INTERNAL COMBUSTION ENGINES ME 410 EXPERIMENT 4 By Dr. Ahmet - - PowerPoint PPT Presentation

INTERNAL COMBUSTION ENGINES ME 410 EXPERIMENT 4

By

• Dr. Ahmet YOZGATLIGİL

THE INTERNAL COMBUSTION ENGINE PURPOSE

THE PRODUCTION OF MECHANICAL POWER FROM THE CHEMICAL ENERGY CONTAINED IN THE FUEL

INTERNAL versus EXTERNAL COMBUSTION ENGINES

n CHEMICAL ENERGY IS CONVERTED INTO

THERMAL ENERGY BY COMBUSTION

n THERMAL ENERGY IS CONVERTED INTO

MECHANICAL ENERGY INTERNAL COMBUSTION ENGINES BOTH PROCESSES ARE IN THE SAME CHAMBER EXTERNAL COMBUSTION ENGINES THE PROCESSES ARE IN DIFFERENT CHAMBERS

EXTERNAL COMBUSTION ENGINE

STEAM LOCOMOTIVE

COMBUSTION BOILING WATER STEAM PISTON

INTERNAL COMBUSTION ENGINE

HISTORY

J.J.E. LENOIR (1822 - 1900) DEVELOPED THE FIRST MARKETABLE ENGINE (1860) 5000 ENGINES WERE SOLD DURING 1860-1865 FUEL : COAL-GAS / AIR MIXTURE DURING THE FIRST HALF OF INDUCTION : GAS AND AIR ARE DRAWN INTO THE CYLINDER DURING THE SECOND HALF OF INDUCTION : MIXTURE IS IGNITED BY A SPARK AND THE GAS BURNS AND THE PRESSURE RISES AND THE GAS EXPANDS AND DELIVERS POWER TO THE PISTON

LENOIR’S COMBUSTION ENGINE

n

DOWN STROKE

n INDUCTION n COMBUSTION n EXPANSION

n

UP STROKE

n EXHAUST

HISTORY

NICOLAUS A. OTTO (1832-1891) EUGEN LANGEN (1833-1895) IN 1867 THEY DEVELOPED THE LENOIR ENGINE THE THERMAL EFFICIENCY OF THE ENGINE INCREASED FROM 5 % TO 11 % AGAIN 5000 ENGINES WERE BUILT AND SOLD IGNITION WAS BY A GAS FLAME

HISTORY

IN 1876 OTTO PROPOSED A CYCLE WITH 4 PISTON STROKES FIRST STROKE : INDUCTION SECOND STROKE : COMPRESSION THIRD STROKE : EXPANSION FORTH STROKE : EXHAUST BY 1890 NEARLY 50 000 ENGINES HAD BEEN SOLD

COMPARISON OF LENOIR AND OTTO CYCLES

OTTO & LANGEN OTTO 4 STROKE HORSEPOWER 2 2 WEIGHT KG (approx.) 1800 570 DISPLACEMENT (liters) 80 5 POWER STROKES/min 28 80 SHAFT SPEED (rpm) 90 160 MECH.EFFICIENCY % 68 84 OVERALL EFF. % 11 14 THERE WAS AN ENOURMOUS REDUCTION IN THE ;

n ENGINE WEIGHT n ENGINE VOLUME (DISPLACE VOLUME)

VALVE MECHANISM

MULTIPLE CYLINDER ENGINES

RECIPROCATING ENGINES WANKEL ENGINE ROTARY ENGINES TYPES OF INTERNAL COMBUSTION ENGINES

SPARK IGNITION ENGINES COMPRESSION IGNITION ENGINES (Diesel) RECIPROCATING ENGINES

DIESEL ENGINE

IN SEARCH OF AN ALTERNATIVE FUEL ENGINE (COAL) ALFRED DIESEL INVENTED THE COMPRESSION IGNITION ENGINE (1892). THE ENGINE USED THE SAME THERMODYNAMIC CYCLE AS THE OTTO ENGINE. HOWEVER, COMBUSTION WAS INITIATED BY SELF IGNITION OF THE FUEL INSTEAD OF AN ELECTRIC SPARK.

