One of the popular charging devices for artificially cooling food and drink. When the temperature of a blind spot is cooled to below the ambient temperature, that cooling point is called refrigeration.

1. ● Refrigeration and Air Conditioning MCQ Questions
1-One ton of refrigeration is equal to
(A) 21 KJ/min
(B) 105 KJ/min
(C) 210 KJ/min
(D) 420 KJ/min
2-A low side float valve maintains the level of refrigerant in
(A) Flooded evaporator
(B) Evaporator
(C) Condenser
(D) Compressor
3-When wet bulb and dry bulb temperature are equal the humidity is
(A) 60%
(B) 80%
(C) 90%
(D) 100%
4-The refrigerant used in water cooler is
(A) R21
(B) R22
(C) R134a
(D) R717
5-The thermostat used for the window type air conditioner is set at:
(A) 65°F
(B) 75°F
(C) 80°F
(D) 85°F
6-Name the temperature at which moisture condenses on a surface:
(A) Relative humidity
(B) Grains of moisture
(C) Dew point temperature
(D) Humidity
7-A compressor externally coupled to a motor is called
(A) Open type compressor
(B) Semi-sealed compressor
(C) Hermitically sealed compressor
(D) None of the above
8-Brine solution density is checked by
(A) Tachometer
(B) Anemometer
(C) Barometer
(D) Hydrometer
9-Compressor used in Window Air Conditioner is
(A) Rotary compressor
(B) Reciprocating compressor
(C) Sealed compressor
(D) Open type compressor
10-Following is the heart of refrigeration system
(A) Condenser
(B) Evaporator
(C) Compressor
(D) None of the above

2. ANSWERS:
1-(C), 2-(A), 3-(D), 4-(B), 5-(B), 6-(C), 7-(C), 8-(D), 9-(A), 10-(C)
11-An ideal refrigerants is one whose boiling point is
(A) Very high
(B) High
(C) Medium
(D) Low
12-Boiling point of R-600a is
(A) -15.8°C
(B) -14.8°C
(C) -11.8°C (D) -10.8°C
13-Colour code for ammonia refrigerant cylinder is
(A) Light blue
(B) Silver
(C) Orange
(D) Light green
14-The condenser in indirect system, condenses
(A) Oil
(B) Refrigerant
(C) Brine
(D) Water
15-The cooling capacity of 1.0 TR is:
(A) 6000 BTU/Hr
(B) 12000 BTU/Hr
(C) 18000 BTU/Hr
(D) 24000 BTU/Hr
16-Following is the type of zeotropic refrigerant
(A) R-40
(B) R-21
(C) R-407C
(D) R-12
17-High side float valve is fitted on the condensing unit just after the
(A) Receiver
(B) Compressor
(C) Condenser
(D) Evaporator
18-When air is heated relative humidity
(A) Decreases
(B) Increases
(C) Very high
(D) None of the above
19-The Coefficient of Performance (COP) for an air refrigeration system is
(A) Very high
(B) High
(C) Moderate
(D) Low
20-Relay is protection device is used in
(A) Evaporator
(B) Compressor
(C) Condenser
(D) Thermostat ANSWERS:11-
(D), 12-(C), 13-(B), 14-(D), 15-(B), 16-(C), 17-(C), 18-(A), 19-(D), 20-(B)

