AU2009290135A1 - Method and apparatus for solar energy assisted heat exchange - Google Patents

Description

WO 2010/025507 PCT/AU2009/001146 1 METHOD AND APPARATUS FOR SOLAR ENERGY ASSISTED HEAT EXCHANGE RELATED APPLICATIONS This application claims priority to Australian Provisional Patent Application 5 No. 2008904586 in the name of Chimera Innovations Pty Ltd, which was filed on 3 September 2008, entitled "Method and Apparatus for Solar Energy Assisted Heat Exchange" and the specification thereof is incorporated herein by reference in its entirety and for all purposes. FIELD OF INVENTION 10 The present invention relates to heat exchange. In one form, the invention is suitable for providing heated and cooled air for domestic and commercial use, however, it is to be appreciated that the invention is not limited to that use, only. BACKGROUND Buildings such as domestic dwellings, commercial office space, factories, 15 shops, and the like, have traditionally been heated to help maintain a comfortable temperature within when external ambient temperature is lower than desired. Many current methods of providing heat rely on consuming valuable natural resources, for example through electricity, or directly with oil, gas, and wood for instance. Using such resources to provide heat energy also leads to an increase 20 in carbon emissions that may have a negative effect on the environment, Alternative energy sources are being sought to alleviate reliance upon these resources. Solar energy is highly desirable as an alternative energy source, however, exploiting it is limited by current technology. A number of systems attempting to 25 harness solar energy for domestic and commercial space heating applications exist. Examples of existing products include the Sun Lizard Solar Climate Control System (www.sunlizard.com.au), ClearDome Solar Forced Air Heaters (www.cleardomesolar.com), Sunwarm Air (www.sunwarm.com), and Cansolair Solar Max (www.cansolair.com). Many current art solar air collector systems can 30 be characterized as a box like structure with a transparent lid, The transparent lid allows light through whilst the box like structure is used to absorb and trap the sunlight. Generally the box structure is black to maximise energy absorption. Air flow through or over the box structure harvests the heat energy. Although such WO 2010/025507 PCT/AU2009/001146 2 solar collector systems exist, the market has been reluctant to widely embrace the technology for various reasons including restrictive costs, excessive weight, bulkiness, and poor aesthetics. A major disadvantage of the current art is related to cost. Systems are 5 typically complex in design and hence expensive to manufacture. Costly materials, complicated fabrication techniques and difficulties during installation of systems large enough to be effective all lead to prohibitive initial outlay and long pay-back periods for the end user. This often makes their purchase and use uneconomical. Efforts by manufacturers to offset such limitation leads to a 10 general under sizing of existing solar air heaters. The systems are undersized in order to keep the price low. Whilst this practice does keep the price down it also directly results in an inadequate available surface area for solar energy collection and, therefore, the net heat output is typically inadequate for the requirements of the building. As a direct result, existing solar air heaters supply insufficient heat 15 to adequately heat a building or, if they are large enough, they are far too expensive for widespread uptake. In both cases existing solar air heaters represent poor value for money. Current art solar collector systems that are large enough to heat effectively are usually bulky and unsuitable for on-site assembly and installation by building contractors or the do-it-yourself handyperson. This 20 makes such systems costly to Implement. A box type structure Is relatively complex to manufacture. For example, a metal structure will typically require folded, welded or an otherwise joined together base, sides and end walls with sufficient strength to support a transparent lid of glass or plastic that is robust enough to be weatherproof. Such complexities do 25 not lend themselves toward high volume or automated manufacture. W02006/031108 describes a solar collector system comprising multiple plates and a convoluted liquid path through zig-zag channels. So called turbulence members provide the path in order to slow fluid flow and maximise heat transfer. US Pat, No. 4262657 teaches that multiple chambers, with a preferably bonded 30 lid, that traps radiation can effectively transfer heat to an airstream as it passes between a porous plate joining the layers. Many other solar collector systems also use barriers such as baffles, fins, projections, or inserts to throttle the flow of fluid, typically air, through the system in an attempt to increase heat transfer to WO 2010/025507 PCT/AU2009/001146 3 the flowing fluid stream. These types of systems require larger fluid drive mechanisms such as fans, accumulators, blowers or pumps to provide necessary fluid flow to account for pressure drops that arise from restricted flow. Doherty in PCT application W02007/100819 informs us that systems that trap heat within an 5 enclosure, much like a greenhouse, are less efficient partly because incoming cold air is allowed to mix with the heated air in the solar air heater. Such mixing decreases the average temperature of the air in the heater and, thus, reduces the overall efficiency of the heater, However, Doherty's system where the enclosed space within the device housing is divided into at least two essentially isolated 10 sections by a partition, also uses a convoluted fluid path. Whilst harnessing solar energy for heating is desirable, it may also be necessary to insulate dwellings against excessive solar energy transfer. Materials such as multi-walled polymer sheeting (US Appl. No. 11/463927) have been developed with U-values less than or equal to 2.3W/m 2 K. This material 15 transmits light but stops re-radiation and heat losses. Some solar heating systems, such as the SolarVenti@ solar air collector (www.solarventi.com), use multi-walled polymer sheeting as a lid. A multi-walled extrusion has the advantage over a single walled plastic or glass lid in that it is a superior insulator (insulation properties being provided by a static air gap between the layers of 20 plastic), thus minimising heat losses to the outside ambient air and therefore improving the overall efficiency of the solar air heater. Polymer sheets also weigh considerably less than glass of similar area and structural integrity. However, such systems employing bulky housings remain costly and difficult to manufacture. Another consequence of excessive solar energy transfer occurs when 25 temperatures inside buildings or dwellings remain high after daylight ends. Air conditioning, evaporative coolers, blowers, fans and the like are used to reduce internal temperatures but these may be expensive or inconvenient to run constantly. Another aspect of indoor environments contributing to comfort and 30 suitability for inhabitation is that of ventilation. Atkin et al. in PCT application W01997/015793 teaches buildings of all types, even when adequately heated, commonly suffer from the effects of condensation and fungal growth, the source of which can be seriously detrimental to the health of the occupants. An WO 2010/025507 PCT/AU2009/001146 4 increased level of humidity can occur from everyday activities and the moist air becomes trapped within a building through the common use of modern insulation techniques, double glazing and draft stripping. Although this increases the thermal efficiency of the building, it allows little or no natural ventilation. Buildings 5 now lack ventilation as people improve the sealing of windows, doors and the like to conserve energy. These conditions produce a generally unhealthy environment and may lead to chronic respiratory disorders such as asthma as well as causing structural damage to the building itself. According to Environmental Protection Agency (EPA) studies, human 10 exposure to indoor air pollutants may be two to five times -- occasionally more than 100 times -- higher than outdoor pollution levels. Indoor air pollution, or Sick Building Syndrome, is among the EPA's top four environmental risks to public health. Aforementioned closed loop systems, including air conditioning units, do 15 not promote ventilation. There remains a need for a high performance, low cost, light weight, steady flow and flexible solar energy heating, cooling and ventilation solution that is easy to manufacture and install. Throughout this specification the use of the word "inventor" in singular form 20 may be taken as reference to one (singular) Inventor or more than one (plural) inventor of the present- invention. It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the 25 identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor's knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the 30 prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein.

