Solar hot water and space heating systems constructed of commodity polymers have the potential to reduce the initial cost of solar thermal systems. However, a polymer absorber must be prevented from exceeding its maximum service temperature during stagnation. Here, the addition of a thermotropic material to the surface of the absorber is considered. The thermotropic layer provides passive overheat protection by switching from high transmittance during normal operation to high reflectance if the temperature of the absorber becomes too high. A one dimensional model of a glazed, flat-plate collector with a polymer absorber and thermotropic material is used to determine the effects of the optical properties of the thermotropic material on the optical efficiency and the stagnation temperature of a collector. A key result is identification of the reflectance in the translucent state required to provide overheat protection for potential polymer absorber materials. For example, a thermotropic material in its translucent state should have a solar-weighted reflectance greater than or equal to 52% to protect a polypropylene absorber which has a maximum service temperature of 115 °C.
Issue Section:
Research Papers
References
1.
Hudon
, K.
, Merrigan
, T.
, and Burch
, J.
, 2012
, “Low-Cost Solar Water Heating Research and Development Roadmap
,” National Renewable Energy Laboratory (NREL), Technical Report No. NREL/TP-550054793.2.
Merrigan
, T
., 2007
, “Solar Heating & Lighting: Solar Water Heating R&D
,” DOE Solar Energy Technologies Program
, Denver, CO, Apr. 17–19.3.
IEA Task 39,
2014
, “Polymeric Materials for Solar Thermal Applications, Solar Heating & Cooling Program
,” International Energy Agency (IEA), accessed Feb. 2, 2014. Available at: http://task39.iea-shc.org/4.
Kohl
, M.
, Meir
, M. G.
, Papillon
, P.
, Wallner
, G. M.
, and Saile
, S.
, 2012
, Polymeric Materials for Solar Thermal Applications
, Wiley-VCH Verlag & Co.
, Weinheim, Germany
, p. 393
.5.
Burch
, J. D.
, 2006
, “Polymer-Based Solar Thermal Systems: Past, Present and Potential Products
,” Proceedings of the 64th Annual Technical Conference & Exhibition
, Society of Plastic Engineers
, Charlotte, NC, May 7–11, pp. 7
–11
.6.
Martinopoulos
, G.
, Missirlis
, D.
, Tsilingiridis
, G.
, Yakinthos
, K.
, and Kyriakis
, N.
, 2010
, “CFD Modeling of a Polymer Solar Collector
,” Renewable Energy
, 35
(7
), pp. 1499
–1508
.10.1016/j.renene.2010.01.0047.
Tsilingiris
, P
., 2002
, “Back Absorbing Parallel Plate Polymer Absorbers in Solar Collector Design
,” Energy Convers. Manage.
, 43
(1
), pp. 135
–150
.10.1016/S0196-8904(01)00015-28.
Mintsa Do Ango
, A.
, Medale
, M.
, and Abid
, C.
, 2013
, “Optimization of the Design of a Polymer Flat Plate Solar Collector
,” Sol. Energy
, 87
, pp. 64
–75
.10.1016/j.solener.2012.10.0069.
Cristofari
, C.
, Notton
, G.
, Poggi
, P.
, and Louche
, A.
, 2002
, “Modelling and Performance of a Copolymer Solar Water Heating Collector
,” Sol. Energy
, 72
(2
), pp. 99
–112
.10.1016/S0038-092X(01)00092-510.
Siqueira
, D. A.
, Vieira
, L. G. M.
, and Damasceno
, J. J. R.
, 2011
, “Analysis and Performance of a Low-Cost Solar Heater
,” Renewable Energy
, 36
(9
), pp. 2538
–2546
.10.1016/j.renene.2011.02.01911.
Meir
, M.
, and Rekstad
, J.
, 2003
, “Der Solarnor Kunststoffkollektor–The Development of a Polymer Collector With Glazing
,” Proceedings of the Leobner Symposium Polymeric Solar Materials
, Leoben, Austria Nov. 6–7, pp. II-1
–II-8
.12.
