day_8_alternate fuels and hybrid power train

8/7/2019 Day_8_Alternate Fuels and Hybrid Power Train

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Day 8

• Session Topic– Alternate Fuels– Hybrid Power Train

• Session objectives is to learn about– Various alternate fuels– Configurations of hybrid power train



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Petroleum Fuels

1. Gasoline (North American Term) or Petrol(British term

2. Diesel Fuel

3. Jet Fuel4. Liquefied Petroleum Gas

5. Vapourised Petroleum Gas

6. Compressed Natural Gas



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Distillation of Crude oil and byproducts

C1 to C 4 gasses

LPG

Chemicals

Petrol for vehicles

Jet fuel, paraffin forlighting and heating

Diesel fuels

Lubricating oils, waxes,polishes

Fuels forships,factories andcentralheating

Bitumenfor roadsandroofing

20 0 C

70 0 C

120 0 C

170 0 C

270 0 C

C5 to c9 Naptha

C10 to C16 kerocene

C5 to C10 petrol

C14 to C20 Diesel

C20 to C50lubricating oil

C20 to C70fuel oil

> C70 residue600 0 C

Crude oil

Fractionsincreasing indensity and

boiling point

Fractionatingcolumn

Fractions decreasingin density and boilingpoint



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Substance Density(kg/litre)

Mainconstituents

Boilingtemperature

0C

Ignitiontemperature

0C

Latent heat of vapourisation

kJ/kg

Specific Calorificvalue (MJ/kg)

SI engine fuelRegularPremiumAviation fuel

KeroseneDiesel fuel

0.72-0.7750.72-0.775

0.72

0.77-0.830.82-0.845

86 C, 14 H86 C, 14 H85 C, 18 H

87 C, 13 H86 C, 14 H

25-21025-21040-180

170-260180-360

300400500

250250

380-500------

---250

42.743.543.5

4342.5

Iso-octaneBenzeneToluene

0.690.880.87

84 C, 16 H92 C, 8 H91 C, 9 H

9980

110

410550530

297394364

44.640.240.6

Ethanol

Methanol

0.79

0.79

84 C, 16H,35 O

38 C, 12H,50 O

78

65

420

450

954

1110

26.8

19.7

Fuel Properties

Latent heat and Calorific values on volume basis can be obtained by multiplying per kgvalue with density in kg/litre.



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Substance Air requirement

Theorotical kg/kg

Lower ignition limit(% by volume of gas

in air)

Upper ignitionlimit (% by

volume of gas inair)

SI engine fuel

Regular

PremiumAviation fuel

KeroseneDiesel fuel

14.8

14.7--

14.514.5

0.6

--0.70.60.6

8

--8

7.5

7.5

Iso-octaneBenzeneToluene

15.213.313.4

11.2

1.2

68

7

EthanolMethanol

96.4

3.55.5

1526

Fuel Properties (contd)



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Octane RatingOctane number : It is the percentage by Vol ume of Iso-Octane

present in a mixture of Iso-Octane and Normal heptane.Isooctane has an octane number of 100 (minimal knock) andheptane is 0 (bad knock).

Example: A gasoline with an octane number of 92 has the same

knock as a mixture of 92% isooctane and 8% heptane.The most common type of octane rating worldwide is theResearch Octane Number (RON ). RON is determined byrunning the fuel through a specific test engine with a variable

compression ratio under controlled conditions, and comparingthese results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor OctaneNumber (MON ) or the aviation lean octane rating, which is a

better measure of how the fuel behaves when under load.



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Octane Rating• It is possible for a fuel to have a RON greater than 100, because

isooctane is not the most knock-resistant substance available.Racing fuels, straight ethanol, Avgas and liquified petroleumgas (LPG) typically have octane ratings of 110 or significantlyhigher - ethanol's RON is 129

• A gasoline's octane rating depends on the blend of hydrocarbons in the fuel and other ingredients that are added toit. Tetraethyl lead was long used as an anti-knock additive toimprove gasoline octane. In fact, it was the most effective andleast expensive octane-boosting additive that could be used forthis purpose.



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• But leaded fuel cannot be used in a vehicle with a catalyticconverter because the lead fouls the catalyst. So unleaded fuelmust contain other octane-boosting additives such as MBTE(methyl tertiary butyl ether (MTBE) or alcohol.

