2.3 船舶制冷和空调装置

2.3.1 制冷原理和制冷循环1734.The thermal expansion valve responds to the ______.amount of superheat in the vapor leaving the coilamount of superheat in the liquidtemperature in the evaporator coilspressure in the evaporator coils1742.A refrigerant boils and vaporizes in the _______ in a compression refrigeration system.A. liquid receiverB. compressorC. condenserD. cooling coil1745.Since heat will not flow freely from a body at a _______ temperature to another at a _______ temperature, it is necessary to expend mechanical work, heat, or electrical energy from an external source to achieve refrigeration.lower; highershallower; deeperlarger; smallerhigher; lower1746.In a compression refrigeration plant the refrigerant flows from the expansion valve and through the ______ where it absorbs heat from the space being cooled and becomes a gas or vapor.compressorcondenserthrottle valveevaporator1749.Latent heat changes the _______ of water.physical statetemperatureatmospheric pressuresensible pressure1750._______ is a process in which the temperature of a space or its contents is reduced to below that of their surroundings.VentilationRefrigerationAir conditioningHeating1751.The thermal expansion valve reacts directly to the ______.temperature in the space being cooledliquid refrigerant pressure at the solenoid valvepressure drop across the evaporator coilsrefrigerant gas superheat at the coil outlet1752.The heat removed from the refrigerant in the condenser of a refrigeration plant is the ______. latent heat of expansionsensible heat of condensationheat of compressionAll of the above1753.A fluid coil will _______ large quantities of heat when it changes state from a liquid to a vapor.A. releaseB. absorbC. developD. regenerate1754.Thermostatic expansion valves can be adjusted for _______.suction pressure onlyhead pressure onlysuperheat onlysuction pressure pressure and box temperature1755.Constant superheat it is maintained at the evaporator outlet of a refrigeration coil by a _______.solenoid valvelow pressure cutout switchking valvethermal expansion valve1756.One function of the thermal expansion valve is to ________.act as a pilot the solenoid valveregulate the amount of refrigerant flow to the coilregulate the water flowturn the compressor the off and on1757.The latent heat of water vapor in air is dependent upon the ______.dry bulb temperaturewet bulb temperaturedew pointdry point1758.When air is at its dew point it is at its _______.lowest absolute humiditylowest relative humidityhighest absolute humidityhighest relative humidity1759.When the temperature of the refrigerant flowing out from the condenser is below the condensing temperature, it is said to be _______.drywetsuper-cooledsuperheated1760.After passing through the expansion valve the refrigerant should be in the sate of ______. vaporliquidsolidNone of the above is true.1761.Which of the following will be desirable properties of refrigerant?non-explosive; (2)non-corrosive; (3)that it does not react with lubricants.(1), (2) and(3).(1) and (2)(1) and (3).(2) and (3)1762.The boiling and condensation points of a refrigerant depend on the ______ exerted up on it. TemperaturePressureVelocityHeat1763.In the condenser, the hot, high pressure refrigerant gas is cooled by the sea water and becomes _______.fresh watervapormixtureliquid1764.In the process of ______, liquid changes into gas.evaporationfrostingcondensingcompressing1765.The refrigerating agent can ______ at low temperature in the evaporator.expandevaporatecondensedistil1766.As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into _______.liquidoily mixtureemulsionvapor1767.Freon 12 which is used to produce intense cold is normally a _______ when at atmospheric pressure and temperature.liquidgassolidwater only1768.The cooler as the liquid becomes, ______.the faster it will evaporatethe slower it will condensethe slower it will evaporatethe faster it will flow1769.The compressor suction line conveys the refrigerant vapor from _______.condenser to evaporatorevaporator to compressorcompressor to condenserNone of the above.1770.The heat gained per pound of refrigerant in the evaporator is known as the _______.latent heat of vaporizationsensible heatrefrigerating effectspecific heat of vaporization1771.The sum of the sensible heat and the latent heat of any substance is known as _______.total heatresidual heatspecific heatsuperheat1772.The heat identified by only a change in temperature is known as _______.sensible heatlatent heattotal heatresidual heat1773.Which of the following terms represents the form of heat removed from the refrigerant in the condenser of a refrigeration system?Latent heat of vaporization.Heat of compression.Superheat.All of the above.1774.The only means of removing the latent heat of condensation from a refrigerant in the normal Refrigeration cycle is by _______.passing it through the expansion valvecondensing refrigerant in the system condenserPassing the gaseous refrigerant through the heat interchanger on the suction side of thecompressormaintaining a high pressure on the system’s receiver1775.