Thermodynamics Multiple Choice Questions on “Ideal Regenerative Cycle and Regenerative Cycle”.
1. The mean temperature of heat addition can be increased by
a) increasing the amount of heat supplied at high temperatures
b) decreasing the amount of heat added at low temperatures
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: These are the two ways of increasing mean temperature of heat addition.
2. In the ideal regenerative cycle, the condensate after leaving the pump circulates around the turbine casing.
a) true
b) false
Answer: a
Clarification: Through this heat transfer takes place between the vapour flowing through the turbine and liquid flowing around the turbine.
3. The efficiency of an ideal regenerative cycle is given by
a) 1 – (T1/T2)
b) 1 – (T2/T1)
c) 1 – (Q1/Q2)
d) none of the mentioned
Answer: b
Clarification: The efficiency of a cycle is given by 1 – (Q2/Q1).
4. The efficiency of an ideal regenerative cycle is ____ the Carnot cycle efficiency.
a) greater than
b) equal to
c) less than
d) none of the mentioned
Answer: b
Clarification: For both the cycles, efficiency is given by 1 – (T2/T1).
5. When compared with the Rankine cycle, the ideal regenerative cycle has
a) less net work output
b) more steam rate
c) more efficient
d) all of the mentioned
Answer: d
Clarification: These indiate that the ideal regenerative cycle is better than the Rankine cycle but it is not practicable.
6. The ideal regenerative cycle is not practicable because
a) reversible heat transfer can’t be obtained in finite time
b) heat exchanger in turbine is mechanically impracticable
c) there is high moisture content of steam in the turbine
d) all of the mentioned
Answer: d
Clarification: These reasons result in the ideal regenerative cycle being not used practically.
7. For a regenerative cycle, which of the following is true?
a) efficiency = (Q1-Q2)/Q1
b) efficiency = (Wt-Wp)/Q1
c) steam rate = 3600/(Wt-Wp)
d) all of the mentioned
Answer: d
Clarification: These are the expressions for steam rate and cycle efficiency for a regenerative cycle.
8. The efficiency of regenerative cycle will be ____ the efficiency of the Rankine cycle.
a) greater than
b) equal to
c) less than
d) none of the mentioned
Answer: a
Clarification: The reason being, with regeneration, the mean temperature of heat addition increases.
9. Which of the following is an assumption for heaters?
a) they are adequately insulated
b) there is no heat gain from or heat loss to the surroundings
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: This assumption is necessary for the heaters.
10. The heating of feedwater by steam bled from the turbine, carnotizes the Rankine cycle.
a) true
b) false
Answer: a
Clarification: This comes from the equation obtained for the regenerative cycle.