WO2013133900A2

WO2013133900A2 - Solar thermal apparatus

Info

Publication number: WO2013133900A2
Application number: PCT/US2013/000063
Authority: WO
Inventors: Donald Bennett Hilliard
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-03-09
Filing date: 2013-03-09
Publication date: 2013-09-12
Anticipated expiration: 2014-09-09
Also published as: WO2013133900A3

Description

SOLAR THERMAL APPARATUS

FIELD OF THE INVENTION

This patent application claims the benefit of US Provisional appln Ser. No. 61/634,987. The present invention is related primarily to the field of non-concentrated solar-thermal modules and associated energy conversion apparatus. More particularly, the invention discloses a solar thermal roofing module, related apparatus and methods.

BACKGROUND OF THE INVENTION

Seamed roofing modules are a prevalent means of implementing metal roofing. The term "standing seam" metal roofing refers to the methods and structures utilized in joining adjacent panels of the metal roofing system, wherein the seam is formed by a protruding lip that stands out of the plane of the panel. Such standing seams may be formed in a variety of shapes, and usually protrude outward from the roof surface, though some face inward for a flush appearance.

Over the last several decades, a large variety of structural approaches and methods have been introduced for the purpose of integrating heat exchangers with architectural roofing systems in the ongoing effort to extract useful heat from residential and commercial roofs by heat exchangers utilizing a wide variety of heat pipes, circulating heat transfer fluids (HTF), and circulating air. Barriers to adoption of such approaches have in large part resulted from the inability of such approaches to be readily incorporated into existing construction practices, existing skill sets, and existing building codes.

SUMMARY OF THE INVENTION

The present invention provides a means for field installed roofing modules, or alternatively, self- supporting ST panels, which incorporate high-efficiency solar selective absorbers in a thin film multilayer structure enabling the reliable use of preferred aluminum alloys with such absorber materials in an open-air environment wherein such absorbers provide many years of direct exposure to local weather conditions. There are herein also additionally disclosed structures and methods that allow for field-installation of highly efficient solar-thermal roof modules, or alternatively, solar- thermal panels, wherein such modules may be reliably and inexpensively installed by means of professional skill sets normally employed in the construction industry.

In the first preferred embodiments, an improved solar thermal roofing module is provided for use as a fully exposed and weather-proof roofing module, wherein such module is fully compatible as replacement for existing standing seam roofing systems, with no protective transparent cover required for reliable performance in weathering conditions.

Vapor deposited high-temperature compounds utilized in the present invention are found effective as diffusion barrier and corrosion barrier layers for protecting aluminum alloys from direct exposure to outdoor weathering conditions, without use of a transparent cover sheet that covers the absorber and protects it from such exposure. An aluminum roof panel of the preferred embodiments is coated with an under-layer of copper (preferably with thickness of 50-lOOOnm), onto which is then deposited at least two more layers of a solar selective absorber. Such multilayer structures formed over aluminum alloys is found effective in providing greatly improved corrosion resistance in application requiring directly exposed weathering conditions. Another aspect of the invention utilizes 2-phase material in multiple heat pipes of large contact area, or alternatively a closed loop reversible reaction cycle, utilizing a non-deforming thick film bonding means, so that surface roughening and phase transformations of the preferred aluminum roofing panel are largely avoided. Such greatly increased thermal contact removes non-attractive discoloration due to knurling or welding, lessens corrosion due to such surface disturbing methods, and decreases temperature cycling of the solar-thermal roofing module for higher reliability and corrosion resistance.

Therefore, an all-aluminum (bulk materials) structure for solar thermal roofing modules is herein disclosed.

In the preferred embodiment, aluminum-on-aluminum bonding methods are developed for creating an all-aluminum solar-thermal roofing module, thereby allowing single sheets of roofing material to be constructed with architectural dimensions of 5 meters and longer. Thus an objective of the present invention is to provide a standing seam roofing module having a vapor deposited absorber coating and integrated heat transfer means.

Yet another objective of the present invention is to provide a standing seam roofing module having a vapor deposited absorber coating and integrated heat transfer means, wherein the heat transfer means are joined to the absorber structure by means of a metal-to-metal seal formed by solidifying a molten metal.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means and absorber substrate are both aluminum.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means and absorber substrate are both copper.

Another objective of the present invention is to provide a standing seam roofing module having a vapor deposited absorber coating and integrated heat transfer means, wherein union of the heat transfer means to a fluid-carrying manifold is provided within a roof ridge-cap structure.

Another objective of the present invention is to provide a standing seam roofing module having a vapor deposited absorber coating and integrated heat transfer means, wherein the module has a length of greater than 2 meters, and preferably greater than 4 meters.

Another objective of the present invention is to provide a roofing module having a vapor deposited absorber coating and integrated heat transfer means, wherein the module is corrugated and a flattened heat pipe is fastened within the corrugation.

Another objective of the present invention is to provide a standing seam roofing module having a vapor deposited absorber coating and integrated heat transfer means that is formed by sputtering an absorber material onto a roof section having heat transfer means previously installed. Another objective of the presently embodied solar thermal roofing module is to provide a roofing module of sufficient aspect ration to enable covering of architectural structures without lapping.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein a region adjacent the union between the heat and absorber sheet does not contain a substantial deformation of the absorber coating due to joining procedures.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module having a metal absorber sheet and integrated metal heat transfer means, wherein the heat pipe and absorber sheet are characterized by a difference in thermal expansion coefficient of less than 2 parts per million per degrees Celsius.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means are bonded to an absorber coated sheet by means of first depositing a thin film adhesion coating on the surfaces to be bonded.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means are bonded to an absorber coated sheet by means of liquid-solid transition of a bonding metal, preferably in at temperature below 300C.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means are demountable by heat treatment, and both components readily recycled and individually replaced.

Another objective of the presently embodied solar thermal roofing module is to provide a standing seam roofing module with integrated heat transfer means, wherein the heat transfer means are field mountable and demountable by heat treatment. Another objective of the presently embodied solar thermal roofing system is to provide apparatus and methods for economical field-installation of an insulated solar-thermal metal roof system utilizing standing seam metal roofing.

