UNIT IIIUNIT - IIIEngine Emissions & Their Control

Introduction Gl b l i Global warming

Acid rain

Smog

odour

Respiratory and other health hazards

Ozone - lung tissues & functionsOzone - lung tissues & functions

PM - respiratory problems, Visibility, Irritations

CO O delivery to bloodCO - O2 delivery to blood

Lead - children Visibility

NO l & i t f tiNOx - lungs & respiratory functions

SOx - Acid rain

The Internal Combustion Engine and Atmospheric Pollution

Type of Pollution Principal Sources Relevance of the I.C. Engineype o o u o c p Sou ces e ev ce o e .C. g e

Lead Anti-knock compounds A (for the SI Engine)

A id R i S lf di id B (f th CI E i )Acid Rain Sulfur dioxide B (for the CI Engine)Oxides of nitrogen AUnburned hydrocarbons A (for the SI Engine)Carbon monoxide A (for the SI Engine)

Global warming CFCs B (for car with A/c)(or else not involved)

Carbon dioxide B (may be even A)Methane B (may be A if CNG used)

Photochemical smog Carbon monoxide A (for the SI Engine)Unburned hydrocarbons A (for the SI Engine)Sulfur dioxide B (for the CI Engine)Oxides of nitrogen A

Ozone depletion CFCs B (for car with A/c)(or else not involved)

Unburned hydrocarbons A (for the SI Engine)Oxides of nitrogen Ag

A: Major contributorB: Secondary influence

Engine Emissions

Engine Exhaust Emissions Unburned Hydrocarbons (HC)

Oxides of Carbon ( CO, CO2)

Oxides of Nitrogen ( NO, NO2)

Oxides of Sulphur (SO2, SO3) Oxides of Sulphur (SO2, SO3)

Particulates (PM)

Soot & Smoke

Aldehydes

Lead

N E h E i iNon – Exhaust Emissions Unburned HC from fuel tank

Crankcase blowby Crankcase blowby

Vehicular Emissions

Unburned HC Formation Irritate the mucous membranes Irritate the mucous membranes Operating conditions 1000- 2000 rpm It rise rapidly as the mixture becomes richer than stiochiometric

mixturemixture Incomplete combustion Air – fuel ratio

I i i Improper mixing Flame quenching

Factors which lead to incomplete flame propagation Poor carburetion and mixture preparation Poor ignition system Scavenging problem due to improper valve overlapg g p p p p Poor swirl and turbulence Excess exhaust residual gas within the cylinderExhaust gas recirculation not properly controlledExhaust gas recirculation not properly controlled

Leakage past the exhaust valve

Lubricating Oil layer Lubricating Oil layer

The presence of lubricating oil in the fuel

Deposits on combustion chambers walls

Vehicles run over several thousand kms

It’s rate depends on fuel and operating condition

Ol fi d i d d h f b ildOlefins and aromatic compounds tends to have faster buildup

Valve overlap

Evaporative emissions Evaporative emissions

Crankcase blowby

Crevice Volumes l d h f f h b i Narrow volumes present around the surface of the combustion

chamber

High surface to volume into which flame will not propagateg p p g

They are present between the piston crown, piston rings and cylinder

liner

Along the gasket joints between cylinder head and blockAlong the gasket joints between cylinder head and block

Along the seats of the intake and exhaust valves,

space around the plug center electrode and between spark plug

threads.

Normalized A/F ratio, = (A/F) actual / (A/F) stoichiometric

Equivalence ratio: = (A/F)stoichiometric / (A/F) actual

Fig. Emissions for diesel engine

CO formation Colourless gas of about the same density as air

Poisonous gas, which when inhaled replaces the oxygen in the blood stream

Slowdown physical and mental activity

Headache Headache

Large concentration can lead to death

Due to dissociation processLoss in chemical energy

Incomplete combustion

It increases during idling and lowest during acceleration It increases during idling and lowest during acceleration

Rich mixture

Poor mixing

CO value does not drop to zero value when the mixture is chemically correct and leaner

Combination of cycle to cycle and cylinder to cylinder air-fuel mixture maldistribution

NOx FormationPhotochemical smogPhotochemical smogPrincipal source is oxidation of atmospheric nitrogenDissociation of the molecular oxygen and nitrogen at the peak

combustion temperaturescombustion temperaturesTemperature range of 1100 ºcHigh temperature will promote the formation of NO by speeding up the

formation reactionsformation reactions Maximum level – 10 % above the stoichiometric Too much lean mixture – reduce peak temperatureNitrogen present in the fuel O + N2 = NO + N Equivalence ratio N+ O2 = NO + O Advanced spark timing N + OH = NO+ H NO+ H2O = NO2+ H2 NO + O2 = NO2 +O (Zeldovich Mechanism) NO O2 NO2 O (Zeldovich Mechanism)

Photochemical smogPhotochemical chemical reaction of automobile e haust and Photochemical chemical reaction of automobile exhaust and

atmospheric air in the presence of sunlight

HC + NO li ht SHC + NOx sunlight Smog

Sulphur(SOx)Fuel specification( Limit 50ppm or mg/kg)Fuel specification( Limit 50ppm or mg/kg)Acid rain problemAt high temperature

H + S H SH2+ S H2SO2+ S SO2

2SO2 + O2 2SO3

SO3+ H2O H2SO4

SO2+ H2 O H2SO3

LeadG li dditi Gasoline additive It hardens the surfaces of the combustion chamberLimit - 0.05 g/l

AldehydesMainly available in alcohol Mainly available in alcohol Product of incomplete combustionAn eye and respiratory irritant

N E h E i iNon – Exhaust EmissionEvaporative emission 15 to 25 % of the total HC emission from a

gasoline engine Crank case blowby – 20 – 30 % of the total HC

Evaporative EmissionsFuel tank lossesCarburettor losses

Fuel tank losses Fuel volatilityFuel volatilityThe ambient temperatureAmount of fuel in the tank k d i l iTank design, locationRefueling losses

Carburettor lossesRunning losses Losses through vent during operation

These losses are significant only during hot condition when the ese osses a e s g ca t o y u g ot co t o w e t e vehicle is in operation

Parking losses

Evaporative emissions increase significantly if the fuel volatilityif the fuel volatility increases”

Dirunal Emissions Take place from fuel tanks and carburetor float bowls

(in engines fitted with carburetors) of parked vehicles.

It draws in air at night as it cools down g

Expels air and gasoline vapour as it heats up during the day.