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 ______.fusionvaporizationcondensationsublimation1776.Ammonia when used as a refrigerant is valuable because of its high efficiency, it is however ______.toxicflammableexplosiveAll of the above.1777.When subjected to high heat from a open flame, or an electric heating element, which of the listed refrigerants will break down and produce phosgene gas?CO2.Methyl chloride.R-22.Sulphur dioxide.1778.R-12 is generally considered to be a safe, nontoxic, nonflammable, and non-explosive refrigerant. It can, however, become highly toxic when _______.A. superheated outside the systemB. in contact with an open flameC. heated to the boiling pointD. All of the above.1779.Some chlorinated fluorocarbon refrigerants may decompose into a toxic irritating gas if it is _______.stored at temperatures below 60 degrees Fahrenheitcharged into a system having copper fittingallowed to mix with compressor oilexposed to an open flame or hot surface1780.The heat required to change a substance from a liquid to a gas without experiencing a temperature change, is defined as the latent heat of ______.fusionvaporizationsublimationcondensation1781.Saltwater is typically provided to a refrigeration system to _______.cool the expansion valveprevent refrigerant superheatingcondense the refrigerant gasprevent motor overheating1782.The tendency of a flammable liquid to vaporize is indicated by its ______.ignition temperatureflash pointflammable rangeconvection index1783.Which of the listed characteristics can be applied to R-12 vapor?It is corrosive.It is odorless.It is visible as a blue fog.It has a distinctive taste.1784.The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to _______.increase the refrigerating effect, by decreasing the amount of flash gasallow the refrigerant to enter the throttling device in a saturated conditionincrease the refrigerating effect by increasing the amount of flash gasminimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side1785.Sub-colling is a method of reducing the temperature of the liquid refrigerant below its _______.freezing pointfloc pointcondensing temperaturecompression temperature1786.Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system as a ______.liquiddry saturated gaswet saturated gassuperheated vapor1787.Refrigerant enters the condenser as a ______.high pressure liquidlow pressure vaporhigh pressure vaporlow pressure liquid1788.The refrigerant gas returning to the compressor should be ______.superheatedsaturateddenseflooded1789.The low pressure side of a refrigeration system is considered to exist from the ______. expansion valve to the compressorreceiver to the expansion coilexpansion valve to the evaporatorcondenser to the expansion valve1790.The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the ______.condenservapor generatoraccumulatorevaporator1791.Which of the following best describes the thermodynamic effect on the pressure and volume relationship with regards to saturated gases?As pressure decreases, volume increases.As volume increases, pressure increases.As volume decreases, pressure decreases.As pressure increases, volume increases.1792.The refrigerant leaves the evaporator of a refrigeration system as a low pressure _______. Sub-cooled liquid.High temperature liquid.Oil saturated liquid.Superheated vapor.1793.The temperature of a refrigerant gas is the highest ______.at the compressor dischargeat the compressor suctionin the expansion valvein the receiver1794.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?The condenser and the low pressure side of the cycle?The king valve and the solenoid valve.The compressor and the expansion valve.The condenser and the solenoid valve.1795.Which of the listed refrigeration system components keeps the refrigerant circulating through the system?Expansion valve.Condenser.Evaporator.Compressor.1796.When refrigerant leaves the receiver, it flows next on to the ______.evaporator coilsliquid strainercompressorcondenser1797.Refrigerant is circulated through a refrigeration system by the ______.compressorcondenserexpansion valveevaporator1798.The temperature of the refrigerant in the evaporator coil depends mostly upon the ______. refrigerant pressure in the evaporatorcooling water temperature to the condenserheat load in the refrigerator compartmentsolenoid valve in the liquid line1799.Which of the following terms would best describe the temperature at which a liquid boils at a given