GB2104644A

GB2104644A - Inflatable solar collector structure

Info

Publication number: GB2104644A
Application number: GB08214919A
Authority: GB
Inventors: Claude Leroy
Original assignee: Sorelec
Current assignee: Sorelec
Priority date: 1981-08-24
Filing date: 1982-05-21
Publication date: 1983-03-09
Also published as: CH648403A5; CA1193928A; GB2104644B; AR230107A1; ES8305485A1; DE3219951A1; ES514257A0; BR8203272A

Abstract

The inflatable structure comprises a flexible cylindrical casing (1) of plastics material which is transparent with respect in infra-red rays and which is held in shape by an increased internal pressure. Half of the interior surface of the casing is reflecting. Within the casing, there is supported an absorber 17 through which a gaseous or liquid heat exchange fluid may be circulated. <IMAGE>

Description

SPECIFICATION Inflatable heat exchange structure The present invention concerns an inflatable heat exchange structure which permits heat to be both received and emitted, in order to provide either for the production of heat or for the production of cold.

The production of cold by making use of solar radiation is generally effected by means of absorption-type machines in which evaporation of the fluid is maintained by the heat of the sun.

Because of the difficulties which occur in hot countries, with regard to cooling the condenser, in order to heat the evaporator it is necessary to have recourse to concentration- type solar collectors in order to increase the temperature of the evaporator.

However, the efficiency of the installation would be further substantially improved if the problem of cooling of the condenser in hot countries were overcome.

In order to avoid overdimensioning of the exchange surface within dwellings, and in order to achieve a good level of efficiency in regard to the production of cold by an absorption-type refrigeration unit, it is necessary to employ temperatures which occur in the range of average temperatures of between 1 50 and 300"C. In order to achieve such temperatures, recourse is had to collector devices associated with devices for concentrating or focusing the solar radiation, which may be of paraboloid, cylindricalparaboloid, hemispherical or semicylindrical shapes. Such devices must be constantly directed to face towards the sun by a suitable orientation and drive mechanism.

Devices of this type for focusing and collecting solar radiation, which are found on the market at the present time, suffer from many disadvantages.

They are heavy, and they catch the wind to an excessive degree, which puts the orientation mechanisms out of order; the operation of cleaning the reflectors, which is a necessary one, is a tiresome process; the electronic and mechanical device for following the sun is complicated and troublesome because of the weight of the equipment and the fact that the arrangement catches the wind, and uses powerful motors which consume energy; and the transmission mechanisms frequently jam, particularly when there are sandy winds.

The aim of the present invention is to overcome the disadvantages of the known installations and to provide a device for concentrating and collecting solar radiation, which gives a high degree of flexibility in use, which is modularly adapted to the dimensions of the site of use, which lends itself readily to the installation of very large focusing and collection surface areas, which suffers little from being caught by the wind, which has a high degree of reliability, which is very light and which is very easy to transport, while however being of a cost price which is very much lower than the known installations, which also makes it possible both to generate cold and heat using simple, light means which are easy to transport to the location at which they are to be set up, which is relatively compact, which is very easy to maintain and which does not require a great deal of operating power, which provides both for daytime operation, in particular for recovering heat, and for nighttime operation for recovering cold, by the emission of heat.

According to the present invention there is provided an inflatable structure device for providing for heat exchange between a heat exchange fluid and the exterior, including a flexible external cylindrical casing of plastics material which is transparent with respect to infra-red rays and which is held in shape by an increased internal pressure, and a wall provided within said casing, which wall is reflecting in the direction of the external casing and over which flows the heat exchange fluid to be cooled, said fluid being carried to the interior of the casing by way of a feed conduit, to issue by way of a discharge conduit and be recycled by a pump in a buffer reservoir.

The device according to the invention permits a heat exhange fluid to be cooled by natural nocturnal radiation, by virtue of an inflatable structure which can be used in association with solar collectors of inflatable structure type, using the shadow regions cast by the solar collectors, thereby achieving optimum utilisation of the surface on which the sun is shining.

The heat exchange fluid which is cooled during the night by using the above-defined device is stored in a buffer tank or reservoir and is used during the day to cool the condenser of the installations, for example installations for producing cold, using solar energy.

The invention will now be described in greater detail with reference to embodiments which are illustrated in the accompanying drawings in which: Figure 1 is a diagrammatic view in crosssection of the device showing the principle thereof, Figure 2 is a diagrammatic view in crosssection of a first alternative form of the device, Figure 3 is a diagrammatic view in crosssection of a second alternative form of the device, Figure 4 is a view in longitudinal section of part of an inflatable-structrue device for concentrating and collecting solar radiation, and Figure 5 is a view in cross-section of the device shown in Figure 4.

The heat exchange device according to the invention comprises an external cylindrical flexible casing 1 of plastics material which is transparent with respect to infra-red radiation, such as high density polyethylene; the casing is held in its cylindrical shape by a increased internal pressure P1. Disposed coaxially with and within the casing 1 is a flexible cylindrical casing 2 of plastics material, the inside surface of the wall portion of which carries a coating, for example a deposit of aluminium, for reflecting the infra-red rays with respect to the outside casing 1. The second cylindrical flexible casing 2 is held in shape by an increased internal pressure P2 which is higher than the increased pressure P,. Feed conduits 4 are provided to carry a heat exchange fluid (providing calories or 'frigories') to the vicinity of the upper generatrix of the outside casing 1.The heat exchange fluid then flows over the internal cylindrical casing 2 and undergoes heat exchange in the course of such flow, by radiation with the atmosphere through the extenal casing 1 and to exchange infra-red rays with the casing 1, either in a receiving mode or in an emission mode. The heat exchange fluid, after that heat exhange step, collects in the vicinity of the lower generatix of the external casing 1 to be discharged by way of a discharge conduit 5, passes into a buffer tank or reservoir 7 and is recycled by a pump 6 to the conduit 4.

