Refrigeration and Air-Conditioning

ME6I

22660

Multiple Choice Questions (MCQs)

1   The heat removing capacity of one ton of refrigeration is equal to
    (A)   21 kJ/min
    (B)   210 kJ/min
    (C)   3.5 kJ/min
    (D)   350 kJ/min
[showhide type=”button7c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
2   One ton of refrigeration means that
    (A)   One ton is the total mass of the machine
    (B)   One ton of refrigerant is used
    (C)   One ton of water is converted
    (D)   One ton of ice when melts from and at 0⁰C in 24hours, the refrigeration effect produced is equivalent to 210 kJ/min
[showhide type=”button7c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
3   The coefficient of performance of heat pump is always
    (A)   Equal to one
    (B)   Less than one
    (C)   Greater than one
    (D)   Equal to half of refrigerator
[showhide type=”button7c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
4   If the condenser and evaporator temperatures are 312K and 273K respectively, then COP of reversed Carnot cycle is
    (A)   5
    (B)   7
    (C)   9
    (D)   10
[showhide type=”button7c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
5   Air refrigeration cycle is used in
    (A)   Commercial refrigerators
    (B)   Domestic refrigerators
    (C)   Air conditioning
    (D)   Passenger aircraft
[showhide type=”button7c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
6   In refrigerating machine, heat rejected is —– heat absorbed.
    (A)   Equal to
    (B)   Less than
    (C)   Greater than
    (D)   Less than or equal to
[showhide type=”button7c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
7   Air refrigerator works on
    (A)   Carnot cycle
    (B)   Reversed Carnot cycle
    (C)   Vapor Compression cycle
    (D)   Bell Coleman cycle
[showhide type=”button7c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
8   For a refrigerating system that works on Bell-Coleman cycle, which one of the following is not a process of the cycle?
    (A)   Isentropic compression process
    (B)   Constant pressure cooling process
    (C)   Isothermal expansion process
    (D)   Constant pressure expansion process
[showhide type=”button7c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
9   Reverse Carnot cycle has the following two combination of processes
    (A)   Isothermal-isobaric
    (B)   Isothermal-Isentropic
    (C)   Isobaric-Isentropic
    (D)   Isentropic-Isochoric
[showhide type=”button7c9″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
10   Bell Coleman cycle has the following two combination of processes
    (A)   Isothermal-isobaric
    (B)   Isothermal-Isentropic
    (C)   Isobaric-Isentropic
    (D)   Isentropic-Isochoric
[showhide type=”button7c10″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
11   In a refrigeration system, the expansion device is connected between the
    (A)   Condenser and receiver
    (B)   Compressor and condenser
    (C)   Receiver and evaporator
    (D)   Evaporator and compressor
[showhide type=”button7c11″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
12   Select most widely used refrigeration cycle in use today
    (A)   Reversed Carnot cycle
    (B)   Bell Coleman cycle
    (C)   Vapor compression cycle
    (D)   Vapor absorption cycle
[showhide type=”button7c12″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
13   Select sources of heating the air craft
    (A)   Solar radiation
    (B)   Occupants and equipment
    (C)   Skin friction due to fast movement
    (D)   Represent all the given options
[showhide type=”button7c13″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
14   The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.
    (A)   Same
    (B)   Higher
    (C)   Lower
    (D)   None of these
[showhide type=”button7c14″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
15   A refrigeration system
    (A)   Removes heat from a low temperature body and delivers it to a high temperature body
    (B)   Removes heat from a high temperature body and delivers it to a low temperature body
    (C)   Rejects energy to a low temperature body
    (D)   None of the above
[showhide type=”button7c15″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
16   In vapor compression cycle, heat is rejected by refrigerant in a