Another objective of the presently embodied solar thermal roofing module is to provide an insulated metal roof system that retains high temperatures for preventing condensation within the metal roof.

Another objective of the present invention is to provide a vacuum barrier assembly (VBA) that provides operation between 0 to 150 Celsius, the VBA formed as a silicone-encapsulated planar window.

Another objective of the present invention is to provide a vacuum barrier assembly (VBA) that provides operation in temperature range of 0 to 150 Celsius, the VBA formed as a rectangular plate with organic edges that interlink to adjacent absorber plates.

Yet another objective of the present invention is to provide a construction for a self-standing solar thermal panel, wherein a solar absorbing layer is formed on substantially flat, and interlinking, absorber plates that are individually insulated from the environment and convection losses by means of flat vacuum-insulated, double-pane, borosilicate glass windows.

Yet another objective of the present invention is to provide a construction for a self-standing solar thermal panel, wherein a substantially flat solar-absorbing layer is thermally conductive to a heat transfer fluid (HTF), wherein the HTF is less than 10 centimeters from the solar absorber, and preferably less than 3 centimeters.

Yet another objective of the present invention is to provide a construction for a self-standing solar thermal panel, wherein solar-absorbing layer are formed on substantially flat, and interlinking, absorber plates that align to HTF coupling means of registering against the absorber plates back side. Other objects, advantages and novel features of the invention will become apparent from the following description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. l(a-b) is, (a) a perspective view of a standing seam roof of the first preferred embodiment, and, (b) is a vapor deposited multilayer absorber coating of the preferred embodiments.

FIG. 2(a-c) is (a) a perspective broken- view of a solar-thermal roofing module of the first preferred embodiments viewing predominantly the underside of the module, (b) is a bondable tube insert, and, (c) is a thermal contact structure.

FIG. 3(a-c) is (a) a perspective view of a heat transfer element of the preferred embodiments (b) is a schematic end-view of a solar thermal module of the preferred embodiments, and (c) is a broken sectional end view of the invention in an alternative embodiment incorporating a corrugation.

FIG. 4(a-b) is (a) a side sectional broken-view of the invention in its preferred application within a roofing system, and (b) is plan view of the invention in a preferred embodiment shown in conjunction with broken- view sections of heat transfer tube.

FIG. 5(a-d) is (a) a sectional side-view schematic of valve means allowing convective flow to ambient air, (b) a sectional side-view schematic of valve means in closed position, (c) a sectional side-view schematic of valve means providing convective flow to an application, and,(d) a perspective view of a building having a standing seam roof of the preferred embodiments.

FIG. 6(a-d) is (a) a is a schematic side-view of a heated press operation, (b) a perspective view of an unassembled vacuum barrier assembly (VB A) of the preferred embodiments, (c) a side sectional view of a metal seal gasket indicating profile shape of a metal gasket seal of the preferred embodiments, and (d) a side-sectional view of the assembled VBA without silicone encapsulating features. FIG. 7(a-c) is (a) a top plan view of an un-encapsulated VBA of the preferred embodiments (b) a close-up, side-sectional view of an edge region of the embodied VBA in unsealed stage, and (c) a close-up, side-sectional view of the embodied VBA with glass-to-metal seals in place.

FIG. 8(a-d) is (a) a top plan view of a silicone encapsulated VBA of the preferred embodiments (b) a close-up, side-sectional view of an edge region of the embodied VBA in sealed and silicone encapsulated stage, with section taken through plane (73) in FIG. 8(a), (c) a close-up, side- sectional view of an edge region of the embodied VBA in sealed and silicone encapsulated stage, with section taken through plane (72) in FIG. 8(a), and (d) a top plan view of an assembled line (77) of multiple VBA's.

FIG. 9(a-c) is (a) a bottom plan view of a solar-thermal panel section of the preferred

embodiments (b) is a side view of the solar-thermal panel section, and (c) a top plan view of the solar-thermal panel section.

FIG. 10(a-b) is (a) a close-up, end-sectional view of a seam region of the preferred embodiments utilizing VBA's of the invention with sectional view taken in the vicinity of a support member, (36) or (39), and, (b) is an end-sectional view of a seam region, taken through a plane corresponding to HTF tube axis (43), that is less magnified than in FIG. 10 (b) so as to show orientation of the seam region with HTF pipe (40) and heat transfer elements (26).

FIG. ll(a-d) is (a) is a side view of a fastening bracket (69) of the preferred embodiments (b) a perspective view of the bracket, (c) is an end-view of the bracket, and (d) is a perspective view of a conventionally roofed building supporting a solar-thermal panel module of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the first preferred embodiments, roll-formed aluminum sheets are provided in the form of a standing seam roof panel (1), characterized by a profile possessing a substantially flat cross- sectional region disposed for comprising a corresponding area of a building's roof. (23) right-hand side standing seam profile preferably shaped so as to provide complementary mating relationship with left-hand side standing seam profile (23) of an adjacent identical roofing module. As in the prior art standing seam panels, such mating profiles are preferably joined by a standing seam cap piece (29) so that the mating seam structures may be identically mirrored profiles or else be configured to mate as complementary profiles.

In the first preferred embodiments, the disclosed solar-thermal (ST) roofing panel (1) is of a "standing seam" construction. The roofing panel/module of the preferred embodiments may thus be constructed with a variety of seam constructions, depending on the architecture of a building, local weather, and aesthetic preferences. Whereas the preferred embodiments incorporate a seam structure departing from the plane of the roof in an outward direction and incorporating a substantially right angle profile in the standing seam, many possible profiles of the seam structure may be readily incorporated, and a variety of seam cross-sections and standing seam roof profiles may be selected from numerous vendors of standing seam roofing systems.

In the first preferred embodiments, the disclosed ST roofing module comprises a standing seam profile, preferably manufactured with planar dimensions appropriate for commercial and residential roofs. Accordingly, planar width of the roofing module will preferably be in the range of 12-36 inches, whereas the length will preferably be in a range of roughly 6-24 feet. It is also preferred that the gauge of metal utilized is thick enough to provide a durable roof, such that the thickness of metal used is in range of 0.015 to 0.050 inches, and most preferably the roof panel sheet has thickness in the range of 0.026 inches to 0.038 inches. Vacuum deposition of the selective absorber onto aluminum, or alternatively copper, alloys of this thickness range is preferably performed by in-line or batch-type vacuum deposition equipment, though roll-to-roll processing is also possible for the thinner gauges without departing from the scope of the present invention. Optionally, the back side of the embodied standing seam roof module is provided with insulating layer (16) attached, such layer preferably comprising a glass wool, or alternately a polyisocyanurate or appropriately rated composite board.

