DE7620549U1 - SOLAR RADIATION COLLECTOR COOLED WITH A GAS MEDIUM - Google Patents

Description

Interliz Anstalt, Vaduz (Liechtenstein)

Solar radiation collector cooled with a gaseous medium

The invention relates to one with a gaseous medium Cooled solar radiation collector, consisting of a body absorbing sun rays, one on the sun side arranged in front of this body transparent cover plate and a rear side plate arranged behind the body.

Sun radiation collectors that are air-cooled or cooled with another gaseous medium have opposite liquid-cooled collectors have the advantages that their thermal inertia is lower that they have a reduced susceptibility to corrosion and that they are lighter and cheaper to build and easier to install. Furthermore, a simpler one is more aesthetically pleasing Design possible and can therefore do it better and more easily than liquid-cooled collectors in new buildings; or can be integrated into old buildings as a roof or passage element.

The well-known air-cooled solar radiation collectors | consist of a flat box, which is covered on the sunny side with one or more translucent plates. The solar radiation entering the box through this translucent cover is

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June 21, 1976 / Ga

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Γ \ a surface curse that occurs in the form of a divider

absorbent solid body, for example on the blackened surface of a sheet metal plate, absorbed and converted into heat, and the heat generated on the surface of this body is dissipated by an air flow that runs along the surface of the absorbent; Body flows through a gap-shaped space between the translucent cover and the surface of the absorbent body. In addition to these longitudinally _; Flow collectors are also cross-flow air-cooled collectors known, in which the in the aforementioned. Air entering a gap-shaped space behind the translucent cover is passed through a perforated body and flows out of a gap-shaped space behind this body. In the same way as with the collectors with longitudinal flow, the perforated body absorbs the solar radiation on the side facing the sun in these transverse flow collectors, and the perforated formation of the body is intended to do this; serve to obtain a transverse flow through the body and to thereby increase the transfer of the heat generated by the radiation absorption on the sun-side surface of the body to the air flow compared to the pure surface flow along the plate surface of the collectors through which there is longitudinal flow.

The inventive design of an air or gas-cooled Solar radiation collector is primarily because of this characterized in that the absorbent body consists of a

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("\ Absorber layer, inside of which the sun's rays able to penetrate and their zone of energy ·; absorption by absorption of the rays as they pass through

through the absorber layer extends essentially over the 1st

entire layer thickness of the absorber layer and the . is permeable to the gaseous medium and its zone the ^! 'Heat dissipation to the gaseous medium is essentially

extends over the entire layer thickness. With this solar i

The radiation collector thus finds both the absorption of energy through absorption of radiation and the release of heat to the gaseous medium not only at the one facing the sun
Side or surface of an absorbent. Body but inside and practically over the entire _: layer thickness of the absorber layer instead of the several

Can be centimeters. Purely the formation of the absorber layer is significant and it should be noted that the
Radiation portion that is not absorbed in the respective depth of the layer ■ is transmitted and not, for example
is reflected. The absorber layer can, for example ^:

^! _{20. e} i _nem fabrics made of glass, plastic, metal or! Textile fibers consist of or stacked one on top of the other

; Grids made of glass, plastic or metal wire
be or from a filling of random packings, for example
Glass spheres. With the training according to the invention
The collector has three main advantages

I.

· suffices. The heat transfer to the cooling medium is distributed '; , over a much larger area, since the

transition effective surface of the porous absorber layer

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is greater than the heat exchange surface one is equal to I. large plate, so that the heat transfer to the - '

cooling medium result in more favorable conditions. When the flow of the cooling medium hits the
individual pore walls or on the individual; Tissue fibers or fillers that make up the permeable absorber layer are formed every time

thermal boundary layer anew, resulting in an increase j

! the local heat transfer coefficient compared to the heat transfer ^!

