US20090194095A1

US20090194095A1 - Solar air-heating system

Info

Publication number: US20090194095A1
Application number: US12/344,224
Authority: US
Inventors: Joel Fairstein
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-18
Filing date: 2008-12-25
Publication date: 2009-08-06

Abstract

A roof-mounted solar air-heating system containing a solar absorber with at least one air manifold integrated structurally with the solar absorber to effect improved heat transfer efficiency and airspeed. The improved airspeed in combination with integrated air entrance and exit tubes improves solar-heated air displacement and temperature de-stratification in buildings without need for tie-in to other ventilation equipment.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PPA application No. 61/021,984, filed Jan. 18, 2008 by the present inventor, which is incorporated by reference.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention generally relates to solar heating systems, specifically where heating is effected by air medium.
2. Prior Art
Glossary of Terms:
Air plenum: An air containment structure.
Building: Man-made roofed structure encompassing an open or closed space.
Collimated: Alignment of air movement in one consistent direction.
Communicating: Allowing air flow.
De-stratify: Unify air temperature at different heights in a space.
Manifold: Structure that divides and distributes airflow.
Solar absorber: Solid material that collects solar radiation and retains it as heat.
Solar heat collector: Structure that collects solar radiation and retains it as heat.
Streamlined: Quality of smooth or flowing contour designed for decreasing air resistance.
Ventilation equipment: Equipment for displacing air from one location to other locations.
Previously, advances in solar absorber materials have ensured efficient capture and retention of solar heat. These materials, usually termed “solar selective,” are commercially available for inclusion in solar-heating systems. When such material is heated by the sun, the heat can then be conducted to an air medium. Typically in this field, a stream of air impinging on the solar absorber, also variously termed “solar heat collector,” solar absorber plate,” “solar collector,” or “solar absorbing means,” carries heat to a building interior.
Previous art in this field has neglected efficiency in transfer of heat from solar absorber to the air medium. Air flow is forced through narrow openings and around sharp angles without the broadening and streamlining effect of air manifolds. This results in pressure loss, less heat exchanged, and lower heat output. Also neglected in prior art is effective air displacement into central areas of building spaces.
In U.S. Pat. No. 6,807,963 (2004) to Niedermeyer, air impinges on a solar heat collector without benefit of air manifolds. As a result, less air comes in contact with the solar heat collector during a given time interval, which reduces heat transfer efficiency. Furthermore, the solar heat collector will retain a greater amount of heat relative to ambient air temperature, an imbalance which encourages radiative heat losses. Also, the device lacks a clear means of displacing heated air into a building.
In U.S. Pat. No. 6,494,200 (2002) to Rylewski, air impinges on the solar absorber, termed “panel heated by solar radiation” without the benefit of air manifolds, which reduces heat transfer efficiency. Airflow is restricted to one side of the panel heated by solar radiation, further reducing heat transfer efficiency.
In U.S. Pat. No. 6,018,123 (2000) to Takada, Fukai, Mimura, Mori, and Shiomi, air impinges on a solar heat collector without benefit of air manifolds, which reduces heat transfer efficiency. Airflow is restricted to one side of the solar heat collector, further reducing heat transfer efficiency. Also, the suggested installation of the apparatus substantially flat on a low-sloping roof does not optimally expose the solar heat collector to low-angled winter sun.
In U.S. Pat. No. 5,596,981 (1997) to Soucy, air impinges on a solar absorber plate without benefit of air manifolds, which reduces heat transfer efficiency. Airflow is restricted to one side of the solar absorber plate, further reducing heat transfer efficiency.
In U.S. Pat. No. 5,657,745 (1997) to Damminger, airflow is restricted to one side of a solar heat absorption sheet. Also, the device lacks a clear means of displacing heated air to a building.
In U.S. Pat. No. 5,692,491 (1996) to Christensen, Kutscher, and Gawlik, an unglazed transpired solar collector lacks a clear means of displacing heated air to a building. Also, lack of glazing encourages conductive heat loss.
In U.S. Pat. No. 5,081,982 (1992) to MacKenzie, air movement depends on heat convection rather than active air impeller force. This limits the amount of air, in a given interval, impinging on a solar absorbing means. As a result, the solar absorbing means will retain a greater amount of heat relative to ambient air temperature, an imbalance which encourages radiative heat losses. Furthermore, lacking an air impeller, heated air from this device will convect up a wall rather than out into an occupied space. Also, the recommended placement of the device in a window blocks significant natural sunlight and heat.

