Mechanical Engineering MCQs – Combined Cycle Power Generation ( Power Plant Engineering ) MCQs

Mechanical Engineering MCQs – Combined Cycle Power Generation ( Power Plant Engineering ) MCQs

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Mechanical Engineering MCQs – Combined Cycle Power Generation ( Power Plant Engineering ) MCQs

The most occurred mcqs of ( ) in past papers. Past papers of Combined Cycle Power Generation ( Power Plant Engineering ) Mcqs. Past papers of Combined Cycle Power Generation ( Power Plant Engineering ) Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Combined Cycle Power Generation ( Power Plant Engineering ) Mcqs. The Important series of Combined Cycle Power Generation ( Power Plant Engineering ) Mcqs are given below:

Flaws of Steam as a Working Fluid and Vapor Cycle Characteristics

1. Addition of an infinitesimal amount of heat at the highest temperature is because ___________
a) to initiate reheating
b) to initiate regeneration
c) to initiate superheating
d) none of the mentioned
Answer: c
Explanation: The maximum temperature gained in steam cycles using the best available material is about 600 degree Celsius while the critical temperature of steam is about 375 degree Celsius, which necessitates large superheating and permits addition of an infinitesimal amount of heat at the highest temperature.

2. High moisture content is involved during expansion of steam because ___________
a) to ensure uniform heating
b) to ensure uniform cooling
c) to obtain a higher temperature of heat addition
d) to obtain a lower temperature of heat addition
Answer: c
Explanation: In order to obtain a higher temperature of heat addition, heat moisture content is involved during expansion of steam.

3. What is the relation of the mean temperature of heat addition and cycle efficiency?
a) both are inversely proportional
b) both are directly proportional
c) both are independent of each other
d) none of the mentioned
Answer: b
Explanation: The cycle efficiency is a function of mean temperature of heat addition. Hence, both are directly proportional to each other. The need for high pressure is only forced due to weak characteristics of steam.

4. Temperature of heat rejection in a condenser can be lowered by using?
a) lubricant
b) oil
c) refrigerant
d) diesel
Answer: c
Explanation: A refrigerant in the form of coolant is used to lower the temperature of heat rejection.

5. The use of which of the following becomes necessary during expansion of steam?
a) reheat
b) regeneration
c) refrigeration
d) superheat
Answer: a
Explanation: In order to obtain a higher temperature of heat addition, heat moisture content is involved during expansion of steam. The use of reheat thus becomes necessary.

6. Which is the drawback of the steam as a working substance in a power cycle?
a) in a vapour power cycle, maximum temperature which can be obtained with best available material is more than the critical temperature of water and requires large superheating
b) it allows only small amount of heat addition at the highest temperature
c) it requires reheat and reheater tubes are costly
d) all of the mentioned
Answer: d
Explanation: All the drawbacks mentioned are correct.

7. For maximum efficiency of vapour power cycle, what should be the critical temperature of working fluid?
a) the working fluid should have critical temperature as low as possible
b) the working fluid should have critical temperature as high as possible
c) the critical temperature does not affect the efficiency of the vapour power cycle
d) none of the mentioned
Answer: b
Explanation: More the critical temperature, more efficient will be the working.

8. What is the specific heat of the ideal working fluid used in vapour power cycle?
a) should be constant
b) should be large
c) should be small
d) none of the mentioned
Answer: c
Explanation: The specific heat of a fluid is the amount of energy the fluid takes in heating water for 1 degree Celsius.

9. What is the importance of the freezing point of the working fluid in the vapour power cycle?
a) freezing point of working fluid should be below the room temperature
b) freezing point of working fluid should be above the room temperature
c) freezing point of working fluid should be equal to the room temperature
d) does not have any importance
Answer: a
Explanation: For the efficient working of a working fluid, its freezing point should be below the room temperature.

