PowerEngineeringThirdClassTestOld3rdTLMModule6student动力工程三级考试试题试卷

Section4Lecture6Try:12.Removeheat

3.Reducefriction

1.Afteranairreceiverisopenedupitshouldbethoroughly

ventilatedbecauseofthechanceofitcontaining:4.Eliminatewatercooling

5.Reducecorrosion

a.Oil6.Removecarbon

b.Water7.Preventwear

c.Carbonmonoxide

d.Carbondioxidea.1,2,3,4,5

b.1,2,3,466,7

2.Avariablespeedcontrolregulatesthespeedofthe_fromc.1,3,4,6

airreceiverpressuremonitoring.d.1,2,3,5,7

a.Driver10.Thereasonsforcoolingtheairinanaircompression

b.Compressorcrankshaftsystemisto:

c.Compressorimpellers

d.Compressorblades1.Removewatervaporandoilvaporfromtheair

3.Whenthecompressorisstoppedandthereisany2.Makecylinderlubricationmoreeffective

likelihoodoffreezing:

3.Decreasetheamountofpowerrequiredto

a.Thewaterjacketsmustbethoroughlydrainedcompresstheair

b.Thewalerjacketsshouldbefilledwithantifreeze4.Removefixedcarbonfromthevalues

c.Openthesteamcoilstothecompressor

d.Disconnectthecoolingwatersupplyfromthe

compressora.2,4

b.1,4

4.Anactualaircompressioncurveofapressure-volumec.1,2,3

diagramis:d.Noneoftheabove

a.SomewherebetweenadiabaticandisothermalSection4Lecture6Try:2

b.Purelyadiabatic

c.Purelyisothermal1.Afteranairreceiverisopenedupitshouldbe

d.Completelyconstantpressurethoroughlyventilatedbecauseofthechance

ofitcontaining:

5.Surgingisknownasaslowcycleofeventsinwhichthe

compressordischargesairandstops.a.Oil

b.Water

TorFc.Carbonmonoxide

d.Carbondioxide

6.ACmotorsareusedwiththevariablespeedcontrolsystem

tocontrolaircompressoroutput.2.Theclearancepocketmethodofunloadinganair

compressoruses:

TorF

a.Clearancepocketsateachendofthecylinder

7.Centrifugalaircompressorsareusedforvolumeb.Thevariablevolumeprinciple

pressureapplicationsc.Aslidevalveunloader

d.Hydraulicallycontrolledinletvanes

8.Inanairdryerusingapressurevesselcontaininga

chemical3.Aircompressorslocatedabovesealevelwill

toabsorbthemoisture,thechemicaliscalledadeliver____thanthoselocatedatsealevel.

a.Airwithlessmoisture

9.Lubricatingoilisnecessaryinanaircompressorinorderb.Alesserweightofair

toperformthefollowingfunctions:c.Airwithmoremoisture

d.Highertemperatureair

I.Providesealing

4.Externallubricationofanaircompressormeans,tod.Alloftheabove

lubricatealltheoutsidemovingparts

ofthecompressor.2.Moistureincompressedairsystemshasadetrimental

effectonairoperatedinstruments

TorFandtools.Itmay:

5.Agoodmethodofdryingairbeforeitgoesintothea.Plugtheairfilter

receiveristoheatit.b.Lowerthecompressedairdischargetemperature

c.Expandintheairreceiverandcauseoverpressuring.

TorFd.Freezeintheairlines

6.Airreceiversshouldbeinspectedregularlyandthen3.Volumetricefficiencyistheratioof:

pneumaticallytested.

a.Dischargevolumecomparedtointakevolume

TorFb.Absolutevolumecomparedtogaugevolume

c.Displacementtocapacity

7.Topreventsurging,theofthed.Capacitytodisplacement

compressormustnotbeallowedtofall

belowthe(2words).4.Axialflowcompressorshavetheairflowthroughthe

compressorfrominlettodischarge

8.Outputfromacompressorusingtheconstantspeedcontrolinaradialdirection.

methodmustusesome

typeofdevice.TorF

9.Inaxialaircompressorsthepressureriseperstageis5.Thedischargepipeofanaircompressorshouldhave

therefore,forhighseveral

pressuresstagesarerequired.dipsorbendsinittotrapthemoistureoutoftheline.

TorF

10.Detrimentaleffectsofmoistureinanaircompression

systemare:6.Aftercoolersshouldbefittedwithpressuregauges,

thermometers,

1.Itmaycausecorrosionandpossiblyasafetyvalve.

2.ItmaycausewaterhammerTorF

3.Itwillreducecompressorcapacity7.Thedualcontrolsystemofcompressoroutputcombines

variablepressure

4.Itwillcooltheairbelowthedewpointwithvariablevolume.