SUMMARY OF THE INVENTION

My invention is an improved solar air-heating system that significantly increases heat conversion efficiency and air displacement into buildings. The invention encourages air temperature destratification within building interiors without need for tie-in to additional ventilation equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the invention.

FIG. 2 is a perspective view of a building roof that has been prepared for installation of the invention.

FIG. 3 is a perspective view of the invention installed on a building roof.

FIG. 4 is a perspective view of a housing assembly.

FIG. 5 is a perspective view of an insulated air plenum.

FIG. 6 is a perspective view of a solar absorber assembly.

FIG. 7 is a juxtaposed view of a glazing and a retainer frame.

FIG. 8 is a detail view of the retainer frame.

FIG. 9 is a juxtaposed view of main component assemblies.

FIG. 10 is a perspective view of nested component assemblies.

FIG. 11 is a perspective view of an air inlet and an air outlet.

FIG. 12 is a partial cross-sectional view of incoming air flow.

FIG. 13 is a partial cross-sectional view of outgoing air flow.

FIG. 14 is a perspective view showing operation of the installed invention.

FIG. 15 is a cross-sectional diagram of air de-stratification within a building.

FIG. 16 is a perspective view of an installed alternate embodiment of a solar air-heating system that utilizes an attached reflector.

DETAILED DESCRIPTION

FIG. 1—Preferred Embodiment

We will first look at one means of installation of a preferred embodiment of the invention in order to gain an overview. Reference is made to FIG. 1, which shows the system in its complete, uninstalled condition. Attached underneath nested assembly 27 a are sheet- metal collars 51 and 56, to which are mounted, respectively, air inlet tube 50 and air outlet tube 55. Electric fan 52 is mounted underneath air inlet tube 50.
In FIG. 2, we see a prepared building roof 21 and cut through it are holes 22 and 23 along a line 21E that is drawn parallel to the earth's equator. Roof curb 24 is attached to roof 21 over hole 22; in similar fashion, roof curb 25 is attached to building roof 21 over hole 23. For the purpose of explanation, a roof curb is a commercially available weather-tight equipment support with openings at the top and bottom that allow air communication through a building roof between the building's interior and roof-mounted ventilation equipment. Tack strips 24A and 25A are wooden rims integral with roof curbs 24 and 25 and can accept nail or screw fasteners for secure attachment of ventilation equipment.
Turning to FIG. 3, the invention is shown attached to roof curbs 24 and 25 so that air inlet tube 50 and air outlet tube 55 each penetrates roof 21 through respective holes 22 and 23. Below roof 21, electric fan 52 is attached to the underside of tube 50 so that when switched on, it will impel air in direction 59. We will describe operational detail of the invention later in this section.
Now, we will turn to the construction of the invention. In FIG. 4, housing 28, consisting of frame 29 and back piece 30 is shown. Frame 29 is a sheet-metal box open at its front and rear vertical planes and flanged at its rear edges 90 degrees inward to provide a flat mounting surface for back piece 30. Back piece 30 consists of flat sheet metal and is fastened to the rear side of frame 29. Six- inch diameter openings 29A and 29B are cut through the bottom side 29C of frame 29, respectively near each long end of bottom side 29C.
FIG. 5 shows air plenum 31, essentially a box open at its front vertical plane and constructed of foil-lined polyisocyanurate foam boards 32, 33, 34, 35, and 36, which are glued together with construction adhesive. Air plenum 31 is slightly smaller in all its outer dimensions than housing 28 shown in FIG. 4. In FIG. 5, openings 33A and 33B are cut vertically through foam board 33 so that when air plenum 31 is nested within the housing 28 shown in FIG. 4, openings 33A and 33B shown in FIG. 5 will align with openings 29A and 29B of FIG. 4.
FIG. 6 shows absorber assembly 37, which by general description is a solar absorber with structurally-integrated manifolds. This arrangement comprises a principle design feature of the present invention.
Solar absorber 39 consists of a rectangle of solar-selective foil and stands vertically on a long edge. Flat absorber plates 38A and 38B, each of substantially stiffer metal than solar absorber 39, are rectangular structural side extensions for absorber assembly 37, stand vertically on a short edge, and are substantially solar-selective.
Four sets of four, air vanes 42, 43, 44, and 45 are cut from thin aluminum flashing material in four graduated lengths, attached in order of length as matched pairs on opposite fields of metal plates 38A and 38B, each pair's bottom edges spaced at short, regular distances, and top edges spreading in an open-leaf profile. The attachment means can be with threaded rods, with welds, with high-temperature adhesives, or by molded integration with flat absorber plates 38A and 39B.
