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APPLICATIONGUIDELINE

practical application of refrigerantsr600a and r290in small hermetic systems

www.secop.com setting the standard

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1.REFRIGERANTS

RefrigerantsR600a–isobutaneandR290–propanearepossiblereplacementsforotherre-frigerantswhichheavilyimpactontheenvironment,insmallhermeticsystemssuchasfactorymadehouseholdandcommercialrefrigeratorsandfreezers.TheserefrigerantshavezeroozonedepletionpotentialODPandaneglectibleglobalwarmingpotentialGWP.Furthermoretheyarepetrolgasesfromnaturalsources.TherefrigerantR600ahasbeenusedinthepastinrefrigeratorsuptothe40'es,andhastodayawideuseindomesticrefrigeratorsandfreezersagain,inEurope,wheremostrefrigeratorsaremanufacturedusingR600aasrefrigerant.IsobutaneR600aisawellsuitedrefrigerantforhouseholdapplication,withgoodenergyeffi-ciency,butwithverydifferentcharacteristicsinseveralpoints,whichimpliesthedesignistobemadeoradopted.TherefrigerantR290hasbeeninuseinrefrigerationplantsinthepast,andisstillusedinsomeindustrialplants.IndomesticheatpumpsandairconditionersR290hasbeenusedinGermanyandSwedenforsomeyears,however,withdifferentlevelofsuccess.BecauseoftheavailabilityofisobutaneandpropaneallovertheworldtheyhavebeendiscussedwidelyforCFC,H-CFCandHFCreplacement.IsobutaneR600aandPropaneR290arepossiblerefrigerantsfortheseapplications,withgoodenergyefficiency,butspecialcaremustbetakeninregardstoflammability.

ThepropertiesofR600aandR290differfromotherrefrigerantscommonlyusedinsmallher-meticsystems,asshownintable1.Thisleadstoadifferentdesignofdetailsinmanycases.

Table 1: Refrigerant data comparison

Refrigerant R 290 R 600a R 134a R 404A R 22 R 12

Name Propane Isobutane 1,1,1,2-Tetra-

flouroethane

MixtureR 125

R 143a R 134a

Chloro-difluoro-methane

Dichloro-difluoro-methane

Formula C3H8 CH-(CH3) 3 CF3-CH2F 44/ 52/ 4 CHF2Cl CF2Cl2

Critical temperaturein °C 96.7 135 101 72.5 96.1 112

Molecular weightin kg/kmol 44.1 58.1 102 97.6 86.5 120.9

Normal boiling pointin °C -42.1 -11.6 -26.5 -45.8 -40.8 -29.8

Pressure (absolute)at -25°C in bar 2.03 0.58 1.07 2.50 2.01 1.24

Liquid densityat -25 °C in kg/l 0.56 0.60 1.37 1.24 1.36 1.47

Vapour densityat to -25/+32 °C in kg/m3 3.6 1.3 4.4 10.0 7.0 6.0

Volumetric capacity at -25/45/32 °C in kJ/m3 1164 373 725 1334 1244 727

Enthalpy of vaporisationat -25 °C in kJ/kg 406 376 216 186 223 163

Pressure (absolute)at +20 °C in bar 8.4 3.0 5.7 11.0 9.1 5.7

3

1.1Pressure R 600a

1.2Capacity R 600a

ThefirstremarkablylargedifferencebetwenR600aandR134aorR12,isfoundinthepressurelevel,whichismuchlower,e.g.at-25°Cevaporationroughly55%ofR134aor45%ofR12.Inconnectionwiththis,thenormalboilingpointisat15Kresp.18Khigher.Thisleadstooperatingpressuresbeingmuchlowerthanpreviouslybefore.Evaporatorsofhouseholdrefrigeratorswillthusoperatebelownormalatmosphericpressure.

Figure 1: Vapour pressure of different refrigerants versus temperature

Thelowpressurelevelisconnectedtoarelativelyhighcriticaltemperature.Thisgivesagoodcoolingcapacityevenathighcondensingtemperature.

