BACKGROUND OF THE INVENTION
The invention related to solar heat absorber assemblies, and solar absorber assemblies which may also be used as a fence. In addition, the invention relates to low cost solar absorber assemblies that are tolerant to partial shading.
Most current solar absorbers seek to maximize heat absorbed per unit area. Two techniques are generally employed to do this: location and insulation. The technique of locating the solar absorber where it is rarely shaded and where its angle to the sun is nearly optimal, almost always results in the roof being selected as a mounting location. The drawbacks of the roof are that it is an expensive place for mounting, and that it is a difficult place to perform maintenance. In addition, most absorbers are well insulated so that the maximum amount of heat is absorbed. However, this does not necessarily result in the highest benefit/cost ratio.
Solar absorber fence systems have previously been disclosed for swimming pools. These systems use pool water as the heat transfer fluid, which is not appropriate for winter heating applications as it will freeze. In addition, these systems do not have any provisions for minimizing heat loss in parts that are shaded.
SUMMARY
The present invention aims to provide a low cost solar absorber system.
When used as a fence where a fence would be purchased if the present invention were not available, the cost of the space heat benefit from the present invention is only the incremental cost above the cost of a fence. In order to minimize the incremental cost, the system can be made of un-insulated plastic or glass. However, the shaded and cold part of the system must be isolated from the hot parts of the system in order not impair the function of the hot parts of the system. This is accomplished by not conveying air through the solar absorbers but allowing it to rise by natural convection. Hot absorbers will be cooled by circulating cooler air through a hollow top rail which will remove the heat at the top of the absorber and allow the absorber to continue to collect heat without overheating or losing an unreasonable amount of heat to the ambient air. Absorbers that are shaded may have a small section at the top that is heated by hot air moving through the top rail, but the cold air lower in the absorber will stay there as it is more dense than the hot air at the top.
The design incorporates features that reduce the tendency of hot air to flow from the top rail into a shaded and cold absorber, which would reduce the effectiveness of the un-shaded areas.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 shows a section of fence.
FIGS. 2, 3, and 4 shows cross sections of different designs for a solar absorber assembly.
FIG. 5 shows a section view of the bottom rail, absorber, and top rail.
FIGS. 6, 7, 8 and 9 show section views of the top rail and the top portion of a solar absorber.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a portion of a fence panel 10 is shown according to the present invention. It is supported by conventional posts 11 of wood, plastic, or steel set in concrete or dirt. The bottom rail 12 functions to support the solar absorbers 14 and to act as a mounting point to attach the fence panel 10 to the posts 11 with straps or brackets 13. The upper rail 15 also acts to support the solar absorbers 14 and act as a mounting point to attach the fence panel 10 to the posts 11 with straps or brackets 13. In addition, the upper rail 15 acts as a duct through which warm air can flow and be carried into a space where heat is desired. Upper rail 15 may also act as a solar absorber.
Solar energy can be absorbed in the collector via many different methods. FIG. 2, section A-A, shows a preferred embodiment where an absorber 14 is formed from plastic or glass 20 and coated on the inside with an absorber coating 21. The coating 21 must fully coat the portion of the absorber 14 that is opposite the sun (back) and may also coat the part of the absorber 14 that is closest to the sun (front). Coating the entire absorber 14, or not protecting and masking the part of the absorber 14 that is closest to the sun during the coating process may have manufacturing cost advantages.
Referring to FIG. 3, also section A-A, the absorber 14 can be made of a clear plastic or glass 20 and contain a solar absorber plate 30. Absorber plate 30 may be attached to the back of the absorber 14 using adhesive or mechanical fasteners. Plate 30 can be mounted such that an air gap exists between the back of the absorber 14 and the plate 30. The air gap may result in improved convection of hot air.
Referring to FIG. 4, also section A-A, the front of absorber 14 can be made of a clear plastic or glass 20, while the back 40 is made of dark opaque solar absorber material such as textured black plastic. The back 40 is shown un-insulated but may contain an insulation layer.
FIG. 5 shows a vertical cross section (B-B) of the lower rail 12, the solar absorber 14, and the upper rail 15. Because some absorbers 14 of the fence panel 10 may be shaded and cold, it is not desirable to move air through these sections. Therefore, lower rail 12 does not have an internal opening to allow air to flow from it and into solar absorber 14. Instead, warm air is naturally convected up solar absorber 14 and into upper rail 15 where it is moved to the space to be heated via a blower. When a portion or all of solar absorber 14 is shaded the air inside it is not heated and does not rise into upper rail 15.
Currents flowing through upper rail 15 may disturb the air in a cold solar collector 14 and cause some of the cold air to be conveyed with the warm air in top rail 15. This is not desirable since it will decrease the temperature of the air and reduce the ability of the entire system to heat a space. FIGS. 6, 7, 8 and 9 (section C-C) illustrate methods to reduce or eliminate this mixing effect. In FIG. 6, a baffle 18 is used inside the solar absorber 14 to reduce the amount of mixing. In FIG. 7, a baffle 17 is used inside the top rail 15 to reduce the amount of mixing. In FIG. 8, a constriction 23 is placed in the solar absorber 14 to reduce unintended air flow. Referring to FIG. 9, a barrier 32 is placed between the top rail 15 and solar absorber 14 to prevent the mixing of cold air from the absorber 14 into the top rail 15. In order for heat to be conducted from warm absorbers into the top rail, heat exchange fins 31, which may be made from thin aluminum, extend from inside the solar absorber 14, through the barrier 30, and into the top rail 15.
Patent Application
20100051020
