Refrigeration and Air Conditioning MCQs

Free 94+ Refrigeration and Air Conditioning MCQs for PPSC, FPSC, NTS, and Pakistan government job tests. Practise below with answers and explanations.

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94 questions in this list. Select an option to practice, or open a question for the full page with explanation.

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Refrigeration and Air Conditioning

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1.In refrigeration cabinets, when there is a significant difference in temperature and vapor pressure between the inside of the cabinet and the surrounding atmosphere, what measure should be taken?

Use a larger cabinet sizeChoose a smaller cabinet designEnsure the vapor seal is completely airtightSelect a refrigerant with a lower evaporation pointOpt for a refrigerant that has a higher boiling temperature

2.What is the benefit of using dry compression in a system?

It allows the system to operate at increased speedsIt ensures full evaporation within the evaporatorIt achieves high volumetric and mechanical efficiencyAll of the above advantages applyNone of these benefits are correct

3.How does the diameter of the suction pipe in a refrigeration compressor compare to that of the discharge pipe?

largernarrowerthe same sizevaries based on capacitycannot be determined

4.How does undercooling affect the coefficient of performance (COP) in a refrigeration cycle?

It improves the COPIt reduces the coefficient of friction (COF)The COP stays the sameCOP is influenced by other variablesThe impact is unpredictable

5.The coefficient of performance (COP) is defined as the ratio of the refrigeration effect to which of the following?

energy used during compressionmechanical work input to the compressorrise in enthalpy within the compressorall the above factors combinednone of these options

6.On a pressure-enthalpy diagram, vertical lines represent which constant property?

Lines of constant pressureLines of constant temperatureLines of constant total heatLines of constant entropyLines of constant volume

7.What is the typical horsepower range per ton of refrigeration used to rate refrigeration systems, excluding CO2 systems?

Between 0.1 and 0.5 horsepower per ton of refrigerationFrom 0.5 up to 0.8 horsepower per ton of refrigerationApproximately 1 to 2 horsepower per ton of refrigerationRanging from 2 to 5 horsepower per ton of refrigerationBetween 5 and 10 horsepower per ton of refrigeration

8.In an ammonia absorption plant, which equipment specifically requires cooling water?

CondenserEvaporatorAbsorberBoth condenser and absorberCondenser, absorber, and separator (rectifier)

9.How does the coefficient of performance (COP) of a refrigeration cycle change when the condenser temperature is reduced while maintaining a constant evaporator temperature?

It increasesIt decreasesIt may either increase or decrease depending on the refrigerant typeIt stays the sameIt cannot be predicted

10.When does the heat of solution develop in an ammonia absorption system?

Ammonia vapor dissolves into the solutionAmmonia vapor is expelled from the solutionLithium bromide combines with ammoniaA dilute solution blends with a concentrated solutionLithium bromide is removed from the solution

11.How does the coefficient of performance (COP) of a vapor compression refrigeration system compare to that of a vapor absorption system?

HigherLowerEqualVaries with the size of the systemCannot be determined

12.How does a variation in evaporator temperature, relative to a change in condenser temperature, affect the coefficient of performance (C.O.P) in a refrigeration cycle?

It impacts the C.O.P to a greater extentIt affects the C.O.P to a lesser degreeIt influences the C.O.P equallyIts effect on C.O.P is unpredictableNone of the above

13.Among the refrigerants listed below, which one has the lowest freezing point?

Freon-12Ammonia (NH3)Carbon Dioxide (CO2)Freon-22Sulfur Dioxide (SO2)

14.How does the refrigeration capacity of a dry evaporator compare to that of a flooded evaporator in an identical system?

EquivalentHigherLowerVaries based on environmental factorsCannot be determined

15.What are the effects of decreasing the suction pressure in a refrigeration cycle?

It causes the evaporation temperature to drop.It raises the power consumption per ton of refrigeration.It decreases the compressor's capacity since the vapor becomes lighter.It lowers the weight of the vapor displaced by the piston.All of the above.

16.Which refrigeration system is commonly used in the majority of household refrigerators?

Vapor compression systemVapor absorption systemCarnot refrigeration cycleElectrolux refrigeration systemDual refrigeration cycle

17.How does the coefficient of performance (COP) of a refrigeration cycle change when the evaporator temperature rises while the condenser temperature remains fixed?

It increasesIt decreasesIt stays the sameIt varies depending on the refrigerant typeIt cannot be predicted