Objective Questions Refrigeration MCQs

1. A refrigeration compressor were short cycling on the low pressure cut out switch the possible cause be
a] system is overcharged with refrigerant
b] suction valves were leaking slightly
c] the system was low on refrigerant
d] relief valves are leaking slightly

2. The refrigeration compressor in a water cooled refrigeration system is short cycling on the high pressure cutout switch. One reason for this could be the

a] system is low on refrigerant
b] high pressure cut out is improperly adjusted
c] discharge valves are leaking slightly
d] discharge valves are leaking excessively

3. Air trapped in a refrigeration system using a water-cooled condenser is usually indicated by
a] unusually high head pressure when compared to the existing temperature of the liquid refrigerant
b] higher than normal liquid level in the receiver
c] unusually lower than normal discharge pressure when compared to the existing temperature of the liquid refrigerant
d] higher than normal liquid refrigerant temperature

4. Refrigerant is normally subcooled in a refrigeration or air conditioning system condenser to
a] maintain adequate coil back pressure
b] prohibit flashing in liquid line
c] reduce refrigeration volume in the system
d] reduce compressor discharge line loading

5. Subcooling is a method of reducing the temperature of the liquid refrigerant below its
a] freezing point
b] flash point
c] condensing temperature
d] compression temperature

6. Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system as a

a] liquid
b] dry saturated gas
c] wet saturated gas
d] superheated vapour

7. Refrigerant enters the condenser as a
a] high pressure liquid
b] low pressure vapor
c] high pressure vapor
d] low pressure liquid

8. In a refrigeration system, the heat normally producing the flash gas at the thermostatic expansion valve, is obtained from
a] the hot gas bypass connection at the threeway valve
b] the portion of liquid refrigerant which does not flash
c] exposure to the high ambient temperature within the coil
d] exposure to the high ambient temperature of the cooled space

9. The effect of high vapor superheat in a refrigeration system, is a/an

a] increased capacity of the compressor
b] more efficient operation of the thermal expansion valve
c] decreased capacity of the compressor
d] loss of receiver capacity

10. In which of the listed refrigeration system components does super heating of the refrigerant take place?
a] expansion valve
b] evaporator
c] drier
d] receiver

11. The low pressure side of a refrigeration system is considered to exist from the
a] expansion valve to the compressor
b] receiver to the expansion coil
c] expansion valve to the evaporator
d] condenser to the expansion valve

12. The temperature of a refrigerant gas is the highest at
a] at the compressor discharge
b] at the compressor suction
c] in the expansion valve
d] in the receiver

13. Which of the listed refrigeration system components keeps the refrigerant circulating through the system?
a] expansion valve
b] condenser
c] evaporator
d] compressor

14. Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause

a] compressor damage from improper lubrication
b] refrigerant absorption by the lubricant
c] increased viscosity in the lubricant
d] carbon deposit in the compressor suction valves

15. When refrigerant leaves the receiver, it flows next on to the
a] evaporator coils
b] liquid strainer
c] compressor
d] condenser

16. An increase in the heat load to a refrigeration system will cause 

a] the suction pressure to decrease  
b] the suction temperature to increase 
c] increased ice formation on the evaporator coil 
d] excessive short cycling of the compressor

17. Which of the following terms would best describe the temperature at which a liquid boils at a given pressure? 

a] degree of saturation
b] saturation temperature
c] superheated temperature
d] degree of superheat

18. A refrigerant with oil in solution has a
a] higher boiling temperature for a given pressure than does a pure refrigerant 
b] lower boiling temperature for a given pressure than does a pure refrigerant
c] boiling pressure equal to that of a pure refrigerant at a given pressure
d] boiling point will not be affected by entrained oil

19. In a compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease in the
a] evaporator
b] compressor
c] expansion valve
d] condenser

20. If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be
a] a shortage of compressor oil
b] warm food in the refrigerator
c] excessive condenser cooling water
d] a shortage of refrigerant


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