Power Cycles and Heat Engines: Interactive Learning Quizzes

Question 1

What is the maximum theoretical efficiency of a heat engine operating between two fixed temperature reservoirs?

Accepted Answer

1 - (T_L/T_H)

Answer

T_H - T_L

Answer

(T_H - T_L)/T_H

Answer

T_H/(T_H - T_L)

Question 2

What is the definition of the compression ratio of a reciprocating engine?

Accepted Answer

Ratio of the maximum to minimum volume of the working fluid in the cylinder

Answer

Ratio of the minimum to maximum volume of the working fluid in the cylinder

Answer

Ratio of the maximum pressure to minimum pressure of the working fluid in the cylinder

Answer

Ratio of the minimum pressure to maximum pressure of the working fluid in the cylinder

Question 3

What is the primary function of a condenser in a Rankine cycle?

Accepted Answer

To reject heat to the environment

Answer

To add heat to the working fluid

Answer

To compress the working fluid

Answer

To expand the working fluid

Question 4

Which of the following factors does NOT affect the efficiency of a heat engine?

Accepted Answer

Ambient temperature

Answer

Heat transfer rate

Answer

Friction

Answer

Working fluid properties

Question 5

What is the ideal gas equation?

Accepted Answer

PV = nRT

Answer

PV = RT

Answer

PV = nR

Answer

PV = RTn

Question 6

What is the specific heat capacity of a substance?

Accepted Answer

Amount of heat required to raise the temperature of 1 unit mass of a substance by 1 unit temperature

Answer

Amount of heat required to raise the temperature of 1 unit volume of a substance by 1 unit temperature

Answer

Amount of heat required to convert 1 unit mass of a substance from a liquid to a gas

Answer

Amount of heat required to convert 1 unit volume of a substance from a solid to a liquid

Question 7

What is the primary function of a condenser in a Rankine cycle?

Accepted Answer

To convert high-pressure steam to low-pressure water

Answer

To convert low-pressure water to high-pressure steam

Answer

To cool the working fluid

Answer

To heat the working fluid

Question 8

What is the key difference between a reversible and irreversible process?

Accepted Answer

Reversible processes can be reversed without any change in entropy, while irreversible processes cannot.

Answer

Irreversible processes can be reversed without any change in entropy, while reversible processes cannot.

Answer

Reversible processes involve no friction, while irreversible processes do.

Answer

Irreversible processes involve no friction, while reversible processes do.

Question 9

What is the relationship between entropy and molecular disorder?

Accepted Answer

Entropy is directly proportional to molecular disorder.

Answer

Entropy is inversely proportional to molecular disorder.

Answer

Entropy is not related to molecular disorder.

Answer

The relationship depends on the system being considered.

Question 10

In a gas turbine cycle, what is the primary function of an intercooler?

Accepted Answer

Decrease compressor work input

Answer

Increase compressor work output

Answer

Increase turbine work output

Answer

Decrease turbine work input

Question 11

Which of the following is not a crucial component of a vapor power cycle?

Accepted Answer

Compressor

Answer

Boiler

Answer

Condenser

Answer

Turbine

Question 12

The efficiency of a reversible heat engine, operating between two heat reservoirs at different temperatures, is given by:

Accepted Answer

Temperature difference between reservoirs / Temperature of hot reservoir

Answer

Temperature difference between reservoirs / Temperature of cold reservoir

Answer

Temperature of hot reservoir / Temperature of cold reservoir

Answer

Temperature of cold reservoir / Temperature of hot reservoir

Question 13

Friction is an example of which type of process?

Accepted Answer

Irreversible

Answer

Isothermal

Answer

Adiabatic

Answer

Isobaric

Question 14

What is the significant difference between an open power cycle and a closed power cycle?

Accepted Answer

Open cycles exchange mass with the surroundings, while closed cycles do not.

Answer

Closed cycles exchange heat with the surroundings, while open cycles do not.

Answer

Open cycles operate at higher temperatures than closed cycles.

Answer

Closed cycles are more efficient than open cycles.

Question 15

How does the thermal efficiency (η) of a heat engine change as the amount of heat rejected (Qout) increases?

Accepted Answer

η decreases as Qout increases

Answer

η increases as Qout increases

Answer

η increases exponentially as Qout increases

Answer

η decreases exponentially as Qout increases

Question 16

Advanced power cycles, such as combined cycle or cogeneration systems, are known for their:

Accepted Answer

Increased efficiency by combining cycles or utilizing waste heat

Answer

Reduced emissions through advanced combustion techniques

Answer

Lower operating costs due to optimized designs and fuel flexibility

Answer

Enhanced reliability from redundant components and advanced control systems

Question 17

Which of the following is an essential property of a reversible heat engine?

Accepted Answer

Operates without friction

Answer

Undergoes irreversible processes

Answer

Releases heat to the environment

Answer

Operates at a constant temperature

Question 18

What is the primary purpose of an evaporator in a refrigeration cycle?

Accepted Answer

To absorb heat from a cold reservoir

Answer

To expand refrigerant

Answer

To compress refrigerant

Answer

To reject heat to a hot reservoir

Question 19

What component in a gas turbine engine is responsible for extracting mechanical energy from the hot gas stream?

Accepted Answer

Turbine

Answer

Combustor

Answer

Compressor

Answer

Heat exchanger

Question 20

What is the primary advantage of using a regenerative heat exchanger in a Brayton cycle?

Accepted Answer

Improves thermal efficiency by recovering waste heat

Answer

Reduces emissions

Answer

Increases power output

Answer

Lowers engine temperature

Question 21

Which of the following is NOT a fundamental component of a simple power cycle?

Accepted Answer

Condenser

Answer

Heat source

Answer

Turbine

Answer

Working fluid

Question 22

In a Carnot cycle, the isothermal heat rejection process occurs at which reservoir?

Accepted Answer

Lower temperature reservoir

Answer

Higher temperature reservoir

Answer

Adiabatic expansion

Question 23

Which factor does NOT influence the theoretical efficiency of a heat engine?

Accepted Answer

Ambient temperature

Answer

Temperature of heat sink

Answer

Temperature of heat source

Answer

Type of working fluid

Question 24

Which is an advantage of a diesel engine over a gasoline engine?

Accepted Answer

Higher thermal efficiency

Answer

Quieter operation

Answer

Lower emissions

Answer

Faster acceleration

Question 25

In a Rankine cycle, the main purpose of the condenser is to:

Accepted Answer

Convert steam to liquid

Answer

Generate steam

Answer

Expand steam

Answer

Compress steam

Question 26

Which of the following is a typical application of a turbojet engine?

Accepted Answer

Aircraft propulsion

Answer

Automotive transportation

Answer

Refrigeration

Answer

Power generation