Resch
, K.
, and Wallner
, G. M.
, 2012
, “Polymeric Materials for Solar Thermal Applications
,” Polymeric Materials for Solar Thermal Applications
, M.
Kohl
, M. G.
Meir
, P.
Papillon
, G. M.
Wallner
, and S.
Saile
, eds., Wiley-VCH Verlag & Co.
, Weinheim, Germany
, pp. 129
–134
.13.
Rhodes
, R. O.
, 2010
, “Polymer Thin-Film Design Reduces Installed Cost of Solar Water Heater
,” Proceedings of the 39th ASES national Solar Conference
, May 17–22, Phoenix
, AZ, pp. 1580
–1588
.14.
Russell
, L.
, and Guven
, H.
, 1982
, “Modeling and Analysis of an All-Plastic Flat-Plate Solar Collector
,” ASME J. Sol. Energy Eng.
, 104
(4
), pp. 333
–339
.10.1115/1.326632615.
Baer
, S. C.
, 1985
, “Thermal Control System for Solar Collector
,” U.S. Patent No. 4,528,976.16.
Harrison
, S.
, and Cruickshank
, C. A.
, 2012
, “A Review of Strategies for the Control of High Temperature Stagnation in Solar Collectors and Systems
,” Energy Procedia
, 30
, pp. 793
–804
.10.1016/j.egypro.2012.11.09017.
Thür
, A. V.
, Hintringer
, C.
, and Richtfeld
, A.
, 2013
, “Status Quo Der Entwicklungen Eines Überhitzungsgeschützten Kunststoffkollektors
,” Erneuerbare Energie, accessed June 16
, 2014
, http://www.aee.at/aee/index.php?option=com_content&view=article&id=749&Itemid=11318.
Buckley
, B. S.
, and Guldman
, T. A.
, 1983
, “Method and Apparatus for Overtemperature Control of Solar Water Heating System
,” U.S. Patent No. 4,399,807.19.
Kusyy
, O.
, and Vajen
, K.
, 2011
, “Theoretical Investigation on a Control-Based Approach to Avoid Stagnation of Solar Heating Systems
,” Proceedings of ISES Solar World Congress
, Kassel
, Germany
, Aug. 28–Sept. 2, pp. 3323
–3330
.20.
Kearney
, M.
, Davidson
, J.
, and Mantell
, S.
, 2005
, “Polymeric Absorbers for Flat-Plate Collectors: Can Venting Provide Adequate Overheat Protection?
,” ASME J. Sol. Energy Eng.
, 127
(3
), pp. 421
–424
.10.1115/1.197951821.
Mahdjuri
, F
., 1999
, “Solar Collector With Temperature Limitation Using Shape Memory Metal
,” Renewable Energy
, 16
(1
), pp. 611
–617
.10.1016/S0960-1481(98)00236-522.
Roberts
, J.
, Brandemuehl
, M.
, and Burch
, J.
, 2000
, “Overheat Protection for Solar Water Heating Systems Using Natural Convection Loops
,” Proceedings of the Solar Conference
, American Solar Energy Society
, American Institute of Architects
, Madison, WI, pp. 273
–278
.23.
Rich
, A. C.
, 1995
, “Solar Collector Venting System
,” U.S. Patent No. 5,404,867.24.
Slaman
, M.
, and Griessen
, R.
, 2009
, “Solar Collector Overheating Protection
,” Sol. Energy
, 83
(7
), pp. 982
–987
.10.1016/j.solener.2009.01.00125.
Wallner
, G. M.
, Resch
, K.
, and Hausner
, R.
, 2008
, “Property and Performance Requirements for Thermotropic Layers to Prevent Overheating in an All Polymeric Flat-Plate Collector
,” Sol. Energy Mater. Sol. Cells
, 92
(6
), pp. 614
–620
.10.1016/j.solmat.2007.12.00526.
Muehling
, O.
, Seeboth
, A.
, and Haeusler
, T.
