1. FUELS
• PETRO CHEMICALS OR HYDRO CARBONS(HC)
• GASOLINE IS A LIQUID OBTAINED FROM CRUDE
OIL/MINERAL OIL/ROCK OIL--ORGANIC COMPOUND
• IT IS A DARK BROWN/ BLACK, FOUL SMELLING LIQUID
• IT UNDERGOES NO OF REFINING PROCESSES IN THE
REFINERY. USUALLY FRACTIONAL DISTILLATION
• HYDROCARBONS WITH MORE CARBON ATOMS HAVE
HIGHER BOILING POINT THAN THE ONE WITH FEWER
CARBON ATOMS.
• HC WITH LOW BOILING POINT ARE COLLECTED AT THE
TOP OF THE TOWER

2. FRACTIONAL DISTILLATION

4. FUELS
FRACTIONS BOILING RANGE NO OF CARBON
ATOMS
USES
PETROLEUM GAS BELOW 40 1-4 FUEL
COOKING/HEATING
PETROL 40-75 5-10 CARS
NAPTHA 75-150 7-14 PLASTICS,
DETERGENT/FEED
STOCK
KEROSENE/PARAFIN 160-250 11-16 AIRCRAFTS,
COOKING
DIESEL OIL 250-300 16-20 CI ENGINES
LUBRICATING OIL 300-350 20-35 WAXES / POLISH
BITUMEN/ASPHALT ABOVE 350 MORE THAN 70 PAVING ROAD

5. PROPERTIES OF FUELS
• BOILING & MELTING POINT INCREASES AS
MOLECULAR SIZE INCREASES
• DENSITY INCREASES AS MOLECULAR SIZE
INCREASES
• VISCOSITY INCREASES WITH MOLECULAR SIZE
• LESS FLAMMABLE WITH INCREASE IN
MOLECULAR SIZE---SO ?
• FUEL WITH LESS CARBON ATOMS IS MORE
VOLATILE & HEATING VALUE INCREASES BY
PROPORTION OF HYDROGEN ATOMS .

6. FUELS
• CRACKING IS PROCESS OF
BREAKING LARGE HC BY
THERMAL & CATALYSTIC
CRAKING
• REFORMATION- WHY? To
improve anti knock
qualities of fuels
• ISOMERISATION- SAME
NO OF MOLECULAR
FORMULA BUT
DIFFERENT CHEMICAL
STRUCTURES

7. FUELS

8. FUELS

9. • N2- 80 % , 02 -20 %
• H2 IN HC FORMS H20 &
O2 FORMS CO2
• BUT INCOMPLETE
COMBUSTION MAY
RESULT IN SOME HC GO
OUT TO FORM CO &
NOX
• VOLATILITY
• RESISTANCE TO SPARK
KNOCK OR
DETONATION
• ANTI RUST
• ANTI ICERS
• DETERGENT-CLEAN
FUEL/CARBURETOR
• DYE FOR COLOUR
AIR/FUEL

10. AIR/ FUEL

11. FUEL PROPERTIES
• VOLATILITY : CRANK CASE
DILUTION, VAPOUR
LOCK,STARTING ISSUES
• GUM DEPOSIT:IMPURITIES
DUE STORAGE, CLOGS
CARBURETOR, CARBON
DEPOSITS
• SULPHUR: CORROSION, LOW
IGNITION TEMP PROMOTING
KNOCKS
• ANTIKNOCK: ABNORMAL
COMBUSTION AFTER SPARK
AT THE PLUG. HOW?
RESULTING IN HIGH PITCH
METALLIC RAPPING NOISE
CALLED PINGING.
• PREIGNITION:HOT SPOTS
BEFORE SPARK PLUG. HOT
EXHAUST VALVE,SPARK PLUG
OR CARBON DEPOSITS
RUMBLE TO MILD
DETONATION/ DULL THUD
SERVICE ISSUES, WRONG
FUELS.DRIVER ISSUE? HOW?

12. COMBUSTION

13. COMBUSTION

14. COMBUSTION

15. COMBUSTION

16. COMBUSTION
• IF T &P OF AF MIXTURE IS
RAISED HIGH ENOUGH,IT
WILL SELF IGNITE
WITHOUT A SPARK
PLUG.IN SI ENGINES
AUTO/PRE IGNITION IS
NOT DESIREABLE .SPARK
PLUG IGNITES AF
MIXTURE AT PROPER
TIME IN
CYCLE.COMPRESSION
RATIO GENERALLY 10:1
TO AVOID PREIGNITION

17. COMBUSTION
• MECHANICAL FACTORS TO
CONTROL COMBUSTION
• QUENCH AREA PREVENTS
LAST PART OF AF MIXTURE
TO DETONATE.IT OCCURS AT
END OF COMPRESSION
STROKE.MIXTURE
SQUEEZED TO PROMOTE
TURBULENCE.
• HEMISPHERE SHAPE HAS A
CENTRAL PLUG.FLAME
TRAVELS A SHORT
DISTANCE. NO END
POCKETS

