This presentation will guide the students about the basic principles of heat engines for engineering students.Deskripsi lengkap
This presentation will guide the students about the basic principles of heat engines for engineering students.Full description
Rankine Cycle for Waste Heat Recovery of IC EnginesFull description
Market analysis of turboshaft engines
string orchestra with percusion
For more FREE Geometry Study Material visit www.examville.comFull description
statutory constructionFull description
IMC
mythologyFull description
Full description
Classification systems including angle n ackermann profittDeskripsi lengkap
gfhhvbncFull description
Full description
introduction to nanomaterials
thinkiit prefoundation class x chemistry
English Grammar - PhrasesFull description
Tell the basic classification of dryers
Notes on the topic 'Periodic classification of elements' for class X
Full description
D. Arumuga Perumal Asst. Professor (senior) / SMBS Vellore Institute of Technology Vellore
Coverage / Objective • • • •
Types of internal combustion engines Thermodynamic principles involved Components and purposes of each Operation of systems – Four stroke engines – Two stroke engines
Classification of Heat Engines Heat Engines
External Combustion Engines
Rotary Engines
Internal Combustion Engines
Reciprocating Engines
Reciprocating Engines
2 – Stroke Engines
S.I Engine
C.I Engine
4 – Stroke Engines
S.I Engine
C.I Engine
S.I & C.I engines
•
In 1867, Nikolaus August Otto, a German engineer, developed the fourstroke "Otto" cycle.
•
Spark Ignited (SI) engine works on Otto Cycle. S.I engines use Gasoline, LPG and Alcohol based fuels. For initiating ignition these engines use Spark Plug
•
The Diesel Engine came about in 1892 by another German engineer, Rudolph Diesel. The Diesel engine is designed heavier and more powerful than gasoline engines and utilizes oil as fuel. Diesel engines are a commonly used in heavy machinery, locomotives, ships, and automobiles
•
Compression Ignition (CI) or Diesel Engines engine works on Diesel cycle. CI engines uses Diesel , Bio-diesel and Bio based oils
4-Stroke Engines
Main parts of the 4 - stroke engine Can be classified into 1. Structural Components 2. Moving components
Four Strokes –
1. Suction Stroke
2. Compression Stroke
3. Expansion stroke 4. Exhaust stroke •
These four strokes require two revolutions of the crankshaft
Engine Stroke
•
Engine stroke – A stroke is a single traverse of the cylinder by the piston (from TDC to BDC) – 1 revolution of crankshaft = 2 strokes of piston
Otto Cycle (4- Stroke SI Engines)
4-Stroke SI Engine
•
The Intake Valve opens at a precise time to allow the air/fuel mixture to enter the cylinder
•
The Spark Plug ignites the air/fuel mixture in the cylinder, which creates an explosion
•
The Exhaust Valve opens at a precise time to allow the burned gases to leave the cylinder
•
The force of the explosion is transferred to the Piston
•
The force from the piston is then transferred to the Crankshaft through the connecting rod
•
The piston travels up and down in a Reciprocation Motion
•
The crankshaft converts the reciprocating motion of the piston, to the Rotating Motion
Diesel Cycle (4-StrokeCI Engines) •
The Diesel engine differs from the gasoline engine in that the intake stroke only pulls in air, not air and fuel. The fuel is injected into the cylinder at the end of the compression stroke. The fuel burns immediately (without the use of a spark plug) because of the high temperature of air in the cylinder.
2- Stroke Engines Main Parts Spark Plug Piston Inlet Port Exhaust Port Transfer Port Crank Case
Intake. The fuel/air mixture is first drawn into the crankcase by the vacuum created during the upward stroke of the piston. The illustrated engine features a poppet intake valve, however many engines use a rotary value incorporated into the crankshaft Compression. The upward stroke of the piston compresses the fuel mixture. (At the same time, intake stroke is happening beneath the piston).
Power. At the top of the stroke the spark plug ignites the fuel mixture. The burning fuel expands, driving the piston downward, to complete the cycle
During the downward stroke the poppet valve is forced closed by the increased crankcase pressure. The fuel mixture is then compressed in the crankcase during the remainder of the stroke.
Transfer/Exhaust. Towards the end of the stroke, the piston exposes the intake port, allowing the compressed fuel/air mixture in the crankcase to escape around the piston into the main cylinder. This expels the exhaust gasses out the exhaust port, usually located on the opposite side of the cylinder. Unfortunately, some of the fresh fuel mixture is usually expelled as well.
Four stroke engines
Two stroke engines
2 revolutions of
One revolution of crankshaft
crankshaft Turning moment is not uniform – heavier flywheel Less power for same size Lesser cooling &
Uniform turning moment lighter flywheel More power for same size Greater cooling & lubrication requirements
lubrication requirements
Less
More volumetric efficiency
Low
Higher thermal efficiency Higher initial cost
Low
SI ENGINES
CI ENGINES
Otto cycle
Diesel cycle
Gasoline/ or petrol
Diesel oil
Introduction of fuel – air mixture at suction stroke
