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In the refrigeration compressor the temperature of the vapor is （） by compression.
A . raised
B . risen
C . reduced
D . maintained constant
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Sweating of the refrigeration system compressor crankcase is caused by （）.
A . too much superheat
B . insufficient superheat
C . suction pressure too low
D . excessive refrigerant returning to the compressor
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If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
A . the relief valve should open before the high pressure cutout
B . the relief valve should open and allow the excess refrigerant to flow to the receiver
C . the high pressure cutout switch should operate before the relief valve opens
D . you should close in on the suction valve
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In practice, the refrigerant flow after the evaporator is designed to ensure that the vapor leaving the evaporator is slightly （）.
A . saturated
B . super-cooled
C . wet
D . superheated
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As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into （）.
A . liquid
B . oily mixture
C . emulsion
D . vapor
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In the refrigeration system, a shortage of refrigerant is indicated by （）.
A . the compressor short cycling on high pressure cut out switch
B . high suction pressure
C . high head pressure
D . bubbles in the sight gla
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The color of the flame on a halide torch without any refrigerant present is （）.
A . blue
B . green
C . orange
D . purple
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Which of the listed statements is correct concerning refrigeration systems?（）
A . Dehydrators must be used continuously in a refrigeration system
B . A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hours
C . A thermostatic expansion valve is used to control refrigerated space temperature
D . The liquid receiver functions to collect and remove non- condensable gase
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The refrigeration system low pressure cutout switch is actuated by （）.
A . an electric system manager
B . a sensing bulb at the tail coil of the evaporator
C . pressure changes in the suction line
D . failure of the king solenoid valve
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If the refrigeration compressor crankcase is sweating, the cause may be due to （）.
A . a shortage of refrigerant
B . the compressor running continuously
C . liquid refrigerant returning to the compressor
D . the compressor short cycling on the high pressure cutout
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In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.
A . compressor；condenser
B . condenser；evaporator
C . throttle valve；evaporator
D . evaporator；condenser
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The temperature of a refrigerant gas is the highest （）.
A . at the compressor discharge
B . at the compressor suction
C . in the expansion valve
D . in the receiver
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The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the （）.
A . condenser
B . vapor generator
C . accumulator
D . evaporator
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“Flooding back” is a condition where the liquid refrigerant （）.
A . vaporizes in the condenser
B . reaches the compressor through the suction line
C . flashes in the liquid line
D . condenses in the receiver
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If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
A . refrigerant overcharge
B . overfeeding by the expansion valve
C . a restricted suction strainer
D . due to short cycling of the compressor
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If a refrigeration compressor is running continuously without lowering temperature as normal in the refrigerator, the trouble may be （）.
A . excessive condenser cooling water
B . warm food in the refrigerator
C . a shortage of refrigerant
D . s shortage of compressor oil
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The latent heat of evaporation is dissipated in the （） in a compression refrigeration system.
A . evaporator
B . condenser
C . expansion valve
D . compressor
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The function of （） in a refrigeration plant using Freon is to move moisture from all refrigeration system.
A . filter
B . filter drier
C . heat exchanger
D . air cooler
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The purpose of the refrigeration system low pressure cutout switch is to （）
A . protect the compressor from liquid flood back
B . protect the compressor from low discharge pressure
C . start and stop the compressor upon system demand
D . start the compressor after a drop in the evaporator pressure
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When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.
A . always be wide open when the compressor restarts
B . continue to operate as if the system were in operation
C . remain open until evaporator pressure equalizes, then close until the compressor restarts
D . always be completely closed until the compressor restart
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When the temperature of the refrigerant flowing out from the condenser is below the condensing temperature, it is said to be （）.
A . dry
B . wet
C . super-cooled
D . superheated
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原文:Even when we turn off the beside lamp and are fast asleep, electricity is working for us, driving our refrigerators, heating our water, or keeping our rooms air-conditioned.译文:即使我们关掉床头灯睡觉,电仍然在为我们工作,如启动电冰箱,把水加热,或让室内空调持续开着。
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The milk is ______ the refrigerator.
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When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will .
A.always be wide open when the compressor restarts
B.continue to operate as if the system were in operation
C.remain open until evaporator pressure equalizes, then close until the compressor restarts
D.always be completely closed until the compressor restarts
