Prakhar Srivastava, profile picture
Uploaded byPrakhar Srivastava
PPT, PDF3,950 views

24514675 2-internal-combustion-engine

This document provides information on diesel propulsion systems and two-stroke diesel engines. It begins with learning objectives about familiarizing students with marine diesel engines. It then describes the operating cycles of internal combustion engines, including the Otto, Diesel, and dual cycles. It explains the four-stroke cycle and two-stroke cycle of compression ignition engines. Details are provided on the intake, compression, power, and exhaust strokes. The timing diagrams of the four-stroke and two-stroke cycles are illustrated. Valve timing and overlapping are also discussed.

Embed presentation

Downloaded 225 times
MTM 3202 Diesel propulsion systems
Diesel propulsion systems
INTERNAL COMBUSTION ENGINES
• Course Learning Objective: Familiarize students to the basic cycle and design features of modern marine diesel engines Specific Objectives: - Define the theory and principle of Internal Combustion Engine - Describe basic operations of working cycle - Identify the engine timing diagram - Describe differences and advantages of 2S & 4S
Principle of I.C.E • An internal combustion engine is one in which the fuel is burnt within the engine -> usually of the reciprocating type. • It involve system where combustion of the fuel and the conversion of the heat energy from combustion to mechanical energy takes place within the cylinders (ICE)
I.C.E. CATEGORIES – Spark ignition engines use gaseous or volatile distillate fuels -> work on a modified Otto cycle -> operate on the 2 or 4 – stroke cycle. – Compression ignition engine use distillate liquid fuels -> work on either 2 or 4 – stroke cycle and normally designed to operate on the dual-combustion cycle (Otto and Diesel cycle)
Otto cycle • In the Otto cycle the theoretical pressure – volume diagram is formed from : two constant – volume and two adiabatic processes. • The air in the cylinder is compressed adiabatically. • Heat is added to the air at constant volume -> Work is done during the adiabatic expansion and -> then heat is rejected at constant volume
Otto Cycle Pressure (Pa) C P2 D P1 B A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant volume (combustion) C–D : Adiabatic expansion D–A : Heat rejected at constant volume (exhaust)
Otto Cycle • 1. The induction stroke takes place at A.  Although in theory the pressure should be the same as atmospheric, in practice it's rather lower.  The amount of petrol air mixture taken in can be increased by use of a supercharger. • 2. A to B is the compression stroke.  Both valves are closed.  The compression is adiabatic, and no heat enters or leaves the cylinder.  • 3. Ignition occurs at C.  The gases resulting from the ignition expand adiabatically, leading to the power stroke. • 4. D to A the gas is cooled instantaneously.   • 5. At A the exhaust stroke occurs and the the gases are removed at constant pressure to the atmosphere. • 6. Strange as it may seem, the piston does half a revolution at A.  Actually it's slightly in practice, as the the valve timing is more complex.
Diesel cycle • In the diesel cycle the theoretical pressure- volume diagram is formed from two adiabatic operations, one constant-pressure and one constant-volume operation. • Air is compressed adiabatically, then heat is added at constant pressure. Adiabatic expansion takes place and then heat is rejected at constant volume
Diesel Cycle Pressure (Pa) B C P D A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant pressure (combustion) C–D : Adiabatic expansion D–A : Heat rejected at constant volume
Diesel cycle • 1. The induction stroke takes air in ideally at constant volume, pressure at temperature. • 2. The compression stroke takes place from A to B.  The air is compressed adiabatically to about 1/20 of its original volume.  It gets hot. • 3. From B to C fuel is injected in atomised form.  It burns steadily so that the pressure on the piston is constant. • 4. From C to D the power stroke moves the piston down as adiabatic expansion takes place. • 5. D to A cooling and exhaust occurs.
Dual cycle • In the dual cycle, air is compressed adiabatically, then heat is added, partly in a constant volume process and the remainder in a constant pressure process. • Expansion takes place adiabatically and then heat is rejected at constant volume
Pressure (Pa) C D P E B A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant volume C–D : Heat received at constant pressure D–E : Adiabatic expansion E–A : Heat rejected at constant volume
COMPRESSION IGNITION ENGINE • Compression ignition engine works on dual cycle • The fresh air enters each of the engine cylinders and is compressed by the upward movement of the piston. • The compression causes the temperature and pressure of the fresh air to increase • Fuel injectors or fuel valve will supply the fuel oil in fine spray when the piston is nearly at top dead centre
• The fuel will then be mixed with air (compressed) and burn inside the cylinder when the piston is at TDC. • The expanding gases on top of the piston (completed combustion) will push the piston moving it downward and rotating the crankshaft . • The cycle will be repeated until the engine stops
Cycle of Operations • Four strokes of CI engine are as follows:- – Suction Stroke / Induction Stroke – Compression Stroke – Explosion Stroke / Power Stroke – Exhaust Stroke
SUCTION STROKE • In which the air is admitted to the engine cylinder
COMPRESSION STROKE • In which the charge of fresh air is compressed by the piston, and fuel is injected just before the point of maximum compression
POWER STROKE • In which the air- fuel mixture is ignited by the heat produced by compression of air • The pressure rises due to fuel combustion and pushes piston downwards to drive the engine
EXHAUST STROKE • Exhaust valve opens at the end of power stroke • The expanded burnt gases are exhausted / expelled from the cylinder
• The four strokes in duel cycle of CI engine are completed in two revolutions of the crankshaft. • There are thus two piston strokes in each revolution of the crankshaft
FOUR STROKE ENGINE INLET VALVE CYLINDER HEAD FUEL INJECTOR EXHAUST VALVE PISTON CYLINDER LINER CRANKSHAFT DIRECTION CRANK PIN INDUCTION STROKE / COMPRESSION STROKE POWER / EXPANSION STROKE EXHAUST STROKE STROKE EXHAUST SCAVENGE STROKE
How strokes are executed • Strokes are executed by combination of valves and gears
SUCTION / INDUCTION STROKE • Piston draws air into cylinder during downward movement or stroke through opened inlet valve. (suction effect) • Exhaust valve and fuel injector are closed • At the end of the stroke (BDC) the inlet valve close, which inside the cylinder now full with fresh air.
COMPRESSION STROKE • Stroke begins when the piston starts to move upward (from BDC to TDC). • Inlet valve, exhaust valve and fuel injector remain closed. • The air which is trapped in the cylinder is now compressed rising in temperature
