2016 JULY REFRIGERATION AND AIR CONDITIONING THEORY SEMESTER-II
1. The compressor motor in
a hermetically sealed compressor
is cooled by ............
a) Water
b) Air
c) Refrigerant
d) Nitrogen
Answer:- b) Air
2. The screw compressors can be
used for wet compression with
refrigerant -
a) R134a
a) R134a
b) R12
c) NH3
d) Water
Answer:- c) NH3
3. For large capacity and high
volume flow rate the suitable
compressor is ............
a) Centrifugal
a) Centrifugal
b) Reciprocating
c) Screw
d) Scroll
Answer:- a) Centrifugal
4. The main components of a
centrifugal compressor are .....
a) Eye
b) Impeller
c) Diffuser
d) Both (a) & (b)
Answer:- d) Both (a) & (b)
5. The slip in case of three
phase induction motor is in
the range of.........
a) 0.5% to 5%
b) 2% to 10%
c) 10% to 15%
d) 15% to 20%
Answer:- a) 0.5% to 5%
6. High starling torque induction
motors for compressors are
used with .............
a) Capillary tube
b) Condenser
c) Float valves
d) None of these
Answer:- d) None of these
7. The relationship between
rotor speed 'N' frequency 'F'and no.
of poles 'P' is given by
the relation ...........
the relation ...........
a) N=120t7P
b) PN=120/f
c) f=120N/P
d) N=l20P/f
Answer:- a) N=120t7P
8. The function of condenser
in a refrigeration system is ..........
a) To cool surrounding air
b) To cool products or space
c) To condense the superheated
vapor refrigerant discharged by
the compressor
d) To condense the refrigerant
vapour entering the compressor
Answer:- c) To condense the superheated
vapor refrigerant discharged by
the compressor
9. Domestic refrigeration work on .....
a) Vapour compression cycle
b) Vapour absorption
c) Otto cycle
d) None of these
Answer:- a) Vapour compression cycle
10. Liquid receiver is installed in -
a) Suction line
b) Discharge line
c) Liquid line
d) Expansion line
Answer:- c) Liquid line
11. The efficiency of a water cooled
condenser is ......
a) Lower than the air cooled condenser
b) Same as that of air cooled condenser
c) Higher than the air cooled condenser
c) Higher than the air cooled condenser
d) None of these
Answer:- c) Higher than the air cooled condenser
12. The function of drier in a refrigeration
system is to ............
a) Separate lubricant from the refrigerant
b) Remove the moisture from the refrigerant
a) Separate lubricant from the refrigerant
b) Remove the moisture from the refrigerant
c) To maintain the level of the liquid
refrigerant in the system
d) Help in dry compression of the refrigerant
Answer:- b) Remove the moisture from the refrigerant
13. The dry compression can be
avoided by installing -
a) Liquid suction heat exchanger
b) Accumulator
c) Thermostatic expansion valve
d) All of these methods can be used
Answer:- d) All of these methods can be used
14. The length and diameter of
capillary tube are -
a) Small
b) Large
c) Small and large respectively
d) Long and small
Answer:- d) Long and small
15. The expansion valve used in
central air-conditioning plant
should be
a) Capillary tube
b) Thermostatic expansion valv
c) Automatic expansion valve
d) Low side float valve
Answer:- b) Thermostatic expansion valv
16. The drawback of automatic
expansion valve is ............
a) Increase in load increases the
mass flow rate
b) Increase in load decreases
mass flow rate
c) Not suitable for varying load
d) Both (a) and (c)
Answer:- d) Both (a) and (c)
17. During expansion in capillary tube
enthalpy ........
a) Increase
b) Decrease
c) Not change
d) None of these
Answer:- c) Not change
18. Temporary fastening done by
help of..............
a) Welding
b) Brazing
c) Soldering
d) Rivet
Answer:- d) Rivet
19. The power consumption of a
1TR window AC is in the
range of..........
a) 1 to 1.5 kW
b) 1.5 to 2 kW
c) 2kW to2.5kW
d) 3to3.5kW
Answer:- c)2kW to2.5kW
20. Superheating in evaporator
causes ...........
a) Capacity to increase
b) Compressor power consumption to
c) COP to increase only
d) Both (a) and (b)
Answer:- b) Compressor power consumption to
21. The HFC refrigerants have ........
a) Low ODP value
b) High OPD
c) Low GWP
d) Zero ODP
Answer:- d) Zero ODP
22. The HCFC refrigerant is -
a) R12
b) R22
c) R134a
d) R600
Answer:- b) R22
23. The HFC refrigerant is -
a) RH
b) R22
c) R134a
d) R290
Answer:- c) R!34a
24. The main drawback of HC
refrigerants is their
a) High ODP
b) High GWP
c) Flammability
d) High GWP and Flammability
Answer:- c) Flammability
25. The alternate refrigerant for
R l 1 is ...........
a) R22
b) R123
c) R134a
d) R125
Answer:- b) R123
26. Window AC for cooling can be
easily converted to heating mode
by installing a .........