R600ahasroughly50%ofR12or55%ofR134avolumetriccapacityat55°Ccondensingtem-perature,asseeninfigure2.Becauseofthisthenecessarycompressorsweptvolumewillbeupto2timesthesweptvolumeusedforR12.

Thevolumetriccoolingcapacityisavaluecalculatedfromsuctiongasdensityandenthalpydif-ferenceofevaporation.Thecompressorcapacitycharacteristics,intermsofcapacityoverevapo-ratingtemperature,areclosetothoseoftheotherrefrigerants,asshowninfigure3.

4

Figure 2: Volumetric capacity of R 600a and R 134a, relative to R 12, over evaporation tempera-ture, at 55 °C condensing and 32 °C suction gas temperature

Figure 3: Cooling capacity versus evaporating temperature with different refrigerants

5

1.3Pressure R290

1.4Capacity R290

AdifferencebetweenR290andR134aisinthepressurelevel,whichisclosertoR22andR404A,e.g.at-25°Cevaporationthepressureisroughly190%ofR134a,81%ofR404A,350%ofR600aoralmostexactlythatofR22.InconnectionwiththisthenormalboilingpointisclosetoR22also.EvaporatorswillthushavetobedesignedsimilarasforR22orR404A.

Figure 4: Vapour pressure of different refrigerants versus temperature

ThepressurelevelandcriticaltemperaturearealmostthesameasR22.However,thedischargetemperatureismuchlower.Thisgivestheopportunitytoworkathigherpressureratios,whichmeanslowerevaporatingtemperatures,orathighersuctiongastemperatures.

R290hasroughly90%ofR22or150%ofR134avolumetriccapacityat45°Ccondensingtem-perature,asseeninfigure5.BecauseofthisthenecessarycompressorsweptvolumeisclosetoR22also,and10%to20%largerthanforR404A.Thevolumetriccapacityisapprox.2.5to3timesthatofR600a.ThusthechoiceforeitherR290orR600awillleadtodifferencesinsystemdesignbecauseofdifferentnecessaryvolumeflowsneededforthesamerefrigeration.

Thevolumetriccoolingcapacityisavaluecalculatedfromsuctiongasdensityandenthalpydif-ferenceofevaporation.

6

Figure 5: Volumetric capacity of R 290, R 134a, R 404A and R 600a, relative to R 22, over evapo-ration temperature, at 45 °C condensing and 32 °C suction gas temperature, no subcooling

IfR600aorR290wouldbecharged intoanunchangedrefrigerationsystem,chargeamountcountedingramswouldbemuchlower.However,calculatedincm³,thechargewouldberoughlythesameliquidvolumeinthesystem.Thisgiveschargesofapprox.40-45%ofR22,R12,R134aorR404Achargeingrams,accordingtothedatafromtable1,whichalsocorrespondswithempiricalvalues.Maximumchargeaccordingtosafetyregulationsis150gforhouseholdandcommercialrefriger-atedappliancesandsimilarapplications,whichcorrespondstoapprox.360gofusualrefriger-ants.AdditionallyexperiencehasshownahighersensitivityofthesystemstochargedeviationsforR600a.Especiallyunderchargingtendstogivehigherenergyconsumption.Thismeansthatcharg-ingaccuracymustimprove,incm³andevenmoreingrams.Onchargesofapprox.20g,whicharefoundonsmalllarderrefrigerators,accuracymustbewithin1g.

Specification forhydrocarbon refrigerants likeR600aandR290 isnot found in internationalstandards.SomedataisenclosedintheGermanstandardDIN8960of1998,whichisanextendedversionofISO916.Thepurityoftherefrigerantmustbejudgedfromthechemicalandstabilityside,forcompressorandsystemlifetime,andfromthethermodynamicsideregardingrefrigera-tionsystembehaviourandcontrollability.