speed number leads in the boundary layer flow along a j plate. Through the penetration of the radiant energy
in the interior of the absorber layer, its outer zones have an insulating effect with regard to heat conduction and the heat radiation of that heat to the outside that occurs during passage

is created by the absorber layer in its core, whereby 'the part of the heat that is necessary for the transfer to the
cooling medium is lost, that is, the heat losses; of the collector are reduced. ^:

; With particular advantage, the absorber layer can even be so _; designed 3ein that instead of constant absorption ratios over the layer thickness their absorption capacity
; from the surface facing the cover plate to the interior
; the absorber layer with increasing depth of penetration
ι sun rays rise, preferably in the middle of the
.25 layer thickness of the absorber layer is the largest. this has

the great advantage that «emch. · un der sunny itigen
Above laughs «the Absorbernuhi oh fc a ger.i i \. ■: <■. <\ - '.' J trahlunga-

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ι absorption and heat generation occurs and thereby the ·

j heat loss of the absorber layer or the { ^! Collector can be further reduced to the environment *

! This special absorption profile across the layer thickness

with higher absorption in the middle of the layer thickness than
in the surface zones can be achieved, for example, that uncolored, light-transparent fibers for the surface zone facing the sun

Example made of glass can be used and with increasing j

I depth of penetration of the sun's rays these undyed fibers'

are increasingly mixed with colored fibers or \ color of all fibers is made increasingly darker. Similarly, when using, for example, glass spheres as the absorber layer material, the edge on the sun side can
The absorber layer consists of translucent spheres and.

towards the middle of the layer thickness an increasing proportion of;

ι colored or black balls mixed in or the color j of all spheres must be made increasingly darker. Furthermore can; the desired course of the absorption profile over the '

• '20 layer thickness of the absorber layer also by changing:

the mesh size of the fabric or the match ^; other stratified grids can be achieved by the

Mesh size from the sun-side edge towards the inside of the '

The absorber layer is increasingly being reduced in size. It can also i

I ■ 2 5 the two measures of color change and mesh!

Changes in width can be applied in combination. ^:

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j When the collector is designed as a longitudinal flow Ϊ Collector in which the absorber layer with its solar ! side and with their rear surface on the cover plate or on the rear plate

I.

is, the absorber layer can continue with a capital j

I advantage be designed so that not only the absorption · ^ capacity increases from the surface to the inside of the absorber layer, and also the permeability of the bonders The absorber layer for the gaseous medium increases from the surface to the interior of the absorber layer, so

that preferably in the region of the greatest absorption capacity the flow resistance is the lowest iat. On ; in this way it is achieved that where inside the ! AbBorerschicht absorbs more radiation and generates more heat .15, also more cooling medium flows through and : stronger warned is dissipated, so that the flow profile ; is adjusted over the layer thickness of the absorption profile and an equalization of the temperature of the Flow enters. The change in permeability for the flow can be achieved, for example, by that the absorber layer is built up from several individual tissue or grid layers and the individual layers contain plates perpendicular to the direction of flow, which increase the flow resistance of the individual layer, where, the number of plates per unit length of the individual layer in question from the surface to the interior the absorber layer decreases. Preferably these are

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Panels as thin as possible and transparent to radiation, for example made of glass, to prevent radiation from penetrating:

as little as possible into the interior of the absorber layer hinder. When using, for example, glass balls | for the absorber layer, the permeability can thereby be j be changed so that smaller glass spheres are used for the edge zones than for the interior of the absorber layer.

