HISTORY & BASICS OF INTERNAL COMBUSTION ENGINE

 

HISTORY & BASICS OF

INTERNAL COMBUSTION

ENGINE

  1. ICE concept started 150 years earlier.

  2.  Engine creator—Etienne Lenoir in 1859.

  3. ICE Modern engine creator Siegfried

  4. Marcus in 1864,

  5. Power producing capacity 5 W to 100000 kW.

It is a heat engine. Input is heat. Motion /

work / electricity is the output. In this,

combustion of Hydrocarbon fuels occurs

with an oxidizer(Oxygen but usually air). In

the Combustion chamber,  fuel burns.

High pressure and high temperature gases

 move a piston in

the internal combustion engine. Chemical

energy is first converted into heat energy.

Next conversion is into pressure energy,

mechanical energy and finally power is

produced. There are different ways

to classify the internal combustion engines

There are number of parts and fuels

in a internal combustion engine. Various

parts of specific materials are

manufactured with prescribed methods of

manufacture. Use specific fuels to

give best performance with least troubles.

Highlights are key features which help in

the selection of the internal combustion

engine. The better selection is useful from

all angles. Question answers are very

helpful in understanding. This also

increases clarity. Then it will be easy to use

the information in real life.

Start of motion

 Piston cylinder arrangement or turbine blade rotates the shaft.  High temperature and high pressure combustion gases produce motion. Gases obtained from  the Hydrocarbon fuel. Thus produce mechanical power.

Working types

Steady power producing types (Continuous)
 Unsteady power producing types (Intermittent type)

Steady power continuous production type

Three types

  1. Gas turbine-Uses compressor and turbine and not the piston cylinder. Under this category, there are of three types.
  2. Turbo-shaft
            A turbo-shaft engine is a form of gas turbine. It  produces total shaft work to run the propeller and generator. There is no jet at all. Turbo-shaft engines run a small powerful light weight engine. Helicopters and auxiliary power units use turbo shaft.
(a) Turbofan
Partly shaft work and partly Jet produce power. In this, there is by pass air because there is a fan in front of it. There are low by pass engines such as MD-80. The high by pass turbofan is model 747-400.
(b) Turbojet
All jet produce power.  Shaft work  runs the compressor. A turbojet engine does not have any by-pass air. There is no fan in it. Example is engine DC-9.
3. Ramjet
No turbine no compressor.  Ramjet has no moving parts. Air enters the supersonic aircraft .  Diffusers slow down air and compress air. Expansion of hot gases accelerates exhaust air to a velocity higher than that at inlet. It thus creates positive thrust. It uses high Mach number Ramming effect (instead of compressor) and produce power.
Rocket engines—All jet work and no shaft work at all

Non-steady power production Intermittent type

Two types

  1. Petrol Engines–Premixed fuel and air, then compressed and ignited with spark plug—-further of two types
(a) Two stroke—Completes cycle in one rotation of the engine or 1 power stroke in 1 rotation of the engine
(b) Four stroke—Completes cycle in two rotations of the engine or 1 power stroke in 2 rotations of the engine
2. Diesel engines
(i) No pre-mixing of fuel and air
(ii)  High compression ratio compresses air
(iii) the fuel injected into the cylinder
(iv) High temperature of compressed air burns fuel
It is further of two types

 SPECIAL INTERNAL COMBUSTION ENGINES

Smallest internal combustion engine

  1. Model: Cox Tee Dee 010
  2. Weight: 0.49 oz.
  3. RPM: 30,000
  4. Power: 5 watts
  5. Ignition with a Glow plug
  6. Fuel used: castor oil (10 – 20%),  nitro-methane (0 – 50%), balance  methanol
  7. Power/weight = 0.22 hp/lb
  8. Poor performance as efficiency < 5%
  9. Emissions with high foul smell
  10. Very noisy
  11. Used in model airplanes

