat addition at constant pressure in process 3-4 = C p  (T 4  − T 3 ) Total heat added in process 2-3  and 3-4, q in  = [C p  (T 3  −T 2 ) − C v  (T 4  – T 1 )] Heat rejection at constant volume in process 5-1, q out   = C v  (T 5  – T 1 ) Net work done during cycle, w net   = q in   − q out   = [ C v  (T 3  − T 2 ) + C p  (T 4  − T 3 )] − C v  (T 5  − T 1 )

29. Dual cycle Air Standard Efficiency:

30. Carnot Cycle 30 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S 1-2 - I s oth e rmal E xp an s i on ( H e a t r e j e c t e d a t c o n s t . t e m p T 1 = T2 ) 2-3 - I s e n t r op i c E xp an s i on ( t h erm a l l y i n s u l a t e d a n d r eve rs i b l e a d i ab a t i c) 3-4 - I s o t h e rm a l Co mp r e ss i o n : He at i s t r a n s f e r red f r om a Hi gh t e mp e r a t u r e s o u r ce a t c o n s t a nt t e m pe rature T 3 4-1 - I s e n t r op i c Co mpr e ss i o n: E x pa n s i o n c o n ti nu es u n de r i s e ntro p i c ( t h erm a l l y i n s u l a t ed an d r ever s i b l e ad i a b a t i c)

31. Stirling Cycle 31 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S 1-2 Isothermal Compression (Heat rejected at constant temperature T1 = T2) 2-3 Constant Volume Compression and Heat Addition at V2 = V3 3-4 Isothermal Expansion: Heat is added and Gas expanded at constant temperature T3 4-1 Constant Volume Heat Rejection/ Expansion: Expansion continues at constant volume V4 = V1

32. Ericsson Cycle 32 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The Ericsson cycle is named after inventor John Ericsson, who designed and built many unique heat engines based on various thermodynamic cycles. He is credited with inventing two unique heat engine cycles and developing practical engines based on these cycles

33. Fuel-Air Cycle  I d e a l G a s C y c l e ( A i r S t a n d a r d C y c l e ) I de a l i zed p r o cess e s I de a l i ze w o rk in g Flui d   F u e l- A i r C y c l e I d e a l i z e d P r o c e s s e s A c c u r a t e W o r k i n g F l u i d M o d e l    A c t u a l E n g i n e C y c l e A c c u r a te M o d el s o f Pr o c e s A c c u r a te W ork in g F lui d Mod  

34. Fuel-Air Cycle

35. Fuel-Air Cycle Considerations 35 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The fuel-air cycle analysis takes into account the following: ( i ) The actual composition of the cylinder gases: the cylinder gases contains fuel, air, water vapour and residual gas. The fuel-air ratio changes during the operation of the engine which changes the relative amounts of CO, water vapour , etc. (ii) The variation in the specific heat with temperature: specific heat increase with temperature except for mono-atomic gases. Therefore, the value of γ also changes with temperature. (iii) The effect of dissociation: The fuel and air do not completely combine chemically at high temperature (above 1600 K) and this leads to the presence of CO, H 2 , H and O at equilibrium conditions. (iv) The variation in the number of molecules: the number of molecules present after combustion depends upon fuel-air ratio and on the pressure and temperature after the combustion.

36. Fuel-Air Cycle Considerations 36 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The following assumptions are commonly made: ( i ) There is no chemical change in either fuel or air prior to combustion. (ii) Subsequent to combustion, the charge is always in chemical equilibrium. (iii) There is no heat exchange between the gases and the cylinder walls in any process, i.e. they are adiabatic. Also the compression and expansion processes are frictionless. (iv) In case of reciprocating engines it is assumed that fluid motion can be ignored inside the cylinder. With particular reference to constant volume fuel-air cycle, it is also assumed that (v) The fuel is completely vaporized and perfectly mixed with the air. (vi) The burning takes place instantaneously at top dead centre ( at constant volume).

