上海理工大学 制冷原理与装置 2003考研真题
暖通空调、制冷低温、热能工程,同济历年真题
3、
1、余容比为0.04的压气机空气进口温度为17℃，压力为0.1MPa，每分钟吸入空气5m3，经不可逆绝热压缩后其温度为207℃，压力为0.4MPa。若室内温度为17℃，大气压力为0.1MPa，求（1）此压气机容积效率；（2）压气机压缩过程的绝热效率；（3）压气机实际耗功率；（4）压缩过程的作功能力损失。设空气比热容为定值，cp=1.004kJ/kg·K，R=0.287kJ/kg·K。（10分）
2、某理想气体自状态1经历一可逆多变过程到达状态2，其温度下降，熵增大，则气体（）
A.压力升高、比容增大，对外作正功；
B.压力降低、比容增大，对外作正功；
C.压力升高、比容减小，对外作负功；
D.压力降低、比容减小，对外作负功。
3、实际气体的压缩因子Z定义为Pv/(RT)，其值（）
（A）>I；（B）<I；（C）=I；（D）不同气体在不同条件下可大于、等于、小于1
(A)升高；（B）降低；（C）不变；（D）（A）（B）（C）都有可能。
14、压力p1=1MPa，温度T1=473K的空气流可逆绝热流经缩放喷管，已知喷管喉管截面上温度Tc=394K，出口截面上温度T2=245K，则喷管各截面上最大流速Cmax为（）
A. Cmax= =313m/s
B. Cmax= =399m/s
6．比较开口系统和闭口系统焓的异同点。
7．如果进行高压比大流量的压缩制气过程，采用什么方法较为合理？
8．空气冷却塔中，用环境温度下地空气可以讲热水冷却到比环境温度更低温度的状态，试问是否违背热力学第二定律，为什么？
2、
1、在某绝热不可逆循环空气压缩制气过程中，气体的压力由p1=0.1MPa提高到p2=1.2MPa，耗功量为35kW，设空气的定压质量比热cp为常数，初温为20℃，气体流量为500kg/h。求：排放气体的温度和过程的当量绝热指数。
上海理工大学能动学院复试专业课真题试卷
1.列出两种制冷空调新技术，简述这些新技术的特点。
答：我国现代化过程中面临能源短缺的问题。
因此，目前国家倡导节能减排提倡使用清洁优质高效能源，大力推广节能环保新技术。
对于制冷与空调行业，应注重新技术的研发和应用，以及制冷空调技术与相关技术的融合与交叉，以适应二十一世纪的能源战略新需要。
一、天然制冷剂的研究目前在天然制冷剂中以氨、丙烷与其他烃的混合物及CO2制冷技术，其中CO2制冷技术最有可能成为R22的长期替代物。
由于CO2的高密度和低粘度，CO2的流动损失小，传热效果好。
通过强化传热可以弥补它循环不高的缺点，增加回热器或者采用两级压缩即可达到与常规制冷剂相似的效率，而不设膨胀机，这也是各公司开发CO2小型制冷或者汽车空调的研究方向。
二、热声制冷技术热声制冷是21世纪以来发展的一种新的制冷技术,与传统的蒸汽压缩式制冷系统相比,热声热机具有无可比拟的优势:无需使用污染的制冷剂,而是使用惰性气体或其混合物作为工质,因此不会导致使用的CFCS或HFCS臭氧层的破坏和温室效应而危害环境;其基本机构是非常简单和可靠,无需贵重,上具有很大的优势;它们无需振荡的活塞和油密封或润滑,无运动部件的特点使得其寿命大大延长。
热声制冷技术几乎克服了传统制冷系统的缺点,可成为下一代制冷新技术的发展方向。
所有的热声产品的工作原理都基于所谓的热声效应,热声效应机理可以简单的描述为在声波稠密时加入热量,在声波稀疏时排出热量,则声波得到加强;反之声波稠密时排出热量,在声波稀疏时吸入热量,则声波得到削弱。
当然,实际的热声理论远比这复杂的多。
三、太阳能空调阳能制冷具有很好的季节匹配性,夏季,天气越热,空调的负荷越大,需要的制冷量就越大,而此时太阳幅射最强,提供的热能最多,太阳能空调提供的冷量也就最高。
冬季,太阳能辐射减弱,但所需的制热循环水温度不高(65℃即可),在满足制冷工况的集热面积下,同样能满足制热负荷要求;这一特点使太阳能制冷技术受到重视和发展。
制冷原理与设备试题
《制冷原理与设备》试题库第一部分：英文试题库PART1. English test for Refrigeration and AirConditioning1.Thermostatic expansion valve are ____________.A.either all the way open or all the way closedB.normally openC.throttled depending on loadD.controlled by suction pressure2.Which of the following may cause that excessively warm water leaves the condenser in a refrigeration plant?①too little cooling water;②too much cooling water;③too warm cooling water.A.①onlyB.any of ①,②and③C.either ①or③D.either ①or②3.If a refrigeration compressor is running continuously without lowering temperature as normal in the refrigerator .the trouble may be ________ .A .excessive condenser cooling waterB.warm food in the refrigeraterC.a shortage of refrigerantD.a shortage of compressor oil4.The color of the flame on a halide torch without any refrigerant present is _______ .A.blueB.greenC.orangeD.purple5.Ihe compressor suction line conveys the refrigerant vapor from ________ .A.condenser to evaporatorB.evaporator to compressorpressor to condenserD.none of the above6.A thermostatic expansion valve is properly controlling evaporator superheat .adjusting this valve to lower the superheat will result in a/an __________ .A.evaporator pressure decreaseB.evaporator coil over-feedC.evaporator capacity increaseD.evaporator valve diaphragm rupture7..The refrigeration system low pressure cutout switch is actuated by _________ .A .an electric system mangerB.a sensing bulb at the tail coil of the evaporatorC.pressure changes in the suction lineD.failure of the king solenoid valve8.The sensing line for the low pressure cutout switch to a refrigeration system is located_____.A.in the chill boxB.before the receiverC.on the suction side of the compressorD.on the discharge side of the compressor9. In the production of freshwater from seawater through a process of heating and cooling, the cooling phase of production is usually called_____.A.evaporationB.distillationC.dehydrationD.condensation10. The heat gained per pound of refrigerant in the evaporator is known as the___.tent heat of vaporizationB.sensible heatC.refrigerating effectD.specific heat of vaporization11. The process of removing moisture from air is known as_____.A.humidificationB.dehumidificationC.vaporizationD.evaporation12. If air at 95 centigrade degree dry temperature and 50% relative humidity is conditioned to 75 centigrade degree dry bulb temperature