MCQ Question on Steam Power Plant

1.     Which of these is a ‘fissile fuel’?
a) Thorium
b) Carbon
c) Potassium
d) Graphite

Answer: a
Explanation: A fissile fuel is one that is based on a sustained chain reaction with neutrons of any energy.

2.     Which of these is a ‘working fluid’ in liquid phase?
a) Water
b) Steam
c) Mercury
d) Oxygen

Answer: a
Explanation: The working fluid is water in liquid phase & steam in gas phase.

3.     Which of these is an output of a ‘Furnace’?
a) Fuel gas
b) Air
c) Flue gases
d) Water Vapor

Answer: c
Explanation: A furnace takes in a Fuel gas, Air & Water Vapour while it gives off Flue Gases.

4.     What kind of energy output is obtained from a ‘Steam Power Plant’?
a) Heat energy
b) Sound energy
c) Electricity
d) Thermal energy

Answer: c
Explanation: A ‘Steam Power Plant’ is used primarily for electricity generation.

5.     What kind of a process does a ‘Steam Power Plant’ undergoes?
a) Adiabatic
b) Cyclic
c) Irreversible
d) Expansion

Answer: b
Explanation: As the internal energy change in the ‘Steam Power Plant’ is ZERO. Hence, the entire plant obeys a Cyclic Process. 

6.     Water that is fed back to the boiler by the pump is called?
a) Adsorbate
b) Absorbate
c) Condenset
d) Condensate

Answer: d
Explanation: The water feedback is from condenser & its called condensate.

7.     The net change in internal energy in a steam power plant is?
a) Positive
b) Negative
c) Zero
d) None of the mentioned

Answer: c
Explanation: As the steam power plant is based on a cyclic process. A cyclic process has a net change in internal energy=0.

8.     The product of efficiency & heat transferred to the working fluid is?
a) Net temperature change
b) Net work done
c) Net enthalpy change
d) None of the mentioned

Answer: b
Explanation: The formula of efficiency of a steam power plant is,
Efficiency = net work done/net heat transferred

9.     What are the components of a Steam Power Plant?
a) Evaporator, Condenser, Boiler, Expansion valve
b) Evaporator, Condenser, Boiler, Turbine
c) Boiler, Turbine, Condenser, Pump
d) Boiler, Turbine, Pump, Expansion valve

Answer: c
Explanation: A Steam Power Plant has the sequence,
Boiler, Turbine, Condenser, Pump.

10.  Shaft work is fed to __________ for getting an electrical output.
a) Motor
b) Generator
c) Rotor
d) Accelerator

Answer: b
Explanation: The flow in a Steam Power Plant follows the sequence,
Source-Shaft-Generator.

11.     Ideal ‘Rankine Cycle’ is a __________ process.
a) Reversible
b) Irreversible
c) Reversible & Irreversible
d) None of the mentioned

Answer: a
Explanation: Ideal Rankine Cycle is a reversible process.

12.    For analytical purposes, the Rankine Cycle is assumed to be in _____________
a) Unsteady flow operation
b) Turbulent flow operation
c) Steady flow operation
d) Laminar flow operation

Answer: c
Explanation: For analytical purposes, always steady flow operation is considered, as in unsteady flow, the various fluid properties vary considerably which remain same when the steady flow operation is assumed.

13. The net work done in a Rankine Cycle is the difference of _____________
a) Condenser work & Boiler work
b) Boiler work & Pump work
c) Turbine Work & Pump work
d) Condenser work & Pump work

Answer: c
Explanation: The net work done in a Rankine Cycle is given by,

W_net = W_t – W_p.

14 In a Rankine Cycle, heat input is provided to ___________
a) Condenser
b) Pump
c) Turbine
d) Boiler

Answer: d
Explanation: As the heating of the liquid working fluid occurs in the Boiler, the heat input is provided to the Boiler for the same.

15.    In a Rankine Cycle, heat output is obtained from ___________
a) Condenser
b) Boiler
c) Turbine
d) Pump

Answer: a
Explanation: As the heated water comes to the condenser, it loses its heat & gets condensed. The heat output is obtained from Condenser.

16.  The water that flows from the Pump is?
a) Compressible
b) Incompressible
c) Unsteady
d) None of the mentioned

Answer: b
Explanation: The water flowing through the pump is incompressible so as to extract work from the turbine.

17. Steam Rate is the reciprocal of _________
a) Net work done
b) Heat extracted from condenser
c) Heat given to reciprocal
d) Work done by turbine

Answer: a
Explanation: Steam Rate is given by,
Steam Rate = 1/W_net.