• Most unleaded gasoline today is rated at 87 octane, which issufficient for engines with compression ratios of up to about 9to 12. Higher compression engines, engines with turbochargersor superchargers, or ones used frequently for towing should

use a higher grade or premium gasoline.

Octane Rating



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Cetane Rating

• The performance rating of a diesel fuel, corresponding tothe percentage of cetane in a cetane-methylnaphthalenemixture with the same ignition performance.

• Diesel at the pump can be found in two CN ranges: 40-46

for regular diesel, and 45-50 for premium. Premium dieselhas additives to improve CN and lubricity, detergents toclean the fuel injectors and minimize carbon deposits,water dispersants, and other additives depending ongeographical and seasonal needs.

• Some fuel additives used to raise the cetane number areeg. alkyl nitrates and di-tert-butyl peroxide .



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Compressed Natural Gas

•Compressed Natural Gas

(CNG) is a substitute forgasoline (petrol) or diesel fuel. It is considered to be anenvironmentally "clean" alternative to those fuels. It ismade by compressing purified natural gas, and is typicallystored and distributed in hard containers.

• In response to high fuel prices and environmental concerns,compressed natural gas is starting to be used in light-dutypassenger vehicles and pickup trucks, medium-dutydelivery trucks, and in transit and school buses.

• Compressed natural gas (CNG) is natural gas pressurizedand stored in welding bottle-like tanks at pressures up to3,600 psig. Typically, it is same composition of the local"pipeline" gas, with some of the water removed.



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Other Fuels for Engines

1. Hydrogen

2. Biodiesel/Biofuels

1. Biobutanol,

2. Peanut oil3. Vegoils,

4. Bioethanol,

5. Biomethanol6. Wood alcohol

7. Other biofuels



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Biodiesel

• Biodiesel (mono alkyl esters) is a cleaner-burning diesel fuelmade from natural, renewable sources such as vegetable oils.

• Biodiesel operates in compression ignition engines likepetroleum diesel thereby requiring no essential enginemodifications.

• Moreover it can maintain the payload capacity and range of conventional diesel. Biodiesel fuel can be made from new orused vegetable oils and animal fats.

Advantages of biodiesel- The lifecycle production and use of biodiesel produces

approximately 80% less carbon dioxide emissions, and almost100% less sulphur dioxide.



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- Combustion of biodiesel alone produces over a 90% reductionin total unburned hydrocarbons, and a 75-90% reduction inaromatic hydrocarbons. Biodiesel further provides significantreductions in particulates and carbon monoxide than

conventional diesel fuel.- Biodiesel is the only alternative fuel that runs in any

conventional, unmodified diesel engine.- Needs no change in refueling infrastructures and spare part

inventories.- Maintains the payload capacity and range of conventionaldiesel engines.

Biodiesel



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Advantages of biodiesel

- Diesel skilled mechanics can easily attend to biodiesel

engines.- 100% domestic fuel.- Neat biodiesel fuel is non-toxic and biodegradable. Based onAmes Mutagenicity tests, biodiesel provides a 90% reductionin cancer risks.- Cetane number is significantly higher than that of conventional diesel fuel (CN: 55-70)- Lubricity is improved over that of conventional diesel fuel.- Has a high flash point of about 300 F compared to that of conventional diesel, which has a flash point of 125 F.



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Disadvantages of biodiesel

Some of the disadvantages of biodiesel are:

-Quality of biodiesel depends on the blend thus quality can betampered.

-Biodiesel has excellent solvent properties. Any deposits in the filtersand in the delivery systems may be dissolved by biodiesel and resultin need for replacement of the filters.

- There may be problems of winter operatibility.

- Spills of biodiesel can decolorize any painted surface if left for long.

- Neat biodiesel demands compatible elastomers (hoses, gaskets, etc.).



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Emissions B100 B20

Regulated Emissions

Total Unburned Hydrocarbons -93% -30%

Carbon Monoxide -50% -20%

Particulate Matter -30% -22%

NOx +13% +2%

Non-Regulated EmissionsSulphates -100% -20%*

Polyciclic Aromatic Hydrocarbons (PAH)** -80% -13%

NPAH (Nitrated PAHs)** -90% -50%***

Ozone Potential of Speciated HC -50% -10%

Life-Cycle Emissions

Carbon Dioxide (LCA) -80%

Sulphur Dioxide (LCA) -100%

*Estimated from B100 results. **Average reduction across all compounds measured.