5.ItmaywashcarbonoffthevalvesTorF

6.Itmayfreezeintheairlines

8.Topreventsurging,theofthe

a.1,2,3,6compressormust

b.3,4,5,6notbeallowedtofallbelowthe

c.1,2,3,4,5,6___________(2words).

d.2,4,5,6

9.Whenacompressorisstoppedthecoolingwatersupply

Section4Lecture6Try:3shouldbe(2words).

1.Useofthestartandstopaircompressoroutputcontrolin

conjunctionwiththeconstant10.Thefourmajorpurposesofanairreceiverareto:

speedcontrolsystem:

1.Actasareservoirorstoragevessel

a.Conservesthemotorlife

b.Reduceshighamperagedrawthereforesaving2.Housefittingssuchassafetyvalve,pressure

electricitygauge,andfusibleplug

c.Givesaflexiblecontrolsystem

3.DampenthepulsationsofareciprocatingTorF

compressor

4.Actasacompressoroutputcontrolreference7.Anactualaircompressioncurveiseitheradiabaticor

pointisothermal.

5.Allowmoistureandoilparticlestosettleout

6.AllowfurtherheatingoftheairbeforegoingtoTorF

theuse

8.Atrulyadiabaticaircompressionsystemwouldnothave

a.1,2,5,6anygiven

b.1,3,4,5ortakenfromthecycle.

c.1,2,3,6

d.2,3,4,59.The(twowords)controlmethodcan

beusedwhenthecompressoris

Section4Lecture6Try:4drivenbyasteamengine,aturbine,oraninternal

combustionengine.

1.Eachpairofmovingandfixedbladesinanaxialair

compressorconstitutesa:10.Lubricatingoilisnecessaryinanaircompressorinorder

toperformthefollowingfunctions:

a.Pressuredrop

b.Temperaturedecrease1.Providesealing

c.Programofair

d.Stage2.Removeheat

3.Reducefriction

2.Thetermdynamicdescribesthosecompressorswhich

usetogivevelocity4.Eliminatewatercooling

thenpressuretotheair.

5.Reducecorrosion

a.Turbulance6.Removecarbon

b.Bladesorvanes7.Preventwear

c.Pistons

d.Noneoftheabovea.1,2,3,4,5

b.1,2,3,4,5,6,7

3.Anairfilteronanaircompressorinletpipeisusedto:c.1,3,4,6

d.1,2,3,5,7

a.Reducetheairvelocity

b.KeepoutthemoistureSection4Lecture6Try:5

c.Purifytheairbyremovingexhaustprocessgases

d.Preventdustandotherparticulatefromenteringthe1.Thetermdynamicdescribesthosecompressorswhich

compressorusetogivevelocity

thenpressuretotheair.

4.Aircompressorinterandaftercoolersmaybe:

a.Turbulance

a.Wateroraircooledb.Bladesorvanes

b.Oilorhydrogencooledc.Pistons

c.Teflonlubricatedd.Noneoftheabove

d.Electricallyheated

2.Thestopandstartsystemisbestemployedwhere:

5.Amethodofunloadingareciprocatingcompressoristo:

a.Theairdemandisconstant

a.Holdthedischargevalveclosedb.Theairdemandislowandinfrequentlydemanded

b.Holdthedischargevalveopenc.AlargeACmotorisusedasthedriver

c.Placeacheckvalveinthedischargelined.Adieselengineisusedasthedriver

d.Holdtheinletvalvesintheopenposition

3.Theinletpipetothecompressormustbe:

6.Highintercoolertemperaturecouldbemonitoredto

automaticallyshutdowna.Largerthatthecompressorintake

theaircompressor.b.Twiceaslargeasthecompressorintake

c.Smallerthanthecompressorintake

d.Atleastaslargeasthecompressorintake

10.Thereasonsforcoolingtheairinanaircompression

4.Byfollowingtheadiabaticcurveofanaircompressorsystemisto:

pressure-volumediagram

thedischargepressureis:1.Removewatervaporandoilvaporfromtheair

2.Makecylinderlubricationmoreeffective

a.Attainedlater3.Decreasetheamountofpowerrequiredto

b.Atconstantvolumecompresstheair

c.Attainedearlier4.Removefixedcarbonfromthevalues

d.Noneoftheabove

a.2and4

5.Anaircompressorinstalledatahighaltitudewillrequireab.1and4

highercompressionratiotoc.1,2,3

producethesamedischargepressure,asacompressord.Noneoftheabove

installedatsealevel.