WO 2010/025507 PCT/AU2009/001146 5 SUMMARY OF INVENTION It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems. 5 in a first aspect of embodiments the present invention provides a method of heating a fluid utilising solar energy, the method comprising the steps of: absorbing solar radiation into a first structural portion; absorbing radiation that is re-emitted from the first structural portion into a second structural portion located proximate the first structural portion; 10 guiding a fluid flow between the first and second structural portions. Preferably, the step of guiding further comprises exchanging heat between the fluid and the first and/or second structures by means of convection. Also, it is preferred that the first structural portion comprises a low thermal mass absorbent medium. 15 In a preferred form, the method may further comprise the step of: insulating the exchange of heat between the fluid and the first and/or second structural portions by locating a third structural portion peripherally with respect to the first and second structural portions. In another aspect of embodiments the present invention provides 20 apparatus for heating a fluid utilising solar energy, the apparatus comprising: a first structural portion comprising a medium adapted for absorbing solar radiation and re-radiating energy substantially immediately; a second structural portion located proximate the first structural portion which is adapted for absorbing re-radiated energy from the first structural portion; 25 wherein the first and second structural portions form a fluid flow path for fluid to exchange heat energy between the fluid and the first and/or second structural portions. Preferably, the apparatus further comprises a third structural portion located peripherally about the first and second structural portions and adapted to insulate the exchange of heat energy between the fluid and the first 30 and/or second structural portions. The second and third structural portions may be adapted to be at least partially transparent to solar radiation. In a particularly preferred form at least the second and third structural portions form an integral WO 2010/025507 PCT/AU2009/001146 6 structure and are comprised of the same material, It is also a preferred features that the first structural portion forms a central core of the integral structure. In another aspect of embodiments, the present invention provides a method of exchanging heat for use in providing temperature control of an 5 enclosed environment, the method comprising the steps of: communicating radiant energy between the exterior and a core of a multi walled panel; channelling fluid through the multi walled panel; exchanging heat between the fluid and a centrally disposed high radiant 10 energy absorbent portion of the core of the multi walled panel, wherein the absorbent portion is adapted to re-radiate energy upon being heated by one of the fluid or radiant energy communicated from the exterior of the panel. In yet another. aspect of preferred embodiments the present invention provides a method of fabricating a heat exchanger, the method comprising the 15 step of extruding a multi walled structure to form: a centrally disposed high radiant energy absorbent portion adapted to re radiate upon being heated, and; cavities adjacent the centrally disposed portion adapted for allowing a fluid to pass there through and exchange heat energy between the fluid and the walls 20 of the cavities. In another aspect of embodiments there is provided, a method of heating a fluid utilising solar energy, the method comprising the steps of: exposing a first medium t6 solar radiation; capturing radiation that is re-emitted from the first medium in a first region 25 proximate the first medium; guiding a fluid flow through the first region. The first medium may comprise a low thermal mass absorbent medium. The step of capturing may comprises the step of: absorbing the emitted radiation from the first medium into a second medium wherein the second 30 medium comprises material at least partially transparent to solar radiation, but non-transparent to the emitted radiation ; and guiding the fluid flow through both the first region and a second region proximate to the second medium.

WO 2010/025507 PCT/AU2009/001146 7 The second medium may comprise multiple channels, where the step of capturing may further comprise of the step of: absorbing the emitted radiation from the second medium into a second medium external channel wherein the multichannel second medium comprises material at least partially transparent to 5 solar radiation, but non-transparent to the emitted radiation; and guiding the fluid flow through both the first region, a second region and third region proximate to the second medium external channel. Preferably, the methods as disclosed herein may further comprise the step of circulating the fluid to at least one of: 10 a domestic environment; a commercial environment; an environment occupied by humans and/or animals an environment occupied by plants and/equipments, Furthermore, the fluid may comprises one or a combination of: 15 air; a natural gas; a natural gas mixture; a synthetic gas; a synthetic gas mixture 20 water. In another aspect of embodiments described herein there is provided apparatus for heating a fluid utilising solar energy comprising: an inlet for guiding solar radiation into the apparatus; a first medium adapted for absorbing solar radiation and re-radiating the 25 solar radiation substantially immediately. The inlet may be adapted to be at least partially transparent to solar radiation. Alternatively, the inlet may be adapted to be substantially reflective of the re-radiated solar radiation. The apparatus may further comprise guide means for guiding a flow of fluid through the apparatus. Preferably, the apparatus may 30 further comprise circulation means for circulating the fluid to at least one of: a domestic environment; a commercial environment; an environment occupied by humans and/or animals.