These could be up to 50g per day on hot days.

Hot Soak Emissions This occurs after an engine is shut down.

The residual thermal energy of the engine heats upThe residual thermal energy of the engine heats up

The fuel system leading to release of fuel vapours.

Running Losses Gasoline vapours are expelled from the tank (or float bowl)

when the car is driven and the fuel tank becomes hot.

This can be high if the ambient temperature is high.This can be high if the ambient temperature is high.

Crankcase blow by Leakage past the piston piston rings from the cylinder to the crankcaseLeakage past the piston, piston rings from the cylinder to the crankcase• Blow by gases are produced in the crankcase during the normal

combustion processPi t bl b i ith i d d i ti l th • Piston blowby increases with engine speed and in particular as the piston rings and cylinder bore wears

SI Engine Emissions Control Main approachesEngine design modification & Operating parametersEngine design modification & Operating parametersTreatment of exhaust gas Fuel modification

Engine modifications Engine modificationsCombustion chamber configuration Reduce surface to volume area Reduce space around the piston ringsg Reduce top land distance Avoid flame quenching zones

Lower compression ratioR h hi Resuces the quenching area

Also reduces NOx emissions Affect the thermal efficiency

Modified induction system Modified induction system Supply of air-fuel ratio for all cylinders under all operating conditions of load

and speed Multi choke carburettors or MPFI system

Ignition timingProper ignition timing

Affect HC and NOx formation

Required spark advance during cruising and retard the same for idling running

Also affect the power output

Valve overlap

Sh ld b d d Should be reduced

Variable Valve Timing – control of scheduling of valve timing events

Use of leaner air-fuel ratios Use of leaner air fuel ratios

Proper modification required to provide lean and stable air-fuel mixtures during idling and cruise operation

Electronic Fuel injection system

Coolant temperature

HC hi h HC – high

NOX – low

Fuel modification Unleaded Petrol

0.05% sulphur in petrol

0.05% sulphur diesel

Using reformulated fuels Using reformulated fuels

Oxygenated gasoline in winter season

Low volatility in summer –To reduce HC emission

Evaporation Loss control deviceControl all evaporative emissions by capturing the vapours and p y p g p

recirculation them at the appropriate timesAdsorbent chamber Charcoal bed or formed polyurethaneC a coa be o o e po yu et a e Adsorbs the vapour Canister

The purge control valvePurging - process by which the gasoline vapours are removed

Activated Carbon

Atmosphere vent

Inlet manifold

Fuel tankFuel tank vent

Crankcase ventilations

Phenomenon of leakage past the piston and piston ringsPhenomenon of leakage past the piston and piston rings

from the cylinder to the crank case

20% of the total HC emission from the engine 20% of the total HC emission from the engine

Rings are worn out

Recirculation of the vapours back into the intake air cleanerRecirculation of the vapours back into the intake air cleaner

Closed or open crankcase ventilation

S t l d d li ht System placed under slight vacuum

Positive crankcase ventilation

When the acuum is high blo b is lessWhen the vacuum is high - blowby is less

At wide opening throttle , the air flow gets unrestricted but flow rate is metered by the valve opening

P C V V a lv eP C V V a lv e•A spring or vacuumIn le t M an ifo ldIn le t M an ifo ldIn le t M an ifo ld C ra n k c a s eC ra n k c a s eC ra n k c a s e

P C V V a lv eP C V V a lv e•A spring or vacuum regulated valve (PCV valve) or fixed orifice )meters the flow of air and blow-by gases into the intake manifold

Exhaust Treatment MethodsAfter burners Sustain the high temperature within the system during rich

operating conditions

High heat losses over a large area High heat losses over a large area

Catalytic ConvertersThree way catalytic converter

CO, HC and NOx reduction

CO and HC can be oxidized to CO2 and H2O in the exhaust systems

Its quality degraded by heat life contaminants Its quality degraded by heat, life , contaminants

Stainless steel container

Inside the container – Porous ceramic structure

Ceramic honeycomb or matrix structure- also called monolith

A bed of spherical ceramic pellets

Volume of the ceramic structure is about half of the displacement Volume of the ceramic structure is about half of the displacement volume

To reduce HC and CO emission

Located very near to the exhaust manifold – No fall in the temperature of exhaust

NOx emission is not affected by the air injection

Catalytic materials

Al i O id B i i lAluminum Oxide – Base ceramic material

Withstand high temperature

Low thermal expansion Low thermal expansion

Platinum & Palladium – CO& HC emissions

Rhodium – NOx Rhodium NOx

Efficiency of the TWC depends on temperature

400ºC or above 400 C or above

98-99% co, 95% NOx and more than 95% HC

Proper equivalence ratio to get high converter efficiencyp q g g y

Engine malfunctions can cause poor efficiency and overheating of

converters

b k Above 2,00,000km

Thermal degradation range – 500 – 900ºC

Impurities like lead, sulphur, Zinc and Phosphorous Impurities like lead, sulphur, Zinc and Phosphorous

Not efficient during cold condition Light-off temperatureg p The temperature at which the catalytic converter becomes 50%

efficient. It is approximately 270oC for oxidation of HC and about 220oC for oxidation of CO.

By locating the converter close to the engine By employing preheating By using flame heating By using flame heating

Emission Norms and Driving Cycles

OVERVIEW OF THE EMISSION NORMS IN INDIA

• 1991 - Idle CO Limits for Gasoline Vehicles and Free Acceleration Smoke for Diesel 1991 Idle CO Limits for Gasoline Vehicles and Free Acceleration Smoke for Diesel Vehicles, Mass Emission Norms for Gasoline Vehicles.

1992 - Mass Emission Norms for Diesel Vehicles.

1996 - Revision of Mass Emission Norms for Gasoline and Diesel Vehicles, mandatory fitment of Catalytic Converter for Cars in Metros on Unleaded Gasoline.

1998 - Cold Start Norms Introduced.

2000 - India 2000 (Eq. to Euro I) Norms, Modified IDC (Indian Driving Cycle), Bharat Stage II Norms for Delhi.

2001 - Bharat Stage II (Eq. to Euro II) Norms for All Metros, Emission Norms for CNG & LPG Vehicles.

2003 - Bharat Stage II (Eq. to Euro II) Norms for 11 major cities.

2005 - From 1st April Bharat Stage III (Eq. to Euro III) Norms for 11 major cities.

2010 - Bharat Stage III Emission Norms for 4-wheelers for entire country whereas Bharat Stage - IV (Eq. to Euro IV) for 11 major cities.

