Vapor Power Cycles: Master Thermodynamics with Online Quizzes

Question 1

In a Rankine cycle, what is the theoretical maximum efficiency achievable?

Accepted Answer

Carnot's efficiency

Answer

100%

Answer

50%

Answer

Lower than Carnot's efficiency

Question 2

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

Accepted Answer

To convert steam into liquid

Answer

To cool the steam

Answer

To increase the steam pressure

Answer

To remove impurities from the steam

Question 3

Which of the following factors has the most significant influence on the thermal efficiency of a Rankine cycle?

Accepted Answer

Turbine inlet temperature

Answer

Condenser pressure

Answer

Pump work input

Answer

Heat source temperature

Question 4

In a Rankine cycle, what is the primary function of a reheater?

Accepted Answer

To increase the steam temperature before expansion in the turbine

Answer

To decrease the steam moisture content

Answer

To improve the thermal efficiency

Answer

To prevent damage to the turbine

Question 5

Which type of turbine is predominantly used in vapor power plants?

Accepted Answer

Axial turbine

Answer

Radial turbine

Answer

Pelton turbine

Answer

Francis turbine

Question 6

What is the significance of the critical pressure in a Rankine cycle?

Accepted Answer

It is the pressure at which the steam becomes supercritical

Answer

It determines the maximum efficiency achievable

Answer

It is the pressure at which the steam completely condenses

Answer

It has no significant impact on the cycle

Question 7

What is the primary advantage of utilizing a regenerative cycle instead of a simple Rankine cycle?

Accepted Answer

Enhanced thermal efficiency

Answer

Reduced turbine work

Answer

Increased condenser pressure

Answer

Lower pump work

Question 8

Which component is absent in a Rankine cycle?

Accepted Answer

Compressor

Answer

Boiler

Answer

Turbine

Answer

Pump

Question 9

Vapor power cycles typically employ which type of turbine?

Accepted Answer

Steam turbine

Answer

Pelton turbine

Answer

Kaplan turbine

Answer

Impulse turbine

Question 10

How does increasing boiler pressure affect a Rankine cycle's efficiency?

Accepted Answer

Increases efficiency

Answer

Decreases efficiency

Answer

Has no effect on efficiency

Answer

Efficiency is proportional to the square of boiler pressure

Question 11

Which advantage does reheating offer in a vapor power cycle?

Accepted Answer

Enhances cycle efficiency

Answer

Reduces turbine blade erosion

Answer

Increases condenser pressure

Answer

Reduces boiler size

Question 12

For a Carnot heat engine operating between fixed temperatures, what is the ideal cycle efficiency?

Accepted Answer

1 - (T_L / T_H)

Answer

(T_H - T_L) / T_H

Answer

T_H / (T_H - T_L)

Answer

T_L / (T_H - T_L)

Question 13

What is the primary purpose of a feedwater heater in a vapor power cycle?

Accepted Answer

Improving cycle efficiency

Answer

Enhancing boiler efficiency

Answer

Reducing turbine blade erosion

Answer

Reducing condenser pressure

Question 14

Which characteristic defines a supercritical vapor power cycle?

Accepted Answer

Boiler pressure exceeding critical pressure

Answer

Absence of phase change in the boiler

Answer

Turbine inlet temperature lower than in subcritical cycles

Answer

Reduced pumping power requirement

Question 15

Which of the following is NOT a crucial component of a canonical Rankine cycle?

Accepted Answer

Generator

Answer

Boiler

Answer

Turbine

Answer

Condenser

Question 16

What is the primary advantage of employing steam reheating in a Rankine cycle?

Accepted Answer

Enhanced turbine efficiency

Answer

Diminished condenser dimensions

Answer

Increased boiler pressure

Answer

Improved condenser heat transfer

Question 17

In a Rankine cycle, the process where water transforms from a liquid to a vapor is termed:

Accepted Answer

Evaporation

Answer

Condensation

Answer

Expansion

Answer

Compression

Question 18

Employing supercritical steam in a Rankine cycle offers which benefit?

Accepted Answer

Elevated thermal efficiency

Answer

Reduced condenser size

Answer

Extended turbine blade lifespan

Answer

Enhanced heat transfer in the boiler

Question 19

The isentropic efficiency of a turbine measures the ratio of:

Accepted Answer

Actual work output to isentropic work output

Answer

Isentropic work output to actual work output

Answer

Actual efficiency to Carnot efficiency

Answer

Carnot efficiency to actual efficiency

Question 20

What is the primary function of a condenser in a vapor power cycle?

Accepted Answer

To reject heat to the environment

Answer

To absorb heat from the environment

Answer

To increase the pressure of the working fluid

Answer

To decrease the temperature of the working fluid

Question 21

What is the main benefit of a reheat cycle compared to a simple Rankine cycle?

Accepted Answer

Increased cycle efficiency

Answer

Higher turbine efficiency

Answer

Lower condenser pressure

Answer

Reduced boiler size

Question 22

Which of the following is a type of topping cycle commonly used to enhance the efficiency of vapor power cycles?

Accepted Answer

Gas turbine cycle

Answer

Diesel cycle

Answer

Stirling cycle

Answer

Otto cycle

Question 23

What is the fundamental purpose of a feedwater heater in a vapor power cycle?