and 50% relative humidity, it is an example of___.A.cooling onlyB.cooling and humidifyingC.cooling and dehumidifyingD.adiabatic cooling13. When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called____.A.flooding backB.superheatingC.overflowingD.recycling14. Increasing the moisture content of conditioned air is known as____.A.moisturizingB.dehumidificationC.dampeningD.humidification15. The sum of the sensible heat and the latent heat of any substance is known as___>A.total heatB.residual heatC.specific heatD.superheat16. The heat identified by only a change in temperature is known ass_______.A.sensible heattent heatC.total heatD.residual heat17. In reference to air conditioning, when air attains the maximum amount of moisture it can hold at a specific temperature, it is said to be ____.A.superheateeB.saturatedC.condensedD.convected18. Which of the following terms represents the form of heat removed from the refrigerant in the condenser of a refrigeration system?tent heat of vaporizationB.Heat of compressionC.SuperheatD.All of the above19. The dew point of air is reached when the wet bulb temperature is __.A.twice the dry bulb temperatureB.10”C above the dry bulb temperatureC.5”c above the dry bulb temperatureD.equal to the dry bulb temperature20. The temperature at which water vapor in the atmosphere begins to condense is called the ___.A.dew point temperatureB.condensation temperatureC.psychometric temperatureD.absolute humidity temperature21. The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by __.A.passing it through the expansion valveB.condensing refrigerant in the system condenserC.passing the gaseous refrigerant through the heat interchanger on the suction sideof the compressorD.maintaining a high pressure on the system’s receiver22. The heat require to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of ____.A.fusionB.vaporizationC.condensasionD.sublimation23. The amount moisture in a given sample of air, when compared with the amount of moisture the air could hold if totally saturated at the existing temperature of the sample, is called___>A.absolute humidityB.specific humidityC.effective humidityD.relative humidity24. Ammonia when used as a refrigerant is valuable because of its high efficiency , it is however____.A.toxicB.flammableC.explosiveD.all of the above25. R-12 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 above26. A refrigeration system contaminated with moisture can be affected by ___.A.acid formationB.sludge formationC.ice in the expansion valveD.All of the above27. Moisture is removed from a refrigeration system by __.A.bleeding refrigerant form the condenserB.opening a drain petcock on the oil separatorC.condensing the water in the heat exchangering a dehydrator cartridge28. Moisture in the refrigerant may _.A.freeze on the expansion valve seat and reduce the flow of liquid refrigerantB.emulsify the oil in the condenserC.freeze in the king valveD.clog the oil trap29 Moisture in a refrigeration system can cause________.A.freezing the expansion valve closedB.corrosion of system pipingC.improper temperature regulationD.all of the above30. Most solenoid valve are actuated by___.A,. a springB. an electromagnetC. the force of gravityD. refrigerant pressure31. A refrigeration system compressor crankcase is sweating or unusually cold. This is an indication of ________.A.a shortage of refrigerant in the systemB.air in the systemC.an accumulation of liquid refrigerant in the crankcaseD.a shortage of oil in the crankcase32. If a refrigeration system compressor crankcase is sweating, you should _.A.add refrigerant to the systemB.adjust the thermal expansion valve to the proper settingC.adjust the float valve to the proper holding pressureD.open the hand expansion valve33. The sensible heat of air is dependent upon the_______.A.dry bulb temperatureB.wet bulb temperatureC.saturation temperatureD.water vapor superheat34. If a refrigeration compressor were short cycling on the low pressure cutout switch , the probable cause for this might be the ____.A.system was overcharged with