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Downloaded by MONASH UNIV on April 12, 2016 | http://pubs.acs.org Publication Date: June 15, 1983 | doi: 10.1021/bk-1983-0220.ch003
Polymer Film and Laminate Technology for Low-Cost Solar Energy Collectors WILLIAM G. WILHELM Brookhaven National Laboratory, Solar and Renewables Division, Upton, NY 11973
Solar energy collector panels using polymer film and laminate technology have been developed which demonstrate low cost and high thermal performance for residential and commercial applications. This device uses common water in the absorber/heat exchanger portion of the device which is constructed with polymer film adhesively laminated to the aluminum foil as the outer surfaces. Stressed polymer films are also used for the outer window and back surface of the panel forming a high strength structural composite. Rigid polymer foam complements the design by contributing insulation and structural definition. This design has resulted in very low weight (3.5Kg/m ), potentially very low manufacturing cost (~$11/m ), and high thermal performance. The development of polymer materials for this technology will be a key to early commercial success. 2
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The potential for large reductions in capital cost for residential and commercial solar energy collectors can be realized with a design strategy that utilizes polymer films and high speed production equipment. Development work performed at Brookhaven National Laboratory (BNL) under U.S. Department of Energy (DOE) (1) contract has demonstrated that the concept can be applied to solar flat plate collector designs (Figure 1) that exhibit high thermal performance (Figure 2) for summer cooling (2) and winter space heating and hot water applications. Several collectors have been built and tested both at BNL and at the Florida Solar Energy Center with very encouraging results. The major contribution of this design towards high performance and low cost (3) 0097-6156/83/0220-0027$06.00/0 © 1983 American Chemical Society Gebelein et al.; Polymers in Solar Energy Utilization ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
Downloaded by MONASH UNIV on April 12, 2016 | http://pubs.acs.org Publication Date: June 15, 1983 | doi: 10.1021/bk-1983-0220.ch003
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POLYMERS
Figure 1.
IN
SOLAR
ENERGY
UTILIZATION
BNL l i g h t w e i g h t polymer f i l m s o l a r c o l l e c t o r p a n e l .
Gebelein et al.; Polymers in Solar Energy Utilization ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
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WILHELM
Polymer Film and Laminate Technology
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evolves from the use of high performance polymer f i l m s i n the window and absorber/heat exchanger p o r t i o n s of the s o l a r p a n e l . Present e f f o r t s i n the development of t h i s technology have i d e n t i f i e d polymer f i l m s which can meet the requirements of performance and c o s t . Of even g r e a t e r s i g n i f i c a n c e i s the p o t e n t i a l w i t h i n the i n d u s t r y f o r the c r e a t i o n of polymer f i l m s engineered s p e c i f i c a l l y f o r the design.
Downloaded by MONASH UNIV on April 12, 2016 | http://pubs.acs.org Publication Date: June 15, 1983 | doi: 10.1021/bk-1983-0220.ch003
S o l a r Absorber/Heat Exchanger P r e s e n t l y the absorber/heat exchanger i s the most unique c o n t r i b u t i o n i n the development because i t permits the use o f non-freeze-protected water to be used i n a vapor enclosed package ( F i g u r e 3 ) . In a d d i t i o n , i t allows the water to pass through the package a t atmospheric pressure w h i l e p e r m i t t i n g e f f e c t i v e heat exchange to the l i q u i d . This has been accomplished by the d e v e l opment of a channeled envelope c o n s i s t i n g of a symmetrically bonded laminate with an outer f o i l l a y e r . The f o i l i s important here because i t t r a n s f e r s dimensional s t a b i l i t y t o the polymer while p r o v i d i n g good l a t e r a l heat t r a n s f e r f o r the v a r i o u s opera t i n g c o n d i t i o n s . The polymer f i l m l a y e r i n s u r e s good c o r r o s i o n p r o t e c t i o n w h i l e improving tear r e s i s t a n c e and o v e r a l l package i n t e g r i t y . The outer f o i l surfaces f u r t h e r c o n t r i b u t e by p r o v i d ing a back surface with low o p t i c a l e m i s s i v i t y f o r low heat l o s s and a s u i t a b l e f r o n t surface f o r d e p o s i t i o n of a s o l a r s e l e c t i v e c o a t i n g . This package demonstrates economy by r e q u i r i n g a m i n i mum of m a t e r i a l (