WO 2010/025507 PCT/AU2009/001146 8 In yet a further aspect of.embodiments disclosed herein, there is provided a fluid heat exchange system for use in providing temperature control of an enclosed environment comprising: at least one multi walled panel adapted for communicating radiant energy 5 between the exterior and a core of the panel and configured in cross section to provide at least one channel allowing movement of fluid through the panel, a centrally disposed high radiant energy absorbent portion adapted to re-radiate upon being heated wherein the moving fluid exchanges heat with the centrally disposed high'absorbance portion. 10 Preferably, the multi walled panel comprises a polymeric material that is highly transmissive of radiant energy and also thermally insulating. The absorbent portion may comprise one or a combination of: thin metallic strips disposed along the length of the panel; thin metallic strips coated with absorbent paint disposed along the length 15 of the panel. internal cavities of the panel with metallic coating; the panel coated with solar energy absorbent material; thin plastic opaque strips disposed along the length of the panel internal cavities of the panel with an opaque plastic coating or surface 20 The multi walled panel may further comprise at least one insulating channel adapted to confine radiant energy to the fluid flow channels such that heat exchange is optimized between the fluid and the absorbent portion. The multi walled panel may be adapted to connect to at least one other multi walled panel to provide a heat exchange system that is modular and 25 scalable. The multi walled panel may also be adapted to conform to the form of building it is installed upon. Alternatively, the multi walled panel may be adapted to form a portion of a building. The heat exchange system as disclosed in preferred embodiments may be adapted to provide one of: 30 heating of the enclosed environment by, primarily during daylight, transferring heat from solar radiation external of the panel to the fluid flowing through the multi walled panel, and; WO 2010/025507 PCT/AU2009/001146 9 cooling of the enclosed environment by, primarily at night, transferring heat from fluid flowing through the multi walled panel to the absorbent portion to subsequently be radiated externally of the panel. Further, the system as disclosed by preferred embodiments may further 5 comprise one or a combination of: a manifold for collecting outlet air from the multi walled panel; a ducting system for distributing the outlet air to the enclosed environment; a controllable fan system for' switching control of the air flow into the enclosed environment. 10 Other aspects, embodiments and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention. In essence, embodiments of the present invention stem from the counterintuitive realization that a multi walled structure, hitherto used generally to 15 perform an insulating function by way of providing a static air gap (for example between layers (walls) of polymer), can form a flow path for moving fluid and thus provide a means of transferring heat energy between the multi walled structure and the moving fluid where the predominant mechanism of heat energy transfer between the structure and the fluid is convection by way of contact between the 20 moving fluid and the structure and the predominant mechanism of energy transfer between the structure and an energy source/drain is radiation. In a practical application of this realisation, embodiments of the present invention may comprise a multi walled panel member configured to form channels for fluid flow over a high radiant energy absorbent portion of the panel that has 25 low thermal inertia with an ability to substantially instantly re-radiate absorbed heat and likewise the multi walled panel can be configured to a structure for containing and/or isolating radiant energy received from an external source such as solar to the absorbent portion and also provide a "reverse cycle" heat exchange function by allowing the re-radiating *of heat energy from the high 30 radiant energy portion that is transferred thereto from passing fluid. In preferred forms the multi walled panel comprises an extrusion which may insulate a collector area and the multi layers provided by the walled structure allow simple manufacture that both insulates and gives large surface area for WO 2010/025507 PCT/AU2009/001146 10 heat energy exchange. The configuration of surface area in a number of actual configurations may generally be seen as a honeycomb structure which covers any number- of configurations of the walls of the structure. Surfaces of this honeycomb immediately adjacent an inserted structure, preferably of strips (which 5 may be metal or plastic or other material but more important is that the colour of the strips is dark or black for efficient absorption and/or re-radiation of energy) absorb and re-radiate energy. In preferred embodiments during the passage of fluid, for example air, there is no mixing of hot/cold fluid given that the structure is formed to provide a gradual passage of fluid for the exchange of energy. 10 When heating the fluid, the main mechanism for the passing fluid (for example air) to receive Its energy is convection via contact with the surfaces of structure that has captured the majority, if not all of the energy that may pass into the structure. Preferably, a multi walled structure in accordance with preferred 15 embodiments comprises at least two secondary surfaces for capturing re-radiated energy from the core of the multiwalled structure. In a particularly preferred embodiment, it has been found that three such secondary surfaces may be optimal. In another preferred embodiment, there is use of at least two multi walled 20 extrusions where one is essentially black for high absorbance and the other is predominantly clear /transparent in colour. Placed adjacent each other these two different coloured extrusions may act to collect radiant energy from the external atmosphere such as by solar radiation which may pass through the 'clear' extrusion practically without any absorption and the energy is collected by the 25 'black' extrusion for heat exchange with fluid passing through cavities within the combined structure. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an isometric view of two multi-walled panels in accordance with a preferred embodiment; 30 Figure 2 shows cross-sectional schematics of five alternate configurations of a multi-walled panel as shown in figure 1; Figure 3 shows two alternate forms of installed multi-walled panels in accordance with preferred embodiments; WO 2010/025507 PCT/AU2009/001146 11 Figure 3a illustrates a modified external profile for a multi-walled panel in accordance with a preferred embodiment for installation on a flat roof; Figure 4 shows a schematic of a multi-walled panel and insulation panel in accordance with another preferred embodiment; 5 Figure 4a shows a schematic of a multi-walled panel in accordance with another preferred embodiment; Figure 5 shows a schematic of a multi-walled polycarbonate panel, an insulation panel, and a manifold in accordance with a further preferred embodiment; 10 Figure 6 shows a schematic of a solar energy heat exchange apparatus capturing solar radiation in accordance with a preferred embodiment; Figure 7 shows a schematic of air flow through a solar energy heat exchange apparatus according to yet another preferred embodiment; Figure 8 shows a schematic of an installed solar energy heat exchange 15 system in accordance with another preferred embodiment; Figure 9 shows a schematic of a solar energy heat exchange system mounted on an angled roof in accordance with another embodiment; Figure 10 shows a schematic of a solar energy heat exchange system mounted on a flat roof in accordance with yet another embodiment; 20 Figure 11 shows a schematic of a solar energy heat exchange system mounted on a wall in accordance with another embodiment; Figure 12 shows a schematic of a solar energy heat exchange system mounted on a carport in accordance with a further embodiment; Figure 13 shows a schematic of a solar energy heat exchange system with 25 fan and ducting in accordance with another embodiment; Figure 14 shows a chart mapping ambient and roof surface temperature over time; Figures 15 to 19 illustrate the performance of various embodiments of the present invention. 30 DETAILED DESCRIPTION OF PRESENT INVENTION The present invention relates to a high performance, low cost and modular heating, radiant cooling and ventilation system that captures and transfers solar WO 2010/025507 PCT/AU2009/001146 12 heat energy and provides radiant cooling to a fluid medium. The fluid, for example air, is then distributed to areas where heating or cooling is desired. A first embodiment of the present invention incorporated into a domestic or industrial heat exchange system comprises the following components: 5 e A multi-walled panel that may be manufactured as a plastic extrusion and preferably made from polycarbonate, polyvinylchloride, or other suitable polymeric materials * An insulating component as a part of the multi-wall panel that may be a layer of air. Another option is to have an insulation panel that 10 may be made from polystyrene with an aluminium foil layer or Kingspan T M insulation. * Multiple strips that run the longitudinal length of the multi-walled panel and are made of material and/or colour which are known to absorb radiant energy. Such material may be metal and be dark in 15 colour (e.g. black) * A manifold that may be manufactured as a plastic extrusion, sheet metal or made from polycarbonate or other suitable materials * Ducting and fan that incorporates a means of drawing or propelling air 20 * Controller system which consist of a temperature controller for turning the fans from the solar heating/cooling/ventilation on and off. * Roof flashing to seal the solar heater/cooling (ie heat exchange component) onto the roof of an installation. Figures 1 and 2 show isometric and schematic cross-sectional views of 25 embodiments of a multi-walled panel 1 component or sheet. The nmulti-walled panel 1 Is preferably a one piece integrated structure comprising 2 or more walls. In a further embodiment, the structure will have 3 to 6 walls, separated by parallel ribs that run the full extent, either width and/or length of the panel sheet. The spacing between the ribs creates a plurality of channels which allow the 30 movement of fluid, for example air. In one embodiment, the total thickness of the structure is in the range of about 10mm to about 150mm. In a further embodiment the thickness of the structure is in the range of about 20mm to about WO 2010/025507 PCT/AU2009/001146 13 80mm. In another further embodiment the thickness of the structure is in the range of about 40mm to about 60mm. In one embodiment the thickness of the. channels is in the range of about 1mm to about 100mm, and in another further embodiment the thickness of the channels is preferably in the range of about 5 5mm to about 40mm. The multi-walled panel, 1, structure may be made of an extruded plastic, for example polycarbonate, acrylic, or styrene, and will ideally have a high light transmission between a range of about 40% to about 100%. The person skilled in the art would appreciate that other suitable materials may be used which would 10 provide -similar functional benefits in accordance with embodiments described herein. Figure 3 shows two examples of installations of. the multi-walled panel, 1, having an upper wall exposed to incident radiant energy, for example, solar radiant energy. Incident light, 20, is both refracted into the sheet and reflected 15 away from the sheet by the upper wall. In the flat configuration the reflected light may be bounced back into the atmosphere. In the zig-zag configuration the reflected light may be bounced into the upper wall again. By having the top surface in a zig-zag shape, the reflected light is given a "second chance" to be transmitted through the wall. Furthermore the zig-zag arrangement can form the 20 basis of a useful alternate structure that allows for installation on a horizontal surface which would obviate the need to install the unit with an inclined frame component. In this respect, one embodiment of the invention is to design an extemal profile to suit mounting on a flat roof. One solution for installation on a flat roof is to angle a panel used for capturing solar energy towards the sun. For 25 example, the panel may be mounted on a frame so that it is between 30 and 60 degrees to the horizontal, angled, for example, towards the north in an installation for the southem hemisphere. This angle ensures adequate performance in capturing appropriate levels of solar energy. This particular mounting situation may require the additional expense of a metal frame to securely hold the panel at 30 the appropriate angle. Also, due to the angle of the panel, the panel may be potentially subject to high wind loads so the frame needs to be quite robust. The embodiment shown in figure 3a shows a modified extemal profile on the panel to allow the solar panel to efficiently harvest solar radiation whilst WO 2010/025507 PCT/AU2009/001146 14 mounting the panel itself horizontally directly onto a flat roof. Because no frame is required this is a much simpler and more cost effective installation. The angled outer surface also allows the radiation to be efficiently harvested compared to a standard flat panel. 5 With respect to the composition of the panel or sheet, clear polycarbonate may be chosen as a material due to its excellent radiation transmission performance, superior insulating performance (compared to some other plastics and glass), low cost, ready availability in suitable sizes, robustness (eg hail resistant), UV resistance, light weight and stiffness (no need for supporting ribs 10 that may block direct sunlight). The multi-walled panel, 1, upper wall may also be coated- to help performance in the preferred embodiments. A hydrophobic coating on the external surface reduces the surface tension of polycarbonate and increases the contact angle of water to the sheet. This causes larger droplets to form and wash away dirt, maximising surface area for solar light transfer. A 15 hydrophilic coating on the inner surface reduces the formation of condensation droplets by increasing the surface tension of the sheet and decreasing the contact angle. As a consequence, a thin mist of water will form on the inner surface of the sheet, which will not drip and will not affect the excellent light transmission of the material. An example of this material is Lexan@ Thermoclear 20 that is marketed by Sabic Innovative PlasticsTM. Figure 4 shows an embodiment of the multi-walled panel, 1, and a high radiant energy absorbent portion, preferably a black strip, 2. The black strip components, 2, may run the length of the channel and are made of material and/or colour which are known to absorb solar radiant energy, thereby increasing 25 the heating of the air as it passes through the channels, 5. The harvesting of heated air is being drawn directly from the channel, 5, directly above and below the black strip, 2, Material suitable for solar radiant energy absorbance is selected from a group comprising one or more of metal, surfacing said partitions with metal or a 30 metal-based paint, colouring the surfaces of said partitions a dark colour (e.g., black). Alternatively the black strip, 2, may be replaced by an interface wall, shown at 2a in figure 4a, of the multi-walled panel, 1, that is, the interface wall is pigmented or coated to maximise solar energy absorption. The interface wall is WO 2010/025507 PCT/AU2009/001146 15 preferably formed as an integral part of the multi-walled panel rather than as a separate strip. The pigment may be added as part of a co-extrusion process during manufacture of the multi-walled panel. Another option is to have the panel coated with solar energy absorbent material, the coating blocks near infrared light 5 but lets high levels of visible light through. An example of such material is the Lexan thermoclear solar control IR. To prevent heat loss from the multi-walled panel, the bottom, 4, and the top, 3, air cavity channels of the multi-walled panel acts as insulation by containing air, which is preferably static to increase the insulating properties. It Is commonly known in the art that air is a good insulator. 10 Many other insulation methods were considered during development, however, based on performance and cost the above was the preferred embodiment. Alternative insulation panels considered are materials with a minimum insulation rating of R1.0. An example of such material is aluminium foil board that 15 comprises polystyrene and aluminium foil. Foil coated insulation is a readily available and low cost product used in the building industry. Examples of these materials include Sisalation@ (www.sisalation.com), Insulbreak@ from AIR-CELL Innovations Pty Ltd (www.air-cell.com.au), Silverbatts Foil Insulation (available from http://buybuildingsupplies.com.au/insulation-silverbatts-c-1 5_1 49.html), 20 Kingspan Kooltherm@ from Kingspan and R-Shield foil insulation (available from http://buybuildingsupplies.com.au/insulation-rshield-foil-insulaltion-c-5_1 587.html). In one embodiment the foil will be black rather than silver due to the desire to absorb heat rather than reflect it. To achieve the desired colour the foil may be painted or chemically treated, for example anodised. 25 Figure 5 shows an embodiment of the current invention, which comprises a solar energy heating apparatus, 6, in cross-section with a multi-walled panel, 1, with black strip, 2, and a manifold, 9, The manifold 9 and panels 1 are sealed by silicon or seals, 7, which are made of a suitable material, for example rubber or silicon. The manifold, 9, may be moulded or extruded or folded and made of a 30 material capable of withstanding temperatures in excess of about 120'C. Examples of such material are Polycarbonate and steel. In another embodiment the manifold is made from a material that has insulation properties. In another embodiment the manifold is intemally insulated. In one embodiment the manifold WO 2010/025507 PCT/AU2009/001146 16 is painted or manufactured in black, The cross-sectional dimension of the manifold, 9, in a rectangular shape can have the width in the range of about 40mm to about 300mm and the length in the range of about 50mm to about 400mm. In a further embodiment the width in the range of about 50mm to about 5 150mm and the length in the range of about 150mm to about 300mm. .The volume within the manifold should be large enough to ensure even and consistent fluid flow. Additional features, not shown, can easily be included into a manifold, 9, to keep the present embodiment very simple as would be understood by a person 10 skilled in the art. For example; lugs for mounting the heater unit onto the roof, features to facilitate quick assembly, quick attachment to roofing flashing, simple attachment of ducting, 10, as shown in figure 13. An additional benefit of the plastic manifold, 9, is that it can be manufactured in a variety of colours and with some external design features for optimal aesthetics. 15 In a further embodiment, the black strips, 2 may be fully integrated into the multi-walled panel, 1, as a very simple one-piece moulding or extrusion. This would further simplify the product significantly and therefore further reduce the manufacturing cost and post moulding processing and assembly requirements. The method of manufacture would 'be to create a customised moulding or 20 extrusion tool(s) capable of moulding the top two layers of the assembly shown in figure 4a in a transparent plastic, such as clear polycarbonate, and the bottom three layers (including the interface wall, 2a) in an opaque, ideally black, plastic material such as polycarbonate. It is a known practice to mould plastic parts in two or more separate materials simultaneously such that one section of the part is 25 in the first material and the second section of the part is in a different material with different properties. Whilst the aforementioned-materials have been described for use in the present embodiment, it would be apparent to a person with ordinary skill in the art that alternative materials with similar characteristics may be substituted. 30 In one embodiment, a multi-walled panel, 1, may have at least two separate chambers that run along the length of the panel. A cross-section and longitudinal section of an exemplary panel 1 suitable for a solar energy heat exchange apparatus, 6, is shown in Figure 6, Incident solar radiation, 20, WO 2010/025507 PCT/AU2009/001146 17 penetrates the top layer of the multi-walled panel, 1, and hits the black strip, 2, of the multi-walled panel, 1. This radiation is absorbed by the black strip surface, 2. This black surface heats up very quickly and almost immediately re-radiates the energy as long wavelength radiation, 19. This long wavelength radiation, 19, is 5 trapped by the top and bottom layer of the multi-walled panel, 1, capturing the heat energy to warm the passing fluid stream, 18, for example air. To obtain maximum performance from this solar energy heat exchange apparatus, 6, the air is drawn through the chambers and into the manifold, 9, i.e. the top surface acts like a lid and insulates against the hot air escaping. The bottom surface of the 10 multi-walled panel, 1, also serves to slow dissipation of heat energy. The principle of operation of an embodiment of the current invention is shown in Figure 7. Incident solar energy, 20, penetrates the top layer of the multi-walled panel, 1, is absorbed by the black strip, 2, and re-radiated and absorbed into both the upper and lower cavities 5, as best shown in figure 4, of 15 the multi-walled panel, 1. Fluid, for example fresh externally sourced air, 21, is drawn into the lower cavities 5 and the captured solar energy is transferred to the air, 21, by convection. This facilitates a rapid and effective heat transfer to the air, 21. The solar heater is extremely efficient as it is providing heating of air in a gradual manner. The cool air gradually heats up as it moves along the channel 20 from one end (the entrance point) to the other end (the exit) of the polycarbonate channels. It is to be noted that the panel may be mounted in any orientation including horizontal, so there is not necessarily a bottom or top, furthermore, It is preferable to use a fan to force convection, and not rely on a natural convection of warm air rising. A fan may be suitably placed to either push air into the panel or 25 pull air into the panel. The heated air, 21a is drawn into the manifold, 9, and distributed to the building via ducting (not shown). This compares favourably to other solar heaters (which typically have a relatively expensive metal housing), Current art that relies on the metal housing being heated to contribute to energy transfer may take considerably longer to heat the system and transfer the same 30 amount of heat as the present embodiment. Such metal housing is also subject to faster heat loss during periods of brief sunlight. Due to the high thermal efficiency of the present embodiment it is able to harvest heat energy even on cold days. Fresh air may also be considerably cleaner than air recirculated from WO 2010/025507 PCT/AU2009/001146 18 either the building or the roof cavities that may be prone to contaminants such as dust, animal fur or excrement, fibreglass, asbestos or other pollution. Applying positive heated air pressure to the building may help to expel moisture within the building that can lead to unwanted condensation and/or mould. 5 Figure 8 shows an example heat exchange system comprising the solar energy heating apparatus, 6, ducting, 10, and fan, 7. This arrangement is easily customised for application to existing structures or during building of new structures. As such a typical system, in accordance with preferred embodiments 10 comprises a temperature controller for turning the fans from the solar heating/cooling/ventilation on and off. The temperature controller of the present embodiments may be electrically connected to a temperature sensor(s) for measuring the temperature of the air coming out of the solar air heater/cooler. The temperature reading of the sensor is then electrically relayed. to the 15 temperature controller. The temperature controller then electrically relays a signal to the fan(s) to turn the fan(s) on or off once preset temperatures are obtained. A temperature controller of the present embodiments may be, for example, a self contained electronic device comprising, for example, a microchip, or a personal computer. The temperature controller of the present embodiments may also 20 serve other functions such as displaying the temperature in the processed air, room and/or outside the building or sending data to a data recording device. The temperature controller may also be used to, for example, adjust settings (e.g., temperatures at which the fan(s) turn on/off). Similar air transfer products are supplied by HRV (www.hrv.com.au) in their ventilation and heat recovery system. 25 A further embodiment of the present invention may use a second manifold to draw cool air from the building to be heated. Figure 13 shows an example of the system's application in this situation. Warm airflow, 21 a (direction shown by the arrows). is circulated from the house, filtered, drawn through the solar air heater and back into the house. ' A sensor (not shown), such as a thermostat, 30 measures the air temperature and controls the rate of airflow, via a fan, 7, to achieve a desired temperature inside the house. A further embodiment may draw either extemal air, air from the building (inside the roof cavity, inside or under the building), or a combination of all, into WO 2010/025507 PCT/AU2009/001146 19 the solar energy heating system, this can be achieved by control valve and damper system (not shown). Sensors (not shown) measuring external and internal temperatures may determine the most favourable source of air in order to achieve the desired temperature. These sensors may also be used to trigger the 5 heating system below a set temperature and stop the heating system once a desired temperature is reached. A further embodiment is to draw air from a roof cavity, as this air may be pre-heated when compared to the external air or internal building air temperatures. The roof surface of a building can act as a large solar collector, 10 heating the roof cavity of a building even on cold days. The air inside the roof cavity has been used to heat a building with moderate success (one example of such a system is the heat recovery ventilator supplied by HRV Australia, www.hrv.com.au), however the net heat output is limited by the low efficiency of the roof as a solar collector, high thermal losses to ambient (due to drafts, wind, .15 rain, lack of insulation on the roof etc) and the house design itself. For example, a roof made of a light colour corrugated iron, which reflects a significant portion of the solar energy, with insulation material on the underside of the roofing material ("sarking") will not allow sufficient heat energy into the roof cavity for this heat to usefully warm a house. In alternative scenarios, were the roof surface is black, 20 the internal roof cavity temperature may be significantly warmer than the ambient temperature conditions. In this scenario it may be beneficial to use this pre heated air as the input into the Solar air heater. This will boost the output temperature of the air from the solar air heating system The present embodiments described above have several advantages over 25 current art solar heating systems. A major advantage is the cost benefit that may be achieved during manufacture and subsequently passed on to the customer. Lower initial outlay and no ongoing running costs represent a greater value for money. Many current art systems use metal frames (eg Al, mild steel). These are relatively heavy as well as difficult and costly to fabricate in high volumes. 30 Metal frames may also dissipate captured solar energy more quickly thereby reducing overall efficiency. Due to the high thermal efficiency of the present embodiment it may be produced in a more compact size. The fabrication techniques available for WO 2010/025507 PCT/AU2009/001146 20 producing the described embodiment allow for the system to be adapted for use in industrial, commercial or retail applications. The system is easily scalable to suit varied requirements of these applications. Figures 9, 10, 11, and 12 show the versatility of a preferred embodiment of the present invention by examples of 5 different building applications. The system of preferred embodiments is unique in that the panel can be joined together to form a continuous wall or panel. This leads to the benefit that it can be used as an actual roof or wall material rather than a product that sits on top of the roof of a building. 10 This may take the form of a roof of a building, or it could take the form of a roof of a non-enclosed structure such as a *patio or carport, or alternatively it could take the form of a wall of a building or even a fence. The benefits include: * Reduced cost of roofing or wall materials since the panel acts as the 15 roof/wall * An ability to design a solar heater into a building or structure so that it is not obvious that it is even a heater. For example a fully integrated wall or roof would not look like a solar heater at all which would be beneficial in some circumstances 20 0 The system could be integrated into a fence so that it forms a dual purpose In addition, the ease of manufacture allows for units to be made into modules ranging in size, For example, size may range from 1m 2 to 20m 2 and above. In essence the present embodiments stem from the realization that the 25 solar panels can be combined into one extruded multi-walled polycarbonate sheet. The multiwall sheet can be formed simply but not limited to one or more of the following: - Co-extruded - Painted 30 - Black strips added - Additives added to the plastic to obtain the benefits required to obtain the performance of heating/nightsky cooling and ventilation.