    (A)   compressor
    (B)   condenser
    (C)   expansion valve
    (D)   evaporator
[showhide type=”button7c16″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
17   The higher temperature in vapour compression cycle occurs at
    (A)   Compressor discharge
    (B)   Receiver
    (C)   Evaporator
    (D)   After expansion
[showhide type=”button7c17″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
18   Montreal protocol is related to the
    (A)   Ozone layer depletion
    (B)   Global warming
    (C)   Sustainable development
    (D)   Food security
[showhide type=”button7c18″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
19   Which of the following are ozone depleting substances?
    (A)   Chlorofluorocarbons (CFCs)
    (B)   Hydrofluorocarbons (HFCs)
    (C)   Hydrochlorofluorocarbons (HCFCs)
    (D)   Both CFCs and HCFCS
[showhide type=”button7c19″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
20   What is the value of C.O.P. of VCR cycle?
    (A)   h1 – h2 / h1 – h4
    (B)   h1 – h4 / h2 – h1
    (C)   h2 – h1 / h4 – h1
    (D)   h1 – h3 / h2 – h1
[showhide type=”button7c20″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
21   When refrigerants take a direct part in the refrigeration system, then these types of refrigerants are called?
    (A)   Primary Refrigerant
    (B)   Secondary Refrigerant
    (C)   Mixed Refrigerant
    (D)   None of the above
[showhide type=”button7c21″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
22   Refrigerant is
    (A)   Heat carrying medium
    (B)   Heat storing medium
    (C)   Heat dissipating medium
    (D)   Represent all the given options
[showhide type=”button7c22″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
23   The COP of a Carnot refrigerating machine is 7.8. What will be the COP of heat pump?
    (A)   9.8
    (B)   6.8
    (C)   7.8
    (D)   8.8
[showhide type=”button7c23″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
24   The relative coefficient of performance (C.O.P.) is equal to…….
    (A)   Theoretical C.O.P./Actual C.O.P.
    (B)   Actual C.O.P./Theoretical C.O.P.
    (C)   Theoretical C.O.P. x Actual C.O.P.
    (D)   Theoretical C.O.P. + Actual C.O.P.
[showhide type=”button7c24″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
25   In refrigeration cycle, the flow of refrigerant is controlled by ….
    (A)   Condenser
    (B)   Evaporator
    (C)   Expansion Valve
    (D)   Compressor
[showhide type=”button7c25″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
26   Identify refrigeration cycle as given below sketch
    (A)   Vapour compression cycle
    (B)   Reverse Carnot cycle
    (C)   Bell Coleman cycle
    (D)   Air Refrigeration cycle
[showhide type=”button7c26″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
27   Ideally two-phase mixture refrigerant enters into………
    (A)   Compressor
    (B)   Evaporator
    (C)   Condenser
    (D)   Expansion valve
[showhide type=”button7c27″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
28   Refrigeration cycle work on
    (A)   First Law of Thermodynamic
    (B)   Second Law of Thermodynamic
    (C)   Third Law of Thermodynamic
    (D)   None of the above
[showhide type=”button7c28″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
29   In refrigerating machine, heat rejected is……….heat absorbed.
    (A)   Equal to
    (B)   Less than
    (C)   Greater than
    (D)   Less than or equal to
[showhide type=”button7c29″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
30   Select the odd one out with respect to Bell Coleman cycle
    (A)   Compressor
    (B)   Condenser
    (C)   Expander
    (D)   Refrigerator
[showhide type=”button7c30″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
31   In ideal VCR cycle, phase of refrigerant at the exit of compressor will be
    (A)   Dry
    (B)   Wet
    (C)   Superheated
    (D)   Subcooled liquid
[showhide type=”button8c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
32   Subcooling of vapor compression cycle increases
    (A)   Life of compressor
    (B)   COP of cycle
    (C)   Life of compressor as well as COP of cycle
    (D)   Work requirement of compressor
[showhide type=”button8c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
33   Select the cycle shown in figure