3. 21-COP of refrigeration is always ___ one.
(A) Equal to
(B) Less than
(C) Greater than
(D) None of the above
22-Commonly used refrigerant in a domestic vapor compression refrigerator is
(A) CO2
(B) Freon-12
(C) Ammonia
(D) SO2
23-The expansion device used in domestic refrigerator:
(A) Capillary tube
(B) Float valve
(C) Hand operated expansion valve
(D) Automatic expansion valve
24-Which of the following is highly toxic and flammable refrigerant?
(A) Carbon di-oxide (B)
Ammonia
(C) Air
(D) R-12
25-When heat is absorbed by a gas, change in entropy is considered to be:
(A) Positive
(B) Zero
(C) Negative
(D) One
26-Which of the following is the azeotrope refrigerant?
(A) R-11
(B) R-40
(C) R-114
(D) R-502
27-The refrigerant commonly used in vapor absorption system is:
(A) Water
(B) Freon-12
(C) SO2
(D) Aqua-ammonia
28-In summer Air conditioning, the air is:
(A) Cooled and humidified
(B) Heated and humidified
(C) Cooled and dehumidified
(D) Heated and dehumidified
29-An Electrolux refrigerator is called:
(A) Single fluid absorption system
(B) Two fluid absorption system
(C) Three fluid absorption system
(D) Four fluid absorption system
30-Commonly used refrigerant in commercial ice plant is:
(A) Ammonia
(B) Freon-12
(C) Air

4. (D) CO2
31-Sling psychrometer is used to measure:
(A) only dry bulb temperature
(B) only wet bulb temperature
(C) dry and wet bulb temperature
(D) relative humidity
32-In refrigeration cycle, oil separator is fitted I between:
(A) Condenser and evaporator
(B) on the suction line
(C) compressor and condenser
(D) at the receiver outlet
33-The following is (are) the required characteristic(s) of refrigerant?
(A) high latent heat
(B) low boiling point
(C) high thermal conductivity
(D) all of the above
34-Accumulator is provided for
(A) storing of unvapourized liquid
(B) storing of liquid refrigerant
(C) exchange of heat
(D) condensing gas
35-HFC should not vent into atmosphere because:
(A) It is flammable in atmospheric temperature
(B) It has high global warming potential
(C) It is highly toxic
(D) It is very costly gas
36-Dehydrator is installed in
(A) liquid line
(B) discharge line
(C) suction line
(D) charging line
37-The difference between DBT and WBT is called:
(A) wet bulb difference
(B) dew point depression
(C) effective temperature
(D) adiabatic saturation temperature
38-Chemical name of Freon-22 is:
(A) Dichloro difluoro methane
(B) Monochloro difluoro methane
(C) Trichloro monofluoro methane
(D) Dicholoro monofluoro methane
39-Crisper temperature of refrigerator is equal to:
(A) 0°C
(B) 8°C
(C) -5°C
(D) None of the above
40-The oil used with R134a refrigerant is:
(A) Mineral oil
(B) Capilla D

5. (C) Polyol ester oil
(D) Lubricating oil
41-Which of the following refrigerant has the highest boiling point?
(A) Carbon di-oxide
(B) Ammonia
(C) Sulphur di-oxide
(D) Freon-12
42-Sum of atmospheric and gauge pressure is called
(A) Total pressure
(B) Absolute pressure
(C) Normal pressure
(D) Natural pressure
43-The effectiveness of the cooling tower is dependent on:
(A) Dry bulb temperature of the air
(B) Direction of the flow of air
(C) Wet bulb temperature of the air
(D) None of the above
ANSWERS:
21-(C), 22-(B),23-(A), 24-(D), 25-(A), 26-(D), 27-(D), 28-(C), 29-(C), 30-(A), 31-(D), 32-(C), 33-
(D), 34-(A), 35-(B), 36-(A), 37-(A), 38-(B), 39-(B), 40-(C), 41-(C), 42-(B), 43-(C)
1-During which component of vapour compression refrigeration system, the enthalpy remains
constant:
(A) Evaporator
(B) Compressor
(C) Throttle valve
(D) None
2-Which one of the following is a CFC refrigerant?
(A) R 744
(B) R 290
(C) R 502
(D) R 718
3-In sensible cooling process the relative humidity:
(A) decreases
(B) increases
(C) remains constant
(D) none of the above
4-In psychrometric chart, dew point temperature lines are
(A) horizontal
(B) vertical
(C) curved
(D) straight lines slopping downwards to the right
5-In psychrometric chart, specific humidity lines are:
(A) vertical
(B) horizontal
(C) inclined

