The heat pipe, heat transfer fin and solar tube shown above
form the heat absorption and transfer portion of the solar
collector. Unlike some other solar tube heat pipe designs,
Apricus solar tubes and heat pipes are not joined or fused
together. This allows the two components to move
independently, allowing for building movement and the
expansion and contraction that occurs daily in a solar
system. For more information about solar tubes
click here, heat pipes
click here.
Copper Header Pipe
The AP solar collector's header is designed to providing
excellent heat transfer and corrosion resistance while using
a simple "plug in" installation method.
The key features are as follows
| 1. |
Heat pipe ports provide simple plug in installation
while still ensuring tight contact with the heat
pipes for optimal heat transfer. Thermal heat
conduction grease is applied to the heat pipes
condenser prior to insertion to further enhance heat
transfer. Given the high temperatures that the
manifold is exposed to, the expansion of the heat
pipe condenser and "setting" of the heat conduction
paste results in the heat pipe being firmly held in
place. This ensures excellent heat transfer for the
life of the solar collector. As the heat pipe is
extremely reliable and durable, there is no need to
ever remove or replace the heat pipe, even if
changing a solar tube.
|
| 2. |
The twin header pipes are molded to match the shape
of the heat pipe ports in order to maximise contact
area. In addition, the heat pipe ports are brazed to the
twin header pipes providing a direct metallic connection. |
| 3. |
The "contoured" header pipe design produces
turbulent water flow enhancing heat transfer. |
|
4. |
The header pipes are brazed using Ag45CuZn, lead
free brazing rods, which are suitable for potable water
and provide a strong, quality joint. |
|
5. |
Available in rear port or end port inlet/outlet
configuration. |
|
6. |
8mm ID copper temperatures sensor ports at both the
inlet and outlet which are brazed directly to the header
pipe for accurate temperature measurements. |
Glass Wool Insulation
Glass wool is a very popular insulation material, used
throughout the world in many high temperature insulation
applications. Glass wool is also non-flammable, and so an
excellent choice for a high temperature solar thermal solar
collector. One key advantage of glass wool is that it can be
molded into any shape. Via a process similar to baking a
cake, the glass wool is "cooked" at high temperatures in a
mold to form a spongy brick which matches the shape of the
header and solar tubes. Below is a cutaway view of the top
and bottom layers of glass wool (header not shown).
Glass wool is:
- An excellent insulator K = 0.043W/mK
- Non-flammable (can withstand temperatures up to 300oC
/ 572oF)
- Made from 90% recycled glass
- Very Lightweight (~70kg/m3
density - 4.36p/ft3)
Manifold Casing
The manifold casing serves two main purposes, protecting the
header and glass wool insulation from the elements, and
aesthetics. Protection from the elements and long term
corrosion resistance is achieved via the use of UV
stabilized plastic powder coated aluminum. The powder
coating is available in a matt black, dark brown, or silver
finish. (Image below of casing lid shows the three color
options)
Mounting Frame
The AP solar collector can be installed on most roof
surfaces, and a full range of roof angles. A standard frame
is provided with all collectors, and additional frame kits
are available to suit most common installations. The various
frame components can also be used to install on most other
non-standard surfaces. Please
click here to download a
(397kb) pdf of frame assembly diagrams.
The frames are designed to withstand winds of up to 180km/h
/ 112mph, however attachment points must also be strong
enough to withstand significant pull forces that will occur
during strong winds.
Standard Frame
For flush installation on a pitched roof, the standard
mounting frame is used. The front tracks are secured to a
tiled roof using the supplied attachment straps. For
corrugated iron roofs or asphalt shingles roofs, the front
track can be screwed directly into the roof purlins. Rubber
pads are available for corrugated iron roofs to prevent
direct contact between the roof and stainless steel frame.
Low Pitched Roof Frame
If the roof pitch is insufficient, a low pitched
roof frame can be used to raise the collector angle by 9-27o.
Roof tracks are attached to the roof in the same way as the
standard frame front tracks. The rear legs can be cut short
to reduce the angle of the frame. The rear x brace is
required to ensure lateral rigidity of the frame, and can be
cut to length according to front track spacing and chosen
angle.
 |
|
|
| 1. |
Bottom Track* |
| 2. |
Front Track* |
| 3. |
Roof Track |
| 4. |
Rear Leg |
| 5. |
Rear X Brace |
|
*
Standard Frame Components |
Note:
1) 22 and 30 tube
frames have three sets of legs and two sets of
rear X braces.
|
|
Flat Roof Frame
For installations on a flat surface, an adjustable
angled flat roof frame is used. This frame comprises the
standard mounting frame with the addition of rear legs, feet
and several braces. See the picture below. The rear legs are
adjustable height, provided adjustment from angles of 30-50o.
Lower angles (5-23o) for use on low angle roof
installations can be achieved by cutting the rear legs short
to suit.
 |
|
|
| 1. |
Bottom Track* |
| 2. |
Round Foot |
| 3. |
Front Track* |
| 4. |
Front Brace |
| 5. |
Diagonal Brace |
| 6. |
Adjustable Height Leg |
| 7. |
Rear X Brace |
|
* Standard Frame
Components |
Note:
1) 22 and 30 tube frames have three sets of
legs and two sets of rear X braces.
2) Feet must to bolted to the ground/roof
|
|
All frame components, including bolts, washers and nuts are
made from 304 stainless steel. The angled mounting frame is
already partly assembled, making installation very quick and
easy. All required nuts & bolts (apart from foot anchoring
bolts) are already in place, and a 14mm spanner is provided
to tighten bolts.
Unfortunately the frame cannot be made to suit every
installation perfectly, so sometimes small modifications are
required. This is easy to complete and usually requires
drilling extra holes or reducing the rear leg length.
Top of page
Reflective Panel
Unlike some evacuated tube solar collectors, AP solar
collectors do not use a reflective panel.
Why??
Reflective panels are designed to increase absorption area
for a given number of solar tubes by reflecting light onto
the underside of the tubes. In order to achieve this the
tubes are spaced as far as 90mm apart to allow light to fall
on the panel. Theoretically this will increase heat output
for a given number of solar tubes, and under test conditions
with a new, shiny, reflective panel, it does. But what
happens when the panel gets dirty and develops a layer of
oxidation after a year or two of use? The reflective
properties are greatly reduced, thus the performance
benefits of the reflective panel are diminished. When the
benefits of the reflective panel drop the resultant actual
absorber area is only that of the 12 or 16 solar tubes; for
a 16 tube 47/1500 solar tube system, that is only 0.84m2
of absorber area, and an absorber to gross area ratio
of 0.29. (When gross surface area = 2.9m2).
In order to ensure stable heat output for the full life of
the solar collector, AP solar collectors do not rely on
reflective panels for performance, instead our 58mm solar
tubes are spaced close together to minimize light loss
between the tubes. Apart from ensuring an excellent absorber
to gross area ratio (0.55), this spacing, combined with the
curved absorber area of the tubes, results in
IAM values that ensure high heat output from mid morning
right through until late afternoon.
Reflective panels also add a great amount of wind resistance
to the solar collector, particularly for solar collectors
installed at a raised angle such as on a flat roof. With
high speed winds, the use of a reflective panel can result
in structural load issues for the frame and roof attachment
points. Without a reflective panel installed the solar
collector provides much less wind resistance as the tubes
are round and the wind can pass between them.