Absorber assembly 37 is integrated by fastening two rails 41 of right-angle metal stock along the rear top and bottom edges of metal plate 38A, solar absorber 39, and metal plate 38B. The finished outer dimensions of absorber assembly 37 must be slightly smaller than the corresponding dimensions of the opening in air plenum 31, shown in FIG. 5.
FIG. 7 illustrates a transparent, rectangular sheet of glazing 47 consisting of shatter-proof and heat-resistant material. Retainer 48 is an open rectangular frame, consisting of right-angle metal stock, of slightly greater outer dimensions than those of glazing 47, but with slightly smaller outer dimensions than the corresponding dimensions of the void enclosed by housing 28 in FIG. 4.
FIG. 8 is a detail view of joining at the corners, specifically the right bottom corner, of retainer 48.
In FIG. 9, housing 28, air plenum 31, absorber assembly 37, glazing 47, and retainer 48 are shown juxtaposed prior to final assembly. The assembly proceeds in the following manner: air plenum 31 slides in direction 27B into housing 28 until it stops against back piece 30. Absorber assembly 37 slides in direction 27B—into air plenum 31 until it stops against foam board 36. Glazing 47 slides in direction 27B into housing 28 until it stops against the open edges of nested air plenum 31. Retainer 48 then slides in direction 27B inside housing 28 and stops against glazing 47.
When fastened to housing 28, retainer 48 holds nested assembly 27A together as shown in FIG. 10. Nested assembly 27A is now by general description an air plenum containing a solar absorber with integrated manifolds.
Turning to FIG. 11, air inlet 49 is shown comprised of a sheet-metal tube 50 attached to a corresponding opening 51A cut through a flat and substantially square sheet-metal collar 51. Air outlet 54 is comprised of a sheet-metal tube 55 attached to a corresponding opening 56A cut through a flat and substantially square sheet-metal collar 56. The lengths of tubes 50 and 55 should be cut to different lengths, if necessary to keep their bottom openings at substantially the same elevation when installed on a building.
In FIG. 12, air inlet 49 is shown attached under the left side of nested assembly 27A (shown without glazing for clarity) so their openings correspond, to form an air entrance passage to the void within nested assembly 27A. When electricity is supplied to electric fan 52, air passes through tube 50 and then follows manifold air races 42, 43, 44, and 45 and impinges on both sides of absorber 39 while flowing in the general direction indicated by arrow 59. This action encourages efficient heat transfer from absorber 39 to the air. The streamlined curvature of manifold air races 42, 43, 44, and 45 shown reduces air turbulence to minimize air pressure loss and maintain airspeed through the invention. The multiplicity of manifold air races 42, 43, 44, and 45 serves to distribute air broadly across absorber 39 to encourage efficient heat transfer.
In FIG. 13, air outlet 54 is attached under the right side of nested assembly 27A (shown without glazing for clarity) so their openings correspond, to form an air exit passage. Air passing through nested assembly 27A and across both sides of absorber 39 is received by manifold air races 42, 43, 44, and 45 in the general direction indicated by arrow 61. This action further encourages efficient heat transfer from absorber 39 to the air impinging on it. The streamlined curvature of manifold air races 42, 43, 44, and 45 reduces air turbulence to minimize air pressure loss and maintain airspeed through the invention. The multiplicity of manifold air races 42, 43, 44, and 45 shown also serves to receive air broadly from across absorber 39 to encourage efficient heat transfer.
We now turn to the detailed operation of the installed invention as illustrated in the preferred embodiment. In FIG. 14, absorber 39 inside nested assembly 27A absorbs solar radiation from sun 62 as indicated by arrow 62A. Electric fan 52 passes air from under roof 21 into the path shown by arrows 59, 60, and 61, first through air inlet tube 50, then across absorber 39 within nested assembly 27A, through air outlet tube 55 where the air movement is collimated, and finally under roof 21. Due to efficient heat transfer and maintenance of air speed earlier described, heat is displaced 16 to 20 feet below roof 21 as indicated by arrow 61.
Electricity to electric fan 52 can be controlled externally by common electrical switches or thermostats, so that during periods when heat is not desired, active airflow will stop. In this inactive state, location of tubes 50 and 55 at a similar height in this embodiment discourages convective heat circulation through the invention.
