单选题When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.Aalways be wide open when the compressor restartsBcontinue to operate as if the system were in operationCremain open until evaporator pressure equalizes, then close until the compressor restartsDalways be completely closed until the compressor restarts
单选题
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
参考解析
解析：
暂无解析
相关考题：
If the refrigeration compressor crankcase is sweating, the cause may be due toA.a shortage of refrigerantB.the compressor running continuouslyC.liquid refrigerant returning to the compressorD.the compressor short cycling on the high pressure cutout
When adding oil to a refrigeration system, precautions must be taken to ensure thatA.the compressor suction pressure is not too highB.all air is purged from the pump and charging fittingsC.the high pressure cutout switch is held open to prevent accidental startingD.the condenser is completely shutdown first
Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur when the compressorA.has run continuously for a long periodB.suction pressure is below normalC.oil level is below normalD.starts after a long idle period
Sweating of the refrigeration system compressor crankcase is caused by_______ .A.too much superheatB.insufficient superheatC.suction pressure too lowD.excessive refrigerant returning to the compressor
If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.A.an excess of liquid refrigerantB.the expansion valve overfeedingC.a fouled compressor suction strainerD.the compressor short cycling
单选题Low compressor head pressure in a refrigeration system can be caused by（）.Ainsufficient condenser cooling waterBexcessive condenser cooling waterCair in the refrigeration systemDexcessive refrigerant in the system
单选题In a direct expansion type multi-box refrigeration system, the compressor is set up to cycle on and off by the（）ApressurestatBhigh pressure cutoutCsolenoid valveDlow pressure cutout switch
单选题When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called （）.Aflooding backBsuperheatingCoverflowingDrecycling
单选题Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.Aoverheated compressor bearingsBexcess lube oil viscosityCcarbon deposits on the compressor piston ringsDwax crystals forming in the lubricant
单选题When adding oil to a refrigeration system, precautions must be taken to ensure that （）.Athe compressor suction pressure is not too highBall air is purged from the pump and charging fittingsCthe high pressure cutout switch is held open to prevent accidental startingDthe condenser is completely shutdown first
单选题If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be （）.Aa shortage of compressor oilBwarm food in the refrigeratorCexcessive condenser cooling waterDa shortage of refrigerant
单选题If the discharge valves on a refrigeration compressor are leaking badly, the compressor should （）.Arun continuouslyBnot startChave high discharge pressureDshort cycle on the high pressure switch
单选题（）are supplied by main switchboard directly.ASuez Canal searchlight, air compressor and air conditioning compressorBAir compressor, boiler blower and refrigeration plantCBoiler blower, Suez Canal searchlight and refrigeration plantDSuez canal searchlight, air compressor and boiler blower
单选题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.Aa shortage of refrigerantBthe compressor running continuouslyCliquid refrigerant returning to the compressorDthe compressor short cycling on the high pressure cutout
单选题A refrigeration unit will tend to short cycle when operating （）.Aunder heavy loadsBduring hot gas defrostCunder light loadsDduring starting conditions
单选题If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.Arefrigerant overchargeBoverfeeding by the expansion valveCa restricted suction strainerDdue to short cycling of the compressor
单选题If the capacity of the refrigeration compressor is too large, the saturation temperature will （）.AriseBfallCbe maintained constantDNone of the above
单选题In the refrigeration compressor the temperature of the vapor is （） by compression.AraisedBrisenCreducedDmaintained constant
单选题It should be ensured that only （） vapor is handled by the refrigeration compressor.AhumidityBdryCsteamDoil
单选题Which of the following may cause that the compressor cuts off on high pressure cutout in a refrigeration plant? （） (1) faulty condensing (2) too few refrigerant (3) high discharge pressureAany of (1) and (3)Bany of (1) and (2)Cany of (2) and (3)Dany of (1), (2) and (3)
单选题Diesel engine valve springs function to （）Ahold the valves openBkeep the valves off their seats until the exhaust stroke is completedCclose the valvesDopen inlet valves when the air injection cycle begins
单选题The purpose of the refrigeration system low pressure cutout switch is to （）Aprotect the compressor from liquid flood backBprotect the compressor from low discharge pressureCstart and stop the compressor upon system demandDstart the compressor after a drop in the evaporator pressure
单选题Sweating of the refrigeration system compressor crankcase is caused by （）.Atoo much superheatBinsufficient superheatCsuction pressure too lowDexcessive refrigerant returning to the compressor
单选题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.Aincrease the amount of cooling water to the condenserBdecrease the amount of cooling water to the condenserCadd more refrigerant to the systemDremove some refrigerant from the system
单选题Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur（） when the compressor.Ahas continuously for a long periodBsuction pressure is below normalCoil level is below normalDstarts after a long idle period
单选题Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?（）AThe condenser and the expansion valveBThe king valve and the solenoid valveCThe compressor and the expansion valveDThe condenser and the solenoid valve
单选题When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is a （）.Aloose expansion valve control bulbBlow differential setting on the H-PcutoutCblown fuse in the motor circuitDfaulty suction pressure regulator