***2-nitroflourine results were within test method variability.

Reduction of emission from biodiesel compared to petroleum diesel

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Hydrogen Vehicle

• Hydrogen Vehicles use hydrogen as primary source of power forlocomotion

•Hydrogen is used in two ways for generating power (i) by directlycombusting in the IC engine and (ii) by way of electrochemical

conversion in a fuel cell.•In combustion method, the hydrogen is burned in engines infundamentally the same method as traditional gasoline cars.

•In fuel-cell conversion method, the hydrogen is reacted withoxygen to produce water and electricity , the produced electricalpower is used to power electric motors.

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Hydrogen Vehicle

Hydrogen-Powered 1965 Cobra Replica

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Sources of Hydrogen

The required hydrogen for automotives can be obtained throughvarious thermochemical processes such as

•Coal gasification, as well as from natural gas,

•By thermolysis from LPG and biomass through biomassgasification

•Through microbiological process to produce biohydrogen

•From water using electrolysis

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The hydrogen option: diverse feedstocks

Crude Oil

Coal

Natural Gas

Nuclear

NuclearSolar

Hydro

Wind

Wave

Geothermal

Wood

Organic Waste

Biomass

Gasifier

Gasifier

Reformer

Gasifier

Gasifier

Gasifier

Electric Power PlantPhoto-voltaic

Generator

Generator

Generator

Electric Power Plant

Electrolyzer

Hydrogen

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Hydrogen Fueling Station Components

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Hydrogen-Status in IndiaMetal Hydride StorageDeveloped by Banaras Hindu University (BHU)

Use of hydrogen in IC enginesIIT, Delhi developed hydrogen gas induction system for IC

engines - Small gensets to large capacity S. I. engines.

Development of Fuel CellsBHEL R&D, Hyderabad,

SPIC Science Foundation-Chennai,Glass & Ceramic Research Institute – Kolkata

IICT – Hyderabad,

DRDO – Naval Material Research Lab.,

TERI – Delhi

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• The advantage of hydrogen is that it can be directly producedonboard and consumed.

• However, the car running on hydrogen produced usinghydrocarbon results in more pollution than a car running ongasoline or diesel.

• This is because, although the hydrogen fuel cells produce lessCO 2, the production of hydrogen results in higher emission.

• Hence the production of hydrogen using fossil fuels is notadvisable and other methods of production are welcome.

• At present production of hydrogen from other sources are noteconomically viable .

Hydrogen for Automotives

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Hydrogen’s potential: light-vehicle CO 2emissions

Lb CO 2 / 100 Miles

0

20

40

60

80

100

120

Gasoline Diesel CNG Gasoline Diesel NGreforming

Gridelectrolysis

From processes to produce fuelFrom combustion of fuel

Renewableelectrolysis

H2 H2

Conventional ICEs

Hybrid ICEs

Hybrid H2 FCVs

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As a 2007 article in Technology Review argued,

In the context of the overall energy economy, a car like the BMW Hydrogen 7 would probably produce far more carbon dioxideemissions than gasoline-powered cars available today.

And changing this calculation would take multiple breakthroughs--which study after study has predicted will take decades, if theyarrive at all.

In fact, the Hydrogen 7 and its hydrogen-fuel-cell cousins are, inmany ways, simply flashy distractions produced by automakers whoshould be taking stronger immediate action to reduce thegreenhouse-gas emissions of their cars.

Source: wikipedia

Hydrogen for Automotives

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Limitations of Hydrogen Use in AutomobilesAt present the use of hydrogen for power plant in the automobile hasfollowing serious limitations, be it direct combustion in the engine orthrough fuel cell.

• Hydrogen has the lowest volumetric energy density at ambientconditions, one third of methane. This necessitates compression of hydrogen to high pressure levels and/or cryogenic storage leading tovery high costs.

Even when the fuel is stored as a liquid in a cryogenic tank or in apressurised tank , the volumetric energy density (megajoules per m 3)is small relative to that of gasoline.

Because of the energy required to compress or liquefy the hydrogengas, the supply chain for hydrogen has lower well-to-tank efficiencycompared to gasoline.

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Limitations of Hydrogen Use in Automobiles

• Some research has been done into using special crystallinematerials to store hydrogen at greater densities and at lowerpressures, however with additional cost.

•Currently the use of hydrogen in fuel cells for power plant in theautomobiles is very expensive , and lead to a fragile power plantwhich may not survive the bumps that an automobile experience.

