Patent Application
20110088340
The present invention relates to the area of solar water heating collectors, which absorb the radiation from the sun and convert the radiation into heat and convey this heat energy suitable for heating purposes in a building, a swimming pool, for process energy or tap water. Alternatively the panel transmit energy from the collectors to the atmosphere during a period of time where the outdoor temperature is lower than the interior temperature in the building.
The traditional solar water heating systems available on the market today change all buildings visual character and appearance significantly. This limits to some extent the use of solar panels, especially in older and listed buildings. For this reason it has become increasingly difficult to meet the objective of increased use of solar energy as most countries and international organizations have set. There are several factors limiting the spread of the use of solar collectors. Price is clearly the primary, but alteration and change of the building and technical complexity is of significant scale.
Some terms to be aware of when discussing roofing materials and their energy efficiency are; solar reflectance, emittance and the Solar Reflectance Index (SRI):
A flat collector consists of a thin absorber sheet (usually aluminium or copper to which a black or selective coating is applied) backed by a grid or metal coil of fluid handling tubing and placed in an insulated casing with a glass top cover. Fluid is circulated through the tubing to remove the heat from the absorber and transport it to an insulated water tank, a heat exchanger, or some other device for using the heated fluid.
Instead of metal collectors, some new polymer flat plate collectors are now being produced in Europe. These may be wholly polymer or may be metal plates behind which are freeze-tolerant water channels made of silicone rubber instead of metal. Polymers, being flexible and therefore freeze-tolerant, are able to use plain water instead of antifreeze, so in some cases they are able to plumb directly into existing water tanks instead of needing the tank to be replaced by one with extra heat exchangers.
Evacuated tube collectors are made of a series of modular tubes, mounted in parallel, the number of which can be increased or reduced as hot water delivery needs change. This type of collector consists of rows of parallel transparent glass tubes, each of which contains an absorber tube (in place of the absorber plate to which metal tubes are attached in a flat-plate collector). The tubes are covered with a special light-modulating coating. In an evacuated tube collector, sunlight passing through an outer glass tube heats the absorber tube contained within it.
All the above solar collectors will change the appearance and character of a building on which they are mounted, considerably. Flat collectors are typically incorporated into a rectangular box having dimensions of about 1×2 meters with a glass pane at the top and about 100 mm insulation at the bottom. This design limits the prevalence of solar collectors considerably, but their costs and complexity and the necessity to rebuild the constructions involved and change their appearance and character are a more important limitation for their common distribution.
U.S. Pat. No. 4,244,355 discloses a solar panel system comprising solar panel modules, each of which has a collector housing constructed of high temperature fibreglass reinforced plastic, die stabbed steel or aluminium covered by a fibreglass reinforced plastic translucent top portion. The collector housing contains a collector plate preferably constructed of copper with an absorptive coating. Between the top cover and the collector plate there is a dead air space and at the underside of the collector plate there is a plurality of tubes for carrying a liquid to be heated by the solar collector. This solar collector module is mounted visible in a roof construction instead of a part of the normal roof elements used for the climate shield.
US patent application publication no. 2005/0199234 A1 discloses a heating and cooling system which is to be structurally incorporated into an exterior building portion having an interior side. At least one support member having a fastening portion and a channel is mounted proximate to the interior side of the exterior building portion and at least one radiant heat tube is disposed in each channel and mounted proximate to the interior side of the exterior building portion by each support member. A heat-carrying medium is transmitted through the separated radiant heat tube and a radiant heat reflective surface is mounted proximate to the radiant heat tube. This heating and cooling system is intended to be incorporated invisible below a climate shield on a building, but the radiant heat tube is not an integral part of the support member which furthermore has a rather limited surface area so that only a small proportion of the underside of the climate shield is covered or may be in thermal contact with the support member. This creates bad transmission of heat energy between the underside of a climate shield and the heat-carrying medium in the radiant heat tube.