DURING INDUCTION ONLY AIR WAS INDUCED. THIS MEANT THAT THE THROTTLE VALVE THAT WAS USED IN THE OTTO ENGINE WAS NOT NEEDED. THE ENGINE COULD TAKE IN AS MUCH AIR AS POSSIBLE TODAY EXCEPT FOR THE CHEAP SMALL ONES, ALMOST ALL DIESEL ENGINES ARE SUPERCHARGED. AS THE ENGINE IS PUMPED WITH MORE AIR ITS EFFIECIENCY AND POWER INCREASES. THE LIMITS ARE SET BY THERMODYNAMICS AND MATERIAL PROPERTIES.

AIR IS COMPRESSED TO HIGHER TEMPERATURES AND PRESSURES THAN THE OTTO CYCLE. FOR NATURALLY ASPIRATED DIESEL ENGINES THE TEMPERATURE AND PRESSURE OF THE AIR INCREASES TO 900 K AND 40 ATM, RESPECTİVELLY. FOR SUPERCHARGED DIESEL ENGINES THE TEMPERATURE AND PRESSURE OF THE AIR MAY INCREASE TO1000 K AND 70 ATM, RESPECTİVELY.

TOWARDS THE END OF THE COMPRESSION STROKE THE FUEL IS INJECTED AS FINE ATOMIZED SPRAY. SOME OF THE VAPORIZING DROPLETS FORM COMBUSTIBLE MIXTURES AND AUTOIGNITE. SELF IGNITION OF THE FUEL MAY OCCUR IN SEVERAL POCKETS OF COMBUSTIBLE MIXTURE AT THE SAME TIME. THE REST OF THE EVAPORATING DROPLETS RAPIDLY EVAPORATE AND ENTER THE COMBUSTION REACTION WHILE THE REST OF THE FUEL (80 % OR MORE) IS BEING INJECTED INTO THE REACTION ZONE.

ALTHOUGH THE COMBUSTION BEGINS BY SELF IGNITION OF SOME OF THE FUEL IT CONTINUES BY THE DIFFUSIVE COMBUSTION OF THE REST OF THE FUEL. THERE ARE TWO IMPORTANT RESULTS :

• 1. WHEN COMBUSTION

BEGINS BY SELF IGNITION IT DOESN’T MATTER HOW MUCH AIR THERE IS OR HOW BIG THE COMBUSTION CHAMBER IS. AUTOIGNITION OCCURS IN LOCAL POCKETS.

• 2. THE RATE OF THE DIFFUSIVE COMBUSTION IS

CONTROLLED BY THE RATE OF THE INJECTION.

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TURBOCHARGED 4 STROKE ENGINE

4 STROKE CYCLE ENGINE 2 STROKE CYCLE ENGINE

GASOLINE

COLLECTION OF HYDROCARBON COMPOUNDS WITH SIMILAR DENSITIES

EXAMPLE

L M N

O H C

18 8H

C (octane) (mixture)

EXHAUST EMISSIONS

CARBON DIOXIDE CO2 CARBON MONOXIDE CO NITRIC OXIDES NOX HYDROCARBONS HC

CI ENGINES :SOOT PARTICLES

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ENVIRONMENTAL AND HEALTH IMPACTS

"Soot -- or black carbon -- may be responsible for 15 to 30 percent of global warming, yet it's not even considered in any of the discussions"

Professor Mark Z. Jacobson,

Stanford University

MODERN DESIGN

ELECTRONIC CONTROL IGNITION SYSTEMS

INJECTION SYSTEMS INDUCTION SYSTEMS

MICROPROCESSOR CONTROL OXYGEN SENSORS

SPEED SENSORS TEMPERATURE SENSORS PRESSURE SENSORS…….ETC

MODERN DESIGN

COMPUTER AIDED DESIGN THERMODYNAMIC CYCLE SIMULATION

GAS FLOW SIMULATION COMBUSTION MODELLING

FINITE ELEMENT ANALYSIS COMPUTER AIDED MANUFACTURING