Heat Transfer 6

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Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Heat Transfer 6

Part 6: List for questions and answers of Heat Transfer

Q1.The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called
a) Wet bulb temperature
b) Dry bulb temperature
c) Dew point temperature
d) None of these

Q2. If the energy radiated per second per sq. Cm. Of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
a) Absorptive power
b) Emissive power
c) Emissivity
d) None of these

Q3.In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
a) Heated and dehumidified
b) Heated and humidified
c) Cooled and humidified
d) Cooled and dehumidified

Q4.A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called
a) Automatic expansion valve
b) High side float valve
c) Thermostatic expansion valve
d) Low side float valve

Q5.The emissivity of a polished silver body is __________ as compared to black body
a) Same
b) Low
c) Very low
d) High

Q6.The ratio of heat extracted in the refrigerator to the work done on the refrigerant is called
a) Coefficient of performance of refrigeration
b) Coefficient of performance of heat pump
c) Relative coefficient of performance
d) Refrigerating efficiency

Q7.Air refrigerator works on
a) Reversed Carnot cycle
b) Bell Coleman cycle
c) Both (a) and ib)
d) None of these

Q8.The reciprocating refrigerant compressors are very suitable for
a) Small displacements and low condensing pressures
b) Large displacements and high condensing pressures
c) Small displacements and high condensing pressures
d) Large displacements and low condensing pressures

Q9.The cooling system used for supersonic aircrafts and rockets is
a) Simple air cooling system
b) Boot-strap air cooling system
c) Reduced ambient air cooling system
d) Regenerative air cooling system

Q10.The desirable property of a refrigerant is
a) Low boiling point
b) High critical temperature
c) High latent heat of vaporisation
d) All of these

Q11.The colour of the flame of halide torch, in case of leakage of freon refrigerant, will change to
a) Bright green
b) Yellow
c) Red
d) Orange

Q12.The humidification process, on the psychrometric chart is shown by
a) Horizontal line
b) Vertical line
c) Inclined line
d) Curved line

Q13.The refrigerant widely used in domestic refrigerators is
a) Ammonia
b) Carbon dioxide
c) Sulphur dioxide
d) R-12

Q14.The critical temperature is the temperature
a) Below which a gas does not obey gas laws
b) Above which a gas may explode
c) Below which a gas is always liquified
d) Above which a gas will never liquified

Q15.The evaporator changes the low pressure liquid refrigerant from the expansion valve into
a) High pressure liquid refrigerant
b) Low pressure liquid and vapour refrigerant
c) Low pressure vapour refrigerant
d) None of these

Q16.Most thermostatic expansion valves are set for a superheat of
a) 5 deg. C
b) 10 deg. C
c) 15 deg. C
d) 20 deg. C

Q17.The transfer of heat by molecular collision is smallest in
a) Solids
b) Liquids
c) Gases
d) None of these

Q18.In a shell and tube heat exchanger, baffles are provided on the shell side to
a) Improve heat transfer
b) Provide support for tubes
c) Prevent stagnation of shell side fluid
d) All of these

Q19.In aqua-ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in
a) Condenser
b) Evaporator
c) Absorber
d) None of these

Q20.Wet bulb temperature is the temperature of air recorded by a thermometer, when
a) It is not effected by the moisture present in the air
b) Its bulb is surrounded by a wet cloth exposed to the air
c) The moisture present in it begins to condense
d) None of the above

Part 6: List for questions and answers of Heat Transfer

Q1. Answer: a

Q2. Answer: b

Q3. Answer: b

Q4. Answer: d

Q5. Answer: c

Q6. Answer: a

Q7. Answer: c

Q8. Answer: c

Q9. Answer: d

Q10. Answer: d

Q11. Answer: a

Q12. Answer: b

Q13. Answer: d

Q14. Answer: d

Q15. Answer: c

Q16. Answer: a

Q17. Answer: c

Q18. Answer: d

Q19. Answer: a

Q20. Answer: b