Refregiration and air Conditioning Quiz Online Questions Test2

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1. Absorption system normally uses the following refrigerant
Freon-11	Freon-22
C02	ammonia

2. One of the purposes of sub-cooling the liquid refrigerant is to _____.
reduce compressor overheating	reduce compressor discharge temperature
increase cooling effect	ensure that only liquid and not the vapour enters the expansion (throttling) valve

3. The value of COP in vapour compression cycle is usually
always less than unity	always more than unity
equal to unity	any one of the above

4. In a refrigeration system, heat absorbed in comparison to heat rejected is _____.
more	less
same	more for small capacity and less for high capacity

5. Condensing temperature in a refrigerator is the temperature
of cooling medium	of freezing zone
of evaporator	at which refrigerant gas becomes liquid

6. Formation of frost on evaporator in refrigerator
results in loss of heat due to poor heat transfer	increases heat transfer rate
is immaterial	can be avoided by proper design

7. In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be _____.
high, of the order of 25°	as low as possible (3 to 11°C)
zero	any value

8. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to ______.
collect liquid refrigerant and prevent it from going to compressor	detect liquid in vapour
superheat the vapour	collect vapours

9. Accumulators should have adequate volume to store refrigerant charge at least _____.
10%	25%
50%	75%

10. At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant
decreases	increases
remains same	depends on other factors

11. 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 _____.
0.2	1.2
5	6

12. Which of the following is not a desirable property of a refrigerant
high triiscibility with oil	low boiling point
good electrical conductor	large latent heat

13. In vapour compression refrigeration system, refrigerant occurs as liquid between
condenser and expansion valve	compressor and evaporator
expansion valve and evaporator	compressor and condenser

14. Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system
strong solution to weak solution	weak solution to strong solution
strong solution to ammonia vapour	ammonia vapour to weak solution

15. Efficiency of a Cornot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle
1.25	0.8
0.5	0.25

16. Highest pressure encountered in a refrigeration system should be ______.
critical pressure of refrigerant	much below critical pressure
much above critical pressure	near critical pressure

17. 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 ______.
0.2	1.2
5	6

18. 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 _____.
Ammonia	Carbon dioxide
Freon	Brine

19. Aqua ammonia is used as refrigerant in the following type of refrigeration system
compression	direct
indirect	absorption

20. If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be _____.
same	more
less	more/less depending on rating

Quiz Refregiration and air Conditioning Online Practice Test1

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1. The moisture in a refrigerant is removed by ____.
evaporator	safety relief valve
dehumidifier	driers

2. The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,
will be higher	will be lower
will remain unaffected	may be higher or lower depending upon the nature of non-condensable gases

3. Critical pressure of a liquid is the pressure
above which liquid will remain liquid	above which liquid becomes gas
above which liquid becomes vapour	above which liquid becomes solid

4. Critical temperature is' the temperature above which
a gas will never liquefy	a gas will immediately liquefy
water will evaporate	water will never evaporate

5. The refrigerant for a refrigerator should have
high sensible heat	high total heat
high latent heat	low latent heat

6. Rating of a domestic refrigerator is of the order of
0.1 ton	5 tons
10 tons	40 tons

7. The COP of a domestic refrigerator
is less than 1	is more than 1
is equal to 1	depends upon the make

8. The domestic refrigerator uses following type of compressor
centrifugal	axial
miniature sealed unit	piston type reciprocating

9. Presence of moisture in a refrigerant affects the working of _____.
compressor	condenser
evaparator	expansion valve

10. Refrigeration in aeroplanes usually employs the following refrigerant
C02	Freon-11
Freon-22	Air

11. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
electrically operated throttling valve	manually operated valve
thermostatic valve	capillary tube

12. Air refrigeration operates on ____.
Carnot cycle	Reversed Carnot cycle
Rankine cycle	Brayton cycle

13. Air refrigeration cycle is used in
domestic refrigerators	commercial refrigerators
air conditioning	gas liquefaction

14. In a vapour compression cycle, the refrigerant immediately after expansion valve is _____.
liquid	sub-cooled liquid
saturated liquid	wet vapour

15. The vapour pressure of refrigerant should be ______.
lower than atmospheric pressure	higher than atmospheric pressure
equal to atmospheric pressure	could be anything

16. For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be
small	high
euqal	anything

17. The bank of tubes at the back of domestic refrigerator are
condenser tubes	evaporator tubes
refrigerant cooling tubes	capillary tubes

18. The higher temperature in vapour compression cycle occurs at _____.
receiver	expansion valve
evaporator	compressor discharge

19. Highest temperature encountered in refrigeration cycle should be _____.
near critical temperature of refrigerant	above critical temperature
at critical temperature	much below critical temperature

20. In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is
less than 2 kg	more than or equal to 3.65 kg
more than 10 kg	there is no such consideration

Refregiration and air Conditioning Online Quiz Questions

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