E-III (Country)

E-II (Country)

E III (Country)

E-VI (11 Cities)2010

E-II (11 Cities)2005Norms Cities of

implementationEffective Date

91 emission norms

Throughout the nation

1.4.91/92

Emission norms

2nd set norms notified

2000/01

1996

96 emission norms

Throughout the nation

1.4.96

Cat Con Norms(Cars)

45 cities 1.10.98

I di t 00 Th h t th 1 4 2000

1st of norms notified

Emission norms

for cat con veh1995

India stage 00 norms

Throughout the nation

1.4.2000

BS II 11 citiesThroughout the nation

2000-20031.4.2005

1990 BS III 11 citiesThroughout the nation

1.4.20051.4.2010

BS IV -11 cities 1.4.2010Throughout the nation

-

Indian Emission Standards (4-Wheel Vehicles)

Standard Reference Date Region

India 2000 Euro 1 2000 NationwideIndia 2000 Euro 1 2000 Nationwide

Bharat Stage II Euro 2

2001 NCR*, Mumbai, Kolkata, Chennai

2003.04 NCR*, 10 Cities†Bharat Stage II Euro 2 2003.04 NCR , 10 Cities†

2005.04 Nationwide

Bh t St III E 32005.04 NCR*, 10 Cities†

Bharat Stage III Euro 32010.04 Nationwide

Bharat Stage IV Euro 4 2010.04 NCR*, 10 Cities†

*National Capital Region (Delhi)† Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Ahmedabad, Pune, Surat Kanpur and AgraSurat, Kanpur and Agra

Petrol specification

Vehicular Technological Upgradations Required

2/3 Wheelers ?Secondary air injection Fuel injection

Category of Engine Bharat Stage II Bharat Stage III Bharat Stage IV

2- Stroke SI Engines

jCatalytic converterCNG / LPG

Catalytic converter

2/3 Wheelers

4- Stroke SI

Fuel injection + catalytic converter

4-Stroke designSecondary air injection (specific power

Carburetor + secondary air injection + catalytic converter4 Stroke SI

EnginesLean burn

( p pbased)

Directi li dFuel injection Fuel injection +

t l ti t4 Wheelers

4- Stroke SI Engines

in-cylinderinjectioncatalyticconverterLean burn

Fuel injectionCatalytic converterFixed EGRCNG / LPG

catalytic converterVariable EGRVariable valve timingMulti valveCNG / LPGEngines

Vehicular Technological Upgradations Required

NOx TrapParticulate trap

TurbochargingInter cooling (based

TC & inter coolingMulti valve

Category of Engine Bharat Stage II Bharat Stage III? Bharat Stage IV?

Diesel Engines

pCommon railinjectionInjectionpressure > 1600bar

g (on specific power)Moderate swirlInjection pressure >800 barRotary pump

Low swirlInjection pressure >1200 barUnit injector /common rail injectionDiesel Engines bar

On-boarddiagnostic systemVGTCooled EGR

Rotary pumpEGR (need based)Conversion to CNG/ LPG

common rail injectionRotary pump andpilot injection rateshapingVariable geometryturbocharger (VGT)OxycatEGR (hot/cooled)Electronic injectioncontrol

Sulphur content in diesel < 50 ppm<15 ppm for NOxcontrolSulphur content in

diesel < 500 ppm

Sulphur content indiesel <300 ppm

15 ppm for NOxtrap

pp

Petrol Vehicles(4- Wheelers)

• Onboard Diagnostic system• Low sulphur gasoline• Low sulphur gasoline • MPFI/GDI • Lean Burn operation (A/F ratio from 16:1 to• Lean Burn operation (A/F ratio from 16:1 to

22:1)• Variable Valve Actuation – To control charge• Variable Valve Actuation – To control charge• PCV/ Charcoal canister system

Diesel VehiclesOnboard Diagnostics System• Onboard Diagnostics System

• Unit Injector – 2500 barCRDI 1600 b• CRDI – 1600 bar

• Homogeneous Charge Compression Ignition • Fuel cell• CNG/ HANG• Particulate Trap/ Diesel Oxidation Catalyst

2 Wheelers• Fuel injection(GDI or Port oe throttle body)• Electric motor cyclesy• Catalytic converter• Evaporative emission control device• Electronic ignition • EFI

C b ti h b ti i ti• Combustion chamber optimization

Diesel Engine /Vehicle Emission testing procedureprocedure

• 3 wheelers, passenger cars, Multi utility vehicles (with GVW < 3 5 ton) : Vehiclevehicles (with GVW < 3.5 ton) : Vehicle testing on Chassis Dynamometer

• Diesel vehicles with GVW > 3.5 ton : Engine testing on Engine Dynamometer

Equipments used for Diesel Engine Testing on Engine Dynamometeron Engine Dynamometer

• Engine Dynamometer

• a) Eddy current typea) Eddy current type

• b) Transient Dynamometer (AC/DC)

• Throttle actuator• Throttle actuator

• Fuel consumption meter

• Ai ti t• Air consumption meter

• Fuel conditioning unit

E i i k i di i i i• Engine intake air conditioning unit

• Engine cooling water temperature controlling unit

• Intercooler for turbocharged + after cooled engines

Equipments used for Diesel Engine Testing on Engine Dynamometeron Engine Dynamometer

• Exhaust gas analyzers• a) Diluted measurement : • CO CO THC NOx CH• CO,CO2,THC,NOx,CH4

• b) Raw measurement : • CO,CO2,THC,NOx,O2

P• Pressure sensors :• Intake air pressure• Exhaust back pressure

I k d i• Intake depression• Boost pressure (Turbocharged engines)• Oil pressure

T• Temperature sensors :• Intake air temperature• Fuel temperature• Oil temperature• Boost temperature• Exhaust temperature

Exhaust gas measurement principles

• CO, CO2 : Non Dispersive Infra Red (NDIR) method

• THC : Flame Ionization Detection (FID) method

• NOx : ChemiLuminescent Detector (CLD), D VRNDUVR

• PM : Sampling Filters (with Dilution Tunnel)

Driving Cycles Standard Driving Pattern

Probable plot of the vehicle speed right from the start of the engine through its journey over a prescribed time

Pattern is described by means of a velocity time table Pattern is described by means of a velocity time table

It is a series of data points representing the speed of a vehicle versus time

To assess the performance of vehicle in various ways

Vehicles simulation

Constant volume sampling (CVS)p g ( )