WO 2010/025507 PCT/AU2009/001146 21 In its simplest form the solar panels require the assembly of the processed multiwall sheet to the manifold. Total assembly of the solar panels comprises: - Processed multiwalled sheet 5 - Manifold - Insulation in the manifold - C section to secure the side to the building - Mesh filter to prevent particles or vermin entering the multiwalled panel 10 - Screws and seal/silicon to hold it all together An exemplary heat exchange system for a house may comprise the following: " Solar panel assembly as described above * Insulated ducting 15 0 Flow controlled fans e Ceiling diffusers * Zoning controller * Thermostat Controller The aforementioned additional components are available off the shelf from 20 many suppliers. These are described in more detail at www.westaflex.com.au Multiple units may therefore be joined together to provide a tailored solution for specific customer needs. Another advantage of the lightweight structure of the preferred multi walled panel is that it is relatively easy to install. Fabrication techniques, for example extrusion or moulding, allow for specifically 25 designed tags or anchor points to be incorporated and shapes that follow the contour of the mounting surface, for example a corrugated or tiled roof. These features help to keep assembly and installation costs to a minimum. Combining low cost plastic and low cost off-the-shelf products (multi-walled panel polycarbonate) gives rise to a system that is much cheaper to produce than 30 that of the current art products. Hence, a fast payback period for customers is obtainable. This means greater access to a product that not only reduces overall energy expenditure on, for example gas and electricity, it reduces the amount of WO 2010/025507 PCT/AU2009/001146 22 emissions and carbon footprint normally used for heating. The heating is completely solar powered and therefore requires minimal running costs. The present embodiment is therefore environmentally friendly producing no or very low greenhouse gas emissions for the life of the product. 5 The simplicity of the design also makes it easy to integrate with existing roof ducting heating devices such as the aforementioned HRV system. Figure 9 shows the concept in situ on the roof of a house. The solar heater is designed to be visually pleasing by: -- Minimising the profile of the heater; and 10 - Allowing the manifolds, 9, to be moulded or painted in a variety of colours to complement the existing roof colour Figure 10 demonstrates the principle of modularity and scalability. The manifolds, 9, are designed to 'plug' together to allow a greater area for solar collection. In a flat roof application, multiple units may be mounted at an angle to 15 maximise solar energy collection and achieve a desired pitch angle to facilitate water run-off. This may allow a user to maximise the heater performance for minimal additional system cost. A scaleable design caters to all users depending on the size and shape of the roof and number of rooms or area to be heated, Another advantage is the 20 system may be doubled in capacity for far less than double the total system cost. An additional benefit of modularity is that it may facilitate a reduction in manufacturing cost by allowing the manufacturer to manufacture a higher volume of modules (i.e. one system may consist of three or more modules), thus achieving economies of scale at a lower systems manufacturing volume. 25 Whilst there are many applications for this technology outlined above, some additional applications for this technology are available if it is integrated with existing Heating, Ventilation and Air Conditioning (HVAC) systems. Most buildings today have some type of HVAC system in operation. It is desirable for any complementary heating system to integrate with such systems in 30 order to minimise the incremental cost of installation of a solar heating system. Following is a description of a number of options for how the system may be integrated: WO 2010/025507 PCT/AU2009/001146 23 HVAC systems typically re-circulate air from a building through some type of heat exchanger (for heating and/or cooling purposes) and back into the building. A HVAC system normally must draw a portion of the return air from a fresh external air supply to ensure some fresh air is supplied to a building. One 5 possible application for the solar heat exchanger of preferred embodiments described herein is to provide heat just to this fresh air stream which may consist of 10% of the total volume of air circulated through the system. A second possible application for the solar heat exchange system of preferred embodiments described herein is to provide heat to a heat exchanger 10 which is located in-line with the existing air path. Air being circulated from the building would then be automatically heated in this additional heat exchanger. On days of significant solar radiation the air would be largely heated in the solar powered heat exchanger, thus reducing or even eliminating the load on the conventional heating system. Conversely on days of poor solar gain the 15 conventional HVAC system would operate as designed. A key advantage of this system is that the entire system operates seamlessly from a user's viewpoint. Solar energy is utilised to minimise the conventional heating requirements whenever it is available. The system described above uses an in-line heat exchanger. This heat 20 exchanger might be an air-to-air heat exchanger where air from the preferred solar heater system is used to raise the temperature of the heat exchanger then re-circulated to the solar panels. Air from the solar panels would not mix with the air from the building. Alternatively this heat exchanger may be a liquid-to-air heat exchanger. In this scenario water or some other suitable fluid may be used In the 25 solar heat exchange panels and used as a working medium to transfer the heat to the heat exchanger which in turn heats the air stream moving from/to the building. The systems described above work equally well on a domestic or industrial scale. Many domestic houses use a central heating system that is powered by gas or electricity. The preferred solar heat exchange system could integrate with 30 this. Similarly, many commercial buildings use a very large scale HVAC system which could be integrated with solar panels. Some existing HVAC systems already use a working fluid to transfer heat from a heat source (such as a gas or coal fired boiler) to the air stream which may WO 2010/025507 PCT/AU2009/001146 24 be located some distance away from the heat source. This working fluid may be water. In this scenario the solar heat exchange panels of preferred embodiments may be used to provide supplementary heat (or pre-heat) to the working fluid. Again this could be via an air-to-fluid heat exchanger or via a fluid-to-fluid heat 5 exchanger. Alternatively, the working fluid may be run directly through the solar panels described herein to provide some supplementary heating prior to entering the conventional heating source (such as a boiler). Some existing HVAC systems use heat to drive an air conditioning system (for air cooling). Typically this is achieved using an absorption refrigeration cycle 10 (for example the ammonia cycle). The panels of a preferred embodiment could be used to supply the heat energy to drive such a refrigeration cycle. This would provide free cooling energy which can then be used to cool an air stream entering a building. This would be a highly desirable scenario for the solar heat exchange panels of preferred embodiments as they can then be utilised gainfully all year 15 round - providing direct heat energy to a building in winter and providing cooling energy in summer. The simple low cost design of the present embodiment allows the heat energy to be efficiently harvested and transferred to a refrigeration unit, thus making such a system feasible, Where insufficient solar heat energy is available from the solar panels to-provide all of the cooling energy required then 20 the solar panels could be used to provide supplementary or pre-heating of a fluid stream which is then brought to the desired temperature by conventional means (typically a boiler). In this way the energy required from conventional means (e.g. gas) is minimised by the use of solar radiation harvested in the preferred panels. The inventor has recognised that according to the Australian Institute of 25 Refrigeration Air Conditioning and Heating website (www.airah.org.au) we learn that solar energy flow that warms the earth's atmosphere during the day needs to be kept in balance, and in simplistic terms, the earth does this by reradiating part of the energy received from the sun back to the sky at night. In this way a balance can be achieved between the solar warming from the sun and solar 30 cooling from the night sky. Space above the earth's surface is generally very cold and effectively acts as a radiant black body drawing radiant energy from warmer objects such as the earth. The effective temperature of the night sky comprising the atmosphere near the earth's surface is typically around 10 to 15 degrees WO 2010/025507 PCT/AU2009/001146 25 cooler than the air temperature at the earth's surface, giving an effective temperature at times as low as -15'C, The effective sky temperature encountered on any given night is dependant on a number of factors including air temperature, cloud cover and the moisture content of the air. When the sky is 5 cloudy or when there is a relatively large amount of water vapour in the air, the effective sky temperature will be warmer. However particularly on clear, dry nights the effective sky temperature can be very low, drawing very large amounts of heat from the earth through this radiant exchange. An example of this night solar cooling effect in action is provided in Figure 15. This graph shows actual 10 measurements of roof temperature variations, recorded by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). Measurements were taken on the metal deck roof of a CSIRO building in Highett, Victoria, Australia, during a typical Melbourne summer week. The roof temperature data clearly shows that the roof heats up during the day to around 50'C. Then at night the 15. roof cools to levels typically in excess of 10'C below ambient, even following very hot days. This clearly shows the effect of radiant heat exchange to the solar night sky occurring in Melbourne. Accordingly, another feature of the solar heating and radiant cooling of preferred embodiments is the ability of the multi-walled panel to radiate energy to 20 send heat into the night sky. The multi-walled panel takes advantage of the solar cooling effect of the night sky to produce cooled air for buildings during nights of -elevated temperature, for example hot summer nights. Most houses will heat up on a summer day and will tend to be warmer than 25 ambient at night. As the effective temperature of the multi-walled panels, which in preferred forms will be situated on the roof of a building, are typically up to 10 degrees C cooler than the ambient temperature, the system can effectively cool the house down during hot summer nights. 30 In addition to introducing cool air to the house the act of circulating fresh air through the house can help to make the house feel cooler by increasing evaporation off a person's skin. This is often achieved by using ceiling fans which WO 2010/025507 PCT/AU2009/001146 26 are effective at circulating the internal air. The present embodiment's system will circulate air that is significantly cooler than the inside air, as well as being fresh air. Thus present embodiments can be used to significantly reduce the air 5 conditioning load for a building during a hot day. For example, a typical office building is air conditioned during the day and unoccupied at night so the a/c is often turned off overnight. In such a situation in a preferred embodiment, panels of the present invention may be utilised and could run all night to reduce the core temperature of the building. Then the next day the lower temperature of the bulk 10 of the thermal mass of the building would result in a reduced requirement for air conditioning. This would be even more significant after a weekend where a typical office building is not air conditioned and thus heats up significantly on summer days. The-cooling process of the present embodiment in a preferred form, where 15 fresh air is pulled into the solar air panel and cooled down with the radiant night sky, may be described as follows: 1. Detect the temperature output of the air cooler, 2. The temperature information is conveyed to a temperature controller 3. The controller turns the fan(s) on or off at a preset temperature(s). If the 20 preset temperature (for example, temperature inside the building) is above that of the cooler output the system will provide cooling (such as during clear nights). 4. When the output temperature from the cooler is greater than the preset temperature, the controller will shut of the fan(s). 25 The present embodiment may, under certain conditions, reach high temperatures if no air is circulating through the system. Temperatures above 120 degrees C are undesirable for extended periods of time due to the impact on any plastic materials that may be used. In this situation a thermal relief valve may be fitted to the system to allow air to freely circulate through the heat exchanger to 30 the outside atmosphere in the circumstances that the heat energy is not desired inside the building or not able to be circulated into the building (eg a fan failure). In the ideal scenario this relief valve will be fully automatic. A relief valve may comprise any heat activated mechanism; examples include a wax actuator or wax WO 2010/025507 PCT/AU2009/001146 27 motor, or a bi-metallic strip. The heat activated mechanism would be used to open a vent in the system under high temperature conditions. This vent would allow the warm air to escape due to the natural convection principles of warm air rising, at the same time drawing cooler air into the base of the solar panel and 5 thus lowering the temperature of the system. When the temperature dropped to a pre-defined level (as determined by the design of the heat activated mechanism) the vent would close. Other Applications: Applications for embodiments of the present invention that could be 10 implemented by means within the understanding of persons skilled in the art are mentioned here as follows. Wood Drying The preferred system can be used to provide heat, or supplementary heat to the process of drying timber. Typically a large amount of energy is used to 15 drying timber on an industrial scale. The preferred system could dramatically reduce the energy required to dry timber. Fruit Drying The preferred system can be used to provide some or all of the heat to dry fruit such as grapes (sultanas), apricots, apples, pears and tomatoes 20 Low Humidity Environments The preferred system can be used to provide warm fresh and filtered air to any environment where low humidity and/or warm and/or fresh air Is Important. Some examples include: Buildings where painting is being carried out to accelerate paint drying 25 whilst providing a flow of fresh air to reduce build up of paint fumes. This may include automotive painting, industrial painting of any products or even artistic painting of surfaces or canvas. Buildings or warehouses where products are being stored that may be susceptible to mold or humidity. For example clothes, food, furniture, any fabrics 30 are often stored in warehouses. The preferred system could provide sufficient warm air to reduce or eliminate the need for supplementary heating whilst ensuring the products are not damaged by mould or moisture.

