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Questions and Answers
What does the term 'imep' primarily represent in terms of engine cycles?
What does the term 'imep' primarily represent in terms of engine cycles?
Which formula correctly defines brake fuel conversion efficiency?
Which formula correctly defines brake fuel conversion efficiency?
What is the primary significance of a low specific fuel consumption (sfc) value?
What is the primary significance of a low specific fuel consumption (sfc) value?
What aspect does the Air/Fuel ratio influence in engine operation?
What aspect does the Air/Fuel ratio influence in engine operation?
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What does the term QLHV represent in engine efficiency calculations?
What does the term QLHV represent in engine efficiency calculations?
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What is defined as the difference in volume between maximum and minimum in an engine chamber?
What is defined as the difference in volume between maximum and minimum in an engine chamber?
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Which term describes the volume at the lowest position of the piston?
Which term describes the volume at the lowest position of the piston?
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How is the volumetric compression ratio (rc) calculated in an internal combustion engine?
How is the volumetric compression ratio (rc) calculated in an internal combustion engine?
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In relation to the crank mechanism, what does the term 'stroke' refer to?
In relation to the crank mechanism, what does the term 'stroke' refer to?
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What is the function of the crankshaft in an internal combustion engine?
What is the function of the crankshaft in an internal combustion engine?
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Which component is directly responsible for converting the pressure from combustion into torque?
Which component is directly responsible for converting the pressure from combustion into torque?
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What is the primary characteristic of a spark ignition (SI) engine?
What is the primary characteristic of a spark ignition (SI) engine?
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Which of the following is NOT a classification criterion for internal combustion engines (ICEs)?
Which of the following is NOT a classification criterion for internal combustion engines (ICEs)?
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Which factor is crucial for fuel ignition in CI engines?
Which factor is crucial for fuel ignition in CI engines?
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What distinguishes a four-stroke engine from a two-stroke engine?
What distinguishes a four-stroke engine from a two-stroke engine?
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What happens during the intake phase of a four-stroke engine?
What happens during the intake phase of a four-stroke engine?
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How does the compression ratio of CI engines typically compare to SI engines?
How does the compression ratio of CI engines typically compare to SI engines?
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What is the primary reason for not pre-mixing fuel with air in CI engines?
What is the primary reason for not pre-mixing fuel with air in CI engines?
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In the context of diesel engines, what action is sufficient to reduce power output?
In the context of diesel engines, what action is sufficient to reduce power output?
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What defines the combustion process in a CI engine?
What defines the combustion process in a CI engine?
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What primarily affects the cycle duration in an engine?
What primarily affects the cycle duration in an engine?
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What does the term $\alpha$ represent in the context of fuel and air ratios?
What does the term $\alpha$ represent in the context of fuel and air ratios?
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In the equation defining the stoichiometric ratio, what do the variables $a$ and $b$ represent?
In the equation defining the stoichiometric ratio, what do the variables $a$ and $b$ represent?
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What role does the controlled charge valve play in a two-stroke engine?
What role does the controlled charge valve play in a two-stroke engine?
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What typical value is the stoichiometric ratio for gasoline and diesel approximately?
What typical value is the stoichiometric ratio for gasoline and diesel approximately?
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Which of the following statements about two-stroke and four-stroke engines is true?
Which of the following statements about two-stroke and four-stroke engines is true?
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Which parameter is used to measure how effective an engine is at removing burnt gases?
Which parameter is used to measure how effective an engine is at removing burnt gases?
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How does the crankcase function as a compressor in a two-stroke engine?
How does the crankcase function as a compressor in a two-stroke engine?
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What is the relationship of $\alpha$ to $\alpha_{st}$ when considering the Air/Fuel ratio?
What is the relationship of $\alpha$ to $\alpha_{st}$ when considering the Air/Fuel ratio?
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Why are two-stroke engines not commonly used in automotive applications?
Why are two-stroke engines not commonly used in automotive applications?
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What does the energy parameter $QLHV \cdot \alpha_{st}$ represent?
What does the energy parameter $QLHV \cdot \alpha_{st}$ represent?
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Which characteristic of hydrogen affects its energy parameter compared to other fuels?
Which characteristic of hydrogen affects its energy parameter compared to other fuels?