6. (D) curved lines
6-Commonly used refrigerant in commercial ice plant is
(A) CO2
(B) Freon 12
(C) Ammonia
(D) Air
7-Accumulator is provided for
(A) Storing of liquid refrigerant
(B) exchange of heat
(C) storing of unvaporized liquid
(D) condensing gas
8-Oil separator if fitted in between
(A) Condenser and evaporator
(B) On the suction line
(C) compressor and condenser
(D) at the receiver outlet
9-An air washer can work as:
(A) Humidifier
(B) Dehumidifier
(C) Filter
(D) All of the above
10-Sling psychrometer is used to measure
(A) only dry bulb temperature
(B) only wet bulb temperature
(C) dry and wet bulb temperature
(D) relative humidity
ANSWERS:
1-(C), 2-(C), 3-(B), 4-(A), 5-(B), 6-(C), 7-(A), 8-(C), 9-(D), 10-(C)
11-Latent heat of fusion of ice is:
(A) 335 kJ/kg
(B) 144 BTU/lb
(C) 80 kilo-calorie/kg
(D) all of the above
12-Select the wrong characteristics of refrigerant:
(A) low latent heat
(B) low boiling point
(C) high thermal conductivity
(D) none of the above
13-Sensible heat factor is:
(A) Sensible heat/Latent heat
(B) Total heat/Sensible heat

7. (C) Latent heat/Sensible heat
(D) Sensible heat/Total heat
14-The function of duct in air conditioning unit is:
(A) air cooling
(B) air cleaning
(C) air drying
(D) air distribution
15-Process of changing solid into vapour state without passing through liquid state is:
(A) super heating
(B) sublimation
(C) subcooling
(D) triple point
16-Amount of heat required to raise the temperature of one unit of substance through 1 degree
is called:
(A) C.H.U.
(B) B.T.U.
(C) Calorie
(D) Specific heat
17-The COP of a domestic air conditioning in comparison to domestic refrigerator will be:
(A) same
(B) less
(C) more
(D) depends upon weather conditions
18-Solenoid valve is operated:
(A) electrically
(B) by hand
(C) by gas pressure
(D) by oil pressure
19-Subcooling is a process of cooling the refrigerant in vapour compression refrigeration
system before:
(A) evaporation
(B) throttling
(C) condensation
(D) compression
20-Pump down the system for:
(A) more cooling effect
(B) to check compressor efficiency
(C) gas charging
(D) to attend maintenance in low side
ANSWERS:
11-(A), 12-(A), 13-(D), 14-(D), 15-(B), 16-(D), 17-(C), 18-(A), 19-(B), 20-(D)

8. 21-The process in winter air conditioning is
(A) Dehumidification
(B) Heating and humidification
(C) Humidification
(D) Cooling and dehumidification
22-A thermostatic expansion valve function with
(A) suction pressure
(B) discharge pressure
(C) discharge temperature
(D) suction temperature
23-The colour of the flame of halide torch in case of leakage of Freon refrigerant will change t:
(A) Purple
(B) Pink
(C) Bright green
(D) Blue
24-Liquid charged in thermostatic expansion valves sensing bulb is:
(A) alcohol
(B) same refrigerant
(C) mercury
(D) nitrogen
25-The oil used with 134A refrigerant is:
(A) Mineral oil
(B) Capilla D
(C) Polyol ester oil
(D) Lubricating oil
26-The difference between DBT and WBT is called:
(A) wet bulb depression
(B) dew point depression
(C) effective temperature
(D) adiabatic saturation temperature
27-A device which is used to find relative humidity:
(A) Pyrometer
(B) Anemometer
(C) Hydrometer
(D) Hygrometer
28-Which type of valve is used in a reciprocating refrigeration compressor?
(A) rotary valve
(B) poppet valve
(C) ring plate
(D) glob valve
29-The capacity of visible cooler is expressed in:

