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
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