The above-described heat exchange device is entirely static and is very light in weight. It is extremely easy to use and transport since it is inflatable.

The alternative embodiment shown in Figure 2 has a reflecting surface 2 which is directly provided on the lower internal surface of the casing 1.

Figure 3 shows a second alternative embodiment wherein the reflecting surface 2 is provided on an inclined plate in a diameter plane of the casing 1.

Figure 4 and 5 show more detailed views of an embodiment of a device which can be oriented by a control action towards the position of the sun.

The illustrated inflatable-structure device for focusing and collecting solar radiation comprises a concentrating or focusing means 10 formed by a transparent flexible cylindrical casing 11 which is maintained in its cylindrical shape by an increased internal gas pressure P1, using in particular CO2 gas, with the pressure P, being higher than atmospheric pressure. Disposed at each of the ends of the flexible cylindrical casing 11 is a rigid structure 12 to which the casing 11 is seaiingly fixed. The structure 12 is fixed with respect to a trunnion 13 which is freely rotatably carried by a support member 14.Disposed on one of the end structures 1 2 is a pipe member 1 5 provided with a tap to permit the gas for producing the increased pressure P, to be introduced into the casing 11.

Half of the inside surface of the casing 11 is provided with a coating 1 6 for reflecting solar radiation towards the interior of the casing 11.

The coating 16 may be a deposit of aluminium.

The other semi-cylindrical portion of the wall of the casing 11 does not have any coating and remains transparent to the incident solar radiation (see Figure 5).

Disposed coaxially with respect to the concentrating means 10 and fixed with respect thereto is a receiving means 1 7 which is formed by a tube of circular section and which comprises a material which is a good conductor of heat. The outside surface of the wall 1 8 of the receiving means carries a coating for selectively absorbing solar radiation. At each end, the receiving means carries a rigid structure 1 9 which is fixed with respect to an intake or discharge conduit 20.The conduits 20 permit a gaseous or liquid heat exchange fluid to be circulated within the receiving means 1 7. Advantageously, the conduits 20 are in one piece with the axis members 13 of the concentrating means 10 in order to simplify the construction and to ensure that the concentrating means 10 and the receiving means 1 7 are driven in rotation in a fixed relationship relative to each other, and also to simplify the problems in regard to sealing between the movable receiving means 1 7 and the fixed outside installation for recycling of the heat exchange fluid.

The receiving means is of circular cross-section, but it is possible to envisage different receiving means.

Associated with the above-described device is an electronic control and drive device (not shown) for driving one of the axis members 1 3 with a rotary movement, with a very low drive torque, bearing in mind the light weight of the assembly.

The drive force is even lower if, in an alternative embodiment, the device is surrounded by an external casing containing an oil bath on which the internal casing floats.

Claims

1. An inflatable structure device for providing for heat exchange between a heat exchange fluid and the exterior, including a flexible external cylindrical casing of plastics material which is transparent with respect to infra-red rays and which is held in shape by an increased internal pressure, and a wall provided within said casing which wall is reflecting in the direction of the external casing and over which flows the heat exchange fluid to be cooled, said fluid being carried to the interior of the casing by way of a feed conduit, to issue by way of a discharge conduit and be recycled by a pump in a buffer reservoir.

2. A device according to claim 1, in which the reflecting wall surface is a coating on the internal surface of a flexible cylindrical casing which is coaxial with respect to the external casing and in which there obtains a gas pressure (P2 which is higher than the gas pressure (P2) higher than the gas pressure (P1) obtaining between the casing carrying the reflecting surface and the external casing.

3. A device according to claim 1, in which the reflecting surface is formed by a coating on the lower portion of the internal surface of the external casing or an inclined plate on a diametral plane in the external casing.

4. A device according to claim 1 , for concentrating and collecting solar radiation, including a concentrating means forming the external casing, which at each of its two ends comprises a pivot axis member for rotating about its longitudinal axis in end support members, the plastics material casing wall thereof comprising, over a semicylindrical portion, an internal coating for reflecting solar radiation towards the interior, the other semicylindrical portion being transparent with respect to solar radiation, -an internal receiving means which,is coaxial with the plastics material casing, being nonrotatably fixed with respect to said casing, of a material of good thermal conductivity and being provided on its exterior with a coating for selectively absorbing solar radiation, the receiving means being provided at each of its ends with a conduit for the intake or discharge of the heat exchange fluid, and - an electronic control and rotary drive means, for following the movement of the sun.

5. A device according to claim 4, in which the plastics material forming the casing of the concentrating means is stabilised in respect to ultra-violet radiation.

6. A device according to claim 4, in which the reflecting coating within the casing of the concentrating means is formed by a deposit of aluminium

7. A device according to claim 4, in which the increased gas pressure (P,), in particular carbon dioxide gas, which obtains within the concentrating means, is about 200 g/cm2 higher than atmospheric pressure.

8. A device according to any one of claims 4 to 7, in which the receiving means is of circular cross-section.

9. A device according to any one of claims 4 to 7, in which the wall portion of the receiving means is of copper or aluminium, the external surface thereof being anodically oxidised and coloured black.

1 0. A device according to any one of claims 4 to 9, including an external casing containing an oil bath on which the internal casing floats.

11. An inflatable heat exchange structure device for providing for heat exchange between a heat exchange fluid and the exterior, substantially as hereinbefore described with reference to Figure 1, Figure 2, Figure 3 or Figures 4 and 5 of the accompanying drawings.