9. (A) cubic feet
(B) litres
(C) k.cal/TR
(D) tons of refrigeration
30-Chemical name of Freon 22 is
(A) Dichloro difluoro methane
(B) Monochloro difluoro methane
(C) Trichloro monofluoro methane
(D) Dichloro monofluoro methane
ANSWERS:
21-(B), 22-(A), 23-(C), 24-(B), 25-(C), 26-(A), 27-(D), 28-(B), 29-(B), 30-(B)
31-The operation theatre in a hospital is to be air conditioned. Suggest the percentage of
outside air being circulated in the theatre:
(A) zero
(B) 20
(C) 50
(D) 100
32-Which of the following refrigerant has the lowest boiling point?
(A) carbon dioxide
(B) Ammonia
(C) Hydrogen
(D) Freon 12
33-Auto defrost is operated by
(A) Evaporator fan
(B) Thermostat
(C) Timer watch
(D) Heating element
34-The absolute zero temperature corresponds on the condition when
(A) all the substances exit only as solids
(B) volume of a gas reduces to zero
(C) kinetic energy of gas molecules becomes zero
(D) no pressure is exerted by the gas
35-Sum of atmospheric pressure and gauge pressure is called
(A) Total pressure
(B) Absolute pressure
(C) Normal pressure
(D) Natural pressure
36-The effectiveness of the cooling tower is dependent on:
(A) dry bulb temperature of the air
(B) direction of the flow of air
(C) wet bulb temperature of the air
(D) none of the above

10. 37-One micron of vaccum is equal to
(A) 0.1 MM Hg
(B) 0.01 MM Hg
(C) 0.001 MM Hg
(D) 0.0001 MM Hg
38-In a flooded evaporator which of the following types of expansion device is employed?
(A) float valve
(B) capillary tube
(C) automatic expansion valve
(D) thermostatic expansion valve
39-In a thermal electric expansion valve which senses the suction temperature is
(A) Transformer
(B) Thermister
(C) Thermostat
(D) Rheostat
40-The specific humidity is the mass of water vapour present in
(A) 1 kg of dry air
(B) 1 m3 of dry air
(C) 1 m3 of wet air
(D) 1 kg of wet air
ANSWERS:
31-(D), 32-(C), 33-(A), 34-(C), 35-(B), 36-(C), 37-(C), 38-(A), 39-(B), 40-(D)
1-The minimum temperature to which air can be cooled under ideal conditions in evaporative
cooling is
(A) Dew point temperature of the inlet air
(B) Wet bulb temperature of the inlet air
(C) Dry bulb temperature of the inlet air
(D) All of the above
2-For summer air conditioning in coastal regions, the psychometric process employed is
(A) Cooling and humidification
(B) Cooling and dehumidification
(C) Sensible cooling
(D) Sensible heating
3-In psychometric during a sensible cooling, the dew point temperature
(A) Decreases
(B) Increases
(C) May increase and decrease
(D) remains constant
4-It is desirable for a good refrigerant to have
(A) High critical temperature
(B) Low critical temperature

11. (C) High freezing point
(D) High melting point
5-Which of the following is not an ozone friendly refrigerant?
(A) Freon-12
(B) Ammonia
(C) Air
(D) Carbon dioxide
6-In aqua ammonia absorption refrigeration system the refrigerant is
(A) Water
(B) Aqua
(C) Ammonia
(D) Air
7-In vapour compression refrigeration system oil separator is placed between
(A) Compressor and Condenser
(B) Condenser and throttling valve
(C) Throttling valve and evaporator
(D) Evaporator and Compressor
8-In vapour Compression refrigeration system, heat is rejected by the refrigerant in
(A) Compressor
(B) Condenser
(C) Throttle valve
(D) Evaporator
9-Air refrigerator works on
(A) Carnot cycle
(B) Rankine cycle
(C) Brayton cycle
(D) Bell Coleman cycle
10-Which of the following compound is not a refrigerant?
(A) Ammonia
(B) Carbon dioxide
(C) Carbon monoxide
(D) Sulphur dioxide
11-The wet bulb depression is zero when relative humidity equals
(A) 1.0
(B) 0.5
(C) 0.75
(D) zero
12-The following refrigerant is used for refrigeration purposes in passenger aircraft.
(A) Freon-12
(B) Carbon dioxide
(C) Air