POWER STROKE • Before the piston reaches TDC(approx.15 – 20o), the fuel injectors supply fuel oil in a fine spray(end approx. 15-20o after TDC) • The mixture (fuel oil and air) ignites and explodes while the piston crosses TDC • High pressure (expansion of the gases) on top of the piston push the piston downward towards BDC
EXHAUST STROKE • Stroke begins when the piston again starts to move upward (from BDC to TDC) as in compression stroke, however only exhaust valves are opened. • The exhaust gases are expelled from the cylinder through the exhaust valve ports. • At the end of the stroke (TDC), the exhaust valve closes but inlet valve is opened starting the cycle once again
Power produced • Power produced by a 4-stroke cycle engine in kW is given as PLAN Power = 2 P= Mean effective pressure, kN/m2 L= Stroke length, m A= Area of cylinder bore, m2 N= Revolution/second
4 - STROKE CYCLE 9 PISTON POSITION 8 3 4 10 9 5 3 4 5 8 10 2 6 1 2 6 DIRECTION 7 PRESSURE 1 1/7
4 - STROKE CYCLE • 1-2 Suction stroke ends • 2-3 Compression stroke. Inlet valve closed and piston moved upwards to compress the trapped air (Temperature rises). • 3-4-5 Fuel injector in operation. Combustion occurs (mixture of compressed air and fuel) • 5-6 Due to expansion of gases piston moves downward. (Power stroke) • 6-7-8 Exhaust stroke. Exhaust valve opens and piston moves upward removing gases. • 8-9-10 Overlapping period: both exhaust and inlet valves are open. • 10-1 Suction stroke – piston moves downward. Exhaust valve closed and inlet valve open. • 1- the rest – The cycle continues until the engine stops
Exh. v/v closes Fuel Fuel injection injection begins ends PO COMPRESSION STROKE W E ER T STROK Inlet v/v ST opens RO SUC KE Rotation EXHAUS TIO N STR Inlet v/v OKE closes Exh. v/v opens FOUR STROKE TIMING DIAGRAM
VALVE OVERLAPPING It can be defined as the period when inlet and exhaust valve were open at the same time. E.g., • Inlet valve opened before the piston reached TDC at the end of exhaust stroke, say 20o before TDC. • Exhaust valve remained open and will be closed at certain degree of the piston movement after TDC, say 20o after TDC. • By providing overlapping period on 4 – stroke engine, the residual exhaust gases will be expelled effectively with the rushing in of fresh air.
VALVE OVERLAP TDC OVERLAPPING PERIOD Inlet v/v Exh. v/v opens closes
2-Stroke cycle diesel engines
• Learning Objective: Know the basic cycle and design features of modern marine diesel engines Specific Objectives: • Describe the operation cycle process of a 2-stroke diesel engine. • Identify the 2-stroke engine timing diagram
TWO STROKE CYCLE • The two stroke cycle is so called because it takes two strokes of the piston or one revolution of crank shaft to complete the processes needed to convert the energy in the fuel into work.
Why 2-Stroke Cycle Engines • We know 4-stroke cycle engine gives only one power stroke out of 4 strokes of the piston or one power stroke in two revolutions of the crank shaft. • This makes engine’s power to weight ratio low mainly because three strokes consume power against one which produces
2S • In the two stroke engine, cycle is completed in two strokes of the piston or one revolution of the crankshaft. • Thus out of 3 power consuming strokes of the 4- stroke cycle two strokes are saved • Engine thus produces one power stroke in every revolution of the engine which is two times in comparison to 4-stroke cycle • This improves power to weight ratio of the engine and reduces its size for same power.
2S • 2-Stroke cycle is achieved by eliminating suction and exhaust strokes of the 4-stroke cycle • In order to eliminate suction and exhaust strokes, some special arrangements are required to be provided for:- -.charging air into cylinder without suction from piston - Exhaust gases must be expelled out of the cylinder without assistance from piston
Power Piston Comp stroke stroke Exst port Exst port Inlet air Piston Inlet air port port
The crankshaft is revolving clockwise and the piston is moving up the cylinder, compressing the charge of air. Because energy is being transferred into the air, pressure and temperature increase. By the time the piston is near the top of the cylinder (known as Top Dead Center or TDC) the pressure is >100 bar and the temperature > 500°C
Just before TDC fuel is injected into the cylinder by the fuel injector. The fuel is "atomised" into tiny droplets. Being very small, these droplets heat up very quickly and start to burn as the piston passes over TDC. The expanding gas from the fuel burning in the oxygen forces the piston down the cylinder, turning the crankshaft. It is during this stroke that work energy is being put into the engine; during the upward stroke of the piston, the engine is having
As the piston moves down the cylinder, the useful energy from the burning fuel is expended. At about 110° after TDC the exhaust valve opens and the hot exhaust gas (consisting mostly of nitrogen, carbon dioxide, water vapour and unused oxygen) begin to leave the cylinder.
At about 140º after TDC the piston uncovers a set of ports known as scavenge ports. Pressurized air enters the cylinder via these ports and pushes the remaining exhaust gas from the cylinder, "scavenging". The piston now goes past BDC and starts moving up the cylinder, closing the scavenge ports. The exhaust valve then closes and compression begins.
The two stroke cycle can also be illustrated on a timing diagram. 1 -2 Compression 2 - 3 Fuel Injection 3 - 4 Power 4 - 5 Exhaust Blowdown 5 - 6 Scavenging 6 - 1 Post Scavenging 1. approx 110º BTDC 2. approx 10º BTDC 3. approx 12º ATDC 4. approx 110º ATDC 5. approx 140º ATDC 6. approx 140º BTDC
4 5 5 6 4 PISTON POSITION 6 7 3 7 3 2 8 8 2 1 1 PRESSURE
• 1-2 Scavenging period, both exhaust and inlet ports are open. • 2-3 Scavenge stroke ends. Exhaust ports remain open to ensure only fresh air remains in the cylinder. • 3-4 Compression takes place. Both ports closed. The air is then compressed by the upward movement of the piston. • 4-5-6 Fuel injector is operational supplying fuel oil. • 6-7 Due to expansion of gases, piston moves downward. (Power stroke) • 7-8 When piston crown/top ring passes the exhaust ports, exhaust begins • 8-1 When the piston passes the inlet ports, Scavenging begins and fresh air fills the cylinder, thus pushing the remaining exhaust gases out
Fuel Fuel injection injection begins ends ON POW SI ES ER R MP STR CO OK Rotation E Scavenge Scavenge ports ports close open Exhaust Exhaust SCAVENGE ports ports close open EXHAUST TWO STROKE TIMING DIAGRAM
The 2 stroke crosshead engine works on exactly the same principle and cycle as the 2 stroke trunk piston engine.
The disadvantages of the two stroke trunk piston engine are that: It has a low overall height, lubricating oil splashed up from the crankcase to lubricate the liner can find its way into the scavenge space, causing fouling and a risk of fire. There is also the likelihood of liner and piston skirt wear, allowing air into the crankcase. This can supply the required oxygen for an explosion should a hot spot develop. The crankcase oil must have additives which can cope with contamination from products of combustion, and the acids formed during combustion due to the sulphur in the fuel.
