1.3_Jane_Davidson_-_Status_of_Solar_Thermal_Energy_Research_and_Technology_in_the_USA by gstec

VIEWS: 40 PAGES: 17

									Advancement of Distributed
Solar Thermal Technologies in
the U.S.
Prof. Jane Davidson
Mechanical Engineering
University of Minnesota
jhd@me.umn.edu

Contributors:
Susan Mantell & Lorraine
Francis, UMN
Jay Burch, Gary Jorgensen
& Tim Merrigan, NREL
Mike Rubio, FAFCO
Eric Lee, DEG & Harpiris
                                1
Energy
                           Market Potential
                                  100%
                                                             Residential

    Transportation                80%                        Commercial
                      Buildings
        ∼29%           ∼40%
                                  60%                  48%
           Industry
             ∼32%                 40%
                                         18%                    22%
                                  20%            11%

                                   0%
                                           H2O          Heating

   Water and space heating represent 10% of total U.S. energy
    consumption.
   75% of US households and commercial buildings are appropriate
    candidates for solar based on population density and climate.
   Cost is perceived to be a major barrier to greater
    implementation                                                         2
                                 Cost Targets
      Goal: Cost-neutral zero-energy homes (ZEH)
      in all U.S. climate zones by 2020.




                                 Solar America Initiative
                                                            3
Courtesy of Tim Merrigan, NREL
4
               U.S. R&D 1999-2009

   Low-Cost Solar Hot Water
    – Paradigm shift from metal/glass
      components to integrated systems
      manufactured with polymeric
      materials
   Building integrated systems
   PV/Thermal Systems
   Space Conditioning
    – High density storage, IEA 4224

                                         FAFCO polymer collector   5
    Low-Cost Polymer Based R&D
   Characterization of Glazings
    – Optical properties
    – Mechanical integrity
    – Durability (optical and mechanical)
   Absorbers
    – Materials & Design
   Heat Exchangers
    – Thermal and mechanical design
    – Effect of hot/chlorinated water on antioxidant diffusion
      in polyolefins
    – Growth and removal of CaCO3 “scale”


                                                                 6
                                                                         Glazing Materials
                                                                                           Equivalent Exposure in FL (y)
                                                                     0     2                        4             6              8          10




                                        90
                                                                90

         Transmittance (%)
                             Solar-Weighted Transmittance (%)
                                        85                      85
                                                                                                    Impact Modified Acrylic
                                        80



                                                                80




                                                                                                        Fiber Reinforced Polyester
                                        75




                                                                          Impact Modified Acrylic
                                                                75
                                                                          Company B; Material 1

                                                                          Company A; Material 2

                                                                          Fiber Reinforced Polyester
                                        70




                                                                70
                                                                     0
                                                                     0   500
                                                                         500             1000
                                                                                         1000              1500
                                                                                                          1500            2000
                                                                                                                          2000       2500
                                                                                                                                     2500     3000
                                                                                                                                             3000    UV Dose (MJ/m2)
                                                                                                                      2
                                                                     0     2                        Total
                                                                                                    4 UV Dose (MJ/m )
                                                                                                                6                8          10       Exposure (years)


 Optical performance is stable for UV exposure equivalent to ~6 years in Fl.
 Acrylic films are too brittle to withstand mechanical stress.
 Transmittance of ethylene tetrafluoroethylene (ETFE) fluoropolymer films
   remained stable in outdoor tests at 3 sites for 6 years and in the Ci5000
   WOM for a UV dose equivalent to 39 years.
                                                                                                                                                                        7
      Heat Exchanger Development
  Material selection for
     strength and minimum
     conductive resistance

                       Thermal Conductivity (W/m-K)
                                                                                                   Copper - 380 W/m-K
      P         t                                     0.6
                                                                                                                                                Reinforced
                                                      0.5                                                                                       Unreinforced
            D
                                                      0.4

Fully wetted, thin-                                   0.3

walled structures to                                  0.2

help compensate                                       0.1
for low thermal                                        0
                                                                                   NP (unreinf.)
                                                                  NP (25% Glass)




                                                                                                                 PFA




                                                                                                                             PPA




                                                                                                                                               PTFE

                                                                                                                                                       PVDF
                                                                                                                                   PPO
                                                                                                    PEEK

                                                                                                           PEX
                                                            FEP




                                                                                                                       PLS




                                                                                                                                         PPS
conductivity

                                                                                                                                                               8
                   Thermal Design of Immersed HX
                         Developed Design Tools for                                   Strategies to Improve Heat
                            Polymer Based ICS                                         Transfer in Storage Tanks




  100
                                                           0.25
                                       NuD=0.728RaD
                                       R2=0.942 (Eight-tube, P/D = 2.4)
                             0.188
           NuD=2.45RaD
            2
           R =0.566 (240-tube, P/D=1.5 to 3.3)
NuD




                                                                              0.25
      10                                                  NuD=0.675RaD
                                                           2
                                                          R =0.923 (Single tube)




               (Morgan, 1975)


