A SOLAR HEAT COLLECTING APPARATUS

Abstract: A solar heat collecting apparatus of the kind which comprises a plurality of parallel ducts, through which a heat transport agent circulates. The object of the invention is to provide a solar heat collecting apparatus which is composed of conventional components, which is not expensive to manufacture, which does not have any leakage problems and which has a very large heat collecting surface. These objects have been solved by the fact that the ducts (16) are made of a bottom corrugated plate (11), the upper surface of which is reflective, and an upper transparent plate (13) formed with the same corrugations, the wave troughs (14) of which are located to fit-up against the wave-crests (15) of the bottom plate. In the ducts (16) is accommodated a light- and heat-absorbing tube (18), which at least at both ends of the ducts at the transition between one duct to the adjacent duct is formed as a corrugated or screw-line shaped tube.

Description: A S OLA R H EAT COL L ECT I NG A P PARATU S The present invention relates to a solar heat collecting apparatus of the kind which comprises a plurality of parallel 05 ducts through which a heat transport agent circulates. Background of the invention Solar heat collecting apparatuses are available in many 10 different forms and the general similarity in most of them is that they must be specially manufactured for the intended purpose and for this reason their construction is complicated and they therefore command a relatively high price. 15 A big problem with plate-shaped solar heat collecting apparatuses, where the plate is divided into several parallel ducts , is the connection between the individual ducts at both ends of the plate so that a continuous duct is provided.. To reach this purpose, a number of different solutions have been 20 proposed in form of collecting ducts and the like, which in some way should be connected with each individual duct in the plate. Due to the large thermal movements which solar heat collecting apparatuses are subjected to, the transition between the parallel ducts is a big problem, as leakage very 25 often appears in these transitions. Another problem is that the heat-absobing surface of the solar heat collecting apparatus in many cases is unsufficient . 30 The object of the invention and its most important features The object of the invention is to provide a solar heat collecting apparatus which consists of conventional components, which can be purchased in well stocked building 35 material stores and the like. As standard components may be used, the price per square meter of heat collector can be kept very low at the same time as well-tried materials are to be used. Leakage problems are not to be feared, as an unbroken conveying duct will be usefci for the heating agent, by which the system will be very dependable. A further object is to provide a solar heat collecting apparatus with a very large heat collecting surface. These problems have been solved by the fact that the ducts are formed by a bottom corrugated plate, the upper surface of which is reflecting, and a second upper transparent plate formed with the same corrugations, the wave troughs of which are placed to fit-up against the wave crests of the bottom plate, and a light- and heat-absorbing tube is acco odated in the ducts, which "at least at both ends of the duct at the transition from one duct to the adjacent duct is designed as a corrugated or screw-line shaped tube. Description of the drawings Fig. 1 shows a part of a solar heat collecting apparatus according to the invention in a top view. Fig. 2 shows a section through a smaller part of the solar heat collecting apparatus according fig .1. Description of embodiments According to the invention the solar heat collecting apparatus is composed of a bottom corrugated plate 11 , such as steel sheet, the upper side of which facing away from the frame 12 has a bright metallized surface, so that it has a good re lectivity. On the top of this bottom plate 11 a transparent plate 13 with the same corrugations is placed, appropriately of a plastic material with a very high light transmission. The upper corrugated plate 13 with its wave troughs 14 is placed to fit the wave crests 15 of the bottom corrugated plate 11 , so that closed parallel ducts are formed. A sealing compound 22, for example of silicone, could possibly be fixed between the installation surfaces of the two plates. Both corrugated plates are fastened to their frame, for example a roof surface on a conventional way by means of screws 17 arranged in the wave trough 14 between two ducts 16 in the upper transparent plate 13. In the ducts 16 a loose tube is laid, preferably of an UV-resistant plastic material, for example polyethylene or polypropylen . The out side of the tube is black, and possibly coated with a specially favourable light- and heat-absorbing layer. At least those parts of the tube which bridge the distance between two adjacent ducts 16 at both ends of the plates are designed as corrugated tubes, but with advantage the whole tube can be corrugated. In order to attain as good heat transmission as possible with as small volume of transport agent as possible, an inner tube 19 with a smaller transverse cross section is arranged in the corrugated tube 18. The agent is intended to circulate in the space 20 between the inner tube 19 and the corrugated tube 18. Possibly the space 20 between the two tubes at one end of the solar heat collecting apparatus could be connected to the inside of the tubes so the water which has already been warmed can one more time pass through the winding pipe. Instead of a corrugated pipe or tube a helical pipe could be used, which with relatively tight windings could be placed in the ducts 16 in the same way as the corrugated tube. By making the heat transmission tube 18 corrugated or helical, the tube can be bent 180 without reducing the effective cross section. The corrugation also results in that the heat agent during the transport continuously is mixed by means of the arising turbulence caused by the corrugatoin, which at the same time gives a very high heat-absorption area. Further advantages obtained by corrugated tubes are that it can take up the thermal length alterations, so that the tube is always tensionless, even with great temperature variations and as the tube can be put into the duct 16 in an unbroken length, the risk for leakage at the transitions betwen one duct to an adjacent duct is practically eliminated. If the solar heat collecting apparatus is utilized on a roof, connection pieces for the upper and bottom parts of the plates offered for sale on the market could be used to cover the passages between the ducts. This kind of connection pieces are available in roof termination design as well as in ridge design. If by any reason some mistake would arise in a solar heat collecting apparatus manufactured in this way the damaged part can easily be replaced, as all the parts are easily accessible when the connection plates are removed. In order to avoid that an air circulation arises in the ducts 16 there is arranged in both ends of each indevidual duct a sealing member 21, which can consist of a pre-fabricated foamed plastic plug or the like, or the plug could also be provided on the place by foaming of a plastic material. The invention is not limited to this shown embodiment, but a number of alternative embodiments are possible within the scope of the claims.

Claims: CLAIMS 1. A solar heat collecting apparatus of the kind comprising a plurality of parallel ducts through which a heat transport agent is intended to circulate, c h a r a c t e r i z e d i n. that the ducts (16) are made of a first bottom corrugated plate (11) , the upper surface of which is reflecting, and a second upper transparent plate (13) formed with the same corrugations, the wave troughs (14) of which are placed to fit-up against the wave crests (15) of the bottom plate, and that in the ducts (16) is placed a light- and heat-absorbing tube (18) , which at least at both ends of the ducts at the transition between one duct to the adjacent duct is designed as a corrugated or screw-line formed tube. 2. A solar heat collecting apparatus according to claim 1 , c h a r a c t e r i z e d i n, that the tube (18) along its whole length is corrugated, and inside said tube an inner tube (19) with a small cross section is arranged, and that the heat transport agent is intended to flow in the space (20) between the two tubes. 3. A solar heat collecting apparatus according to claim 1 or 2 , c h a r a c t e r i z e d i n, that every iπdevidual duct (16) in both ends around the tube (18) is closed by means of a sealing member (21 ) , for example a foam plastic plug or other. -BϋKtA fY.PI Λ •

Inventors: WERNBORG RUNE, WERNBORG, RUNE
Applicants: MEDIPLAST AB
Application year: 1983
Main classification: F24J3
IPC codes: F24J2