refrigerantB.high pressure switch was improperly adjustedC.expansion valve strainers were fouledD.suction valves were leaking slightly35. A refrigeration unit will tend to short cycle when operatin_______.A.under heavy loadsB.during hot gas defrostC.under light loadsD.during starting conditions36. If a refrigeration compressor will not start , the reason may be ______.A.the pressure regulating valve is not closingB.an excessive lack of refrigerant in the systemC.badly leaking discharge valveD.worn piston rings37. Air compressors are equipped with unloading system for the purpose of ______.A.removing all but the frictional load during staringB.relieving intercoolers of high temperature buildupsC.providing high starting torque in the drive motorD.seating valve plates during compressor shutdown38. Air entering an air-cooled refrigeration system is indicated by ______.A.frosting of the liquid lineB.higher than normal head pressureC. a clear sight glassD.abnormally cold reefer boxes39. Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to _.A.maintain adequate coil back pressureB.prohibit flashing in the liquid lineC.reduce refrigerant volume in the systemD.reduce compressor discharge line loading40. The principle purpose of sub-cooling liquid refrigerant prior to its entering theexpansion valve is to __.A.increase the refrigerating effect by decreasing the amount of flash gasB.allow the refrigerant to enter the throttling device in a saturated conditionC.increase the refrigerating effect by increasing the amount of flash gasD.minimize the temperature drop of the liquid as it passes through the solenoid valveto the outlet side41. Sub-cooling is a method reducing the temperature of the liquid refrigerant below its____.A.freezing pointB.floc pointC.condensing temperaturepression temperature42. Refrigerant enters the condenser as a______.A.high pressure liquidB.low pressure vaporC.high pressure vaporD.low pressure liquid43. In a refrigeration system , the amount of refrigerant admitted to the evaporator is directly related to _.A.the compressor discharge pressureB.condenser cooling water temperatureC.the solenoid valve differential pressureD.the superheat of the refrigerant in the tail coil44. The refrigerant gas returning to the compressor should be__.A.superheatedB.saturatedC.denseD.flooded45.The low pressure side of a refrigeration system is considered to exist from the ___.A.expansion valve to the compressorB.receiver to the expansion coilC.expansion valve to evaporatorD.condensor to the expansion valve46. The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is know as the___.A.condenserB.vapor generatorC.accumulatorD.evaporator47. The refrigerant leaves the evaporator of a refrigeration system as a low pressure___.A.sub-cooled liquidB.high temperature liquidC.oil saturated liquidD.superheated vapor48. The temperature of a refrigerant gas is the highest___.A.at the compressor dischargeB.at the compressor suctionC.in the expansion valveD.in the receiver49. Which of the listed refrigeration system components keeps the refrigerant circulating through the system ?A.Expansion valveB.CondenserC.Evaporatorpressor50. When refrigerant leaves the receiver , it flows next on to the ___.A.evaporator coilsB.liquid strainerpressorD.condenser51. Refrigerant is circulated through a refrigeration system by the __.pressorB.condenserC.expansion valveD.evaporator52. 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 line53. An increase in the heat load to a refrigeration system will cause___.A.the suction pressure to decreaseB.the suction temperature to increaseC.increased ice formation on the evaporator coilD.excessive short cycling of the compressor54.A refrigerant with oil in solution has a ____A.higher boiling temperature for a given pressure than does a pure refrigerantB.lower boiling temperaure 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 oil55. In a compression refrigeration cycle, the temperature of the liquid refrigerant experience its greatest decrease in the ___.A.evaporatorpressorC.expansion valveD.condenser56. Which