Deck 8: Steam Power Plant and Rankine Cycle

Question 1

The latent heat of vapouristation at critical point is

A)less than zero
B)greater than zero
C)equal to zero
D)none of the above

Answer 1

equal to zero

Question 2

Choose the correct answer

A)critical point involves equilibrium of solid & vapour phases
B)critical point involves equilibrium of solid & liquid phases
C)critical point involves equilibrium of solid, liquid & vapour phases
D)triple point involves equilibrium of solid, liquid & vapour phases

Answer 2

triple point involves equilibrium of solid, liquid & vapour phases

Question 3

With the increase in pressure

A)boiling point of water increases & enthalpy of evaporation increases
B)boiling point of water increases & enthalpy of evaporation decreases
C)boiling point of water decreases & enthalpy of evaporation increases

Answer 3

boiling point of water increases & enthalpy of evaporation decreases

Question 4

With increase in pressure

A)enthalpy of dry saturated steam increases
B)enthalpy of dry saturated steam decreases
C)enthalpy of dry saturated steam remains same
D)enthalpy of dry saturated steam first increases & thendecreases

Question 5

Dryness fraction of steam is defined as

A)mass of water vapour in suspension/(mass of water vapour in suspension+mass of dry steam)
B)mass of dry steam/mass of water vapour in suspension
C)mass of dry steam/(mass of dry steam+mass of water vapour in suspension)
D)mass of water vapour in suspension/mass of dry steam

Question 6

Only throttling calorimeter is used for measuring

A)very low dryness fraction upto 0.7
B)very high dryness fraction upto 0.98
C)dryness fraction of only low pressure steam
D)dryness fraction ofonly high pressure steam

Question 7

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%

Question 8

Rankine cycle operating on low pressure limit of p1 & high pressure limit 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 pressurelimits
C)has same thermal efficiency than carnot cycle operating between same pressure limits
D)may be more or less depending upon the magnitudes of p1 & p2

Question 9

Rankine cycle comprises of

A)two isetropic processes & two constant volume processes
B)two isentropic processes & two constant pressureprocesses
C)two isothermal processes & two constant pressureprocesses
D)none of the above

Question 10

In Rankine cycle the work output from the turbine is given by

A)change of internal energy between inlet & outlet
B)change of enthalpy between inlet & outlet
C)change of entropy between inlet & outlet
D)change of temperature between inlet & outlet

Question 11

The maximum percentage gain in Regenerative feed heating cycle thermal effciency

A)increases with number of feed heaters increasing
B)decreases with number of feed heaters increasing
C)remains same unaffected by number of feed heaters
D)none of the above

Question 12

In an unsaturated air the state of a vapour is

A)wet
B)superheated
C)saturated
D)unsaturated

Question 13

The efficiency of the Carnot cycle may be increased by

A)decreasing the lowest temperature
B)increasing the lowest temperature
C)increasing the highest temperature
D)both a & c

Question 14

Most of the fossil fuel based power plants operate on

A)rankine cycle
B)brayton cycle
C)carnot cycle
D)either rankine or brayton cycle

Question 15

Efficiency of Rankine cycle is function of

A)highest temperature of cycle
B)lowest temperature of cycle
C)both highest & lowest temperature of the cycle
D)none of the above

Question 16

Essential parts of a power plant operating on a Rankine cycle are

A)engine or turbine
B)engine or turbine & conderser
C)gine or turbine, condenser, pump &boiler
D)engine or turbine & boiler

Question 17

Correlate the following statements
i. the volume of water into which steam is condensed in condenser is very much smaller than the volume of steam before condensation
ii. the net work of a Rankine cycle is heat supplied in boiler - heat rejected to condenser - pump work

A)both i & ii are correct, i is the correct reason for ii
B)i & ii are correct, ii is the correct interpretation if i
C)both i & ii are not correct
D)both i & ii are independently correct

Question 18

By reducing the condenser pressure in Rankine power plant

A)heat supplied increases & work of cycle decreases
B)work of cycle & moisture content of steam in l.p side ofturbine increase
C)heat supplied & efficiency of cycle increase
D)work of cycle increases but heat supplied decreases

Question 19

Correlate the following statements
i. by reducing the condenser pressure in a Rankine cycle work output is increased
ii. increased proportion of moisture in turbine is undesirable because water particles erode the blades

A)both i & ii are independently true
B)both i & ii are not true
C)i is true but ii is not
D)ii is true but i is not

Question 20

Turbine blade efficiency reduces in a Rankine cycle if

A)heat supply in boiler increases
B)heat supply in boiler decreases
C)condenser pressure decreases
D)condenser pressure increases

Question 21

A Rankine cycle with reheat

A)increases heat supply but reduces work
B)increases efficiency but reduces work
C)increases moisture content in l.p side of turbine but increases work
D)increases efficiency but reduces moisture content in l.p side of turbine

Question 22

The main advantage of a Reheat Rankine cycle is

A)reduced moisture content in l.p side of turbine
B)increased efficiency
C)increased work of turbine
D)reduced load on condenser

Question 23

A Reheat Rankine cycle

A)reduces total heat produced in boiler
B)increases total heat produced in boiler
C)increases volume of steam produced in boiler
D)reduces volume of steam produced inboiler

Question 24

Choose the wrong statement

A)volume of steam passing through h.p & l.p sides of the turbine is same in simple rankine cycle
B)volume of steam passing through l.p side of turbine & condenser is same in regenerative rankine cycle
C)volume of steam passing through h.p side of the turbine & condenser is same in regenerative rankinecycle
D)volume of steam passing through h.p side of the turbine & condenser is same in reheat rankine cycle

Question 25

Examine follwing two statements & choosethe correct relationship
i. for a steam power plant Rankine cycle is preferred over Carnot cycle
ii. a pump which will handle the mixture of vapour & liquid is difficult to construct

A)both i, ii are correct & i is the consequence of ii
B)both i & ii are independently correct
C)i) is correct but ii is not
D)ii) is correct but i is not