•Current technologies utilize between 25 to 50 percent of the higherheating value to produce hydrogen and deliver it to the vehicletank. Electrolysis, currently the most inefficient method of producing hydrogen, uses 65 percent to 112 percent of the higherheating value on a well-to-tank basis, owing to the comparativelyinefficient conversion of fuels to electric power

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Fuel Cost Comparison for H2 & Its Competitors

*Assumes: 1) FCV’s have 50% and H2ICE’s 10-20% better fuel economy thanadvanced gasoline or hybrid vehicles,and 2) all fuels (gasoline or H2) are taxedon an equivalent BTU/mile basis.

Projected CA Elec. Prices

Key Issues:• Dispensed hydrogen more costly per mile than gasoline• Electrolysis more expensive than NG reforming, due

largely to electricity costs

Hydrogen Production Cost for Vehicle Fueling at 5000 psi*

H y d r o g e n

R e l a t i v e

F u e l C o s t / M

i l e

Electricity Cost, Cents/kWh

FossilNuclear

WindBiomass

(Future) Solar Photovoltaic

0

2

4

6

8

10

12

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Proj ected CA Elec. Prices

Gasoline

H2 from electrolysis

H2 from natural gas

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Limitations of Hydrogen Use in Automobiles

• As stated earlier, the use of hydrogen produced from fossil fuels in

automobile to power the vehicle would result in more pollution thanan automobile which is running on the fossil fuel itself.

This is because the production of hydrogen from fossil fuels lead tomore production of green-house effect gasses.

With all these discouraging facts on the use of hydrogen onboard anautomobile, efforts are on to invent new technologies which would

lead to the production of hydrogen at lesser cost and pollution andease of storing.

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Automobiles using hydrogen for power plant

• In 1807, François Isaac de Rivaz built the first hydrogen-fueled

internal combustion vehicle. However, the design was veryunsuccessful.

• A BMW hydrogen car (BMW H2R) broke the speed record forhydrogen cars at 186 mi/h (300 km/h), and BMW has an even newerHydrogen 7 model.

• BMW — The BMW Hydrogen 7 is powered by a dual-fuel InternalCombustion Engine and with an Auxiliary power based on UTCPower fuel cell technology.

• Mazda has developed Wankel engines to burn hydrogen.

• DaimlerChrysler — F-Cell , a hydrogen fuel cell vehicle based onthe Mercedes-Benz A-Class.

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The BMW Hydrogen 7 car

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• Ford Motor – Focus FCV , a hydrogen fuel cell modification of

the Ford Focus, and E-350 buses, which began being leased in late2006.• General Motors — multiple models of fuel cell vehicles includingthe Hy-wire and the HydroGen3

• Honda – currently experimenting with a variety of alternativefuels and fuel cells with experimental vehicles based on the HondaEV Plus, most notable the Honda FCX , powered by a front-mounted 80 kW AC electric motor, with 20 kW pancake motors• Hyundai — Tucson FCEV , based on UTC Power fuel celltechnology• Mazda - RX-8 , with a dual-fuel (hydrogen or gasoline) rotary-engine

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• Nissan — X-TRAIL FCV, based on UTC Power fuel celltechnology

• Morgan Motor Company – LIFEcar , a performance-orientedhydrogen fuel cell vehicle with the aid of several other Britishcompanies

• Toyota – The Toyota Highlander FCHV and FCHV-BUS arecurrently under development and in active testing.


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Combustive properties of Hydrogen:

• wide range of flammability

• low ignition energy

• small quenching distance

• high autoignition temperature

• high flame speed at stoichiometric ratios

• high diffusivity

• very low density

Hydrogen Fuelled IC engines

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• Stoichiometric ratio of A:F for hydrogen is 34:1 by mass (forgasoline it is 14.7:1 )

•This means hydrogen engine require larger amount of air forcomplete combustion.

• Depending the method used to meter the hydrogen to the engine,the power output compared to a gasoline engine can be anywherefrom 85% (intake manifold injection) to 120% (high pressureinjection).

• Because of hydrogen’s wide range of flammability, hydrogenengines can run on A/F ratios of anywhere from34:1 (stoichiometric) to 180:1.


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Combustion Chamber Volumetric and Energy Comparison for Gasoline andHydrogen Fueled Engines


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• Premature ignition is a much greater problem in hydrogen fueled

engines than in other IC engines, because of hydrogen’s lowerignition energy, wider flammability range and shorter quenchingdistance.

