DE102007020230A1 - Collector for converting solar energy into heat comprises a container with a heat-transfer medium consisting of a liquid with a high heat absorption capacity and a boundary made of a material transparent to solar radiation - Google Patents

Abstract

Solar collector (10) comprises at least one container (12) creating a cavity (14) that has a boundary (16) facing the solar source made of a material transparent to solar radiation. The cavity contains a heat-transfer medium consisting of a liquid possessing a high heat absorption capacity or a liquid with particles possessing a high heat absorption capacity. Preferred Features: The container is made of plastic and/or glass. The boundary comprises a heat-reflecting coating consisting of photovoltaic elements. The heat-transfer medium is a black liquid.

Description

The The invention relates to a solar collector with at least one, at least a cavity forming receptacle for a heat transfer medium, wherein the at least one Holding container via a flow and a Return with a heat sink in a closed Circuit is connectable.

Solar collectors of the generic type are known. These convert radiant energy of the sun into heat and transfer it to a heat transfer medium. This is done according to the prior art in two steps. First, a material provided with a radiation-selective coating, usually a metal, converts the infrared region of the incoming radiation into heat. This heat is then either transferred directly to the heat transfer medium or is first delivered to a pipe system or the like, in which the heat transfer medium is circulated and thereby heated. A disadvantage of these known solutions is especially the high, specific material requirements and high specific gravity. Such known solar collectors are for example in DE 31 34 865 A1 . DE 27 00 714 A1 . DE 35 372 23 A1 . DE 26 46 174 A1 . US 4,790,293 and DE 90 27 94 described.

Of the Invention is based on the object, a solar collector of the generic To create a style characterized by a simple structure, has a high efficiency and is flexible.

According to the invention This object is achieved by a solar collector with the features mentioned in claim 1 solved. In that at least that of a heat source facing boundary of the at least one cavity of a for the solar radiation transparent material exists and the heat transfer medium has a high heat absorption capacity possessing liquid or a high heat absorption capacity owning, particle-containing liquid is it advantageously possible, the radiant energy of the heat source, usually the sun, directly absorbed by the heat transfer medium allow. A previous heat absorption by a the heat transfer medium surrounding pipe system or radiating surfaces connected to the conduit system and subsequent heat conduction into the heat transfer medium is thus avoided. Through this, almost direct warming of the Heat transfer medium can be a very much simpler, easier and more flexible construction of the solar collector achieve. By appropriate selection of the high absorption capacity owning liquid or contained in this Leaves particles with high heat absorption capacity optimally adapted to the actual circumstances Create solar collector.

The transparent material for heat radiation the heat source facing the boundary of at least one Cavity is preferably a plastic and / or a glass or like. This makes it possible, in particular, in addition to a weight reduction for the solar collector according to the invention important property of transparent for solar radiation Achieve material.

In Another preferred embodiment of the invention is provided, that the heat source facing away from the limitation of at least a cavity of the receptacle for a the heat radiation reflective coating comprises. This advantageously ensures that the heat transfer medium penetrating heat radiation emitted by the heat transfer medium not yet absorbed by the reflective coating is reflected back into the heat transfer medium and then can be absorbed. This allows the Efficiency of the solar collector according to the invention continue to increase.

The Reflective coating may in another preferred embodiment the invention inside or outside of the heat transfer medium receiving Cavity are arranged. In addition, in preferred Embodiment of the invention provided that the coating in the boundary of the cavity is integrated. Depending on the selected Embodiment, the reflective can be Coating in a simple way to the limitation by suitable Apply methods, such as vapor deposition or the like or very protected, when integrated into the boundary, Arrange. The reflective coating allows additional during operation of the solar collector without heat transfer medium, this is drained or in a separate reservoir recirculated, a mode of operation of the solar collector in which no heat is generated, but the incident heat radiation is largely reflected. This results a good insulation effect, for example, with the inventive Solar collectors equipped buildings or the like.

to Reduction of residues of the heat transfer medium in the cavity when draining the heat transfer medium may be the inner boundary of the cavity with a wetting reducing surface be provided.

