Refrigeration and Air-Conditioning Online Practice Tests - Set 05

Practice Test: Question Set - 05

1. Dry bulb temperature is the temperature of air recorded by a thermometer, when
    (A) It is not affected 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

2. In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be
    (A) High, of the order of 25°
    (B) As low as possible (3 to 11°C)
    (C) Zero
    (D) Any value

3. 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

4. Choose the correct statement
    (A) A refrigerant should have low latent heat
    (B) If operating temperature of system is low, then refrigerant with low boiling point should be used
    (C) Pre-cooling and sub-cooling bf refrigerant are same
    (D) Superheat and sensible heat of a refrigerant are same

5. Carbon dioxide is
    (A) Colourless
    (B) Odourless
    (C) Non-flammable
    (D) All of these

6. Reducing suction pressure in refrigeration cycle
    (A) Lowers evaporation temperature
    (B) Increases power required per ton of refrigeration
    (C) Lowers compressor capacity because vapour is lighter
    (D) All of the above

7. The coefficient of performance of a domestic refrigerator is ________ as compared to a domestic air-conditioner.
    (A) Same
    (B) Less
    (C) More
    (D) None of these

8. If a gas is to be liquefied, its temperature must be
    (A) Increased to a value above its critical temperature
    (B) Reduced to a value below its critical temperature
    (C) Equal to critical temperature
    (D) None of the above

9. The capacity of a domestic refrigerator is in the range of
    (A) 0.1 to 0.3 TR
    (B) 1 to 3 TR
    (C) 3 to 5 TR
    (D) 5 to 7 TR

10. The lowest thermal diffusivity is of
    (A) Iron
    (B) Lead
    (C) Aluminium
    (D) Rubber

11. In a vapour compression cycle, the refrigerant immediately after expansion valve is
    (A) Liquid
    (B) Sub-cooled liquid
    (C) Saturated liquid
    (D) Wet vapour

12. Which of the following statement is correct for ammonia as a refrigerant?
    (A) It is toxic to mucous membranes.
    (B) It requires large displacement per TR compared to fluoro carbons.
    (C) It reacts with copper and its alloys.
    (D) All of these

13. Critical pressure of a liquid is the pressure
    (A) Above which liquid will remain liquid
    (B) Above which liquid becomes gas
    (C) Above which liquid becomes vapour
    (D) Above which liquid becomes solid

14. The optimum effective temperature for human comfort is
    (A) Higher in winter than in summer
    (B) Lower in winter than in summer
    (C) Same in winter and summer
    (D) Not dependent on season

15. Formation of frost on evaporator in refrigerator
    (A) Results in loss of heat due to poor heat transfer
    (B) Increases heat transfer rate
    (C) Is immaterial
    (D) Can be avoided by proper design

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