, 2009
, “Variable Solar Control Using Thermotropic Core/Shell Particles
,” Sol. Energy Mater. Sol. Cells
, 93
(9
), pp. 1510
–1517
.10.1016/j.solmat.2009.03.02927.
Gladen
, A. C.
, Davidson
, J. H.
, and Mantell
, S. C.
, 2013
, “Selection of Thermotropic Materials for Overheat Protection of Polymer Absorbers
,” Sol. Energy
, 104
, pp. 42
–51
.10.1016/j.solener.2013.10.02628.
Gladen
, A. C.
, Mantell
, S. C.
, and Davidson
, J. H.
, 2013
, “A Parametric Numerical Study of Radiative Transfer in Thermotropic Materials
,” ASME
Paper No. HT2013-17183.10.1115/HT2013-1718329.
Resch
, K.
, Hausner
, R.
, and Wallner
, G. M.
, 2009
, “All Polymeric Flat-Plate Collector—Potential of Thermotropic Layers to Prevent Overheating
,” Proceedings of ISES World Congress 2007
, Beijing, China, Sept. 18–21, D. Y.
Goswami
and Y.
Zhao
, eds., Springer
, Berlin, Heidelberg, Germany
, Vol. I–V
, pp. 561
–565
.30.
Weber
, A.
, and Resch
, K.
, 2014
, “Thermotropic Glazings for Overheating Protection. I. Material Preselection, Formulation, and Light-Shielding Efficiency
,” J. Appl. Polymer Sci.
, 131
(4
), p. 39950.10.1002/app.3995031.
Weber
, A.
, Schmid
, A.
, and Resch
, K.
, 2014
, “Thermotropic Glazings for Overheating Protection. II. Morphology and Structure–Property Relationships
,” J. Appl. Polym. Sci.
, 131
(4
), p. 39910.10.1002/app.3991032.
Weber
, A.
, Schlögl
, S.
, and Resch
, K.
, 2013
, “Effect of Formulation and Processing Conditions on Light Shielding Efficiency of Thermotropic Systems With Fixed Domains Based on UV Curing Acrylate Resins
,” J. Appl. Polym. Sci.
, 130
(5
), pp. 3299
–3310
.10.1002/app.3957133.
Weber
, A.
, and Resch
, K.
, 2012
, “Thermotropic Glazings for Overheating Protection
,” Energy Procedia
, 30
, pp. 471
–477
.10.1016/j.egypro.2012.11.05634.
Resch
, K.
, and Wallner
, G. M.
, 2009
, “Thermotropic Layers for Flat-Plate Collectors—A Review of Various Concepts for Overheating Protection With Polymeric Materials
,” Sol. Energy Mater. Sol. Cells
, 93
(1
), pp. 119
–128
.10.1016/j.solmat.2008.09.00435.
Gladen
, A. C.
, Mantell
, S. C.
, and Davidson
, J. H.
, 2014
, “A Parametric Numerical Study of Optical Behavior of Thermotropic Materials for Solar Thermal Collectors
,” ASME J. Heat Transfer
, 136
(7
), p. 072703
.10.1115/1.402715336.
Seeboth
, A.
, Ruhmann
, R.
, and Muehling
, O.
, 2010
, “Thermotropic and Thermochromic Polymer Based Materials for Adaptive Solar Control
,” Materials
, 3
(12
), pp. 5143
–5168
.10.3390/ma312514337.
Nitz
, P.
, and Hartwig
, H.
, 2005
, “Solar Control With Thermotropic Layers
,” Sol. Energy
, 79
(6
), pp. 573
–582
.10.1016/j.solener.2004.12.00938.
Weber
, A.
, and Resch
, K.
, 2014
, “Thermotropic Systems With Fixed Domains Exhibiting Enhanced Overheating Protection Performance
,” J. Appl. Poly. Sci.
, 131
(12
), p. 40417.10.1002/app.4041739.
Brunold
, S.
, Ruesch
, F.
, and Kunic
, R.
