# Vapour Power Cycles - Mechanical Engineering (MCQ) questions and answers

1)   The below diagram is the T-s diagram of the Rankine cycle with reheat.
Which process represents the reheat?

a. process 1 – 2
b. process 2 – 2 ′
c. process 2 ′ – 2 ″
d. process 2 – 3 ′
 Answer  Explanation ANSWER: process 2 ′ – 2 ″ Explanation: No explanation is available for this question!

2)   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  Explanation ANSWER: freezing point of working fluid should be below the room temperature Explanation: No explanation is available for this question!

3)   What is the relation between brake efficiency, internal efficiency and mechanical efficiency?

a. ηInternal = ηMech * ηBrake
b. ηMech = ηInternal * ηBrake
c. ηBrake = ηInternal * ηMech
d. none of the above
 Answer  Explanation ANSWER: ηBrake = ηInternal * ηMech Explanation: No explanation is available for this question!

4)   What is the correct formula for brake efficiency of the turbine in vapour power cycle?
Where out flow is as following,Ideal output(Actual work given to turbine) ----> Internal losses ----> Internal output (Actual work produced by turbine turbine) ----> External losses -----> Brake output (Actual work at the shaft)

a. ηBrake = Brake output / Ideal output
b. ηBrake = Brake output / Internal output
c. ηBrake = Ideal output / Brake output
d. ηBrake = Internal output / Brake output
 Answer  Explanation ANSWER: ηBrake = Brake output / Ideal output Explanation: No explanation is available for this question!

5)   In binary vapour cycle, the cycle which is operated in high pressure ratio is called as

a. bottoming cycle
b. topping cycle
c. upper cycle
d. pressure cycle
 Answer  Explanation ANSWER: topping cycle Explanation: No explanation is available for this question!

6)   When two vapor 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 above
 Answer  Explanation ANSWER: Binary vapour cycle Explanation: No explanation is available for this question!

7)   The specific heat of the ideal working fluid used in vapor power cycle

a. should be constant
b. should be large
c. should be small
d. none of the above
 Answer  Explanation ANSWER: should be small Explanation: No explanation is available for this question!

8)   What should be the critical temperature of working fluid for maximum efficiency of vapour power cycle?

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 above
 Answer  Explanation ANSWER: the working fluid should have critical temperature as high as possible Explanation: No explanation is available for this question!

9)   As the heat rejection temperature decreases in the vapour power cycle below atmospheric pressure,

a. the vacuum in the condenser also decreases
b. the vacuum in the condenser increases
c. it does not produce any vacuum in condenser
d. none of the above
 Answer  Explanation ANSWER: the vacuum in the condenser increases Explanation: No explanation is available for this question!

10)   What 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 above
 Answer  Explanation ANSWER: all of the above Explanation: No explanation is available for this question!

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