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TechnicalPapers33rdAnnualMeetingInternationalInstituteofAmmoniaRefrigerationMarch27–30,20112011IndustrialRefrigerationConference&HeavyEquipmentShowCaribeRoyaleOrlando,FloridaReturntoTableofContentsACKNOWLEDGEMENTThesuccessofthe33rdAnnualMeetingoftheInternationalInstituteofAmmoniaRefrigerationisduetothequalityofthetechnicalpapersinthisvolumeandthelaborofitsauthors.IIARexpressesitsdeepappreciationtotheauthors,reviewersandeditorsfortheircontributionstotheammoniarefrigerationindustry.BoardofDirectors,InternationalInstituteofAmmoniaRefrigerationABOUTTHISVOLUMEIIARTechnicalPapersaresubjectedtorigoroustechnicalpeerreview.Theviewsexpressedinthepapersinthisvolumearethoseoftheauthors,nottheInternationalInstituteofAmmoniaRefrigeration.TheyarenotofficialpositionsoftheInstituteandarenotofficiallyendorsed.InternationalInstituteofAmmoniaRefrigeration1001NorthFairfaxStreetSuite503Alexandria,VA22314+1-703-312-4200(voice)+1-703-312-0065(fax) © IIAR 2011 1AbstractOnemethodofreducingsystemchargeisthroughtheuseofsecondarycoolants.Thereareanumberofadvantagesthatcanberealizedincludingclosehumidificationcontrol,minimizationofairbornecontaminants,andeliminationofthedefrostcycle.Thispaperdemonstratesthesystemandoffersdetailsofoperation.Technical Paper #1MinimizeRefrigerantChargeUsingLiquidDesiccantDehumidificationMikeHarveyNiagaraBlowerCompanyBuffalo,NewYorkReturntoTableofContentsReturntoTableofContentsTechnical Paper #1 © IIAR 2011 3MinimizeRefrigerantChargeUsingLiquidDesiccantDehumidificationReducedchargerefrigerationsystemswhichusedesiccanttechnologycanofferadditionalbenefitssuchas:•Increasedsafety•Energyrecovery•Sanitizedair•OpportunityforLEEDcredit•HumiditycontrolIntroductionEnvironmental,regulatory,andeconomicconcernsaredrivingindustrialfacilitiestodesignrefrigerationsystemswhichutilizethesmallestrefrigerantchargepossible.Lightcommercialandcomfortconditioningsystemsalreadyhaverelativelysmallrefrigerantchargesbyusingpackagedrooftopequipmentorusingchilledwaterasasecondarycoolant.However,processairconditioningsystemapplicationsforfood-relatedplants(includingmeatandpoultryprocessing,processedfoodsproduction,andbrewing)andcoldstoragefacilitieshavetodate,primarilyuseddistributedrefrigerationsystems.Onemethodtoreducethesystemchargeisbyeliminatingrefrigerantdistributionpipingandreplacingitwiththedistributionofsecondarycoolants,whicharecooledbyalowchargecentralchillingrefrigerationsystem.Whilethistypeofsystemobviouslyhastheadvantageofloweringrefrigerantcharges,thereareseveralotherbenefitswhichcanbederived.DistributedRefrigerantSystemsDistributedrefrigerantsystems(showninfigure1)utilizethreebasicconnectedcomponentstoprovidecooling;anevaporator,acondenserandacompressor.Inordertocarrythenecessaryrefrigerantbetweenthecomponents,industrialsystemshaveextensivepipingloopsthroughouteachconditionedspacewhichareReturntoTableofContents 4 © IIAR 2011 Technical Paper #12011IIARIndustrialRefrigerationConference&HeavyEquipmentShow,Orlando,Floridaoftenoccupied.Thepipingsystemandeachofthecomponentscarryrefrigerant,sometimesinverylargevolumes.Inaddition,distributedrefrigerationsystemscanhaverelativelyhighmaintenancecostsassociatedwithrefrigerationreplenishmentandleakcontrol.Butdistributedrefrigerantsystemshavemanyadvantagessuchaslowcostforrefrigerantdistribution(pumpingpower),closeapproachtemperatureswhichresultingoodoverallsystemefficiency,andtheavailabilityofhotrefrigerantgasfordefrostcycles.Largedistributedsystemswith10,000lbsofammoniarefrigerantrequireregulatoryprogramstoaddresshealthandsafety.Concernsurroundingtheseregulatoryissueshascreatedademandfordesignswhichallowfacilitiestocarrylessrefrigerant,butdothesamework.Countlessfood-relatedfacilitiesrequireairtobedeliveredatorbelowfreezingtemperatures.Theadditionalcostsassociatedwithcoildefrostcycles,suchasadditionalrefrigerantpiping,controlsrepairandthefrequentcleaningsnecessarytominimizemicrobiological/bacteriagrowthontheevaporatorcoilscanbecomesignificant.Althoughdefrostefficienciesof20%arepossiblewithhotgas,almostonethirdoftheicemeltedwillsublimateandbereintroducedtothespace.SecondaryRefrigerantsOnecommonalternativetoreducerefrigerantchargeistheuseofaprimary/secondaryrefrigerationloop(Figure2).Withthisapproach,theprimaryrefrigerantchargeremainsintheequipmentroomandthesecondarycoolantispipedtoandfromtheprocessingroomairhandlingequipment.Thereareseveralinexpensiveandprovensecondarycoolantsavailable,includingvariousglycolsandhalidesaltsolutions.Saltsolutionshaveverygoodheattransferandviscositycharacteristicscomparedtoglycolhowever;non-metalliccomponentsarerequiredtoreducethepotentialforcorrosion.CalciumChloridemixedwithwaterisacommonsecondarycoolantduetoitslowcost,excellentheattransfercharacteristicsandalowworkingtemperaturedownto–50F.EventhoughglycolstypicallyrequiremorepumpingReturntoTableofContentsTechnical Paper #1 © IIAR 2011 5MinimizeRefrigerantChargeUsingLiquidDesiccantDehumidi