37. Properties of Fuel 37 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Selected SI input properties :   • Octane Number • Heat of Vaporization • Net Calorific Value • Auto Ignition Temperature • Carbon content    Selected CI input properties:   • Net Calorific Value • Cetane Number • Density • Viscosity • Oxygen content • Carbon content

38. Cylinder block Cylinder head Crankcase Oil sump or Oil pan Cylinder liners Piston Connecting rod Piston rings Crank shaft Cam shaft Spark plug Valves Carburetor Fuel Pump Components of SI Engine

39. Simple Carburetor 39 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The process of formation of a combustible fuel-air mixture by mixing the proper amount of fuel with air before admission to engine cylinder is called carburetion and the device which does this job is called a carburetor. Factor affecting the carburetor: Engine speed Vaporization characteristics Temperature of in coming air Design of carburetor

40. Simple Carburetor 40 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The components of the carburetor consist of: Float chamber Float valve Jet nozzle Venturi Throttle valve Accelerator pedal Choke Fuel tank Fuel pump Fuel Filter

41. CARBURETOR PERFORMANCE 41 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S The air/fuel ratio delivered by this carburetor is the stoichiometric air /fuel ratio. The performance of the elementary carburetor. Once fuel starts to flow, a consequence of these variations the flue flow rate increases more rapidly than the air flow rate. The carburetor delivers a mixture of fuel/air equivalence ratio as the flow rate increases. Suppose the venturi and orifice is sized to given a stoichiometric mixture at an air flow rate corresponding to 1KN/m2 veturi pressure drop.

42. 42 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Anti-diesel i ng system Richer Coasting System A c cele r ation Pump system Economizer or P ower Enrichment sy s tem Additional systems in Modern c a rbu r etors

43. 43 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S SI engine somtime contin u ous runs e ven after ignition stopped. This causes misfire condi t ion. This p henomena ca l led Dieseling (af t er running or run on .) In mode r n cars when car i s running at maximum a c cele r ation and a c cele r ator p edal is sudden l y release d . The wheel will run engine a t higher rpm, b u t Consequen t ly the va c cum at inlet and out l et chamber increases too much and t his causes incomplete combust i on. Anti dieseling system Richer Coasting System

44. 44 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S In order to accelerate the vehicle quickly here mixture required is rich. This r ichness depends upon the v acuum created in throttle. In o r der to increase mixture richness the fuel has to be obtained very quickl y . This everyt h ing has to be do n e very rapidly and quickl y . If t h rottle is sudden opend ,it inc r eases the air flo w . But due t o inertia o f gasoline fluid it comes out in certain am o unt o nly from fuel chambe r .this causes lean mixture and e n gine to misfire. A c celerati o n Pump system At the maximum power range of 80% to 90% load, the air fuel ratio has to be about 12:1 to 14:1. But air fuel ration 12:1 is expected always during maximum power . Economizer or power Enrichment system

45. 45 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Zenith Carburetor Solex Carb u retor Carter Carb u rator T ypes of d ifferent modern carburators

46. 46 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Zenith Carburetor Solex Carb u retor Carter Carb u rator T ypes of d ifferent modern carburators

47. Air Fuel Mixture Requirement 47 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S An engine is generally operated at different load and speed. For this proper air fuel mixture should be supplied to the engine cylinder. Fuel and air are mixed to form three different type of mixtures. Chemically corrected mixture(15:1) Rich mixture (12:1 to 10:1) Lean mixture (17:1 to 20:1)

48. Air Fuel Ratio Mixture For Gasoline 48 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Rich Mixture to burn Excess Fuel Excess Air Air Fuel Ratio Lean Mixture to burn 15 8 19

49. Mixture Requirement At Different Load And Speed 49 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

50. Automotive air fuel Mixture Requirement 50 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Idling ( mixture must be enrich) Cruising ( mixture must be lean) High power ( mixture must be enrich)

51. Combustion in SI engine 51 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S In a n y co n vent i o n al spark-ig n iti o n ( SI) e n gi n e , the fu e l an d ai r are h o m o g e n e o u sly mixed to g et h er in the in t ake sy s te m , in d ucted thr o u g h the i n take valve in t o t he cylind e r where it m ixes with resid u al g a ses a nd is th e n co m pr e s s e d . Und e r n o rmal o p er a ti n g co n di t io n s, combustion is initiated towards the end of the compression stroke at the spark plug by an electric discharge.