of the following statements concerning energy is corrce?A.Energy can be created or destroyedB.Energy may not be transformedC.The total quantity of energy in the universe is always the sameD.None of the above57. Which of listed statements is correct concering refrigeration system?A.Dehydrators must be used continuously in a refrigeration systemB. A 25 ton refrigeration system has the same cooling effect as melting 25 tons of icein 24 hoursC. A thermostatic expansion valve is used to control refrigerate space temperatureD.The liquid receiver functions to collect and remove non-condensable gases58. If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be__.A.a shortage of compressor oilB.warm food in the refrigeratorC.excessive condenser cooling waterD.a shortage of refrigerant59 Which of the listed method heat transfer takes place when 2 substances of different temperatures are in physical contact with each other?A.RadiationB.ConductionC.ConvectionD.Each of above60. In the refrigeration system, a shortage refrigerant is indicated by __>A.The 2 objects must be in physical contactB.The 2 objects must be in the same sizeC.There must be an existing temperature differentialD.There must be an existing weight differential61.Condensate must be drained from the intercooler and after-coolers of an air compressor because__.A.the cooling effect of the condensate reduces the compressor’s efficiencyB. a danger of explosion exists whenever water is present in a compressorC.water causes erratic operation pneumatic componentsD.the volumetric capacity of the 1st stage is reduced if water remains62. If a refrigeration system were short of refrigerant, the condition would result in __.A.continuous running of the compressorB.high suction pressureC.high discharge pressureD.short cycling of the compressor on the water failure switch63. Noise in a refrigeration compressor can be caused by __.A.worn bearings and piston pinsB.slugging due to flooding backC.too much oil in circulationD.All of the above64. In a refrigeration system equipped with a reciprocating compressor and a water cooled condensing unit , leaking compressor discharge valves will result in ___.A.refrigerant flooding of the compressorB.low suction pressureC.noisy compressor operationD.low head pressure65. Which of the following statements is correct concerning heat transfer?\A.Heat is given off from a high temperature region knows as a heat sinkB.Heat transfer rate is affected most by the size of the heat sink involvedC.Heat transfer rate is affected most by the temperature difference between the heatsource and heat sinkD.Heat transfer by radiation will occur only by mass motion of a fluid substance66. When a refrigeration compressor has developed a high head pressure as a result ofa refrigerant overcharge, you should __.A.increase the amount of cooling water to the condenserB.decrease the amount of cooling water to the condenserC.add more refrigerant to the systemD.remove some refrigerant from the system67. If the suction pressure at the refrigeration compressor is below normal, the cause can be __.A.refrigerant overchargeB.overfeeding by the expansion valveC. a restricted suction strainerD.due to short cycling of the compressor68. The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will __A.remain constant along the tube’s lengthB.be greatest in a single pass counter flow heat exchangerC.remain constant throughout the heat exchangerD.vary from section to section through out the heat exchanger69. The general purpose of a heat exchanger is to __.A.eliminate hot air from the condenserB.maintain steady pressure in a systemC.heat, or cool one fluid by means of another fluidD.reduce the engine room temperature in tropical climates70. An increasing head pressure in a refrigeration system ,without any corresponding change in the cooling water inlet temperature, would probably be caused by__A.restriction in refrigerant pipingB.air and non-condensable gases in the condenserC.water in the refrigerantD.flooding back of liquid refrigerant from the evaporator71. If