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Free download in PDF Refrigeration and Air Conditioning Short Questions and Answers for competitive exams. These short objective type questions with answers are very important for competitive exams. These short solved questions or quizzes are provided by Gkseries.
41
Which of the following is not a desirable property of a refrigerant
[A]
high triiscibility with oil
[B]
low boiling point
[C]
good electrical conductor
[D]
large latent heat
Answer: good electrical conductor
42
A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of- 23°C. The Cannot coefficient of performance of cycle will be
[A]
0.2
[B]
1.2
[C]
5
[D]
6
43
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant
[A]
decreases
[B]
increases
[C]
remains same
[D]
depends on other factors
44
Accumulators should have adequate volume to store refrigerant charge at least
[A]
10%
[B]
25%
[C]
50%
[D]
75%
45
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]
collect vapours
[D]
superheat the vapour
Answer: collect liquid refrigerant and prevent it from going to compressor
46
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
Answer: as low as possible (3 to 11°C)
47
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
Answer: results in loss of heat due to poor heat transfer
48
Condensing temperature in a refrigerator is the temperature
[A]
of cooling medium
[B]
of freezing zone
[C]
of evaporator
[D]
at which refrigerant gas becomes liquid
Answer: at which refrigerant gas becomes liquid
49
In a refrigeration system, heat absorbed in comparison to heat rejected is
[A]
more
[B]
less
[C]
same
[D]
more for small capacity and less for high capacity
50
The value of COP 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
Answer: always more than unity
51
One of the purposes of sub-cooling the liquid refrigerant is to
[A]
reduce compressor overheating
[B]
reduce compressor discharge temperature
[C]
increase cooling effect
[D]
ensure that only liquid and not the vapour enters the expansion (throttling) valve
Answer: ensure that only liquid and not the vapour enters the expansion (throttling) valve
52
Absorption system normally uses the following refrigerant
[A]
Freon-11
[B]
ammonia
[C]
Freon-22
[D]
C02
53
An important characteristic of absorption system of refrigeration is
[A]
Noisy operation
[B]
Quiet operation
[C]
Cooling below 0°C
[D]
Very little power consumption
54
Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
[A]
Electrically operated throttling valve
[B]
Manually operated valve
[C]
Thermostatic valve
[D]
Capillary tube
55
The fluids used in Electrolux refrigerator are
[A]
Water and hydrogen
[B]
Ammonia and hydrogen
[C]
Ammonia, water and hydrogen
[D]
None of these
Answer: Ammonia, water and hydrogen
56
The COP of a vapour compression plant in comparison to vapour absorption plant is
[A]
More
[B]
Less
[C]
Same
[D]
More/less depending on size of plant
57
In a lithium bromide absorption refrigeration system
[A]
Lithium bromide is used as a refrigerant and water as an absorbent
[B]
Water is used as a refrigerant and lithium bromide as an absorbent
[C]
Ammonia is used as a refrigerant and lithium bromide as an absorbent
[D]
None of these
Answer: Water is used as a refrigerant and lithium bromide as an absorbent
58
The bank of tubes at the back of domestic refrigerator is
[A]
Condenser tubes
[B]
Evaporator tubes
[C]
Refrigerant cooling tubes
[D]
Capillary tubes
59
The vapour compression refrigerator employs the following cycle
[A]
Rankine
[B]
Carnot
[C]
Reversed Rankine
[D]
Reversed Carnot
60
In a refrigeration system, the expansion device is connected between the
[A]
Compressor and condenser
[B]
Condenser and receiver
[C]
Receiver and evaporator
[D]
Evaporator and compressor
Answer: Receiver and evaporator
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