Sub-cooling is a method of reducing the temperature of the liquid refrigerant below its ______.A.freezing pointB.floc point(浊点)C.condensing temperatureD.compression temperature
Sub-cooling is a method of reducing the temperature of the liquid refrigerant below its ______.
A.freezing point
B.floc point(浊点)
C.condensing temperature
D.compression temperature
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Which method shown below is acceptable for reducing cost or shortening the schedule?A."Crashing"B.Changing scope.C.Performing activities in parallel rather than in series.D.All of the above.E.A and C only.
The temperature of the refrigerant in the evaporator coil depends mostly upon the ___.A.refrigerant pressure in the evaporatorB.cooling water temperature to the condenserC.heat load in the refrigerator compartmentD.solenoid valve in the liquid line
If the superheat value of a thermostatic expansion valve is set too low, the _.A.the suction line will be abnormally cold and liquid may slug back to the compressorB.the suction line will be hot due to a reduced amount of refrigerant returning to the compressorC.the temperature of the refrigerant within the condenser will remain the sameD.the temperature of the refrigerant passing through the sub-cooler will decrease
Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of ______.A.refrigerant bubbles in the lube oilB.refrigerant reducing the lube oil viscosityC.oxidation(氧化) of the lube oil from overheatingD.reducing the floc or cloud point of the oil
Reid vapor pressure is ______．A.exerted by liquid cargo on the sides of a tankB.exerted by liquid cargo on a cargo hose bodyC.the lowest temperature and pressure that will cause a flammable liquid to give off vaporsD.a measurement of the amount of flammable vapors given off by a liquid at a certain temperature
单选题When the temperature of the refrigerant flowing out from the condenser is below the condensing temperature, it is said to be （）.AdryBwetCsuper-cooledDsuperheated
单选题Reid vapor pressure is（）.Aexerted by liquid cargo on the sides of a tankBexerted by liquid cargo on a cargo hose bodyCthe lowest temperature and pressure that will cause a flammable liquid to give off vaporsDa measurement of the amount of flammable vapors given off by a liquid at a certain temperature
单选题A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of（）.Aa shortage of refrigerant in the systemBair in the systemCan accumulation of liquid refrigerant in the crankcaseDa shortage of oil in the crankcase
单选题（） is the temperature at which a liquid fuel gives off sufficient vapor to form an ignitable mixture near its surface.ASetting pointBDew pointCFlash pointDLean point
单选题An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.Arestriction in refrigerant pipingBair and non-condensable gases in the condenserCwater in the refrigerantDflooding back of liquid refrigerant from the evaporator
单选题If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is （）.Atoo much refrigerant in the systemBoil entrained in the refrigerantCless than a full charge of refrigerant in the systemDice crystals forming in the refrigerant
单选题A pressure drop through the refrigerant liquid line may cause （）.Asolenoid valve to seizeBcompressor to huntCformation of flash gas in the liquid lineDexpansion valve to freeze open
单选题The temperature （） a liquid changes its state from liquid to gas depends upon the liquid itself and upon the pressure （） it is subjected in the containing vessel.Aat which/to whichBfrom which/at whichCto which/from whichDin which/on which
单选题The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of （）.AfusionBvaporizationCcondensationDsublimation
单选题Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）AThe liquid receiver functions to collect and remove non-condensable gasesBA thermostatic expansion valve is used to control refrigerated space temperatureCRefrigerant temperature in an evaporator is directly related to refrigerant pressureDDehydrators must be used continuously in a refrigeration system
单选题The flash point of a liquid refers to the temperature （）Aat which a liquid will give off inflammable vaporsBat which a liquid will burn steadilyCat which a liquid will explodeDthat a liquid must reach before it will flow readily
单选题In a compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease in the（）.AevaporatorBcompressorCexpansion valveDcondenser
单选题The temperature of the refrigerant in the evaporator coil depends mostly upon the （）.Arefrigerant pressure in the evaporatorBcooling water temperature to the condenserCheat load in the refrigerator compartmentDsolenoid valve in the liquid line
单选题In terms of pressure and temperature in the refrigerant in the compressor, what happens to the primary?（）Aits pressure and temperature are both loweredBits pressure and temperature are both raisedCits pressure is lowered and its temperature is raisedDits pressure is raised and its temperature is lowered
单选题“Flooding back” is a condition where the liquid refrigerant （）.Avaporizes in the condenserBreaches the compressor through the suction lineCflashes in the liquid lineDcondenses in the receiver
单选题Which of the listed statements is a characteristic of the liquid charged power element used with thermostatic expansion valves?（）AAt the designed operating temperature, the liquid refrigerant charge has changed to a vaporBThe liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivityCThe sensing bulb is empty of liquid refrigerant charge at the designed operating temperatureDThe sensing bulb is never emptied of liquid refrigerant under normal operating conditions
单选题The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.Aincrease the refrigerating effect, by decreasing the amount of flash gasBallow the refrigerant to enter the throttling device in a saturated conditionCincrease the refrigerating effect by increasing the amount of flash gasDminimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
单选题Sub-cooling is a method of reducing the temperature of the liquid refrigerant below its （）.Afreezing pointBfloc pointCcondensing temperatureDcompression temperature
单选题The best method of extinguishing a class A fire is to （）.Aremove oxygen from the areaBsmother fire with foamCsmother fire with CO2Dcool fuel below ignition temperature
单选题If the compressor-discharge temperature is higher than the receiver temperature（）Aincrease the amount of cooling water to the condenserBdecrease the amount of cooling water to the condenserCadd more refrigerant to the systemDremove some of the refrigerant from the system
单选题A sight glass is installed in the liquid line to indicate the condition of the refrigerant charge and may also indicate the （）.Acondition of the expansion valveBmoisture in the systemCcondition of the compressor suction valvesDcondenser temperature
单选题The lowest temperature at which a liquid gives off enough vapor to ignite in the presence of an ignition source is called its （）.Aboiling pointBflash pointCviscosity pointDtoxic point