SOLAR THERMAL CELL

Abstract: A solar radiation energy collector must include such a means of stopping solar radiation that no radiation is reemitted. Known art black, heat-binding absorbing surfaces are of this kind. The collecting of solar radiation energy should take place using a liquid jacket covering the entire south-facing pane of the roof, the said liquid jacket being implemented by means of a relatively inexpensive, well-sealed structure that should also be capable of withstanding strains such as that caused by snow. Underneath solar radiation energy collector's intermediate spaces (5) for the heat-collecting liquid, there is a dark-surfaced mineral wool board (1) stopping solar radiation. The intermediate space (5) may be located between two light-admitting membranes (2 and 3) and overlying the membranes (2 and 3) there may be a light-admitting sheet of corrugated fibreglass (4). Between the membranes (2 and 3) or equivalent there may be ridges (6) forming cross-sectionally rectangular intermediate spaces (5) between the membranes (2 and 3). The intermediate spaces (5) may be arranged in tiers; e.g. three tiers with the uppermost tier being a heat-insulating air space and the lowermost tier containing a mineral wool board (1).

Description: SOLAR THERMAL CELL. The invention relates to a solar energy collector. The amount of energy received by the solar energy collector is nearly doubled as the solar radiation is not reflected back from the collec¬ tor and as the radiation energy is transmitted directly to a liquid jacket the size of the entire surface of the collector. In experiments executed with the obstacle to solar radiation consis¬ ting of a dark mineral wool board, the temperature in the thin liquid jacket located between membranes on top of the mineral wool board unexpectedly rose to a level approx. 25°C higher than in the liquid piping of a known art metal-surfaced energy collector. Also unexpectedly, the experiments resulted in the formation of a thin, even jacket of water equal in width to the entire surface and caused by the weight of roof material made of corrugated fibreglass sheets and the liquid's surface pressure and capillary force. Temperature measurement tests also revealed that the as such rela¬ tively high amount of recoverable energy could be further increased by having a air gap between the liquid surface and the membrane over¬ lying it. A solar energy collector the size of the entire pane of the roof, for example, should function advantageously also as a roof and it should be readily and securely mountable through a mineral wool board onto the underlying roof structural timber or over an existing roof (e.g. with nails) so that neither the liquid jacket's liquid nor rain water seep through fastening points or seams. When placed on top of a greenhouse, for instance, a solar energy col¬ lector should provide protection against excessive insolation and UV radiation and in winter it should act as an insulation layer over the greenhouse. Patent publication DE 2724035 presents a tiered solar radiation collector in which the heat energy is transferred to a metal piping underlying a black metal sheet while overlying the collector there are light admitting plastic membranes and a sheet of glass. Under¬ neath the collector there is known art heat insulation. Patent publication FI 63117 describes a lens solar cell whose surface consists of liquid lenses placed side-by-side and thus forming a heat-collecting liquid jacket. The solar energy collector described in patent publication DE 3541713 consists of a heat-collecting sheath formed over a black-surfaced aluminium sheet by gluing a glass plate over it. A horizontal cavity level is thus formed between the aluminium and glass for a fluid sub¬ stance, heat insulation is provided at the rear of the underlying sheet. In the solar collector-accumulator in accordance with patent publica¬ tion DE 4103344 there are two plastic water bags one on top of the other. Between these bags there is a heat exchanger; e.g consisting of flat metal pipes. The bag on top admits light while the bag below it is black or its lower surface is black. When filled with water, the bags are approximately 2 - 5 cm in thickness. Underneath the bags there is known art heat insulation. The roof covering making use of energy in accordance with patent pub¬ lication DE 3529970 is provided with intermediate spaces for liquid to flow in. The structure is sealed and it withstands wear such as walking of top of it. It is formed of a metal membrane or a multiple membrane. A surface membrane is placed over the roof covering. The solar energy collector in accordance with DE patent publication 3537223 has a frame made of material such as polystyrene or metal with an overlying absorption membrane of material such as black copper or aluminium membrane and a specially constructed tetrafluor- ethylene plastic membrane placed over