10. When two vapour cycles are coupled in series and heat rejected by one is absorbed by another, the cycle is called as?
a) Dual vapour cycle
b) Binary vapour cycle
c) Coupled vapour cycle
d) None of the mentioned
Answer: b
Explanation: Binary vapour cycle is a cycle where two vapour cycles are coupled in series and heat rejected by one is absorbed by another.

11. The engines which are operating on gas power cycle are?
a) cyclic
b) non-cyclic
c) either cyclic or non-cyclic
d) none of the mentioned
Answer: c
Explanation: The cyclic nature is totally dependent on power cycle; it can be cyclic as well as non-cyclic depending on the gas power cycle.

Binary Vapour Cycle

1. Rankine cycle efficiency of a good steam power plant may be in the range of ___________
a) 15 to 20%
b) 35 to 45%
c) 70 to 80%
d) 90 to 95%
Answer: b
Explanation: The efficiency of a Rankine cycle lies in the range of 35-45 percent mostly.

2. Rankine cycle operating on low pressure limit of p1 and high pressure limit of p2 ___________
a) has higher thermal efficiency than the Carnot cycle operating between same pressure limits
b) has lower thermal efficiency than Carnot cycle operating between same pressure limits
c) has same thermal efficiency as Carnot cycle operating between same pressure limits
d) may be more or less depending upon the magnitudes of p1 and p2
Answer: a
Explanation: For two pressure limits, the thermal efficiency of a Rankine cycle is more than that of the Carnot cycle operating between the same pressure difference which is evident in the P-V diagrams of both the cycle.

3. Rankine efficiency of a steam power plant ___________
a) improves in summer as compared to that in winter
b) improves in winter as compared to that in summer
c) is unaffected by climatic conditions
d) none of the mentioned
Answer: b
Explanation: Rankine cycle efficiency depends upon condenser temperature.

4. Rankine cycle comprises of ___________
a) two isentropic processes and two constant volume processes
b) two isentropic processes and two constant pressure processes
c) two isothermal processes and two constant pressure processes
d) none of the mentioned
Answer: b
Explanation: A rankine cycle is a thermodynamic cycle which comprises of two isentropic and two isobaric processes which is a major thermodynamic cycle in various applications.

5. In Rankine cycle the work output from the turbine is given by ___________
a) change of internal energy between inlet and outlet
b) change of enthalpy between inlet and outlet
c) change of entropy between inlet and outlet
d) change of temperature between inlet and outlet
Answer: b
Explanation: The power output from the turbine is given by the change of internal energy between inlet and outlet.

6. Regenerative heating i.e., bleeding steam to reheat feed water to boiler ___________
a) decreases thermal efficiency of the cycle
b) increases thermal efficiency of the cycle
c) does not affect thermal efficiency of the cycle
d) may increase or decrease thermal efficiency of the cycle depending upon the point of extraction of steam
Answer: b
Explanation: Bleeding decreases the thermal efficiency of the cycle as it reheats feed water to the boiler.

7. Regenerative cycle thermal efficiency ___________
a) is always greater than simple Rankine thermal efficiency
b) is greater than simple Rankine cycle thermal efficiency only when steam is bled at particular pressure
c) is same as simple Rankine cycle thermal efficiency
d) is always less than simple Rankine cycle thermal efficiency
Answer: a
Explanation: A regeneration is done to increase the efficiency of a reheat cycle so naturally the efficiency of a regenerative cycle is much more than a Rankine cycle.

8. In a regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating ___________
a) decreases with increase in Rankine cycle efficiency
b) increases with increase in Rankine cycle efficiency
c) is unaffected by increase in Rankine cycle efficiency
d) none of the mentioned
Answer: b
Explanation: In case of regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating decreases with increase in Rankine cycle efficiency. As the efficiency of regenerative cycle is more than the Rankine cycle.