The majority of 2 stroke engines encountered at sea are of the "crosshead" type. In this type of engine the combustion space (formed by the cylinder liner, piston and cylinder head), and the scavenge space are separated from the crankcase by the diaphragm plate. The piston rod is bolted to the piston and passes through a stuffing box mounted in the diaphragm plate. The stuffing box provides a seal between the two spaces, stopping oil from being carried up to the scavenge space, and scavenge air leaking into the crankcase. The foot of the piston rod is bolted to the crosshead pin. The top end of the connecting rod swings about the crosshead pin, as the downward load from the expanding gas applies a turning force to the crankshaft. To ensure that the crosshead reciprocates in alignment with the piston in the cylinder, guide shoes are attached either side of the crosshead pin. These shoes are lined with white metal, a bearing material and they reciprocate against the crosshead guides, which are bolted to the frame of the engine. The crosshead guides are located in-between each cylinder. Using the crosshead design of engine allows engines to be built with very long strokes - which means the engine can burn a greater quantity of fuel/stroke and develop more power. The fuel used can be of a lower grade than that used in a trunk piston engine, with a higher sulphur content, whilst high alkalinity cylinder oils with a different specification to that of the crankcase oil are used to lubricate the cylinder liner and piston rings and combat the effects of acid attack.
SCAVENGING • To ensure a sufficient supply of fresh air for combustion by removing all remaining exhaust gases by blowing with these fresh air. • Supercharging is a large mass of air that is supplied to the cylinder by blowing it in under pressure either by electrically driven auxiliary blower or exhaust gas driven turbocharger. • The flow path of the scavenge air is decided by the engine port shape and design and the exhaust arrangements.
SCAVENGING PERIOD It can be defined as a period when inlet and exhaust are open at the same time: • Remaining exhaust gas will be expelled from the cylinder through exhaust ports or exhaust valve (if fitted). • Fresh air which has collected in the scavenge manifold rush into the cylinder • Scavenging period: Normally when piston is at BDC, (or as per maker or engine design or the location of the ports itself)
SCAVENGING METHODS • CROSS/DIRECT – FLOW SCAVENGING • LOOP SCAVENGING • UNIFLOW SCAVENGING
Cross/direct flow scavenging Exhaust manifold Scavenge manifold
Loop scavenging Exhaust manifold Scavenge manifold
2 stroke engines do not have exhaust valves; With scavenge ports in the cylinder liner, they are fitted with exhaust ports located just above the scavenge ports. As the piston uncovers the exhaust ports on the power stroke, the exhaust gas starts to leave the cylinder. When the scavenge ports are uncovered, scavenge air loops around the cylinder and pushes the remaining exhaust gas out of the cylinder. This type of engine is known as a loop scavenged engine. Note that the piston skirt is much longer than that for a uniflow scavenged engine. This is because the skirt has to seal the scavenge and exhaust ports when the piston is at TDC.
TWO STROKE ADVANTAGES • Compactness in relation to the power output. Not required to increase brake mean effective pressure or the engine speed to increase rating. (High bmep increases the stresses on engine components, greater rate of cylinder wear, whilst the alternative of higher speed, valve flutter may become a serious problem) • Each out-stroke being a working stroke gives more even turning for the same number of cranks, consequently a lighter flywheel may be employed. • The reversing operation of rotation is simplified since there is less valve gear to contend with.
OTHER ADVANTAGES • Fewer moving parts and lower maintenance • Lower specific fuel consumption • No gear loss • Simplicity in construction • Longer life time • Higher reliability (product) • Low lubricating oil consumption • Better ability to burn low quality fuel oil
FOUR STROKE ADVANTAGES • Good volumetric efficiency, good combustion characteristic and positive exhaust scavenging. • The thermal and mechanical efficiencies are slightly better than 2S engine. • Only half the quantity of the heat generated in the cylinders has to be dealt within a given time, so that efficient lubrication of the piston and cooling of the cylinder is more easily accomplished.
OTHER ADVANTAGES • Lower initial cost for equivalent power • Ease of installation • Lower weight per unit power • Saving in weight and engine room length • Increased cargo capacity • Free choice of propeller speed through gearing • Suitable for electrical power take off
Supercharging/Turbocharging • Process of pushing a higher pressure air charge into the cylinder greater than atmospheric pressure, so that extra mass of air can be delivered into cylinder to burn more fuel and produce extra power. • Turbocharging can increase power output of engine by 60%
Turbocharging • Very effective pressure charging. • Utilizes 20% of waste heat in exhaust gas which contains 35% of fuel heat. • How?
•By increasing mass of air in cylinder, more fuel can be burned and correspondingly power output will be increased •Various methods can be adopted: –Electrically powered auxiliary blower –Utilization of heat energy from exhaust gas to drive a single stage impulse turbine directly coupled to a simple blower (free running unit) called exhaust gas turbocharger Turbocharger utilizes free energy of exhaust gases and hence improves efficiency of the engine
Typical heat balance of an engine Useful Output (Brake Power) 34% Cooling Loss 30% Exhaust Loss 26% Friction, Radiation, etc. 10% ------- Total Heat Input 100%
Turbocharger System
Advantages • Increased power for an engine of the same size OR reduction in size for an engine with the same power output. • Reduced specific fuel oil consumption -> mechanical, thermal and scavenge efficiencies are improved due to less cylinders, greater air supply and use of exhaust gasses. • Thermal loading is reduced due to shorter more efficient burning period for the fuel leading to less exacting cylinder conditions.
Risk • Crankcase explosion • Scavenge fire
Design consideration • Types of fuel and fuel oil system design • Types of lubricating oil and lubricating oil systems • Cooling systems • Waste heat utilization systems • Intake and exhaust valve systems • Starting air systems • Instrumentation system • Control and automation system • Installation items • Safety features
Summary • Principle of ICE • Theoretical Cycles • Basic principle of operations of working cycle • Cycle & Timing Diagram • Principles of Scavenging & Arrangements • Advantages of 2S & 4S • Structural differences • Overlap of Inlet & Exhaust
References • Introduction to Marine Engineering, • Marine Engineering , Roy L. Harrington, SNAME, 198 • El-Hawary, F. (2001). Ocean Engineering Handbook. CRC Press, UK. • Calder, Nigel (2007): Marine diesel engine: maintenance, troubleshooting and repair.