U.S. Pat. No. 4,111,188 discloses an extruded metal solar collector roofing shingle for mounting in multiple shingle, edge overlapping, parallel array fashion across laterally spaced inclined roof rafters of a building structure, which shingle comprises an elongated planar sheet portion having upper and lower surfaces and laterally opposed upper and lower edges, an integrally extruded fluid conduit within the sheet portion and protruding from the lower surface of the sheet and integrally extruded locking means along opposed lateral edges of the sheet portion for forming a mechanical interlocking connection between overlapping edges of respective sheet portions of adjacent shingles. Optionally a light transmissive plate of rectangular configuration and of a size generally equal to that of the shingle is mounted to the upper surface of the shingle and spaced there from to reduce loss of heat from the shingle. Clearly this shingle is not designed to be incorporated invisible behind a climate shield of a building and there is no hint in the patent to obtain such object.
Also U.S. Pat. No. 4,221,208 discloses an extruded metal solar collector roofing shingle of similar design for mounting in multiple shingle, edge overlapping, parallel array fashion across laterally spaced inclined roof rafters of a building structure. However, nor this shingle is designed to be incorporated invisible behind a climate shield of a building and there is no hint in the patent to obtain such object.
Finally U.S. Pat. No. 4,083,360 discloses a solar energy collector adapted to be mounted in and to form part of a building structure. This collector comprises a thin parallelepiped case having a top wall of metal plate, to which bars are welded on the outer surface and a pipe conveying a fluid is welded on the inner surface. This case is designed to be placed below a window of transparent hollow elements, e.g. tiles of glass, cut out in a part the roofing on a building. There is no hint in the patent to use it in other manner, so neither this collector aims to be incorporated invisible behind a climate shield of a building.
The present invention has the object not to change the building's visual appearance. Therefore, the solar panels must be 100% integrated under or inside the external surfaces, which are to be used as an envelope. In short, the term “invisible collector” could be used to describing this invention. However, the use of a building as an envelope for a solar collector reduces the thermal efficiency, primarily due to a reduction of the absorbed short wavy energy from the sun caused by colour and surface coatings on the building. Also the wind influences the surface exposed to the sun by cooling the surface which absorb the sun's energy. To counteract these adverse conditions the surface area may be increased by utilising the entire roof surface and/or facade of a building. This can be done because the total price for implementing of the suggested collector in a building is less than the application of conventional externally mounted solar collectors.
The present invention relates to a solar energy collector panel intended for invisible incorporation behind and in thermal contact with a climate shield of roofing felt on a building, said panel being made of a heat-conducting material and having at least one through-going fluid-impervious duct embedded in said panel for passing a thermal energy carrying-capable fluid through it and having or being attached to a member of heat-conducting material and substantial surface area intended to be mounted in direct physical contact with said climate shield.
Thus, the transfer of energy from the climate shield to the collector panel of the present invention is essentially performed by direct heat conductance or convection.
In an embodiment of the collector panel according to the invention the roofing felt is bituminous a material(s) or tar board.
In another embodiment of the collector panel according to the invention the heat-conducting material(s) is (are) a metal.
In another embodiment of the collector panel according to the invention the heat-conducting material(s) is (are) a metal selected from the group comprising aluminium and aluminium alloys, copper and copper alloys, iron and iron alloys, in particular the different types of stainless steels.
In a further embodiment of the collector panel according to the invention the heat-conducting material(s) has (have) a thermal conductivity of more than 10 Wm2/K.
In a further embodiment of the collector panel according to the invention the panel with its fluid-impervious channel or duct has been produced by an extrusion process.
In a further embodiment of the collector panel according to the invention the surface area of the flat member covers at least 50%, more preferable at least 80%, and most preferable 90% of the area of the climate shield.
In a further embodiment of the collector panel according to the invention the surface area of the flat member covers nearly 100% of the area of the area of the climate shield.
In a further embodiment of the collector panel according to the invention the at least one through-going fluid-impervious duct is placed above the surface of the flat member and optionally the outer surface of said duct has the form of a triangular list.