WO 2010/025507 PCT/AU2009/001146 28 Buildings where processes that generate fumes or high humidity are carried out. For example cooking, painting, laboratories, automotive repair garages Supplementary heating for greenhouses where food or plants are grown 5 Libraries or buildings where books, archives or any kinds of documents are stored Buildings or warehouses where goods that are subject to corrosion are stored, for example.electronics goods that are in storage, or metal products. Integration with Solar PV: 10 The preferred system can be integrated with solar Photovoltaic (PV) panels. Solar PV usually runs most efficiently below 25 degrees, it is not uncommon for solar PV to exceed over 60 degrees. By simply integrating the PV together with the preferred system, the panel could potentially harvest the waste heat away from the PV to provide heating for the home, whilst increasing the 15 efficiency of the Solar PV. Heating Water: The preferred system described in embodiments above is used primarily 20 for heating an air stream. The same technology may also be used for heating a liquid stream, or more specifically a water stream. There are many applications where a body of water is required to be heated. These applications include heating water for a swimming pool, pre heating water for industrial or commercial applications (for example water might 25 be pre-heated prior to entering a boiler where it might be further heated to produce steam - eg in a power station or building heating system) or heating water for baths/showers. Presently water is heated either using existing solar water heaters or using a powered heating system such as a gas fired heater or electric heating 30 elements. Powered heating systems have the disadvantage of consuming precious natural resources such as gas or coal to generate electricity, which in turn produces pollution including greenhouse gases. They are also expensive to run on an ongoing basis.

