Podcast
Questions and Answers
What is the indicated horsepower (I.P) calculated in kilowatts?
What is the indicated horsepower (I.P) calculated in kilowatts?
What is the formula used to calculate brake power (B.P)?
What is the formula used to calculate brake power (B.P)?
How much heat is lost to the cooling water (Q.w) in kilowatts?
How much heat is lost to the cooling water (Q.w) in kilowatts?
What is the total mass of dry exhaust gases (in kg/sec)?
What is the total mass of dry exhaust gases (in kg/sec)?
Signup and view all the answers
What is the heat lost to radiation in kilowatts?
What is the heat lost to radiation in kilowatts?
Signup and view all the answers
What is the purpose of the intake stroke in a four-stroke Otto cycle engine?
What is the purpose of the intake stroke in a four-stroke Otto cycle engine?
Signup and view all the answers
Who is considered the inventor of the modern internal combustion engine?
Who is considered the inventor of the modern internal combustion engine?
Signup and view all the answers
In the Otto cycle, what initiates combustion in the cylinder?
In the Otto cycle, what initiates combustion in the cylinder?
Signup and view all the answers
During which stroke of the Diesel cycle is the fuel injected into the cylinder?
During which stroke of the Diesel cycle is the fuel injected into the cylinder?
Signup and view all the answers
What is a potential problem that can occur if the initial pressure in an Otto cycle engine is too high?
What is a potential problem that can occur if the initial pressure in an Otto cycle engine is too high?
Signup and view all the answers
How does the Diesel engine differ from the Otto engine in terms of ignition?
How does the Diesel engine differ from the Otto engine in terms of ignition?
Signup and view all the answers
What does the term 'four-stroke engine' refer to?
What does the term 'four-stroke engine' refer to?
Signup and view all the answers
What key role does the intake manifold play in the functioning of an engine?
What key role does the intake manifold play in the functioning of an engine?
Signup and view all the answers
What occurs during the delay period in a compression ignition engine?
What occurs during the delay period in a compression ignition engine?
Signup and view all the answers
What are the two parts into which the ignition delay period can be divided?
What are the two parts into which the ignition delay period can be divided?
Signup and view all the answers
Which of the following factors affects the rate of vaporization of fuel droplets in a compression ignition engine?
Which of the following factors affects the rate of vaporization of fuel droplets in a compression ignition engine?
Signup and view all the answers
Which stage follows the ignition delay in the combustion process of a C.I. engine?
Which stage follows the ignition delay in the combustion process of a C.I. engine?
Signup and view all the answers
What is the range of ignition delay for low-compression ratio direct injection (DI) diesel engines?
What is the range of ignition delay for low-compression ratio direct injection (DI) diesel engines?
Signup and view all the answers
Which of these is NOT a requirement for good atomization during fuel injection?
Which of these is NOT a requirement for good atomization during fuel injection?
Signup and view all the answers
During which phase does the fuel continue to burn even after injection ceases?
During which phase does the fuel continue to burn even after injection ceases?
Signup and view all the answers
Which process occurs first during the ignition delay period after fuel injection?
Which process occurs first during the ignition delay period after fuel injection?
Signup and view all the answers
What does the relative efficiency or efficiency ratio (ηr) represent?
What does the relative efficiency or efficiency ratio (ηr) represent?
Signup and view all the answers
Which of the following factors influences volumetric efficiency?
Which of the following factors influences volumetric efficiency?
Signup and view all the answers
What is the ideal air to fuel ratio (A/F ratio) in spark-ignition engines for optimal performance?
What is the ideal air to fuel ratio (A/F ratio) in spark-ignition engines for optimal performance?
Signup and view all the answers
How does a lean air/fuel mixture affect engine performance?
How does a lean air/fuel mixture affect engine performance?
Signup and view all the answers
What happens when the air/fuel mixture becomes too weak?
What happens when the air/fuel mixture becomes too weak?
Signup and view all the answers
Which component is NOT typically included in a heat balance sheet for engine performance analysis?
Which component is NOT typically included in a heat balance sheet for engine performance analysis?
Signup and view all the answers
What does a compression ratio indicate in an engine?
What does a compression ratio indicate in an engine?
Signup and view all the answers
Which of the following describes the effect of a rich air/fuel mixture on engine performance?
Which of the following describes the effect of a rich air/fuel mixture on engine performance?
Signup and view all the answers
What does the brake specific fuel consumption (bsfc) measure?
What does the brake specific fuel consumption (bsfc) measure?
Signup and view all the answers
How is the indicated specific fuel consumption (isfc) defined?
How is the indicated specific fuel consumption (isfc) defined?
Signup and view all the answers
What does a lower specific fuel consumption indicate about engine efficiency?
What does a lower specific fuel consumption indicate about engine efficiency?
Signup and view all the answers
What is the mechanical efficiency of an engine calculated from?
What is the mechanical efficiency of an engine calculated from?
Signup and view all the answers
What is a common range for mechanical efficiency in engines?
What is a common range for mechanical efficiency in engines?
Signup and view all the answers
What are typical values of bsfc for naturally aspirated automobile engines?
What are typical values of bsfc for naturally aspirated automobile engines?
Signup and view all the answers
What constrains the combustion efficiency in an engine during a cycle?
What constrains the combustion efficiency in an engine during a cycle?
Signup and view all the answers
In SI units, how is brake specific fuel consumption (bsfc) expressed?
In SI units, how is brake specific fuel consumption (bsfc) expressed?
Signup and view all the answers
What causes knock in compression ignition (CI) engines?
What causes knock in compression ignition (CI) engines?