12. (D) Sodium chloride
13-One Ton refrigeration is equivalent to
(A) 1 kW
(B) 2.5 kW
(C) 3.5 kW
(D) 5kW
14-The presence of which of the following units in a vapour compression system is adversely
affected by the presence of moisture?
(A) Condenser
(B) Expansion valve
(C) Evaporator
(D) Compressor
15-The ratio of high temperature to low temperature for reversed Carnot refrigeration is 1.25.
The COP will be
(A) 2
(B) 3
(C) 4
(D) 5
16-The colour of flame during halide torch test for refrigerant leaks will change to
(A) Grey
(B) Blue to bright green
(C) Black
(D) Pink or red
17-Bell Coleman cycle is a reversed
(A) Rankine cycle
(B) Otto cycle
(C) Joule cycle
(D) Carnot cycle
17-In in ideal refrigeration cycle, the condenser and evaporator temperature are 27°C and -
13°C respectively. The COP of cycle is.
(A) 6.5
(B) 7.5
(C) 10.5
(D) 15
18-In an absorption refrigeration cycle, the compressor of the vapour compression
refrigeration cycle is replaced by
(A) Liquid pump
(B) Generator
(C) Absorber and generator
(D) Absorber, liquid pump and generator
19-In a vapour absorption refrigerator, heat is rejected in

13. (A) Condenser only
(B) Condenser and absorber
(C) Generator only
(D) Absorber only
20-The atmosphere air at dry bulb temperature of 15°C enters a heating coil maintained at
40°C. The air leaves the heating coil at 25°C. The by-pass factor of the heating coil is
(A) 0.376
(B) 0.4
(C) 0.6
(D) 0.67
ANSWERS:
1-(B), 2-(B), 3-(D), 4-(A), 5-(A), 6-(C), 7-(A), 8-(B), 9-(D), 10-(C), 11-(A), 12-(C), 13-(C), 14-(B),
15-(C), 16-(B), 17-(A), 18-(C), 19-(B), 20-(C)
1-Which of the following refrigerant has lowest freezing temperature?
(A) Carbon dioxide
(B) Ammonia
(C) Freon-12
(D) Freon-22
(Ans: D)
2-The working fluid in Bell Coleman cycle is
(A) Freon-12
(B) Carbon dioxide
(C) Ammonia
(D) Air
(Ans: D)
3-In a vapour compression system, the compression of refrigerant follows the law
(A) PVr = C
(B) PV = C
(C) PVn = C
(D) None of the above
(Ans: C)
4-The dry bulb temperature lines of psychometric chart are
(A) Vertical
(B) Horizontal
(C) Inclined
(D) Curved
(Ans: A)
5-When the lower temperature is fixed, COP of a refrigerating machine can be improved by
(A) operating the machine at higher speeds
(B) operating the machine at lower speeds
(C) raising the higher temperature
(D) lowering the higher temperature
(Ans: D)

