Weitere ähnliche Inhalte Ähnlich wie I.c. Engine Testing and Pollution Control (20) Mehr von Aditya Deshpande (20) Kürzlich hochgeladen (20) 2. I.C. ENGINE TESTING AND
POLLUTION CONTROL
Purpose Of I.C. Engine Testing
1. To get information which is not possible by calculations
2. To confirm the validity of data used while designing engine
3. To satisfy customer as to rated power with guaranteed fuel
consumption
The tests carried out are of two types:
1. Commercial TESTS
2. Thermodynamic TESTS
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3. Commercial Tests
1. Rated o/p with guaranteed fuel consumption
2. Qty. Of lubricating oil consumed
3. Qty. Of cooling water consumed
4. Steadiness of engine under varied load conditions
5. Overload carrying capacity of engine
Thermodynamic Tests
1. These are carried for purpose of comparing actual
results with theoretical performance.
2. In this, it is necessary to measure losses, and to
draw a heat balance account.
3. After this tests are carried, performance is
compared with earlier records
4. For this measurement some terminologies are
important they are:
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4. INDICATED POWER(IP)
• The power developed inside engine cylinder is known as indicated
power.
• It is denoted by IP.
• IP of engine can be measured by fitting instrument known as
indicator on cylinder
Where,
IP = PmALN
Pm = Mean effective pressure
A = C/S area of cylinder
L = Length of stroke
N = Number of power stroke
For Two Stroke Cycle
Engine
For Four Stroke Engine
For N revolution we get N
power strokes
IP = PmALN
= Pm ∏/4 d2LN
For N revolution we get N/2
Power strokes
IP = PmALN
= PmAL N/2
= Pm ∏/4 d2 N/2
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5. BRAKE POWER (BP)
Brake of an engine is useful power available at the crank. It is denoted by BP
Brake power is less than indicated power because:-
1. Friction between cylinder surface and piston rings, bearings,gears,valve etc.
2. Pump loss due to induction and exhaust.
3. Resistance of air to flywheel .
4. Power required to drive auxiliaries, fuel pump, governor, lubricating pump,
5. Water circulating pump.
It is measured by the use of either a
mechanical, electrical or hydraulic dynamometer.
The brake power can be given as :
BP = (W – S )r × 2 ∏N
where, W = Dead weight
S = Spring balance reading
R = Brake drum radius
N = speed of engine.
Also, Net break load = (w – s ) and Brake torque = (w – s).r
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6. FRICTIONAL POWER (FP)
The difference between the indicated power and brake power is known
as
Frictional Power.
It is the power lost in overcoming the friction. It is denoted by FP.
IP = BP + FP
FP = IP – BP
Frictional power can be measured by
1. motoring test,
2. Williams straight line method
3. or morse test.
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7. EFFICIENCIES OF I.C. ENGINE
It is a measure of mechanical perfection of the engine or its ability to transmit power
Developed In the engine cylinder to the crank shaft.
It is defined as ‘the ratio of brake power to indicated power of engine’.
Mechanical efficiency = Brake power
Indicated power
= Brake power
Brake power + Frictional power
1. Mechanical efficiency of engine varies with the load.
2. When load on engine is decreases Efficiency falls down.
3. Also efficiency decreases with increase in speed.
Thermal Efficiency:
It is the ratio of power output (developed) to the heat energy of he fuel supplied
During the same duration.
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8. Brake Thermal Efficiency :
The efficiency based on the brake power is known as brake thermal efficiency, and
Given as:
= Heat equivalent of brake power
Heat supplied
= BP in kW
Mass of fuel in kg/sec × CV n kJ/kg
Indicated Thermal efficiency :
Efficiency based on Indicated power is termed as indicated thermal
Efficiency and is given as:
= Heat equivalent of indicated power
Heat supplied
= IP in kW
Mass of fuel in kg/sec × CV n kJ/kg
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9. Relative Efficiency :
It is the ratio of the brake thermal efficiency to the corresponding air standard
Efficiency. Therefore relative efficiency of engine is given by :
= Brake thermal efficiency
Air standard efficiency
Volumetric efficiency :
For four stroke engine, volumetric efficiency is ‘the ratio of volume of air admitted or
Air and petrol admitted the the engine cylinder during suction stroke at N.T.P. to the
volume swept by the piston during the stroke’.
=
Va
Vs
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10. MOTORING TEST
1. In this the ignition of petrol engine or fuel injection of
diesel engine is removed.
2. The engine is run by external motor of which the rated
power is known.
3. The power given by external motor to drive engine at
rated speed is the frictional power of engine.
4. Such test are carried at as max. operating temp.
possible.
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11. MORSE TEST
Purpose:- To measure frictional power of
multicylinder I.C. Engine
Actual working:-
First the engine is allow to run at const. speed and B.P. of engine is
measured by dynamometer when all cylinders are working.
