External Combustion EngineInternal Combustion Engine
External Combustion (E.C) Engine is termed a reciprocating heat engine, where the working fluid is burned (or) heated outside the engine container. The heating of working fluid produces thermal energy which is converted to mechanical force or output.
There are two types of External Combustion engines:
Single PhaseDual Phase
Internal Combustion (I.C) Engine is a type of heat engine, where the combustion takes place between the working fluid (Fuel) using air as an oxidizer inside the combustion chamber.
The Internal Combustion Engine is classified on two bases:
On the basis of ignition
Spark Ignition Gasoline Engine: In this type of Internal combustion engine, the fuel and air are combined and sent to the cylindrical chamber of the engine where the combination is compressed and ignited during the power stroke, which ultimately results in moving the piston. Compression Ignition Diesel Engine: In this type of internal combustion engine, the air is sent to the cylindrical chamber of the engine and then gets compressed. As the air is compressed, the fuel is sprayed inside the chamber which causes ignition and further movement of the piston.
On the basis of Strokes
Two-stroke Engine Four-stroke Engine
Compression Ignition Diesel Engine (or) Diesel engines doesn’t have any spark plug for ignition but instead consist of a fuel injector, which sprays fuel inside the cylindrical chamber of the engine when air is compressed. Spark plugs are placed inside the Spark Ignition Engine, which is basically used to ignite the fuel and air mixture inside the combustion chamber when it is compressed.
Following are the part of the Diesel Engine:
Cylinder Block assemblyCylinder Head Fuel NozzlePiston and Connecting RodCrankshaftExhaust ValveFlywheelAir IntakeFuel injection system and assembly
Working of Diesel Engine:
The cylindrical block is the most significant part of a diesel engine. Inside the cylindrical chamber, contains a piston and connecting rod assembly and has an opening for Fuel intake e.g., Fuel Nozzle, and another for discharging the combusted gases through Exhaust Valve and during which the air entering the chamber gets compressed up to a higher temperature and ignited when Fuel is sprayed. When the piston moves, the cylinder head connected to it through connecting rod closes the Exhaust valve when the fuel injector is working and it closes the fuel nozzle when exhaust gases have to be discharged. The crankshaft and flywheel are connected to the piston assembly and it is used to reduce the vibration and smoothen the working of the engine.
Following are the main parts of the Spark Ignition Gasoline Engine:
Inlet valveExhaust ValveCylindrical ChamberPistonSpark PlugCrankshaft MechanismConnecting Rod assembly
Working of Spark Ignition Gasoline Engine:
Spark Ignition Gasoline Engine works on strokes e.g., Suction Stroke, Compression Stroke, Power Stroke, and Exhaust Stroke. The piston initially moves down and creates a vacuum which in turn allows the air and fuel mixture to enter the chamber through an inlet valve. As the piston is moving from the Top dead center (TDC) to Bottom Dead Center (BDC), this stroke is defined as a Suction stoke. Now, as the piston moves from the Bottom dead center (BDC) to the Top dead center (TDC), the mixture (Air + Fuel) will be compressed and this stroke is called a Compression stroke. In Power stroke, again piston moves from the Top dead center (TDC) to the bottom dead center (BDC) and thus the compressed mixture of air and fuel is ignited using a spark plug due to which combustion takes place. In exhaust stroke, the piston moves from the bottom dead center (BDC) to the Top dead center (TDC) and the exhaust gases are discarded through the exhaust valve. And, it completes one cycle of Spark Ignition Gasoline Engine.
Both the types I.C (Internal Combustion Engine) engine e.g., Spark ignition gasoline engine and Compressed Ignition Diesel Engine have different type of combustion tool e.g., Spark plug works only in Spark ignition engine and Fuel injector works only in Diesel Engine, Vice-versa isn’t possible for any system.
What are the Top dead and Bottom dead center?
The top dead center (TDC) is the position of the piston when it reached the top of its stroke. The bottom dead center (BDC) is defined as the position of the piston when it reached the bottom of its stroke.
What is a two-stroke engine?
A two-stroke engine is a type of Internal combustion (I.C) engine, which completes its one cycle in two strokes e.g., Intake, Compression, Power, and Exhaust. The whole process of taking the fuel inside and compressing it takes place in one stroke and the Combustion of fuel and Discharge of gases (Exhaust) takes place in another stroke.