9. In a regenerative feed heating cycle, the greatest economy is affected ___________
a) when steam is extracted from only one suitable point of steam turbine
b) when steam is extracted from several places in different stages of steam turbine
c) when steam is extracted only from the last stage of steam turbine
d) when steam is extracted only from the first stage of steam turbine
Answer: b
Explanation: Steam extraction is an important factor in deciding the economy of a regenerative cycle. The greatest economy is affected when steam is extracted from several places in different stages of steam turbine.

10. What is the maximum percentage gain in Regenerative feed heating cycle thermal efficiency?
a) increases with number of feed heaters increasing
b) decreases with number of feed heaters increasing
c) remains same unaffected by number of feed heaters
d) none of the mentioned
Answer: a
Explanation: In case of regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating decreases with increase in Rankine cycle efficiency. As the efficiency of regenerative cycle is more than the Rankine cycle. Naturally, the maximum percentage gain in regenerative feed heating cycle thermal efficiency increases with number of feed heaters increasing.

Binary Vapour Cycle – II

1. How can we differentiate Rankine cycle from Carnot cycle?
a) Heat addition process of Rankine cycle is reversible isothermal whereas heat addition process of Carnot cycle is reversible isobaric
b) Heat addition process of Rankine cycle is reversible isobaric whereas heat addition process of Carnot cycle is reversible isothermal
c) Heat addition process of Rankine cycle is reversible isentropic whereas heat addition process of Carnot cycle is reversible isothermal
d) Both cycles are identical except the working fluid used
Answer: b
Explanation: Heat addition process of Rankine cycle is reversible isobaric whereas heat addition process of Carnot cycle is reversible isothermal. This is one of the major differences in both the cycles.

2. What is the relation between efficiencies of Rankine cycle and Carnot cycle for the same pressure ratio?
a) (ηr) = (ηc)
b) (ηr) > (ηc)
c) (ηr) < (ηc)
d) none of the mentioned
Answer: c
Explanation: The relation between efficiencies of Rankine cycle and Carnot cycle for the same pressure ratio is given by,
r) < (ηc ).

3. If Tm be the mean temperature of heat addition in Rankine cycle as shown in diagram,
what will the formula for efficiency of Rankine cycle?
power-plant-questions-answers-freshers-q3
a) (ηr) = (T3 / Tm)
b) (ηr) = 1 – (T3 / Tm)
c) (ηr) = 1 – (T2 / Tm)
d) (ηr) = (T2 / Tm)
Answer: b
Explanation: The required formula becomes
r) = 1 – (T3 / Tm).

4. The maximum efficiency of Rankine cycle (ηr) is the function of ___________
a) the mean temperature of heat addition (Tm) only
b) the mean temperature of heat addition (Tm) and temperature of steam at the exit of the turbine
c) the mean temperature of heat addition (Tm) and temperature of steam at the entry of the turbine
d) the mean temperature of heat addition (Tm) and temperature of steam at exit of the condenser
Answer: a
Explanation: The maximum efficiency of Rankine cycle (ηr) is the function of
the mean temperature of heat addition (Tm) only.

5. What is the effect of superheated steam on efficiency of Rankine cycle?
a) efficiency of Rankine cycle decreases with increase in superheat of the steam
b) efficiency of Rankine cycle increases with increase in superheat of the steam
c) efficiency of Rankine cycle is not affected by change in superheat of the steam
d) none of the mentioned
Answer: b
Explanation: The effect of superheated steam on efficiency of Rankine cycle is that the efficiency of Rankine cycle increases with increase in superheat of the steam.

6. What is the effect of increase in pressure at which heat is added on the pump work in the Rankine cycle?
a) the pump work increases with increase in pressure of heat addition
b) the pump work decreases with increase in pressure of heat addition
c) the pump work does not change with increase in pressure of heat addition
d) the pump work either increases or decreases with increase in pressure of heat addition
Answer: a
Explanation: The effect of increase in pressure at which heat is added on the pump work in the Rankine cycle is that the pump work increases with increase in pressure of heat addition.