TorF

6.Forchangingtheairincentrifugalair

compressors

tovolutecasingsanddiffuservanesare

implemented.Section4Lecture6Try:6

7.Twosystemsfrequentlyusedtounloadreciprocatingair1.Amethodofunloadingareciprocatingcompressoristo:

compressors

istohavethesuctionorinletorhavetheinleta.Holdthedischargevalveclosed

valveheldb.Holdthedischargevalveopen

c.Placeacheckvalveinthedischargeline

d.Holdtheinletvalvesintheopenposition

8.Internallubricationofaircompressorsrefersto:

2.Toavoidaircompressorexplosionsthesystemshouldbe

1.Thecrankcaseandcrankshaftprovidedwith:

2.Cylinderwallsandpistons

3.Vanesandcasingwallsofsomecompressorsa.Maximumcoolingwaterpossible

4.Impellersofacentrifugalcompressorb.Maximumoilpossibletopreventoverheating

c.Minimumoilnecessaryforadequatelubrication

a.2,3d.Havingthecylinderwallswellinsulated

b.1,3,4

c.3,43.Whenthecompressorisstoppedandthereisany

d.1,4likelihoodoffreezing:

9.Thefourmajorpurposesofanairreceiverareto:a.Thewalerjacketsmustbethoroughlydrained

b.Thewaterjacketsshouldbefilledwithantifreeze

I.Actasareservoirorstoragevesselc.Openthesteamcoilstothecompressor

2.Housefittingssuchassafetyvalve,pressured.Disconnectthecoolingwatersupplyfromthe

gauge,andfusibleplugcompressor

3.Dampenthepulsationsofareciprocating

compressor4.Axialflowcompressorshavetheairflowthroughthe

4.Actasacompressoroutputcontrolreferencecompressorfrominlettodischarge

pointinaradialdirection.

5.Allowmoistureandoilparticlestosettleout

6.AllowfurtherheatingoftheairbeforegoingtoTorF

theuse

5.Thecapacityofanaircompressorcanbecalculatedifthe

a.1,2,5,6displacementandvolumetric

b.1,3,4,5efficiencyoftheaircompressorisknown.

c.1,2,3,6

d.2,3,4,5TorF

6.Anactualaircompressioncurveiseitheradiabaticor3.Afusibleplugisrequiredontheairreceivershellto:

isothermal.

a.Removeunwantedmoistureandoil

TorFb.Ventairifthedischargetemperatureoftheair

compressoristoohigh

7.Centrifugalaircompressorsareusedforvolumec.Venttheairfromthereceiverintheeventofafire

pressureapplications.occurringinthevicinityoftheairreceiver

d.Ventoffairifthereceiverpressureisup

8.Outputfromacompressorusingtheconstantspeedcontrol

methodmustusesometypeofdevice.4.Toavoidaircompressorexplosionsthesystemshouldbe

providedwith:

9.Thewatercooledtypeofintercoolerisofand

constructionwitheithera.Maximumcoolingwaterpossible

coolingwaterpassingthroughthetubesorthecompressedb.Maximumoilpossibletopreventoverheating

airpassingthroughwaterc.Minimumoilnecessaryforadequatelubrication

surrounded.d.Havingthecylinderwallswellinsulated

5.Compressorratiois:

a.Theratioofabsolutedischargepressuretoabsolute

inletpressure.

b.Theratioofgaugedischargepressuretogaugeinlet

pressure.

10.Thefourmajorpurposesofanairreceiverareto:c.Theratioofthefreeairintaketotheabsolute

volumetricdischarge

I.Actasareservoirorstoragevesseld.Alloftheabove

2.Housefittingssuchassafetyvalve,pressuregauge,and6.Thevariablespeedcontrolisbestsuitedtoadriverwhich

fusibleplugcanbethrottled.

3.Dampenthepulsationsofareciprocatingcompressor

TorF

4.Actasacompressoroutputcontrolreferencepoint

7.Thedischargepipeofanaircompressorshouldhave

5.Allowmoistureandoilparticlestosettleoutseveral

6.Allowfurtherheatingoftheairbeforegoingtotheusedipsorbendsinittotrapthemoistureoutoftheline.

a.1,2,5,6TorF

b.1,3,4,5

c.1,2,3,68.Adiabaticcompressionispreferablebecauseofthelesser

d.2,3,4,5amountofpowerrequiredtocarryoutthecompression.