WO 2010/025507 PCT/AU2009/001146 29 Existing solar water heaters in the form of flat plate heaters or evacuated tube collectors can be very effective in heating relatively small volumes of water for use in domestic situations (baths/showers). A typical house with a solar hot water system will heat a 200 - 300litre tank. These flat plate or evacuated tube 5 collectors are however quite costly so would not be suitable for heating a large volume of water such as a swimming pool because the capital cost of the equipment would be very high. A typical spa holds 2,000 to 4,000 litres and a swimming pool typically holds between 20,000 and 100,000 litres so the volume is many times that of a domestic hot water system. 10 In order to provide heating for swimming pools at a cost effective rate the industry has developed much lower cost heaters for heating swimming pool water in large volumes, These heaters are typically an array of black plastic or rubber tubes/pipes that are laid out flat on a surface such as the roof of a house or garage adjacent to a pool. Whilst these systems are low cost they have the 15 disadvantage of being low efficiency and can compromise the aesthetics of a house. The preferred system of the present invention can be used to heat relatively large volumes of water with significantly higher efficiency than conventional black tubes. The reason for the higher efficiency is that the black 20 (hot) surface is insulated from the atmosphere by the plastic polycarbonate extrusion. Therefore the heat losses to atmosphere are far less, so the net heat transferred to the water is greater for a given surface area. In addition to improved efficiency the preferred system is far more aesthetically pleasing. The smooth profile of the panels can neatly and cleanly fit 25 into the roof profile of a house or building in a far less obvious manner than conventional solar pool heating systems which comprise of an array of pipes and manifolds. The preferred panels can also be used as the roofing material on a building including a house, garage or roof of a pool house or patio. Performance data 30 Product performance is a function of the size of the unit, the solar radiation conditions and the angle of the sun.