Metal brake and roll-forming equipment for making the standing seams are readily obtained from a variety of vendors such as Manek, Wuko, Ermaksan, Drako, Fonntai, etc. In accordance with the first preferred embodiments, a standing seam roofing panel and construction system incorporates a directly exposed and weatherable solar-thermal absorber surface (5), formed onto the roof panel front side (21), which is functionally incorporated into a field-installed metal roofing system with simultaneous coupling to a building's heat circulation.

A key component of the inventive solar-thermal roofing module is the capability to withstand direct exposure to outdoor environments without degradation. Such requirements of direct exposure are found to require that the absorber comprise a multilayer structure that simultaneously provides desirable solar selective absorption, while also having characteristics that prevent corrosion such as galvanic degradation through pinholes in the multilayer coating. It is also found that degradation processes can begin at the edge of a coated roofing module and proceed inward to effect

performance and aesthetic value of the more interior regions of the roof panel. A composite coating structure is herein found effective for providing such simultaneous requirements of selective optical performance and corrosion-resistance. A solar-thermal roofing module of the first preferred embodiments is coated on its front side with a multilayer including at least three, and more preferably at least four discernible layers each having a composition different from an adjacent layer. Such layers can be made to have abrupt interfaces, or graded interfaces. In the first preferred embodiments, the first two layers of the multilayer, deposited first, are preferably a dyad of metals, most preferably comprising a first layer of a metal (51) including at least one metal chosen from the group comprising Cr, Ti, Zr, Mn, Sn, Sb, which first layer is preferably between 10 and 100 nm. A second layer, which is alternatively the first layer if there is an alternate surface treatment of the aluminum substrate, is a layer of metal (52) that is preferably predominantly copper, or

alternatively, predominantly Cr, Mn, Ni, or Co, comprising a thickness preferably in range of 100- 2000 nanometers. This underlying metal, preferably the embodied dyad, layer is subsequently over- coated with at least two additional layers comprising at least partially reacted layers (53) (54) of metal oxides and/or metal nitrides, in FIG. 1(b). The second pair of layers, though more are readily incorporated, is preferably comprising reacted absorber layer (53), that is preferably in thickness range of 80 to 200 nanometers, and preferably comprises titanium, or alternatively, zirconium, chrome, manganese, or silicon. Other materials may also be found appropriate for this layer. The fourth embodied layer (54) is also at least a partially reacted layer, and more preferably a silicon dioxide layer having thickness in range of 80-140 nanometers.

The solar selective absorber coating (5) of the first preferred embodiments is preferably a multi- component coating of at least two layers, and most preferably at least three layers comprising a copper underlayered TiNOx .

It is also preferred that the edges of the embodied solar-thermal roofing module be encapsulated by an organic/inorganic composite material, preferably an aluminum-based paint, but alternatively an organic such as an acrylic or epoxy. Such edge coating preferably comprises a bead of material covering at least the region within one millimeter of the solar roof module's terminated (typically cut and smoothed) edges. In yet another embodiment, such protective edge bead comprises a solidified metal that is applied in a molten state.

Integral heat transfer elements (3), are bonded, preferably on the roof panel's backside, or alternatively on its front side, and exchange heat from the embodied roof panel to a separate heat storage medium, preferably a heat transfer fluid (HTF) (20) flowing through the interior of a nearby copper HTF pipe (40). The heat transfer elements (HTE) preferably comprise a flat aluminum tube comprising a sealed volume enclosing a heat transfer medium. In a first preferred embodiment the heat transfer medium comprises a two-phase evaporant so that the heat transfer element comprises a traditional convective heat pipe. In an alternative preferred embodiment, the heat transfer element efficiently transfers heat through utilization of a reversible chemical reaction wherein heat energy is absorbed along the length of this preferably linear element and expelled at the output end-structure (26) of the HTE by means of, respectively, endothermic and exothermic reactions of such a reversible reaction cycle. Any appropriated heat transfer mechanism previously reported in the prior art of heat transfer mechanics and methods may be utilized, and accordingly, the embodied linear heat transfer element may thus comprise the preferred single linear volume or it may have an interior volume that is bifurcated so as to provide a closed loop system. In an alternative embodiment, such heat transfer elements comprise open loop passageways for exchanging heat from the solar absorber to a heat storing medium by flowing liquid, super-critical media, gases, vapors, etc. In an alternative preferred embodiment the HTE's are manufactured as a cavity structure into which customers may insert heat transfer structures and media suited for a particular climate and/or application.

The preferred HTE is a conventional heat pipe and accordingly utilizes a 2-phase working medium, wherein the medium is evaporated within the heat pipe at a lower portion of the heat pipe used for removing heat from the roofing panel, and the evaporated vapor produced is consequently condensed at an upper end of the heat pipe used for providing heat to the HTF within the HTF manifold. In the case that the heat transfer element is a heat pipe, the working fluid of the heat pipe can be any suitable working medium of the prior art heat pipes, including Flutec PP2, ammonia, methylamine, pentane, cyclopentane, water, acetone, toluene, Freon, methanol ethanol, etc. Such heat pipes may alternatively be capillary pumped loop systems

The interior of the heat transfer elements (3) when acting as a heat pipe or utilizing a closed loop reaction cycle, may also be coated with a material, such as an electrodeposited silver, nickel, copper, or chrome, for providing an effective seal against out-gassing of the preferred aluminum HTE material and/or provide better thermal contact to an interior wicking medium. Alternatively the interior coating may render the HTE material compatible with previously problematic working fluids (e.g., using methanol in an aluminum heat pipe).