52. Stages of Combustion in SI engine 52 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Compression (a - b) Combustion (b - c) Expansion (c - d)

53. Stages of Combustion in SI engine 53 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S A is the point of passage of spark (say 20° bTDC ), B is the point at which the beginning of pressure rise can be detected (say 8°bTDC) C the attainment of peak pressure. Thus AB represents the first stage, BC the second stage and CD the third stage

54. Stages of Combustion in SI engine 54 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

55. Flame propagation 55 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Two important reason for flame front across the combustion chamber. Reaction rate Transposition rate Two important factor for flame speed Turbulence Air fuel ratio Temperature and Pressure Compression ratio Engine output Engine speed Engine size

56. Normal and Abnormal Combustion 56 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Normal Combustion Abnormal Combustion When the flame travels evenly or uniformly across the combustion chamber. When the combustion gets deviated from the normal behaviour and resulting in loss of performance or damaging the engine

57. Normal and Abnormal Combustion 57 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S If the temperature of the end charge had not reached its self ignition temperature , the charge would not auto-ignite and the flame will advance further and consume the charge BB‘D.

58. Normal and Abnormal Combustion 58 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S If the final temperature is greater than and equal to the auto-ignition temperature , the charge BBD auto ignites (knocking)

59. FACTORS AFFECTING KNOCK 59 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Decreasing the compression ratio or reducing the inlet pressure Decreasing the inlet air temperature Decreasing coolant inlet air temperature Retarding spark timing Decreasing the load Increasing octane rating of the fuel supplying rich or lean mixtures Increasing the humidity of the entering air Stratifying the mixture so that the end gas is less reactive Increasing the turbulence of the mixture and thus increasing the flame speed.

60. Performance Test on IC Engine 60 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Commercial test Lubricating oil Consumption Valve and port timing Cooling water consumption Overload carrying capacity Thermodynamics test Indicated mean effective pressure Indicated power Speed of the engine Brake power Mechanical losses Mechanical efficiency Fuel consumption Air consumption Thermal efficiency Volumetric efficiency Heat balance sheet

61. Performance Test on IC Engine 61 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Indicated mean effective pressure = be the area of positive loop = be the area of negative loop = be the actual length of diagram  

62. Performance Test on IC Engine 62 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Indicated power = indicated mean effective pressure = length of the stroke = be the actual length of diagram N- number of working stroke per second K= Number of cylinder  

63. Performance Test on IC Engine 63 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Brake power Prony brake Rope brakes = 2 NWR   = be the net load on the brake = be the effective radius of the brake drum = be the Speed of the engine   = 2 NWR    

64. Performance Test on IC Engine 64 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Friction power Willan’s line method Motoring test Deceleration method Difference between IP and BP

65. Performance Test on IC Engine 65 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Willan’s line method

66. Mores test or measurement of IP of Multi Cylinder Engine 66 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S , , = Indicated power of the each individual cylinder , , = Friction power of the each individual cylinder , B , = Brake power of the each individual cylinder   = IP-BP Total brake power = ( + + ) - ( ) When the cylinder is cut off IP 1 =0 but the friction power is same BP of the remaining three cylinder = ( + + ) - ( ) IP 1 = BP- Similarly IP 2 = BP- IP 3 = BP- IP 4 = BP-  

67. Mores test or measurement of IP of Multi Cylinder Engine 67 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Indicated thermal efficiency= Heat supplied = Indicated thermal efficiency= Brake thermal efficiency = Indicated thermal efficiency= Relative efficiency = Volumetric efficiency = Specific fuel Consumption =  