WO 2010/025507 PCT/AU2009/001146 30 Prototype testing has shown that the solar heater is capable of harvesting between 400 and 700 watts per square meter of solar collector area on a sunny but cold winter day. The graph of figure 15 shows the temperature of the air entering the house 5 on a mostly cloud free winter sunny day in June 2008. The system used in this test was 6M in area and ducted to 6 outlets in a 200m 2 house. The graph of figure 16 depicts information from the same system on a cool day in June 2008 with intermittent (but very dense) cloud cover. As can be seen, the air temperature varies. One observation Is that the system responds very 10 quickly to sunshine. Even on days where the sun is largely hidden behind clouds this heating system can extract useful heat energy and transfer it into the house. A second set of performance data, shown below, shows both the output temperature from the solar collector but also the impact of this heating on the 15 actual air temperature of a house. Graph One (shown in figure 17) shows the temperature of the air entering the house on a cold but sunny day in July 2008. The system used in this test was only 3 m2 in area and the air outlet temperature peaked at around 27 deg C. 20 Graph Two of figure 18 shows the impact that this same system had on the temperature of the house on the same day. Temperatures were recorded in two identical south-facing bedrooms. One bedroom was heated witi the preferred air heater, the other was not heated at all. There was no supplementary heating in the house. As can be observed the Preferred system increased the temperature 25 of the heated room by 5 degrees C. Graph Three of figure 19 shows the temperature of the air entering the house on a very cloudy day in July 2008. Even in conditions of complete cloud cover the preferred embodiment's technology is capable of harvesting a significant amount of heat energy and transferring this into the house. 30 Graph Four of figure 20 shows the impact that this same system had on the temperature of the house on the same (cloudy) day. Temperatures were recorded in two identical south-facing bedrooms. One bedroom was heated with the preferred embodiment's air heater, the other was not heated at all. There was WO 2010/025507 PCT/AU2009/001146 31 no supplementary heating in the house. As can be observed the Preferred system increased the temperature of the heated room by 2-3 degrees C. While the invention has been described in connection with preferred embodiments and examples, it will be understood by those skilled in the art that 5 other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention, Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification is considered as exemplary only, with the true scope and spirit of 10 the invention being indicated by the following claims. "Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof."