In the preferred embodiment, the aluminum HTE provides heat to a circulating HTF by means of the HTE output end-structure (26) having integral dove-tail-type mating thermal contact structure for mating to a complementary thermal contact structure (TCS), wherein both output end-structure and mating TCS comprise aluminum (typically an aluminum alloy) and are preferably of sufficient mass to enable proficient heat spreading, in FIG. 2(a). The TCS (27) preferably comprises an integral split-bushing with dove-tail-type female thermal contact structure disposed to mate to the HTE output end-structure, in FIG. 2(c). The mating surfaces may comprise other contact structures such as mating flat surfaces, tapered channels, tapered posts or similarly swaging surfaces. In the first preferred embodiment, the mating surfaces of TCS and HTE are channeled, and more preferably dove-tail channeled, to provide a mating structure that can be economically reproduced with a high precision. The TCS is also provided an orthogonally oriented straight bore (38) for sliding over commercially available copper tubing, typically 1 "- 4" diameter range. The straight bore of the TCS preferably comprises a clamp-able split-bushing for fast field mounting and easy alignment. It is also preferred that the mating surfaces of the HTE and TCS be factory pre- wet with a pre-wet bond-layer (37) comprising a relatively low-temperature solder, most preferably an indium-containing metal, so that the installed roof module is provided increased thermal contact to the TCS by subsequently heating the mated TCS structure to the low-temperature solder's melting point, such, as in the case of an indium pre-wet bond-layer (PWBL), the mated TCS need only be heated to around 160 degrees Celsius, which is preferably performed by localized heating of the HTE/TCS union through the roof panel (1) after assembly, or alternatively is performed under each panel as the roof is assembled. So as to increase heat coupling into the HTF provided in an HTF- circulating tube (40) there is further embodied a surface-increasing, cylindrical insert structure (41), preferably comprising copper, or alternatively aluminum or other high-conductivity material, in FIG. 2(b). The cylindrical insert structure (CIS) is inserted and positioned within the interior of the HTF tube (40) so as to be aligned within and coaxial to the subsequently positioned straight- bore surfaces of the bored TCS, in FIG. 2(b). Accordingly each set of an HTE output structure (26), the correspondingly mated TCS, and internal tube insert (41) will be aligned with these structure's lateral centers aligned to a predetermined position line (46). The embodied insert will preferably have a cylindrical aspect that is closely matched in outer diameter to the inside diameter of the copper HTF tube (40), and is also preferably a pre-wet insert that can be soldered (or alternatively, brazed) into place by heating the external surface of the HTF tube with a torch at the location of the positioned interior CIS. As will be obvious to those skilled in the art, the copper HTF tube is preferably brush-cleaned and fluxed at such interior alignment surfaces, as is normally performed in soldering copper plumbing. Preferably the CIS is bonded to the HTF tube's interior by means of a solidified metal that has a substantially higher melting point than the PWBL of the subsequently mated TCS/HTE pair. Thus, accordingly, the resulting assembly of copper HTF tube containing a multitude of such aligned and soldered cylindrical inserts, may be readily constructed in the field, or alternatively beforehand in a factory. Similarly, the corresponding multitude of precisely mated and clamped TCS' that are each aligned on the HTF tube so as to couple directly to a corresponding CIS (41) through the HTF tube wall, is also easily assembled at a construction site, or alternatively in a factory. In such preferred embodiments, the preferred standing seam solar roofing module is thus installed and provided the needed heat communication to an external load, without need for feed-through structures that require a multitude of liquid-air seals. Having The HTF carrying tubes located under the roof panels in the insulation area also allows means for preventing freezing of the HTF (e.g., water) in an overnight freeze. For example, with proper selection of HTF tube size, the HTF tube can be entirely or partially valved off from the remaining HTF circuit, and thereby provide overnight thermal storage that, in an alternative embodiment, can also be used to warm the roof and prevent formation of frozen water/vapor on or in the assembled roof.

Alternatively the HTE's are interfaced to the cooling heat transfer fluid (HTF) by means of sealed feed-through of the linear HTE directly into a turbulent flow of HTF within an HTF manifold, so that maximum heat transfer is achieved, as is commonly practiced and taught in the prior art of low- temperature solar thermal panels/arrays. A variety of fastening designs has been introduced and is commercially available. Whether the HTF manifold structure is mounted so as to intersect a plane of the heat pipes, or is mounted below the heat pipes and intersected by a fastening structure will to some degree depend upon the constraints of the architectural structure into which the embodied solar thermal roof panel is incorporated.

In the preferred embodiment, an aluminum HTE (3), with interior volume (12)

is fabricated as essentially a flat tube of trapezoidal sectional profile having a flat bonding surface (2), in FIG. 3(a). The HTE may have any shaped sectional profile including triangular rectangular, or round. The HTE is preferably an extruded length of aluminum that is subsequently welded to the its integral thermal contact structure (26), whereas this cross-sectional shape may also be formed by pressing a circular tube into the desired shape. The bonding surface of the HTE is fastened to the absorber-coated aluminum sheet by means of solidifying a metal bonding layer (4) for the

HTE/panel bonding means, and more preferably by use of a solder-like metal with a melting point in the temperature range of 200-400C, in FIG. 3(b). Most preferably, wetting of the aluminum components by a tin-based metal in range of 200-300C by first terminating the surfaces to be joined with a material layer that is readily wettable by the utilized solder. Preferably the joined surfaces of absorber-coated sheet and heat pipe are first sputter coated with a chrome/copper bilayer wherein chrome provides adhesion between the substrate and a copper top layer that may then be readily wet by the desired Sn-based solder compound.

In a second alternative embodiment, the solidified metal bond (4) is provided by higher temperature solders or brazes, such as with a Zn-Al (solidify at 440° C), a 88?%Al-12%Si (solidify at 577° C), AlCu brazes, etc.

Alternatively, the absorber-coated sheet and HTE of the preferred embodiments can be joined by other methods that provide acceptable thermal conductivity between these two components. Such alternative methods may be any compatible solder, braze, diffusion bond, hydraulic forming, MIG or TIG welding, ultrasonic welding, hypersonic welding, electrowelding, knurling methods, etc.