More Related Content

PPTX
DJA3032 CHAPTER 5
bymechanical86
 
PPTX
DJA3032 CHAPTER 7
bymechanical86
 
PPTX
DJA3032 CHAPTER 1
bymechanical86
 
PPT
Performance parameters
byPeeyush Firodiya
 
PPT
Dynamometers by abhil ash
byabhilash k
 
PDF
Automotive Systems course (Module 08) - Starting Systems for road vehicles
byMário Alves
 
PPTX
Piston presentation
byTejinderpal Singh
 
PPTX
Rolling Contact Bearing theory Prof. Sagar Dhotare
bySagar Dhotare
 
DJA3032 CHAPTER 5
bymechanical86
 
DJA3032 CHAPTER 7
bymechanical86
 
DJA3032 CHAPTER 1
bymechanical86
 
Performance parameters
byPeeyush Firodiya
 
Dynamometers by abhil ash
byabhilash k
 
Automotive Systems course (Module 08) - Starting Systems for road vehicles
byMário Alves
 
Piston presentation
byTejinderpal Singh
 
Rolling Contact Bearing theory Prof. Sagar Dhotare
bySagar Dhotare
 

What's hot

PPT
Engine systems diesel engine analyst - full
byServicio Integral Diesel SAC
 
PPTX
UNIT-I_Introduction to Turbomachines.pptx
byparesh sawai
 
PPTX
DJA3032 CHAPTER 2
bymechanical86
 
PPTX
Piston engine construction
bybecharahajj123
 
PDF
ENGINE PRESENTATION
byShahmeer Baweja
 
PDF
Fuel Injection Systems Diesel
byAyb Mechatronics
 
PPTX
Performance testing of IC engine
byINDRAKUMAR PADWANI
 
PDF
valve timing diagram of two stroke & four stroke engine
bySujit Kumar Chaurasia
 
PDF
Performance of ic engine
byHardik Siddhpura
 
PPTX
Fundamentals of jet propulsion ppt
byC BALA MURUGAN
 
PPT
Automatic Transmission
byNizam Anuar
 
PPTX
1 accumulators and intensifiers
byDr.R. SELVAM
 
PPTX
Rolling bearing
byPOORNIMA COLLEGE OF ENGINEERING, JAIPUR
 
PPTX
Condition monitoring of rotary machines
byAshish Singh
 
PPTX
IC engine ppt
bykapilvadiyar
 
PPTX
Piston Design & Analysis ppt
byAbdul Awal (Maahi)
 
PDF
Common rail diesel fuel systems
byamged radhi
 
PPT
BATTERY SYSTEM IN AUTOMOBILE.ppt
byabhijitbiswas687965
 
PPTX
DJA3032 CHAPTER 4
bymechanical86
 
PPTX
PPT of Antifriction bearings.pptx
byTejasHN2
 
Engine systems diesel engine analyst - full
byServicio Integral Diesel SAC
 
UNIT-I_Introduction to Turbomachines.pptx
byparesh sawai
 
DJA3032 CHAPTER 2
bymechanical86
 
Piston engine construction
bybecharahajj123
 
ENGINE PRESENTATION
byShahmeer Baweja
 
Fuel Injection Systems Diesel
byAyb Mechatronics
 
Performance testing of IC engine
byINDRAKUMAR PADWANI
 
valve timing diagram of two stroke & four stroke engine
bySujit Kumar Chaurasia
 
Performance of ic engine
byHardik Siddhpura
 
Fundamentals of jet propulsion ppt
byC BALA MURUGAN
 
Automatic Transmission
byNizam Anuar
 
1 accumulators and intensifiers
byDr.R. SELVAM
 
Rolling bearing
byPOORNIMA COLLEGE OF ENGINEERING, JAIPUR
 
Condition monitoring of rotary machines
byAshish Singh
 
IC engine ppt
bykapilvadiyar
 
Piston Design & Analysis ppt
byAbdul Awal (Maahi)
 
Common rail diesel fuel systems
byamged radhi
 
BATTERY SYSTEM IN AUTOMOBILE.ppt
byabhijitbiswas687965
 
DJA3032 CHAPTER 4
bymechanical86
 
PPT of Antifriction bearings.pptx
byTejasHN2
 

Viewers also liked

PPTX
Four stroke 3 RANA SAIFULLAH KHAN
byRana Saif Khan
 
PPT
FOUR STROKE ENGINE
byshaffu786
 
PPTX
4-stroke Diesel Engine
byMridul Rawat
 
PDF
New Strategies for Financing Agricultural Mechanization
byTechnical Centre for Agricultural and Rural Cooperation ACP-EU (CTA)
 
PPTX
Particle behavior, solid, liquid gas (Teach)
byMoira Whitehouse
 
PPT
Icengine
byRaj Vyas
 
PPT
As introduction ic engine
bysharmaabhi
 
PPTX
Piston Engines: Ignition
byJess Peters
 
PDF
Thermodynamics
byEdward Blurock
 
PDF
05 part2 steady flow analysis of reacting mixtures
bygunabalan sellan
 
PPTX
MET 401 Chapter 3 fuels_and_combustion
byIbrahim AboKhalil
 
PDF
CI Engine Emission
byRajat Seth
 
PPT
Emission control system
byNizam Anuar
 
PPT
Lubrication Reliability by Lubretec : a 10 step approach to World Class Maint...
byToon Van Grunderbeeck
 
PPTX
PPT ON GREEN CONCRETE BY TANMAY KUMAR
byTanmay Kumar
 
PPTX
2 stroke & 4 stroke engine
byHarshal Shah
 
PPTX
ppt on 2 stroke and 4 stroke petrol engine
byharshid panchal
 
PPT
IC Engine PPt
byRocker ʌvinʌsh
 
PDF
Basic Mechanical Engineering - IC engines
bySteve M S
 
PPTX
INTERNAL COMBUSTION ENGINES PPT
byAKASH1001
 
Four stroke 3 RANA SAIFULLAH KHAN
byRana Saif Khan
 
FOUR STROKE ENGINE
byshaffu786
 
4-stroke Diesel Engine
byMridul Rawat
 
New Strategies for Financing Agricultural Mechanization
byTechnical Centre for Agricultural and Rural Cooperation ACP-EU (CTA)
 
Particle behavior, solid, liquid gas (Teach)
byMoira Whitehouse
 
Icengine
byRaj Vyas
 
As introduction ic engine
bysharmaabhi
 
Piston Engines: Ignition
byJess Peters
 
Thermodynamics
byEdward Blurock
 
05 part2 steady flow analysis of reacting mixtures
bygunabalan sellan
 
MET 401 Chapter 3 fuels_and_combustion
byIbrahim AboKhalil
 
CI Engine Emission
byRajat Seth
 
Emission control system
byNizam Anuar
 
Lubrication Reliability by Lubretec : a 10 step approach to World Class Maint...
byToon Van Grunderbeeck
 
PPT ON GREEN CONCRETE BY TANMAY KUMAR
byTanmay Kumar
 
2 stroke & 4 stroke engine
byHarshal Shah
 
ppt on 2 stroke and 4 stroke petrol engine
byharshid panchal
 
IC Engine PPt
byRocker ʌvinʌsh
 
Basic Mechanical Engineering - IC engines
bySteve M S
 
INTERNAL COMBUSTION ENGINES PPT
byAKASH1001
 

Similar to 24514675 2-internal-combustion-engine

PDF
LIM Technology - Scdi engine - fuel efficient engine
bylimtechnology
 
PDF
THERMAL_ENGG_Module_2_STUDY_MATERIAL_f31f24bf2a214020795dc836391208de.pdf
bymomentr50
 
PDF
Reciprocating Internal Combustion Engine
byMushtaqAhmedSulaiman
 
PPT
Gas turbine course
byAmitabh Gairola [LION] amitaban1990@gmail.com
 
PPTX
engine
byEzhil Arasu
 
PDF
I c engines a study
byNoT yeT woRkiNg !! iM stiLl stUdYinG !!hehe, im still youth
 