the collector. The membrane can be welded to seal it and overlying there may be a grid formed of brass pipes to prevent the wind from hindering the functioning of the membrane. The polystyrene frame may form the underlying heat insula¬ tion. Uppermost in the roof solar collector in accordance with patent pub¬ lication NO 170698 is a light-admitting sheet of polycarbonate. Underneath the overlying sheet there is a sheet of aluminium painted black to act as the absorbing sheet, the said aluminium sheet being known to absorb and bind to itself radiation energy of the sun. Via its under surface and the mediation of a heat exchanger sheet, the absorbing sheet is in contact with a mediating piece, whose upper surface is provided with channels for the down-flowing liquid. The mediating piece located underneath the heat exchanger sheet can be of a heat-insulating type. The aforementioned solar radiation energy absorbing and binding metal-surfaced solar collectors and liquid-jacketed lens solar cells and liquid-jacket solar collectors and liquid-jacket accumulators and covers reflect back a relatively large proportion of the solar radia¬ tion and they are structurally relatively complex and expensive. Approximately 65% of the solar radiation energy was reflected back and transferred from known art metal-surfaced solar energy collec¬ tors. The price per square metre of metal-surfaced collectors is relatively high and the service life of the metal in the collector's variable conditions is relatively short when compared to boards of mineral wool, for instance. A porous, black mineral wool board does not bind to itself nor conduct solar radiation energy as do metal and plastic absorbers, but solar radiation is not reflected back from the black, porous wool. A mineral wool board type for flat roof construc¬ tion and capable of withstanding the weight of snow is known. All solar energy collectors require heat insulation underneath them and a light-admitting insulation layer above. The solar energy collector in accordance with patent application FI 922793 has a light-admitting cover and a liquid jacket above a dark surface and a heat insulation layer underneath, and underneath the liquid jacket there is a layer stopping solar radiation in the form of a dark-surfaced board of mineral wool or equivalent, and the liquid jacket can be formed between membranes. The liquid-jacket solar cell roof in accordance with FI utility patent NRO 350 embodies a liquid jacket between membranes and roof material consisting of corrugated fibreglass sheets or equivalent, and between the membranes there are ridges forming intermediate spaces for the liquid. The liquid-jacket solar cell roof in accordance with FI utilit patent NRO 678 has at least two tiers of intermediate spaces betwee membranes and the liquid jacket is located in the lower intermediat space tier overlying the mineral wool board and the uppermost tie containing air forms a surface heat insulation roof cover. Known art solar membranes, such as solar membranes made of polyeste plastic, modify the wave length of solar radiation and thereby pre vent the radiation from returning through the membrane. The polyeste solar membrane is made of polyethylene-terephtalate membrane. A cor responding membrane is made of teflon FEP membrane. Known are tetra fluorethylene plastic solar membranes and polycarbonate solar mem branes, and triple-layered sheets made of polycarbonate plastic b means of extrusion technique in which sheets there are rectangular intermediate spaces in several layers. The clear polycarbonat plastic is capable of withstanding the heat of the solar radiatio collector and of the weight of the snow on the roof. Dark liquids such as water in which soot particles and black colour prevent th passing through of solar radiation are known. The purpose of the invention is to bring about a collector of sola radiation energy in which the solar radiation energy is collecte either into a liquid jacket covering the entire surface and relati¬ vely little of the solar radiation is reflected back, and the collec tor is advantageously the size of the entire pane of a roof and form ing a roof capable of withstanding the weight of the snow. These pur poses can be realised in accordance with the characteristics of th invention as defined in the patent claim. In the following, the invention is described in more detail by refer ring to the accompanying drawings, which illustrate applications o a solar energy collector in accordance with the invention: FIG. 1 and FIG. 2 show a solar radiation energy collector with a overlying sheet of corrugated fibreglass. FIG. 3 shows a collector with several tiers of intermediate spaces. The solar radiation energy collector has a light-admitting cover an a jacket of liquid overlying a dark surface and a heat insulatio layer underneath. Underneath the intermediate space (5) containin the liquid there is a