18.  Which of these is sometimes neglected?
a) Turbine work
b) Pump work
c) Condenser heat
d) Boiler heat

Answer: b
Explanation: Pump Work is very small as compared to Turbine Work & so is often neglected.

19.     Efficiency of a Rankine Cycle is also expressed as __________
a) Capacity Ratio
b) Heat Rate
c) Heat Ratio
d) Steam Rate

Answer: b
Explanation: The relation between Heat Rate & Efficiency is,
Heat Rate = Efficiency of a Rankine Cycle.

20.  Steam Power Plants are more popular in electric power generation because ___________
a) Work output of turbine is very large than work input to the pump
b) Work output of turbine is very small than work input to the pump
c) Work output of turbine is equal to work input to the pump
d) None of the mentioned

Answer: a
Explanation: In a Steam Power Plant, the positive difference of turbine work & pump work makes it useful in electricity generation.

21. Which is the most common type of Evaporator?
a) Flooded Evaporator
b) Plate Evaporator
c) Coil Evaporator
d) Brine Evaporator

Answer: b
Explanation: The most common type is a coil winding on a plate & so the name ‘plate evaporator’.

22.    In Rankine Cycle, water is converted to saturated liquid in ___________
a) Evaporator
b) Economizer
c) Superheater
d) Preheater

Answer: b
Explanation: The saturation of water occurs in an Economizer in a Rankine Cycle.

23.    If Evaporator & Condenser pressures are p & q, the intercooler pressure P is given as?
a) P = pq
b) P = p/q
c) P = (pq)^(1/2)
d) P = p²q

Answer: c
Explanation: The relation between Intercooler pressure, Evaporator & Condenser is,
P = (pq)^(1/2).

24.  Phase change at constant pressure takes place in _____________
a) Economiser
b) Evaporator
c) Superheater
d) Air-Preheater

Answer: c
Explanation: Superheater undergoes a change in phase at constant pressure.

25.  Which of these factors don’t cause Internal Irreversibility of a Rankine cycle?
a) Throttling
b) Mixing
c) Fluid Friction
d) Fluid flow

Answer: d
Explanation: The Rankine cycle is an Irreversible cycle. For a cycle to be irreversible naturally throttling, mixing & friction in fluids are the factors that cause this Irreversibility.

26.What is the unit of Heat rate?
a) kJ/KW
b) KW/kJ
c) kJ
d) KW

Answer: a
Explanation: Heat rate is the rate of input required to produce unit shaft output.

27.  Rankine cycle operating on low pressure limit of p1 and high pressure limit of p2 ___________
a) has higher thermal efficiency than the Carnot cycle operating between same pressure limits
b) has lower thermal efficiency than Carnot cycle operating between same pressure limits
c) has same thermal efficiency as Carnot cycle operating between same pressure limits
d) may be more or less depending upon the magnitudes of p1 and p2

Answer: a
Explanation: Area under P-V curve for Rankine will be more as compared to Carnot cycle.

28.  Rankine efficiency of a Steam Power Plant ___________
a) improves in Summer as compared to that in Winter
b) improves in Winter as compared to that in Summer
c) is unaffected by climatic conditions
d) none of the mentioned

Answer: b
Explanation: In winters, the temperature of cooling water is low, which increases Condenser’s efficiency.

29.   Rankine cycle comprises of ___________
a) two isentropic processes and two constant volume processes
b) two isentropic processes and two constant pressure processes
c) two isothermal processes and two constant pressure processes
d) none of the mentioned

Answer: b
Explanation: Rankine cycle is a reversible cycle which have two constant pressure and two constant temperature processes.

30.     In Rankine cycle, the work output from the turbine is given by ___________
a) change of internal energy between inlet and outlet
b) change of enthalpy between inlet and outlet
c) change of entropy between inlet and outlet
d) change of temperature between inlet and outlet

Answer: b
Explanation: Work output(turbine) = h1 – h2.

31.     Which of the following contributes to the improvement of efficiency of Rankine cycle in a Thermal Power Plant?
a) reheating of steam at intermediate stage
b) regeneration use of steam for heating Boiler feed water
c) use of high pressures
d) all of the mentioned

Answer: d
Explanation: The regenerative features effectively raise the nominal cycle heat input temperature, by reducing the addition of heat from the Boiler/fuel source at the relatively low feedwater temperatures that would exist without regenerative feedwater heating.

32.  Match the following:

i) Boiler                 A. reversible adiabatic expansion of steam

ii) turbine               B. constant pressure heat heat addition

iii) Condenser        C. reversible adiabatic compression

iv) pump                D. constant pressure heat rejection

a)     i-B ii-A iii-D iv-C
b) i-A ii-C iii-D iv-A
c) i-B ii-D iii-C iv-A
d) i-A ii-D iii-B iv-C

Answer: a
Explanation: Working fluid in Rankine cycle undergoes 4 processes, expansion in turbine, heat addition in Boiler, heat rejection in Condenser and compression in pump.