Claims (26)

1. A method of heating a fluid utilising solar energy, the method comprising the steps of: 5 absorbing solar radiation into a first structural portion; absorbing radiation that is re-emitted from the first structural portion into a second structural portion located proximate the first structural portion; guiding a fluid flow between the first and second structural portions. 10

2. A method as claimed in claim 1 wherein the step of guiding further comprises exchanging heat between the fluid and the first and/or second structures by means of convection.

3. A method as claimed in claim 1 or 2 wherein the first structural portion 15 comprises a low thermal mass absorbent medium.

4. A method as claimed in any one of claims 1 to 3 further comprising the step of: insulating the exchange of heat between the fluid and the first and/or 20 second structural portions by locating a third structural portion peripherally with respect to the first and second structural portions.

5. A method as claimed in claim 1, 2, 3 or 4 wherein the fluid comprises one or a combination of: 25 air; a natural gas; a natural gas mixture; a synthetic gas; a synthetic gas mixture 30 water.

6. A method as claimed in any one of claims 1 to 5 further comprising the step of WO 2010/025507 PCT/AU2009/001146 33 circulating the fluid which has flowed between the first and second structural portions to at least one of: a domestic environment; a commercial environment; 5 an environment occupied by humans and/or animals an environment occupied by plants and/or equipments.

7. Apparatus for heating a fluid utilising solar energy, the apparatus comprising: 10 a first structural portion comprising a medium adapted for absorbing solar radiation and re-radiating energy substantially immediately; a second structural portion located proximate the first structural portion which is adapted for absorbing re-radiated energy from the first structural portion; wherein the first and second structural portions form a fluid flow path for 15 fluid to exchange heat energy between the fluid and the first and/or second structural portions.

8. Apparatus as claimed in claim 7 further comprising a third structural portion located peripherally about the first and second structural portions and 20 adapted to insulate the exchange of heat energy between the fluid and the first and/or second structural portions.

9. Apparatus as claimed in claim 8 wherein the second and third structural portions are adapted to be at least partially transparent to solar radiation, 25

10. Apparatus as claimed in any one of claims 8 or 9 wherein at least the second and third structural portions form an integral structure and are comprised of the same material. 30

11. Apparatus as claimed in claim 10 wherein the first structural portion forms a central core of the integral structure. WO 2010/025507 PCT/AU2009/001146 34

12. Apparatus as claimed in any one of claims 7 toll further comprising circulation means for circulating the fluid to at least one of: a domestic environment; a commercial environment; 5 an environment occupied by humans and/or animals.

13. Apparatus as claimed in any one of claims 7 to 13 wherein the fluid comprises one or a combination of: air; 10 a natural gas; a natural gas mixture; a synthetic gas; a synthetic gas mixture water. 15

14. A fluid heat exchange system for use in providing temperature control of an enclosed environment comprising: at least one multi walled panel adapted for communicating radiant energy between the exterior and a core of the panel and configured in cross section to 20 provide at least one channel allowing movement of fluid through the panel, a centrally disposed high radiant energy absorbent portion adapted to re-radiate upon being heated wherein the moving fluid exchanges heat with the centrally disposed high absorbance portion. 25 .

15. A system as claimed in claim 14 wherein the multi walled panel comprises a polymeric material that is highly transmissive of radiant energy and also thermally insulating.

16. A system as claimed in claim 14 or 15 wherein the absorbent portion 30 comprises one or a combination of: thin metallic strips disposed along the length of the panel; thin metallic strips coated with solar energy absorbent paint disposed along the length of the panel; WO 2010/025507 PCT/AU2009/001146 35 internal cavities of the panel with metallic coating; thin plastic opaque strips disposed along the length of the panel internal cavities of the panel with an opaque plastic coating or surface. 5

17. A system as claimed in any one of claims 14 to 16 wherein the multi walled panel further comprises at least one insulating layer adapted to confine radiant energy to the fluid flow channels such that heat exchange is optimized between the fluid and the absorbent portion. 10

18. A system as claimed in any one of claims 14 to 17 adapted to provide one of: heating of the enclosed environment by, primarily during daylight, transferring heat from solar radiation external of the panel to the fluid flowing through the multi walled panel, and; 15 cooling of the enclosed environment by, primarily at night, transferring heat from fluid flowing -through the multi walled panel to the absorbent portion to subsequently be radiated externally of the panel.

19. A system as claimed in any one of claims 14 to 18 further comprising one 20 or a combination of: a manifold for collecting outlet air from the multi walled panel; a ducting system for distributing the outlet air to the enclosed environment; a controllable fan system for switching' control of the air flow into the enclosed environment. 25

20. A system as claimed in any one of claims 14 to 19, wherein the multi walled panel is adapted to connect to at least one other multi walled panel to provide a heat exchange system that is modular and scalable. 30

21. A system as claimed in any one of claims 14 to 20, wherein the multi walled panel is adapted to conform to the form of building it is installed upon. WO 2010/025507 PCT/AU2009/001146 36

22. A system as claimed in any one of claims 14 to 21, wherein the multi walled panel.is adapted to form a portion of a building.

23. A method of exchanging heat for use in providing temperature control of 5 an enclosed environment, the method comprising the steps of: communicating radiant energy between the exterior and a core of a multi walled panel; channelling fluid through the multi walled panel; exchanging heat between the fluid and a centrally disposed high radiant 10 energy absorbent portion of the core of the multi walled panel, wherein the absorbent portion is adapted to re-radiate energy upon being heated by one of the fluid or radiant energy communicated from the exterior of the panel.

24. A method of fabricating a heat exchanger, the method comprising the step 15 of extruding a multi walled structure to form: a centrally disposed high radiant energy absorbent portion adapted to re radiate upon being heated, and; cavities adjacent the centrally disposed portion adapted for allowing a fluid to pass there through and exchange heat energy between the fluid and the walls 20 of the cavities.

25. A method or protocol as herein described.

26. Apparatus, device or system as herein described. 25