the refrigeration compressor was developing higher than normal discharge pressure. This could be a result of ____A.air or non-condensable gases in the systemB.leaking discharge valuesC.leaking suction valuesD.liquid refrigerant flooding back from the cooling coil72. If the head pressure of a reciprocating refrigeration compressor is excessive ______A.the relief value should open before the high pressure cutoutB.the relief value should open and allow the excess refrigerant to flow to thereceiverC.the high pressure cutout switch should operate before the relief value opensD.you should close in on the suction value73. One cause of high head pressure occurring in refrigeration system can be ___A.insufficient cooling water flow to the condenserB. a low refrigerant charge in the systemC.the liquid value is open too muchD.high evaporator superheat74. Low compressor head pressure in a refrigeration system can be caused by ____A.insufficient condenser cooling waterB.excessive condenser cooling waterC.condenser clogged or fouledD.high pressure cutout switch inoperative75. A pressure drop through the refrigerant liquid line may cause______A.solenoid value to seizepressor to huntC.formation of flash gas in the liquid lineD.expansion value to freeze open76. If the thermal bulb of an expansion value is incorrectly placed at the center of the coil instead of the end ,it will___A.increase the capacity of the coilB.increase the superheat at the bulbC.deliver more refrigerant to the coilD.decrease the capacity of the coil77. Thermostatic expansion values can be adjusted for ___A.suction pressure onlyB.head pressure onlyC.superheat onlyD.suction pressure and box temperature78 The lowest temperature at which the vapor formed from a liquid ignites and continues to burn steadily in the presence of an ignition source is called the___________.A. flash pointB. fire pointC upper explosive limit D. lower explosive limit79．The lowest temperature at which a liquid gives off enough vapor to ignite in the presence of an ignition source is called its _____________.A. boiling pointB. flash pointC. viscosity pointD. toxic point80．The color of a combustible gas indicator is used to determine __________.A. if there is sufficient oxygen to support lifeB. the toxicity of flammable gases or vaporsC. the leaking amount of refrigerant present in refrigeration systemD. the presence of flammable gases or vapors in the air81.______is used to increase the charging air quantity.A. a turbo blowerB. a governorC. a turning gearD. fresh water82.In a modern three-phase A．C．synchronous brushes generator, the excitation winding is on the rotor．That means ______．A．The generator need not excitation．B．The winding on the rotor is for inputting excitation current．C．There are three phase windings on the rotor．D．The generator has brushes．83. Self-excited a.c. generator with ‘error operated’ voltage control systems draw the full excitation power for the machine terminals. This dispenses with the current transformers, reactors and capacitors necessary for accurate compounding, but renders the excitation system vulnerable to variations in its output voltage. Which of the following is correct about the generator mentioned according to the sentences above?A. It consumes no excitation power .B. It has current transformers.C. Components are needed for accurate compounding.D. Its excitation system is vulnerable to voltage variations84. If you ___ the refrigerating equipment more carefully before sail, we ____ so much trouble now.A. examined, are not havingB. had examined, would not haveC. had examined, would not have hadD. should examine, would not have85. This arrangement is ______ if the elements are directly connected to one another and the control action takes place without human involvement．A．a manual closed loop B．a manual opened loopC．an automatic closed loop D．an automatic opened loop 86. Domestic refrigerator is started automatically by ______ which operates as the water level falls to a predetermined level．A．a level controller B．a temperature controllerC．a floating ball D．