33.   What is the actual turbine inlet temperature in Rankine cycle?
a) 700C
b) 800C
c) 550C
d) 1150C

Answer: c
Explanation: The TIT(Turbine Inlet Temperature) is of the range 500-570C.

34.    Rankine cycle efficiency of a good Steam Power Plant may be in the range of?
a) 15 to 20%
b) 35 to 45%
c) 70 to 80%
d) 90 to 95%

Answer: b
Explanation: Efficiency of Rankine cycle in actual working condition is found to be between 35 to 45%.

35. A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350°C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle?
a) 7.7
b) 17.7
c) 27.7
d) 37.7

Answer: c
Explanation: Fixing the states; h1 = 340.5 kJ/kg, h2 = h1 + v1 (P2 – P1) = 343.5 kJ/kg, h3 = 3115.3 kJ/kg, s3 = 6.7428 kJ/kg – K, x4 = 0.869, and h4 = 2343.9 kJ/kg. Thus, η = 1 – Qout / Qin = 1 – (h4 – h1) / (h3 – h2) = 27.7%.

36.   A simple Rankine cycle produces 40 MW of power, 50 MW of process heat and rejects 60 MW of heat to the surroundings. What is the utilization factor of this co generation cycle neglecting the pump work?
a) 50
b) 60
c) 70
d) 80

Answer: b
Explanation: Application of the first law to the entire cycle gives Qin = Qp + Qreject + W = 150 MW. The utilization factor is then = (Qp + W) / Qin = 60%.

37.    A gas turbine works on __________
a) Carnot cycle
b) Brayton cycle
c) Dual cycle
d) Rankine cycle

Answer: b
Explanation: A gas turbine works on 2 isentropic and 2 isobaric processes which is nothing else but Brayton cycle.

38.     What is the range of Thermal efficiency in the Brayton cycle?
a) 30-35%
b) 40-45%
c) 50-55%
d) 50-60%

Answer: c
Explanation: Efficiency of Brayton cycle in actual working condition is found to be between 35 to 45%.

39.  What is the maximum possible TIT(Turbine Inlet Temperature)?
a) 1000 K
b) 1500 K
c) 950 K
d) 1300 K

Answer: d
Explanation: The maximum temperature is limited by metallurgical conditions.

40.  A simple Brayton cycle uses Helium as the working fluid, has a maximum temperature of 1000 K, and a pressure ratio of 4. At the start of the compression, the Helium pressure and temperature are 50 kPa and 250 K. Based upon cold-air standard analysis assumptions, the thermal efficiency of the cycle is?
a) 0.13
b) 0.23
c) 0.43
d) 0.53

Answer: d
Explanation: Using the pressure ratio = 1 – rp(1 – k) / k.

41.  A simple Brayton cycle has a pressure ratio of 5 and a maximum temperature of 900 K. Air enters the compressor at 100 kPa, 300 K. Based upon cold-air standard analysis assumptions, the back-work ratio of this cycle is?
a) 0.23
b) 0.53
c) 0.48
d) 0.36

Answer: b
Explanation: Using the pressure ratio and isentropic process relations, T2 = T1rp(k – 1) / k = 475 K and T4 = T3rp(1 – k) / k = 568 K. Application of the first law to the compressor and turbine processes and substituting the results into the back-work ratio definition produces rb = (T2 -T1) / (T3 -T4) = 0.53.

42.  Which of the following methods can be used to increase efficiency of a Brayton cycle?
a) Regeneration
b) Increasing pressure ratio
c) Heat exchanger
d) All of the mentioned

Answer: d
Explanation: A heat exchanger that acts as a counter-flow energy recovery device positioned within the supply and exhaust air streams of an air handling system, in order to recover the waste heat.

43.    For the same maximum pressure and heat input, the most efficient cycle is?
a) Brayton cycle
b) Carnot cycle
c) Rankine cycle
d) Dual cycle

Answer: a
Explanation: Efficiency of a Brayton cycle is directly proportional to pressure ratio.

44.   The compression ratio is the ratio of ____________
a) Swept volume to total volume
b) Total volume to swept volume
c) Total volume to clearance volume
d) None of the mentioned

Answer: a
Explanation: According to definition, compression ratio is the ratio of swept volume to total volume.