(I1+I2+I3+I4)=(BP)engine –(F1+F2+F3+F4) …………………………(1)
Where
I1= indicated power developed by cylinder 1
I2 = indicated power developed by cylinder 2
I3 = indicated power developed by cylinder 3
I4 = indicated power developed by cylinder 4
F1=Frictional power of cylinder 1
F2=Frictional power of cylinder 2
F3=Frictional power of cylinder 3
F4=Frictional power of cylinder 4
( B.P.)engine= brake power of engine when all cylinders are
working
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12. Apparatus Required :
1. Multi cylinder petrol engine with ignition cut off arrangement
2. Loading arrangements
3. Tachometer
1, For slow speed engine the indicated power is directly calculated from
the indicator diagram.
2. But in modern high speed engines , it is difficult to obtain accurate
indicator diagram due to inertia forces , and therefore , this method
cannot be applied.
3. In such cases the Morse test can be used to measure the indicated
power and mechanical efficiency of multi cylinder engines.
The engines test is carried out as follows:-
Theory and Description :
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13. 1. The engine is run at maximum load at certain speed .
2. The B.P is then measured when all cylinders are working .
3. Then one cylinder is made in operative by cutting off the ignition to
that cylinder .
4. As a result of this the speed of the engine will decrease . Therefore
the load on the engine is reduced so that the engine speed is restored
to its initial value.
5. The assumption made on the test is that frictional power is depends
on the speed and not upon the load on the engine .
Observation and Tabulation :
(1) Brake power B.P =........... KW
(2) Rated Speed N =...........Rpm
(3) Type of loading : =...........
(4) Radius of brake drum : R =........... ‘m’
(5) Radius of Rope r = =........... ‘m’
(6) Number of cylinders = 4 13
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14. Sr.No Conditions Loading Speed
rpm
B.P.
In kW
W1 in
kg
W2 in
kg
W1 –
W2
Net load
W in N
1 All cylinders are working
2 1st cylinder was cut and
other are working
3 2nd cylinder was cut and
other are working
4 3rd cylinder was cut and
other are working
5 4th cylinder was cut and
other are working
Observation table:-
Note : The speed should be same for all readings
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15. (I2+I3+I4)=(BP)engine –(F1+F2+F3+F4) ……………………(2)
(I1+I3+I4)=(BP)engine –(F1+F2+F3+F4) ……………………(3)
(I1+I2+I4)=(BP)engine –(F1+F2+F3+F4) ……………………(4)
(I1+I2+I3+)=(BP)engine –(F1+F2+F3+F4)……………………(5)
Now subtract equation (2) from (1), we get
I1= (BP)engine – (BP)2,3,4
Now subtract equation (3) from (1), we get
I2= (BP)engine – (BP)1,3,4
Now subtract equation (4) from (1), we get
I3= (BP)engine – (BP)1,2,4
Now subtract equation (5) from (1), we get
I4= (BP)engine – (BP)1,2,3
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17. B.S.F.C.:-
1. Full form is Brake Specific Fuel Consumption.
2. It is weight of fuel required to develop 1KW of brake power for a period of
one hour.
3. It is inversely proportional to brake thermal efficiency.
fuel consumption in kg/Hr
B.S.F.C.= -----------------------------------
brake power in kW
Unit-kg/kW.hr 17
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18. CATALYTIC CONVERTOR
1. Catalytic convertors are widely used in car all over the world
.
2. It is a cylindrical canister placed between exhaust manifold
and silencer.
3. It contains plastic pallets coated with the catalyst .
4. They are designed for the oxidation of pollutant gases
escaping after primary combustion in the engine , within the
exhaust system.
5. The simplest type of catalytic converter is shown in fig.
6. The two basic types of catalytic convertor used in car are :
TWO WAY CATALYTIC CONVERTER
THREE WAY CATALYTIC CONVERTER
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19. 1.Two Way Catalytic Converter
• A converter is filled with a monolithic substrate coated with small
amount of
• platinum and Palladium.
• Through catalytic action of chemical change converts carbon mono
oxide (CO)
• and hydrocarbons (CH) into carbon dioxide and water. Such a
converter is called ‘TWO WAY CATALYTIC CONVERTER’.
2.Three Way Catalytic Converter
• It is installed on cars to check pollution . Such a converter uses thin
coating of platinum, palladium and rhodium over a support metal (
generally alumina ) and acts on all three.
• major constituents of exhaust gas pollution i.e. hydrocarbons , carbon
monoxide and oxides of nitrogen, oxidizing these to water, carbon
dioxide and free hydrogen and nitrogen respectively.
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20. Operating Stages Of Three Way Catalytic
Converter
1. The first stage uses rhodium to reduce the NOx in the exhaust into
nitrogen and oxygen.