a pressure switch87. ____thrust and resistance equal each other, the objector always travels at a constant speed.A. As long asB. As far asC. As well asD. Unless88. Safety-management objectives of the Company should establish safeguards ______ all identified risks．A．with B．without C．against D．above89. There is too much water in the lubrication oil，It doesn’t_______ to thespecifications．A．come from B．come in C．come out D．come up 90. The first step you would take in helping an unconscious victim who is not breathing is ______．A．stop bleeding B．open airwayC．mouth-to-mouth respiration D．call for help91. Had computers not been invented, we ____such complicated heat road calculation problems for refrigeration system in a short time.A. could not have solvedB. had not solvedC. didn’t solvedD. solved92._____ in a confined space, we can use carbon dioxide to extinguish it.A. Taking placeB. Having taken placeC. The fire taking placeD. It takes place93. If the voltage remains constant, the more the resistance, the _____the current.A. moreB. greater C little D. less94 ____ allows for a closed discharged valve.A. A reciprocating pumpB. A gear pumpC. A centrifugal pumpD. A vane pump95 Frequent stopping and starting of the refrigerating compressor may be caused by ____.A. high-pressure controller set too highB. excessive loadC. too small differential of the low-pressure controllerD. iced or dirt on evaporator96 If we _____the water to a certain temperature, it _____into steam.A. heated/would turnB. heat/turnedC. had heated/would had turnedD. heat/will turn97.Which of the listed characteristics can be applied to R12 vapor?A. It is corrosive.B. It is odorless.C. It is visible as a blue fog.D. It has a distinctive taste.98.The power factor at which a paralleled AC generator operates is usually adjusted by the ______.A. connected loadB. prime mover speedC. field excitationD. generator's rated voltage99-102：Maintenance and OverhaulingSatisfactory and proper operation of the refrigerating system depends not only on correct operating but also on how well it is kept in order. Regular maintenance of the engine helps a lot in preventing early wear of parts and in ensuring a long service as well as the working efficiency of the engine. With various types of engines, of course, the maintenance and overhaul is different. Instruction books are to be referred to whenever necessary.The individual parts of the engine should be inspected and thoroughly cleanedat regular intervals. The periods for such overhaul work depend largely on the quality of the lubricating oil and fuel, on the load and on the efficiency of the operator in locating troubles and remedying them in time..During overhaul the safety rules have to be observed as required in order to prevent the danger of accidents. Special precaution is necessary when the engine is running with the lagging removed. During overhauls with the engine shut down, safety measures should be taken to avoid undesirable turning of the crankshaft.All pipes should be pressure-relieved before the repair work is started. Read the pressure gauges and /or check the pipes by carefully loosening the screw plugs or connections.If some parts of the running gear are dismantled, before using the turning gear, make sure that no loose parts are jammed in the crankcase where it is easy for them to cause damage.99. According to the passage, which the following factors are involved to keep the engine satisfactory and proper running?A. correct operatingB. keep the system in orderC. refer to the instruction booksD. all of above100. According to the passage, which the following items do influence the periods of the overhauling work?A. the quality of the lubricating oilB. the load of the engineC. the efficiency of the operator in locating troubles and remedying them in timeD. all of the above101. According to the passage, we should take special precaution when ____.A. the engine is running with the removal of laggingB. the engine is shut downC. pipes are removedD. the screw plugs or connections are loosened102. Acco