45.   A Sterling engine uses an energy source whose temperature is 727°C and an energy sink whose temperature is 27°C. How much heat must be added to the engine to produce 1 unit of work?
a) 1.10
b) 1.19
c) 1.43
d) 2.0

Answer: c
Explanation: Since the Sterling engine is totally reversible, its thermal efficiency is the same as that of a Carnot engine, η = 1 – Tl / Th = 0.7. Now, the definition of the thermal efficiency gives Qin / Wout = 1 / η = 1.43.

46.  Which of the following is not a component of Brayton cycle?
a) Compressor
b) Combustion Chamber
c) Turbine
d) Pump

Answer: d
Explanation: Pump is used in Rankine cycle to circulate water from Condenser to Boiler.

47.    For a given value of mean temperature of heat addition(Tm) is?
a) efficiency of Rankine is more if turbine exit temperature(Tmin) is less
b) efficiency of Rankine is less if turbine exit temperature(Tmin) is less
c) efficiency does not depend on turbine exit temperature
d) none of the mentioned

Answer: a
Explanation: Efficiency = 1 – Tmin / Tm.

48. Mean temperature of heat addition can be increased by?
a) decreasing the amount of heat added
b) increase the amount of heat added
c) increase condensor pressure
d) decreasing Turbine Inlet Temperature(TIT)

Answer: c
Explanation: Increasing condensor pressure decreases turbine exit temperature which in turn increases mean temperature of heat addition.

49.   Internal irreversibility of Rankine cycle is caused by?
a) fluid friction
b) throttling and mixing
c) expansion and compression process are quite rapid
d) all of the mentioned

Answer: d
Explanation: Practical analysis shows that Internal irreversibility of Rankine cycle depends upon above stated factors.

50.    Which of the following statement is true?
a) efficiency is directly proportional to mean temperature of heat addition
b) efficiency is inversely proportional to mean temperature of heat addition
c) efficiency is exponential function of mean temperature of heat addition
d) efficiency does not depend on mean temperature of heat addition

Answer: a
Explanation: Efficiency = 1 – Tmin / Tm.

51.  Pulverized coal is ____________
a) coal free from ash
b) non-smoking coal
c) coal which bums For long time
d) coal broken into fine particles

Answer: d
Explanation: Pulverized coal also known as powdered coal or coal dust since it is as fine as face powder in cosmetic make-up.

52.   What is caking in Power Plants?
a) making cakes of coal out of fine powders
b) a variety of free burning coals
c) coal produced from burning of wood in inert atmosphere
d) in boiler furnace some coals become plastic and form lumps or masses of coal

Answer: d
Explanation: When many bituminous coals are heated, they soften and form a plastic mass that swells and re solidifies into a porous solid.

53.   Water gas is a mixture of ___________
a) CO₂ and O₂
b) O₂ and H₂
c) H₂, N₂ and O₂
d) CO, N₂ and H₂

Answer: b
Explanation: Water gas is basically HHO that is H₂ and O₂.

54.     Critical pressure of water is ___________
a) 1 kg / cm²
b) 100 kg / cm²
c) 155 kg / cm²
d) 217.7 kg / cm²

Answer: d
Explanation: The critical pressure of a substance is the pressure required to liquefy a gas at its critical temperature.

55.Coal used in power plant is also known as ___________
a) steam coal
b) charcoal
c) coke
d) soft coal

Answer: a
Explanation: Because this coal is used to generate steam.

56.   The temperature to which air must be cooled in order to become saturated is the ___________
a) minimum temperature
b) dew point temperature
c) wet-bulb temperature
d) freezing point

Answer: b
Explanation: The dew point is the temperature at which the water vapour in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates.

57.  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

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

58.    If T₂ is the temperature of heat rejection, T_ml 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/T_ml)
b) n = 1+(T₂/T_ml)
c) n = (T₂/T_ml)
d) n = 1/(T₂/T_ml)

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

59. 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

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

60.   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

Answer: b
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.

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

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

62.     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

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

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

Answer: c
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.

64.   Pelton Wheel Turbine is suited for ____________
a) high heads
b) low heads
c) medium heads
d) zero heads

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

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

Answer: b
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.

66.     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

Answer: b
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.

67.      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

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

68.  Work input and work outputs are given & obtained in ____________
a) 2 reversible adiabatics
b) 2 reversible isotherms
c) 1 reversible isotherm & 1 reversible adiabatic
d) 2 reversible isotherms & 1 reversible adiabatic

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

69.    Heat input & output is obtained in ____________
a) 2 reversible adiabatics
b) 2 reversible isotherms
c) 1 reversible isotherm & 1 reversible adiabatic
d) 2 reversible isotherms & 1 reversible adiabatic

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

70.   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

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

71.   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

Answer: a
Explanation: Heat Transfer & Friction are the factors affecting the conditions of a Carnot Cycle.