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NATIONAL INSTITUTE OF NATIONAL INSTITUTE OF TECHNICAL TEACHERS TECHNICAL TEACHERS TRAINING AND RESEARCH TRAINING AND RESEARCH CHANDIGARH CHANDIGARH
112/20/14
Prof. (Dr.) MP PooniaDirector, NITTTR
Chandigarh (India)
Fuel technology
Combustion technology
Aftertreatment technology
Fuel system technology
Better understanding of combustion
Alternate Fuels (Biodiesel)Low
sulfur
PM trap
Rate controlHigh pressure Multi-injection
EGR technology
Others
Control technology
Technology Pathway
Emission norms for passenger cars ( Petrol)
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Norms CO( g/km) HC+ NOx)(g/km)
1991Norms 14.3-27.1 2.0(Only HC)
1996 Norms 8.68-12.40 3.00-4.36
1998Norms 4.34-6.20 1.50-2.18
stage2000 norms
2.72 0.97
Bharat stage-II 2.2 0.5
Bharat Stage-III 2.3 0.35(combined)
Bharat Stage-IV 1.0 0.18(combined)
Emission norms for Heavy diesel vehicles:
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Norms CO (g/kwhr)
HC(g/kwhr)
Nox(g/kwhr)
PM(g/kwhr)
1991 Norms 14 3.5 18 -
1996 Norms 11.2 2.4 14.4 -
stage 2000 Norms 4.5 1.1 8.0 0.36
Bharat stage-II 4.0 1.1 7.0 0.15
Bharat Stage-III 2.1 1.6 5.0 0.10
Bharat Stage-IV 1.5 0.96 3.5 0.02
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• Volumetric efficiency (ηv) = (mass of air actually drawn into cylinder) / (mass of air that ideally could be drawn into cylinder)
where ρair is at ambient = Pambient/RTambient and R - 287 J/kgK for air• Volumetric efficiency indicates how well the engine “breathes” -
what lowers ηv below 100%?– Pressure drops in intake system (e.g. throttling) & intake
valves– Temperature rise due to heating of air– Volume occupied by fuel– Non-ideal valve timing– “Choking” (air flow reaching speed of sound) in part of intake
system having smallest area
Volumetric Efficiency
nNVdairv /
(measured) mair
ρη
≡
Turbochargers & Superchargers
• Superchargers: mechanically driven from engine crankshaft
• Turbochargers: driven by waste exhaust gases increased air mass improves the engine's thermal efficiency (fuel economy) and emissions performance,
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• Engine performance is specified in both in terms of power and engine torque - which is more important?– Wheel torque = engine torque x gear ratio
tells you whether you can climb the hill
Power and Torque
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– Power tells you how fast you can climb the hill– Torque can be increased by transmission (e.g.
2:1 gear ratio ideally multiplies torque by 2) Power can’t be increased by transmission; in fact because of friction and other losses, power will decrease in transmission
– Power tells how fast you can accelerate or how fast you can climb a hill, but power to torque ratio ~ N tells you what gear ratios you’ll need to do the job
There is a maximum in the brake power versus engine speed called the ratedbrake power.
At higher speeds brake power decreases as friction power becomes significant compared to the indicated power There is a maximum in the torque versus speed called maximum brake torque (MBT).
Brake torque drops off: • at lower speeds do to heat losses • at higher speeds it becomes more difficult to ingest a full charge of air.
Max brake torque
1 kW = 1.341 hp
Rated brake power
Power and Torque versus Engine Speed
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Mathematically different from the British unit1 Power PS = 0.986 BhpPferde Stärke = Horse Strength (German)Power (PS@rpm)
67@5500 65@6200
Torque (Nm@rpm)
99@2800 84@3500
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Convert from these to watts (W)
multiply by
erg's per second (erg/s) 0.000 000 1
horsepower (electric) 746
horsepower (hp)(metric,DIN,PS)
735.4988
horsepower (hp)(U.K.) 745.7
kilowatt (kW) 1000
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Engine
Engine Type/Model 1.4L SOHC PetrolDisplacement cc 1405Power (PS@rpm) 60PS @4500rpmTorque (Nm@rpm) 105Nm @2500rpmValve Mechanism SOHCBore (mm) 75Stroke (mm) 95Compression Ratio 9:1
No of Cylinders (cylinder) 4
Cylinder Configuration Inline
Valves per Cylinder (valve) 2
Fuel Type PetrolFuel System Carburettor mechanical fuel pump
Engine Torque and Power
Torque is measured using a dynamometer.
Load cell
Force FStatorRotor
b
N
The torque exerted by the engine is: T = F b with units: J
The power Wdot delivered by the engine turning at a speed N and absorbed by the dynamometer is:
Wdot = ω T = (2π N) T w/units: (rad/rev)(rev/s)(J) = Watt
Note: ω is the shaft angular velocity with units: rad/s
Indicated WorkGiven the cylinder pressure data over the operating cycle of the engine one can calculate the work done by the gas on the piston.
The indicated work per cycle is ∫= PdVWi
CompressionW<0
PowerW>0
IntakeW>0
ExhaustW<0
WA > 0
WB < 0
I.C. ENGINE TESTING
Measurement of Air Supply of an I.C. Engine:
Measurement of Airby Air Box Method.
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