Exhaust gas diluted by adding air which is supplied by blower and collected in separate bag

C t t ti f h t i (10 1) Constant proportion of exhaust gas: air (10:1)

Condensation of water vapour( Affect NOx emission)

Prevent the exhaust components (HC) reacts with otherp ( )

Driving cycle derived from driving behavior and real traffic conditions

Gear shifts

Braking

Idle Phases

Standstill periods

Types of Driving Cycles

Transient Driving cycles – constant speed changes on road conditions (FTP and some of European cycles)conditions (FTP and some of European cycles)

Model Cycles - Protracted periods at constant speeds

Transient Driving Cycle

Average emission performance per km drive

Integrate the total effects of the road infrastructure

Traffic pattern and driving culture

Group of driving cycle

European driving cyclep g y

US driving cycle

Japanese driving cycle

Indian Driving Cycle (IDC) - 1985 – followed for 2/3 wheelers

Modified Indian Driving cycle – Light & heavy duty vehicles

European Driving Cycle

ECE 15 – speed 50kmph, low loadp p ,

EUDC – Urban driving cycle

EUDCL – For suburban route (speed 90kmph)

ECE83 – New European driving cycle

US Driving Cycle

FTP 72 - Urban route FTP 72 - Urban route

FTP75 – Three phase (cold start+ transient+ hot starting)

LA 92

US 06 – High average speed

SC03 - A/C vehicles

i i lJapanese Driving Cycle

10 mode cycles

15 mode cycles 15 mode cycles

Typical Driving Cycle

EMISSION CYCLE130

100

110

120

130

60

70

80

90

EED

[KMPH]

30

40

50

60

SPE

E

0

10

20

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

SECONDSSECONDSEURO II BS II

European Driving Cycle New European Driving Cycle (NEDC) ECE15 simulates 4.052 km urban trip at an average speed of 18.7km/h and

at a max speed of 50 km/h EUDC simulates 6.955 km at an average speed of 62.6 km/h Max speed 120 km/h Max speed 120 km/h Idling period has been eliminated in New cycle Idling period 40 s

Fig. ECE15 driving cycle

Fig. EUDC driving cycle

Indian Driving Cycles Similar to ECE15+EUDC except the maximum speed is 90km/h Duration of one cycle = 108s Distance per cycle = 658km Total distance = 3948km No of cycles = 6 Total distance = 3948km No of cycles = 6 Avg speed = 25.7 km/h Max speed -= 42 km/h

Indian Driving Cycleg y

40

50

20

30

40

ED(k

m/h

r)

0

10

20

SPE

00 20 40 60 80 100

TIME(sec)

CruiseTime Distance

Avg. Speed Max. Speed

Max. accel. Max Decel

Idle time ratio

Accel. Time ratio

Decel time ratio

Cruise time ratio

sec km km/h km/h m/s2 m/s3 % % % %IDC 648 3 948 21 93 42 0 65 0 63 14 81 38 89 34 26 12 04(6 Cycles) 648 3.948 21.93 42 0.65 0.63 14.81 38.89 34.26 12.04

Indian Driving Cycle for 4 Wheelers

100Part 1: 780 sec

Part 2: 400 sec

60

80

km/h

)

One Cycle of 195 sec

Part 1: 780 sec 400 sec

40

60

Spee

d (k

Max Speed

0

20

S Max Speed 90 kph

00 500 1000

Time (sec)

US Driving Cycles Vehicle is fitted in a room temperature of 20 to 30 ºC It simulates 17.7 km at an average speed of 34.1 km/h Duration 1874 s Transient test cycle with highly dynamic nature Transient test cycle with highly dynamic nature

FTP US06 High speed and high

acceleration driving behaviour

FTP SC03 Engine load and emissions g

Rapid speed fluctuations Average speed 77.9km/h

associated with air conditioned vehicles

Japan Driving Cycles 10 Mode cycles – Urban conditions 10 Mode cycles Urban conditions One segment covers a distance of 0.664 km at an average speed of

17.7km/h Max speed 40km Max speed 40km Cycle begins with a 15 minutes warm up

Diesel Engine Emissions & Their Control

Diesel Engine EmissionsCarbon Monoxide (CO)Carbon Monoxide (CO)Unburned Hydrocarbons (HC)Oxides of Nitrogen (NOx)

P ti l t M tt (PM)Particulate Matter (PM)Smoke

HC Emissions1/5 of HC emissions of SI enginesOver all fuel – air lean equivalence ratioNon-homogeneity of fuel- air mixtureNon homogeneity of fuel air mixtureSome local spots in the combustion chamberSome fuel particles in fuel rich zones never react due to lack of

oxygenoxygenDribble in fuel injectorCrevice volume

ll d bWall deposit absorptionOil film adsorption

Particulate Matter (PM)Any matter in the exhaust gases that can be trapped on sampling

filter medium at particular temperature at 52ºC

Solid carbon soot particles that are generated in the fuel rich zones

within the cylinder during controlled combustion phase

S i l l f lid b h Soot particles are clusters of solid carbon spheres

Diameters from 9nm to 90 nm

The spheres are solid carbon with HC and traces of other

components adsorbed on the surface

Large expansion occurs during power stroke

The remaining high boiling components found in the fuel and

lubricating oil condenses on the surface of the solid carbon

t ti lsoot particles

Adsorbed hydrocarbons: Soluble organic fraction (SOF)

Si ifi f i f SOF f l b i i Significant fraction of SOF may come from lubricating

oil(25%)

S lf i th f l f lf i id hi h i l t l d Sulfur in the fuel forms sulfuric acid which is later sampled

as PM

Soot PhotomicrographsSoot Photomicrographs

Diesel smokeBl k k f t Black smoke : from soot

White, blue or gray smoke: condensed hydrocarbon droplets in the exhaust

Blue or gray generally due to vaporized lubricant White due to cold start

Emissions Control Technology - CI Ad n d t hn l in f l inj ti n t m Advanced technology in fuel injection system

Combustion chamber geometry

Two way catalyst – CO & HC

Diesel Oxidation Catalyst (DOC)

Particulates

Particulate Traps

Diesel Particulates Filter (DPF)

NOx Emissions

Additives into diesel fuel

Water injection

Emulsion Technology

Injection timing retardation Injection timing retardation

Simulatneous technology

Exhaust gas Recirculation (EGR)

S l ti C t l ti R d ti (SCR) Selective Catalytic Reduction (SCR)