In a further embodiment of the collector panel according to the invention the at least one through-going fluid-impervious duct is placed below the surface of the flat member and preferable is embedded in or surrounded by insulation material.
In a further embodiment of the collector panel according to the invention the solar energy collector panel comprising said at least one through-going fluid-impervious duct has a body having two opposite wings, each provided with a slot intended for receiving a flange of a heat-conducting plate member in a snugly fit.
The invention also comprises a building having a climate shield of bituminous roofing felt or tar board and a solar energy collector panel according to the invention invisible incorporated behind and in thermal contact with said climate shield.
In an embodiment of the building according to the invention the climate shield constitutes the roof or a part thereof on the building.
In another embodiment of the building according to the invention the insulation material is mounted between said solar energy collector panel and the remaining construction part of the building.
In a further embodiment of the building according to the invention the climate shield, solar energy collecting panel and insulation material are mounted on top of an industrial roof surface of standing seam metal based sheets optionally being highly trapezoidal corrugated in cross-section.
In a further embodiment of the building according to the invention each end of said at least one through-going fluid-impervious duct is connected by tubing to a heat exchange appliance in said building, such as a water heater, a radiator, a central heating or cooling unit, a floor heating unit, or a swimming pool.
In another embodiment of the building according to the invention more than one solar energy collector panel are incorporated behind and in thermal contact with a climate shield of a building and each end of the through-going fluid-impervious ducts in the panels is connected by manifolds and tubing in parallel or series to a heat exchange appliance in said building, such as a water heater, a radiator, a central heating or cooling unit, a floor heating unit, or a swimming pool.
The invention further comprises a building having a climate shield of bituminous roofing felt or tar board and at least one solar energy collector panel according to claim 1 invisible incorporated behind and in thermal contact with said climate shield and wherein each end of the through-going fluid-impervious duct in the panel is connected by tubing to a heat exchange appliance in said building and is used to convey heat from the interior of the building to said climate shield from which it is radiated or conducted to the surrounding environment.
The invention further comprises a use of a solar energy collector panel according to the invention by which the collector panel is incorporated invisible behind and in thermal and physical contact with a climate shield on a building, wherein the climate shield is adhered to a substantial surface area of the collector panel with a bituminous, tar material or other adhesive material.
The invention also concerns a use of a solar energy collector panel according to the invention by which the collector panel is incorporated invisible behind and in thermal and physical contact with a climate shield on a building, wherein the climate shield is adhered to a substantial surface area of the collector panel with a bituminous or tar material or other adhesive material.
The climate shield is preferable bituminous roofing felt or tar board.
The slope of a solar heated liquid cooled surface having integrated a collector panel according to the present invention a climate shield of a building can be chosen freely between horizontal and vertical and is only limited by the manufacturer's instructions for the climate shield. Thus, the collectors of the present invention are “invisible” as a result of being integrated behind the climate shield, thereby not affecting the view of the building, which is visually unmoved.
Buildings provided with the above-described collector principle do not appear visually different from similar buildings without a collector. Hence, the collector principle of the present invention can be used also in old buildings, listed buildings and buildings in residential areas which are subject to visual modification restrictions.
Bitumen based roofing felt is typically delivered in the form of rolls which are laminated around a reinforcing fibre fabric. The top surface layer of bitumen is often covered with a layer of ultraviolet protective particles, often minerals, shale or coal, and a further layer of bitumen on the underside is used for bonding attachment to the base roof surface. For example a layer of closely located wood boards or plywood sheets are primed with asphalt to improve adherence of a roofing felt roller which is welded or glued to the base. Alternating seams of first layer of cardboard on the wood surface overlap seams of second layer and are melted together.
In some countries this type of roofs are formed with small individual bitumen felt slates placed in close proximity and with appropriate overlap provides a rainy climate and windproof screen. Especially in the U.S., this roof, popular known as shingles, is typically nailed flat on a plywood substrate, but could be glued solid as an alternative to nailing.