68. Heat balance test 68 Q s = X CV in kJ/h Q BP = = 2 NWR in kJ/h Q IP = in kJ/h Heat rejected by cooling water= Q w = in kJ/h Heat carried away by exhaust gas = Q g = in kJ/h = Specific heat capacity of gas in kJ/kg K = 1.005 KJ/kg K = mass of exhaust gas in kg/h Unaccounted heat loss = Q ua = Q s ) in kJ/h Percentage of heat loss X 100   = mass of cooling water circulated in kg/h = Specific heat capacity of water in kJ/kg K = 4.19 KJ/kg K = be the inlet temperature in K = be the outlet temperature in K  

69. Heat balance test 69 Credit KJ % Debit KJ %

70. Performance Test on IC Engine Re = Effective radius of brake drum in meters Then, Re= (radius of brake drum+ dia of rope)

71. Performance Test on FIELD MARSHAL Engine

72. Heat Balance Test On IC Engine

73. Heat Balance Test On Four Stroke Diesel Engine

74. Heat Balance Test On Four Stroke Diesel Engine

75. Heat Balance Test On Four Stroke Diesel Engine

76. Petrol injection system 76 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Petrol injection system Gasoline direct injection (GDI) Indirect injection ( manifold injection) Single point injection or Throttle injection Multi point fuel injection (MPFI ) or Port injection

77.  In indirect fuel is injected into the air stream before entering the combustion chamber.  And in direct injection system fuel is injected directly inside the combustion chamber. Fuel injector Indirect injection Direct injection C ombustion Chamber Inlet valve Petrol injection system

78. Single point injection or Throttle injection system 78 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S 1 – Fuel supply 2 – Air intake 3 – Throttle 4 – Intake manifold 5 – Fuel injector (or injectors) 6 – Engine

79. Single point injection or Throttle injection system 79 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Air Mixture of air and gasoline RPM sensor Intake manifold vacuum sensor Engine Injector ECU Injector volume control Gasoline Injection into intake manifold

80. Multi point fuel injection (MPFI) or Port injection system 80 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S 1 – Fuel supply 2 – Air intake 3 – Throttle 4 – Intake manifold 5 – Fuel injector (or injectors) 6 – Engine

81. Multi point fuel injection (MPFI) or Port injection system 81 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Air Mixture of fuel and air RPM sensor Air flow sensor Engine Injector ECU Injector volume control Gasoline Injection near port

82. Direct Injection system (GDI) 82 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S 1 – Fuel supply 2 – Air intake 3 – Throttle 4 – Intake manifold 5 – Fuel injector (or injectors) 6 – Engine

83. Ignition Systems 83 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Basically Convectional Ignition systems are of 2 types : (a) Battery or Coil Ignition System, and (b) Magneto Ignition System. Battery ignition system was generally used in 4-wheelers, but now-a-days it is more commonly used in 2-wheelers In this case 6 V or 12 V batteries will supply necessary current in the primary winding. Magneto ignition system is mainly used in 2-wheelers, kick start engines.

84. Battery or Coil Ignition System 84 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S It mainly consists of a 6 or 12 volt battery, ammeter, ignition switch, auto-transformer (step up transformer), contact breaker, capacitor, distributor rotor, distributor contact points, spark plugs.

85. Magneto Ignition System 85 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

86. Electronic Ignition Systems 86 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Electronic Ignition System is as follow : (a) Capacitance Discharge Ignition system ( b) Transistorized system (c) Piezo -electric Ignition system ( d) The Texaco Ignition system

87. Capacitance Discharge Ignition system 87 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S

88. Transistorized system 88 Dr.V.MANIENIYAN , Asst. Professor of Mechanical Engg , GCE-S Piezo ignition is a type of ignition that is used in portable camping stoves, gas grills and some lighters, and potato cannons. Piezo ignition uses the principle of piezoelectricity, which, in short, is the electric charge that accumulates in some materials in response to high pressure. It consists of a small, spring-loaded hammer which, when a button is pressed, hits a quartz crystal. Quartz is piezoelectric, which means that it creates a voltage when deformed. This sudden forceful deformation produces a high voltage and subsequent electrical discharge, which ignites the gas. No external electric connection is required, though wires are sometimes used to locate the sparking location away from the crystal itself. Piezo ignition systems can be operated by either a lever, push-button or built into the control knob. An electric spark is usually generated once per turn of the knob or press of the button.