ThespecificationinDIN8960isageneralsafetyhydrocarbonsrefrigerantspecification,adoptedfromotherrefrigerantscriteriacatalogueandcoverspropane, isobutane,normalbutane,andothers.Somepointscanpossiblybeacceptedalittlelessnarrowforspecificrefrigerantsandimpuritiescombinationsafterextensiveevaluation.

Forthetimebeingnorefrigerantqualityaccordingtoanofficialstandardisonthemarket.Thespecificationsofpossiblequalitiesmustbecheckedwiththesupplierindetails.

1.5Refrigerant charge

1.6Purity

7

LiquifiedpetrolgasLPGforfuelapplicationsortechnicalgrade95%purityisnotsufficientforhermeticrefrigeration.Water,sulfurandreactivecompoundscontentsmustbeonalowerlevelthanguaranteedforthoseproducts.Technicalgrade99.5%,alsocalled2.5,iswidelyused.

Table 2: Specification of R 600a and R 290 according to DIN 8960 - 1998

Specification UnitRefrigerant content 1 ≥ 99.5 %bymassOrganic impurities 2 ≤ 0.5 %bymass1,3-Butadiene 3 ≤ 5 ppmbymassNormal Hexane ≤ 50 ppmbymassBenzene 4 ≤ 1 ppmpersubstanceSulfur ≤ 2 ppmbymassTemperature glide of evap. ≤ 0.5 K(at5to97%destill.)Non condensable gases ≤ 1.5 %vol.ofvapourphaseWater 5 ≤ 25 ppmbymassAcid content ≤ 0.02 mgKOH/gNeutralizationEvaporation residue ≤ 50 ppmbymassParticles/solids no Visualcheck

1)ThiscontentisnotexplicitlystatedinDIN8960.Onlytheimpuritiesarelistedandlimited. Themaincontentistherestupto100%. FromthermodynamiccalculationanisomercontentofR600normalButaneupto5%in R600aisobutaneisnotcriticalandstilldoesnotexceedthetemperatureglidecriteria andhasonlyverylowimpactonpressure,lessthan0.2Ktemperatureatevaporation.2)Fromcompressorpointofviewacontentuptoapprox.1%ofbutaneinR290or1%of propaneinR600aisacceptable.3)Thisisamaximumvalueforeverysinglesubstanceofthemultipleunsaturatedhydrocarbons.4)Thisisamaximumvalueforeverysinglearomaticcompound.5)Thisisapreliminaryvalue,tobereviewedwithgrowingexperience

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2.MATERIALS

RefrigerantR600a ismainlyusedwithmineral compressor oils, somaterial compatibility isalmostidenticaltoR12situationfromoilside.Useofalkylbenzenesorpolyolesteroilisalsopossible.RefrigerantR290isusedwithpolyolesteroilincompressors,somaterialcompatibilityisalmostidenticaltoR134aorR404Asituationfromoilside.R600aandR290arechemicallyinactiveinrefrigerationcircuits,sonospecificproblemsshouldoccurthere.Solubilitywiththeoilisgood.Directmaterialcompatibilityislessproblematic.Onsomerubbers,plasticsandespeciallychlo-rinatedplasticshowever,problemshavebeenobserved,butthesematerialsarenormallynotpresentinsmallhermeticsystems.Somematerials,onwhichproblemshavebeenreportedbydifferenttesters,arelistedinthetable3.Criticalmaterialstestingmustbeperformedforthespecifieduse.

Table 3: Material compatibility

Material CompatibleButylicrubber NoNaturalrubber NoPolyethylene DependsonconditionsPP NoPVC NoPVDF NoEPDM NoCSM No

Fordomesticandcommercialrefrigeratorsthecommondesiccantisamolecularsieve,azeo-lithe.ForR290amaterialwith3Åporesisrecommended,likeforR134aandR404A,e.g.UOPXH7,XH9orXH11,Grace594,CECASiliporiteH3R.PencildriersforR134acanbeusedwithoutchangesnormally.BurstpressuredemandsofIEC/ENresp.UL60335havetobecompliedwith.SeealsonoteCN.86.A.Ifhardcoredriersaretobeused,pleaseaskthemanufacturerforcompatibilitytoR600aorR290.DanfosstypeDCLEdrierscanbeused.