The present invention is, among other things, carried out on a 10°-40° sloped roof surface lined with traditional bitumen roofing felt affixed to an underlying heat conductive surface, for example metal based, in direct contact with a fluid in the integrated tube or channel to receive the accrued and through the heat conductive surface transported energy from the sun and further carrying the heated fluid to for example a technical heating facility in a building. This cools the roof surface. An appropriate thermal insulation layer, e.g. polystyrene, mineral fibres, reflective foil or combinations thereof, is preferably placed below the collector panel.
The volume of the triangle list, which traditionally is used on the top surface of a roof and which is covered with an asphalt or tar felt strip, is the basis for the transportation area of the cooling fluid. In other words, the triangle is replaced with a system inside the “triangle list”, which allows a fluid to pass and therefore does not change the traditional visual experience of the roof. The typical distance between the triangle lists is adapted to the traditional tar felt rollers' widths. Triangle lists comprised by this invention can usefully be placed closest possible, so that the narrow tar felt strip rolls, for example. 600 mm width, are used, replacing the often used tar felt strip width of 1,000 mm for optimised energy absorption.
Buildings provided with the above-described integrated solar panel examples are not different from the visually similar buildings without a collector. Thus, the collector can be usefully applied to older buildings or buildings in residential areas, which are subject to visual restrictions. Or, the benefit of a building, which has been listed with a collector of the invention implemented in the building, includes other than the roof surface.
The solar panel may be manufactured by an extrusion process used to create long objects of a fixed cross-section. By such process the material to be used is pushed in a heated condition through a die having the desired cross sectional shape. Hollow sections like the through-going channel or duct are usually produced by placing a pin or piercing mandrel within the die. The extrusion process may be continuous or semi-continuous and create endless panel or panels having a length of typically 20-30 meters, which are straightened, cooled and cut into desired lengths of typically 6-8 meters ready for shipment. —In the case that the material is aluminium, extrusion blank it is heated as a ticket to about 400° C. before it is pushed through the die.
The architectural principle of installation of triangle lists under asphalt cardboard is sometimes on bitumen felt roofs, but at the top of the envelope and in the same direction as the rainfall is moving on the roof. The triangle lists are used advantageously as a useful volume for the inclusion of the cooling pipe. For example, a comprehensive and thermally well conductive surface of a thickness between 0.1 to 100 mm and thermally corresponding with the metal structure triangle list is located under a roofing felt membrane with integrated cavities for the built-cooling arrangement. In or close to the ridge of the roof and/or roofing foot refrigeration triangle list connections are assembled with other technical connections, for example tubes passed through holes in the underlying insulation, metal and wood diaphragm membranes. The application of sheeting insulation with a relatively high pressure resistance directly on the wood membrane mounted on the roof reduces the number of cold bridges. The cooling of the roofing felt further keeps its temperature under control for a prolonged life. The aluminium metal membrane is attached with screws through corresponding holes in the metal triangle list wings and through the insulation boards, which maintain the insulating material. The metal plate membrane provides an excellent anchor for affixing roofing felt roof envelope.
The dimensions of the triangle list (alternatively performed as a semicircle or other smart design) are determined by the cooling medium chosen to be a liquid or a gas. The system is simplified in the case air is elected, since a triangle list as a profile transports gas of ˜1:800 density to capture the heat in the house. This, however, imposes the channel in the list to be several times greater than if a liquid was to be transported.
If the triangle list is coated exteriorly with an anticorrosive, advantageously having a dark colour, the profile requires no additional coating with roofing felt, which facilitates the execution of the roofing tasks.