    (A)   Reversed Carnot cycle
    (B)   Vapor absorption cycle
    (C)   Vapor compression cycle
    (D)   Bell Coleman cycle
[showhide type=”button8c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
34   Superheating is the process of heating the refrigerant above its normal boiling point under pressure in VCR cycle
    (A)   before compression
    (B)   after compression
    (C)   before expansion
    (D)   after expansion
[showhide type=”button8c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
35   In general refrigerant expression: R(m-1) (n+1) q, “n” is represented by
    (A)   hydrogen atom
    (B)   carbon atom
    (C)   fluorine atom
    (D)   chlorine atom
[showhide type=”button8c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
36   Select the most suitable option from the following with respect to moisture present in the VCR cycle
    (A)   Expansion valve chock up
    (B)   Compressor will run dry
    (C)   Compressor will prone to burst
    (D)   Represent all the given options
[showhide type=”button8c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
37   Sulphur candle can be used to detect which type of refrigerant
    (A)   CO2
    (B)   Ammonia
    (C)   R12
    (D)   SO2
[showhide type=”button8c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
38   Select the correct operations from the following before charging the refrigerant. 1. Evacuate the system 2. Connect a refrigerant cylinder to charging manifold with hoses. 3. Charge with only correct refrigerant. 4. Service connection lines must be clean and free of air. Clean lines by flushing refrigerant through hoses before charging
    (A)   only 1 & 3 are correct
    (B)   only 2 & 4 are correct
    (C)   Only 3 & 4 are correct
    (D)   All are correct
[showhide type=”button8c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
39   Dichlorodifluoromethane is
    (A)   R11
    (B)   R12
    (C)   R13
    (D)   R14
[showhide type=”button8c9″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
40   Which component is absent in Vapor absorption cycle?
    (A)   Condenser
    (B)   Evaporator
    (C)   Compressor
    (D)   Expansion valve
[showhide type=”button8c10″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
41   If pressure ratio is 5 and γ=1.4, then find COP of Bell Coleman refrigerator
    (A)   1.7
    (B)   3.1
    (C)   5.1
    (D)   4.2
[showhide type=”button8c11″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
42   Dehumidification of air is normally done by _______
    (A)   Heating
    (B)   Cooling
    (C)   Superheating
    (D)   Injecting water spray
[showhide type=”button8c12″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
43   Dew point temperature lines on the psychrometric chart are
    (A)   Horizontal
    (B)   Vertical
    (C)   Curved
    (D)   Straight inclined slopping downward to the right
[showhide type=”button8c13″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
44   The wet bulb temperature at 100% relative humidity as compared to dew point temperature is
    (A)   Same
    (B)   Lower
    (C)   Higher
    (D)   unpredictable
[showhide type=”button8c14″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
45   For sensible heating the air is passed over heating coils which may be
    (A)   Electric resistance coils
    (B)   Hot water passed through coils
    (C)   Steam passed through coils
    (D)   All of the above
[showhide type=”button8c15″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
46   The process used for summer air conditioning for hot and humid conditions are
    (A)   Heating and humidification
    (B)   Cooling and humidification
    (C)   Heating and dehumidification
    (D)   Cooling and dehumidification
[showhide type=”button8c16″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
47   During sensible cooling of air, relative humidity ____
    (A)   Increases
    (B)   Decrease
    (C)   Remains same
    (D)   None of the above
[showhide type=”button8c17″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
48   When air is passed over silica gel or activated alumina, the air gets ____________
    (A)   Heated and humidified
    (B)   Cooled and humidified
    (C)   Heated and dehumidified
    (D)   Cooled and dehumidified
[showhide type=”button8c18″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
49   Process of adding heat to moist air at the same specific humidity is known as ________
    (A)   Sensible heating
    (B)   Humidification
    (C)   Dehumidification
    (D)   Sensible cooling
[showhide type=”button8c19″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
50   Ratio of mass of water vapor associated with unit mass of dry air to the mass of water vapor associated with unit mass of saturated air at the same temperature is known as _____
    (A)   Relative humidity
    (B)   Absolute humidity
    (C)   Specific humidity
    (D)   Degree of saturation
[showhide type=”button8c20″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
51   Dry bulb temperature, wet bulb temperature and dew point are same for_________
    (A)   Dry air
    (B)   Saturated air
    (C)   Unsaturated air
    (D)   Moist air
[showhide type=”button8c21″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]
52   Which type of evaporator is shown in figure
    (A)   Finned type
    (B)   Bare tube type
    (C)   Shell and tube type
    (D)   plate type
[showhide type=”button8c22″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
53   Which expansion device used in domestic refrigerator?
    (A)   Electrically operated throttling valve
    (B)   Manually operated valve
    (C)   Thermostatic valve
    (D)   Capillary tube
[showhide type=”button8c23″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
54   Thermostatic expansion valve responds to
    (A)   Suction superheat
    (B)   Liquid subcooling
    (C)   Suction pressure
    (D)   Discharge pressure
[showhide type=”button8c24″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
55   Automatic expansion valve responds to
    (A)   Suction superheat
    (B)   Liquid subcooling
    (C)   Suction pressure
    (D)   Discharge pressure
[showhide type=”button8c25″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]
56   Which expansion device doesn’t adjust itself to seasonal variation?
    (A)   Capillary tube
    (B)   Thermostatic expansion valve
    (C)   Automatic expansion valve
    (D)   Float valve
[showhide type=”button8c26″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
57   “Heart” of any refrigeration and air conditioning system is
    (A)   Compressor
    (B)   Condenser
    (C)   Expansion valve
    (D)   Evaporator
[showhide type=”button8c27″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
58   To cut off and on the refrigerant in the system —– device is used.
    (A)   Solenoid valve
    (B)   Relay
    (C)   Drier
    (D)   Thermostatic switch
[showhide type=”button8c28″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
59   —– are used for cooling secondary refrigerant.
    (A)   Chillers
    (B)   Evaporators
    (C)   Condensers
    (D)   anyone can be used
[showhide type=”button8c29″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
60   Pressure in the capillary tube decreases due to following: 1. Frictional resistance offered by tube wall 2. Acceleration of refrigerant in the tube 3. Heat transfer from tube wall 4. Decrease in potential energy
    (A)   1 & 2 statements are correct
    (B)   3 & 4 statements are correct
    (C)   1, 2 & 4 statements are correct
    (D)   All statements are correct
[showhide type=”button8c30″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
61   Which type of condenser is shown in figure