Accepted Answer

To heat the feedwater using extracted steam

Answer

To cool the feedwater using condenser water

Answer

To increase the pressure of the feedwater

Answer

To remove impurities from the feedwater

Question 24

The fundamental difference between a subcritical and a supercritical Rankine cycle lies in:

Accepted Answer

The pressure and temperature of the working fluid at the turbine inlet

Answer

The type of condenser used

Answer

The efficiency of the cycle

Answer

The number of stages in the turbine

Question 25

What is the theoretical maximum efficiency of a Rankine cycle, assuming no irreversibilities?

Accepted Answer

100%

Answer

75%

Answer

50%

Answer

25%

Question 26

Which of the following factors does NOT affect the thermal efficiency of a vapor power cycle?

Accepted Answer

Pump power

Answer

Turbine efficiency

Answer

Boiler pressure

Answer

Condenser temperature

Question 27

What is the significance of the 'pinch point' in the temperature-entropy diagram of a vapor power cycle?

Accepted Answer

It represents the minimum temperature difference in the heat exchanger.

Answer

It determines the maximum potential efficiency of the cycle.

Answer

It indicates the pressure drop across the condenser.

Answer

It is the point where the working fluid changes phase.

Question 28

Which type of turbine is typically used in vapor power cycles?

Accepted Answer

Reaction turbine

Answer

Impulse turbine

Answer

Pelton turbine

Answer

Francis turbine

Question 29

What is the main advantage of a combined cycle power plant compared to a conventional steam power plant?

Accepted Answer

Higher thermal efficiency

Answer

Reduced emissions

Answer

Lower operating costs

Answer

Increased plant flexibility

Question 30

What is the purpose of the turbine in a vapor power cycle?

Accepted Answer

To convert thermal energy into mechanical energy

Answer

To condense the working fluid

Answer

To add heat to the cycle

Answer

To increase the pressure of the working fluid

Question 31

Which type of turbine is primarily utilized in vapor power cycles?

Accepted Answer

Steam turbine

Answer

Gas turbine

Answer

Hydraulic turbine

Answer

Wind turbine

Question 32

What is the fundamental measure of a vapor power cycle's performance?

Accepted Answer

Thermal efficiency

Answer

Condenser pressure

Answer

Power output

Answer

Heat input

Question 33

Identify the primary distinction between a reheat and a regenerative cycle.

Accepted Answer

Reheat cycle involves reheating steam between turbine stages, while a regenerative cycle employs extracted steam for feed water preheating.

Answer

Reheat cycle uses higher pressure steam, while a regenerative cycle uses lower pressure steam.

Question 34

Which substance serves as the primary working fluid in vapor power cycles?

Accepted Answer

Water

Answer

Helium

Answer

Carbon dioxide

Answer

Ammonia

Question 35

What is the fundamental advantage offered by combined cycle power plants?

Accepted Answer

Elevated efficiency

Answer

Reduced emissions

Answer

Lower operating costs

Answer

Enhanced reliability

Question 36

Identify a key drawback associated with vapor power cycles.

Accepted Answer

Elevated capital costs

Answer

Intricate operation

Answer

Lower efficiency

Answer

Restricted fuel adaptability

Question 37

What is the primary purpose of reheating in a Rankine cycle?

Accepted Answer

To improve thermal efficiency by reducing the moisture content of the steam entering the turbine.

Answer

To reduce pump work by increasing the specific volume of the steam.

Answer

To decrease condenser pressure by reducing the condenser heat transfer area.

Answer

To increase turbine power by providing a higher mass flow rate.

Question 38

Which of the following factors has a direct impact on the efficiency of the Rankine cycle?

Accepted Answer

Turbine inlet temperature

Answer

Condenser size

Answer

Pump speed

Answer

Ambient temperature

Question 39

Distinguish between saturated steam and superheated steam.

Accepted Answer

Saturated steam is at its boiling point for a given pressure, while superheated steam is at a higher temperature than its saturation temperature.

Answer

Superheated steam is at its boiling point for a given pressure, while saturated steam is at a higher temperature than its saturation temperature.

Question 40

What is the main advantage of using a regenerative Rankine cycle?

Accepted Answer

Improved thermal efficiency due to preheating the feedwater before it enters the boiler.

Answer

Increased boiler pressure due to higher steam temperatures.

Answer

Reduced turbine power due to lower steam flow rates.

Answer

Decreased condenser size due to reduced heat transfer requirements.

Question 41

Identify the major application of vapor power cycles.

Accepted Answer

Power generation in thermal power plants.

Answer

Air conditioning for residential and commercial buildings.

Answer

Refrigeration systems in industrial processes.

Answer

Space heating in district heating systems.

Question 42

Differentiate between a wet steam turbine and a dry steam turbine.

Accepted Answer

A wet steam turbine operates with steam containing moisture droplets, while a dry steam turbine operates with superheated steam.

Answer

A dry steam turbine operates with steam containing moisture droplets, while a wet steam turbine operates with superheated steam.

Question 43

Describe a challenge associated with utilizing vapor power cycles.

Accepted Answer

Corrosion and erosion of system components due to the presence of steam and high temperatures.

Answer

The limited availability of suitable working fluids for use in vapor power cycles.

Answer

The high capital cost of constructing and maintaining vapor power plants.