14. 6-Evaporative air-cooler is used effectively when
(A) dry bulb temperature is very close to the wet bulb temperature
(B) dry bulb temperature is high and relative humidity is high
(C) dry bulb temperature is low and relative humidity is high
(D) dry bulb temperature is high and the relative humidity is low
(Ans: D)
7-Refrigerant Freon 12 belongs to
(A) methane family
(B) ethane family
(C) ketone family
(D) aldehyde family
(Ans: A)
8-Sometimes refrigerant plants use cooling towers. The water cooled in these towers is used
(A) for defrosting evaporator coils
(B) to cool compressor cylinder only
(C) to cool the evaporator coils
(D) to cool refrigerant in condenser
(Ans: D)
9-The statements concern Psychometric chart.
I-Constant relative humidity lines are uphill straight lines to the right
II-Constant wet bulb temperature lines are downhill straight lines to the right
III-Constant specific volume lines are downhill straight lines to the right
IV-Constant enthalpy lines are coincident with constant wet bulb temperature lines
Which of the statements are correct?
(A) II and II
(B) I and II
(C) I and III
(D) II and IV
(Ans: D)
10-In S.I. unit, one tonne of refrigeration is equal to
(A) 110 kJ/min
(B) 210 kJ/min
(C) 50 kJ/min
(D) non of the above
(Ans: B)
11-Subcooling occurs when the vapour
(A) has high latent heat
(B) removes sensible heat from refrigerant
(C) has low latent heat
(D) has high thermal conductivity
(Ans: B)
12-The refrigerant used in vapour absorption refrigerator is

15. (A) Freon-12
(B) Ammonia
(C) CO2
(D) Aqua-ammonia
(Ans: D)
13-In a window air conditioner, the expansion device used is
(A) Capillary tube
(B) Thermostatic expansion valve
(C) Automatic expansion valve
(D) Float valve
(Ans: A)
14-Formula for R134a refrigerant is
(A) CH Cl F2
(B) C2 Cl3 F3
(C) C2 Cl2 F4
(D) C2 H2 F4
(Ans: D)
A domestic refrigerator, set at 2°C, handles on an average a thermal load of 8000 kJ per day.
The ambient temperature is 30°C and the COP of the refrigerator is 0.15 times that of a Carnot
refrigerator. The daily electricity consumption in kWh is approximately
(a) 1.47
(b) 1.51
(c) 3.28
(d) 2.86
(Ans:b)
COP of a reversed Carnot cycle refrigerator working between higher temperature T2 and
lower temperature T1
(a) will increase with increase in T1 keeping T2 fixed
(b) will decrease with increase in T1 keeping T2 fixed
(c) will first increase with increase in T1 and then decrease with increase in T1 keeping T2 fixed
(d) none of the above
(Ans:a)
A refrigerating machine working on reversed carnot cycle takes out 2kW of heat from the cold
body while working between the temperature limits of 300K and 200K. The COP and power
consumed by the cycle will be respectively.
(a) 1 and 1kW
(b) 1 and 2kW
(c) 2 and 1kW
(d) 2 and 2kW
(Ans:c)
A 1 ton capacity water cooler cools water steadily from 35°C to 20°C. The specific heat of water
is 4.18 kj/kg-K. The water flow rate will be nearly.
(a) 13.33 liter/hr
(b) 33.3 liter/hr

16. (c) 200 liter/hr
(d) 250 liter/hr
(Ans:c)
Consider the following statements:
Dry compression in reciprocating compressor is preferred it
prevents valve damage
enables use of thermostatic expansion valve
minimizes irreversibility in the compressor
prevents washing out of the lubricating oil from cylinder walls
Which of these statements is correct?
(a) 1 and 2
(b) 2 and 3
(c) 1 and 4
(d) 3 and 4
(Ans:c)
Sub-cooling heat exchanger is used in a refrigeration cycle. The enthalpies at condenser outlet
and evaporator outlet are 78kJ/kg and 182 kJ/kg respectively. The enthalpy at outlet of
isentropic compressor is 230kJ/kg and enthalpy of sub cooled liquid is 68kJ/kg. The COP of the
cycle is
(a) 3.25
(b) 2.16
(c) 3.0
(d) 3.5
(Ans:c)
Waste heat can be effectively used in which one of the following refrigeration systems?
(a) vapour compression refrigeration cycle
(b) air refrigeration cycle
(c) vapour absorption refrigeration cycle
(d) vortex refrigeration cycle
(Ans:c)
In vapour absorption refrigeration system, heat is rejected in
(a) condenser only
(b) generator only
(c) absorber only
(d) condenser and absorber
(Ans:d)
An Electrolux refrigerator uses
(a) one pump
(b) two pump
(c) no pump
(d) three pump
(Ans:c)