7. When the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust?
a) increases
b) decreases
c) remains same
d) cannot say
Answer: a
Explanation: With an increase in the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust increases.

 

Analysis Of Steam Engine MCQs

 

8. What is the condition for increasing the chances of corrosion of blades of turbine?
a) decrease in the pressure difference between which the Rankine cycle operates
b) increase in the pressure difference between which the Rankine cycle operates
c) increases and decreases in the pressure difference between which the Rankine cycle operates
d) none of the mentioned
Answer: b
Explanation: The condition for increasing the chances of corrosion of blades of turbine is an increase in the pressure difference between which the Rankine cycle operates.

9. What is the maximum content of moisture allowed at the turbine exhaust in the steam power plant?
a) 50 %
b) 60 %
c) 30 %
d) 15 %
Answer: d
Explanation: The maximum content of moisture allowed at the turbine exhaust in the steam power plant is 15 %.

10. Which of these is a binary cycle?
a) Mercury-steam cycle
b) Mercury-water cycle
c) Mercury-Sodium cycle
d) None of the mentioned
Answer: a
Explanation: The binary cycle is mainly a Mercury-Steam cycle.

Coupled Cycles

1. The mercury steam cycle represents how many coupled Rankine cycles?
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: The mercury steam cycle represents 2 fluid cycles where 2 Rankine cycles have been coupled in series.

2. In the mercury steam cycle, the mercury cycle is called?
a) bottoming cycle
b) middle cycle
c) topping cycle
d) none of the mentioned
Answer: c
Explanation: The mercury steam cycle has the mercury cycle as the topping cycle.

3. In the mercury steam cycle, the steam cycle is called?
a) bottoming cycle
b) middle cycle
c) topping cycle
d) none of the mentioned
Answer: a
Explanation: The mercury steam cycle has the steam cycle as the bottoming cycle.

4. Apart from mercury & steam, which of these is a component of tertiary cycle?
a) nitrogen di-oxide
b) water
c) carbon di-oxide
d) sulphur di-oxide
Answer: d
Explanation: The tertiary cycle is mercury-steam-sulphur dioxide cycle.

5. The addition of sulphur dioxide in a tertiary cycle is at?
a) high temperature
b) low temperature
c) too high temperature
d) none of the mentioned
Answer: b
Explanation: The tertiary cycle is mercury-steam-sulphur dioxide cycle. Here, addition of sulphur dioxide is at low temperature.

6. Which of these can also be used as a topping fluid?
a) Sodium
b) Calcium
c) Boron
d) Titanium
Answer: a
Explanation: Apart from mercury, only Sodium or Potassium are suitable enough to be used as a topping fluid.

7. Which of these can be used as a fluid in the bottoming fluid?
a) Mercury
b) Ammonia
c) Calcium
d) Sodium
Answer: b
Explanation: Apart from Sulphur dioxide, Ammonia is the most suitable bottoming fluid.

8. In case of Sodium-mercury-steam cycle, which is the topping fluid?
a) Mercury
b) Steam
c) Sodium
d) Cannot say
Answer: c
Explanation: Apart from mercury, only Sodium or Potassium are suitable enough to be used as a topping fluid. Here, mercury is not a topping fluid so naturally, sodium becomes the topping fluid.

9. In case of mercury-steam-sulphur dioxide cycle, which is the bottoming fluid?
a) Mercury
b) Steam
c) Sulphur dioxide
d) Cannot say
Answer: c
Explanation: Sulphur dioxide, being the only bottoming fluid in the tertiary cycle is used as a bottoming fluid.

10. The total loss in a tertiary cycle is?
a) sum of losses in the individual cycles
b) product of losses in the individual cycles
c) sum of products of individual losses
d) none of the mentioned
Answer: b
Explanation: The total loss in a tertiary cycle is product of losses in the individual cycles.