•Hydrogen fuel delivery system can be

(i) central injection (or “carbureted”),(ii) port injection and

(iii) direct injection.

•The power output of a direct injected hydrogen engine is 20% morethan for a gasoline engine and 42% more than a hydrogen engineusing a carburetor.


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Engine Design:

•The most effective means of controlling pre-ignition and knock is tore-design the engine for hydrogen use, specifically the combustionchamber and the cooling system.

•A disk-shaped combustion chamber (with a flat piston and chamber

ceiling) can be used to reduce turbulence within the chamber. Thedisk shape helps produce low radial and tangential velocitycomponents and does not amplify inlet swirl during compression.

•Since unburned hydrocarbons are not a concern in hydrogen

engines, a large bore-to-stroke ratio can be used with this engine.•To accommodate the wider range of flame speeds that occur over agreater range of equivalence ratios, two spark plugs are needed. Thecooling system must be de-signed to provide uniform flow to all

locations that need cooling.


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Hydrogen Fuelled IC engines• Additional measures to decrease the probability of pre-ignition arethe use of two small exhaust valves as opposed to a single large one,

and the development of an effective scavenging system , that is, ameans of displacing exhaust gas from the combustion chamber withfresh air.

•Due to hydrogen’s low ignition energy limit, igniting hydrogen is

easy and gasoline ignition systems can be used.•At very lean air/fuel ratios (130:1 to 180:1) the flame velocity isreduced considerably and the use of a dual spark plug system ispreferred.

•Spark plugs for a hydrogen engine should have a cold rating andhave non-platinum tips . A cold-rated plug is one that transfers heatfrom the plug tip to the cylinder head quicker than a hot-rated spark plug. Platinum-tip spark plugs should also be avoided since platinumis a catalyst, causing hydrogen to oxidize with air.

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Hydrogen Internal Combustion Engine


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Crankcase ventilation is even more important for hydrogen enginesthan for gasoline engines.

Crankcase Ventilation





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• As with gasoline engines, unburnt fuel can seep by the pistonrings and enter the crankcase .

•Since hydrogen has a lower energy ignition limit than gasoline,any unburnt hydrogen entering the crankcase has a greaterchance of igniting . Hydrogen should be prevented fromaccumulating through ventilation.

•Ignition within the crankcase can be just a startling noise orresult in engine fire . When hydrogen ignites within thecrankcase, a sudden pressure rise occurs. To relieve this pressure,a pressure relief valve must be installed on the valve cover.•Since hydrogen exhaust is water vapor , water can condense inthe crankcase when proper ventilation is not provided. This mayresult in poor lubrication and result in high engine wear .

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• Hydrogen engines have high thermal efficiency compared gasoline

engines due to the high ratio of specific heats of hydrogen (1.4)when compared to that of gasoline vapour (1.1)

•Emission:The combustion of hydrogen with oxygen produces water as its only

product: 2H 2 + O 2 = 2H 2O

The combustion of hydrogen with air however can also pro-duceoxides of nitrogen (NO x): H 2 + O 2 + N 2 = H 2O + N 2 + NO x

The oxides of nitrogen are created due to the high temperaturesgenerated within the combustion chamber during combustion.




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Hydrogen Fuelled IC enginesEmission:

Emissions for a Hydrogen Engine

The emission of NO x is of the same order as that of gasolineengine, however the absence of emission of CO and CO 2 notable.




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Power

• Hydrogen burning in engine results in high gas temperatuers dueto high flame temperature resulting in high production of NO x.

•Therefore, usually hydrogen is burned with very lean mixtures

(more of air than stoichiometric ratio) to keep the temperatures atlow values. This leads to a larger volume of cylinder .

•Hence hydrogen engines invariably use superchargers andturbochargers to keep up with the power to size ratio.

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COMPOSITION

• Major components of Natural gas are Methane, Ethaneand Propane.

•The proportions of these gases vary according to theregion where the gas was recovered.

•Other Components are Carbon Di Oxide, Nitrogen andSulphur, which may occur in Trace Amounts.

Compressed Natural Gas (CNG) for Vehicles

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CNG AS A FUEL1. Natural gas is a safe Fuel.2. It has a Vapour Density nearly three times lighter than Air,

hence it rises and dissipates quickly when released.3. It has excellent Anti-Knock qualities which allows use of

Higher Compression Ratios for improved Power and Better fuel

Efficiency.4. Combustion with Natural Gas is complete and homogeneous.