Low temperature combsution

Advanced technology in fuel injection system Injection pressure upto 1800 bar – 2500 barj p p

Pilot injection - Reducing combustion noise – shorten the ignition delay

Post injection - Increase of temperature at the end of the combustion process, which favours oxidation of the soot formed during the firstprocess, which favours oxidation of the soot formed during the first stages of combustion process

Use of different additives Oxygenated additives: Ethanol/ dimethyl ether/methanol)

Cetane number improvers : EHN

Antioxidants (for biodiesel): NPAA, DPPD( ) ,

Drawbacks:

Very expensive

P d hi h CO HC d PM i i Produce higher CO, HC and PM emissions

Use of Emulsion Technology To introduce the water in the combustion chamberd

Emulsifying agent or surfactant: To reduce the surface tension between oil and water

Drawbacks:Drawbacks:

Higher viscosity and density of water significantly affect the performance

Inherently unstable and prone to phase seperation

Cold start issues

Exhaust Gas Recirculation (EGR)Most effective technique for both SI and CI enginesMost effective technique for both SI and CI enginesTo dilute air- fuel mixture with non reacting gasAdding air changes air-fuel ratio and combustion characteristicsLower the flame temperatureGases with larger specific heats

EGR IN SI ENGINESEGR IN SI ENGINES5 to 15 percent of the exhaust gas is routed back to the intake as

EGR

Maximum quantity is limited by the requirement of the mixture to sustain a contiguous flame front during the combustion event

Reduced heat transfer to combustion chamber surfaceReduced heat transfer to combustion chamber surfaceReduced chemical dissociationNot employed at WOT and idling condition

EGR IN DIESEL ENGINESMaximum possible flow 30 % of total intakeMaximum possible flow – 30 % of total intakeFlow rate can be controlled by Engine Management SystemThermal efficiency decrease Increase the PM emission In modern diesel engines EGR gas is cooled through a heat

exchanger to allow the introduction of a greater mass ofexchanger to allow the introduction of a greater mass ofre circulated gas

External EGR - Piping a route from the exhaust manifold to the inlet manifold

Internal EGR - Trapping exhaust gas within the cylinder by not fully expelling it during the exhaust strokeexpelling it during the exhaust stroke

VGT arrangement

EGR cooler

Selective Catalyst Reduction(SCR) NOx reduction technique NOx reduction technique Conversion of NOx with the aid of catalyst into N2 and H2O Reduction agent : Urea, Anhydrous ammonia or aqueous ammonia Catalysts: Oxides of base metal such as Vanadium, Tungsten Titanium

oxide Vanadium, Tungsten- Less expensive and lack in durability, g p y Damage the Particulate Filter Zeolite – High thermal durability

O i 500 720 KOperating range - 500 to 720 K

4NH3 + 4NO + O2 -> 4N2 + 6H2O2NH + NO + NO > 2N + 3H O

For Urea

2NH3 + NO + NO2 -> 2N2 + 3H2O8NH3 + 6NO2 -> 7N2 + 12H2O

For Urea

Anhydrous Ammonia – Extremely toxic and difficult to safely store

Aqueous ammonia Safely to storeAqueous ammonia – Safely to store

Hydrolyzed to be used

Urea – Require conversion process to ammoniaUrea Require conversion process to ammonia

Technical problems with automotive SCR unitsR i f f t i tRemains free from contaminants

Correct materials of construction must be used for both storage and dispensingg p g

Ammonia slip – Release of unreacted ammoniaWhen catalyst temperatures are not in the optimal range

f h ifor the reactionWhen too much ammonia is injected into the processLow exhaust gas temperature during cold start conditionLow exhaust gas temperature during cold start condition

Selective Catalyst Reduction (SCR)

Particulate Trap Filter –like system often made of ceramic in the form of a monolith

or mat or made of metal wire mesh (cordierite or silicon carbide)

As traps catch the soot particles, they slowly fill up with particulates

This restricts exhaust gas flow and raises the back pressure of the g pengine

Higher back pressure causes engine runs hotter

Exhaust temperature increases p

Carbon soot ignition temperature – 550 to 650ºC

Regenerative trapWhen the pressure across the trap reaches theWhen the pressure across the trap reaches the

predetermined value, automatic flame igniters start the combustionCarbon soot ignition temperature – 550 to 650ºCElectric heaters or diesel flame nozzlesIf a catalyst material is installed in the traps theIf a catalyst material is installed in the traps, the

temperature needed to ignite the carbon soot is reduced to the 350 to 450ºC

DIESEL OXIDATION CATALYST(DOC)T W C t l t (TWC) Two Way Catalyst (TWC)

It is a device that uses a chemical process to breakdown pollutants in the exhaust stream into less harmful componentsp

Porous ceramic honeycomb – like structure that is coated with a material that catalyzes a chemical reaction to reduce a pollution

Soluble Organic Fractions (SOF) removal – 80 to 90%

PM reduction – 20 to 50 %

Unburned Hydrocarbon (HC) reduction – 50%

Carbon Monoxide reduction– 40%

Eff ti f th DOC i d ith Ult l lf di l(15 ) Effectiveness of the DOC increased with Ultra low sulfur diesel(15ppm)

At high exhaust temperature, catalyst can oxidize SO2 to form sulfate particulatesparticulates

Diesel Oxidation Catalyst (DOC)

St i l t l C i t Stainless steel Canister

Catalyst support or substratesubstrate

Ceramic or metallic honeycomb or wire mesh structure

Catalytic coating

Pl i Platinum

Palladium

No technology maintenance

Abilit t b d hi l / i t f l d ith ti l Ability to be used on vehicles/ equipment fueled with conventional diesel fuel

No operational issues, impact on vehicles/ equipment performance or No operational issues, impact on vehicles/ equipment performance or impacts on fuel consumption

2,00,000 km and can last 7 to 15 years

DOC may suffer when exposed to temperatures above 650ºC for prolonged period of time

S l h i l l t h h h l d d h Several chemical elements such as phosphourus , lead and heavy metals also damage some catalysts

The size of DOC need to be matched to engine displacement and The size of DOC need to be matched to engine displacement and exhaust system

UNIT - IVUNIT - IV

NATURAL GAS

IntroductionMixture of paraffinic hydrocarbonsMixture of paraffinic hydrocarbons

It occurs in gas fields and also in association with crude petroleum in oil fields

Found compressed in porous rock and shale formations sealed in rock strata underground

Raw gas contains mainly methane plus lesser amounts of ethane, propane, butane and pentane, negligible sulfur

Some carbon dioxide and nitrogen are present Some carbon dioxide and nitrogen are present.