2.1Driers

9

3.FLAMMABILITyANDSAFETy

ThemaindisadvantagediscussedinconnectionwiththeuseofR600aandR290istheriskinflammability.Thereforecarefulhandlingandsafetyprecautionsareessential.

Table 4: Flammability of isobutane and propane

R 600a R 290Lowerexplosionlimit(LEL) 1.8% ca.38g/m3 1.7% ca.37g/m3

Upperexplosionlimit(UEL) 8.5% ca.203g/m3 9.5% ca.177g/m3

Minimumignitiontemperature 494°C 470°C

Duetoawideconcentrationrangeofflammability,safetyprecautionsarenecessary,ontheap-plianceitselfandinthemanufacturingfactory.Theriskassessmentsbehindthesetwosituationsarequitedifferent.Themaincommonstartingpointisthataccidentsmusthavetwoessentialpreconditions.Oneistheflammablemixtureofgasandairandtheotheristheignitionsourceofacertainenergylevelortemperature.Thesetwomustbepresenttogetherforcombustions,sostepstoavoidthiscombinationmustbetaken.

Figure 6: Yellow warning labels

compressorsforR600aandR290haveinternalprotectorsandPTCstartersorspecialrelays,bothpreventingsparksfromcomingoutnearthecompressor,asitcannotbeguaranteedtoholdsurroundingairbelowLELincaseofleaksclosetothecompressor.

Theyareequippedwithayellowlabelwarningforflammablegas,likeshowninfigure6.

10

3.1Appliance

For safety testing of household refrigerators and similar applications international standardshavebeenestablished.Therulesare included in the latestversions (edition4, resp.amend-mendstoedition3)of • IEC/EN60335-2-24forhouseholdrefrigeratorsandfreezers • IEC/EN60335-2-89forcommercialrefrigeratedappliances • IEC/EN60335-2-34formotorcompressorsandforNorthAmerica • UL60335-2-24andUL250forhouseholdrefrigeratorsandfreezers • UL471AmendmentSBforcommercialrefrigeratedappliances • UL60335-2-34formotorcompressorswhicharethenormalelectricalsafetystandards.Approvalsforrefrigeratedappliancesusinghydrocarbonsasrefrigerantsareaccordingtotheproceduresofthesestandardssince1994,inEurope.Themethodologyisbasedonthefollowingshortdescription.Otherapplicationsmusttakedifferentnationalstandardsandlegislationintoaccount,e.g.EN378,DIN7003,BS4344,SN253130,whichcanhavedifferentdemands.• Allelectricalelementsswitchingduringnormaloperationareconsideredpossible ignitionsources.Thisincludesthermostat,doorcontactsforlighting,on/offandother switches,likesuperfrost,compressorrelays,externalklixonandotheroverloadorsafety switches,defrosttimersandsoon.• Allrefrigerantcontainingpartsareconsideredpossiblerefrigerantsourcesthroughleaks. Thisincludesevaporators,condensers,doorheaters,tubingsandthecompressor.• Maximumrefrigerantchargeissettobe150gformostofthesestandards,pleasesee thespecificstandardforreference.Bykeepingthechargetomax.20%oflowerexplo- sionlevelLEL,whichisapprox.8g/m³,forastandardkitchen,ignitionriskisverylow, evenifrefrigerantdistributionincaseofleakageisunevenforsometimefirst.

Themaintargetofthesafetyprecautionsistoseparateroomswithrefrigerantcontainingpartsfromroomswithswitchingelements.

