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

1)   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!


2)   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!


3)   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!


4)   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!


5)   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!


6)   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!


7)   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!


8)   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!


9)   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!


10)   A closed feedwater heater system

a. has high heat transfer capacity
b. requires pump at each heater to handle the large feedwater stream
c. requires only single pump regardless of the number of heaters
d. does not require any pump as the extracted steam and feedwater are not allowed to mix
Answer  Explanation 

ANSWER: requires only single pump regardless of the number of heaters

Explanation:
No explanation is available for this question!


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