a) Two way reversing valve
a) Two way reversing valve
b) Four way reversing valve
c) Throttle valve
d) Three way valve
Answer:- b) Four way reversing valve
27. Brine is a solution of .........
a) Ice and water
b) water and sodium chloride
c) Water and acid
d) None of these
Answer:- b) water and sodium chloride
28. In the condenser, the
refrigerant first loses its ........
a) Latent heat
b) Sensible heat
c) Sometimes sensible and
sometimes latent heat
d) None of these
Answer:- b) Sensible heat
29. The pipe line pressure drops
in split AC are more compared to
window AC because of-
a) Long length of suction and
discharge lines
b) Two units i.e. indoor and
outdoor units
c) Long length of discharge and
liquid line
d) Long lengths of suction and
liquid lines
Answer:- d) Long lengths of suction and
liquid lines
30. The lubricating oil used with
R134a is ..........
a) Mineral Oil
b) Polyol Ester
c) Polyglycol
d) None of these
Answer:- b) Polyol Ester
31. PUF stands ior ...........
a) Poly user foam
b) Poly urea foam
c) Polyurethane foam
d) Polyurea urethane foam
Answer:- c) Polyurethane foam
32. Refrigerant R134a..........
a) Is Non flammable
b) is Flammable
c) Has Low GWP
d) Low ODP
Answer:- a) Is Non flammable
33. In a split AC the indoor
unit comprises of .......
a) Evaporator and blower
b) Evaporator coil, blower and
capillary tube
c) Evaporator coil, blower and motor,
air filter, control panel, supply and
return air grills
d) Evaporator coil, air filter, control
panel, supply and return air grills,
capillary tube
Answer:- c) Evaporator coil, blower and motor,
air filter, control panel, supply and
return air grills
34. Hissing or gurgling noise is
produced from at the exit of-
a) Evaporator
b) Compressor
c) Capillary tube
d) Condenser
Answer:- c) Capillary tube
35. The compressor of the car
Air-conditioning system gets
the drive from ............
a) Solar panels
b) Car battery
c) Generator of car
d) l.C. engine shaft
Answer:- d) l.C. engine shaft
36. The condenser of a car AC is .......
a) Water cooled
b) Air cooled
c) Evaporative type
d) None of these
Answer:- b) Air cooled
37. The drier filter of a window
AC is installed in ........
a) Suction line
b) Discharge line
c) Liquid line
d) Expansion
Answer:- c) Liquid line
38. The heal rejection capacity
of the condenser should be .........
a) Same as that of cooling capacity
b) Higher than cooling capacity
c) Lower than cooling capacity
d) Same that of compressor cooling
capacity
Answer:- b) Higher than cooling capacity
39. The upcoming alternative
refrigerant to be used in car air-
conditioning system is...........
a) R134a
a) R134a
b) RI234yf
c) R1234ze
d) R764
Answer:- b) RI234yf
40. The pressure testing of the
following equipment in the
plant is not necessary ............
a) Compressor
b) Evaporator
c) Condenser
d) None of these
Answer:- a) Compressor
41. The azeotropic refrigerant is ......
at R407C
b) R410A
c) R7I7
d) R502
Answer:- d) R502
42. The refrigerant leaves the
condenser as ............
a) High pressure saturated liquid
b) Low pressure saturated liquid
c) High pressure high temperature
saturated liquid
d) Low pressure high temperature
saturated liquid
Answer:- c) High pressure high temperature
saturated liquid
43. The thickness of fins used on
condenser coil of a window AC
is about ..........
a) 0.5 cm
a) 0.5 cm
b) 0.2 nun
c) 0.2 cm
d) 0.5
Answer:- b) 0.2 nun
44. A loss in vacuum after 24 hours
in standing vacuum test indicates
a) The presence of moisture
a) The presence of moisture
b) Leak in the system
c) Both (a) & (b)
d) None of these
Answer:- c) Both (a) & (b)
45.High pressure cut out is used
with......
a) Condenser
b) Evaporator
c) Compressor
d) Expansion valve
Answer:- c) Compressor
46. The lowest temperature with
liquid refrigerant in a vapour
compression refrigeration
system occurs after -
system occurs after -
a) Compression
b) Condensation
c) Evaporation
d) Expansion
Answer:- d) Expansion
47. A thermostatic expansion
valve is used with
a) Window air-conditioner
b) Split Air-conditioner
C) Central Air-conditioning plant
d) None of these
Answer:- C) Central Air-conditioning plant
48. The capacity of a refrigeration
plant is measured in .........
a) Litres
a) Litres
b) Metric
c) TR
d) Tonnes
Answer:- c) TR
49. This is a pari of Vapour compression
system ......
a) Absorber
b) Pump
c) Compressor
d) Turbine
Answer:- c) Compressor
50. Undercharging a system ........
a) Increases COP
b) Reduces COP
C) COP remains constant
d) None ol these
Answer:- b) Reduces COP
