This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Simple Steam Power Cycle and Rankine Cycle”.
1. A power cycle continuously converts ____ into ____
a) heat, heat
b) work, heat
c) heat, work
d) work, work
View Answer
Explanation: Here heat is the energy released by burning of fuel and work is done as shaft work.
2. In the vapour power cycle, working fluid undergoes a change of phase.
a) true
b) false
View Answer
Explanation: Here working fluid is water.
3. The path followed in a vapour power cycle is
a) boiler-condenser-turbine-pump
b) boiler-turbine-condenser-pump
c) boiler-turbine-pump-condenser
d) boiler-pump-turbine-condenser
View Answer
Explanation: In the boiler, water takes heat then expands in turbine going into condenser where it condenses into water and then it is pumped back into boiler.
4. For a fluid undergoing cycle process,
a) there is no net change in its internal energy
b) energy transfer as heat is equal to the energy transfer as work
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: When a fluid undergoes a cycle process, this changes take place.
5. For a vapour power cycle,
a) net heat input is converted into net work output
b) Q1-Q2 = Wt-Wp
c) efficiency = 1 – (Q2/Q1)
d) all of the mentioned
View Answer
Explanation: Here Q1 is the heat transferred to the fluid and Q2 is the heat rejected, Wt is work transferred from fluid and Wp is work transferred into fluid.
6. In a Rankine cycle, all the processes are ideal.
a) true
b) false
View Answer
Explanation: The Rankine cycle is an ideal cycle and also a reversible cycle.
7. For a Rankine cycle, which of the following is true?
a) a reversible constant pressure heating process happens in steam boiler
b) reversible adiabatic expansion of steam in turbine
c) reversible constant pressure heat rejection in condenser
d) all of the mentioned
View Answer
Explanation: All the processes are ideal in Rankine cycle.
8. The liquid water handled by pump is
a) incompressible
b) with increase in pressure, there is a little change in density or specific volume
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: In a pump, reversible adiabatic compression of liquid takes place.
9. The work ratio is defined as the ratio of
a) positive work output to net work output
b) net work output to positive work output
c) heat input to work output
d) none of the mentioned
View Answer
Explanation: The work ratio = Wnet / Wt.
10. Steam rate is the rate of steam flow required to produce unit shaft output.
a) true
b) false
View Answer
Explanation: It is the capacity of a steam plant and steam rate = 1/(Wt-Wp).
11. Heat rate is given by (in kJ/kWh)
a) cycle efficiency
b) 3600 / cycle efficiency
c) cycle efficiency / 3600
d) cycle efficiency * 3600
View Answer
Explanation: Heat rate is the rate input required to produce unit work output.
12. Which of the following statement is true?
a) during compression, specific volume of the fluid should be kept small
b) during expansion, specific volume of the fluid should be kept large
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: The larger the specific volume, more is the work produced or consumed by the steady-flow device.
13. Work output of turbine is ____ the work input to the pump.
a) much larger
b) much smaller
c) equal to
d) none of the mentioned
View Answer
Explanation: This is the reason why steam power plants is so popular.
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