pressure?Degree of saturationSaturation temperatureSuperheated temperature.Degree of superheat.1800.A refrigerant with oil in solution has a _______.A. higher boiling temperature for a given pressure than does a pure refrigerantB. lower boiling temperature for a given pressure than does a pure refrigerantC. boiling pressure equal to that of a pure refrigerant at a given pressureD. boiling point will not be affected by entrained oil1801.Machinery operating features are designed to help conserve energy. Which of the following results will not contribute to energy conservation?Reduction of friction.Insulation of hot surfaces.Lubrication of moving parts.Elevation of cooler outlet temperatures.1802.In a compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease in the _______.evaporatorcompressorexpansion valvecondenser1803.Which of the listed statements is correct concerning refrigeration systems?Dehydrators must be used continuously in a refrigeration system.A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24hours.A thermostatic expansion valve is used to control refrigerated space temperature.The liquid receiver functions to collect and remove non-condensable gases.1804.Which of the following modes of heat transfer does NOT require any _______ physical contact between a warmer and a cooler substance?Radiation.Conduction.Natural convection.All of the above.1805.The movement of heat within a fluid, caused by the application of thermal energy, is called ______.radiationconductionconvectioncondo-radiation1806.Which of the listed methods of heat transfer takes place when two substances of different temperatures are in physical contact with each other?Radiation.Conduction.Convection.Each of the above.1807.Which of the following conditions must exist for heat to flow from one object to another? The two objects must be in physical contact.The two objects must be the same size.There must be an existing temperature differential.There must be an existing weight differential.1808.Thermal energy in transition is also referred to as ______.heatpowerhorsepowerfoot-pound1809.The energy associated with molecules is known as ______.kinetic energypotential energymechanical energythermal energy1810.Which of the following forms of energy is demonstrated through the process of combustion? Chemical energy.Mechanical energy.Thermal energy.Electrical energy.1811.The rate of heat transfer from a hot region to a cold region is affected most by the _______. size of the heat sinktemperature difference between the regionssize of the heat sourcetotal heat of the system1812.Which of the following statements is correct concerning heat transfer?Heat is given off from a high temperature region known as a heat sinkHeat transfer rate is affected most by the size of the heat sink involved.Heat transfer rate is affected most by the temperature difference between the heat source and the heat sink.Heat transfer by radiation will occur only by mass motion of a fluid substance.1813.The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will _______.remain constant along the tube’s lengthbe greatest in a single pass counter flow the exchangerremain constant throughout the heat exchangervary from section to section through out the heat exchanger1814.The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is msallest in which of the flow designs listed?Cross.Parallel.Counter.Circular.1815.The general purpose of a heat exchanger is to ______.eliminate hot air from the condensermaintain steady pressure in a systemheat, or cool one fluid by means of another fluidreduce the engine room temperature in the tropical climates1816.Thermostatic expansion valves can be adjusted for ______.suction pressure onlyhead pressure onlysuperheat onlysuction pressure and box temperature1817.Every liquid has a pressure at which it will vaporize and this pressure varies with temperature. The word “which” means ______.a liquida pressurea temperatureNone of the above.1818.A condenser is a vessel in which ______ is deprive of its latent heat of vaporization and so changed to its liquid state.A. sea waterB. fresh waterC. vapourD. gas1819.Which of the statements listed concerning heat transfer is correct?Heat is always transferred at a constant rate.Heat transfer rate increases as temperature difference increases.The rate of heat transfer is not affected by temperature of difference.The high temperature region is known as a heat sink.1820.CFC refrigerants exposed to high temperature or direct flame, will decompose and may produce _______.methyl chlorideammoniahydrofluoric acidozone1821.The compressor suction line conveys the refrigerant vapor from _______ to _______. condenser; evaporatorevaporator; compressorcompressor; condenserNone of the above.1822.What is the function of thermostatic