Section4Lecture6Try:7TorF

1.Twogeneraltypesordesignsofdynamicaircompressors9.Twosystemsfrequentlyusedtounloadreciprocatingair

are:compressorsistohavethe

suctionorinletorhavetheinletvalveheld

a.Rotaryandreciprocating

b.Single-stageandmultistage

c.Axialflowandcentrifugal10.Ifthereisashut-offvalvebetweentheaftercoolerandthe

d.Slidingvaneandinternalgearreceiver,theaftercoolermust

alsobefittedwitha.(twowords)

2.Barreltypecasingsincentrifugalaircompressorsarefor:

Section4Lecture6Try:8

a.Storinghighpressureair

b.Pressuresbelow6900kPa1.Axialflowcompressoradvantagesaresimiliartothoseof

c.Pressuresabove6900kPacentrifugalaircompressors.Theyhaveanadded

d.Noneoftheaboveadvantageof:

1.Thedualcontrolsystemofregulatingcompressoroutputis

a.Beinglowerincostbyimplementingboth:

b.Beingashortermachine

c.Beingcorrosionanderosionfreea.Variablevolumestopandstart

d.Beingapproximately10%moreefficientb.Stop,startandconstantspeed

c.Asafetyvalveandvariablespeed

2.Acompressordrivenbyaconstantspeeddriverhasitsd.Variablevolumeandvariablespeed

outputvariedby:

2.Anactualaircompressioncurveofapressure-volume

a.Astopandstartswitchdiagramis:

b.Asolenoidvalve

c.Amercuryswitcha.Somewherebetweenadiabaticandisothermal

d.Sometypeofunloadingdeviceb.Purelyadiabatic

c.Purelyisothermal

3.Thepresenceofmoistureintheairmaylaterresultinthed.Completelyconstantpressure

compressedairpipingbeingsubjectedtowater

hammer.3.Axialflowcompressorshavetheairflowthroughthe

TorFcompressorfrominlettodischargeinaradialdirection.

4.HighintercoolertemperaturecouldbemonitoredtoTorF

automaticallyshutdown

theaircompressor.4.Thedischargepipeofanaircompressorshouldhave

TorFseveral

dipsorbendsinittotrapthemoistureoutoftheline.

5.Anaircompressorinstalledatahighaltitudewillrequirea

highercompressionratiotoTorF

producethesamedischargepressure,asacompressor

installedatsealevel.5.Effectiveintercoolingwillreduceweakeningofpartsdue

tohigh

TorFtemperatures,andreducepossibilityofcompressor

explosions.

6.Anactualaircompressioncurveiseitheradiabaticor

isothermal.TorF

TorF6.Theflowofairfromacompressormustbetosuit

load

7.Topreventsurging,theoftherequirementsandtomaintainconstantpressureinthe

compressormustsystem.

notbeallowedtofallbelowthe

___________(2words).7.Inanairdryerusingapressurevesselcontaininga

chemical

8.Compressorlubricationmaybedividedintotwomaintoabsorbthemoisture,thechemicaliscalleda

sectionslubrication

andlubrication

8.Centrifugalaircompressorsareusedforvolume

9.Inadditiontousingintercoolerscompressorsareusuallypressureapplications.

(twowords)inordertoremovetheheatof9.Thereasonsforcoolingtheairinanaircompression

compression.systemisto:

10.Theflowofairfromacompressormustbeto1.Removewatervaporandoilvaporfromtheair

suitload2.Makecylinderlubricationmoreeffective

requirementsandtomaintainconstantpressureinthe3.Decreasetheamountofpowerrequiredto

presstheair

4.Removefixedcarbonfromthevalues

Section4Lecture6Try:9

a.2and4

b.1and4

c.1,2,33.Acompressordrivenbyaconstantspeeddriverhasits

d.Noneoftheaboveoutputvariedby:

10.Internallubricationofaircompressorsrefersto:a.Astopandstartswitch

b.Asolenoidvalve

1.Thecrankcaseandcrankshaftc.Amercuryswitch

2.Cylinderwallsandpistonsd.Sometypeofunloadingdevice

3.Vanesandcasingwallsofsomecompressors

4.Impellersofacentrifugalcompressor4.Effectiveintercoolingwillreduceweakeningofpartsdue

tohigh

a.2,3temperatures,andreducepossibilityofcompressor

b.1,3,4explosions.

c.3,4

d.1,4TorF

5.Adjustableinletvanesoncentrifugalaircompressorsare

providedinordertocontrolthe

amountofairflowingtotheimpellerandthuscontrolthe

capacityoftheunit.

TorF

6.Highintercoolertemperaturecouldbemonitoredto

automaticallyshutdown

theaircompressor.

TorF

7.Variablevolumecompressorsusestepsto

controlthecompressor'soutput.

8.Whenacompressorisstoppedthecoolingwatersupply

shouldbe(2words).

9.ofacompressoriskn