Largest power producing  internal combustion engine without shaft work

  1. Space Shuttle Solid Rocket Boosters
  2. Power =  42000000 horsepower (42 million HP)= 31330 MW
  3. Power/weight = 32 hp / lb
  4. No shaft power
  5. kinetic energy of exhaust stream produce work
  6. Used in Space Shuttle

Largest power producing  internal combustion engine with shaft work

  1. Model: Siemens SGT5-8000H
  2. Power= 456000 HP =340 MW
  3. Power/weight = 0.52 hp/lb
  4. Stationary gas turbine
  5. Used for electrical power generation

Largest Size Internal Combustion Engine

  1. Model: Wartsila-Sulzer RTA 96-C
  2. Turbocharged
  3. Two-stroke diesel
  4. Built in Finland
  5. 14 cylinder
  6. Weight 2300 tons
  7. Length 89 feet
  8. Height 44 feet
  9. power 108,920 hp @ 102 rpm (81 MW)
  10. torque 5,608,312 ft lb @ 102 RPM
  11. Power/weight = 0.024 hp/lb
  12. Efficiency 51%,  Most efficient IC engine
  13. Used in container ships

SELECTION INTERNAL COMBUSTION ENGINES

(i) On the basis of  the engine cycle used

(a)  Two stroke engine
(b) Four stroke engine (Otto cycle)
(c) Six stroke engine
(d) Diesel engine
(e) Atkinson cycle engine
(f) Miller cycle engine

(ii) On the basis of the layout of the engine

 Reciprocating and rotary

(iii) On the basis of source of energy

Combustion of fuels like
          (a) Petroleum spirit, Petroleum diesel, Auto-gas (liquefied petroleum gas), compressed natural gas and jet fuel
         (b)  Coal: Gasoline and diesel fuels
          (c) Bio-fuels and vegetable oils: Peanut oil and other vegetable oils
          (d) Wood gas: From wood gasifier using solid wood as a fuel
           (e) Bio-fuels: Bio-diesel, Bio-butanol, Di-methyl ether, Bioethanol, Bio-                   methanol and bio-gas

(iv) On the basis of the type of use of the engine

(a) Stationary units as generators
(b) Moving units like all vehicles
(c) Gas turbines producing large amount of power as in aircrafts

(v) On the basis of the cooling system employed

(a) Cooling saves the engine from overheating. Overheating may cause cracking or warping. Two most common methods of engine cooling are
air cooling
water cooling 
both simultaneously air & water cooling.
PRACTICAL APPLICATIONS OF INTERMITTENT POWER PRODUCING INTERNAL COMBUSTION ENGINES (FOUR STROKES)
  1. Automobiles
  2. Motorcycles
  3. Scooters
  4. Water Ships
  5. Locomotives
  6. Generators
PRACTICAL APPLICATIONS OF INTERMITTENT POWER PRODUCING INTERNAL COMBUSTION ENGINES (TWO STROKES)
  1. Motorcycles
  2. Mopeds
  3. Lawnmowers
  4. Snowmobiles
PRACTICAL APPLICATIONS OF CONTINUOUS POWER PRODUCING INTERNAL COMBUSTION ENGINES
  1. Aircrafts
  2. Helicopters
  3. Jet engines
  4. Rockets

GROUND CLEARANCE

Ground clearance is the vertical distance between the road surface and the lowest part of the vehicle. Minimum ground clearance in Indian passenger cars is 160 mm. Lowest part of vehicle does not tough a speed breaker. It varies from one vehicle to another vehicle.

TRACK WIDTH

Track width is the distance between the centers of two tires on the same axle. It varies from one vehicle to another vehicle. On most vehicles, front track width and rear track width is different since they perform different functions.

REAL TRACK WIDTH

Distance between outer wheel edge on left to outer wheel edge on right excluding the mirrors.

TURNING RADIUS

The turning radius is the radius of the smallest circle (i.e. When taking an U TURN) that the vehicle is capable of taking. It varies from one vehicle to another vehicle.