Alternatively, the profile forming the means for transporting the cooling fluid in the form of a triangle list is externally attached thermally on the heat conductive metal membrane and finally covered by affixing roofing felt. In each end of the profile connections for fluid input and output are provided. Some people would consider it prudent that triangular route is equipped on the back regularly mounted with threaded pieces, which allows fastening with springs, washers and nuts in the side of the roof wood membrane through insulation, springs to compensate for material extensions. In practice the triangle list or its alternatives are placed either on the top or on the underside of the envelope. Located on the top plate conventional insulation can be used without further processing. Located on the underside a similar track record in the underlying insulation must be performed.
An alternative to a triangle list placed perpendicular to a building's axis is a similar structure built (as plank coverage) on the roof along the bottom of each asphalt felt strip fastened and partly in bitumen cast in a potentially oval cooling tube with adhesion surfaces with possibly mounting holes . This cooling tube can usefully be made as an extruded aluminium profile coated with a dark colour. Alternatively it can be rolled up, for example from 1-4 mm thick metal bands or sheets, with the integrated cooling tube. The distance between these cooling tube profiles may usefully be limited to between 50 and 1,000 mm, favourably between 150 and 500 mm. At a greater distance between cooling tube profiles a heat conductive plate-shaped material is placed, to which the roofing felt is bonded. Flexible connections may be located under the cooling tube profiles so that thermal expansion can be absorbed. All cooling tubes are assembled with for example two manifolds, one on each side of the building, to other technical and hidden connections with usually installed wind coverage. This principle can be extended, if necessary, to take the form as a hybrid between the principle plate coverage and plank coverage as described in the technical literature, here through the use of straight wall as vertical cladding and not vertical roof.
Industry roofs are typically built up through the installation of a system of corrugated metal sheet metal for handling snow load and the like. The installation of insulation at the top of the trapezoidal plates and a layer of heat-conductive plates on the top of the insulation provides an opportunity for the placement of the cooling profiles in close thermal contact with metal plates with integrated channels and can be used as a means of transporting a fluid to cool the roof.
Roofs equipped with triangle lists or lists plank as architectural principle are national contingent phenomena. Most countries use flat plane and completely flat roofs. A simple and compatible concept will be compact extruded profiles with slits in both sides which mechanical and thermal correspond with one on each side placed heat conductive metal sheet plate—stored inside the climate shield. These metal sheet plates can be adapted to various widths so as to achieve a suitable distance between the fluid operating profiles with integrated cooling tubes. Thus, roofing felt membranes combined with a comprehensive and thermally well conductive surface of a thickness between 0.1 to 100 mm are thermally corresponding with a metal structure profile with integrated cavities with the built-in cooling arrangement.
Fluid transferring flexible tube connections from the next neighbouring cooling device are connected continuous with flexible through pipes corresponding with profiles of custom slits in the underlying insulation without breaking the water tight membrane on the wood membrane on the timber support. Thus is the complete solution deployment in depressions alone in isolation. The application of sheeting insulation with a relatively high pressure resistance directly on a wood membrane mounted on roof rafters reduces the number of cold bridges.
Through the cooling effect the operating temperature of the roofing felt is kept under control for a prolonged life. The aluminium metal sheet membrane of the invention is attached with screws through corresponding holes in the profile sheet's heat conducting wings and further through insulation plates by which the insulating material is mechanical fastened. The metal plate membrane provides an excellent anchor for affixing bitumen roofing felt and other roofing materials.
An alternative and also preferred design is a centrally located small profile with a fully integrated tube with slots for sheet connections. These sheets of variable width act as a means for transporting energy from larger bitumen roofing felt surface areas to a fluid which cool the roof surface heated by the sun. Slot widths are adjusted so that the heat conductive distance plate easily may be squeezed into the slots for both a close mechanical and particularly thermal successful session. Blunt are composed of parallel wings as an integral part of the body in mechanical contact with the heat conductive distance plates or sheets transporting energy in the desired direction. The heat conductive distance plates as accessories to the profile are either completely flat or have shaped strips to fit snugly inside the slots. The heat conductive plate may be rolled in the shape of a flat piece of metal. The heat conductive distance plates may be extruded or rolled of metal having good thermal conductivity such as aluminium or the like. In practise a roof surface lined externally with roofing felt are in close contact with a system of parallel underlying heat conductive sheets mounted on a thermal insulation placed on a supporting membrane of wood or metal on the rafters. The heat conducting elongated plates fixed into the slots may have parallel sides or be performed with varying widths such as trapeze shaped according to the task. The solar panel may preferably be mounted mechanically on suitable insulation materials with slots to cover the profile shape in order to improve the solar panel invisibility. Mechanical fastening is preferably done with a suitable number of screws or nails passing through holes both in the heat conductive sheets and the insulation materials into the wood structure support below the insulation material.