2. In the second stage converter platinum or palladium acts as oxidation
catalyst to change HC and CO into harmless water and CO2 .
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21. Advantages of Catalytic Converter:
1. No regular maintenance is required.
2. It may be replaced at about 80000km or more.
3. The engine emission HC, CO, NOx are removed from exhaust
gas by oxidation.
Limitations Of Catalytic Converters :
1.Since lead destroys catalytic activity , the engine cannot use
leaded petrol.
2.Exhaust systems are hotter than normal as a result of exothermic
reaction in catalyst bed .
3.The emission of SO3 increases if fuel contains sulphur .
4.The use of equipments adds to the cost .
5.Periodic replacement of air filter of induction system is required
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22. POLLUTION CONTROL
Pollution in automobiles can be divided into 2 categories.
1. Non exhaust pollution:
2. Exhaust gas pollution
1. The automobile engines are mainly connected to pollution.
2. From the invention of engines, the problem of pollution is increased.
3. So it is necessary to study the pollution of automobiles engine and
effects of the pollution on the environment.
4. All the pollutants are due to composition of fuel with air, their
combustion and resultant chemical reaction of product of
consumption
POLLUTION OF I. C. ENGINES
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23. 1. NON EXHAUST POLLUTION
1. Primary due to evaporation of fuel hydrocarbons which is more
significant in petrol engines
2. Evaporation of fuel takes through vents in fuel tanks and carburetor
2. EXHAUST GAS POLLUTION
1. Major source of air pollution
2. Main constituents- nitric oxide(NO), NO2, CO, oxides of nitrogen,
organic compounds which are basically unbent
3. Hydrocarbon in exhaust gas may also condense around soot
particles to form particulate emissions
4. Compound of lead added petrol fuel also emit oxides of lead,
which is more significant in 2 stroke engines.
5. Traces of sulphur present results in sulphuric acid aerosol
6. The exhaust gas emission depend upon percentage of constituents
of air.
7. In petrol engine, combustion efficiency is 95-98% where as in diesel
engine, it is 98% or above
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24. POLLUTANTS IN EXHAUST GAS OF ENGINE
1.Carbon monoxide
2.Nitrogen oxide
3.Oxides of nitrogen
4.Unburned hydrocarbon
5.Particulates
6.Sulphates
7.Lead
8.scoot
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25. 1. CARBON MONOXIDE
1. it is colorless , toxic gas with acute effects
2. 0.3% CO in air can be lethal within 30 min., 300 PPM are
dangerous( 1PPM CO =1.25mg CO/m3)
2. Nitrogen Oxide
1. Colorless & rapidly forms reddish brown nitrogen dioxide in
presence of O2
2. Toxic substance with acute effects , which in concentration of
more than 1500 PPM causes sever irritation of respiratory
organs
3. Oxides Of Nitrogen
1. It is mixture of NO2 and N2O.
2. It is less dangerous in which high concentration and large exhaust
gas quantities are produced in upper power range of engine
3. 1PPM of NO=1.34mg/m3
4. 1PPM of NOx=2.5mg/m3
5. It causes several irritations of the mucous membranes of eye nose
and throat
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26. LEAD :-
1. It contains about 0.15gm Pb/ltr. Of petrol
2. Particulate emission rates are 100-150mg/km.
3. Size of particulate ranges from 0.2-2 micrometer diameter.
4. Emission rate is increased when exhaust flow rate is increased.
4. Particulates
Three classes of S.I. engines particulates:
Sulphates :-
1. It is in petrol gets oxidized toSO2.
2. The average automobile sulphate emission depend on fuel
sulphar content, operating conditions of engine.
Scoot
1. Its emissions results from incomplete combustion or
combustion of over rich mixtures
2. In proper engines, scoot in exhaust is not major problem.
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27. 5. UNBURNED HYDROCARBON
1. Sources are:
• The gas is forced in cavities in cylinder during compression and
combustion
• A thin layer of oil is present on cylinder wall, piston, or cylinder
head. This layer absorb the fuel HC before combustion and absorb
them after combustion
• Incomplete combustion of fuel in cylinder leads to form unburned
HC
2. The presence of HC is main cause of formation of photochemical
smog
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28. POLLUTANTS IN EXHAUST GAS OF DIESEL
ENGINE
Exhaust gases from diesel engine contains :
Nitrogen Oxides
1. The mechanism of NOx formation is same as in petrol engine.
2. The height of local peak temperature and sufficient oxygen gives
highest NOx concentration in diesel exhaust.
3. The NOx production is also affected by injection system and time.
Hydrocarbon
1. Diesel engine contains hydrocarbon compounds with higher
boiling points and higher molecular weight.