Figure 7: Appliance designs variants

Infigure7threeprincipalpossibilitiesareshown

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3.2Factory

Option1hastheevaporatorandthermostat/doorswitchlocatedinthestoragevolumeboth.Thisiscriticalforflammablerefrigerantsandshouldnotbeused.Option2hastheevaporatorinsideandthethermostat/doorswitchoutsideontop.Thisnormallygivesasafesolution.Option3hasthermostat/doorswitchinside,buttheevaporatorfoamedinplacebehindtheinnerliner.Thisisapossiblesolutionusedinmanycases.ThechosenoptionmustbedesignedandproveninleakagetestsaccordingtoIEC/EN60335resp.ULdemands.

Onmanyrefrigeratororfreezerdesignsthisseparationisalreadytheexistingsituation.• Largefreestandingbottlecoolersandfreezersoftenhaveallelectricalswitchesinthetop panel• Somerefrigeratorshavetheevaporatorshiddenbehindtheliner,inthefoamnotin thecabinetspace,wherethermostatsandsoonareallowedinthiscase.

Acriticalsituationiswheneveritisnotpossibletoavoidevaporatorandthermostatorswitchesbeinginthecabinet(Option1).Inthiscasetwopossibilitiesareleft.• Thermostatsandswitchesmustbechangedtosealedversionspreventinggasfrom penetratingthemandthusreachingtheswitchingcontacts.Danfossofferselectromechani- calthermostatswithsealedswitches(077BwithenclosedbreakdeviceEBD)andelectronic thermostats(ETC)suitableforthisapplication.• Fansinsidetherefrigeratedcompartmentmustbesafeandsparkfreeevenifblocked.• Electricalconnectorsandlampholdersmustbeinaccordancewithcertainspecifications.

EveryR600aandR290appliance typemustbe testedandapprovedaccording to the IEC/ENprocedures,byanindependentinstitute,eveniftheabovecriteriamentionedisincludedinthedesign.Pleaseseethestandardfordetails.Instructionsforuseshouldcontainsomeinforma-tionsandwarningsforcarefulhandling,likenottodefrostfreezercompartmentswithknives,andforinstallinginaroomwithatleast1m³ofspaceper8gofcharge,thelattertobeseenonthetypelabel.Systemsusingrelaysorotherelectricalcomponentsnearthecompressormustmeetthespeci-fications.Theseareinclude:• Fansatthecondenserorcompressormustbesparkfreeevenwhenblockedoroverloaded. Eithertheymustbedesignedtonotneedathermalswitch,orthisswitchmustmeetIEC 60079-15.• RelaysmustmeetIEC60079-15orplacedwherealeakagecannotproduceaflam- mablemixturewithair,e.g.inasealedboxorathighaltitude.

Therefrigerantcontainingsystemandthesafetysystemdesignistobeapprovedandcontrolledregularlybylocalauthoritiesnormally.BelowthedesignprinciplesforinstallationsinGermanyaregiven.Inmanydetailsthisisbasedonregulationsforliquifiedgasinstallations.Specialitiesarefoundaroundthechargingstations,wheregasconnectorsaretobehandledfrequentlyandachargingoftheappliancesoccurs.

Thebasicprinciplesforsafetyare:• Forcedventilationtoavoidlocalaccumulationofgas.• Standardelectricalequipmentexceptfortheventilationfansandsafetysystems.• Gassensorscontinuouslymonitorpossibleleakageareaslikearoundchargingstations,with alarmanddoublingofventilationat15%to20%ofLELandwithdisconnectionofallnon explosionproofelectricsinthemonitoredareaat30%to35%ofLEL,leavingthefans runningatfullspeed.• Leakagetestsonappliancesbeforechargingtoavoidchargingofleakingsystems.• Chargingstationsdesignedforflammablerefrigerantsandconnectedtothesafetysystems.

Safetysystemdesigncanbesupportedbysuppliersofchargingstationsandgassensingequip-mentinmanycases.

ForhandlingofR600aorR290insmallcontainers,therulesarelessstrictinsomecountries.