The only gas occurring in natureTypical Compositionyp p

Methane – 60 to 90 % Ethane - 3 to 30 % Propane 1 to 3% Propane - 1 to 3%

Properties C l l d d l Colourless and odourless gas

Commercial odorant is added

Lighter than air with specific Lighter than air with specific gravity 0.6 to 0.8

Clean burning fuel

Fuels Characteristics

Natural Gas Diesel OilCarbon content [mass %] 73,3 85,9Hydrogen content [mass %] 23,9 14,0Oxygen content [mass %] 0,4 0,05Carbon-to-hydrogen ratio 0 25 - 0 33 0 16Carbon to hydrogen ratio 0,25 0.33 0,16Relative molar mass 17 - 20 ~170Density at 0 oC and 1,013 bar [kg/m3] ~0,83 840B ili t t [°C / 1 b ] 162 f 170 t 380Boiling temperature [°C / 1 bar] -162 from 170 to 380Autoignition temperature [°C] 540 - 560 320 – 330Octane number 120 -130 -Cetane number - 52 - 56Methane number 69 - 99 -

Natural Gas Diesel Oil

• Stoichiometric air/fuel ratio [mass] 17.2 14,5

• Vapour flammability limits [Volume %] 5 - 15 -

• Flammability limits [lambda] 0,7 – 2,1 0,19 - 0,98

• Lower heating/calorific value [MJ/kg] 38 - 50 42,6

• Methane concentration [Volume %] 80 - 99 -

• Ethane concentration [Volume %] 2,7 – 4.6 -

• Nitrogen concentration [Volume %] 0,1 - 15 -

• Carbon dioxide concentration [Volume %] 1 – 5 -

• Sulphur concentration [ppm, mass] < 5 < 50

• Specific CO2 formation [g/MJ] 38 - 50 72

Onboard Storage of Natural Gas Compressed Natural Gas (CNG)

Storage pressure – 250 bar Cylinder Vessel – Steel, Aluminium, Fiber reinforced aluminium

Liquefied Natural Gas (LNG) Cryogenic state (-161ºC, 1t0 60 bar)Maximum volumetric energy density Liquefaction process removes certain impurities like water, dust and

h lihelium It is not explosive Cylinder – Double wall I ll Ni k l t l E t i ll C b t l Inner wall – Nickel steel Exterior wall - Carbon steel Space between two walls filled with a pertile( powder insulating material)

Adsorbent storage (ANG) B d th bilit f th t i l t i il t th Based on the ability of the materials to assimilate methane gas Carbon sorbency – low pressure (12.4 bar) Enhanced capability – By chilling the gas At hi h Si l i l At high pressure – Simple compression vessel

Advantages of Natural Gas Disadvantages

Fairly abundant worldwide

Excellent knock resistance

Low energy density Low engine volumetric efficiency

Its calorific value is identical to diesel

Higher ignition energy requirement Need of large pressurized fuel tank Inconsistent fuel properties

Higher self ignition temperature than diesel

Good charge distribution

Inconsistent fuel properties Refuelling is a slow process

Good charge distribution

Clean burning characteristics

Non – corrosive

Non – toxic

No sulfuric emissions

No cold starting and warmup problems

Operation mode in IC engines SI engine - Sole fuel modeg CI engine - a) Dual fuel mode( 30 to 90% displacement)

- b) Converted to SI to burn only Natural Gas(100% Substitution)(100% Substitution)

CNG COVERSION KIT( Rs 40,000/) CNG cylinder

Tank capacity – 60 litresTank capacity 60 litresFibre composite reinforcement

Pressure regulator – From storage pressure to metering pressure CNG solenoid valve- at the inlet of the regulator CNG solenoid valve- at the inlet of the regulator Gas mixer or Gas injectors Diesel fuel limiter Load regulator( Gas valve linked to accelerator pedal) Load regulator( Gas valve linked to accelerator pedal) Electronic selector switch Cylinder valve – Allow the of CNG during refueling & Outflow to

pressure regulatorpressure regulator

CNG in SI engines Higher compression ratio Higher compression ratio CNG inducted along with air and ignited using spark plug No starting problem Ignition timing has to be advanced(5 to 10º crank angle) High thermal efficiency Low brake power(10%) – Displacement of intake air by the fuel p ( ) p y

vapour Low CO and HC emissions Flexible fuel operation Flexible fuel operation

CNG in CI engines NG – air mixture induction Gas is injected directly into the cylinder Superior starting capability under cold weather conditions

Dual Fuel Engine Performanceg

CATERPILLAR C-10 DFNGENGINE [9]

MATERIAL COMPATIBILITY OF NATURAL GAS

All prices as applicable at Mumbai

Unit Unit -- IVIVAlternative FuelsAlternative Fuels

Introduction l f l f l Depletion of petroleum fuels

Engine Emissions Production and characteristics of alternative fuels Comparison of properties Suitability in existing engines Results and Discussions Results and Discussions Alcohol Hydrogen LPG LPG CNG Biodiesel Biogas

Alcohol

Renewable fuelsh l l h l d h l l h l Methyl alcohol and Ethyl alcohol

Iso-Butanol, n-butanol, pentanol Fermentation of carbohydrates From sugarcane and starchy materials like corn and potatoes Methanol can be produced

Lignite or coal Municipal solid wastes Lignite or coal, Municipal solid wastes

Natural gas

Ethanol can be produced fromp

Feed stock containing carbohydrates such as corn, wheat, sugar-beets and potatoes

Fig. Methanol production from Fig. Methanol production from

coal

Fig. Methanol production from Municipal solid waste

Fig. Ethanol production from grainFig. Ethanol production from grain

Fuel properties

Auto ignition temp(ºC) 300-450 220-300 478 468

Advantages of Alcohol Number of natural resources Number of natural resources

High octane rating – Higher compression ratio

Higher flame speedg p

Less overall emissions

Low sulphur content

Wider flammability limit

High latent heat of vaporization – Cooler intake process

Disadvantages of Alcohol

Low energy content

Combustion of alcohols produce more aldehydes in the exhaust

More corrosive on metals ( Material compatibility)

Poor cold weather starting characteristics

( low vapour pressure and high latent heat of vaporization)

Poor ignition characteristics

Al h l h l t i i ibl fl ( Fl l i it ) Alcohols have almost invisible flames( Flame luminosity)

