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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