18. OCTANE NO
• ENGINE DESIGN & COMPRESSION
RATIO DETERMINES THE OCTANE
REQUIREMENT.
• OCTANE MEASURES THE ANTIKNOCK
QUALITY OF FUEL
• HIGHER OCTANE NO,THE MORE
RESISTANT THE GASOLINE IS TO
KNOCK
• 93 IS MORE RESISTANT THAN 89
• GASOLINE THAT DETONATE IS LOW
OCTANE, & THAT RESISTS
DETONATION IS HIGH OCTANE.
• HIGH COMPRESSION RATIO REQUIRES
HIGH OCTANE NO.HIGH
COMPRESSION IS DESIREABLE TO
PRODUCE MORE POWER.BUT?
• VERY HIGH RATIOS MAY DETONATE
.TEL IS NOW OBSOLETE

19. OCTANE NO
• ORGANOMANGANESE &
ALCOHOLS SUBSTITUTES OF
TEL.
• KNOCK OCCURS AT WOT
WHEN ENGINE IS
LOADED/GOING UPHILL
• SOLUTION- HIGH
OCTANE(SLOW BURN)
,IGNITION TIMING
ADVANCE----MEDIUM
OCTANE RETARD IGNITION
OR STARTING COMBUSTION
LATER IN COMPRESSION
STROKE.

20. OCTANE NO

21. DIESEL FUEL
• COMPRESS ONLY AIR ON THE COMPRESSION
STROKE
• HEAT OF COMPRESSION IGNITES FUEL AS IT
SPRAYS INTO THE ENGINE CYCLINDER
• HAS A HIGH COMPRESSION RATIO OF 16:1 TO
22:1
• CONTROLS ENGINE POWER AND SPEED ONLY BY
THE AMOUNT OF FUEL SPRAYED INTO THE
CYCLINDER.MORE FUEL EQUALS MORE POWER

22. DIESEL FUEL
FLASH POINT
• OF A VOLITILE MATERIAL
LOWEST TEMP AT WHICH IT CAN
VAPORIZE TO FORM AN
IGNITABLE MIXTURE IN AIR.
• IT REQUIRES AN IGNITION
SOURCE
• AT FLASH POINT , THE VAPOURS
CEASE TO BURN WHEN SOURCE
OF IGNITION IS REMOVED
• SI ENG, AF MIX IS HEATED ABOVE
ITS FLASH POINT, THEN IGNITED
BY SPARK PLUG.TO AVOID
PREIGNITION, LOW FLASH &
HIGHER AUTO IGNITION.
.IT DOES NOT REQUIRE AN
IGNITION SOURCE
• TEMP AT WHICH VAPOURS
CONTINUE TO BURN AFTER
BEING IGNITED.( SEE NEXT
SLIDES PLEASE)
SELF IGNITION

23. DIESEL FUEL
• VOLATILITY: LESS THAN
PETROL BUT IT ALSO
EMPHASIZES THAT IT HAS
HIGHER HEATING
VALUE.(LONG CHAIN)
• VISCOSITY:LESS OTHERWISE
IT WOULD NOT BREAK INTO
PARTICLES.SMALL
PARTICLES BURN FAST.
• SULPHUR:EXCESSIVE
CYLINDER
WEAR/LUBRICATING OIL
• KNOCK: TIME OF INJECTION
AND ACTUAL BURNING.IF
LAG INCREASES , AMOUNT
OF FUEL ACCUMULATED IS
MORE,ABNORMAL
AMOUNT OF ENERGY IS
RELEASED, EXCESSIVE
PRESSURE RISE AND
AUDIBLE KNOCK.
• A GOOD CI ENGINE HAS
SHORT IGN LAG.
• IGN LAG AFFECT
STARTING,WARM UP, AND
PRODUCES SMOKE

24. DIESEL FUEL
• IMMEDIATELY AFTER INJECTION, THE
FUEL PARTIALLY EVAPORATES WITH A
RESULTING CHILLING OF THE AIR IN
THE IMMEDIATE VACINITY OF EACH
FUEL PARTICLE.HOWEVER, THE
EXTREME HEAT OF COMPRESSION
RAPIDLY HEATS THE FUEL PARTICLES
TO SELF IGNITION POINT AND
COMBUSTION BEGINS.THE FUEL
BURN AS THEY MIX IN THE AIR.THE
SMALLEST PARTICLES BURN RAPIDLY
BUT LARGER TAKES MORE TIME TO
IGNITE BECAUSE HEAT MAY BE
TRANSPORTED INTO THEM TO BRING
THEM TO SELF
IGNITION.COMBUSTION IS SLOWER
AND PRESSURE RISE IS
SMALL(CONSTANT)

25. CETANE NO
• CETANE NO REF TO EASE
WITH WHICH FUEL IGNITES.
• A HIGH CETANE NO IS FAST
BURNING AND IGNITES AT
RELATIVELY LOW TEMP . &
VICE VERSA
• PROCEDURE TO FIND
CETANE IS SIMILAR TO
OCTANE EXCEPT CETANE
100 & ALPHA METHYL
NAPHTHALINE 15 ARE
USED.
• GREATER THE REFINING
DONE ON FUEL, THE LOWER
IS ITS MOLECULAR WEIGHT
,LOWER IS ITS VISCOSITY
,AND GREATER IS ITS COST.
SO CARS USES LIGHT OR
SOME TIMES CALLED NO 2
DIESEL.OTHER TYPE IS USED
IN MASSIVE HEATING
UNITS.
• INVERSE RELATIONSHIP OF
PETROL TO DIESEL

26. NUMERICAL

27. FUEL PROERTIES -TABLE