The operational description above demonstrates the main purpose of the present invention, that is, to provide solar air heat with improved efficiency and displacement into buildings. The invention also provides air temperature de-stratification in buildings, according to the FIG. 15 diagram.
It is well known that heat naturally rises via convection from lower air strata in buildings and then collects near the ceiling in an upper stratum. This presents two problems in colder weather for buildings and occupants: first, heat leaves the occupied lower air stratum, and second, heat is lost convectively through the roof. FIG. 15 illustrates a single-story building 20 seen in cross-section. Within building 20, we see an occupied lower air stratum 20A with occupants 75, a middle air stratum 20B, and a higher air stratum 20C. Naturally-occurring heat convection is indicated by arrows 65, 66, and 67. The invention is shown supported and attached to roof 21 by roof curbs 24 and 25. When fan 52 is turned on, warm air that has collected in air stratum 20C is siphoned upward into fan 52 as indicated by arrows 68 and 69. This air then flows in general path 70 within nested assembly 27A, is collimated by tube 55, and exits the invention. The collimated air flows downward, as indicated by arrow 71, through air strata 20C and 20B and finally dissipates into lower air stratum 20A. Warmer air from stratum 20C is therefore de-stratified through the action of panel 27. A resulting air turbulence as indicated by arrow 72 helps to mix air strata 20A, 20B, and 20C to accomplish further de-stratification. The invention can also be installed in multiples to achieve greater heat and destratification within buildings.
FIG. 16 shows an alternate embodiment of the device wherein a flat rectangular reflector 72, constructed of rigid material with a highly reflective upper surface, is attached to panel 27 horizontally forward so that a long rear edge of reflector 72 attaches above collars 51 and 56. Vertical supports 73 and 74 are attached under the front edge of reflector 72 and to roof 21. The orientation of reflector 72 at a substantially right angle to absorber 39 augments direct solar radiation 59A from sun 59 with reflected solar radiation as indicated by arrows 59B and 59C. This reflective augmentation results in increased heat output from the invention.
From the description above, several advantages of the present invention become evident:
(a) The integration of manifold air races with the solar absorber reduces air turbulence and pressure loss, which increases heat transfer to the air medium.
(b) The open-leaf arrangement of manifold air races in the airflow path distributes air broadly across the solar absorber, which effectively increases heat transfer to the air medium.
(c) Airflow is enabled simultaneously across both sides of the solar absorber, which increases heat transfer to the air medium.
(d) The increased airspeed in the invention displaces solar-heated air far into a building interior.
(e) The presence of downward-extending air tubes in combination with increased airspeed encourages building air temperature de-stratification.
(f) The downward-extending air entrance and exit tubes terminate at substantially the same height, which discourages airflow from passive air convection when the fan is off and heat is not desired.
(g) Separate ductwork for the invention and tie-in with a building's existing ventilation system is obviated because of robust exit airspeed and collimation.
(h) The system is easily installed on low-rise building roofs.
(i) System components are nested in final assembly which saves manufacturing time and expense.
(j) The invention as described in the embodiments will withstand harsh outdoor conditions.
(k) Mirror surfaces are easily attached to the invention to augment solar exposure and thereby increase heat output.
The specific embodiments described herein should not be construed to:
(a) exclude use of other materials than those mentioned in the construction of the present invention,
(b) limit the position, shape, or number of manifold vanes,
(c) restrict the application of the invention, modified or unmodified, to building structures only,
(d) restrict the invention's purpose to that of providing heat to building occupants,
(e) limit the installation of the invention, modified or unmodified, to building roofs only,
(f) limit the shape and orientation of attached reflective augmenting surfaces.
(g) limit solar reception to one side only of the invention. For example, an embodiment of the invention with a double-side solar absorber: one side receives solar energy directly, and its opposite side simultaneously receives solar energy from reflective surfaces fixed near the invention.
(h) Limit the invention to a standalone form factor. For example the invention could be split into interconnected components, or the invention's separated components could be combined functionally with other devices.