• This reduces the levels of unburnt Hydrocarbons, CarbonMonoxide and Hydrocarbons.

5. It exhibits very low particulate emissions.

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CNG Composition

Methane 85-90%

Ethane 4-5%

Propane 1.7-2%

C4 & Higher 0.7-0.8%C6 & Higher 0.2-0.3%

CO2+N2. 3-9%

Hydrocarbon 0.1-0.2%

Oxygen 0.5-0.6%

Oxygen 0.5-0.6%

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Natural Gas Composition

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Properties Gasoline CNG

Motor octane number 80–90 120

Molar mass (kg/mol) 110 16.04

Carbon weight fraction (mass%) 87 75

(A/F)s

14.6 16.79

Stoichiometric mixture density (kg/m 3) 1.38 1.24

Lower heating value (MJ/kg) 43.6 47.377

Flammability limits (vol% in air) 1.3–7.1 5–15

Spontaneous ignition temperature ( C) 480–550 645

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• The ignition and burning characteristics of CNG are considerablydifferent from that of gasoline.

• CNG has a longer ignition delay time than most hydrocarbons, andhas higher minimum ignition energy than gasoline.

• Thus when CNG is used in a gasoline fuelled engine, thecombustion duration becomes relatively long and more advancespark timing is required.

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Case study on CNG Engine

• In a case study on retrofitted CNG fuelled engines showed thepotential for higher FCE (Fuel Conversion Efficiency) andsignificant reduction of emissions. The following concluding

remarks were drawn from the study• Retrofitted CNG engine produces around 16% less BMEP andconsumes 17–18% less BSFC, or consumes an average of 1.65 MJ less energy per kWh at WOT condition with CNGcompared to gasoline.

• The engine shows an average of 2.90% higher FCE nearly atstoichiometric air–fuel ratio ( λ=1) with CNG at WOTcondition and this higher value decreases with the decrease of λ value.

M.U. Aslam et al., An experimental investigation of CNG as an alternative fuel for aretrofitted gasoline vehicle, Fuel, Volume 85, Issues 5-6, March-April 2006, Pages 717-724

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• On average retrofitted engine reduced CO by around 80%,CO2 by 20% and HC by 50% and increases NO x emissions byaround 33% with CNG compared to gasoline.

• For reducing CNG vehicles efficiency penalty due to heavier

CNG storage tank and for providing easy refueling it isrequired to develop lighter CNG storage tank (400+ km) andextensive networks of CNG supply stations at convenientlocations through out the country.

• Retrofitted CNG fuelled engines can be used for the momentfor economic, environment and energy security reasons.

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NO x and HC concentration vs. engine speed at WOT.

Filled rhombus: NO x concentration with gasoline;

Open rhombus: NO x concentration with CNG;

Filled triangle: HC concentration with gasoline;

Open triangle: HC concentration with CNG.

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LPG f A t ti



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LPG for Automotive power

• LPG is a by-product of natural gas processing or a product that

comes from crude oil refining and is composed primarily of propane and butane with smaller amounts of propylene andbutylenes.

• Since LPG is largely propane, the characteristics of propane

sometimes are taken as a close approximation to those of LPG.Composition of LPG and CNG is given in the following table.

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Some of the components of LPG



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Component Chemical Formula Boiling Point C(@ atm. pr)

Propane & derivatives C3H8 -42.1

Butane &derivatives C4H10 -0.5 to -11.7

Propylene C3H6 -47.7

Butene (s) C4H8 +3.7 to -6.47Ethane C2H6 -88.6

Ethylene C2H4 -103.7

Pentane(s) C5H12 -27.9 to 36.1

Hexane (s) C6H14 60.2 to 69.0

Methyl Mercaptan CH3SH 5.8

Ethyl Mercaptan C2H5SH 36.7

Sulphides - -60.7 to 37.3

Some of the components of LPG

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Physical Properties of LPG:

• Boiling Point: The boiling point of LPG presentlymarketed ranges from -42 C to -5 C.• Density/Specific Gravity: LPG in gaseous state is nearly

twice as heavy as air. Any leakage of LPG. therefore, tends tosettle down at floor level, particularly in depressions, pits,drains etc.

• Ground level ventilation to disperse leaking gas and preventaccumulation is therefore most important. However, liquidLPG is almost half as heavy as water.

