Aluminum/Copper Solar Fins
A. General Information
1.0 Product Description
- After more than a decade of research, the Sunstrip solar fin has
emerged as one of the most innovative developments in solar technology.
The fin's metallurgically-bonded aluminum completely surrounds a rhombic
copper tube waterway. The corrosion resistance of the copper combined
with the light weight and high thermal conductivity of aluminum produces
the optimal finned tube. Sunstrip solar fins are available in either
8 mm or 12 mm nominal diameter waterways.
- Sunstrip solar fins are available with highly selective AnodicCobalt
or semi-selective black paint surface finishes; 12 mm (1/2") or
8 mm (1/4") copper waterway; cut and inflated to your specified
length or coil form.
- Fin width: 143 mm (5.63")
- Waterway: 12 mm (1/2")
- nominal Area:
Fin thickness: 0.5 mm (.02")
Fin width: 143 mm (5.63")
Waterway: 8 mm (1/4")
Fin thickness: 0.5 mm (.02")
- 1.5 kg/m2 (0.31 lb/ft2)
- 1.5kg/m2 (0.31 lb/ft2)
2.0 Product Use
2.1 Product Applications:
2.2 Geographic and Climatic Limitations:
- Residential and commercial domestic water, process hot water, space
heating, pool heating
3.0 Manufacturer's Experience
- Thermo Dynamics Ltd. (TDL) is a Canadian company engaged in the
research, development, production, distribution and installation
of solar thermal
equipment. The company has been involved in the solar industry
since 1981 and operates from its head office and factory in Dartmouth,
Scotia, Canada, sister city of Halifax situated on the Atlantic
coast. The company's specialization is the glazed liquid-flat-plate
collectors with metal absorbers. TDL is a fully integrated solar
thermal company with the ability to convert raw aluminum and copper
high technology solar water heating system.
- Thermo Dynamics Ltd., as a world leader in solar technology, manufactures
and markets solar heating equipment from complete systems to basic
selective components for O.E.M.'s licensees, dealers and distributors
throughout North America, Europe, Africa, New Zealand, as well as
10 other countries around the world. 3.2 Production: 10,000 m2 per
year for the SS146/12 and SS146/8 Sunstrip solar fin. Production
capacity is more than 400,000 m2 per year.
B. Sunstrip Solar Fins
1.0 General Description:
1.1 Generic/Trade Names:
- Two strips of aluminum metallurgically bonded to a single copper
1.2 Chemical Composition:
- Sunstrip solar fins
- MICRO-FLO® for SS146/8
1.3 Physical Treatment:
- Aluminum: 1350
- Copper: 99.9% pure
1.4 Physical properties:
1.5 Mechanical Strength:
- Average weight: 1.5 kg/m2 (0.31 lb/ft2)
- High burst pressure: 6.0 MPa (870 psi) for SS146/12
- High burst pressure: 20 MPa (2900 psi) for SS146/8
- Fin is automatically tested to 250 psi for SS146/12 1100 psi for
- For Sunstrip, featuring the aluminum substrate, with a tube of
open area 50 mm2 (.078 in2), the static burst pressure is 6.0
MPa (870 psi).
More importantly, when cycled between 21 kPa (3 psi) and 690
kPa (100 psi), the fatigue life is at least 200,000 cycles. In
cycling from 10°C (50°F) and 150°C (302°F) for
60,000 cycles results in absolutely no reduction of the static
- In production, all Sunstrip material is subjected to a combined pressure
leak test during the inflation process of the tube - following the
rolling mill operation.
C. Sunstrip Production
- Sunstrip is produced by metallurgically bonding two strips of aluminum
to a single copper tube which acts as a waterway. The Sunstrip rolling
process involves four stages. First, the raw aluminum and copper are
uncoiled, second the aluminum and copper are scratch brushed, third,
the aluminum and copper are bonded together through high pressure steel
rolls, and finally, the fin is coiled.
1.2 Brushing Station
- Two 600 kg (1322 lb) coils of aluminum and one 150 kg (330 lb) of
copper tube are loaded onto uncoilers. The uncoilers have brakes which
allow tension to be maintained.