17. Which one of the following refrigerants has the highest critical temperature?
(a) H2O
(b) CO2
(c) R-12
(d) NH3
(Ans:a)
Dew point temperature is the temperature at which condensation begins when air is cooled at
constant
(a) volume
(b) entropy
(c) pressure
(d) enthalpy
(Ans:c)
The main process which takes place in a dessert cooler is
(a) sensible cooling
(b) dehumidification
(c) adiabatic saturation
(d) cooling and dehumidification
(Ans:c)
A domestic refrigerator, set at 2°C, handles on an average a thermal load of 8000 kJ per day.
The ambient temperature is 30°C and the COP of the refrigerator is 0.15 times that of a Carnot
refrigerator. The daily electricity consumption in kWh is approximately
(a) 1.47
(b) 1.51
(c) 3.28
(d) 2.86
(Ans:b)
COP of a reversed Carnot cycle refrigerator working between higher temperature T2 and
lower temperature T1
(a) will increase with increase in T1 keeping T2 fixed
(b) will decrease with increase in T1 keeping T2 fixed
(c) will first increase with increase in T1 and then decrease with increase in T1 keeping T2 fixed
(d) none of the above
(Ans:a)
A refrigerating machine working on reversed carnot cycle takes out 2kW of heat from the cold
body while working between the temperature limits of 300K and 200K. The COP and power
consumed by the cycle will be respectively.
(a) 1 and 1kW
(b) 1 and 2kW
(c) 2 and 1kW
(d) 2 and 2kW
(Ans:c)
A 1 ton capacity water cooler cools water steadily from 35°C to 20°C. The specific heat of water
is 4.18 kj/kg-K. The water flow rate will be nearly.

18. (a) 13.33 liter/hr
(b) 33.3 liter/hr
(c) 200 liter/hr
(d) 250 liter/hr
(Ans:c)
Consider the following statements:
Dry compression in reciprocating compressor is preferred it
prevents valve damage
enables use of thermostatic expansion valve
minimizes irreversibility in the compressor
prevents washing out of the lubricating oil from cylinder walls
Which of these statements is correct?
(a) 1 and 2
(b) 2 and 3
(c) 1 and 4
(d) 3 and 4
(Ans:c)
Sub-cooling heat exchanger is used in a refrigeration cycle. The enthalpies at condenser outlet
and evaporator outlet are 78kJ/kg and 182 kJ/kg respectively. The enthalpy at outlet of
isentropic compressor is 230kJ/kg and enthalpy of sub cooled liquid is 68kJ/kg. The COP of the
cycle is
(a) 3.25
(b) 2.16
(c) 3.0
(d) 3.5
(Ans:c)
Waste heat can be effectively used in which one of the following refrigeration systems?
(a) vapour compression refrigeration cycle
(b) air refrigeration cycle
(c) vapour absorption refrigeration cycle
(d) vortex refrigeration cycle
(Ans:c)
In vapour absorption refrigeration system, heat is rejected in
(a) condenser only
(b) generator only
(c) absorber only
(d) condenser and absorber
(Ans:d)
An Electrolux refrigerator uses
(a) one pump
(b) two pump
(c) no pump
(d) three pump

19. (Ans:c)
Which one of the following refrigerants has the highest critical temperature?
(a) H2O
(b) CO2
(c) R-12
(d) NH3
(Ans:a)
Dew point temperature is the temperature at which condensation begins when air is cooled at
constant
(a) volume
(b) entropy
(c) pressure
(d) enthalpy
(Ans:c)
The main process which takes place in a dessert cooler is
(a) sensible cooling
(b) dehumidification
(c) adiabatic saturation
(d) cooling and dehumidification
(Ans:c)