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4.REFRIGERATIONSySTEMDESIGN

Inmanycasesoftransitionfromnonflammabletoflammablerefrigerantstheappliancecabinetmustbemodifiedforsafetyreasonsaslistedinsection3.1.Changescanalsobenecessaryforotherreasons.

Refrigerant containing systemparts according to IEC / EN 60335mustwithstand a specifiedpressurewithoutleaking.Highpressuresidemustwithstandsaturationoverpressureof70°Ctimes3.5,lowpressuresidemustwithstandsaturationoverpressureof20°Ctimes5.Thisgivesthefollowingvalues:

R 600 a R 290 aLowPressureside 25 38 baroverpressureHighPressureside 35 90 baroverpressure

NationalstandardsandULstandardsmighthavedifferentspecifications,dependingontheap-plication.

Therefrigerationsystemefficiencywillnormallynotcauseaneedforchangingtheevaporatororcondensersize,whichmeanstheoutersurfacecanbeleftthesameaswithR134a,R22orR404A.Theinsidedesignoftheevaporatorpossiblyneedssomemodification,becausetherefrigerantvolumeflowisdifferent,accordingtothecompressorsweptvolume.WithR290itisclosetoR22orR404A.WithR600acomparedtoR12orR134atherefrigerantvolumeflowincreasesby50%to100%accordingtothelargercompressorsweptvolume.Thisleadstoincreasedpressuredropintherefrigerantchannelsortubes,ifthecrossflowsectionstaysthesame.Tokeeptherefrigerantflowspeedwithintherecommendedrangeof3to5m/sitmaybeneces-sarytomakethecrossflowsectionswider.InrollbondevaporatorsforR600athiscanbedonebyeitherincreasingthechannelsystemheight,e.g.from1.6mmto2mm,orbydesigningparallelchannelsinsteadofsingleones.Aparallelchanneldesignhowevermustbedevelopedcarefullytoavoidliquidaccumulations.AluminiumrollbondevaporatorsarenormallynotusedforR290becauseofthehighdemandsonburstpressure.Specialcaremustbetakenwhendesigningtheaccumulatorinthesystem.WhenusingR22,R12,R404AorR134atherefrigerantisheavierthantheoilused,whilewithR600aandR290therefrigerantislessheavy,ascanbeseeninthedatatable1.Thiscanleadtooilaccumulationiftheaccumulatoristoolarge,especiallytoohigh,andhasaflowpathwhichdoesnotguaranteeemptyingsufficientlyduringstartupphaseofthesystem.EvaporatordesignhintscanbefoundinnoteCN.82.A

4.1Heat exchangers

13

ForR600aexperienceandtheoreticalmodellingsshowtheneedforaflowratealmostsimilartoR12again.Whenchangingarefrigerationsystemwithcapillary fromR12 toR134a,veryoftenthecapillaryflowrate,expressedinlitresofnitrogeneperminuteatspecificconditions,isreducedbyelongatingthecapillary,orbytakingasmallerinnerdiameter.

ForR290experienceshowstheneedforacapillaryflowratealmostsimilartoR404A.Atleastthisisagoodstartingpointforoptimization.

AswithR134aandR404AforR600aandR290thesuctionlineheatexchangerisveryimportantforsystemenergyefficiencyofR290,whichitwasnotforR22,seefigure8.ThefigureshowsincreaseofCOPwithsuperheatfromfewKupto+32°Creturngastemperature,wherearangefrom+20°Ctoapprox.+32°Cisusualforsmallhermeticsystems.ThislargeincreaseinCOPforR290iscausedbyahighvapourheatcapacity.Incombinationwiththeneedforkeepingtherefrigerantchargeclose to themaximumpossible in thesystem, thusgivingnosuperheatatevaporatoroutlet,thesuctionlineheatexchangermustbeveryefficientforpreventingairhumid-itycondensationonthesuctiontube.Inmanycasesanelongationofthesuctionlineandcapillarygivesefficiencyimprovements.Thecapillaryitselfmustbeingoodheatexchangingcontactwiththesuctionlineforaslongapartoftotallengthaspossible.