Depending on the design of the absorber layer, some of the radiation can pass through the absorber layer and

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; 1O hit the back plate. In advantageous? I

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! Way, the back panel can reflect sunbeamersä: ■ · "

^{1 be} trained. This ensures that the

¹ absorber layer for the purpose of penetrating radiation component

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·; Absorption is reflected back into the absorber layer,

| 15 so that the two-fold radiation passage leads to a higher

i total abs οrption and thus a better use of the

j solar radiation leads. According to another advantageous

i In the embodiment, the rear panel can be translucent

Ί be casually trained. That way he can't

j 20 absorbed by the absorber layer during passage

! Radiation component for lighting purposes behind the

j collector is used, which is what happens when using the

i Collector as a roof or passage element of importance and

j can be of great use.

| 25 An advantage of the solar radiation collector according to the invention also consists in the fact that the fabric, one on top of the other, j

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porous grids or spherical bodies
Absorbent layer at the same time a heat insulating loop
forms and the collector thus combines heat recovery with thermal protection, which is what happens when the collector is used
as a Daoh or facade element is important and the
Makes collector useful even in weak or no solar radiation.

Various exemplary embodiments are shown in the drawing
a 'solar radiation collector according to the invention
shown schematically, namely show
Fig. 1 "shows a section through a longitudinal flow

Collector;
FIGS. 2 to 4 three examples of a transverse flow

Collector in section;
Fig. 5 is an enlarged schematic representation of the

Structure of a collector with longitudinal flow in

Cut.

! All illustrated embodiments have on the '■.

! the side of the collector facing the sun a translucent l

! 20 casual cover plate 1 and a back plate 3 »ί

j between which an absorber layer 2 is arranged. Under'

S Use of the materials given as examples is>

j absorber layer 2 of such a porous nature and design ^;

i

j that the suns passing through the cover plate 1 j

J 25 do not radiate on the upper ■ facing the cover plate 1. I.

ι surface of the absorber layer 2 are absorbed, but in ^!

ι;

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penetrate the interior of the absorber layer 2 and the j absorption of solar radiation extends as far as possible over the entire j layer thickness of the absorber layer 2. The ₍ not yet absorbed at a! Respective depth of the layer thickness

Part of the radiation is therefore not reflected, but

t is transmitted, so that this radiation component can penetrate even deeper S into the layer and then progressively
to be absorbed. For this purpose are particularly suitable
Conveniently fiber fabric or layered grids or
Spherical fillings made of glass, which according to the

desired absorption ratios over the layer thickness j the absorber layer can be colored. Simultaneously ! is the absorber layer 2 due to the porous nature; ness and training over their entire layer thickness for the permeable gaseous medium, so that in all depths of the

Layer thickness of the radiation component absorbed there ' in the form of heat with a high heat transfer coefficient to the gas!

I ; shaped medium is transferred and discharged from the medium

' will. Due to both radiation absorption and dexf | 20 heat transfer to the gaseous medium over the entire! '. The layer thickness of the absorber layer is proportionate

small dimensions of the collector a very high total «I

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absorption and use of incident solar radiation j J possible, whereby the absorption inside the absorber layer also causes heat losses through radiation or radiation 'ι

line through the cover plate 1 to the environment very little

. are held. In the embodiment of Fig. 1, the absorber layer 2 is located with its sun-side and back \

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( ^χ side surface on the cover plate 1 or; on the rear side plate 3 and the absorber layer 2 is traversed by the gaseous medium in its longitudinal direction.

flows. FIG. 5 shows this j through which there is longitudinal flow

Collector in an enlarged schematic representation

Absorber layer 2, which is made up of several overlaying layers

Teten tissue or grid layers is built up. j For example, by coloring the ί differently Individual layers, the individual layer adjoining the cover plate 1 being highly translucent and the ' underlying individual layers an increasingly darker f

getting color can be achieved that; Absorption capacity of the entire absorber layer from the! to the surface adjacent to the cover plate 1 to the inside

the absorber layer rises so that inside the

Absorbent layer absorbs more radiation and more heat

ί is generated than in the area of the surface of the absorber J

layer 2. To achieve that, accordingly, the

Mass flow of the gaseous medium from the surface to the ^; The inside of the absorber layer becomes stronger
Embodiment of FIG. 5 with the individual layers
plates 7 directed transversely to the direction of flow,
where the number of plates per unit length of the

, top single layer towards the inside of the absorber layer 2! decreases, so that accordingly the artificial flow resistance generated with the plates 7 j from the top ^! Single layer to the deeper lying single layers

gets smaller.

