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Solar Thermal Systems:Solar Heating R&DNational Renewable Energy LaboratorySandia National LaboratoriesU.S. Department of EnergySolar Energy Technologies
Presentation Outline Description of solar thermal R&D activities in:– Low-cost passive solar hot water systems Polymer integral collector-storage (PICS) systems– Low-cost active solar systems Cold-climate solar water heating systems Combined heating and cooling (CHC) systemsU.S. Department of EnergySolar Energy Technologies
Solar Thermal Systems Participants National Laboratories– National Renewable Energy Laboratory– Sandia National Laboratories Industry–––––FAFCO (California)Davis Energy Group / SunEarth (California)DuPont Canada Inc. (Ontario)SRP (Arizona)Energy Laboratories Inc. (Florida) Universities– University of Minnesota– University of Colorado– University of Central Florida
Solar Thermal Systems R&D GoalsNear-Term (2006): Mild-climate solar water heating systems thatdeliver energy at 0.04 - 0.06/kWhMid-Term (2010): Cold-climate solar water heating systems thatdeliver energy at 0.05 - 0.06/kWhLong-Term (2015-2020): Solar space heating and cooling systems thatdeliver energy at 0.04 - 0.05/kWhU.S. Department of EnergySolar Energy Technologies
Solar Thermal Systems R&DLow-Cost PassiveSolar Thermal SystemsU.S. Department of EnergySolar Energy Technologies
Solar Water HeatingCommon System TypesPassiveActiveU.S. Department of EnergySolar Energy Technologies
Passive Solar Water HeatingIntegral Collector-Storage(ICS) SystemGasketGlazingsBoxStorage tanksInsulation
Innovative, Low-Cost Solar Water HeatersProject Goal:Cut the delivered, life-cycle energy cost of solarwater heating systems in half by the year 2005.Source: Solar Buildings Technology Program: 5-YearStrategic Plan, January 31, 1998U.S. Department of EnergySolar Energy Technologies
Innovative, Low-Cost Solar Water Heaters Hardware cost reduction Polymer technology Parts integration Installation cost reduction Lighter collectors, flexible bundled piping Integrated balance of system Marketing cost reduction New construction: SWH as standard feature or option Do-it-yourself / Home improvement storesU.S. Department of EnergySolar Energy Technologies
Innovative, Low-Cost Solar Water HeatersTechnical Challenges (Barriers): Polymer durability – the key technical challenge System performance– Overheating protection– Heat exchanger sizing and placement Building code issues– Use of plastics, e.g., flammability– Structural concerns, e.g., roof weight, wind loading Manufacturing process design– Thermoforming and rotomolding temperaturetolerances
Innovative, Low-Cost Solar Water HeatersProject Phases: Concept Generation / Exploratory Research– Identification of general system configurations whichcould conceivably reach the project’s cost goal Concept Development / Prototype Test– Development of detailed designs for promisingconcepts and construction and evaluation of prototypes Advanced Development / Field Test– Development of second-generation prototypes andconducting limited field testing and evaluation Engineering / Manufacturing Development– Construction of manufacturing facilities and evaluationof “near-final” systems in “real-world” applications
Unpressurized Integral Collector StorageImmersed heat exchangerGlazing(s)InsulationThin-walled polymervessel of waterU.S. Department of EnergySolar Energy TechnologiesSupply/Return Piping
Davis Energy Group/SunEarth DesignU.S. Department of EnergySolar Energy Technologies
Davis Energy Group/SunEarth Field TestU.S. Department of EnergySolar Energy Technologies
FAFCO Design
FAFCO Prototype
Solar Thermal Systems R&DMaterial Durability TestingU.S. Department of EnergySolar Energy Technologies
Durability ccelerated,Natural SunlightU.S. Department of EnergySolar Energy Technologies