WHEELBASE

The distance from the center lines of front & rear axle is wheelbase. It varies from one vehicle to another vehicle. A car with longer wheelbase gives sufficient space for the legs of the driver. It provides for better control in driving and also gives lesser fatigue.

APPROACH ANGLE

Approach angle is the angle of a hill a vehicle can climb up without scraping its front end.

DEPARTURE ANGLE

Departure angle is the angle of hill a vehicle can climb down  without scraping its rear end.

CARGO VOLUME

Cargo volume is the total volume of space in a vehicle cargo area.

HEADROOM

Headroom is the vertical distance from vehicle inside roof ceiling to inside floor level.

HEIGHT

Height is the vertical distance from the road level to the vehicle highest point. It is important from garage height or flyover height.

HIP ROOM

It is width of the seat.

LENGTH

It is the horizontal distance of a vehicle from front tip to the farthest point in back.

SHOULDER ROOM

It is the horizontal inside distance from one door to the opposite door on front or back.

INTERNAL COMBUSTION ENGINE PARTS & FUELS

Details of Parts

Part name

Method of manufacture

Material of construction

Function

Cylinder
Casting
Cast iron
Guides and supports the piston
Cylinder Head
Casting
Cast iron
Contains suction valve and exhaust valve. Suction valve is for the intake of petrol air mixture. Exhaust valve is for exhaust of gases.
Crankcase
Casting
Cast iron
Houses crankshaft and bearings.
Sump
Casting
Aluminum alloy
 Lower part of crankcase joins with it and contains the lubricating oil.
Piston
Casting
Cast iron
It is a tight plunger moving in the cylinder to and fro.  Small end of the connecting rod connects to piston with a Gudgeon Pin. Piston contains grooves for the piston rings.
Piston rings
Casting
Cast iron
Circular rings of rectangular section fitted in the piston grooves. These stop the leakage of gas mixture and lubricant across the piston.
Gudgeon Pin
Casting
Cast iron
It connects small end of the connecting rod to the piston. It provides a to and fro motion to the Connecting rod.
Connecting rod
Casting
Cast iron
Piston connects to small end of connected rod with a Gudgeon pin. Connect big end to the crankshaft. It has an oscillating motion (neither straight line motion nor circular motion). It transfers the pressure on the piston as a torque on the crankshaft.
Crankshaft
Casting
Cast iron
Crankshaft is a circular rod.  Bent it twice  in perpendicular direction. This  accommodate the big end of the connecting rod. This helps to convert the straight-line motion into a rotary motion of the crankshaft.
Crank Throw Or Crank Radius = R
————-
———–
Distance from the center line of crankshaft and center line of big end of the connecting rod
TDC=Top dead center
——–
——-
Position of piston near the cylinder head
BDC = Bottom Dead Centre
——–
——-
Position of Piston near the open end of the cylinder
TDC & BDC
——–
——-
Two extreme position of the piston
Stroke length L = 2R
——–
——-
Distance between TDC and BDCR is crank throw or R is crank radius
Flywheel
Casting
Cast iron
 A heavy wheel mounted on crankshaft. This stores excess energy from the power stroke. It  supplies back energy during the three non power strokes.
Clearance volume
———-
————
Space between the cylinder head and TDC. It is essential as piston will not now strike the cylinder head and the life of the engine will increase.
 FUELS
Fuel burning produces heat energy in IC engines. Therefore, selection of fuel is extremely important. However, selection will depend upon the characteristics of the fuel. Fuel used will affect the design, durability (life) and thermal efficiency of the internal combustion engine. Fuel selection will also depend on the atmospheric pollution capability. Various types of fuels can be solid, liquid and gaseous fuels. Solid Fuels
  1.  Earlier time used powered coal. Now it is no longer in use these days because of handling, storage and ash disposal problems.
  2. Gaseous Fuels
  3. Gaseous fuels are also not suitable because of handling, storage and fire risks involved. Stationary plants use LPG.  LPG fuels reduce the storage problems. However safety concern still exits. Thus gaseous fuels are also not much in use.
  4.  Internal combustion engine use liquid fuels. Petrol and diesel are most common. Petroleum give petrol and diesel. Petroleum is a mixture of hydrocarbons having different molecular structures. Various hydrocarbons in the petroleum are Paraffin, Olefin, Naphthalene and aromatics.
TABLE: Hydrocarbons in Petroleum
Petroleum
Hydrocarbon
General
formula
Type of
Molecular
Structure
Type of
bond
Saturated/
Unsaturated
Stable/
Unstable
Paraffin
(CH4, C2H6, C3H8, C4H10 etc.)
CnH2n+2
Chain
Single
Saturated
Stable
Olefin
(Hexene,
Butadiene)
CnH2n
Chain
Single bond with One or more double bonds
Unsaturated
Unstable
Naphthalene
(Cyclo-pentane)
CnH2n
Ring
Single
Saturated
Stable
Aromatics
(benzene C6H6, Toluene C6H5CH3)
CnH2n–6
Ring
Single and double bonds
Highly
Unsaturated
Highly Unstable
 