Moreover, in a preferred embodiment of the invention, it is provided that the reflective coating comprises photovoltaic elements. This is advantageously possible, not in the Absorption solar collector located to convert the radiation energy of the sun in a conventional manner by means of photovoltaic elements into electrical energy. Overall, this results in a very flexible solar collector, which can be used in addition to the generation of heat energy, for example for heating purposes or for domestic water heating, in addition to the insulation properties for generating electrical energy.

Further preferred embodiments of the inventions will become apparent from the others, in the subclaims mentioned features.

The Invention will be hereinafter in an embodiment explained in more detail with reference to the accompanying drawings. Show it:

1 a schematic plan view of a solar collector according to the invention;

2 a schematic sectional view through the solar collector in the absorption mode and

3 a schematic sectional view through the solar collector in the reflection mode.

1 schematically shows a plan view of a total with 10 designated solar collector. The solar collector 10 includes a receptacle 12 for receiving an in 1 not shown heat transfer medium. The receptacle 12 forms at least one cavity 14 between an upper limit visible in the plane of the paper 16 and one not visible in the paper plane, under the boundary 16 arranged boundary 18 out. Within this at least one cavity, the heat transfer medium circulates according to the arrows shown 20 from a forerun 22 to a return 24 , The lead 22 and the return 24 are connected to a heat sink, not shown, for example, a heat exchanger for domestic hot water and / or Heizwassererwärmung. In addition, a delivery device (not shown), for example a pump, can also be arranged in the resulting circuit.

According to the in 1 shown top view is the solar collector 10 formed substantially rectangular. The size and shape of the solar collector 10 however, may vary and be adapted to the actual installation conditions. Thus, of course, other shapes, such as trapezoidal and / or the like are conceivable. To increase the stability can be provided that between the boundary 16 and the limit 18 individual webs are arranged, which ultimately lead to the formation of a plurality of adjacent, that is, parallel cavities through which the heat transfer medium 26 circulated.

2 shows a sectional view through the solar collector 10 , Same parts as in 1 are provided with the same reference numerals and not explained again.

In the sectional view, the formation of the at least one cavity 14 between the boundary 16 and the limit 18 of the receptacle 12 clear. The cavity 14 is in fluid communication with the flow 22 and the return 24 , Inside the cavity 14 is the heat transfer medium 26 , The heat transfer medium 26 is a liquid that has a high heat absorption capacity. The liquid can also be schematically indicated particles 28 comprising high heat absorption capacity. In the simplest case, there is the heat transfer medium 26 made of black dyed water. The material of the receptacle 12 consists for example of an optically transparent plastic or a glass. The transparency relates in particular to a radiation emanating from a heat source, for example the sun.

The side facing away from the heat source, that is the boundary 18 , is with a heat radiation reflecting coating 30 Mistake. The coating 30 is in the in 2 shown embodiment of the outside of the boundary 18 applied, for example vapor-deposited or the like. According to further, not shown embodiments, the coating 30 also on the inside, that is inside the cavity 14 on the limit 18 be upset. In addition, the coating is conceivable 30 into the limit 18 to integrate.

The in 1 and 2 illustrated solar collector 10 shows the following functions:
During the intended use of the solar collector 10 Solar radiation a, which emanates from the natural heat radiation (of the sun), acts on the solar collector 10 one. In this case, the solar radiation a penetrates the boundary facing the heat source, since this is essentially transparent to the solar radiation a. The solar radiation a strikes the heat transfer medium 26 which has a high heat absorbing ability. The thermal radiation is thereby converted into heat, that is, the heat transfer medium 26 heats up by a certain amount of temperature ΔT. By the in 1 clarified circulation of the heat transfer medium 26 The amount of heat absorbed by the heat transfer medium 26 to the heat sink, such as a heat exchanger transported. By the arrangement found it is achieved that the solar radiation a directly on the heat transfer medium 26 acts. Initially, there is no heating of the material of the solar collector 10 itself instead, from which then the heat should be transferred to the heat transfer medium by means of heat conduction, but this is heated directly. Eventually through the heat transfer medium 26 passing thermal radiation b, that is, this is not directly within the heat transfer medium 26 is absorbed by the reflective coating 30 in the heat transfer medium 26 reflected back and then contributes to a further heating of the heat transfer medium 26 at. The thermal radiation emanating from the heat source (the sun) can thus be effectively absorbed by the solar collector according to the invention with high efficiency and can be made available as useful heat of a heat sink. 2 thus represents the absorption mode of the solar collector 10 represents.

