# Power Plant Questions and Answers – Mean Temperature of Heat Addition – 2

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This set of Power Plant Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Mean Temperature of Heat Addition – 2”.

1. Mean Temperature of Heat Addition is the ratio of?
a) Difference of temperatures to difference of entropies
b) Difference of enthalpies to difference of entropies
c) Difference of temperatures to difference of enthalpies
d) Difference of entropies to difference of enthalpies.

Explanation: The formula for Mean Temperature of Heat Addition is given by,
Tml = (h1 – h4)/(s1 – s4).

2. If T2 is the temperature of heat rejection, Tml is the mean temperature of heat addition, the efficiency n of a Rankine Cycle is given by which of the expressions?
a) n = 1-(T2/Tml)
b) n = 1+(T2/Tml)
c) n = (T2/Tml)
d) n = 1/(T2/Tml)

Explanation: The expression for the efficiency of a Rankine Cycle is given as,
n = 1-(T2/Tml).

3. The saturation pressure corresponding to the minimum practicable temperature of heat rejection is a function of?
a) Temperature of heat rejection
b) Temperature of surroundings
c) Mean temperature of heat addition
d) None of the mentioned

Explanation: The relation between saturation pressure & mean temperature of heat addition is given by,
EfficiencyRankine = f(Tml)
where, Tml = Mean temperature of heat addition.

4. What is the effect of the increase in the superheat at constant pressure?
a) Decreases cycle efficiency
b) Increases mean temperature of heat addition
c) Decreases mean temperature of heat addition
d) None of the mentioned

Explanation: As there is an increase in superheat at constant pressure, the cycle efficiency increases & hence there is an increase in the mean temperature of heat addition.

5. PWR stands for?
a) Pressurized Water Relator
b) Pressurized Water Reheater
c) Pressurized Water Reactor
d) Pressurized Water Refractory

Explanation: PWR stands for Pressurized Water Reactor which does not use Superheat.

6. The maximum temperature of steam that can be used is fixed from metallurgical considerations. This temperature limit is called?
a) Mining Limit
b) Metallurgical Limit
c) Metallic Limit
d) None of the mentioned

Explanation: ‘Metallurgical Limit’ is defined as the lowest temperature limit of usable steam fixed by metallurgical considerations.

7. Most of the turbine expansion takes place in?
a) Liquid Region
b) Solid Region
c) Vapour Region
d) Plastic Region

Explanation: Most of the turbine expansion should take place in the vapour region, so as to increase the life of the blades of the turbine.

8. Pelton Wheel Turbine is suited for?

Explanation: A Pelton wheel turbine is based on the principle of changing Kinetic Energy of fluid into output work.

9. A Hydraulic Ram Pump is based on the principle of?
a) Wind Hammer
b) Water hammer
c) Wind gushing
d) None of the mentioned

Explanation: A Hydraulic Ram Pump is based on the principle of Water Hammer. This principle states that, “When a flowing fluid is stopped suddenly, the kinetic energy of the rapidly moving fluid decreases to zero & in turn, increases the pressure which pulls the fluid to high heads.

10. Which of the following diagrams are used while analyzing the effect of superheat & Inlet Pressure on mean temperature of heat addition?
a) P-V diagram
b) T-S diagram
c) P-T diagram
d) V-T diagram

Explanation: Using the T-S diagram gives us an overview as to where a particular process occurs, i.e., it is within the solid region, the gaseous region or the vapour region. So, here, we prefer T-S diagram for analysis process.

11. Which of these constitute a Carnot Cycle?
a) 2 reversible isotherms & 2 reversible adiabatics
b) 1 reversible isotherms & 2 reversible adiabatics
c) 2 reversible isotherms & 1 reversible adiabatics
d) 1 reversible isotherms & 2 reversible adiabatics

Explanation: A combination of 2 reversible isotherms & 2 reversible adiabatics gives a Carnot Cycle (from the P-V diagram).

12. Work input and work outputs are given & obtained in?
b) 2 reversible isotherms
c) 1 reversible isotherm & 1 reversible adiabatic
d) 2 reversible isotherms & 1 reversible adiabatic

Explanation: The work input & output are both in the 2 reversible adiabatics (from the P-V diagram).

13. Heat input & output is obtained in?
b) 2 reversible isotherms
c) 1 reversible isotherm & 1 reversible adiabatic
d) 2 reversible isotherms & 1 reversible adiabatic

Explanation: The heat inputs & outputs are in 2 reversible isotherms (from the P-V diagram).

14. The elements of a Carnot heat engine are?
a) Heat Exchangers, Turbine, Pump
b) Heat Exchangers, Turbine, Evaporator
c) Heat Exchangers, Turbine, Condenser
d) Heat Exchangers, Turbine, Superheater

Explanation: There are 2 heat exchangers, a turbine & a pump in a Carnot heat engine.

15. Which of these shouldn’t be there in the pipelines of working fluid for achieving the conditions of Carnot Cycle?
a) Heat Transfer
b) Insulation
c) Lubrication
d) Zero Friction 