It is also preferred that the embodied solar-thermal roofing module be bonded to the HTE's before being coated with the absorber in a vacuum deposition system, preferably utilizing reactive sputtering, or alternatively evaporation or chemical vapor deposition, thereby ensuring that the absorber retains the desired aesthetic properties without discoloration over time due to a spatially inhomogeneous process history. Batch in-line deposition is also preferred for highly selectable hue of the absorber, whereby aesthetic preferences are more readily matched by the deposited absorber.

In an alternative preferred embodiment, in FIG. 3(c), the substantially flat portion of the inventive roofing module may possess one or more relatively low-profile linear corrugations (25) within the area between standing seams, such corrugations are utilized as wells for bonding of a similarly shaped HTE (the HTE may have any sectional shape - triangular, circular, rectangular, etc) so that increased contact area is provided, as well as providing an alternative means for providing an unobstructed flat back side, under surface (22) of the panel for contacting support members (36) such as purlins or battens, in FIG. 4(a). Such tube structures as the flat tube HTE with multiple interior channels are routinely manufactured and commercially available. It is preferred that the HTE is terminated with the preferred output end-structure (26) having integral dove-tail-type mating thermal contact structure. Whether support members are allowed contact to the back side surface (22) by means of the support regions (42) between HTE arrays, or by such corrugations, in FIG. 3(c), will depend in part on the desired appearance of the installed roof. In either case it is preferred that such means of unobstructed flat contact of the contacting surface (22) to the standard linear support members is provided so that use of custom support structures is avoided. Consistent with standing seam roofing systems of the prior art, the standing seam profile (23) may possess any of a large variety of interlocking profiles (7).

Such roofing modules of the preferred embodiments are preferably mounted onto a building with structural support consistent with typical installation of standing seam metal roofs, in FIG. 4. In particular, it is preferred that separate arrays of parallel HTE's be separated so as to provide support regions (42) that are contacted to supporting cross-members (36) separated by a standard support spacing, which is preferably in the range of 1-3 meters. The supporting cross-members (36) will preferably by supported by roof support structure (15), which may include a vapor barrier. The supporting cross-members are preferably in the form of linear battens, or alternatively are linear purlin structures suspended between rafters.

It is preferred that an assembled roof spanning the graded direction of an architectural structure, extending more than a couple meters, not have lapping panels, but instead have a single roof panel of adequate length. In accordance with the preferred embodiments, it is also preferred that longer lengths of roof panel comprise two or more parallel arrays of HTE's. A typical standing seam roof panel of the invention, in FIG. 4(b), has a first HTE array (47), a second HTE array (48), and a third HTE array (49), wherein these arrays are each thermally coupled to a separate linear segment of HTF tube (40), each having tube axis (43) (44) (45) , and are separated by support regions (42) for contacting support members (36). While there are three arrays in the present embodiment, it will be understood that the number of arrays may be any practical number from one to many. The relatively elevated end of the roof panel (71) in its assembled state will typically be covered by a roof ridge cap (14) or other form of flashing. The optimal number of HTE arrays integrated into a manufactured panel will in part depend on the demand for panels that may be cut to shorter lengths, corresponding to removal of one or more sections of HTE arrays, for application to smaller roof sections. The support regions (42) therefore also provide candidate regions for cutting the embodied roof panel to a shorter length so as to utilize a panel with less integral number of HTE arrays than formed into the original panel. In a typical installation of the preferred metal roofing panels, parallel arrays of HTE's at a given elevation in adjacent roof panels of an assembled roof, in FIG. 1(a), will accordingly all couple heat into one corresponding linear segment of HTF tube (40), in FIG 4(b). In a preferred embodiment, it is also preferred that the three, in the preferred example, separate linear segments of HTE tube each provide heat for a separate function of the building's energy requirements, in FIG. 4(b).

Accordingly, as an example, a first linear segment of HTF tube and attached HTE array (47) provides heat to the buildings hot water system; a second linear segment of HTF tube and attached HTE array (48) provides heat for the building's air-conditioning heat requirements, and, a third linear segment of HTF tube and attached HTE array (49) provides heat for (e.g., swing-cycle) refrigeration needs of the building. In this way, a single standing seam roofing module is disposed for providing heat into multiple heat-energy circuits, into separate loads, or into separate HTF's or other heat storage media. Any number of such arrays from one to several tens of arrays can thus be incorporated into a single panel.

In an alternative embodiment, in FIG. 5 (a-d), convective flow of air (55) between the vapor- deposited selective absorber layer (5) and bottom surface (92) of glass VGA is allowed to escape from the top region (71) of the embodied solar-thermal roof assembly. Such convectively flowing air may be desired in certain circumstances, such as in preventing a stagnation temperature and maintaining the roof panels below a particular temperature, or for providing such convective flow to a secondary application, such as interior heating. In the present alternative embodiment, sealed- interconnect means (56), located at the high end (71) of the embodied solar-thermal roof panel, is disposed for providing controlled flow of a convective flow into a flow-controlling valve (57). The sealed-interface means may be any appropriate means for directing and controlling conditioned air flow, known to those skilled in the art of air-conditioning, but is preferably an economically produced, gasket-sealed, aluminum plenum that preferably provides seals against the organic edge seal material (99) of the VGA, the spacer gasket (74), and the absorber-coated panel .

The flow-controlling valve (57) , having ports (57a, 57b) is disposed for releasing and directing convective flow of air that is optionally allowed to be flowing from clearance space between absorber layer (5) and bottom surface (92) of glass VGA, the valve means preferably having at least two positions comprising a shut position for blocking escape of convective flow, and a first open position for providing passage of convective flow back into the outdoors ambient air environment. Most preferably, the valve means has at least three positions, comprising the previous two positions, in addition to a second open position, in FIG. 5(c), that redirects convective air flow to heat-flow passage means (59) for directing the convective flow for use in, for example, indoor heating applications.

Such valve means accordingly include standard porting means associated with control of conditioned air, which may alternately comprise flapper valves, gated valves, or other common flow-directing means of the air-conditioning art. Accordingly, the embodied valve means incorporate vent-flow passage means (58) for directing heated air flow into outside ambient air, heat-flow passage means (59) for directing heated air for use in indoor heating,

entrance port (60) for directing air from inventive solar roof panel into valve means, and

interconnect (67) for providing passage of air-flow from volume between absorber (5) and VGA. (50) valve-mechanism providing, in the present example, a flow-directing characteristic of a three- way valve, though less or more ways may be readily envisioned.