Claims

1. An improved solar air-heating system comprising:

a. an oblong air plenum with at least one transparent side that permits solar radiation,

b. an entrance opening and an exit opening to the air plenum such that an air pathway is established substantially through the length of the plenum,

c. a substantially flat absorber that heats when exposed to solar radiation and is positioned within the air plenum so that the field of the absorber stands vertically and divides the air pathway along its length,

d. an air manifold intercepting the air pathway,

whereby air, when forced through the air plenum will impinge upon a broader area of the solar absorber field and thereby speed heat conversion from the solar absorber, when it is heated by solar radiation, to the air.

2. The improved solar air-heating system of claim 1, further including an air exit tube that communicates with and extends downward from the air plenum exit opening, such that when the air plenum is installed above a building, the air exit tube will penetrate a corresponding and necessary pre-cut hole through the building's roof, and allow communication between the air plenum and the building's interior,

whereby any airflow forced through the air plenum is collimated along the length of the air exit tube and thereby carries heat farther into the building interior.

3. The improved solar air-heating system of claim 1, further including an air entrance and an air exit tube each communicating with and extending downward from the corresponding air plenum's entrance and exit openings, such that when the air plenum is installed above a building, said tubes will penetrate corresponding and necessary pre-cut holes through the building's roof, allowing communication between the air plenum and the building's interior, so that when airflow is forced at a substantial speed through the air plenum, air from the air stratum that exists in the building's interior just under its roof enters the air entrance tube, flows through the air plenum, exits through the air exit tube, and penetrates substantially below said air stratum,

whereby air temperature within the building will become destratified partially or completely.

4. An improved solar air-heating system comprising:

a. an air plenum of substantially oblong box shape, that permits sunlight through a trans-parent sheet that forms one of the plenum's two long vertical sides,

b. an entrance opening and an exit opening to the air plenum, both substantially round holes cut through the bottom side and at opposite ends of the air plenum, such that an air pathway is established through the length of the air plenum,

c. a substantially flat absorber that heats when exposed to solar radiation and is positioned within the air plenum so that the field of the absorber sits vertically and divides the air pathway along its length,

d. an air manifold in a position intercepting the air pathway just after the air entrance opening, consisting of a series of oblong vanes, each vane with its field perpendicular to the absorber and attached to it lengthwise, the vanes placed with their bottom short edges parallel and at substantially equal intervals across the air plenum's said openings, the vanes' parallel top edges fanning from their bottom edge origin across the height of the absorber field, where the vanes span the perpendicular distance between the absorber and one or other of the plenum's long vertical sides, so that absorber, vanes, and one or both of the plenum's long vertical sides enclose manifold air passageways,

whereby each manifold will encourage airflow, when air is forced through the air plenum, across a broader area of the solar absorber field and thereby speed heat transfer from the solar absorber to the air.

5. The improved solar air-heating system of claim 4, further including an air exit tube that communicates with and extends downward from one of the air plenum openings, such that when the air plenum is deployed above a building, the air exit tube will install through a corresponding hole in the building roof and allow communication between the air plenum and the building interior,

whereby any airflow forced through the air plenum is collimated by the air exit tube,

and thereby displaces

heat farther into the building interior.

6. The improved solar air-heating system of claim 4, further including an air entrance and an air exit tube each communicating with and extending downward from the corresponding air plenum's entrance and exit openings, such that when the air plenum is installed above a building, said tubes will penetrate corresponding and necessary pre-cut holes through the building's roof, and allow communication between the air plenum and the building's interior, so that when airflow is forced at a substantial speed through the air plenum, air from the air stratum that exists in the building's interior just under its roof enters and flows through the air plenum and subsequently penetrates substantially below said air stratum,