PDF
010
byphysics101
 
PPTX
Unit 1 Internal combustion engine a part of applied thermodynamics
byChitrakantDewangan2
 
PPTX
Air Std Cycles.pptx
bydigitaladh
 
PDF
Combustion
bysolomonteklemichael
 
PPTX
Air ^0 Fuel Ind 2k21 Part-3 Raw 6 Nov 24.pptx
byMuhammadAbdullahmali4
 
PPTX
Combustion cycle
byHaMi ÇhâüDärý
 
PPTX
Basic Mech Engineering- Internal Combustion engines
byMahesCb1
 
DOCX
Mechanical Technology Assignment_210061102.docx
byAbdullahKafi18
 
PDF
Basics of IC engine
bySLA1987
 
PDF
Thermodynamicsbycengelandyunuscimbalpladean
byDavid850003
 
DOCX
Variable Volume Engine Report
byHimanshu Verma
 
PDF
Chapter 1 internal combustion engine
byMuhd Taufik Muhammad
 
PPT
Chapter 18
bymcfalltj
 
PPTX
Four stroke engines and Two stroke engines
bybhavika chavda
 
LIM Technology - Scdi engine - fuel efficient engine
bylimtechnology
 
THERMAL_ENGG_Module_2_STUDY_MATERIAL_f31f24bf2a214020795dc836391208de.pdf
bymomentr50
 
Reciprocating Internal Combustion Engine
byMushtaqAhmedSulaiman
 
Gas turbine course
byAmitabh Gairola [LION] amitaban1990@gmail.com
 
engine
byEzhil Arasu
 
I c engines a study
byNoT yeT woRkiNg !! iM stiLl stUdYinG !!hehe, im still youth
 
010
byphysics101
 
Unit 1 Internal combustion engine a part of applied thermodynamics
byChitrakantDewangan2
 
Air Std Cycles.pptx
bydigitaladh
 
Combustion
bysolomonteklemichael
 
Air ^0 Fuel Ind 2k21 Part-3 Raw 6 Nov 24.pptx
byMuhammadAbdullahmali4
 
Combustion cycle
byHaMi ÇhâüDärý
 
Basic Mech Engineering- Internal Combustion engines
byMahesCb1
 
Mechanical Technology Assignment_210061102.docx
byAbdullahKafi18
 
Basics of IC engine
bySLA1987
 
Thermodynamicsbycengelandyunuscimbalpladean
byDavid850003
 
Variable Volume Engine Report
byHimanshu Verma
 
Chapter 1 internal combustion engine
byMuhd Taufik Muhammad
 
Chapter 18
bymcfalltj
 
Four stroke engines and Two stroke engines
bybhavika chavda
 

Recently uploaded

PDF
What Is a Private LLM and Why Enterprises Need It
byAivada
 
PDF
Day 5 - Red Team + Blue Team in the Cloud - 2nd Sight Lab Cloud Security Class
by2nd Sight Lab
 
PDF
Six Shifts For 2026 (And The Next Six Years)
byDavid Armano
 
DOCX
iRobot Post‑Mortem and Alternative Paths - Discussion Document for Boards and...
byDave Litwiller
 
PPTX
wob-report.pptxwob-report.pptxwob-report.pptx
byssuser0d171c
 
PDF
Cross-Cultural Agile Development -Challenges and Strategies for Overcoming Them-
byTakashi Makino
 
PDF
100 Insights After the 200th Issue of NewMind AI Journal
byNewMind AI
 
PPTX
Emancipatory Information Retrieval: Radically Reorienting Information Retriev...
byBhaskar Mitra
 
PDF
Lab 1.5 - Sharing Secrets with GPG ~ 2nd Sight Lab Cloud Security Class
by2nd Sight Lab
 
PDF
Unlocking the Power of Salesforce Architecture: Frameworks for Effective Solu...
byvarsha30tiwari
 
PDF
10 Things AI-First Apps Do Differently by iProgrammer Solutions
byiProgrammer Solutions Private Limited
 
PPTX
Building Agents in Microsoft Agent Framework.pptx
byUdaiappa Ramachandran
 
PPTX
DYNAMICALLY.pptx good for the teachers or students to do seminars and for tea...
bympoorvika031
 
PPTX
Gemini vs ChatGPT : Comparing Top AI Models
byDigicarrom
 
PPTX
Top _HR Technology Trends _for 2026_.pptx
byAutomationEdge Technologies
 
PDF
HCSP-Presales-Campus Network Planning and Design V2.0
byVeronica916344
 
PDF
DevFest El Jadida 2025 - Product Thinking
byElmehdi AMLOU
 
PDF
Workshop on Sustaining & Growing Open Source Communities - GAS2025
bySammy Fung
 
PDF
Security Forum Sessions from Houston 2025 Event
byMark Simos
 
PDF
How to Evaluate a High Performance Database
byScyllaDB
 
What Is a Private LLM and Why Enterprises Need It
byAivada
 
Day 5 - Red Team + Blue Team in the Cloud - 2nd Sight Lab Cloud Security Class
by2nd Sight Lab
 
Six Shifts For 2026 (And The Next Six Years)
byDavid Armano
 
iRobot Post‑Mortem and Alternative Paths - Discussion Document for Boards and...
byDave Litwiller
 
wob-report.pptxwob-report.pptxwob-report.pptx
byssuser0d171c
 
Cross-Cultural Agile Development -Challenges and Strategies for Overcoming Them-
byTakashi Makino
 
100 Insights After the 200th Issue of NewMind AI Journal
byNewMind AI
 
Emancipatory Information Retrieval: Radically Reorienting Information Retriev...
byBhaskar Mitra
 
Lab 1.5 - Sharing Secrets with GPG ~ 2nd Sight Lab Cloud Security Class
by2nd Sight Lab
 
Unlocking the Power of Salesforce Architecture: Frameworks for Effective Solu...
byvarsha30tiwari
 
10 Things AI-First Apps Do Differently by iProgrammer Solutions
byiProgrammer Solutions Private Limited
 
Building Agents in Microsoft Agent Framework.pptx
byUdaiappa Ramachandran
 
DYNAMICALLY.pptx good for the teachers or students to do seminars and for tea...
bympoorvika031
 