2. Fuel in diesel engine escape unburned due to-
i. The air fuel mixture becomes too lean to auto ignite at local point .
ii. The air fuel mixture becomes too rich to ignite or to support flame.
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29. Orsat Apparatus
It is a simple method of determination of exhaust gas analysis.
It is arranged for absorption of co2,o2and co
construction
It consist of :
Three double absorption flask for absorption of co2
co and o2
Each flask made up of two flasks joined together by a
glass tube.
Flask 1= NAOH: water
Flask 2 = Pyrogallic acid :water (1:3) and NAOH
or Potash: water (24:16)
Flask 3= CuO:HCL (1:20)
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30. WORKING
1. Filled the flask 1,2,3 with given chemicals
2. Open the three way cock open to atmosphere bottle is
raised up. Now the three way cock closed and bottle is
brought down.
3. In this way the previous gas remove from the apparatus is
removed.
4. Due to this it read eudiometer scale.
5. Three way cock is then opened an aspereter bottle is
lowered, thus engine exhaust is drawn in apparatus. After
drawing 100cc of sample three way cock is closed.
6. Cock connected to flask one is opened and aspereter bottle
is raised to push the sample.
7. This gas is drawn and again fill in the flask one. Due to this
co2 is absorbed and ediometer gives reading.
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32. EFFECTS OF POLLUTION ON ENVIRONMENT
AND HUMAN LIFE
1. The major air pollutant by petrol, diesel engines are
CO2,CO, HC, Nox,SO2 smoke and lead vapor.
2. Harmful to human , animal, and plant life
3. Pollutants causes lung & heart deterioration
CO:-
1. Atmospheric air contains 0.1-0.12ppm of Co.
2. 60% of CO is due to automobile engines.
3. Odor, colorless but toxic and blood poisoning
4. Reduces oxygen carrying capacity of blood
CO2:-
1. Temp. of earth increases 0.05oC/ year due to increase in CO2 by
0.75ppm/year.
2. Caused by deforestation, due to respiration of animals,
automobiles.
3. Causes respiratory disorder, suffocation
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33. NOx:-
1. Annual release of this is 5x 10raised to 7 tones due to auto.
Exhaust
2. Causes respiratory irritation, headache, bronchits, pulmonary,
corrosion of teeth to human body.
HC:-
1. Cause smoke which effects on reduced visibility, eye irritation,
damage of vegetation cracking of rubber products.
2. Some HC may induce cancer affect DNA and cell growth.
SO2:-
1. Toxic, corrosive gas.
2. Oxidizes to SO3, which combine with water to form sulphuric
acid aerosols.
3. It is corrosive and can harm human respiratory system and
plants, animals.
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35. Cubic
Capacity(cm3)
Carbon
Monoxide(gm/k
m)
HC+ NOx
(gm/km)
<1400 8.68 3.00
>1400<2000 11.20 3.84
>2000 12.40 4.36
Pollution Control Norms
Mass Emission Standards For Petrol Vehicles:-
Passenger Car
Carbon
MoNOxide(gm/km)
HC+NOx(GM/KM)
6.75 5.40
Three Wheelers(All Categories)
Carbon
MoNOxide(gm/km)
HC+NOx(GM/KM)
4.50 3.60
Two Wheelers(All Categories)
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37. Pollutants In Exhaust Gas Of Petrol
Engine
Exhaust gas
constituents
At idle At part load
Mean engine
speed and mean
load
At full load
Max. engine
speed & max.
load
Carbon
moNOxide
Volume %
2.00 to 4.50 0.20 to 1.00 2 to 5
Hydrocarbons
Volume %
1.01 to 0.05 0.01 to 0.02 0.01 to 0.03
Oxides of nitrogen
Volume %
0.005 to 0.03 0.25 to 0.35 0.15 to 0.45
Carbon dioxide
Volume %
10.00 to 13.00 13.50 to 14 11 to 13
Hydrogen
Volume %
1.5 0.50 0.10 to 0.50
Water vapour
Volume %
11.00 9 to 11 10 to 11
Lead compound
Mg/m3
50.00 40 50
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38. PERCENTAGE OF EXHAUST GAS
CONSTITUENTS IN DIESEL ENGINE
Exhaust gas
constituents
At idle At part load
Mean engine
speed and
mean load
At full load
Max. engine
speed & max.
load
Carbon
monoxide
Volume %
0.01 TO 0.045 0.01 TO 0.06 0.035 TO 0.20
Hydrocarbons
Volume %
0.005 TO 0.06 0.01 TO 0.035 0.02 TO 0.06
Oxides of
nitrogen
Volume %
0.005 TO
0.025
0.025 TO 0.08 0.06 TO 0.15
Carbon
dioxide
Volume %
3.50 6.50 12.00
Water vapour
Volume %
3.00 4.01 11.00 38
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