Lecture 1 Flashcards
In thermodynamics and engineering, is a device which transforms
the chemical energy of a fuel into thermal energy and uses this energy to produce useful mechanical work
The term is also used to all devices that produces useful
work either from combustion of a fuel or heat transfer through heat exchangers.
heat engine
Classification of Heat Engine
Heat engine may be characterized by the following:
- It absorbs heat energy from higher temperature source
- Some of heat absorbed will be converted into mechanical work
- The remaining heat that is not converted into mechanical workwill be rejected to
the lower temperature sink
Heat Engine is majorly categorized into two types
- External combustion engine
- Internal combustion engine
In this engine, the combustion process takes place outside the cycle boundaries and the thermal energy (heat) is transfer to the working fluid through heat transfer. It uses different source for different type of cycle such as furnace, heat recovery steam generator, geothermal well and nuclear reactor
- Power Plant that uses steam as working fluid i.e. coal power plant, geothermal power
plant, nuclear power plant, combined cycle power plant, solar power plants, etc. - In a closed cycle gas turbine, which uses secondary fluid such as helium, hydrogen,
air or argon etc.
External Combustion Engine
In this engine, the combustion takes place within the cycle boundaries and used as the direct motive force. In an internal combustion engine, to generate useful mechanical energy, the thermodynamic expansion of the high temperature and pressure gases, which are produced by the combustion, directly applies force to a movable component of the engine.
Internal Combustion Engine
Comparison between external combustion engine and internal combustion engine.
- Combustion of air-fuel is outside the engine cylinder or outside the system boundaries vs inside the engine cylinder.
- The engines are running smoothly and silently vs noisy operated engine.
- Heavy and cumbersom vs lightweight and compact.
- It can use cheaper fuels including solid fuels vs high grade fuels, mostly liquid and gaseous fuels.
- Higher requirement of water for rejection of heat through cooling system vs Lesser requirement for water since air can also be used as a cooling medium.
- Takes a lot of time in engine start-up vs Quick engine start-up.
- Self-starting vs not self-starting
According to the cycle of operation or the number of stroke per cycle-
(a) Two stroke engine
(b) Four stroke engine
According to the motion of movable components
(a) Reciprocating engine (Use of cylinder piston arrangement),
(b) Rotary engine (Use of turbine)
According to the valve location
(a) I head Engine – valves are located at cylinder head or usually called
Overhead Valve
(b) L head Engine/ T head Engine – valves are located at cylinder block
or usually called as Flat head Valve.
(c) F head Engine – one valve is positioned on cylinder head and one in the cylinder block
According to the type of fuel used-
(a) Petrol engine
(b) Diesel engine
(c) Gas engine (CNG, LPG)
(d) Alcohol engine (ethanol, methanol etc)
According to the method of igniting the fuel-
(a) Spark ignition engine (S.I) – igniting the fuel using Spark Plug
(b) Compression ignition engine (C.I) – self-ignites due to high
temperature in the combustion chamber caused by high
compression
According to the number of Cylinders
(a) Single Cylinder
(b) Multi-Cylinder
According to the working cycle-
(a) Otto cycle (constant volume cycle) engine,
(b) Diesel cycle (constant pressure cycle) engine
(c) Dual combustion cycle (combination of Otto and Dual cycle) engine,
(d) Open-Brayton cycle
According to the positioning or arrangement of Cylinders (for reciprocating multicylinder engine)
- In-line or straight
- V engine
- W engine
- Opposed Cylinder
- Opposed piston
- Radial engine
According to air intake process
(a) Naturally Aspirated.
No intake air pressure boost system.
(b) Supercharged.
Intake air pressure increased with the compressor driven off of the engine crankshaft
(c) Turbocharged.
Intake air pressure increased with the turbinecompressor driven by the engine exhaust gases
(d) Crankcase Compressed.
Two-stroke cycle engine which uses the crankcase as the intake air compressor
According to methods of Fuel Input for SI Engines
(a) Carbureted.
(b) Multipoint Port Fuel Injection. One or more injectors at each cylinder intake
(c) Throttle Body Fuel Injection. Injectors upstream in intake manifold.
According to Application
(a) Automobile, Truck, Bus.