Gemini vs ChatGPT : Comparing Top AI Models
byDigicarrom
 
Top _HR Technology Trends _for 2026_.pptx
byAutomationEdge Technologies
 
HCSP-Presales-Campus Network Planning and Design V2.0
byVeronica916344
 
DevFest El Jadida 2025 - Product Thinking
byElmehdi AMLOU
 
Workshop on Sustaining & Growing Open Source Communities - GAS2025
bySammy Fung
 
Security Forum Sessions from Houston 2025 Event
byMark Simos
 
How to Evaluate a High Performance Database
byScyllaDB
 

24514675 2-internal-combustion-engine

  • 1.
  • 2.
  • 3.
  • 4.
    • Course LearningObjective: Familiarize students to the basic cycle and design features of modern marine diesel engines Specific Objectives: - Define the theory and principle of Internal Combustion Engine - Describe basic operations of working cycle - Identify the engine timing diagram - Describe differences and advantages of 2S & 4S
  • 5.
    Principle of I.C.E •An internal combustion engine is one in which the fuel is burnt within the engine -> usually of the reciprocating type. • It involve system where combustion of the fuel and the conversion of the heat energy from combustion to mechanical energy takes place within the cylinders (ICE)
  • 6.
    I.C.E. CATEGORIES – Sparkignition engines use gaseous or volatile distillate fuels -> work on a modified Otto cycle -> operate on the 2 or 4 – stroke cycle. – Compression ignition engine use distillate liquid fuels -> work on either 2 or 4 – stroke cycle and normally designed to operate on the dual-combustion cycle (Otto and Diesel cycle)
  • 7.
    Otto cycle • Inthe Otto cycle the theoretical pressure – volume diagram is formed from : two constant – volume and two adiabatic processes. • The air in the cylinder is compressed adiabatically. • Heat is added to the air at constant volume -> Work is done during the adiabatic expansion and -> then heat is rejected at constant volume
  • 8.
    Otto Cycle Pressure (Pa) C P2 D P1 B A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant volume (combustion) C–D : Adiabatic expansion D–A : Heat rejected at constant volume (exhaust)
  • 9.
    Otto Cycle • 1.The induction stroke takes place at A.  Although in theory the pressure should be the same as atmospheric, in practice it's rather lower.  The amount of petrol air mixture taken in can be increased by use of a supercharger. • 2. A to B is the compression stroke.  Both valves are closed.  The compression is adiabatic, and no heat enters or leaves the cylinder.  • 3. Ignition occurs at C.  The gases resulting from the ignition expand adiabatically, leading to the power stroke. • 4. D to A the gas is cooled instantaneously.   • 5. At A the exhaust stroke occurs and the the gases are removed at constant pressure to the atmosphere. • 6. Strange as it may seem, the piston does half a revolution at A.  Actually it's slightly in practice, as the the valve timing is more complex.
  • 10.
    Diesel cycle • Inthe diesel cycle the theoretical pressure- volume diagram is formed from two adiabatic operations, one constant-pressure and one constant-volume operation. • Air is compressed adiabatically, then heat is added at constant pressure. Adiabatic expansion takes place and then heat is rejected at constant volume
  • 11.
    Diesel Cycle Pressure (Pa) B C P D A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant pressure (combustion) C–D : Adiabatic expansion D–A : Heat rejected at constant volume
  • 12.
    Diesel cycle • 1.The induction stroke takes air in ideally at constant volume, pressure at temperature. • 2. The compression stroke takes place from A to B.  The air is compressed adiabatically to about 1/20 of its original volume.  It gets hot. • 3. From B to C fuel is injected in atomised form.  It burns steadily so that the pressure on the piston is constant. • 4. From C to D the power stroke moves the piston down as adiabatic expansion takes place. • 5. D to A cooling and exhaust occurs.
  • 13.
    Dual cycle • Inthe dual cycle, air is compressed adiabatically, then heat is added, partly in a constant volume process and the remainder in a constant pressure process. • Expansion takes place adiabatically and then heat is rejected at constant volume
  • 14.
    Pressure (Pa) C D P E B A V1 V2 Volume (m3) A–B : Adiabatic compression B–C : Heat received at constant volume C–D : Heat received at constant pressure D–E : Adiabatic expansion E–A : Heat rejected at constant volume
  • 15.
    COMPRESSION IGNITION ENGINE • Compression ignition engine works on dual cycle • The fresh air enters each of the engine cylinders and is compressed by the upward movement of the piston. • The compression causes the temperature and pressure of the fresh air to increase • Fuel injectors or fuel valve will supply the fuel oil in fine spray when the piston is nearly at top dead centre
  • 16.
    • The fuelwill then be mixed with air (compressed) and burn inside the cylinder when the piston is at TDC. • The expanding gases on top of the piston (completed combustion) will push the piston moving it downward and rotating the crankshaft . • The cycle will be repeated until the engine stops
  • 17.
    Cycle of Operations •Four strokes of CI engine are as follows:- – Suction Stroke / Induction Stroke – Compression Stroke – Explosion Stroke / Power Stroke – Exhaust Stroke
  • 18.
    SUCTION STROKE • Inwhich the air is admitted to the engine cylinder
  • 19.
    COMPRESSION STROKE • Inwhich the charge of fresh air is compressed by the piston, and fuel is injected just before the point of maximum compression
  • 20.
    POWER STROKE • Inwhich the air- fuel mixture is ignited by the heat produced by compression of air • The pressure rises due to fuel combustion and pushes piston downwards to drive the engine
  • 21.
    EXHAUST STROKE • Exhaustvalve opens at the end of power stroke • The expanded burnt gases are exhausted / expelled from the cylinder
  • 22.
    • The fourstrokes in duel cycle of CI engine are completed in two revolutions of the crankshaft. • There are thus two piston strokes in each revolution of the crankshaft
  • 23.
    FOUR STROKE ENGINE INLETVALVE CYLINDER HEAD FUEL INJECTOR EXHAUST VALVE PISTON CYLINDER LINER CRANKSHAFT DIRECTION CRANK PIN INDUCTION STROKE / COMPRESSION STROKE POWER / EXPANSION STROKE EXHAUST STROKE STROKE EXHAUST SCAVENGE STROKE
  • 24.
    How strokes areexecuted • Strokes are executed by combination of valves and gears
  • 26.
    SUCTION / INDUCTIONSTROKE • Piston draws air into cylinder during downward movement or stroke through opened inlet valve. (suction effect) • Exhaust valve and fuel injector are closed • At the end of the stroke (BDC) the inlet valve close, which inside the cylinder now full with fresh air.
  • 27.
    COMPRESSION STROKE • Strokebegins when the piston starts to move upward (from BDC to TDC). • Inlet valve, exhaust valve and fuel injector remain closed. • The air which is trapped in the cylinder is now compressed rising in temperature
  • 28.
    POWER STROKE • Before the piston reaches TDC(approx.15 – 20o), the fuel injectors supply fuel oil in a fine spray(end approx. 15-20o after TDC) • The mixture (fuel oil and air) ignites and explodes while the piston crosses TDC • High pressure (expansion of the gases) on top of the piston push the piston downward towards BDC
  • 29.