In a futher alternative preferred embodiment, in FIG. 5(d), the embodied solar-thermal panel system of the preferred embodiments is utilized in conjunction with concentrating solar-thermal apparatus so that a heat transfer fluid that is directly or indirectly heated by solar radiation incident on the embodied solar-thermal panel system, is also heated by solar radiation incident upon a

concentrating solar system. Such a multiple-stage solar-heating arrangement may involve combination with any concentrating solar system of the prior art, such as parabolic trough concentrators, linear Fresnel reflectors, parabolic dishes, and various evacuated and/or concentrated solar-thermal collectors; moreover, in the first preferred embodiment, mid-temperature solar- thermal heating is efficiently provided by means of combination of the embodied solar-thermal panel system with tracking solar-thermal concentrator (102) comprising multiple conical frustums, as disclosed in co-pending patent application by same author, in PCT/US2011/00966, and the copending applications listed therein. By combination with such relatively small, modular, concentrating solar-thermal systems, HTF output temperatures well in excess of 250C may be efficiently obtained in a manner far more cost-effective than that provided by competing "mid- temperature" solar-thermal means, such as parabolic troughs or linear Fresnel reflectors. Sorage means (103) for storage of the HTF preferably comprise a bi-modal, two-compartment storage container, comprising an inner insulated, preferably vacuum insulated, container (103b), the inner container disposed within a larger outer container (103a), so that a higher temperature HTF returning from the concentrating solar-thermal means (102) may be flowed to the inner container, and HTF returning from the embodied roofing panels may be flowed to the outer container (103a).

While the preferred embodiments comprise bulk component - namely a roofing panel and the integral HTE's - it will be appreciated that other metals may be alternatively used, such as copper, carbon composites, stainless steel, organic/inorganic composite materials, and so on. It will also be appreciated that the combined elements are not limited to strictly linear roofing systems, as a gently curved roof panel (in the long axis of the panel) may also be envisioned utilizing the same coating and installation approach. Roof types are most preferably standing seam, but may also be flat seam, or simple corrugated.

It is to be understood that particular elements of one preferred embodiment disclosed herein will readily be utilized similarly in conjunction with other embodiments.

In an alternative preferred embodiment, the embodied solar-thermal panel (1), is provided for added efficiency in harvesting solar energy by means of a flat vacuum barrier assembly (87), in FIG. 6-8. Such flat vacuum barrier assembly comprises a vacuum-insulated double-glazed glass panel wherein two panels of glass are thermally isolated from each other by an evacuated space formed between the two glass panels. In its preferred embodiment, the vacuum barrier assembly (VBA), comprises a pair of borosilicate glass panels, which are substantially of equal and matched planar dimensions, and hermetically sealed together by means of a continuous metal gasket seal (85), which seal is disposed at the periphery of the glass panels so as to seal off the evacuated volume provided between the two panels.

The metal seal material is preferably of a Kovar or similar composition, and is preferably formed to possess a symmetrical convolute profile. More preferable, the metal gasket possesses a gull-shaped profile, in FIG. 6(b), which provides preferably one, or alternatively more than one, central bellows-like ridge, separated on either side by relatively broad sectional regions for roughly matching the thickness of the first and second glass panels, so that the glass panels may be disposed within either side of the central convolute feature (75) of the metal gasket, thereby effectively trapping the gasket in between the first and second glass panels .

In the present embodiments, a vacuum space (84) is provided between the first and second glass panels by means of a plurality of parallel glass fibers (81), wherein such glass fibers preferably comprise a borosilicate glass, and more preferably, a borosilicate glass having a glass softening temperature T_g, slightly less than that of the first glass panel. A VBA of the present invention preferably utilizes a modular construction that enables exceptionally low clearances for installation in low profile, flat, solar-thermal panels. Accordingly, the evacuated space (84) is preferably less than 4 millimeters across, and more preferably less than a 1.0 millimeter gap. Accordingly, borosilicate fibers utilized are most preferably on order of 1 millimeter or less in diameter.

It is preferred that the VBA is constructed such that the first glass panel (80) is formed into a panel- fiber assembly by means of pressing a plurality of glass fibers into the first glass panel on the side opposite the first surface (91). This pressing of the borosilicate fibers into the first glass panel (80) is performed by a heated planar press (86), that is preferably surfaced with a release material, preferably a boron nitride layer, accordingly suitable for pressing and releasing the borosilicate fibers. The press is according heated to a temperature at or near the Tg of the glass fibers, so that pressing pressure, combined with slow flowing of the glass fibers, results in a well-controlled bonding of the glass fibers to the first glass panel. In this way, rigid fastening of the glass fibers to the first glass panel is accomplished continuously along the length of the fiber.

An integral assembly of first glass panel (80) and plurality of parallel glass fibers (81) is thus formed, in FIG. 6(b), and is thus suitable for mating to the second glass panel so that the glass fibers are rigidly fixed between the two panels and disposed to provide a regular spacing and support structure between the two panels. It is preferred that the panels are rectangular, or square, each having rounded corners for providing a continuous mating surface for contact to a continuous metal gasket (85). The first glass panel and integral plurality of fibers is accordingly mated to the second panel so as to form the embodied double-glazed panel, wherein the peripheral metal gasket, preferably comprising a thin preformed Kovar strip, is provided between the first and second glass panels so as to be trapped between the two panels, in FIG. 7. The preferred borosilicate glass panels of the embodied VBA are preferably edged so as to possess a particular sectional profile, in FIGS. 7(a) and 7(b) . Preferably the edge profiles of the two glass panels are such that the edges are rounded at both inside edges (94) and outside edges (93), and more preferably such that the inside edge surface (94) possesses a radius substantially larger than the radius of the outside edge surface (93), wherein a relatively open space is formed between the respective inner-edge surfaces of the mated panels. The convolute profile of the metal gasket is preferably formed so that part of the gasket substantially occupies the space formed between the respective inner-edge surfaces of first and second panel.

