Petter Neksa - Sintef Energy Research - ULTIMI RISULTATI NELLA REFRIGERAZIONE CON R744
Technology for a better society 1
Technology for a better society 2SINTEF - A contract research organization based inTrondheim, Oslo, Bergen, Stavanger and Tromsø• SINTEF is one of the largest independent research organisations in Europe.Social perspectiveSINTEF wishes to contribute to the creation of valueand to a society in healthy sustainabledevelopment.Business conceptSINTEF sell research-based knowledge and relatedservices to Norwegian and international clients.Fundamental valuesHonesty, Generosity, Courage and UnitySINTEF has 2145 employees,1600 situated in Trondheim and 430 inOslo.SINTEF receives only 3% basic grantsNorway
Technology for a better societyCO2 applications, status transcritical• Already developed andcommercialised– Heat pump water heaters –domestic, commercial andindustrial sized– Commercial refrigerationsystems, supermarkets– Beverage coolers– Ice cream chest freezers– Water chillers for moderateclimates, air conditioning andindustrial– Transport refrigeration (bus, train)• Already developed – not yetcommercialised– Mobile air conditioning systems• Under development– Mobile heat pumps– Transport refrigeration systems(containers, truck, marine)• Under development, contd– Residential heat pumps (space heatingand reversible)– Vending machines for combined hotand cold beverages– Combined heating and cooling of non-residential and residential buildings– Heat pumps for space heating andcombined space and water heating– Heat pump dryers of residential andcommercial size, e.g. laundryapplications– Rankine power cycles for utilisation oflow temperature surplus heat• Early development– Residential air-conditioning systems– Water chillers for hot climates, airconditioning and industrial– Industrial refrigeration and heat pumps
Technology for a better societyCommercial refrigerationLargest refrigerant GHG emissions of the refrigeration sector, more than 40% of the CO2-eq emissions• General scepticism toCO2– pressure– efficiency• However– Reduced pumpingpower LT– Retrofit R22• Rolfsmann 1995?High pressurecompressorCondenserIntermediatepressurevesselLow pressurecompressorNH evaporatorCO condenserCO liquidseparatorBrine cooler.322CO AS SECONDARY REFRIGERANT2CondenserNH compressorCO compressorBrine cooler.32EvaporatorsLow pressurerecieverCascadecoolerCO IN LOW TEMPERATURE CASCADE STAGE2High pressurecompressorGasIntermediatepressurevesselLow pressurecompressorBrine cooler.recieverLow pressureEvaporatorscoolerTWO STAGE CO SYSTEM.2CO2 as heat transfer fluid CO2 transcritical /(subcritical)CO2 in low temp cascade stage• Good arguments forCO2 LT stage– No pump– Reduced swept vol– Standard pressurelevel• And– Very efficientcompression• Norild 1993• Why not all-CO2?• Benefits– One refrigerant– Small dimensions– Less costly?• Status– Several supermarketchains andmanufacturers hasdecided for CO2
Technology for a better societyCO2 is ideally for heat recovery concepts inmoderate and colder climates (Kroppanmarka)Energy WellAccumulationTanks Floor HeatingDCVIIDCV IECVLTEvaporatorHeat pump modeGascooler/condenser IIGascooler/Condenser IMTNormal CoolingFreezingHP-CompressorsLP-Com-pressorsEVGaskjøler FHDCV IIIHPVT LTT MTP MP HP MP LT EVT GCIT GCIIT GCIIIE HPCE LPCE PumpE FansMPVLPVCO2 refrigeration system superior to HFC systems in moderate and cold climates
Technology for a better societyStatus CO2 commercial,centralised systemField test system in Belluno, Italy 1999Centralised systemNominal cooling capacity 11 kWMedium temperature (-10oC)Heat rejected to liquid loopDry cooler on the roofPreliminary COP 2.4 at 30oC amb• More than 1500supermarkets in Europewith transcritical CO2• 10 kW to 1 MW• Systems have beeninstalled also outsideEurope• What about hot climates?– Too low efficiency with CO2or ….?
Technology for a better society 7Typical efficiency at varying condenser/gas coolerair inlet temperatureMore than 90% of operationCOP is importantLess than 10% of operationCapacity is importantCondenser/gas cooler air inlet temperatureCOPR-744R-404A
Technology for a better societyOne possible way:Transcritical R744 refrigeration cycleUsing a two-phase ejector for expansion work recovery and thecorresponding pressure-specific enthalpy diagram
Technology for a better societyMore efficient components, a key for improved efficiencyJoint development project between SINTEF and OE18-90m3/h R744 compressor technische DatenHöhe x Breite x Länge [mm] 500 x 440 x 830Gewicht [kg] 286Volumenstrom [m³/h] 18 - 90Hubraum [cm³] 380Max. el. Leistungsaufnahme [kW] 100Drehzahl [min-1] 800 – 4 000Frequenzbereich [Hz] 53 - 267
Technology for a better society1500 rpmdischarge pressure: 80 barsuperheat at the compressor inlet: 10 K18-90m3/h R744 compressor [%]
Technology for a better society 1255606570758085500 1000 1500 2000 2500 3000 3500OverallEfficiency[%]Revolution [rpm]75bar90bar100bar18-90m3/h R744 compressor Overall efficiency at varying speed, p0=35 bara
Technology for a better societyR744 Compressor and ComponentTest Facility @ SINTEF
Technology for a better societyConclusions14We need to reduceand GHGemissions• CO2 systems has beendeveloped andcommercialised for a lot ofapplications• Development of moreefficient components andwork recovery concepts willenable competitiveperformance also at hotambient conditions• CO2 will together with theother natural refrigerantsgive a long term solution tothe refrigerant transition
Technology for a better society 15Thank you for your attention &Questions are welcome!Petter.Neksa@sintef.noThis publication forms a part of the SINTEF – NTNU CREATIVproject, performed under the strategic Norwegianresearch program RENERGI (195182/S60). The CREATIV isfinancially supported by the Research Council of Norwayand several industry partners
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