    (A)   Evaporative type
    (B)   Forced convection type
    (C)   Natural convection type
    (D)   Water cooled type
[showhide type=”button9c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
62   The rate at which body produces heat is
    (A)   metabolic rate
    (B)   Heat storage rate
    (C)   work done by body
    (D)   rate of convection
[showhide type=”button9c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
63   Heat transfer by —– is always positive in thermal exchange of the body with environment.
    (A)   evaporation
    (B)   convection
    (C)   radiation
    (D)   heat storage in the body
[showhide type=”button9c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
64   Usual body temperature for a normal person is (in °C)
    (A)   37
    (B)   43
    (C)   40
    (D)   34
[showhide type=”button9c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
65   Heat exchange between person and its environment is expressed by —–relation. Qm: metabolic rate, W: work done by body, Qe: heat loss by evaporation, Qc: heat loss by convection, Qr: heat loss by radiation, Qs: rate of heat storage
    (A)   Qm – W = Qe ± Qr ± Qc ± Qs
    (B)   Qm – W = ± Qe ± Qr ± Qc ± Qs
    (C)   Qm – W = Qe ± Qr ± Qc – Qs
    (D)   Qm – W = Qe ± Qr ± Qc + Qs
[showhide type=”button9c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
66   Which of the following is not latent heat load?
    (A)   moisture from occupants
    (B)   moisture from cooking foods
    (C)   infiltrated moisture from outside air
    (D)   heat conducted through walls, floors and ceilings
[showhide type=”button9c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
67   Condition of a person which expresses satisfaction with the thermal environment is called
    (A)   Human comfort
    (B)   Human pleasure
    (C)   Human expectation
    (D)   Human contentment
[showhide type=”button9c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]
68   Sensible heat loads include
    (A)   heat transmitted through walls, ceilings, floors
    (B)   heat transfer from light, motors machinery
    (C)   heat carried out by outside air through cracks
    (D)   Represent all the given option
[showhide type=”button9c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]
69   A human body feels comfortable when heat produced by the metabolism of human body is equal to the
    (A)   Heat dissipated to the surroundings
    (B)   Heat stored in the human body
    (C)   Difference of (a) and (b)
    (D)   Sum of (a) and (b)
[showhide type=”button9c9″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

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