rding to the passage, line 17 the bold and italic word “it” may propabably mean ____ .A. running gearB. turning gearC. crankcaseD. to cause damage103-106：Fresh water is used for the cooling of the cylinder jackets and covers of the compressor, whereas the various cooling liquids which circulate the engine are themselves cooled by sea water,. Such as, sea water is used for the cooling of the oil in the lubricating oil cooler as well as the fresh water. In an emergency situation, for example in the event of damage to a fresh water cooler or generator, the sea water pumps can be used to supply sea water to the fresh water cooling system, merely by removing the blind-flanges.103. From this paragraph, we can see that ____.A. the cylinder jackets and covers are cooled by fresh water and then by sea waterB. fresh water is only used for the cooling of the cylinder jackets and covers of the main engineC. fresh water is used for the cooling of the main engineD. sea water is used for the cooling of both the fresh water and main engine104. . According to the paragraph, the various cooling liquids refer to ____A. fresh water and sea waterB. fresh water and cooling oilC. air and fresh waterD. sea water and air105. In which situation we should use sea water system instead of fresh water system?A. Sea water pumps are damagedB. sea water cooler is damagedC. fresh water pumps are damagedD. the blind-flanges are broken106. The word merely in this paragraph could best be replaced by ____.A. onlyB. necessaryC. butD. if107-110：The lubrication system of an engine provides a supply of lubricating oil to the various moving parts in an engine. Its main function is to enable the formation of a film of oil between the moving parts, which reduces friction and wear. The lubricating oil is also used as a cleaner and in some engines as a coolant. The usual method of bearing lubrication is by forced feed system, which supplies oil to all bearings, so that a film of oil is maintained on the journal and bearing surfaces. 107. The forced feed system is put into use in order to____.A. supply oil to all parts of the engineB. lubricate the bearing and the piston。
制冷试题及答案
制冷试题及答案一、选择题（每题2分，共20分）1. 制冷循环中，制冷剂在压缩机中的状态变化是：A. 从液态变为气态B. 从气态变为液态C. 从气态压缩至高压气态D. 从液态压缩至高压液态2. 在制冷系统中，冷凝器的主要作用是：A. 将制冷剂从气态变为液态B. 将制冷剂从液态变为气态C. 将制冷剂从高压气态变为低压气态D. 将制冷剂从低压液态变为高压液态3. 下列哪种物质不属于常用的制冷剂？A. 氨B. 氟利昂C. 二氧化碳D. 水4. 制冷系统中的膨胀阀主要作用是：A. 降低制冷剂温度B. 降低制冷剂压力C. 增加制冷剂流量D. 减少制冷剂流量5. 制冷量是指：A. 制冷系统每小时消耗的电能B. 制冷系统每小时移走的热量C. 制冷系统每小时产生的冷量D. 制冷系统每小时输出的功率二、填空题（每空2分，共20分）6. 制冷剂在蒸发器中吸收热量，实现________。
7. 制冷循环的四个基本过程包括压缩、冷凝、________和膨胀。
8. 制冷系统中的________是将制冷剂从低压气态变为高压气态的设备。
9. 制冷剂的热力性质中，________是制冷剂在蒸发器中吸收热量的能力。
10. 制冷系统中的________是将制冷剂从高压液态变为低压液态的设备。
三、简答题（每题15分，共30分）11. 简述制冷循环的工作原理，并说明各部件的作用。
12. 描述制冷系统中蒸发器和冷凝器的工作原理及其重要性。
四、计算题（每题15分，共30分）13. 假设一个制冷系统，其压缩机的功率为10kW，制冷剂在蒸发器中吸收的热量为60kJ/kg。
如果制冷剂的流量为2kg/s，计算该制冷系统的制冷量。
14. 给定一个制冷系统，其冷凝器的出口温度为40℃，蒸发器的进口温度为-10℃，制冷剂为R134a。
如果系统的制冷量为100kW，计算该系统的COP（制冷系数）。
答案一、选择题1. C2. A3. D4. B5. B二、填空题6. 制冷剂在蒸发器中吸收热量，实现制冷效果。
制冷试题及答案
制冷试题及答案随着科技的不断发展和社会的进步，制冷技术在我们的生活中起着越来越重要的作用。
制冷试题是评估制冷技术知识和能力的重要方式之一。
本文将为您介绍一些常见的制冷试题，并提供详细的答案解析。
一、选择题1. 冰箱的工作原理是利用哪种物理现象产生制冷效果？A. 热对流B. 蒸发冷却C. 传导导热D. 辐射散热答案：B. 蒸发冷却解析：冰箱利用制冷剂在低压下蒸发吸热，从而使冰箱内部温度降低。
2. 制冷循环中，下列哪个元件起到压缩制冷剂的作用？A. 蒸发器B. 冷凝器C. 压缩机D. 膨胀阀答案：C. 压缩机解析：压缩机将低压制冷剂抽入并增压，使其温度升高。
3. 制冷系统中的负责吸收热量的元件是：A. 蒸发器B. 冷凝器C. 压缩机D. 膨胀阀答案：A. 蒸发器解析：蒸发器处于低压状态，制冷剂在这里吸收热量。
二、判断题1. 制冷剂在物理上不消耗，可循环使用。
答案：正确解析：制冷剂在制冷循环中不消耗，可以循环使用。
2. 空调和冰箱的制冷原理基本相同。
答案：正确解析：空调和冰箱都利用压缩机、蒸发器、冷凝器等元件来实现制冷效果，因此制冷原理基本相同。
三、填空题1. 升华是物质直接从固态转变为气态，而不经过液态的过程。
2. 一个制冷循环由四个基本元件组成，分别是蒸发器、压缩机、冷凝器和膨胀阀。
四、简答题1. 请简要描述制冷循环的工作过程。
答案：制冷循环的工作过程如下：首先，制冷剂通过蒸发器吸热蒸发，从而吸收了冰箱内部的热量，使冰箱内部温度降低。
接着，蒸发好的制冷剂进入压缩机，被压缩机压缩成高压气体，同时温度大幅度升高。
然后，高压气体通过冷凝器，外界的冷空气对其进行冷却，使制冷剂释放热量并变成液体。
最后，液态制冷剂通过膨胀阀，降低压力并转变为低压状态，重新进入蒸发器，开始新的循环。
2. 请给出冷凝器和蒸发器的区别。
答案：冷凝器和蒸发器是制冷循环中的两个重要元件。
冷凝器是在制冷循环中负责冷却高温高压的制冷剂，使其变成液体。
上海理工大学研究生课程(试题类)试卷 (题库)
33.设 ui (i 1, 2,..., n) 是一组关于 n n 维正定矩阵 A 共轭的向量' (u i ) ' Au i
34.设 ui (i 1, 2,..., n) 是一组沿正定二次函数 f(x)最优下降路径共轭的向量,
k i 1 证明:对于所有的 i , 1 i n ， (u , f ( x )) 0, k 1,..., i
Dn ，计算 Dn 效率。