In 3 is the solar collector 10 in its so-called reflection mode. Identical parts are again denoted by the same reference numerals and not explained again.

The reflection mode is characterized by being inside the cavity 14 the heat transfer medium 26 not available. This is drained, for example, or pumped through a suitable conveyor into a separate storage reservoir. In this case, the heat radiation c of the sun passes through the covers transparent to the heat radiation 16 and 18 through and hits the reflective coating 30 , From this, the heat radiation is reflected. This ensures that a building on which the solar collector 10 is mounted, is subjected by the reflected heat radiation c not so strong heating. For example, cooling measures for the building can be reduced or saved. According to another embodiment, not shown, the coating 30 In addition to the reflective properties for the heat radiation and photovoltaic elements include or consist of these. Thus, if necessary, in the absorption mode - as in 2 represented - but in any case in the reflection mode - as in 3 represented - additionally by means of the coating 30 generate electrical energy. This can then, for example, in a supply network with the solar panels 10 equipped building.

The solar collectors 10 are modular, that is, it can also be several solar panels 10 be assembled by series connection and / or parallel connection to a larger solar system. According to the then available effective area of the coupled solar collectors 10 can set the desired amount of heat to be achieved.

10

solar collector

12

receptacle

14

cavity

16 18

limit

20

arrow

22

leader

24

returns

26

Heat transfer medium

28

particle

30

coating

a

solar radiation

b

thermal radiation

c

reflected thermal radiation

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3134865 A1 [0002]
• - DE 2700714 A1 [0002]
• - DE 3537223 A1 [0002]
• - DE 2646174 A1 [0002]
• - US 4790293 [0002]
• - DE 902794 [0002]

Claims (9)

Solar collector with at least one, at least one cavity forming receptacle for a heat transfer medium, wherein the at least one receptacle is connected via a flow and a return to a heat sink in a closed circuit or is connected, characterized in that at least the solar source facing a boundary ( 16 ) of the at least one cavity ( 14 ) consists of a material which is transparent to the solar radiation (a) and the heat transfer medium ( 26 ) is a liquid possessing a high heat-absorbing capacity or a liquid having a high heat-absorbing ability and containing particles. Solar collector according to claim 1, characterized in that the solar source facing away from the boundary ( 18 ) of the at least one cavity ( 14 ) of the receptacle ( 12 ) a for the heat radiation (b, c) reflective coating ( 30 ). Solar collector according to claim 2, characterized in that the coating ( 30 ) within the at least one cavity ( 14 ) is arranged. Solar collector according to claim 2, characterized in that the coating ( 30 ) outside the cavity ( 14 ) is arranged. Solar collector according to claim 2, characterized in that the coating ( 30 ) into the boundary ( 18 ) is integrated. Solar collector according to one of claims 2 to 5, characterized in that the coating ( 30 ) Comprises photovoltaic elements. Solar collector according to one of the preceding claims, characterized in that the receptacle ( 12 ) consists of plastic and / or glass. Solar collector according to one of the preceding claims, characterized in that the heat transfer medium ( 26 ) is a black colored liquid. Solar collector according to one of the preceding claims, characterized in that the inner boundary of the at least one cavity ( 14 ) with a wetting by the heat transfer medium ( 26 ) reducing surface is provided.