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In the embodiments of FIGS. 2 and 3 are located between the cover plate 1 and the absorber layer 2 on the one hand and between the absorber layer 2 and the Rear side plate 3, on the other hand, differently designed air gaps. The absorber layer 2 is in both Cases with a uniform direction of flow across the j

i gaseous medium flows through it. In the case of the j

The example of FIG. 4 is the collector through bulkheads 6 j subdivided so that the absorber layer 2 in alternating j directions of flow of the gaseous medium across j is flowing. !

In all of the illustrated embodiments, the · ^;

^: Rear panel 3 available in three different versions!

be leading. The back plate 3 can have a high '

Have absorption capacity for solar radiation, so that '

the portion of radiation that passes through the absorber layer 2 j

if necessary goes right through it, on the back: plate 3 is absorbed and converted into heat, which '. · {·

, by heat conduction to the absorber layer 2 through J

flowing medium passes over. The back plate 3 can advantageously be designed so that it has a high. \ Has reflectivity for solar radiation. This throws

the proportion of the radiation that may pass through the absorber layer in the first radiation passage, j . 25 reflected from the back plate 3 to the absorber layer, and absorbed in a second beam path in the interior of the absorber layer 2. In this way, in the case of

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1 'moderately small layer thickness of the absorber layer a high:

\ Total absorption can be achieved. As a third option ^!

1: · the back plate 3 can be made translucent ^;

i '

} be. This training is particularly suitable, for example

k 5 when using the collector as a roof element to the

4 I.

] Radiation component that, depending on the design of the absorber ₍

I layer goes right through the absorber layer!

ί to let the back plate 3 emerge and behind the j

j i

; To use the collector for lighting purposes. In particular;

10 also in this case the collector according to the invention has the ' Advantage that the porous absorber layer 2 is a thermal insulation? forms a layer which, in addition to heat recovery, through: Radiation absorption also reduces room heat losses and provides thermal protection. :

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Claims (1)

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• I I - (H C. U ■ i · »W ........ ,, .. f 13th U S. η S. r C. H Solar radiation collector cooled with a gaseous medium, Consists of a body that absorbs the sun's rays, one in front of this body facing the sun translucent cover plate and a rear side plate arranged behind the body, characterized in that that the absorbent body consists of an absorber layer (2), in the interior of which the sun's rays able to penetrate and their zone of energy! absorption, by absorption of the rays as they pass through ' the absorber layer extends essentially over the entire; i layer thickness of the absorber layer and that for the < i gaseous medium is permeable and its zone of heat ' release to the gaseous medium is essentially via j i extends the entire layer thickness. ! Solar radiation collector according to claim 1, characterized in that j shows that the absorber layer is formed so that J their absorption capacity from that of the cover plate tensile j returned surface to the inside of the absorber layer with i increasing penetration depth of the sun's rays, \ preferably in the middle of the layer thickness of the absorber ■ layer is the largest. j 3. Solar radiation collector according to claim 2, characterized in that ' shows that the absorber layer with its sun-side: 7620549 12/22/77 Γ »» »" ItHIMfM I · «· · f« II • Me · ^Γ · ·> * ' ^: and rear surface on the cover plate and on the Back plate rests and in its longitudinal direction of
- The gaseous medium flows through and that the
\] Permeability of the absorber layer for the gaseous
; j - 'medium from the surface adjacent to the cover plate : the absorber layer to the middle area of the layer thickness increases, preferably in the area of the greatest absorption capacity, the flow resistance is lowest. 4. Solar radiation collector according to one of claims 1 to 3 ^ ί characterized in that the back plate (3) | Is designed to reflect the sun's rays. ] '■ ι 5 · Solar radiation collector according to one of Claims 1 to 3 »' characterized in that the back plate (3)! is designed to be translucent. j 7620549 12/22/77