UV-Screened Polymeric Glazing ConstructionScreening Layer (UV absorbers)Optional Bonding Layer (adhesive, etc.)Candidate Polymeric GlazingAnother Polymeric Element (e.g., absorber)U.S. Department of EnergySolar Energy Technologies
GE HP92WDB 20-mil thick PC FilmNo Korad UV screen; 8.2months Ci5000 exposureWith Korad UV screen; 10months Ci5000 exposureU.S. Department of EnergySolar Energy Technologies
Solar Thermal Systems R&DLow-Cost ActiveSolar Thermal SystemsU.S. Department of EnergySolar Energy Technologies
Geographical Limitations of ICS Systems
Residential Solar Water HeatingCommon System TypesPassiveActiveU.S. Department of EnergySolar Energy Technologies
Active Solar Water HeatingFlat Plate CollectorIndirect CirculationSolar System
Active Solar Water Heating System R&DDuPont CanadaUniversityof MinnesotaLabs andIndustryU.S. Department of EnergySolar Energy Technologies
Low-Cost Solar Water Heatersfor Cold ClimatesPolymer Flat PlateCollectorDuPont / University of Minnesota Collaboration
Polymeric Absorber andHeat Exchanger Testing Nylon 6,6HTNPolybutylenePolypropyleneTeflonCopperTensile strength testing Polyethylene PolypropyleneNew In-situ optical device for measuring scaleUniversity of Minnesota
Polymeric Absorber andHeat Exchanger TestingStrength after aging in Hot, Chlorinated H2OFor some polymers, hotchlorinated watersignificantly reducesstrength. Alternate PB formulation(with additives) shows lessdegradation Loss of strength occursvery rapidly in nylon 6,6. Exposed/Unexposed StrengthStrength after 300-1200 hrs in ORP 825 mV160C 82C0.80.60.40.20PSUPB (noadd)PB (wadd)Nylon 6,6HTNMaterials tested at U of MN in FY2003
Polymer Tube ScalingNATIVEAFTER540 Hr exposure to hard waterTeflon1 µm10 µm1 µm1 µm10 µm1 µmCopper
Polymer Tube Scaling (cont.) Calcium carbonate accumulates on all polymers tested.NATIVEAFTER540 Hr exposure to hard waterNylon 6,61 µm10 µm1 µm1 µm10 µm1 µmPB
Polymer Tube Scaling3.00HX1HX2HX3CaCO3 (g/m2)2.502.001.501.000.500.00nylon 6,6HTNPBTubePPTeflonCu Results indicate nylon 6,6 enhances scaling. Mass of scale on PP, PB, HTN, Teflon and copper tubes are similar.
Solar Thermal Systems R&DCombined Heatingand Cooling SystemsU.S. Department of EnergySolar Energy Technologies
Solar Thermal Systems R&D ApproachFeatures of polymer-based SWH systems: Year-round load:; good system utilization New materials:; lower cost Simple systems:; higher reliabilityU.S. Department of EnergySolar Energy Technologies
Solar Thermal Systems R&D ApproachCombined space heating and cooling systems Year-round load:; good system utilization New materials:; lower cost Simple systems:; higher reliabilityU.S. Department of EnergySolar Energy Technologies
Combined Solar Heating & Cooling System
TRIPLE PLAY MODELTSKYGSUN COMPUTED INTTSET, HTG/CLGTHOTTANKQSOL, HTGDHWDRAWQAUX, HTG/CLGDHWHTRQAUX, DHWTQSOL, CLGWATER MAINSU.S. Department of EnergySolar Energy TechnologiesCOLDTANK
Albuquerque, NMUnglazed Collector 126 ft2, T HX 5987Load (GJ)6CLG auxHTG auxDHW auxCLG SolarHTG SolarDHW Solar543210JANFEBMARAPRMAYJUNJULAUGSEPU.S. Department of EnergySolar Energy TechnologiesOCTNOVDEC
Albuquerque, NM125250500ft2ft2ft2Madison, WIMiami, CFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC
Combined Heating andCooling SystemsMost Favorable MarketsUnglazed Collector Space Heating &Hot Water Savings
Solar Thermal Systems R&D GoalsNear-Term (2006): Mild-climate solar water heating systems thatdeliver energy at 0.04 - 0.06/kWhMid-Term (2010): Cold-climate solar water heating systems thatdeliver energy at 0.05 - 0.06/kWhLong-Term (2015-2020): Solar space heating and cooling systems thatdeliver energy at 0.04 - 0.05/kWhU.S. Department of EnergySolar Energy Technologies
Solar Energy Technologies Innovative, Low-Cost Solar Water Heaters Project Goal: Cut the delivered, life-cycle energy cost of solar water heating systems in half by the year 2005. Source: Solar Buildings Te