It is preferred that the borosilicate glass panels are constructed of a glass having a coefficient of thermal expansion (CTE) slightly different, and preferably smaller, than the Kovar (or other metal) seal gasket. It is further preferred that the VBA be assembled such that the metal gasket exerts a compressive force onto the first and second panels during normal operating temperatures, preferably in range of 0-150 Celsius. A compressive stress (101) is provided to the glass panels by the metal gasket preferably by assembling the VBA at a temperature outside the range of VBA operating temperature range. Preferably, these three structural components of the VBA, first and second panels, and metal gasket, are assemble together at a raised temperature, preferably greater than 200 Celsius. The metal gasket having a preferred CTE slightly greater than that of the glass panels, will accordingly expand at a greater rate, such that the panels may pressed together while the gasket is expanded so as to encapsulate the outer edges of the two respective panels. On cooling, the metal gasket accordingly will contract about the edge-surfaces of the two panels, thereby exerting a compressive force on the panels.

It is further preferred that the glass-to-metal seal is formed between the metal gasket and each of the outer-edge surfaces (93) of the first and second glass panels.

After the initial press-assembly of the VBA, appropriate Kovar-borosilicate glass solder is disposed in the glass-to-metal seal region adjacent outer-edge radiused surface (93) and the unsealed assembly is placed in a vacuum furnace, whereby the VBA vacuum space (84) is evacuated, and subsequently, the glass-to-metal seals (88) are formed at or near the glass solder's melting temperature, in FIG. 7(b)

The thickness of the assembly comprising first and second glass window, separated by glass fiber spacers (81) is preferably such that the top surface (91) of glass vacuum barrier assembly and bottom surface (92) of glass vacuum barrier assembly are accordingly separated by a distance, S, comprising the added thicknesses of first glass panel, second glass panel, and the glass fiber (81). While the metal gasket seal (85) may have a sectional profile width, w, corresponding to distance, S, it is more preferable that width w is slightly larger than distance S, so that an over-extended lip of over-extended thickness, d, is provided for joining by the seal material (88), preferably wherein d is such that 0.10 mm < d < 5.0 mm, and more preferably 0.30 mm < d < 2.0 mm, in FIG. 7(b).

In an alternative embodiment, the outward-facing bottom surface (92) of the second glass panel (82) is coated with an electrically conductive transparent oxide (TCO), indium-tin oxide or other TCO material, for providing selective transmission and IR reflection.

It is preferable that the planar dimensions of the embodied VBA be relatively limited so that an assembled section of roof— or alternatively a roof-top solar-thermal module utilizing the embodied panel construction ~ comprise an inter-connected grid of many such VBA's. A VBA of the preferred embodiments possesses a width, designated as the dimension measured parallel to axis (72), in FIG. 8(a), preferably in a range of 20cm to 60cm. A VBA of the preferred embodiments possesses a length, designated as the dimension measured parallel to axis (73), in FIG. 8(a), preferably in a range of 30cm to 150cm.

In a further preferred embodiment, the assembled and sealed VBA of the present preferred embodiment is further processed to have an integral organic edge-structure, preferably comprising an integral silicone gasket. The integral organic edge-structure (99) is preferably formed around the periphery of the VBA, so as to encapsulate the metal gasket and the glass-to-metal seals of the VBA. In the case that the integral organic edge structure is formed of silicone, it is preferred that pre-existing methods for mold-forming a silicone structures are utilized, preferably utilizing an according negative mold and vacuum impregnation or vacuum flowing means to form the silicone gasket. It is also preferred that the integral silicone gasket be formed directly onto the VBA, though it is also possible to make the gasket separately and attach such elastic gaskets to the VBA after forming. In either case, the silicone edge-structure is attached to provide hermetic sealing to the glass-to-metal seal regions of the VBA. It is also preferred that the silicone edge-structure be formed so as to form less-rounded corners than those formed by the glass-to-metal seals, preferably such that the silicone edge-sturucture comprises right angles, and the organic-edged VBA is thus formed to have a rectangular profile with substantially linear edges, in FIG. 8(a). Accordingly, organic side edges (96) of the silicone edge-structure will have a substantially continuous and linear exterior profile for enabling a continuous seal to an adjacent linear surface, in FIG. 8(c).

It is further embodied that the integral silicone edge-structure is formed to provide mating means between two separate VBA's. Accordingly, the silicone edge-structure is formed to provide a female end-mating structure (98) along a first linear edge of the VBA, and a male end-mating structure (97) along the linear edge of the VBA opposite the first linear edge, in FIG. 8(b). The female and male end-mating structures are accordingly formed such that, identically made, adjacent VBA's of the present invention may be joined to form a continuous line of successive VBA having a continuously sealed surface, thus forming a linear joined assembly (77) of VBA's , in FIG. 8(d), wherein the male and female end-structures are mated to provide a seal against water, moisture, or other environmental elements.

In accordance with the preferred embodiments of the previously disclosed linear joined assembly of VBA's (77), such resulting continuous line of VBA's may be integrated into the disclosed solar- thermal panel, so as to provide a vacuum-insulated barrier between the absorber layer (5) and the outside environment of the geographic location in which the disclosed solar-thermal apparatus is installed. In the present preferred embodiments utilizing a grid of multiple VBA's, in FIG. 9, a solar-thermal panel section comprises three of the individual panels (1), Each panel (1) utilizes a linear array of three HTE (three panels shown). Each of the three HTE on a single panel (1) deliver heat to one of three respective separate HTF pipe sections (40), having respective axes (43, 44, 45), such HTF pipe sections incorporated within the corresponding HTE arrays (47) (48) (49), as in previous embodiments. As in previous embodiments, the A solar-thermal panel section, which is preferably a roofing section, or alternatively, a solar-thermal roof-top panel section, of the present embodiments, comprises elements of the previously embodied standing seam roofing system.

In the presently embodied solar-thermal panel section, each solar thermal panel (1) is joined to an adjacent panel (1) by means of a seam structure. The underside of the section, in FIG. 9 (a) is similar to previous embodiments, wherein the support members (39) are preferably disposed at open regions provided between HTE arrays (47),(48),(49) . Such support members may be in the form of roof support members, such as purlins or battens, or be purlin-like members supporting the embodied section within a modular, non-roof, solar-thermal panel.