    EXHAUST STROKE • Stroke begins when the piston again starts to move upward (from BDC to TDC) as in compression stroke, however only exhaust valves are opened. • The exhaust gases are expelled from the cylinder through the exhaust valve ports. • At the end of the stroke (TDC), the exhaust valve closes but inlet valve is opened starting the cycle once again
  • 30.
    Power produced • Powerproduced by a 4-stroke cycle engine in kW is given as PLAN Power = 2 P= Mean effective pressure, kN/m2 L= Stroke length, m A= Area of cylinder bore, m2 N= Revolution/second
  • 31.
    4 - STROKECYCLE 9 PISTON POSITION 8 3 4 10 9 5 3 4 5 8 10 2 6 1 2 6 DIRECTION 7 PRESSURE 1 1/7
  • 32.
    4 - STROKECYCLE • 1-2 Suction stroke ends • 2-3 Compression stroke. Inlet valve closed and piston moved upwards to compress the trapped air (Temperature rises). • 3-4-5 Fuel injector in operation. Combustion occurs (mixture of compressed air and fuel) • 5-6 Due to expansion of gases piston moves downward. (Power stroke) • 6-7-8 Exhaust stroke. Exhaust valve opens and piston moves upward removing gases. • 8-9-10 Overlapping period: both exhaust and inlet valves are open. • 10-1 Suction stroke – piston moves downward. Exhaust valve closed and inlet valve open. • 1- the rest – The cycle continues until the engine stops
  • 33.
    Exh. v/v closes Fuel Fuel injection injection begins ends PO COMPRESSION STROKE W E ER T STROK Inlet v/v ST opens RO SUC KE Rotation EXHAUS TIO N STR Inlet v/v OKE closes Exh. v/v opens FOUR STROKE TIMING DIAGRAM
  • 34.
    VALVE OVERLAPPING It canbe defined as the period when inlet and exhaust valve were open at the same time. E.g., • Inlet valve opened before the piston reached TDC at the end of exhaust stroke, say 20o before TDC. • Exhaust valve remained open and will be closed at certain degree of the piston movement after TDC, say 20o after TDC. • By providing overlapping period on 4 – stroke engine, the residual exhaust gases will be expelled effectively with the rushing in of fresh air.
  • 35.
    VALVE OVERLAP TDC OVERLAPPING PERIOD Inlet v/v Exh. v/v opens closes
  • 36.
  • 37.
    • Learning Objective:Know the basic cycle and design features of modern marine diesel engines Specific Objectives: • Describe the operation cycle process of a 2-stroke diesel engine. • Identify the 2-stroke engine timing diagram
  • 38.
    TWO STROKE CYCLE •The two stroke cycle is so called because it takes two strokes of the piston or one revolution of crank shaft to complete the processes needed to convert the energy in the fuel into work.
  • 39.
    Why 2-Stroke CycleEngines • We know 4-stroke cycle engine gives only one power stroke out of 4 strokes of the piston or one power stroke in two revolutions of the crank shaft. • This makes engine’s power to weight ratio low mainly because three strokes consume power against one which produces
  • 40.
    2S • In thetwo stroke engine, cycle is completed in two strokes of the piston or one revolution of the crankshaft. • Thus out of 3 power consuming strokes of the 4- stroke cycle two strokes are saved • Engine thus produces one power stroke in every revolution of the engine which is two times in comparison to 4-stroke cycle • This improves power to weight ratio of the engine and reduces its size for same power.
  • 41.
    2S • 2-Stroke cycleis achieved by eliminating suction and exhaust strokes of the 4-stroke cycle • In order to eliminate suction and exhaust strokes, some special arrangements are required to be provided for:- -.charging air into cylinder without suction from piston - Exhaust gases must be expelled out of the cylinder without assistance from piston
  • 42.
    Power Piston Comp stroke stroke Exst port Exst port Inlet air Piston Inlet air port port
  • 44.
    The crankshaft isrevolving clockwise and the piston is moving up the cylinder, compressing the charge of air. Because energy is being transferred into the air, pressure and temperature increase. By the time the piston is near the top of the cylinder (known as Top Dead Center or TDC) the pressure is >100 bar and the temperature > 500°C
  • 45.
    Just before TDCfuel is injected into the cylinder by the fuel injector. The fuel is "atomised" into tiny droplets. Being very small, these droplets heat up very quickly and start to burn as the piston passes over TDC. The expanding gas from the fuel burning in the oxygen forces the piston down the cylinder, turning the crankshaft. It is during this stroke that work energy is being put into the engine; during the upward stroke of the piston, the engine is having
  • 46.
    As the pistonmoves down the cylinder, the useful energy from the burning fuel is expended. At about 110° after TDC the exhaust valve opens and the hot exhaust gas (consisting mostly of nitrogen, carbon dioxide, water vapour and unused oxygen) begin to leave the cylinder.
  • 47.
    At about 140ºafter TDC the piston uncovers a set of ports known as scavenge ports. Pressurized air enters the cylinder via these ports and pushes the remaining exhaust gas from the cylinder, "scavenging". The piston now goes past BDC and starts moving up the cylinder, closing the scavenge ports. The exhaust valve then closes and compression begins.
  • 48.
    The two strokecycle can also be illustrated on a timing diagram. 1 -2 Compression 2 - 3 Fuel Injection 3 - 4 Power 4 - 5 Exhaust Blowdown 5 - 6 Scavenging 6 - 1 Post Scavenging 1. approx 110º BTDC 2. approx 10º BTDC 3. approx 12º ATDC 4. approx 110º ATDC 5. approx 140º ATDC 6. approx 140º BTDC
  • 49.
    4 5 5 6 4 PISTON POSITION 6 7 3 7 3 2 8 8 2 1 1 PRESSURE
  • 50.
    • 1-2 Scavenging period, both exhaust and inlet ports are open. • 2-3 Scavenge stroke ends. Exhaust ports remain open to ensure only fresh air remains in the cylinder. • 3-4 Compression takes place. Both ports closed. The air is then compressed by the upward movement of the piston. • 4-5-6 Fuel injector is operational supplying fuel oil. • 6-7 Due to expansion of gases, piston moves downward. (Power stroke) • 7-8 When piston crown/top ring passes the exhaust ports, exhaust begins • 8-1 When the piston passes the inlet ports, Scavenging begins and fresh air fills the cylinder, thus pushing the remaining exhaust gases out
  • 51.
    Fuel Fuel injection injection begins ends ON POW SI ES ER R MP STR CO OK Rotation E Scavenge Scavenge ports ports close open Exhaust Exhaust SCAVENGE ports ports close open EXHAUST TWO STROKE TIMING DIAGRAM
  • 52.
    The 2 stroke crosshead engine works on exactly the same principle and cycle as the 2 stroke trunk piston engine.
  • 53.
    The disadvantages ofthe two stroke trunk piston engine are that: It has a low overall height, lubricating oil splashed up from the crankcase to lubricate the liner can find its way into the scavenge space, causing fouling and a risk of fire. There is also the likelihood of liner and piston skirt wear, allowing air into the crankcase. This can supply the required oxygen for an explosion should a hot spot develop. The crankcase oil must have additives which can cope with contamination from products of combustion, and the acids formed during combustion due to the sulphur in the fuel.
  • 54.
