Practice Test: Question Set - 08
1. The value of C.O.P in vapour compression cycle is usually
- (A) Always less than
unity
- (B) Always more than
unity
- (C) Equal to unity
- (D) Any one of the above
2. The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)
- (A) T₁ / (T₂ - T₁)
- (B) (T₂
- T₁)/T₁
- (C) (T₁ - T₂)/T₁
- (D) T₂/ (T₂ - T₁)
3. Which of the following is not a desirable property of a refrigerant?
- (A) High risibility with
oil
- (B) Low boiling point
- (C) Good electrical
conductor
- (D) Large latent heat
4. The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called
- (A) Sub-cooling
or under-cooling
- (B) Super-cooling
- (C) Normal
cooling
- (D) None
of these
5. A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is
- (A) Ammonia
- (B) Carbon dioxide
- (C) Freon
- (D) Brine
6. The capillary tube, as an expansion device, is used in
- (A) Domestic
refrigerators
- (B) Water
coolers
- (C) Room
air conditioners
- (D) All
of these
7. If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of -23°C, then the Carnot COP will be
- (A) 0.2
- (B) 1.2
- (C) 5
- (D) 6
8. Which of the following statement is correct?
- (A) The
human body can lose heat even if its temperature is less than the atmospheric
temperature.
- (B) The increase
in air movement increases the evaporation from the human body.
- (C) The warm air
increases the rate of radiation of heat from the human body.
- (D) Both (A) and
(B)
9. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to
- (A) Collect liquid refrigerant and prevent it
from going to compressor
- (B) Detect liquid in
vapour
- (C) Superheat the vapour
- (D) Collect vapours
10. The minimum temperature to which water can be cooled in a cooling tower is
- (A) Dew point
temperature of air
- (B) Wet
bulb temperature of air
- (C) Dry bulb
temperature of air
- (D) Ambient air
temperature
11. Highest temperature encountered in refrigeration cycle should be
- (A) Near critical
temperature of refrigerant
- (B) Above critical
temperature
- (C) At critical Temperature
- (D) Much below critical
temperature
12. The operating pressure for refrigerating units using R-12 as a refrigerant is
- (A) 2 bar
- (B) 8 bar
- (C) 15 bar
- (D) 30 bar
13. The domestic refrigerator uses following type of compressor
- (A) Centrifugal
- (B) Axial
- (C) Miniature sealed unit
- (D) Piston type reciprocating
14. A bootstrap air cooling system has
- (A) One heat
exchanger
- (B) Two
heat exchangers
- (C) Three
heat exchangers
- (D) Four
heat exchangers
15. Critical temperature is the temperature above which
- (A) A gas will never
liquefy
- (B) A gas will
immediately liquefy
- (C) Water will evaporate
- (D) Water will never
evaporate
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