Combined Cycle Plants, Nuclear and Thermionic Power Generation

1. The maximum steam temperature in a power cycle in degree centigrade is?
a) 600
b) 500
c) 300
d) 100
Answer: a
Explanation: The maximum steam temperature in a power cycle is 600 degree centigrade.

2. The temperature in a dry bottom pulverised coal furnace, in degree Celsius is about?
a) 1200
b) 1300
c) 1400
d) 2000
Answer: b
Explanation: The temperature in a dry bottom pulverised coal furnace, in degree Celsius is about 1300.

3. What happens to the availability in a combined cycle plant?
a) decreases
b) increases
c) remains same
d) cannot say
Answer: a
Explanation: There is a great thermal irreversibility & a decrease of availability because of heat transfer from combustion gases to steam through such a large temperature difference.

4. By superposing a high temperature power plant as a topping unit to the steam plant, the energy conversion efficiency achieved is?
a) higher
b) lower
c) maximum
d) minimum
Answer: a
Explanation: By superposing a high temperature power plant as a topping unit to the steam plant, the energy conversion efficiency achieved is higher from fuel to electricity.

5. Which of the following is not a type of Combined Plant?
a) Sodium- mercury-Potassium plant
b) Gas turbine-Steam turbine plant
c) Thermionic steam plant
d) Thermoelectric steam plant
Answer: a
Explanation: Sodium-mercury-potassium plants have two topping fluids which is impossible for a plant to possess.

6. Which of these is not a component of nuclear reactor?
a) reactor core
b) refractor
c) control rod
d) biological shield
Answer: b
Explanation: A reflector rather than a refractor is a component of nuclear reactor.

7. Which of these is not a merit of nuclear power?
a) amount of fuel required is small
b) plant requires a huge amount of area
c) demand for coal and oil is reduced
d) most economical in large quantities
Answer: b
Explanation: A small amount of area is required.

8. The thermionic generator is essentially which kind of device?
a) low voltage & high current
b) high voltage & high current
c) low voltage & low current
d) high voltage and high current
Answer: a
Explanation: Thermionic generator is essentially a low-voltage & high-current device.

9. What efficiencies of thermionic power generator have been realised?
a) 50-60%
b) 40-50%
c) 10-20%
d) 30-40%
Answer: c
Explanation: Efficiency of 30-40% has been realised in thermionic generators.

10. The maximum electron current per unit area provided by an emitter is given by (where J = current density, T = absolute temperature in K, ɸ = work function in keV, k = Boltzmann’s constant & A=emission constant)
a) J = AT exp(-ɸ/kT)
b) J = AT (-ɸ/kT)
c) J = AT2 exp(-ɸ/kT)
d) J = exp(-Aɸ/kT2)
Answer: c
Explanation: The maximum current density is given by Richardson-Dushman equation.

11. In an electron beam, the average kinetic energy of an electron is given by __________
a) 2KT
b) 3KT
c) 1.5KT
d) 2.5KT
Answer: a
Explanation: The average kinetic energy is equal to 2KT.

Gas Turbine-Steam Power Plant – I

1. What is the air standard cycle for a Gas-Turbine called?
a) Reheat cycle
b) Rankine cycle
c) Brayton cycle
d) Diesel cycle
Answer: c
Explanation: Brayton cycle is an ideal air standard cycle for a Gas turbine, which, like the Rankine cycle, also comprises of two reversible adiabatic & two reversible isobars.

2. What is the difference between a Rankine cycle & a Brayton cycle?
a) working fluid in a Brayton cycle undergoes phase change while it doesn’t in Rankine cycle
b) working fluid in a Brayton cycle doesn’t undergo phase change while it does in Rankine cycle
c) both are same
d) none of the mentioned
Answer: b
Explanation: The difference between a Rankine cycle & a Brayton cycle is that the working fluid in a Brayton cycle doesn’t undergo phase change while it does in Rankine cycle.

