DE2600882A1 - Solar energy collector with absorber plate - has selective filter or absorbent layer between first pane and absorber - Google Patents

Abstract

Flat solar energy collector consists of an absorber plate to pass the sun heat to a fluid carrier, with heat insulating cover fitted above the absorber in the form of two spaced transparent panes. There is a selective filter (7) or selective absorbing layer (6) between the first of these panes (5) and the absorber below (1). There is a selective filter. There is a selective filter between the two panes. The selective absorbing layer is applied preferably directly to the absorber. The selective filter should be an infra-red reflecting layer (7) applied to the pane (4 or 5). The selective filter layer (7) should be on the outside of the first pane (5) or the inside of the second (4).

Description

Flat solar panel

The invention relates to a flat solar collector with a Plate-shaped absorber for the transfer of the heat generated by solar radiation on a fluid transport medium and a heat-insulating one attached above the absorber Cover made up of at least two spaced-apart disks made of transparent material.

In such flat solar panels is located between the two cover plates and air between the absorber and the first cover plate.

Solar panels are said to make up the main part of the radiation spectrum of the Convert sunlight into heat and use this as much as possible high Efficiency of a fluid means of transport, e.g. B.

Water, exchange. To achieve a high degree of efficiency Somz collectors have the following properties if possible: a) high absorption (Absorption coefficient ar 2 0.9) in the entire spectral range of sunlight (X = 0.3 to 2 / µm), b) low emission (emission coefficient § <0.2) in the range the thermal radiation (# = 3 to 30 / µm), c) low heat losses through thermal conduction and convection, d) low thermal capacity.

In this context one understands by a selective absorber one that has a high absorption in the area of sunlight and in the area the thermal radiation has a large reflection, and under a selective filter one that has high transmission for sunlight and high reflection for thermal radiation.

There are already known solar collectors with a cover plate, in which the absorber is selective and / or the cover plate is used as a selective filter is trained.

To further reduce convection losses with flat solar collectors the cover should consist of at least two transparent panes. One of those Solar collector is known from a publication by Duffie and Beckman Polar Energy Thermal Processes ", 1974. This well-known solar collector has a selective absorber and two uncoated glass panes. Because glass but is known to be a good heat radiator, the two panes of glass are through Radiation coupled with each other, so that here the komrek tion-reducing effect the multiple panes does not come into its own.

The invention is based on the object of providing a solar collector at the beginning of the type mentioned, in which the radiation coupling between the panes is canceled.

This object is achieved according to the invention in that between Absorber and first pane either have a selective absorber layer or a selective one Filter and a selective filter is located between the first and second discs.

By using a selective absorber layer and / or a or two selective filters it is achieved that only low heat losses through convection appear.

The selective absorber layer is preferably directly on the Absorber, e.g. made of copper or aluminum, applied.

Such a selective absorber layer can be made of metal oxide, e.g. copper oxide or nickel oxide, or made of metal sulfide.

The selective filter is expediently as applied to a pane ultraredreflective layer formed. As ultra-red reflective layers come those made of silver, gold, tin dioxide and preferably tin doped Indiuinoxyd into consideration.

In the case of a solar collector with a selective absorber, the selective Filter layer either on the outside of the first pane or on the inside of the second disc.

When the solar collector is provided with a non-selective absorber is, the selective filter layers are expediently either on the inside of the two panes or on the inside and outside of the first Disc.

The invention will now be illustrated with the aid of some of the drawings Embodiments explained in more detail.

FIGS. 1 to 4 each show a partial view of FIG four different Solulenkoll {gates according to the invention.

The solar collectors each consist of a metallic absorber plate 1, with pipes 2 for a Wännetranportmedium, z. B. water, in contact stand. The pipelines 2 are provided with insulation 3 on their rear side. Above the absorber 1 are two spaced apart glass panes 4 and 5 arranged. Between these two panes of glass 4 and 5 and between the first Disk 5 and the absorber 1 is air.

In the solar collector according to FIG. 1, the absorber 1 is selective Absorber layer 6 applied. The second disc 4 is on its inside with an infrared-reflecting layer 7 is provided.

The solar collector according to FIG. 2 also has a selective absorber layer 6 available. In this case, on the outside of the first glass pane 5, there is an infrared-reflecting one Layer 7 applied.

The solar collectors shown in Figs. 3 and 4 have a non-selective absorber 1. In the embodiment of FIG. 3, both panes of glass 4 and 5 each with an infrared reflective layer on their insides Mistake. In the collector of FIG. 4 there are selective filter layers 7 on the inside and outside of the first pane 5.

Patent claims: Blank page

Claims (5)

Claims: 1. Flat solar collector with a plate-shaped Absorber for transferring the heat generated by solar radiation to a fluid Transport medium and a heat-insulating cover attached over the absorber, those of at least two spaced apart sheets of transparent Material consists, characterized in that between the absorber (1) and the first Disc (5) either a selective absorber layer (6) or a selective filter (7) and a selective filter is located between the first and second disc (4). 2. Solar collector according to claim 1, characterized in that the selective absorber layer (6) is applied directly to the absorber (1). 3. Sormell collector according to claims 1 or 2, characterized in that that the selective filter as on a pane (4 or 5) applied infrared-reflecting Layer (7) is formed. 4. Solar collector with a selective absorber according to one of the previous ones Claims, characterized in that the selective filter layer (7) either on the outside of the first disc (5) or on the inside of the second disc (4) is located. 5. Solar collector with a non-selective absorber after a of claims 1 to 3, characterized in that the selective filter layers (7) on the inside of the two panes (4 and 5) or on the inside and outside of the first disc (5).