layer stopping solar radiation consisting of dark-surfaced mineral wool board (1) or equivalent. The intermediate space (5) containing the liquid may be located bet ween two light-admitting membranes (2 and 3) or an equivalent such a a board. The membranes (2 and 3) may, for instance, consist of 0.4 m polycarbonate. Overlying the membranes (2 and 3) and compacting ther may be a cover of corrugated fibre glass (4) or equivalent. Betwee the membranes (2 and 3) or their equivalent there may be ridges (6 or equivalent, these forming intermediate spaces (5) between the mem branes (2 and 3), such as those rectangular in cross section, such a the membranes (2 and 3) and the ridges (6) are of the one and th same material. The intermediate spaces (5) may be arranged in two o more tiers and the tier overlying the mineral wool board (1) ma contain a liquid and uppermost there may be air forming the surfac heat insulation cover. The lowermost intermediate space (5) may, fo instance, be 5 cm in height and it may contain a mineral wool boar 81). The liquid may be coloured black such as dark water. The edges of th panels of cells may have known art well sealed tongue grooves en¬ abling fixing to form a roof. Example 1: FIG. 2. The mineral wool board (1) was a stiff flat roof sheet 50 mm in thickness, whose surface had been painted black using black spray paint. Overlying the mineral wool board (1) was a cell panel 6 mm in thickness provided with ridges (6) and intermediate spaces (5) between the ridges, and it was made of one material, poly¬ carbonate, using extrusion technique and it was 2 m x 6 m in size. The surface membranes (2 and 3) of the cell panel and the ridges (6) were 0.4 mm in thickness. Overlying the cell panel was a light-admit¬ ting fibreglass cover with 70 mm corrugation. The solar radiation energy collector was formed as the covering over the pane of a roof by fastening it through the corrugated sheet and cell panel and mineral wool board (1) by means of fastening nails. Water was led in from above to all other intermediate spaces (5) except the one through which the fastening nail went. The heads of the nails were covered by fibreglass resin to seal their entry points. Example 2: FIG. 3. The polycarbonate cell panel contained inter¬ mediate spaces (5) in three tiers. The uppermost intermediate spaces (5) were air intermediate spaces forming a light-admitting surface cover. The energy-collecting liquid was made to pass through the middle tier while the lowermost, high tier contained a mineral wool board (1). The cell panels were provided with tongue grooves by which they were linked to one another so as to form the cover for the pane of a roof, for instance.

Claims: CLAIMS : 1. A solar radiation energy collector with a light-admitting cover and a liquid jacket overlying a dark surface and a heat insulation layer underneath, characterized in that the underneath the inter¬ mediate space for the liquid (5) there is a dark-surfaced mineral wool board (1) or equivalent stopping solar radiation. 2. A solar radiation energy collector as claimed in claim 1, charac¬ terized in that the intermediate space for the liquid (5) is located between two light-admitting membranes (2 and 3) or the equivalent, such as boards. 3. A solar radiation energy collector as claimed in claim 1 and/or 2, characterized in that overlying the membranes (2 and 3) there is a light-admitting corrugated fibreglass cover (4) or equivalent. 4. A solar radiation energy collector as claimed in claim 1 and/or 2 and/or 3, characterized in that between the membranes (2 and 3) or their equivalent there are intermediate ridges (6) or equivalent, which form intermediate spaces (5) for the liquid between the mem¬ branes (2 and 3), such as those rectangular in cross section, such as the membranes (2 and 3) and the ridges (6) are of the one and the same material. 5. A solar radiation energy collector as claimed in claim 1 and/or 2 and/or 3 and/or 4, characterized in that the intermediate spaces (5) are arranged in two or more tiers and the tier overlying the mineral wool board (1) contains a liquid while the uppermost tier contains air. 6. A solar radiation energy collector as claimed in claim 1 and/or 2 and/or 3 and/or 4 and/or 5, characterized in that the lowermost intermediate space (5) contains a mineral wool board (1) or equivalent. 7. A solar radiation energy collector as claimed in claim 1 and/or 2 and/or 3 and/or 4 and/or 5 and/or 6, characterized in that the liquid is coloured dark, such as dark water. 8. A solar radiation energy collector as claimed in any of the above claims, characterized in that the edges of the cell panels are provi¬ ded with known art tongue grooves for fastening to form a roof cover.

Inventors: REIALA MAUNO SAKARI, REIALA, MAUNO, SAKARI
Applicants: REIALA MAUNO SAKARI, REIALA, MAUNO, SAKARI
Application year: 1993
Main classification: F24J2
IPC codes: E04D13, F24J2