(b) Locomotive
(c) Stationary: Industrial engine and Prime mover for electrical
generators
(d) Marine Propulsion
(e) Aircraft Propulsion
(f) Small Portable: Chain Saw, Grass cutter
According to Method governing
(a) Hit and miss governed engines,
(b) Quantitatively governed engines
(c) Qualitatively governed engine
Method of Starting
(a) Manual: Rope, crank, kick
(b) Electric: Battery and electric motor
(c) Compressed air
(d) Using of other engine
The first fairly practical gas engine. Brake thermal efficiency up to 5%.
A single-cylinder, two-stroke engine with electric ignition of ilumination gas (not gasoline).
1860 Jean J. Lenoir
Patents a two-stroke internal combustion engine building on Lenoir’s. Patents a practical four-stroke internal combustion engine.
1867 & 1877 Nicolaus A. Otto
Invernted ________’s Ready Motor and went into commercial production, this used constant pressure combustion, and was the first commercial liquid fuelled internal combustion engine.
1872 George Brayton
Invernted ________’s Ready Motor and went into commercial production, this used constant pressure combustion, and was the first commercial liquid fuelled internal combustion engine.
1872 George Brayton
Development of compression ignition engine which is the same _____ engine known today.
1892 Rudolf Diesel
Development of ______ engine which is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.
1957 Felix Wankel
Also called piston engine. An engine in which the piston moves up and down or back and forth, as a result of combustion in the top of the cylinder.
Reciprocating Internal Combustion Engine
Body of engine containing the cylinders, made of cast iron or aluminum. The block of water-cooled engines includes a water jacket cast around the cylinders. On air-cooled engines, the exterior surface of the block has cooling fins
Block
A rotating lobe of irregular shape or eccentric or offset portion of the shaft (cam). It changes rotary motion of cam shaft to reciprocating or variable motion of valve lifter resting on it.
Cam
– A part which is held in contact with the cam and to which the cam motion is imparted and transmitted to the push rod
Cam follower (valve lifter)
The shaft in the engine which has a series of cam lobes (simply called
cams) for operating the valve mechanisms, driven by gears or sprockets and chain from the crankshaft. It is used to push open valves at the proper time in the engine cycle
Cam shaft
Metal fins on the outside surfaces of cylinders and head of an aircooled engine. These extended surfaces cool the cylinders by conduction and convection.
Cooling fins
The end of the cylinder between the head and the piston
face where combustion occurs.
Combustion chamber
: A link that connects the piston with the rotating crankshaft,
usually made of steel or alloy forging in most engines but may be aluminum in
some small engines.
Connecting rod
A device for converting reciprocating motion of the piston into rotary
motion of the crank shaft
Crank
It houses cylinder and crankshaft of the IC engine and also serves as
sump for the lubricating oil.
Crank case
The main rotating member, or shaft running along the length of the
engine.
The _____ is connected to the engine block with the main bearings. The special steel alloys are used for the manufacturing of the _______. It consists of eccentric portion called crank
Crankshaft
It is the main part of the engine inside which piston reciprocates to
and from. The ordinary engine is made of cast iron and heavy duty engines are
made of steel alloys or aluminum alloys. In the multi-cylinder engine, the cylinders are cast in one block known as cylinder block
• Cylinder
It is the main part of the engine inside which piston reciprocates to
and from. The ordinary engine is made of cast iron and heavy duty engines are
made of steel alloys or aluminum alloys. In the multi-cylinder engine, the cylinders are cast in one block known as cylinder block
• Cylinder
The basic framework of the engine to which the other engine
parts are attached. It includes the engine cylinders and the upper part of the crankcase
Cylinder block
The top end of the cylinder is covered by cylinder head over
which inlet and exhaust valve; spark plug or injectors are mounted.
Cylinder head
Piping system which carries exhaust gases away from the
engine cylinders, usually made of cast iron.
Exhaust manifold
Rotating mass with a large moment of inertia connected to the
crankshaft of the engine.
The purpose of the ____ is to store energy and furnish a large angular momentum that keeps the engine rotating between power strokes and smooths out engine operation.
On some aircraft engines the propeller serves as the ___, as does the rotating blade on many lawn mowers.
Flywheel
Rotating mass with a large moment of inertia connected to the
crankshaft of the engine.
The purpose of the ____ is to store energy and furnish a large angular momentum that keeps the engine rotating between power strokes and smooths out engine operation.
On some aircraft engines the propeller serves as the ___, as does the rotating blade on many lawn mowers.
Flywheel