• Liquid LPG expands to 246 volumes of gaseous LPG. Theleakage of liquid LPG is therefore very dangerous.

• Its flammability limits (2.1-9.5 vol.%) and auto ignitiontemperature (450 degrees C) are also lower than natural gas

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Calorific value of LPG: 94 MJ/m 3 or 26.1 kWh

Calorific Value of NG: 38 MJ/m 3 or 10.6 kWh

• Although LPG has a relatively high energy content per unit mass,its energy content per unit volume is low.

• Thus LPG tanks take more space and weigh more than petrol ordiesel fuel tanks.

• The range of LPG vehicles is equivalent to that of petrol or dieselvehicles.

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• The main constituent of LPG is propane. Lower carbon-to-hydrogen ratio, higher octane rating and its ability to form ahomogeneous mixture inside the combustion chamber enable it toproduce lesser emissions compared to conventional fuels.

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Advantages of LPG as fuel for automotive engines

• It has low cold-start emissions due to its gaseous state.

• It has lower peak pressure during combustion, which generallyreduces noise and improves durability; noise levels can be lessthan 50% of equivalent diesel engines.

• LPG fuel systems are sealed and evaporative losses arenegligible.

• It is easily transportable and offers ‘stand-alone’ storagecapability with simple and selfcontained LPG dispensingfacilities, with minimum support infrastructure.

• LPG vehicles do not require special catalysts.

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• It contains negligible toxic components.

• LPG has lower particle emissions and lower noise levels relativeto diesel, making it more attractive for urban areas.

• Its low emissions have low greenhouse gas effects and low NOxprecursors.

• Relative to other fuels, any increases in future demand for LPGcan be easily satisfied from both natural gas fields and oil refinerysources.

• Emissions of PAH and aldehydes are much lower than those of diesel-fuelled vehicles.

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Disadvantages of LPG as fuel for automotive engines• Although LPG has a relatively high energy content per unit

mass, its energy content per unit volume is lower than diesel,which explains why LPG tanks take more space than diesel fueltanks. They are pressure vessels so that they also weigh more thandiesel tanks.• It is heavier than air, which requires appropriate handling.• Though the lower flammability limit for LPG is actually higherthan the lower flammability limit for petrol, the vapourflammability limits in air are wider than those of petrol, whichmakes LPG ignite more easily,

• It has a high expansion coefficient so that tanks can only befilled to 80% of capacity.• LPG in liquid form can cause cold burns to the skin in case of inappropriate use.

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Fuel Properties Table 1

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Fuel Properties Table 1 (..contd)

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Notes:

(1) Octane values are for pure components. Laboratory engineResearch and Motor octane rating procedures are not suitablefor use with neat oxygenates. Octane valuesobtained by these methods are not useful in determining knock-limited compression ratios for vehicles operating on neatoxygenates and do not represent octane performance of oxygenates when blended with hydrocarbons. Similar problemsexist for cetane rating procedures.(2) The higher heating value is cited for completeness only.

Since no vehicles in use, or currently being developed forfuture use, have powerplants capable of condensing themoisture of combustion, the lower heating value should be usedfor practical comparisons between fuels.

Note for table-1 Fuel Properties

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(3) Calculated.(4) Pour Point, ASTM D 97 from Reference ( c ).

(5) Based on cetane.(6) For compressed gas at 2,400 psi.Sources:(a) The basis of this table and associated references was taken from: AmericanPetroleum Institute (API), Alcohols and Ethers, Publication No. 4261, 2nd ed.(Washington, DC,

July 1988), Table B-1.(b) “Alcohols: A Technical Assessment of Their Application as Motor Fuels,” APIPublication No. 4261, July 1976.(c) Handbook of Chemistry and Physics, 62nd Edition, 1981, The Chemical RubberCompany Press, Inc.(d) “Diesel Fuel Oils, 1987,” Petroleum Product Surveys, National Institute for

Petroleum and Energy Research, October 1987.(e) ARCO Chemical Company, 1987.(f) “MTBE, Evaluation as a High Octane Blending Component for UnleadedGasoline," Johnson, R.T., Taniguchi, B.Y., Symposium on Octane in the 1980’s,American Chemical Society,Miami Beach Meeting, September 10-15, 1979.

Note for table-1 Fuel Properties

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FUTURE VEHICLES

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Summary



Summary

In this session the following topics were discussed– Alternate Fuels for automotive engines– Hybrid power train

day_8_alternate fuels and hybrid power train

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