Introduction Lecture 1 1
Outline In this lecture we will learn about: Definition of internal combustion Development of the internal combustion engine Different engine classifications We will also draw a comparison between the S.I. Engines and the C.I. Engines. 2
Introduction The Internal Combustion (I.C.) engine is a heat engine that converts chemical energy (in the fuel) into mechanical energy (available on a rotating shaft). Internal Vs. External combustion. History: 1859 Discovery of oil. 1876 First four stroke spark ignition engine produced by Nicholas Otto. 1888 Pneumatic rubber tire invented by John Dunlop 1892 First compression ignition engine produced by Rudolph Diesel. 3
Internal combustion engines can be classified in a number of ways: Basic Design: Reciprocating: Piston- Cylinder arrangement Rotary: Rotor-Stator arrangement 4
Type of ignition: Spark Ignition (S.I.) Compression Ignition (C.I.) Engine Cycle: Four-Stroke Cycle: four piston movements over two engine revolutions / cycle Two-Stroke Cycle: two piston movements over one revolution / cycle 5
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Valve Location: In the head (overhead valve / I head ) In the block (Flat head / L head ) One in the head, one in the block (F head) 8
Position and number of cylinders: In-line (straight): most common 4 cylinders V Engine: V6 and V8 most common 9
Opposed cylinder (flat): small aircrafts Opposed piston 10
Radial Engine: large aircraft and ship engines W Engine: rare racing purposes Single cylinder: research purposes 11
Method of fuel input (S.I. engines): Carburetted Fuel Injection: Multipoint port fuel injection (at the cylinder intake) Throttle body fuel injection (in the manifold) 12
Air intake system: Naturally aspirated Charged (Intake air pressure increased): Supercharged: using compressor driven by crankshaft Turbocharged: turbinecompressor driven by exhaust gases flow 13
Type of cooling: Air cooled Liquid cooled Fuel used: Gasoline (Petrol / Benzene) Diesel Other (Gas, LPG, Alcohol.etc) 14
Application: Automotive Locomotive Aircraft Marine Stationary Small portable 15
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(S.I. Engines) Vs. (C.I. Engines) Fuel Economy: C.I. engines are more economic due to the higher thermal efficiency (30-40% compared to 20-30 %) because of the higher compression ratios. Power and torque: S.I. engines are more powerful at higher speeds due to their shorter stroke and wider speed range. Reliability: C.I. engines are more robust, run cooler and generally have a longer life. 17
(S.I. Engines) Vs. (C.I. Engines) Safety: Fire risk is less in C.I. engines since diesel (unlike petrol) is not flammable at normal operating temperatures. Cost: C.I. are more expensive due to their heavy construction and advanced injection equipment. Pollution: C.I. engines produce less CO and CO 2 but more NO x and much more particulates (soot). 18
Activity #1 In teams of 2 students each: Pick a modern passenger car model and examine its engine. Then classify this engine according to the engine classifications discussed in this lecture. Submit your report within one week from today. 19