MCQ on Refrigeration and Air Conditioning
1- In vapor compression refrigeration system, liquid-to-suction heat exchanger is used to
(A) Keep the COP constant
(B) Prevent the liquid refrigerant from entering the compressor
(C) Sub-cool the liquid refrigerant leaving the condenser
(D) Sub-cool the vapor refrigerant from the evaporator
2- Wet bulb depression, under saturated ambient air conditions
(A) is always positive
(B) is always negative
(C) is always zero
(D) may have a value depending upon the new point temperature
3- Which of the following cycles uses air as the refrigerant?
(A) Ericsson
(B) Stirling
(C) Carnot
(D) Bell-Coleman
4- Ammonia-absorption refrigeration cycle requires
(A) very little work input
(B) maximum work input
(C) nearly same work input as for vapor compression cycle
(D) zero work input
5- In vapor compression cycle the condition of refrigerant is super-heated vapor
(A) after passing through the condenser
(B) before passing through the condenser
(C) after passing through the expansion or throttle valve
(D) before entering the expansion valve
6- The vapor compression refrigerator employs the following cycle
(A) Rankine
(B) Carnot
(C) Reversed Rankine
(D) Reversed Carnot
7- Refrigeration in aero-planes usually employs the following refrigerant
(A) Carbon Di-oxide
(B) Freon-11
(C) Freon-22
(D) Air
8- In electro-lux refrigerator there is no
(A) Electricity required
(B) Moving machinery
(C) Noise
(D) All of the above
9- The process in which after condensation the refrigerant is cooled below the saturation temperature before throttling, is known as
(A) Sub cooling
(B) Super cooling
(C) Normal cooling
(D) None of the above
10- Evaporating pressure of the refrigerant as compared to atmospheric pressure is
(A) More
(B) Equal
(C) Less
(D) None of the above
11- In sensible cooling process of air, specific humidity
(A) Increases
(B) Decreases
(C) Remains constant
(D) None of the above
12- In psychrometric chart, the humidification process is indicated by
(A) Vertical line
(B) Horizontal line
(C) Inclined line
(D) Curved line
13- The process used for winter air conditioning is
(A) Heating and humidification
(B) Humidification and de-humidification
(C) Heating and de-humidification
(D) Cooling humidification
14- In vapor compression system, the highest temperature of the refrigerant during the cycle occurs after
(A) Evaporation
(B) Condensation
(C) Expansion
(D) Compression
15- Frosting of evaporator tubes results in
(A) Increased heat transfer rate
(B) Decreased heat transfer rate
(C) Increased compressor pressure
(D) Decreased compressor pressure
16- In a simple vapor compression cycle. The refrigerant is in the form of dry saturated vapor before entering:
(A) Condenser
(B) Evaporator
(C) Throttle valve
(D) Compressor
17- In throttling process, which property is constant?
(A) Enthalpy
(B) Entropy
(C) Pressure
(D) Volume
18- In psychometric chart, Wet bulb temperature lines are:
(A) Horizontal
(B) Vertical
(C) Inclined
(D) Curved
19- The COP of vapor compression refrigeration system is _______ than air refrigeration system:
(A) Greater
(B) Lower
(C) Equal
(D) Cannot be predicted
20- Bell- Coleman cycle is the base of following refrigeration system:
(A) Air refrigeration system
(B) Steam jet refrigeration system
(C) Vapor compression refrigeration system
(D) Absorption refrigeration system
21- The net effect of under cooling in vapor compression refrigeration system is:
(A) To decrease COP
(B) COP remains unaffected
(C) To increase COP
(D) COP may increase or decrease
22- The temperature measured by the thermometer when its bulb is covered with wet cloth and is exposed to a current of moving air:
(A) Dry bulb temperature
(B) Wet bulb temperature
(C) Dew bulb temperature
(D) Dew point temperature
23- The enthalpy of moist air is given as:
(A) Enthalpy of dry air only
(B) Enthalpy of water vapor only
(C) Sum of A and B
(D) Cannot be obtained by summation
24- In psychometric chart, the following is taken along abscissa:
(A) Dry bulb temperature
(B) Wet bulb temperature
(C) Specific humidity
(D) Dew point temperature
25- During sensible heating:
(A) Moisture is removed
(B) Moisture is added
(C) Heating without addition or subtraction of moisture
(D) Heating with addition of moisture
26- In the window air conditioner, the expansion device used is
(A) float valve
(B) thermostatic expansion valve
(C) automatic expansion valve
(D) capillary tube
ANSWERS:
1-(B), 2-(C), 3-(D), 4-(A), 5-(B), 6-(C), 7-(D), 8-(D), 9-(A), 10-(C), 11-(C), 12-(A), 13-(A), 14-(D), 15-(B), 16-(D), 17-(A), 18-(C), 19-(A), 20-(A), 21-(C), 22-(B), 23-(C), 24-(A), 25-(C), 26-(D)