Human Toxicity

Fire hazard( Storage difficulties) Fire hazard( Storage difficulties)

Requires large fuel tank capacity due to lower calorific Requires large fuel tank capacity due to lower calorific value value

Higher evaporative emission due to higher RVPHigher evaporative emission due to higher RVP

Alcohol in SI enginesMethods

Solution or blend ( Mixture of alcohol and gasoline)

M0 to M85 & E10 to E85

Sole/ neat fuel mode ( 100% methanol or ethanol) Sole/ neat fuel mode ( 100% methanol or ethanol)

Gasohol – 10% ethanol by volume

Feedstock for ethers

Modifications

Increase the size of jets

Retarded ignition timingRetarded ignition timing Retarded ignition timingRetarded ignition timing Dedicated engine- High compression ratio

Development of metal components for antiDevelopment of metal components for anti--corrosion propertiescorrosion propertiesAdvantages

Simplest method

No modifications required No modifications required

Octane number increases

Disadvantages Drop in power output Drop in power output

Vapour lock problem

Phase separation p

Anhydrous alcohol ( 200 proof)

20% Ethanol is most preferable

U f hi h l h l lik B l l h l C l h l T l )Use of higher alcohols like Benzyl alcohol, Cyclohexanol or Toluene)

Cold startability

Increase in aldehyde emissionsy

Corrosion problems on the mechanical components

(Components made of copper, aluminium or brass , Rubber also)

Development of metal components for antiDevelopment of metal components for anti--corrosion corrosion propertiesproperties

Neat Alcohol in SI Engines Same modifications (Jet size, Ignition timing) Same modifications (Jet size, Ignition timing)

Increase in thermal efficiency (10%)

Same power output

Higher fuel consumption(54%)

Low NOx

Low CO and HC

More aldehydes

Low evaporative emissions Low evaporative emissions

Excessive wear (Low viscosity, Lubricity )

Alcohol in CI EnginesTechniques

Alcohol/ diesel solutions – 25% displacement

Alcohol/ diesel emulsions – 25% displacemnet

Alcohol fumigation – 50% Alcohol fumigation 50%

Dual Injection – 85%

Alcohol containing ignition improvers – 100%

Spark ignition of alcohols - 100%

Hot spot Ignition ( Surface Ignition) - 100%

Solution/ Blend

Solution mixture

Water content

T t Temperature

Modifications in Fuel volume delivery, injection timing

Low cetane number

Viscosity decreases

Calorific value reduces

Decrease in thermal efficiency

Low NOx

Power output is less with maximum % of alcohol

No change in CO

High UBHC with increase in ethanol solution %

Smoke and PM emission decrease with increase in ethanol content

Emulsions

25- 30 % displacement of alcohol

Equal amount of Emulsifier and alcoholq

Extent the water tolerance of alcohol / diesel blends

Modification in injection timing and fuel volume delivery

Low calorific value and low cetane number

Reduced power output and thermal efficiency

CO is same CO is same

Viscosity increases( Results in poor mixing)

UBHC increases

NOx increases( Increases in ignition delay)

Cost of emulsifier

Surfactant Sodium lauryl sulphate (0.1%) Ethyl acetate 1 Butanol 1- Butanol Alkali metal soap Sodium Hydroxide ( 2 to 3%) Sodium Hydroxide ( 2 to 3%)

Fumigation 50 80 % Di l t f l h l 50 – 80 % Displacement of alcohol

Alcohol introduced into the engine by carburettor or vapourzer

Use of separate fuel supply system for alcohol and diesel

At low load – Low fuel delivery (Flame quenching)

Increase in power output

More efficiency

CO & UBHC are higher (Flame quenching effect) CO & UBHC are higher (Flame quenching effect)

Low NOx

High latent heat of alcohol cool the intake charge

70% reduction in PM

Flexible to switch over from dual fuel mode to single fuel modemode

Dual Injection 90% displacement 90% displacement Complex and expensive method Alcohol is directly injected into the cylinder and ignited by a pilot

h f di l f lcharge of diesel fuel To initiate the combustion Pilot charge must precede the injection of alcohol More power output(13%) High thermal efficiency Low emissions Low emissions Best suitable in IDI engines Lubrication problem

Spark Ignition 100% displacement Spark ignition must be associated with fuel injection Improved thermal efficiency More power output Low NOx & PM More CO Proper lubrication

Ignition Improvers 10 to 20 % by volume Increase its cetane number Nitrogen based compounds Isoamyl nitrate Tri elthylene glycol dinitrate Kerobrisol Castor oil – Lubricant High NOx Better power output and thermal efficiency

Surface Ignition Glow plugp g 100% displacement To glow continuously throughout the cycle Temperature 900 to 1000ºCp

Alcohol – Feedstock for Ethers Dimethyl ethers ( CH3 O CH3) – Colourless gas Cetane number -55 Sulfur free Diethyl ethers ( CH3-CH2)2O Cetane number – 85-95 High auto ignition temperature g g p Methyl Tertiary Butyl Ether(MTBE) Ethyl Tertiary Butyl Ether(ETBE) Oxygenate Oxygenate 10 – 15% by volume To increase the octane number of gasoline

UnitUnit IVIVUnit Unit -- IVIVH dH dHydrogenHydrogen

INTRODUCTION Possible fuel of future Possible fuel of future Most abundant element in the universe Breakdown hydrocarbons into more simple molecules Electrolysis process (From water) Steam reformation

To split the hydrogen from natural gaso sp e yd oge o a u a gas Gasification of coal Colourless, Odourless and non-toxic Global warming potential of hydrogen is insignificant in Global warming potential of hydrogen is insignificant in

comparison to hydrocarbon based fuels Supply infrastructure cost

F l t d f li f t bil Fuel storage and refueling for automobiles Delivery, dispensing and storage expenses Lack of consumer infrastructure Pipes and fittings can become brittle

Hydrogen Storage Technologies Store hydrogen as a compressed gas y g p g

Least costly method Safety problems (Danger factor) Pressure 200 to 700 bar Pressure 200 to 700 bar

Store the hydrogen as a liquid Cryogenic storage Liquefied hydrogen(-253ºC) Internal pressure(0.6 MPa)

Store as a solid hydrideyMetal hydride (Iron – titanium hydride FeTiH2) Sponge absorbs waterMore hydrogen storage for a given volumeMore hydrogen storage for a given volume High density

Comparable volumetric storage capabilities Both the techniques require 10 times space required by the

