Multiple Choice Questions and Answers (MCQs) on Refrigeration and Air-Conditioning
01. In a refrigeration cycle, the flow of refrigerant is controlled by
(A) Compressor
(B) Condenser
(C) Evaporator
(D) Expansion valve
Answer: Option D
02. The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to
(A) Bright green
(B) Yellow
(C) Red
(D) Orange
Answer: Option A
03. For air conditioning the operation theatre in a hospital, the percentage of outside air in the air supplied is
(A) Zero
(B) 20
(C) 50
(D) 100
Answer: Option D
04. In vapour compression cycle using NH₃ as refrigerant, initial charge is filled at
(A) Suction of compressor
(B) Delivery of compressor
(C) High pressure side close to receiver
(D) Low pressure side near receiver
Answer: Option C
05. The temperature of air recorded by a thermometer, when it is not affected by the moisture present in the air, is called
(A) Wet bulb temperature
(B) Dry bulb temperature
(C) Dew point temperature
(D) None of these
Answer: Option B
06. Absorption system normally uses the following refrigerant
(A) Freon-11
(B) Freon-22
(C) CO2
(D) Ammonia
Answer: Option D
07. Which of the following statement is correct?
(A) In vapour absorption refrigerator, the compression of refrigerant is avoided.
(B) Sub-cooling can be achieved by circulating more quantity of cooling water through the condenser.
(C) In vapour compression refrigeration, the vapour is drawn in the compressor cylinder during its suction stroke and is compressed adiabatically during the compression stroke.
(D) All of the above
Answer: Option D
08. Allowable pressure on high pressure side or ammonia absorption system is of the order of
(A) Atmospheric pressure
(B) Slightly above atmospheric pressure
(C) 24 bars
(D) 56 bars
Answer: Option D
09. The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.
(A) Same
(B) Lower
(C) Higher
(D) None of these
Answer: Option C
10. Chaperon equation is a relation between
(A) Temperature, pressure and enthalpy
(B) Specific volume and enthalpy
(C) Temperature and enthalpy
(D) Temperature, pressure, specific volume and enthalpy
Answer: Option D
11. During humidification process, __________ increases.
(A) Wet bulb temperature
(B) Relative humidity
(C) Dry bulb temperature
(D) Specific humidity
Answer: Option B
12. Where does the lowest temperature occur in a vapour compression cycle?
(A) Condenser
(B) Evaporator
(C) Compressor
(D) Expansion valve
Answer: Option B
13. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called
(A) Humidity ratio
(B) Relative humidity
(C) Absolute humidity
(D) Degree of saturation
Answer: Option B
14. Under cooling in a refrigeration cycle
(A) Increases C.O.P
(B) Decreases C.O.P
(C) C.O.P remains unaltered
(D) Other factors decide C.O.P
Answer: Option A
15. In a domestic vapour compression refrigerator, the refrigerant commonly used is
(A) CO₂
(B) Ammonia
(C) R-12
(D) All of these
Answer: Option C
16. 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
Answer: Option A
17. 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: Option C
18. 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
Answer: Option D
19. The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is
(A) High pressure saturated liquid
(B) Wet vapour
(C) Very wet vapour
(D) Dry vapour
Answer: Option C
20. 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
Answer: Option B
21. The centrifugal compressors are generally used for refrigerants that require
(A) Small displacements and low condensing pressures
(B) Large displacements and high condensing pressures
(C) Small displacements and high condensing pressures
(D) Large displacements and low condensing pressures
Answer: Option D
22. Rick up the incorrect statement
(A) Lithium bromide used in vapour absorption cycle is non volatile
(B) Lithium bromide plant can’t operate below 0°C
(C) A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing
(D) Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator
Answer: Option C
23. During dehumidification process, the relative humidity
(A) Remains constant
(B) Increases
(C) Decreases
(D) None of these
Answer: Option C
24. The refrigerant widely used in domestic refrigerators is
(A) Ammonia
(B) Carbon dioxide
(C) Sulphur dioxide
(D) R-12
Answer: Option D
25. The moisture in a refrigerant is removed by
(A) Evaporator
(B) Safety relief valve
(C) Dehumidifier
(D) Driers
Answer: Option D