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Which classification criterion for internal combustion engines (ICEs) refers to the absence of a mechanical air delivery system?
Which classification criterion for internal combustion engines (ICEs) refers to the absence of a mechanical air delivery system?
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Why is volumetric efficiency specifically applied to four-stroke engines?
Why is volumetric efficiency specifically applied to four-stroke engines?
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In what scenario is a two-stroke engine most commonly utilized?
In what scenario is a two-stroke engine most commonly utilized?
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What is a significant disadvantage of two-stroke engines compared to four-stroke engines?
What is a significant disadvantage of two-stroke engines compared to four-stroke engines?
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What effect does using a Roots compressor or turbocompressor have in an ICE?
What effect does using a Roots compressor or turbocompressor have in an ICE?
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What characterizes pumping work in naturally aspirated engines?
What characterizes pumping work in naturally aspirated engines?
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How does exhaust gas recirculation (EGR) affect pumping work in supercharged or turbocharged engines?
How does exhaust gas recirculation (EGR) affect pumping work in supercharged or turbocharged engines?
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Which of the following best describes indicated power?
Which of the following best describes indicated power?
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What does mechanical efficiency represent in an engine's performance?
What does mechanical efficiency represent in an engine's performance?
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What is the significance of mean effective pressure (MEP) in engine performance analysis?
What is the significance of mean effective pressure (MEP) in engine performance analysis?
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Under what condition does mechanical efficiency become zero?
Under what condition does mechanical efficiency become zero?
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In the context of engine work cycles, what does the term 'pumping work' refer to?
In the context of engine work cycles, what does the term 'pumping work' refer to?
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Which of the following statements about indicated power (Pi) is incorrect?
Which of the following statements about indicated power (Pi) is incorrect?
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Study Notes
Internal Combustion Engines (ICE)
- Engines convert chemical energy of fuel into mechanical energy at a rotating shaft.
- Lower Heating Value (LHV) is a specific fuel value, measured in a lab.
- Brake (b) value is determined by measuring engine's torque or power connected to a brake.
Internal vs. External Combustion
- Internal Combustion Engines (ICE): Combustion happens inside the machine, changing fluid properties.
- External Combustion Engines (ECE): Combustion occurs in a separate chamber (burner), and the working fluid doesn't directly combust, only changing temperatures. Examples: Stirling and steam engines. Note that turbines though use burners, the fluid does change properties.
Reciprocating Engines
- Made up of cylinders where a piston moves up and down.
- Crank-slide mechanism connects the piston to the crankshaft (shaft).
- Connecting rod (con-rod) connects the piston to the crankshaft.
- Top Dead Centre (TDC) is the piston's highest position, and Bottom Dead Centre (BDC) is the lowest.
- Clearance volume (Ve) is the minimum volume, and displacement (Va) is the difference between maximum and minimum volume.
Classification of IC Engine Types
- Rotary (e.g. Wankel) engines have limited automotive applications.
- Reciprocating engines are used more widely.
ICE Classification Criteria
- Method of Ignition: Spark ignition (SI) engines use a spark plug to ignite a pre-mixed air-fuel charge, while compression ignition (CI) engines ignite a compressed, injected fuel.
- Cycle Duration: Two-stroke engines complete a cycle in one revolution, while four-stroke engines need two revolutions.
Main Components (SI Engine)
- Cylinders
- Pistons
- Connecting rods
- Crankshafts
- Spark plugs
- Valves (intake and exhaust)
Other Classification Criteria
- Air supply (naturally aspirated, supercharged, turbocharged).
- Mixture preparation (carburetor, port fuel injection, direct fuel injection)
- Cooling method (liquid cooling, air cooling).
- Engine shape (in-line, V-engines, opposed cylinder).
ICE Performance
- Performance assessed on a range of operating speeds.
- Maximum power is a key performance metric that is associated to the full engine loading condition.
- Torque, power, and engine speed are important for analysis.
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Description
Explore the fundamentals of Internal Combustion Engines (ICE) and how they convert fuel into mechanical energy. Learn about the key concepts such as Lower Heating Value (LHV), the differences between internal and external combustion, and the workings of reciprocating engines. Test your understanding through this engaging quiz.
