GB2037421A

GB2037421A - Heat accumulator

Info

Publication number: GB2037421A
Application number: GB7941088A
Authority: GB
Original assignee: VELDHOEN ISOLATIE BV
Current assignee: VELDHOEN ISOLATIE BV
Priority date: 1978-11-30
Filing date: 1979-11-28
Publication date: 1980-07-09
Also published as: FR2443027A1; NL7811770A; DE2948099A1; BE880232A

Abstract

A heat accumulator for the storage of energy comprises a mass of material (2), such as clay or chemical waste, situated in the soil and thermally insulated from the surrounding mass of soil by an insulating layer (3). The layer (3) comprises a plurality of separate thermally insulating boards (4). Each board (4) comprises a sheet of thermally insulating material (6) completely enclosed by a water tight foil layer (7). In a preferred embodiment, the layer (3) comprises at least two layers of boards (4) wherein the boards of one layer are staggered relative to the boards of the other layer. <IMAGE>

Description

SPECIFICATION Heat accumulator The invention relates to a heat accumulator for the storage of energy.

A heat accumulator is known which comprises a mass of material situated in the soil, the mass of material being thermally insulated from the surrounding mass of soil by an insulating layer consisting of a single layer of insulating material enclosed by a watertight foil layer.

The use of alternative energy sources, in particular solar energy, has been on the increase for some time. Solar energy, however, is not available continuously, and therefore it is advantageous to store in suitable manner part of the energy produced during periods of intense solar radiation.

For this purpose a heat accumulator of the above mentioned kind may be used. In this known heat accumulator the insulating layer consists of a continuous layer of insulating material both sides of which are clad with a continuous watertightfoil layer. The foil layers serve to keep the layer of insulating material free of moisture, as the insulating material looses its thermal insulating properties when the material becomes wet.

The disadvantage of this known heat accumulator is that when the foil layers are locally damaged the entire continuous layer of insulating material will become wet whereby the insulation of the heat accumulator with respect to the environment will be reduced.

The foil layers may be damaged by, for example, a root of a tree, or may tear upon activity of the surrounding mass of soil. This may be prevented by, for example, providing a support structure of concrete which, however, would raise the costs of the heat accumulator considerably.

The invention provides a heat accumulator for the storage of energy comprising a mass of material situated in the soil and thermally insulated from the surrounding mass of soil by an insulating layer, the insulating layer comprising a plurality of separate insulating boards, each of which comprises a sheet of insulating material completely enclosed by a foil layer.

Thus, a heat accumulator may be provided wherein the insulation with respect to the environment will be reduced only slightly when the insulating layer is locally damaged. Moreover, there is no need to provide a support structure for such a heat accumulator. Furthermore, the required insulating boards may be mass produced so as to decrease the costs of the heat accumulator.

Advantageously the insulating layer comprises at least two layers of mutually shifted insulating boards. In this manner, cold transmitting bridging paths are substantially avoided.

Preferably, a continuous watertight layer is provided on the inner side of the insulating layer.

This prevents an eventual ground water displacement through the heat accumulator and also a vapor diffusion from the heat accumulator to the surrounding mass of soil.

The surface area of each insulating board may be substantially 60x 120 cm2.

Then, in case of damage to the foil layer, only a small proportion of the insulation of the heat accumulator will be lost, while nevertheless the heat accumulator may be constructed in a relatively short time.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 is a schematic sectional view of our embodiment of a heat accumulator according to the invention.

Fig. 2 is a sectional view of part of the insulating layer of Fig. 1 illustrated on an enlarged scale.

Referring to Figure 1 , the heat accumulator shown therein comprises a mass of material 2 situated in the soil, said mass consisting of clay, chemical waste material or the like. The mass of material 2 is thermally insulated from the surrounding mass of soil by an insulating layer 3.

The insulating layer 3 comprises two layers of insulating boards 4, the boards of one layer being shifted or staggered with respect to the boards of the other layer as illustrated in Fig. 2. In this manner cold transmitting bridging paths along the boundary plane 5 between two adjacent insulating boards 4 are substantially eliminated.

Each insulating board 4 comprises a sheet of insulating material 6 completely enclosed by a watertight foil layer 7 consisting of polyethylene, for example, a material having good properties for acting as a vapor barrier. Another suitable kind of material for the foil layer 7 is polyvinylcholoride.

The insulating material 6 may consist of a suitable synthetic material having favourable insulating properties like polystyrene, polyurethane or foamed polyisocyanurate.

The bottom surface of the heat accumulator 1 may be 25 x 25 m2, for example, and the height may be about 6 m, while the upper surface is situated about 2.50 m below the surface of the earth. Preferably, the surface area of each insulating boards is substantially 60 x 120 cm2.

The heat accumulator 1 thus may be constructed relatively quickly, and when an insulating board is locally damaged, the insulation of the heat accumulator 1 with respect to the environment will be reduced only slightiy. Also activity of the soil can be easily accommodated by the loose structure without generating large cold transmitting bridging paths.

The heat accumulator 1 is provided on the inner side with a continuous watertight foil layer 8. This, prevents an eventual ground water displacement through the heat accumulator 1 and also vapor diffusion from the interior of the heat accumulator 1 to the environment.

A plurality of tubes, schematically indicated by the dotted line 9, are disposed in the heat accumulator 1. Vertically, the tubes are arranged at a plurality of levels in loops and adapted to supply and withdraw heat to the heat accumulator 1. The energy supplied, for example, is produced by a solar collector 10 disposed on the roof 11 of a house 12. The energy heats a quantity of water that is pumped through the heat accumulator 1 by a pump (not illustrated) and delivers its heat thereto. When heat is required and the solar collector 10 cannot supply energy, heat may be taken from the accumulator 1 by feeding cold water to the heat accumulator 1. Of course, other sources of energy also may be used to elevate the temperature of the heat accumulator 1.

Furthermore, measuring and controlling means 13 are provided and coupled to the heat accumulator 1 via a cable 14. In the embodiment illustrated in the drawing, the means 1 3 are located in a small measuring house 15, but said measuring and controlling means 13 also may be situated in the house 12. By the use of the means 1 3 the condition and the operation of the heat accumulator 1 can be controlled. The pump pumping the water from the solar collector 10 through the heat accumulator 1 has to be deenergized, when the temperature of the solar collector 10 falls below that of the heat accumulator 1.

The invention is not limited to the embodiment disclosed herein-before but various modifications thereof are possible within the scope of the invention.

Claims

1. A heat accumulator for the storage of energy comprising a mass of material situated in the soil and thermally insulated from the surrounding mass of soil by an insulating layer, the insulating layer comprising a plurality of separate insulating boards, each of which comprises a sheet of insulating material completely enclosed by a foil layer.

2. A heat accumulator as claimed in claim 1, wherein the insulating layer comprises at least two layers of mutually shifted insulating boards.

3. A heat accumulator as claimed in claim 1 or claim 2, wherein a continuous watertight layer is provided on the inner side of the insulating layer.

4. A heat accumulator as claimed in anyone of the preceding claims, wherein the surface area of each insulating board is substantially 60 x 120 cm2.

5. A heat accumulator for the storage of energy, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

6. An insulation board for a heat accumulator of anyone of the preceding claims, the board comprising a sheet of insulating material completely enclosed by a foil layer.