3. Which of the following is a type of Gas Turbine Plant?
a) Single Acting
b) Double Acting
c) Open
d) None of the mentioned
Answer: c
Explanation: Open & Closed Gas Turbine plants are the two types.

4. Power is produced when the working fluid does some work on the?
a) Shaft
b) Fins
c) Blades
d) None of the mentioned
Answer: c
Explanation: For the production of power, the working fluid does some work on the blades of the turbine, thereby producing Power.

5. A Gas Turbine is which type of combustion plant?
a) external
b) open
c) internal
d) cannot say
Answer: c
Explanation: Since for the production of power, the working fluid does some work on the blades of the turbine, thereby producing Power. Hence, it is called an internal combustion plant.

6. Which among these is the main component of a gas turbine plant?
a) Condenser
b) Compressor
c) Boiler
d) Both Compressor & Boiler
Answer: b
Explanation: The main component of a Gas turbine plant is Compressor.

7. Which type of compressor is used in a gas turbine plant?
a) Reciprocating compressor
b) Screw compressor
c) Multistage axial flow compressor
d) Either Reciprocating compressor & Screw compressor
Answer: c
Explanation: Multistage axial flow compressor is the compressor in practical usage in a gas turbine plant.

8. What part or % of power developed is utilised for driving the compressor?
a) 65 %
b) 70 %
c) 55 %
d) 80 %
Answer: a
Explanation: A total of 65 % of power developed in the gas turbine is used for driving the compressor.

9. The gas turbine power plant mainly uses which among the following fuels?
a) Coal and Peat
b) Kerosene oil and diesel oil and residual oil
c) Gas oil
d) Natural gas and liquid petroleum fuel
Answer: d
Explanation: Natural gas and liquid petroleum fuel are among the two fuels used in a gas turbine.

Gas Turbine-Steam Power Plant – II

1. The heating value of gaseous fuels is about _____________
a) 500 kJ/litre
b) 30 kJ/litre
c) 100 kJ/litre
d) 10 kJ/litre
Answer: b
Explanation: 30 kJ/litre is the heating value of gaseous fuels.

2. The compressor has to be started _____________
a) Before starting the gas turbine
b) After starting the gas turbine
c) Simultaneously with starting of gas turbine
d) At any time during the operation
Answer: a
Explanation: Compressor has to be started before starting the gas turbine as the turbine work is used by compressor.

3. Which of these is not a part of a Gas Turbine Plant?
a) Compressor
b) Gas Turbine
c) Combustion chamber
d) Boiler
Answer: d
Explanation: A Gas Turbine Plant has the following parts:
Compressor, Gas Turbine, Combustion chamber.

4. What are the major field(s) of application of gas turbine?
a) Aviation
b) Oil and gas industry
c) Marine propulsion
d) All of the mentioned
Answer: d
Explanation: A Gas Turbine has applications in nearly all fields, the major ones being in the fields of Aviation, Oil & Gas industry, Marine propulsion.

5. Which of the following is (are) the limitation(s) of gas turbines?
a) They are not self-starting
b) Higher rotor speeds
c) Low efficiencies at part loads
d) All of the mentioned
Answer: d
Explanation: The limitations in the functioning of a Gas Turbines are inability of self-starting, excess rotor speeds and inability to adjust to varying loads.

6. The ratio of heat actually released by 1kg of fuel to heat that would be released by complete perfect combustion is called ___________
a) Thermal efficiency
b) Combustion efficiency
c) Engine efficiency
d) Compression efficiency
Answer: b
Explanation: Combustion efficiency is defined as,” The ratio of heat actually released by 1kg of fuel to heat that would be released by complete perfect combustion”.

7. What is the percentage of total energy input appearing as network output of the cycle?
a) Thermal efficiency
b) Combustion efficiency
c) Engine efficiency
d) Compression efficiency
Answer: a
Explanation: Thermal Efficiency is, “The percentage of total energy input appearing as network output of the cycle”.