, 2012
, “Polymeric Materials for Solar Thermal Applications
,” Polymeric Materials for Solar Thermal Applications
, M.
Kohl
, M. G.
Meir
, P.
Papillon
, G. M.
Wallner
, and S.
Saile
, eds., Wiley-VCH Verlag & Co.
, Weinheim, Germany
, pp. 319
–349
.40.
Lenel
, U. R.
, and Mudd
, P. R.
, 1984
, “A Review of Materials for Solar Heating Systems for Domestic Hot Water
,” Sol. Energy
, 32
(1
), pp. 109
–120
.10.1016/0038-092X(84)90054-941.
Duffie
, J.
, and Beckman
, W.
, 2006
, Solar Engineering of Thermal Processes
, 3rd ed., Wiley-Interscience
, Hoboken
, NJ, pp. 204
–237
.42.
Papillon
, P.
, and Wilhelms
, C.
, 2012
, “Polymeric Materials for Solar Thermal Applications
,” Polymeric Materials for Solar Thermal Applications
, M.
Kohl
, M. G.
Meir
, P.
Papillon
, G. M.
Wallner
, and S.
Saile
, eds., Wiley-VCH Verlag & Co.
, Weinheim, Germany
, pp. 29
–70
.43.
Solar Ratings & Certification Corporation (SRCC), OG-100 Certification, accessed June 17,
2014
, http://www.solar-rating.org/ratings/index.html44.
Fischer
, S.
, Druck
, H.
, Bachmann
, S.
, Streicher
, E.
, Ullmann
, J.
, and Traub
, B.
, 2012
, “Conventional Collectors, Heat Stores, and Coatings
,” Polymeric Materials for Solar Thermal Applications
, Kohl
, M.
, Meir
, M. G.
, Papillon
, P.
, Wallner
, G. M.
, and Saile
, S.
, eds., Wiley-VCH Verlag & Co.
, Weinheim, Germany
, pp. 73
–106
.45.
Duffie
, J.
, and Beckman
, W.
, 2006
, Solar Engineering of Thermal Processes
, 3rd ed., Wiley-Interscience
, Hoboken
, NJ, p. 908
.46.
Hollands
, K.
, Unny
, T.
, and Raithby
, G.
, 1976
, “Free Convective Heat Transfer Across Inclined Air Layers
,” ASME J. Heat Transfer
, 98
(2
), pp. 189
–193
.10.1115/1.345051747.
McAdams
, W. H.
, 1954
, Heat Transmission
, McGraw-Hill
, New York
.48.
Duffie
, J.
, and Beckman
, W.
, 2006
, Solar Engineering of Thermal Processes
, 3rd ed., Wiley-Interscience
, Hoboken
, NJ, pp. 139
–173
.49.
ASTM Standard G173,
2012
, Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37 Deg Tilted Surface, Vol. 14.04, Annual Book of ASTM Standards, West Conshohocken, PA.50.
Mantell
, S. C.
, and Davidson
, J. H.
, 2012
, “Polymer Durability for Solar Thermal Applications
,” Polymeric Materials for Solar Thermal Applications
, M.
Kohl
, M. G.
Meir
, P.
Papillon
, G. M.
Wallner
, and S.
Saile
, eds., Wiley-VCH Verlag & Co.
, Weinheim, Germany
, pp. 187
–210
.51.
Raman
, R.
, Mantell
, S.
, and Davidson
, J.
, 2000
, “A Review of Polymer Materials for Solar Water Heating Systems
,” ASME Trans.-Am. Soc. Mech. Eng. J. Sol. Energy Eng.
, 122
(2
), pp. 92
–100
.10.1115/1.128821452.
UL746B,
1998
, Polymeric Materials—Long Term Property Evaluations
, Underwriters Laboratories, Inc.
, Northbrook
, IL.53.
ASTM Standard D648,
2007
, Test Method for Deflection Temperature of Plastics Under Flexural Load
, Vol. 08.01
, Annual Book of ASTM Standards
, West Conshohocken, PA.Copyright © 2015 by ASME
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