Basic test results are given for a flat plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level

Johnson, S. M.

English

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Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19770006593 2020-03-22T12:23:12+00:00Z
by Susan M. Johnson
Lewis Research Center
Cleveland, Ohio
November 1976
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NASA TECHNICAL	 NASA TM X-73415
MEMORANDUM
(NASA—Td— Y-73415) STANDARDIZED PERFCRIIANCk	 U77-13536
Ti^STS OF COLLECTORS GF SOLAR THEBRAL EbiERGY:
AN EVACUATED FLATPLAIt COPPER COLLLCIOFc WITH
A SEIPSYTIVE FLCW DISIFsibUTIUb (NASA) 8 p	 Unclas
HC A02/AF AO t	 CSCL 101 G3/44 58273
STANDARDIZED PERFORMANCE TESTS OF COLLECTORS
OF SOLAR THERMAL ENERGY - AN EVACUATED FLAT-
PLATE COPPER COLLECTOR WITH A SERPENTINE
FLOW DISTRIBUTION
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1. Report No.
T
2, Government Accession No. 3. Recipient's Catalog No.
NASA TM X-73415
4. Title and Subtitle STANDARDIZED PERFORMANCE TESTS OF CC, Report Date
COLLECTORS OF SOLAR THERMAL ENERGY - AN
e, Performing organization CodeEVACUATED FLAT-PLATE COPPER COLLECTOR WITH A
SERPENTINE FLOW DISTRIBUTION
7. Authors) 8. Performing Organization Report No
Susan M. Johnson E-9001
10. Work Unit No.
9. Performing Organization Name and Address
Lewis Research Center 11. Contract or Grant No.
National Aeronautics and Space Administration
Cleveland, Ohio 44135 13. Type of Report and Period Covered
Technical Memorandum12. Sponsoring Agency Name and AddressNational Aeronautics and Space Administration
14. Sponsoring Agency code
Washington, D. C	 20546
15. Supplementary Notes
16. Abstract
This preliminary data report gives basic test results of a flat-plate solar collector whose
performance was determined in the NASA-Lewis solar simulator. The collector was tested
over ranges of inlet temperatures, fluxes and one coolant flow rate. 	 Collector efficiency is
correlated in terms of inlet temperature and flux level.
17, Key Words (Suggested by Author(s))
	 18. Distribution Sutemert
Evacuated solar collector
	
Unclassified - unlimited
Solar simulator
19. Security Clanif. (of this report)
	
20. Security Clanif, (of this page) 21.
	
No. C  .;,y,s
	 ^ 7:'.	 Pnce'
Unclassified	 Unclassified
For sale by the National Technical Information Service, Springfield, Virgi nia 22iu:
NASA-C-168 (Rev. 10-75)
STANDARDIZED PERFORMANCE TESTS OF COLLECTORS OF SOLAR
THERMAL ENERGY - AN EVACUATED FLAT-PLATE COPPER
COLLECTOR WITH A SERPENTINE FLOW DISTRIBUTION
Susan M. Johnson
Lewis Research Center
INTRODUCTION
An area that has been investigated by the NASA Lewis Research
Center in its efforts to aid in the utilization of alternate energy
sources is the use of solar energy for the heating and cooling of
buildings. An important part of this effort was the evaluation of
solar collectors which have the potential to be efficient, economical,
o	 and reliable.0
w	 This preliminary data report gives basic test results of a col-
lector whose performance was determined in the NASA-Lewis solar
simulator. In the interest of providing performance data on this
collector to the technical community as quickly as possible, the
basic test results reported herein are presented without evaluation.
Detailed analyses and interpretation of these results may be presented
in subsequent papers or reports by this Center. Some of the results
contained in this report may be changed as warranted by reviews and
evaluations, or by obtaining additional data on this collector.
Reference 1 describes the solar-simulator test facility, as well
as the basic test procedure.
COLLECTOR DESCRIPTION
The Solar.vak flat plate solar collector was manufactured by Solar
Systems, Inc. of Tyler, Texas. The collector is designed to be
evacuated but the particular collector tested had an internal pressure
only slightly less than atmospheric (28.5 inches of mercury). Wooden
dowels separate the 1/4 inch thick acrylic top and bottom sheets.
These two acrylic sheets form the box-like construction of the collector
with nuts and bolts holding the assembly together at the flanges.
The absorber plate is copper with a selective surface copper oxide
coating and is suspended and held in place by several 1 inch diameter
wooden dowels. The fluid flow is serpentine configuration with 3/8 inch
STAR cat. 44
2O.D. copper tubes soldered to the underside of the absorber plate.
Aluminum foil is placed on the bottom and directly behind the flow tubes
to reduce energy lost by radiation from the back of the absorber
plate. No insulation is present in the collector. A photograph of the
collector on the test stand is shown in figure 1.
COLLECTOR TEST RESULTS
Basic test results are given in Table I. Since this collector
was larger than the area of radiation provided by the solar simulator,
it was necessary to use a "shield" approach as explained in Reference 1.
This technique allows one to determine the efficiency of the entire
collector even though only a portion of it is actually exposed to
radiation. By using the analytical method outlined in Reference 1 for
a collector tested with a "shield", the results given for the flow
rate in Table I were used for a determination of the performance
correlation given in Figure 2.
In addition to the basic test performed on the collector, a series
of incident angle tests were run to help predict changes of sun in-
cidence angles thoughout the period of one solar day. Table II
lists the collector efficiency at various rotation and incident angles,
along with K..T values. One analytical method for interpreting
and using these data can be found in Reference 1.
REFERENCES
1. Simon, Frederick F.: Flat-Plate Collector Performance with a Solar
Simulator as a Basis for Collector Selection and Performance
Prediction. NASA TMX-71793, 1975.
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TABLE II. - INCIDENT ANGLE MODIFIER DATA
Tilta
angle,
deg
Rotation
angle,
deg
Incidence
angle,
deg
Efficiency KaT
57 0 0 0.820 1.0
57 50 41.5 0.816 0.995
57 70 57.5 0.769 0.938
57 80 65.2 0.720 0.878
aTilt angle - the angle between the horizontal and the
plane of the collector.
Rotation angle - the angle that is measured in relation
to the X-axis when the collector is
rotated around the Z-axis.
Incidence angle - the angle that is measured between the
beam of light and the normal to the
plane of the collector.
Z
1 . --may
-^ , 
Incidence
angle	 x Tilt.
1
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Standardized performance tests of collectors of solar thermal energy: An evacuated flatplate copper collector with a serpentine flow distribution

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