expansion valve in a compression refrigeration system? Nonexistent.For controlling pressure.For controlling superheat.For controlling the solenoid valve.1823.In a vapor compression refrigeration the evaporating pressure is maintained constant by the action of the ______, which removes vapor from the evaporator at the same rate at which it is formed.evaporatorcompressorcondenserNone of the above.1824.What separate the high pressure side from the low pressure side in a refrigeration system? Condenser and thermal expansion valve.King and solenoid valves.Compressor and thermal expansion valve.Condenser and solenoid valve.1825.The thermal expansion valve controls the amount of refrigerant that is allowed to flow to the ______.compressorcooling coilscondenserreceiver1826.The expansion valve on a Freon system controls the ______.superheat of the gas leaving the compressorback pressure in the evaporatortemperature of the iceboxsuperheat of the gas leaving the evaporator1827.In a compression refrigeration plant the refrigerant is under low pressure in the and under high pressure in the _______.compressor/condensercondenser/evaporatorthrottle valve/evaporatorevaporator/condenser1828.The boiling and condensation points of refrigerant mainly depend on the _______ exerted uponi it.temperaturedensityvolumepressure1829.In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the ______. compressorcondenserreceiverevaporator2.3.3 船舶空调系统的组成及主要设备1830.______ is the circulation and refreshing of the air in a space without necessarily a change of temperature.RefrigerationAir conditioningVentilationHeating1831.The device used for low-pressure control and high-pressure cutout on a compressor is called ______.cutoutcontroller switchpressure controllercutout switch1832.A purge recovery system is used in a central air conditioning or refrigeration system to_______.A. purge lube oil from the liquid refrigerantB. recover water purged from the systemC. separate for gases from the receiverD. purge non-condensable gases without losing refrigerant1833.The ______ only allows for adjustment of temperature in each room by the occupant manually controlling the air volume admitted.central air conditioning systemhigh velocity systemlow velocity systemsingle duct system1834.The man distribution duct in an air conditioning system which contains the cooling coils and filters is called the _______.manifoldcondenserchamberplenum1835.________ is the control of temperature and humidity in a space together with the circulation, filtering and refreshing of the air.RefrigerationAir conditioningVentilationHeating1836.______ is used for sensing the temperature of the room in the air condition system.An expansion valveAn evaporatorA thermostatA condenser1837.The process of removing moisture from air is known as ______.humidificationdehumidificationvaporizationevaporation1838.Increasing the moisture content of conditioned air is known as _______.moisturizingdehumidificationdampeninghumidification1839.Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be ______ to maintain ambient conditions within the comfort zone by air conditioning. possiblenecessarypracticableimpracticable1840.A re-heater in an air conditioning system functions to _______.A. control inlet air temperatureB. control inlet air volumeC. maintain relative humidity at 15%D. restore conditioned air temperature to a comfortable level1841.The effective temperature of air is dependent upon _______.(I)relative humidity(II) air velocity.(I) only.(II) only.Both (I) and (II).Neither (I) nor (II).1842.Which of the fluids listed is normally used to condense the primary refrigerant in a shipboard central air conditioning system?Air on nitrogen.Seawater or fresh water.Sodium nitrate brine.Calcium sulfate brine1843.A re-heater, as used in an air conditioning system, is designed to control the ______.A. chilled water temperatureB. dew point temperatureC. primary air temperatureD. dry bulb temperature1844.With ducted air conditioning systems, the modern tendency is to the ______.central air conditioning systemhigh velocity systemlow velocity systemsingle duct system1845._______ is defined as the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.Air conditioningRefrigerationHeatingVentilation1846.Which one is not the component of a typical marine pattern self-contained unit?A centrifugal fan.A direct expansion cooler.A hermetic compressorA centrifugal pump1847._______ is used in typical marine pattern self-contained unit.A water cooled condenserMaking person upsetAdjusting the air humidity.Adjusting the air temperature.2.3.5 船舶空调装置的运行管理1849.In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by _______.increasing refrigerant pressure in the coilincreasing chilled water flow through the coolersub-cooling the refrigerant