5 gallons gasoline tank

Heating energy Heating oil Heating coilWaste exhaust gasWaste radiator coolant heat

By adsorption on activated carbon or carbon nanotubes

Compatibility with IC EngineCompatibility with IC Engine Flash back tendency into the intake manifold Embitterment of the iron components

Hydrogen (Metal Hydride Tank)

Properties H2 HCNG 5 CNG Gasoline

Li it f Fl bilit i i 4 75 5 35 5 15 1 0 7 6Limits of Flammability in air, vol %

4-75 5-35 5-15 1.0 -7.6

Stoichiometric composition inair, vol %

29.53 22.8 9.48 1.76

Mi i f i iti i 0 02 0 21 0 29 0 24Minimum energy for ignition in air, mJ

0.02 0.21 0.29 0.24

Auto ignition Temp, K 858 825 813 501-744

Flame Temperature in air, K 2318 2210 2148 2470

Burning Velocity in NTPa air,cms-1

325 110 45 37-43

Quenching gap in NTP air, cm 0.064 0.152 0.203 0.2

Normalized Flame Emissivity 1.0 1.5 1.7 1.7

Equivalence ratio 0.1-7.1 0.5-5.4 0.7-4 0.7-3.8

Methane Number 0 76 80 -

aNTP denotes normal temperature(293.15K) and pressure(1atm)

Properties of Hydrogen Low density Low density High self ignition temperature Excellent combustion properties Low emissions Wider flammability limits(4- 75%) High flame speed (Fast burning rate) Minimum ignition energy Diffusivity (Easily mixes with air) Diffusivity (Easily mixes with air)

Performance in hydrogen engines

Reduced power in comparison to gasoline engine

High thermal efficiency and low NOx at part load

No CO,HC,SOX and Particulates

NOx is the only pollutant of concern

NOx increases as the fuel ratio increases

Tendency to flashback into the intake manifold

BIODIESEL

Reaction temperatureReaction temperature

The rate of reaction is strongly influenced by the reaction temperature. G ll th ti i d t d l tGenerally, the reaction is conducted close to the boiling point of methanol (60 to 70°C) at atmospheric pressure.atmospheric pressure.

The maximum yield of esters occurs at temperatures ranging from 60 to 80°C at a molar ratio (alcohol to oil) of 6:1.

Further increase in temperature is reported to have a negative effect on the conversionhave a negative effect on the conversion.

Ratio of alcohol to oil:

A molar ratio of 6:1 is normally used in A molar ratio of 6:1 is normally used inindustrial processes to obtain methyl esteryields higher than 98% by weight.

Higher molar ratio of alcohol to vegetable oilinterferes in the separation of glycerol.

l l ti i ti ti lower molar ratios require more reaction time.With higher molar ratios, conversionincreases but recovery decreases due to poorincreases but recovery decreases due to poorseparation of glycerol.

optimum molar ratios depend upon type &p p p ypquality of oil.

Comparative Properties of BiodieselT E S T

L O W S U LF U R C O N T E N TD IE S E L

R A P E S E E DM E T H Y L E S T E R

N E A T R A P E S E E DO IL

R A P E S E E DE T H Y L E S T E R

H Y D R O - G E N A T E DS O Y E T H Y L E S T E R

C E T A N EC E T A N E N U M B E R 4 6 61 .2 42 .6 59 .7 61

F LA S H P O IN T , °C 6 7 180 270 185 144

C LO U D P O IN T °C -1 2 -2 -11 -2 7P O IN T , C

P O U R P O IN T , °C -1 6 -10 N A -20 7

B O IL IN G P O IN T , °C 1 91 347 311 273 142

V IS C O S IT Y , (cs ) @ 40° C

2 .98 5 .6 5 47 .6 6 .1 5 .78

S U LF U R (% ,w t) 0 .036 0 .0 12 0 .02 2 0 .01 2 0 .02 3

N IT R O G E N , p pm 0 6 N A 7 12

H E A T O F C O M B U S T IO N-B T U s/lb . 1 9 ,500

4 6 42017 .500 40 600

17 ,3 70 40 4 00

17 ,5 00 40 5 10

17 ,1 13 39 8 00U s/ b

(g ro ss) -k j/kg (g ross)

4 6 ,420 40 ,600 40 ,4 00 40 ,5 10 39 ,8 00

S P E C IF IC G R A V IT Y 0 .8495 0 .8 802 0 .90 6 0 .87 6 0 .87 2

BIOGAS

INTRODUCTION TO BIOGAS

Biomass is organic matter produced by plants and animals

Bi t pi ll r f r t pr d d b th bi l i l Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen`

Organic waste such as dead plant and animal material, animal feces and kitchen waste can be converted into a animal feces, and kitchen waste can be converted into a gaseous fuel called biogas

Biogas is the product of fermentation of Biomass

i i ll i h l i h CO d Biogas essentially contains methane along with CO2 and traces of water vapour, nitrogen and hydrogen sulfide

Biogas has energy content equivalent to 2/3 of Natural gas

Biogas can be used for cooking, heating or as an automotive fuel

ADVANTAGES OF BIOGAS

Environmentally less polluting

Leak detection is easy Leak detection is easy

Renewable in Nature

Obtained from Diverse Sources

Economically Cheaper

Higher Energy Content

Higher Octane Rating

Promotes rural economy

Wide range of applications

PROPERTIES OF BIOGAS

Calorific value = 35 MJ/m3

O t R ti 130 Octane Rating = 130

Ignition Temperature = 650°C

Air to Fuel ratio (Stoichiometric) = 10:1 Air to Fuel ratio (Stoichiometric) 10:1

Explosive limit = 5 to 15

Contains 50 to 60 % CH4, 30 to 45% CO2, 5-10% H2S, Trace N2 and H2O

BIOGAS : ISSUES

Biogas contains sulfur and water vapourg pimpurities which need to be cleaned

Reduced volumetric efficiency & less partial pressures in the intake manifold causes power pressures in the intake manifold causes power loss

Variable fuel composition affects performance p pand emissions

Inadequate transportation and distribution i f t tinfrastructure

BIOGAS GENERATION REACTIONS

FACTORS AFFECTING BIOGAS GENERATION

pH value of Biomass

Temperature of digestion Temperature of digestion

Solid content of feed

Rate of feed in digesterg

Carbon to Nitrogen ratio in Biomass

Diameter to depth ratio of digester

Retention time for digestion

Stirring of contents of digester

Pressure in the digester

Acid accumulation in digester