ADVANTAGES OF LIQUID FUELS IN IC ENGINES

  1. Requires less storage.
  2. Makes the engine compact
  3. Handling is convenient
  4. Available in abundance
  5. Available everywhere
  6. Cheaper than other fuels
  7. High Power/weight & power/volume can be achieved in light vehicles using petrol
  8. High energy/weight ratio is achievable
  9. Relatively safer than hydrogen or nuclear plants.

HIGHLIGHTS INTERNAL COMBUSTION ENGINES

The followings are the highlights of the internal combustion engines:

  1.  There is one working stroke in one revolution in a two stroke cycle, .
  2. In a four stroke cycle, there is one working stroke in two revolutions.
  3.  Scavenging is forcing out of exhaust gases in petrol & diesel engines..
  4.  During the discharge stroke in a four stroke engine, used gases go out.
  5.  In the case of two stroke, fresh charge enters at a high velocity. Used gases go out at the same time.
  6. Application of four stroke petrol engines are for light vehicles. These are cars, jeeps and small power generating sets.
  7. Two stroke petrol engines are for very light vehicles. These include motor cycles, scooters, three wheeler and portable crop sprayers.
  8.  Heavy machinery use four stroke diesel cycle. These include
               i. Diesel power plants

ii. Trucks

iii.  Buses

iv. Road rollers

v. Water pumps

vi. Diesel locomotives

vii. Tractors

viii. Marine engines use two stroke diesel cycle.

     i. Complete combustion requires stoichiometric air-fuel ratio.  For a petrol engine, the AFR is around 14.7:1.  1 kg of petrol requires 14.7 kg of air for complete combustion.

      j. With more air-fuel ratio, mixture is lean mixture. With less  air-fuel ratio, mixture is rich mixture. For a petrol engine, if the air fuel ratio is 16:1, it will be a lean mixture. If the air fuel ratio is 10:1, it is a rich mixture.

       k. Air fuel ratio even for diesel is almost the same.

       l. Petrol engine uses a spark plug to ignite the mixture.  Higher compression ratio ignites diesel.

       m. Starting, idling and maximum power generation require rich mixture.

        n. It never requires a lean mixture. It results in wastage of fuel.

        o. There are two methods of fuel injection in diesel engines. These are  air blast injection and airless (or solid) injection.

         p. Combustion of the fuel produces a high temperature of 2500 0 C temperature. Piston and other parts may not withstand such high temperatures.   Engine cooling reduces temperature.

          q. Detonation is sudden rise of temperature and pressure in the cylinder with a loud sound. Reduction of detonation is desirable.

           r. Chemicals added to suppress detonation are Dopes.

           s. Supercharging is the process of increasing the density of the air fuel mixture in petrol engines. Compression increases the density of air in diesel engines.

            t. Highlights of the internal combustion engines helps in the proper selection of an engine for a particular application