Optimized concentrating/passive tracking solar collector. Final report

Technical Report · Mon Jan 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/5170270· OSTI ID:5170270

Sterne, K E; Johnson, A L; Grotheer, R H

A concentrating solar collector having about half the material cost of other collectors with similar performance is described. The selected design is a Compound Parabolic Concentrator (CPC) which concentrates solar energy throughout the year without requiring realignment. Output is a fluid heated to 100/sup 0/C with good efficiency. The optical design of the reflector surface was optimized, yielding a 2.0:1 concentration ratio with a 60/sup 0/C acceptance angle and a low profile. Double glazing was chosen consisting of a polyester film outer glazing and an inner glazing of glass tubes around the absorbers. The selectively coated steel absorber tubes are connected in series with flexible plastic tubing. Much development effort went into the materials for the reflector subassembly. A laminate of metalized plastic film over plaster was chosen for the reflective surface. The reflector is rigidized by attaching filled epoxy header plates at each end. Aluminum side rails and an insulating back complete the structure. The finished design resulted in a material cost of $21.40 per square meter in production quantities. Performance testing of a prototype produced a 50% initial efficiency rating. This is somewhat lower than expected, and is due to materials and processes used in the prototype for the outer glazing, reflective surface and absorber coating. However, the efficiency curve drops only slightly with increasing temperature differential, showing the inherent advantage of the concentrator over flat plate collectors.

• Research Organization: Mithra Co., Irvine, CA (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: FG04-78AL04181
• OSTI ID: 5170270
• Report Number(s): DOE/AL/04181-T1
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
141000* -- Solar Collectors & Concentrators
COMPOUND PARABOLIC CONCENTRATORS
CONCENTRATING COLLECTORS
CONCENTRATION RATIO
COST
DESIGN
EFFICIENCY
EQUIPMENT
ESTERS
GLASS
GLAZING MATERIALS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PERFORMANCE
PERFORMANCE TESTING
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYESTERS
POLYMERS
SOLAR ABSORBERS
SOLAR COLLECTORS
SOLAR CONCENTRATORS
SOLAR EQUIPMENT
SOLAR REFLECTORS
SPECTRALLY SELECTIVE SURFACES
SURFACES
TESTING
THERMAL ANALYSIS
THERMAL INSULATION
TUBES