1.3 Roll Bonding
- The raw aluminum strips are scratched brushed over the entire width
to eliminate surface contaminants and expose a large amount of underlying
virgin material. The copper tube is scratch brushed on two sides, then
flattened, and then scratch brushed on the top and bottom. This ensures
that all mating surfaces between the copper and aluminum are contaminant
- The scratch brushed aluminum and flattened copper tube are guided
between two steel rolls which apply a very high pressure to the materials.
This metallurgically bonds the materials together to form a strip of
- The bonded strip exists the steel rolls and is coiled. The finished
coils can be up to 520 linear meters (1,706 ft).
2.0 Sunstrip Availability
2.1 Coil Form
2.2 Inflation Machine
- The finished Sunstrip is available in coil form up to 520 linear
meters (1,706 ft). The coils are palleted 8 high. Each coil of Sunstrip
is 75 m2 (807 ft2). The customer can uncoil and inflate fin to their
The coils of Sunstrip are loaded onto an uncoiler. The strip is automatically
fed, inflated, and cut to length. This process is used for the SS146/12
fin only. Fin lengths available up to 5 m (16 ft).
- Round-Rhombic nipple (Type L copper) for connecting SS146/12
Sunstrip fin to copper headers. This is used for G32-P solar
Round-Rhombic nipple dimensions
2.3 Sunstrip FAKIR
- The SS146/8 Sunstrip fin is used for the MICRO-FLO® absorbers.
The coils are loaded onto an uncoiler, and then fed into
the FAKIR which inflates, punches, and bends the fin into a serpentine
This process is used for the SS146/8 fin only. Absorber lengths
are available from 1 m (3.3 ft) to 4 m (13 ft).
D. Optical Performance
- Sunstrip solar fins are available in bare aluminum, highly selective
Anodic-Cobalt, and semi selective black paint surfaces.
2.0 Anodic-Cobalt selective surface
- This surface is formed by creating a thin layer of aluminum oxide
(0.5 to 1.0 um) on the surface of the Sunstrip solar fin and then embedding
cobalt in this layer. The anodizing process, which forms the layer
of aluminum oxide, is a process used world wide to protect and prevent
it from weathering.
2.3 Spectral Properties
- The cobalt deposited in the aluminum oxide layer gives the surface
the characteristic black/green/purple colour.
- The Anodic-Cobalt selective surface has excellent spectral properties.
Testing at the University of Waterloo, Ontario, Canada yielded the
following results: absorptivity a = 92% emissivity e = 15% 2.4 Durability
The Anodic-Cobalt surface is very durable particularly at high temperatures.
- The Anodic-Cobalt surface can be applied to solar fins as long as
2.75 m (9 ft).
3.0 Semi-selective black paint
- The semi selective black paint is applied in a atomizing spraying
3.2 Spectral Properties
- The painted surface is flat black in colour.
- The spectral properties of the semi-selective black painted surface
are: absorptivity a = 94% emissivity e = 28%
- The black painted surface is very durable especially in humid conditions
- The black paint surface can be applied to solar fins as long as 5
m (16 ft).
E. Thermal and Hydraulic Performance
1.1 Fin efficiency
- Good thermal performance due to good metallurgical bonding and high
conductivity of aluminum and copper.
2.0 Hydraulic performance
- Good metallurgical bonding, highly conductive metals, and superior
surface treatments contribute to the high fin efficiency of Sunstrip
Solar Fins. Graph below shows fin efficiency versus fin width.
- Graph indicates the pressure drop through Sunstrip SS146/12 for various
lengths of fin.
F. Maintenance and Warranty
- Once installed, Sunstrip solar fins are maintenance free. Anodic-Cobalt
or painted surface should not be directly exposed to high humidity.
In collector design, suitable air flow through the collector should
be considered to maintain less than 95% relative humidity.
- Sunstrip fins are warranted for 10 years. The manufacturer may repair
or replace the fins as required at his discretion.
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