Figure 8: Theoretical COP increase of different refrigerants versus suction temperature with adiabatic compression, internal heat exchange, at -25 °C evaporation, 45 °C condensation, no subcooling before internal heat exchanger

Athighsuperheat,withgoodinternalheatexchange,thetheoreticalCOPofR290,R600aandR134aishigherthanforR22.AtverylowsuperheattheCOPofR290,R600aandR134aislowerthanforR22.TheR290behaviourissimilartoR134a,withrespecttointernalheatexchange.

14

4.3Evacuation

4.4Noise

4.5Cleanliness of components

ForR290generallythesamerulesforevacuationandprocessingarevalidasforR22,R134aorR404Asystems.Themaximumallowablecontentofnoncondensablegasesis1%.

ForR600atheevacuationprocessmustbeimprovedremarkably.At-25°Cevaporationtempera-tureR600ahasapressureof0.58bar,whileR12has1.24barandR134ahas1.07bar,whichmeansonly47%or54%,orroughlyhalf,ofpreviouslyhandledpressurevaluesarepresent.Thismeansthatnoncondensablegascontents inarefrigerationsystemwillhavedouble thenegativeeffect thanwith theother tworefrigerants,or, taken fromthat,necessarymaximumlevelfornoncondensablegasesresiduemustbehalved.Duetoamainpartofnoncondensablegasescomingfromthecompressoroil,whichtakessometimetoextractandshowstobeanef-fectnotlinearwithtime,minimumnecessaryevacuationtimeswillbemorethandouble.Workingwithsinglesideevacuationontheprocesstubeofthecompressoronly,necessaryevac-uationtimeswillraise,dependingontheappliancedesign.Changingtotwosideevacuation,onprocesstubeandasecondconnectionatthedrier,reducesnecessarytimeagain,butincreasescost.

Aleveltoohighofnoncondensablegasesincreasesenergyconsumptionbecauseofhighercon-densingtemperatureandaportionofthetransportedgasbeinginactive.Itcanadditionallyin-creaseflownoise.Ontwotemperatureonecompressorsystemsitcangiveproblemswiththecyclicdefrostingoftherefrigeratorcabinet,whereriskforiceblockformingisincreased.

WhilethecompressorstendtobelessnoisywithR600aatlowcoolingcapacity,comparedtoR134a,partlybecauseofthelowerworkingpressurelevels,someothernoiseproblemscanoccuronappliances.Thelargerrequireddisplacementcancausehighervibrationandthuscreatenoiseintheappli-ance.Theincreasedvolumeflowcangivehigherflownoiseinevaporators,especiallyattheinjec-tionpoint.Butevenifthisnoiseinmanycasesisnotincreased,itcanbeaproblem.Ifcompressornoiseisreduced,theflownoiseappearstobetheloudestpart,notcoveredbythecompressornoiseanylonger,anditisanunexpectednoise,ahiss.Additionallythehighervolumeflowcanresultinhighergaspulsationsandbythatincreaseflownoiseorevencreatevibrationsonap-plianceparts.Increasedsuctionlineheatexchangerlengthcanreduceflownoisetoo,becauseitequalizestheflowandthusstabilizesinjection.

ThespecificationsforcleanlinessaregenerallycomparabletoR134aorR404A.TheonlyofficialstandardoncleanlinessofcomponentsforrefrigerationuseistheDIN8964,whichalsoisusedinseveralcountriesoutsideGermany.Itspecifiesmaximumcontentsofsoluble,insolubleandotherresidues.ThemethodsfordeterminingsolubleandinsolublecontentsaretobemodifiedfortheactualrefrigerantR600aandR290,butinprinciplethesamelimitsareuseful.