      1                                                                                    Simple cylindrical
      1E+02      1E+03       1E+04        1E+05      1E+06        1E+07       1E+08
                                          RaD                                              baffle increases
                                                                                           discharge rates ∼ 30%
                                                                                                                   9
Polymer Durability in Potable Water
  Established a relationship between mechanical
   performance and polymer degradation
     Creep compliance (stiffness)
     Chemical Degradation (Oxidation induction time)
     Tensile Strength
                                                                      Plaques change after 1500
                                                                     Stiffness exposed to Cl water
                                                              100%
                                                                     hours in hot potable water
                                                              14
                                                              80%    Air 25°C




                                           -1
                                             )
                                                                     550 mV, 60°C
                                                              12     825 mV, 60°C




                                      creep compliance (GPa
                                                                     550 mV, 80°C
PSU: Shows good stability in an
                                               Antioxidant
                                                              60%
                                                              10     825 mV, 80°C
oxidative environment
                                                               8
PB/PP/PE (polyolefins): Rate of                               40%
                                                               6
antioxidant loss will affect life,
                                                              20%
thickness important                                            4

Nylon: Not suitable                                            2
                                                               0%
                                                               0     0         50    100       150      200
                                                                                   Polybutylene               10
                                                                             Exposure time (hours)Nylon 6,6
                                                                     Polysulfone
         Comparative Study of Scaling
 PP, PP-r, PEX, PP, PB, Nylon 6,6, HTN and Copper
    Relative scaling rates depend on water composition
    Scale forms more rapidly in distilled water than in tap water for identical
     temperatures and supersaturation
    Generally, scaling rates are comparable for polymers and Cu
    Scale is much easier to remove from PP than from Cu

                                                              100
                            Tap Water                          90




                                           Mass Removed (%)
                                                                                PP
  Distilled Water                                              80
                                                               70
                                                               60
                                                               50
                                                               40
                                                               30
                                                               20
                                                                           Cu
                50 µm               1 µm
                                                               10
                                                                0
                                                                    0.16     0.22      0.31    0.38

                                                                           Shear Stress (Pa)
Polymorphs
of CaCO3
                                                                                                      11
                     SunCache ICS




   Developed by Davis Energy Group; Commercialized by Harpiris Energy
   Impact-modified acrylic glazing; PE rotomolded tank with CU HX
   SRCC certified drain-back system
   75 units in field with oldest 6+ years old; 3% call back
   5-year warranty
   8 person-hour installation
   http://www.harpiris.com                                           12
         Thermoformed
        impact-modified
         acrylic glazing




                                      Parallel, serpentine
                                            Cu HX

  Rotationally molded
superlinear PE ICS tank




                                                        13
                  EPDM seal   http://www.harpiris.com
    FAFCO, Inc. Revolution and Hot2O
   Unglazed active drain back
    system
   Introduced at National Association
    of Homebuilders (NAHB)
    International Builders Show, 2007
   SRCC OG-300
   Everything is provided in one box
 Polymer collectors (48 ft2)
 Digital controller with animated display
 80 Feet of UV resistant polymer tubing and
  quick connect fittings
 Polymer drain back tank
 Circulation module containing two pumps
  and a heat exchanger
 Roof jacks and mounting hardware
 Easy to install tank adapter and all plumbing
  hardware

                                                                            14
                                            www.fafco.com   www.hot2o.com
Solar Electric / Solar Thermal
   SunEarth / PVT Solar Combined PV/Thermal Array




    Ambient air passes under the PV panel and a glazed,
    selective-surface collector. The heated air is used for
    space heating and hot water. http://www.pvtsolar.com/     15
New Initiatives
 High Density Storage
 Triple Play Systems to provide hot water, space heating and
  space cooling

                                 Building               Solar
                               Technologies

                  Efficiency Technologies                    PV and Solar Hot
                   & Building Integration                    Water Technologies


                                             Zero Energy
                                            Buildings Goal

                  Fuel Cell Technology &                     Combined Heat and
                  Hydrogen Infrastructure                    Power Technologies

                                 Hydrogen &           Distributed
                                  Fuel Cells            Energy