    The majority of2 stroke engines encountered at sea are of the "crosshead" type. In this type of engine the combustion space (formed by the cylinder liner, piston and cylinder head), and the scavenge space are separated from the crankcase by the diaphragm plate. The piston rod is bolted to the piston and passes through a stuffing box mounted in the diaphragm plate. The stuffing box provides a seal between the two spaces, stopping oil from being carried up to the scavenge space, and scavenge air leaking into the crankcase. The foot of the piston rod is bolted to the crosshead pin. The top end of the connecting rod swings about the crosshead pin, as the downward load from the expanding gas applies a turning force to the crankshaft. To ensure that the crosshead reciprocates in alignment with the piston in the cylinder, guide shoes are attached either side of the crosshead pin. These shoes are lined with white metal, a bearing material and they reciprocate against the crosshead guides, which are bolted to the frame of the engine. The crosshead guides are located in-between each cylinder. Using the crosshead design of engine allows engines to be built with very long strokes - which means the engine can burn a greater quantity of fuel/stroke and develop more power. The fuel used can be of a lower grade than that used in a trunk piston engine, with a higher sulphur content, whilst high alkalinity cylinder oils with a different specification to that of the crankcase oil are used to lubricate the cylinder liner and piston rings and combat the effects of acid attack.
  • 55.
    SCAVENGING • To ensurea sufficient supply of fresh air for combustion by removing all remaining exhaust gases by blowing with these fresh air. • Supercharging is a large mass of air that is supplied to the cylinder by blowing it in under pressure either by electrically driven auxiliary blower or exhaust gas driven turbocharger. • The flow path of the scavenge air is decided by the engine port shape and design and the exhaust arrangements.
  • 56.
    SCAVENGING PERIOD It canbe defined as a period when inlet and exhaust are open at the same time: • Remaining exhaust gas will be expelled from the cylinder through exhaust ports or exhaust valve (if fitted). • Fresh air which has collected in the scavenge manifold rush into the cylinder • Scavenging period: Normally when piston is at BDC, (or as per maker or engine design or the location of the ports itself)
  • 57.
    SCAVENGING METHODS • CROSS/DIRECT– FLOW SCAVENGING • LOOP SCAVENGING • UNIFLOW SCAVENGING
  • 58.
    Cross/direct flow scavenging Exhaust manifold Scavenge manifold
  • 59.
    Loop scavenging Exhaust manifold Scavenge manifold
  • 60.
    2 stroke enginesdo not have exhaust valves; With scavenge ports in the cylinder liner, they are fitted with exhaust ports located just above the scavenge ports. As the piston uncovers the exhaust ports on the power stroke, the exhaust gas starts to leave the cylinder. When the scavenge ports are uncovered, scavenge air loops around the cylinder and pushes the remaining exhaust gas out of the cylinder. This type of engine is known as a loop scavenged engine. Note that the piston skirt is much longer than that for a uniflow scavenged engine. This is because the skirt has to seal the scavenge and exhaust ports when the piston is at TDC.
  • 61.
    TWO STROKE ADVANTAGES •Compactness in relation to the power output. Not required to increase brake mean effective pressure or the engine speed to increase rating. (High bmep increases the stresses on engine components, greater rate of cylinder wear, whilst the alternative of higher speed, valve flutter may become a serious problem) • Each out-stroke being a working stroke gives more even turning for the same number of cranks, consequently a lighter flywheel may be employed. • The reversing operation of rotation is simplified since there is less valve gear to contend with.
  • 62.
    OTHER ADVANTAGES • Fewer moving parts and lower maintenance • Lower specific fuel consumption • No gear loss • Simplicity in construction • Longer life time • Higher reliability (product) • Low lubricating oil consumption • Better ability to burn low quality fuel oil
  • 63.
    FOUR STROKE ADVANTAGES •Good volumetric efficiency, good combustion characteristic and positive exhaust scavenging. • The thermal and mechanical efficiencies are slightly better than 2S engine. • Only half the quantity of the heat generated in the cylinders has to be dealt within a given time, so that efficient lubrication of the piston and cooling of the cylinder is more easily accomplished.
  • 64.
    OTHER ADVANTAGES • Lowerinitial cost for equivalent power • Ease of installation • Lower weight per unit power • Saving in weight and engine room length • Increased cargo capacity • Free choice of propeller speed through gearing • Suitable for electrical power take off
  • 65.
    Supercharging/Turbocharging • Process ofpushing a higher pressure air charge into the cylinder greater than atmospheric pressure, so that extra mass of air can be delivered into cylinder to burn more fuel and produce extra power. • Turbocharging can increase power output of engine by 60%
  • 66.
    Turbocharging • Very effectivepressure charging. • Utilizes 20% of waste heat in exhaust gas which contains 35% of fuel heat. • How?
  • 67.
    •By increasing massof air in cylinder, more fuel can be burned and correspondingly power output will be increased •Various methods can be adopted: –Electrically powered auxiliary blower –Utilization of heat energy from exhaust gas to drive a single stage impulse turbine directly coupled to a simple blower (free running unit) called exhaust gas turbocharger Turbocharger utilizes free energy of exhaust gases and hence improves efficiency of the engine
  • 68.
    Typical heat balanceof an engine Useful Output (Brake Power) 34% Cooling Loss 30% Exhaust Loss 26% Friction, Radiation, etc. 10% ------- Total Heat Input 100%
  • 69.
  • 70.
    Advantages • Increased powerfor an engine of the same size OR reduction in size for an engine with the same power output. • Reduced specific fuel oil consumption -> mechanical, thermal and scavenge efficiencies are improved due to less cylinders, greater air supply and use of exhaust gasses. • Thermal loading is reduced due to shorter more efficient burning period for the fuel leading to less exacting cylinder conditions.
  • 72.
  • 73.
    Design consideration • Types of fuel and fuel oil system design • Types of lubricating oil and lubricating oil systems • Cooling systems • Waste heat utilization systems • Intake and exhaust valve systems • Starting air systems • Instrumentation system • Control and automation system • Installation items • Safety features
  • 74.
    Summary • Principle of ICE • Theoretical Cycles • Basic principle of operations of working cycle • Cycle & Timing Diagram • Principles of Scavenging & Arrangements • Advantages of 2S & 4S • Structural differences • Overlap of Inlet & Exhaust
  • 75.
    References • Introduction to Marine Engineering, • Marine Engineering , Roy L. Harrington, SNAME, 198 • El-Hawary, F. (2001). Ocean Engineering Handbook. CRC Press, UK. • Calder, Nigel (2007): Marine diesel engine: maintenance, troubleshooting and repair.

Editor's Notes

  • #12 1.       The induction stroke takes air in ideally at constant volume, pressure at temperature. 2.       The compression stroke takes place from A to B.  The air is compressed adiabatically to about 1/20 of its original volume.  It gets hot. 3.       From B to C fuel is injected in atomised form.  It burns steadily so that the pressure on the piston is constant. 4.       From C to D the power stroke moves the piston down as adiabatic expansion takes place. 5.       D to A cooling and exhaust occurs.