15

5.SERVICE/REFERENCES

ServicingandrepairofR600aandR290systemsispossibleforskilledandwelltrainedserv-icetechnicians.PleaseseenoteCN.73.Cfordetails.Locallawsandregulationsmustbetakenintoaccountalso.Verycarefulhandlingisrequiredduetotheflammabilityofthegas,whichisapotentialdangerduringworkon therefrigerationsystem.Agoodventilationof theroom isnecessaryandthedischargeofthevacuumpumpmustbeleadtoopenair.TheequipmentoftheservicetechnicianmustmeettherequirementsofR600aandR290intermsofevacuationqual-ityandrefrigerantchargeaccuracy.Anelectronicscaleisrecommendedtocontrolrefrigerantchargetowithintheneededaccuracy.ConversionofaR22,R12,R502orR134asystemtoR600aorR290 isnotrecommendedbySecop,becausethesesystemsarenotapprovedforflammablerefrigerantuse,soelectricalsafetyisnotproveninaccordancewiththerelevantstandards.

CN.86.A "DriersandMolecularSievesDesiccants",DanfossCompressorsCN.82.A "EvaporatorsforRefrigerators",DanfossCompressorsCN.73.C "ServiceonHouseholdRefrigeratorsandFreezers withNewRefrigerants",DanfossCompressors

DIN8960 "Kältemittel-AnforderungenundKurzzeichen",1998DIN8964 "KreislaufteilefürKälteanlagen", BeuthVerlagGmbH,Berlin

IEC60335-2-24"Householdandsimilarelectricalappliances-Safety Part2-24:Particularrequirementsforrefrigeratingappliances, ice-creamappliancesandice-makers",2002,A1:2005(EN:2003)IEC60335-2-89"Householdandsimilarelectricalappliances-Safety Part2-89:Particularrequirementsforcommercialrefrigeratingappliances withanincorporateorremoterefrigerantcondensingunitorcompressor", 2002(EN:2002)IEC60335-1 "Householdandsimilarelectricalappliances-Safety Part1:Genralrequirements",2001(EN:2002)IEC60079 "Electricalapparatusforexplosivegasatmospheres",2004(EN:2004)

UL60335-2-24"StandardforHouseholdandSimilarElectricalAppliances, Part2:ParticularRequirementsforRefrigeratingAppliances, Ice-CreamAppliancesandIce-Makers",2006UL60335-1 "SafetyofHouseholdandSimilarAppliances, Part1:GeneralRequirements",2006UL471 "CommercialRefrigeratorsandFreezers",2006,SupplementSB,2008UL250 "HouseholdRefrigeratorsandFreezers",2000

5.1References

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OURJOURNEySOFAR

www.secop.com

1958StartupproductionofPWcompressors.

1972IntroductionFRcompressors.

1993StartofproductionwithnaturalrefrigerantR600a(Isobutane)

ProductionfacilityinCrnomelj,Sloveniafounded.

2008ProductionfacilityinWuqing,Chinafounded.

1970IntroductionofSCcompressors.Thebirthofastandardsettingplatforminthelightcommercialmarket.

1990IntroductionNLcompressors.

2002ProductionfacilityinZlateMoravce,Slovakiafounded.

2010IntroductionSLV-CNK.2andSLV-CLK.2variablespeedcompressors.IntroductionBD1.4FMicrocompressor.

1956ProductionfacilityandheadquartersinFlens-burg,Germanyfounded

1999StartofproductionwithnaturalrefrigerantR290(Propane).

OURIDENTITyAtSecopwearecommittedtoourindustryandaregenuinelypassionateaboutthedifferenceweareabletomakeforourcustomers.Weunderstandtheirbusinessandobjectivesandthechallengesoftoday'sworldofrefrigerationandcoolingsystems.Weworkinastraightforwardway,beingopen,directandhonestbecausewewanttomakethingsclearandeasy.Ourpeoplearecommittedtoincreasingvalueforourcustomersandconstantlystriveforbetterperformance,knowingthatourownprogressionandsuccessisdependentontheirs.

1977IntroductionTLandBDcompressors.

1992IntroductionPLcompressors.

2005IntroductionGScompressors.