# Thermal Engineering 32

Objective Questions and Answer: Thermal Engineering 32

Subject: Thermal Engineering 32

Part 32: Objective questions and answers of Thermal Engineering

Q1. In a throttling process

a) Heat transfer takes place

b) Work is done by the expanding steam

c) Internal energy of steam changes

d) None of the above.

Q2. The pressure at which latent heat of vaporization of water is zero, is

a) Below atmospheric pressure

b) 1 kg/cm^2

c) 225.6 kg/cm^2

d) 170 kg/cm^2

Q3. Latent heat of dry steam at atmospheric pressure is equal to

a) 539 kcal/kg

b) 539 BTU/lb

c) 427 kcal/kg

d) 100 kcal/kg

Q4. The latent heat of steam with increase of pressure

a) Remains same

b) Increases

c) Decreases

d) Behaves unpredictably

Q5. At critical point, i.e. P=225.65 kg/cm^2, the latent enthalpy of vaporization is

a) Maximum

b) Minimum

c) Zero

d) Depends on temperature also

Q6. At which pressure the properties of water and steam become identical

a) 0.1 kg/cm^2

b) 1 kg/cm^2

c) 100 kg/cm^2

d) 225.6 kg/cm^2

Q7. In an experiment to determine dryness fraction of steam, the mass of water separated

was 1.2 kg in 15 mts and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is

a) 40%

b) 25%

c) 50%

d) 80%

Q8. While steam expands in turbines, theoretically the entropy

a) Remains constant

b) Increases

c) Decreases

d) Behaves unpredictably

Q9. Heating wet steam at constant temperature is heating it at constant

a) Volume

b) Pressure

c) Entropy

d) Enthalpy

a) Essentially an isentropic process

b) Non-heat transfer process

c) Reversible process

d) Constant temperature process

Q11. The state of vapour under saturation condition is described by

a) Pressure alone

b) Temperature alone

c) Pressure and temperature

d) Pressure and dryness fraction

Q12. Pick up the wrong statement about critical condition of steam

a) Latent heat is zero

b) Liquid directly becomes steam

c) Specific volume of steam and liquid is same

d) This is the maximum pressure limit

Q13. Water boils when its vapour pressure

a) Equals that of the surroundings

b) Equals 760 mm of mercury

c) Equals to atmospheric pressure

d) Equals the pressure of water in the container

Q14. Mechanical equivalent of heat for 1 kcal or Joule's equivalent is equal to

a) 421 kgm

b) 521 kgm

c) 539 kgm

d) 102 kgm

Q15. Equivalent evaporation of water is the evaporation for a feed water supply at 100°C

a) And its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm2

b) And its corresponding conversion into dry steam at desired boiler pressure

c) Conversion into steam at atmospheric condition

d) Conversion into steam at the same pressure at which feed water is supplied

Q16. The evaporation of 15.653 kg of water per hour from and at 100°C is called

a) Evaporative capacity

b) Factor of evaporation

c) Equivalent evaporation

d) One boiler h.p.

Q17. The increase in pressure

a) Lowers the boiling point of a liquid

b) Raises the boiling point of a liquid

c) Does not affect the boiling point of a liquid

d) Reduces its volume

Q18. During polytropic process

a) Heat transfer takes place across cylinder walls

b) Work is done

c) Steam may be wet, dry or superheated after expansion

d) All of the above

Q19. Hygrometery deals with the

a) Hygroscopic substances

b) Water vapour in air

c) Temperature of air

d) Pressure of air

Q20. Orsat meter is used for

a) Gravimetric analysis of the flue gases

b) Volumetric analysis of the flue gases

c) Mass flow of the flue gases

d) Measuring smoke density of flue gases

Part 32: Objective questions and answers of Thermal Engineering