The central profile with the integrated tube may have lengths varying from less than one meter to more than 20 meters. Though for ease of use and transportation they are supplied in lengths of 2-6 meters and each profile is fitted with threaded connections in each end. Such pipe threads connections for in between the many profiles to obtain a fluid transporting system with series connection. Assembling the more than two profiles with hoses, preferably flexible metal hoses, in serial connection for energy exchange between the fluid and the solar panel system. The combined tubes in the profiles are further connected via flexible metal hoses to a pump for fluid exchange with a heat storage or a heat conveying system.
The connecting heat conducting sheets, one sheet connected on each side of the profile, have preferable the same length as the profile. Such sheets range from 100 mm to 1000 mm in width, preferably from 100 to 500 mm. The total single solar panel widths will then be twice the sheets width plus the profile width measured from one slot bottom to bottom and in total range from 220 to 2000 mm. A roof may easily be covered either completely or partially with the invisible solar panel technology by multiplying the single solar panel by parallel mounting, side by side. Such solar panels may be oriented perpendicular to the roof ridge or along the roof ridge and internally connected for fluid transport in series connection or parallel connections or combinations hereof.
The dimensions of the fluid transferring profiles are determined by the cooling medium chosen to be a liquid or a gas. In the event air is elected the system is simplified, since the triangle list as a profile transports gas of ˜1:800 density to capture the heat in the house. The channel in the list must be several times greater than if a liquid was transported.
The relatively lower attainable temperature of the circulated fluid obtained through the invention herein presented as compared to conventional solar panels, will be suited to energy accumulation systems with large thermal mass as for example a cast concrete floor with built-in energy carrying tubing, walls constructed of stone or in combination with concrete and built-in energy carrying hoses, buildings with central heavy building structures with built-in energy carrying tubing and light outer walls. Alternatively in combination with a heat pump the effective temperature may be increased to more than the fluid temperature leaving the invisible solar panel system.
In many countries it is normal to use non-organic fibre mats or porous plates for thermal insulation of building structures. In some regions polystyrene based air bubble foam sheets for the same purpose or even reflective foil insulation are widely used. These insulation components can be performed with varying density and physical dimensions for obtaining properties suitable for the isolation of various designs. It will be obvious to design and use relatively hard insulation panels for this invention so that the plates are aligned similarly to the underside of the liquid-cooled climate-screen interfaces. This reduces total height and thickness etc, plus reduces the number and size of cavities and should be able to eliminate cold bridges, etc. In some cases, such insulation panels laminated with the heat conveying surfaces facilitate installation.
Optimization of surface ability to absorb the energy from the sun irradiation depends entirely on the colour and surface characteristics. Generally, darker surfaces absorb energy much better than the bright surfaces.
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It will be obvious to anyone of technical skill that combinations of the above-mentioned structures in other ways than described herein can be made and such combinations are within the scope and spirit of the invention as defined in the appended claims. Further, the choice of air, water-based or other liquid as heat transporting media will depend on actual conditions and considerations and is also within the scope and spirit of the present invention, but being obvious for a man skilled in the art it will not be described herein. However, this will not change the nature and principle of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| PA 2007 01795 | Dec 2007 | DK | national |
| PCT/DK2008/000022 | Jan 2008 | DK | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DK2008/000368 | 10/20/2008 | WO | 00 | 12/27/2010 |