18.用三点等分区间搜索法求 f ( x) x2 4 x 2 在区间[0,10]上的最小值， 完 成前两次迭代。 19.利用牛顿法计算函数 f ( x) 4 x12 2 x1x2 2 x22 x1 x2 的最小值。 20.对于三点等分区间法，求使最终期间和初始区间之间的比为△L 时的 最小计算次数 N。 21.Fibonacci 要将区间缩小到 104 即 Ln / L 104 ， 函数要迭代计算多少次？ 22.证明：黄金分割法和斐波那契搜索法的渐近收敛率是一致的。 23.对于二次函数 f ( x) xT Qx ，当用最优梯度法求解其最小值时，求每一 步迭代过程中的最优步长 k . 24.运用最优梯度算法，确定步长 k ，使 f ( x) 在 k 次迭代中每次都下降一
2 f ( x ) 0
6. 证明：二次函数 f ( x) aT x xT Ax 严格凸的充要条件是 A 是正定阵。 7. 用凸函数的定义证明：函数 在 x 0 是严格凸函数，在 x 0 是严格凹 函数。 8. 用凸函数的定义证明 x 2 是凸函数。 9. 证明：凸函数的和仍为凸函数。 10.判断下列函数是否为严格凸函数
2 2 (1) f ( x1 , x2 ) 2 x1 2 x2 2 x1x2 x2 1
制冷原理及设备题库(含答案)
填空题1．制冷是指用人工的方法将被冷却物的热量移向周围环境介质，使其低于环境介质的温度，并在所需时间内维持一定的低温。
2．制冷是一个逆向传热过程，要实现必须满足热力学第二定律。
3．最简单的制冷机由压缩机、冷凝器、膨胀阀和蒸发器四个部件并依次用管道连成封闭的系统所组成。
4．蒸气压缩式制冷以消耗机械功为补偿条件，借助制冷剂的气化（相变）将热量从低温物体传给高温环境介质。
恒温热源间的理想制冷循环是由绝热膨胀、吸热膨胀、绝热压缩、放热压缩，四个过程组成的逆向循环。
已知氨制冷剂进行理论制冷循环（如图），其状态点参数如下：其单位质量制冷剂的压缩机耗功率为161.6KJ/Kg ，制冷系数为6.665．吸收式制冷以消耗热能为补偿条件，借助制冷剂的气化将热量从低温物体传给高温环境介质。
6．小型氟利昂空调装置一般不单独设回热器，而是将供液管与吸气管包扎在一起，起到回热效果。
7．节流前液体制冷剂的过冷会使循环的单位质量制冷量增大；单位理论压缩功不变。
8．制冷机的工作参数，即蒸发温度、冷凝温度、过热温度、过冷温度，常称为制冷机的运行工况。
9．单级蒸气压缩式制冷循环对压缩比的要求主要有压缩比：≥3 和不宜过大。
10．空调用制冷系统中使用的制冷剂可分为无机化合物、碳氮化合物、氟利昂混合溶液三类。
11．制冷剂氨的代号为R717，其中7表示无机化合物，17表示分子量（17）；水的制冷剂代号为 R718 。
12．制冷剂对环境的影响程度可以用ODP破换臭氧层潜能和 GWP温室效应潜能两个指标表示。
13．根据工作原理，制冷压缩机的型式有容积式制冷压缩机和离心式制冷压缩机两大类。
14．活塞式压缩机按密封方式可分为开启式、半封闭式和全封闭式三类。
15．活塞式制冷压缩机结构包括机体、活塞及曲轴连杆机构、气缸进排气阀组卸载装置等几大部分。
16．活塞式压缩机主要由机体、活塞、汽缸套、连杆、曲轴和排气阀等组成。
17．活塞式制冷压缩机卸载装置包括顶杆启阀机构、油压推杆和机构等三部分。
上海理工
2001年上海理工大学硕士研究生入学考试试题考试科目：传热学准考证号：得分：一、问答题（每题5分）1．有三层平壁组成的复合壁，已测得各层壁面温度依次为600℃、500℃、300℃、60℃，在稳态导热情况下，问哪一层热阻最小？2．说明非稳态可以采用集总参数法求解的条件，并说明其物理意义。
3．怎样才能改善热电偶的温度响应特性？4．直管内紊流对流换热中，其他条件相同时，相同的流速或相同的流量条件下粗管和细管的对流换热系数哪个大？有何证据？5．不凝性气体对膜状凝结换热有什么影响？其机理是什么？6．何为灰体？引入灰体概念对计算辐射换热有什么意义？7．试比较黑表面、温射灰表面、重辐射面的有效辐射和本身辐射的关系。
8．举例说明强化单相强制对流换热的基本思想。
9．从传热观点看，为什么暖气片一般都放在窗户下面？10．试说玻璃温室效应的原理。
二、计算题（一、二题每题13分，第三题14分）1．水以2kg/s的流量流过内径为40mm的管子，管内表面的温度保持100℃。
问需要多长的管子才能把水温从25℃加热到75℃。
（比热Cp=4.141kJ/(kg.k),动力粘度μ=547×10-6N.s/㎡,导热系数λ=0.643W/(m·℃),密度 1000kg/ ,Pr=3.56,不需要修正）2.考察一长4m,宽3m的房间,地板和天花板之间的距离为2.5m,房间的四个墙壁是绝热的,由于使用了电阻加热器使地板表面保持均匀温度30℃,天花板的温度为12℃,地板对天花板的角系数为0.29,若所有表面的黑度都为0.9,问地板与天花板间的净辐射热量是多少?墙壁的温度是多少?3.一台逆流式换热器刚投入工作时在下列参数下运行:热流体进口温度t1′=360℃,出口温度t1″=300℃,冷流体进口温度t2′=30℃ ,出口温度t2″=200℃,热流体的质量流量G1与比热C1的乘积 2500W/℃,传热系数800W/(㎡·℃) .运行一年后发现,在G1C1、冷液体的G2C2 及t1′、t1保持不变的情形下，冷流体只能被加热到162℃，而热流体的出口温度则高于300℃，试确定此情况下的污垢热阻及热流体的出口温度。
2019上海理工大学制冷及低温工程考研经验分享
2019年上海理工大学制冷及低温工程考研经验分享上海理工大学的动力工程及工程热物理专业学科评估为：B+，排名全国十二名，制冷及低温工程方向排名更加靠前，上理工培养出中国第一个制冷及低温工程博士也是首批获得该专业硕博点的学校。
对于本科专业为能源与动力工程或者建筑环境工程的学生来说，上理工制冷是一个不错的选择，制冷在行业内的认可度很高，许多知名制冷企业管理层均是上理工毕业。
我想在江浙沪工作的话，考虑到校友和就业方便的原因，因此选择了这所学校的制冷专业的原因。
目前上海理工大学制冷及低温工程专业近年来报名人数越来越多，2019年报考人数达184人，录取人数为48人，含推免生一人。
复试分数线为320分，是上海理工大学能源与动力工程学院一级学科动力工程及工程热物理下分数线最高的方向，我是考了超过了复试分数线50分以上，最后初试复试综合下来排名也非常靠前，我个人认为考上海理工大学制冷及低温工程专业性价比很高，推荐大家报考。
初试经验考研英语：我个人是过了英语六级的，但是就我身边的情况看，四六级和考研英语关系不大，我主要做的准备是背单词和刷题。
背单词我建议用APP背单词，因为背单词更加科学而且方便，可以提早开始，我是大三上开始背单词的，到了第二年六月份的时候开始做真题，效果会非常好。
一份真题的时间刚开始可以一半一半做，但是建议做完以后要将卷子的文章翻译一遍，记下不认识的单词，历年真题卷的单词重复率很高。
真题和模拟题都可以选用张剑的黄皮书，答案非常细致。
作文部分选择王江涛，模板足够用。
考研数学：考数学一复习高数，概率论，线代。
基础差一点的可以看同济高等数学书，但效率低的话可以看视频，网上有不少考研基础班视频，过一遍开始做题。
我高数和概率论选用的是张宇的高数十八讲，线代选用李永乐的，这三本弄完基础会很扎实，习题方面我推荐用汤家凤的1000题和李永乐的660题，有基础巩固也有难度提升。
练手的题目大概就这么些，最好高数，线代，概率论那三本资料九月份完成，期间穿插习题练习，习题争取在十一月中之前做完，做不完也要开始刷真题了。
2003年上海理工大学管理学考研真题及详解【圣才出品】
2003年上海理工大学管理学考研真题及详解上海理工大学2003年硕士研究生入学考试试题考试科目：管理学一、名词解释(42分)1．管理2．系统3．控制4．效率和效果5．直线关系和参谋关系6．冲突二、问答题(80分)1．请简述目标管理的基本过程。
2．请简述组织文化的结构层次。
3．你愿意在职能型组织工作还是愿意在矩阵式组织里工作?为什么? 4．请画出波特和劳勒激励模式图。
并举例说明它的应用。
5．技术创新包括哪些内容?它对企业的生存和发展有何贡献?三、案例分析题(28分)1994年3月，欧文康宁公司的绝缘部与FAST——市场自动销售系统联机，FAST是一种销售人员自动控制系统，它废弃了官僚控制，授权给销售人员，他们可以自己作出决策。
配备的便携式计算机每台价值5000美元，培训的费用超过了300000美元。
尽管发生了这些费用，但它也带来了很多好处：FAST使销售人员可以得到以前只有管理者才能得到的信息，同时，也使管理者可以更直接地对销售活动进行管理和监控。
FAST包括三种软件：(1)一般的工具——文字处理系统、传真发送系统等，(2)产品信息——顾客特殊需要，价格信息，(3)客户信息—会计信息，购买记录，定货情况，偏好的支付方式。
只要通过调制解调器与公司的计算机中心联网，就可以自动更新信息。
对管理者来说，FAST可以提供最新的销售统计数字和市场的发展趋势。
管理者了解哪些客户在购买什么产品，销售情况如何，销售人员是否在某个区域遇到了麻烦。
这些信息使管理者在事情发生时就了解了情况，可以实时改变战术和战略。
显然，信息技术改变了销售人员和管理者的工作。
通过对员工提供更多的信息，FAST对他们进行授权，使他们可以自行决策。
同时，信息技术使管理者可以更为有效地进行监管，所以管理者的管理范围更广泛了。
结果是现在在欧文康宁公司的管理者只有1986年的一半，并且撤消了整个高级经理层，支持部门也在逐步削减。
在自动化以前，管理者和支持部门主要处理客户投诉，有问题的定单和激化了的问题。