                                                                                  16
                                                          References
Burch, J. “Solar Thermal for Zero Energy Homes”, NREL 2007 Technology Status, National Renewable Energy Laboratory (NREL), jay_burch@nrel.gov
Davidson, J.H., Mantell, S.C., and Jorgensen, G., “Status of the Development of Polymeric Solar Water Heating Systems,” in Advances in Solar Energy, D.Y.
       Goswami, ed., American Solar Energy Society, vol. 15, 149-186, 2002.
Davidson, J.H., Mantell, S.C., and Francis, L.F., “Thermal and Material Characterization of Immersed Heat Exchangers for Solar Domestic Hot Water”, in
       Advances in Solar Energy, D.Y. Goswami, ed., American Solar Energy Society, vol. 17, 99-129, 2007.
Denholm, P., ”The Technical Potential of Solar Water Heating to Reduce Fossil Fuel Use and Greenhouse Gas Emissions in the United States”, March 2007
       NREL/TP 640-41157.
Liu, W., Davidson, J.H., and Kulacki, F.A., “Thermal Characterization of Prototypical ICS Systems with Immersed Heat Exchangers,” ASME J. of Solar Energy
       Engineering, 127, 1, 21-28, 2005.
Kearney, M., Davidson, J.H., and Mantell, S., “Polymeric Absorbers for Flat Plate Collectors: Can Venting Provide Adequate Overheat Protection?,” ASME J. of
       Solar Energy Engineering, 127, 3, 421-424, 2005.
Davidson, J. H., “Low-Temperature Solar Thermal Systems: An Untapped Energy Resource in the United States,” ASME J. of Solar Energy Engineering, 127,
       3, 305-306, 2005.
Freeman, A., Mantell, S.C., and Davidson, J.H., “Mechanical Performance of Polymer Tubes Intended for Use in Solar Heat Exchangers,” Solar Energy, 79,
       624-637, 2005.
Sanft, P., Francis, L., and Davidson, J.H., “Calcium Carbonate Formation on Cross-linked Polyethylene (PEX) and Polypropylene Random Copolymer (PP-r),”
       ASME J. of Solar Energy Engineering, 128, 2, 251-254, 2006.
Kulacki, F.A., Davidson, J.H., and Hebert, M., “On the Effectiveness of Baffles in Indirect Solar Storage Systems,” ASME J. of Solar Energy Engineering, 129,
       494-498, 2007.
Haltiwanger, J., and Davidson J.H., “Discharge of a Thermal Storage Tank using an Immersed Heat Exchanger with an Annular Baffle, Solar Energy, 83(2),
       193-201, 2009. On line August 2008 http://dx.doi.org/10.1016/j.solener.2008.07.017
Merrigan, Tim. Solar Heating Strategic Plan, June 22, 2007. NREL, Golden, CO 80401..
Merrigan, Tim. Report to Congress 2007, Solar Water Heating: Potential Energy Savings, Market Barriers, and Strategies for Wider Deployment. U.S. DOE,
       Forestall Bldg, Washington, D.C.
Mittelman, G., Alshare, A., and Davidson, J.H., in press, “A Model and Heat Transfer Correlation for Rooftop Integrated Photovoltaics with a Passive Air
       Cooling Channel”, Solar Energy.
Su, Yan and Davidson, J.H., “Transient Natural Convection Heat Transfer Correlations for Tube Bundles Immersed in a Thermal Storage,” ASME J. of Solar
       Energy Engineering, 129, 210-214, 2007.
Su, Y., and Davidson, J.H., “Multi-Zone Porous Medium Model of the Thermal and Fluid Processes during Discharge of an Inclined Rectangular Storage
       Vessel via an Immersed Tube Bundle,” ASME J. of Solar Energy Engineering, 129, 449-457, 2007.
Su, Y., and Davidson, J.H., “Discharge of Thermal Storage Tanks via Immersed Baffled Heat Exchangers: Numerical Model of Flow and Temperature Fields,”
       ASME J. of Solar Energy Engineering, 130, 021016-1-7, 2008.
Mittelman, G., Davidson, J.H., Mantell, S.C, and Su, Y., “Prediction of Polymer Tube Life for Solar Hot Water Systems: A Model of Antioxidant Loss,” Solar
       Energy, 82(5), 452-461, 2008.
Wade, A., Davidson, J.H., and Haltiwanger, J, in press, “What is the Best Solution to Improve Thermal Performance of Storage Tanks with Immersed Heat
       Exchangers - Baffles or a Partitioned tank?” ASME J. of Solar Energy Engineering.
Wang, Y., Davidson, J.H., and Francis, L., “Scaling in Polymer Tubes and Interpretation for Their Use in Solar Water Heating Systems,” ASME J. of Solar
       Energy Engineering, 127, 1, 3-14, 2005.
Wu, Z., Davidson, J.H., and Francis, L.F., in review, “Effect of Water Chemistry on Calcium Carbonate Deposition on Metal and Polymer Surfaces,” submitted
       to Journal of Colloid and Interface Science.
Lee, Eric. Harpiris Energy, 25205 Baronet Road, Corral de Tierra, CA 93908 eric@harpiris.com, www.harpiris.com
Rubio, Mike. FAFCO, mrubio@fafco.com
Wu, C., Mantell, S.C., and Davidson, J.H., “Polymers for Domestic Solar Hot Water: Long-term Performance of PB and Nylon 6,6 Tubing in Hot Water,” ASME
       J. of Solar Energy Engineering, 126, 1, 581-586, 2004.
Wu, Z., Francis, L.F., and Davidson, J.H., in press (online Nov. 2008), “Scale Formation on Polypropylene and Copper Tubes in Mildly Supersaturated Potable
       Water, Solar Energy. http://dx.doi.org/10.1016/j.solener 2008.10.012
                                                                                                                                                                17

								
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