in the condensersuperheating the refrigerant in the compressor1850.The opening of the humidifier’s valve of air-conditioner should be ______. When the temperature is lower than 0℃.decreasedincreasedfixedclosed1851.The process of adding moisture to air to increase the relative humidity is known as _______. sublimationdesiccationhumidificationmoisturization1852.The humidity of the atmosphere can be determined by the use of the ______.anemometermanometerpotentiometerpsychrometer1853.To add refrigerant to the high side of an air conditioning system, you should introduce the refrigerant through the _______.discharge service valve as a vaporsuction service valve as a liquidcharging valve as a liquidcondenser purge valve as a vapor1854.The humidifier’s valve of air-conditioner should be ______. When the temperature is 5-8℃in the winter.decreasedincreasefixedclosed1855.The air-conditioner is running in the winter and to be stopped. We should ______.close Fan and Humidifier at the same timefirst close Fan and then close humidifier immediatelyfirstly close humidifier and then close Fan immediatelyfirstly close humidifier and then close Fan after 30 seconds1856.When starting air-conditioner in the winter. We should open ______ in sequence.valve of warming;valve of humidifier;fan.(III), (II), (I).(III), (I), (II).(I),(III),(II)(II), (III), (I).1857.One of the functions ventilation is to _______ the humidity of spaces containing sources of moisture, or to _______ the temperature of spaces not mechanically cooled such as the engine room.increase; reducereduce; increaseincrease; increasereduce; reduce1858.The inner part of the condenser should be cleaned with ______.gas oildiesel oilchemical compoundFreon-121859.The quantity of cooled air delivered by an air conditioning unit should ______ the sun of the quantity of air re-circulated to the unit and the quantity mechanically exhausted.balancenot balancebe more thanbe less than1860.In extreme weather conditions, either hot or cold, control of the air conditioning plant presents ______ difficulties.fewlittlea littleless1861.To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, you should ______.admit only enough fresh outside air to provide proper ventilationreduce the air reheating system loadlower the compressor head pressureoperate the purge recovery unit continuously1862.To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the _______.suction service valve as a vaporsuction service valve as a liquiddischarge service valve as a vaporcharging valve as a liquid1863.A lower thermostatic temperature setting will provide a desired degree of comfort in a room where ______.A. low relative humidity is maintainedB. triple banded squirrel cage fans are usedC. air circulation is a maximumD. high relative humidity is maintained1864.In an air conditioning system, moisture is removed from the air by ______.filersseparatorsducted trapsdehumidifiers1865.Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include ______.changing the air filterrecharging the systemchanging compressor lubricantrenewing container vacuum1866.As the amount of moisture in the air increases, the difference between the dry bulb and wet bulb temperature will _______.increasedecreaseremain unchangedbe greatest at dew point1867.A cargo hold has been determined to have a relative humidity of 80% and a dry bulb temperature of 80℃. When the hold is sealed and the dry bulb temperature decreases, the relative humidity in the space will ______.A. decreaseB. increaseC. decrease to zeroD. remain unchanged1868.In order to achieve greater dehumidification with an air conditioning system, you should _______.(i) reduce the cooling;(ii). Temperature increase the re-heater temperature.(i) only(ii) onlyBoth (i) and (ii).Neither (i) nor (ii).1869.Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?Cooling the air to a temperature just above dew point.Heating the air to a point at which moisture will boil off, then re-cooling it.Cooling the air to a point below dew point, then reheating it.Heating the air and then cooling it to a point below dew point.1870.Which of the following methods is normally used to control the temperature of air distributed from individual cooling coils in an air conditioning system using a chilled water circulation system?A. A room thermostat activates an electric heater at each individual chilled air outlet whennecessary.B.Varying the number of passes the air makes across the coils.C.Varying the temperature of the water through the coils.D.Varying the quantity of water flowing through the coils.1871.Most air conditioning units have ______ for adjusting the ratio of recirculated fresh air. Care must be taken not to reduce the fresh air so that stuffiness or smells arise.A.catch platesB.dampersC.regulatingD.fans。