8. Which of the following method(s) can be used to improve the thermal efficiency of open cycle gas turbine plant?
a) Inter-cooling
b) Reheating
c) Regeneration
d) All of the mentioned
Answer: d
Explanation: The various methods to improve the efficiency of open cycles include intercooling the feed water from the compressor to the turbine and then employing regeneration & reheat to just use the power of the reheated water in order to maximize the power output.

9. Which of the following is (are) used as starter for a gas turbine?
a) An Internal combustion engine
b) A steam turbine
c) An auxiliary electric motor
d) All of the mentioned
Answer: d
Explanation: There are various methods by which a Gas Turbine can be started, they are by the use of an Internal Combustion engine, a steam turbine, an auxiliary electric motor, etc.

10. Gas turbine is shut down by ____________
a) Turning off starter
b) Stopping the compressor
c) Fuel is cut off from the combustor
d) All of the mentioned
Answer: c
Explanation: The only way to stop a running Gas turbine is by cutting off the fuel supply so that the various processes in the cycle are stopped.

Gas Turbine-Steam Power Plant – III

1. In gas turbine, intercooler is placed _____________
a) before low pressure compressor
b) in between low pressure compressor and high pressure compressor
c) in between high pressure compressor and turbine
d) none of the mentioned
Answer: b
Explanation: The various methods to improve the efficiency of open cycles include intercooling the feed water from the compressor to the turbine and then employing regeneration & reheat to just use the power of the reheated water in order to maximize the power output. Here, this is done by placing the intercooler before any of the above processes.

2. In gas turbine, what is the function of Re-heater?
a) Heat inlet air
b) Heat exhaust gases
c) Heat air coming out of compressor
d) Heat gases coming out of high pressure turbine
Answer: d
Explanation: In order to make a thermodynamic process of larger efficiency, it is shifted towards isothermal behavior. For this, the output from re-generator, which is at a higher temperature is cooled to the temperature which is mid-way between the two temperature ranges. Then, it is again heated to the final temperature thereby increasing the efficiency of the cycle.

3. The ‘work ratio’ increases with _____________
a) increase in turbine inlet pressure
b) decrease in compressor inlet temperature
c) decrease in pressure ratio of the cycle
d) all of the mentioned
Answer: d
Explanation: The ‘work ratio’ increases when the turbine inlet pressure increases, the compressor inlet temperature decreases, the pressure ratio of the cycle decreases.

4. In the centrifugal compressor, total pressure varies _____________
a) directly as the speed ratio
b) square of speed ratio
c) cube of the speed ratio
d) all of the mentioned
Answer: b
Explanation: The total pressure in a centrifugal compressor is a function of speed ratio. It varies square of the speed ratio.

5. The efficiency of multistage compressor is _____ than a single stage.
a) lower
b) higher
c) equal to
d) all of the mentioned
Answer: a
Explanation: The efficiency of multistage compressor is lower than a single stage.

6. In centrifugal compressor, power input varies as _________
a) directly as the speed ratio
b) the square of speed ratio
c) the cube of the speed ratio
d) all of the mentioned
Answer: c
Explanation: Power output in a centrifugal compressor varies as the cube of the speed ratio.

7. In the ____________ heat transfer takes place between the exhaust gases and cool air.
a) Intercooler
b) Re-heater
c) Regenerator
d) Compressor
Answer: c
Explanation: The process of heat transfer between the exhaust gases and cool air takes place in Regenerator.

8. In centrifugal compressor, the diffuser converts _________
a) Kinetic energy into pressure energy
b) Pressure energy into Kinetic energy
c) Kinetic energy into Mechanical energy
d) Mechanical energy into Kinetic energy
Answer: a
Explanation: The diffuser of a centrifugal compressor converts Kinetic Energy into Pressure energy.

Mechanical Engineering MCQs – Combined Cycle Power Generation ( Power Plant Engineering ) MCQs