In the event that the standing seam structure is inverted, the adjacent linear assembly's (77) of VBA's may adjoin the adjacent line of VBA's by means not incorporating a standing seam. It is not intended that the invention be limited to the specific embodiments disclosed, as a variety of linear seam structures and linear seal mechanisms may be envisioned for a grid-like array of the embodied VBA's. Accordingly, opposing organic edge-structures of the encapsulated VBA edges may be formed in a variety of mating structures. The seam region (23) joining adjacent panels (1)

preferably provides a metallic seam structure disposed between adjacent VBA lines (77), so that individual VBA lines may be repaired or replaced without effecting an adjacent VBA line. Spacer gaskets (74) preferably provide a clearance between VBA and underlying absorber surface (5) of the solar-thermal panel (1).

Each VBA line (77) is preferably sealed within a separate metal enclosure by means of edge-sealing spacer gaskets (74), preferably formed of an ethyl vinyl acetate (EVA), or alternatively a silicone, which spacer gaskets provide both a sealing interface to the organic edge structure of the VBA, as well as a guide means for collimating the VBA line at a predetermined distance above the underlying panel (1). Adjacent VBA lines are accordingly suspended by the organic spacer gaskets that contact and butt against standing seam surface (70).

The embodied standing seam solar panel incorporates a bracket structure for mounting and securing the panel to the support members (36) such as metal purlins, in FIG. 10(a), wherein it is preferred that such support members are separated from the solar-thermal panel by a support insulation layer (76), preferably an silicone rubber strip adhered with a silicone adhesive. It is most preferred that the support surface provided by the support members, preferably including support insulation, provides alignment of the embodied solar-thermal panels HTE output surfaces (26) with its corresponding TCS (27), which will preferably be pre-installed on the copper HTF pipe (40) in a HTF circulation circuit. In this way, the support members (36) and HTF circuit may be installed according to a template so as to provide a single plane so that the solar-thermal panels (1) may be subsequently laid over the support members and HTF circuit, and whereby the panels may be easily slid into an engagement position with the underlying TCS' locations.

The HTE output end structure (26) and mating TCS (27) may have a variety of interlocking shapes. In the first embodiment the mating structure comprises a straight, rather than tapered, channel, wherein the preferred dovetail cross section of the output structure (26) is preferable formed as a substantially flat plate of relatively wide and shallow sectional profile. Preferably the mating end structure plate (26) possesses a thickness less than 2 cm and width greater than 4cm, in FIG. 10(b). In this way, the panels are maintained with accordingly minimum distance between HTF pipe and absorber layer (5), wherein distance, D, between HTF pipe and absorber layer is preferably less than 10 centimeters in the first preferred embodiment, and more preferably less than 3 centimeters, thus enabling less thermal losses relative to other designs.

In the preferred embodiment, a bracket structure (69) is utilized for securing panels to the support members, in FIGS. 10-11, such bracket mean attaching to support members preferably by mean of conventional fasteners secured through a fastener hole-pattern (66) in the bracket. Such brackets preferably provide alignment and clamping means, such as tabs (65) that allow for thermal expansion of the panel in the longer dimension of the panel. Pairs of seam structures are secured together in a standing seam assembly (23) by means of a, preferably metal, linear seam joining means (9). It is preferred that the joined seam structure also incorporates means for securing and sealing the VB A's located on either side of the seam sturcture, It is also preferred that the seam assembly incorporate means for insulating the internal seam structure (7) (70) of the installed panels (1) so that there is an organic barrier between the standing seam structure (7) (70) and the ambient air of the outdoor installation. Accordingly a metal spring clip (10) is laminated with silicone lamination (11) to simultaneously provide both an organic-insulated outer surface, as well as clamping means for securing and sealing the VBA side edges (96) within the spacer gaskets (74).

As previously embodied, the solar-thermal panel construction of the present invention may be utilized as a roof section or integrated into a dedicated solar-thermal module that is used on roofs or other locations. For example "purlin" placement in previous embodiments may correspond to a corresponding support member (36) utilized in a free-standing solar-thermal array. Earlier embodiments of solar-thermal sections incorporating VBA's may be utilized in roof-top solar- thermal modules (62), in FIG. 11(d).

It is not intended that the foregoing preferred embodiments be construed in anyway to limit the invention to the embodiments herein, as various further embodiments incorporating the structures and spirit of the invention may be readily anticipated by those skilled in the art .

Claims

What is claimed is:

1. A solar-thermal panel, comprising:

a. ) a thin planar support structure formed from a substantially non-porous material, the planar structure having a first side and a second side, a spectrally selective coating formed on the first side, a seam structure formed into opposing edges of the planar support structure;

b. ) a heat pipe structure attached to the second side, the heat pipe structure having one end comprising a contacting structure, the contract structure disposed adjacent the support structure, opposite to the coating; and,

c. ) a metallic interlayer disposed between the heat pipe structure and support

structure, so that solar heat absorbed by the selective coating is transported to the heat pipe structure.

2. The solar-thermal panel of Claim 1, wherein the heat pipe is an extrude aluminum pipe of roughly planar aspect.

3. A standing-seam roof panel having a vapor-deposited, spectrally selective absorber, comprising;

b. ) a heat pipe structure attached to the second side, the heat pipe structure having one end comprising a contacting structure, the contract structure disposed adjacent the support structure, opposite to the coating; and, c.) a metallic interlayer disposed between the heat pipe structure and support structure, so that solar heat absorbed by the selective coating is transported to the heat pipe structure.

4. A transparent, vacuum-insulated glazing for providing thermal insulation,

comprising:

a. ) a first glass panel, the first glass panel having a first side and a second side, a plurality of glass spacers disposed on the first side;

b. ) a second glass panel, the second glass panel having a first side and a second side, the first side contacting the glass spacers so that a cavity is formed between the first glass panel and the second glass panel, the second panel having planar dimensions roughly equal to those of the first panel;

c. ) a metal gasket disposed along the periphery of the first panel and second panel, so that the first panel and second panel reside within the interior of the metal gasket, whereby a glass-to-metal seal is sustained so as to provide an evacuated space between the first panel and the second panel.