Signup and view all the answers
How does Homogeneous Charge Compression Ignition (HCCI) differ from traditional spark ignition engines?
How does Homogeneous Charge Compression Ignition (HCCI) differ from traditional spark ignition engines?
Signup and view all the answers
What is a characteristic feature of the combustion process in HCCI engines?
What is a characteristic feature of the combustion process in HCCI engines?
Signup and view all the answers
Which of the following is an advantage of HCCI combustion?
Which of the following is an advantage of HCCI combustion?
Signup and view all the answers
What is the primary method of combustion initiation in HCCI engines?
What is the primary method of combustion initiation in HCCI engines?
Signup and view all the answers
What is one of the disadvantages of HCCI combustion?
What is one of the disadvantages of HCCI combustion?
Signup and view all the answers
What effect does using very lean mixtures in HCCI engines have on emissions?
What effect does using very lean mixtures in HCCI engines have on emissions?
Signup and view all the answers
Which fuel types can HCCI engines operate on?
Which fuel types can HCCI engines operate on?
Signup and view all the answers
Study Notes
Introduction to Heat Engines
- A heat engine is any type of engine or machine that takes heat energy from the combustion of fuel and converts this energy into mechanical work.
- Heat engines can be grouped into two main classes: external and internal combustion engines.
External Combustion Engines
- Combustion of fuel occurs outside the cylinder, such as in steam engines.
- Heat from combustion generates steam which powers a piston or turbine.
- Examples include steam turbines and gas turbines.
- Often used for locomotives, ships, and generating electricity.
- Advantages over internal combustion engines: cheaper fuels (including solids), high starting torque, self-starting with working fluid, flexible arrangement.
Internal Combustion Engines
- Combustion of fuel occurs inside the cylinder.
- Fuel mixes with oxygen in the air inside the engine cylinder.
- Engines using mixtures of combustible gases and air are called gas engines.
- Engines using lighter liquid fuels (e.g., petrol) are called petrol engines.
- Engines using heavier liquid fuels (e.g., oil) are called compression ignition engines or diesel engines.
- Commonly used in road vehicles, aircraft, locomotives, and industrial applications.
Advantages of Reciprocating Internal Combustion Engines
- Higher overall efficiency
- Greater mechanical simplicity
- Easy starting from cold conditions
- Lower weight to power ratio
- Lower initial cost
- Compact units, requiring less space
Principles of Internal Combustion Engines
- Conventional internal combustion engines have one or more cylinders in which combustion of the fuel takes place.
- Main cylinder parts include: cylinder head, valve stem, clearance volume, cylinder, bottom dead center, spark plug, inlet valve, air, fuel injector, exhaust valve, connecting rod, crankshaft, crank case, sump.
Engine Components
- Cylinder: Cylindrical container for piston movement.
- Cylinder Head: Top end of the cylinder, houses valves and spark plugs.
- Inlet and Exhaust Valves: Control air and exhaust flow.
- Piston: Transmits combustion force to connecting rod.
- Connecting Rod: Connects piston to crankshaft.
- Crank Shaft: Rotates to produce rotational energy.
- Crankcase: Main engine body housing crankshaft, and bearings.
- Flywheel: A large wheel mounted on the crankshaft to maintain constant speed.
Cylinder Geometry
- Cylinder Bore (D): Inner diameter of the cylinder.
- Piston Area (A): Area of a circle with a diameter equal to the bore.
- Stroke (L): Linear distance of piston travel.
- Bore Stroke Ratio: Ratio of bore to stroke.
- Square: Equal bore and stroke.
- Over-square: Stroke shorter than bore.
- Under-square: Stroke longer than bore.
Engine Classifications
- Based on ignition type (spark ignition or compression ignition).
- Based on number of strokes per cycle (two-stroke or four-stroke).
- Based on application (automotive, marine, etc.).
Working Cycle
- Four-stroke: intake, compression, power, exhaust.
- Two-stroke: much simpler but less efficient than four-stroke.
- Supercharging/Turbocharging: increase air density for higher power output.
- Mechanical supercharger: Driven by engine crankshaft.
- Turbocharger: Turbine driven by exhaust gases.
Valve Location
- Valve in block, L head: Older applications.
- Valve in head, I head: Standard for modern automobiles.
- One valve in head and one in block, F head: Less common.
- Valves in block on opposite sides of cylinder, T head.
Fuel Used
- Gasoline (petrol)
- Fuel oil (diesel fuel)
- Natural gas
- Liquid petroleum gas
- Alcohols (e.g., methanol, ethanol)
- Hydrogen
Method of Mixture Preparation
- Carburetor
- Fuel injection into intake ports/manifold
- Fuel injection into the engine cylinder
Method of Ignition
- Spark ignition: Spark plug initiates combustion.
- Compression ignition: Fuel self-ignites due to high compression temperatures.
Combustion Chamber Design
- Shape of combustion chamber impacts knock and performance.
- Used in connection with spark ignition engines.
Method of Load Control
- Throttling of fuel/air flow.
- Control of fuel flow alone.
Method of Cooling
- Water cooled
- Air cooled
Engine Cycles
- Otto Cycle: Four-stroke, spark ignition.
- Diesel Cycle: Four-stroke, compression ignition.
- Dual Cycle
Engine Performance
- Evaluating engine performance depends on measures.
- Specific fuel consumption (brake and indicated)
- Brake mean effective pressure
- Specific power output, specific weight, exhaust smoke, other emissions.
Additional Notes
- Many different types of internal combustion engines exist with various characteristics and applications.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on internal combustion engines with this quiz. It covers important concepts such as horsepower, brake power, and the functions of various engine strokes. Perfect for students studying mechanical engineering or automotive technology.