GB2182076A

GB2182076A - Improvements in greenhouses

Info

Publication number: GB2182076A
Application number: GB08525292A
Authority: GB
Inventors: Orazio Antonio Barra
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-10-14
Filing date: 1985-10-14
Publication date: 1987-05-07
Also published as: GB8525292D0; GB2182076B

Abstract

One at least of the walls of the greenhouse (1), and preferably that which is exposed northwards, is provided with a layer of a thermally insulating material 5 constituting, together with an absorber (3) and a transparent surface 2, a solar chimney (4 and 6), which is put into communication, by means of valves (10, 11, 12), with the ceiling of the greenhouse, with the surface of the ground and with a network of underground pipings (9) for the circulation of the air, three valves permitting: a) the heating of the greenhouse and the transfer to the ground of the heat not-utilized in the greenhouse. <IMAGE>

Description

SPECIFICATION -Improvements in greenhouses It is known that at the basis of present green houses operation, is the utilization of the sun heat and light through the intermediation of large transparent surfaces which let sunrays penetrate inside the greenhouses, thus heating them.

However, the width itself of the transparent surfaces brings with it the consequence that, in some cases, a higher than necessary temperature takes place inside the greenhouse and, in same time, a remarkable heat dispersion in the not-exposed-to-the-sun areas and in the night hours.

In order to obviate these drawbacks, recourse has been made to adjustable openings in the covering surface, to a two-wall lining in order to achieve some thermal insulation, to heating installations utilizing non-solar thermal energy, and so on. These solutions are costly as far as the installation and operating expenses are concerned.

Essentially, the usual problems which arise in relation with greenhouses are the following: a) a stratification of the heat; b) an overheating; c) heat loss due to the large north-oriented transmitting surfaces; d) a temperature's lowering during the night hours.

It is object of the present invention an improved greenhouse which obviates in a very efficient and very economic way the above mentioned inconveniences and which is based upon: -an air circulation, in order to prevent heat's stratification; -the storing in the soil of the superfluous heat which has been collected during the day or insolation's hours, so that the diurnal over heating and the night temperature-fall are avoided; -the reduction of the transparent, low solargain, surface; -the increase of the collecting surface, specially in the areas situated at a latitude exceeding 40 degrees; -the thermal insulation of the north-oriented wall.

The means employed to achieve said results are represented by a system to pick up solar energy, in which the following units are fore seen: an absorber, a conduit for air heated by the absorber, an insulating wall, the whole constituting a so-called solar chimney, and a series of valves and pipings adapted to direct and to choke the hot air flow.

The invention will be better understood by the more detailed description of one of its embodiments, given with reference to the en closed drawing, wherein a greenhouse accord ing to the invention is schematically shown.

With reference to said drawing, a greenhouse according to the invention is provided with a surface 1 exposed to rays of the sun and, therefore, preferably oriented southwards, through which, the sun's heat penetrates inside the greenhouse and is received by a transparent surface 2, which forms, together with the unit 3, absorbing the solar energy, the picking-up complex, that is a space or slot 4 within which the air is heated and sent to the utilization locations. The absorber 3 is, in turn, situated at a certain distance from the transparent surface 2, in such way to form the space or interstice 4, already mentioned, and from an insulating wall 5, in such way to form a second interstice or space 6. The insulating wall 5 is, in turn, lined outwardly by a wall 7, having supporting and protecting functions.

For air circulation, grates are foreseen which are high- and low-placed, as well as a network of underground conduits for the air, the opening and closing of said conduits being performed by means of valves 10, 11, 12 which are manually or automatically operated.

Each valve can take, as one may derive from the drawing, two limit-positions with respect to a center position, these limit-positions being respectively indicated by the sym bols ' and " accompanying the numbers char- acterizing the different valves, that is the positions 10' and 10", 11 and 11", 12 and 12".

According to the position of the valves, the operator will achieve a particular air circulation in the greenhouse, as it will be described in the following.

As one can notice from the abovesaid, a greenhouse according to the invention is in condition to obviate in a simple and safe manner the inconveniences presented by the known greenhouses, without any need for auxiliary apparatuses.

In effects, the air is heated by passing through the spaces or interstices 4 and 6, when the absorber 3 is hit, through the transparent surface 4, by the solar radiation. According to the relative position of the valves 10, 11 and 12, the operator can achieve the following air circuits: valves in the positions 10', 11", 12'; the air circulates, in the return path, within the underground canals 9, transferring the heat which is in excess in the greenhouse to the ground, which in this way performs a function of thermal flywheel, restituting the heat during the night hours.

valves in the positions 10', 11', 12": air circulates inside the greenhouse, avoiding the phenomenon of heat's stratification; valves in the positions 10", 11", 12": the ventilation of the ground is achieved, which is interesting, above all, to control the moisture contents of the ground.

valves in the positions 10', 11', 12': the operator achieves a situation which is essentially similar to the second, above-considered, situation.

valves in the positions 10', 11", 12". By that arrangement of the valves, the pressure in the greenhouse increases in order to balance the pressure values in the solar chimneys 4; such arrangement can, therefore, be used in particular instances, for example when one would like to build greenhouses devoid of a load bearing structure.

-With the valves 10, 11, 12 placed at other possible arrangements, as 10", 11" and 12'; 10", 11' and 12"; or even 10", 11' and 12", the circulation of air would be stopped with a consequent depression taking place in the greenhouse.

Until now, we have spoken of a north positioning of the solar chimney, in order to avoid the heat losses normally due to the glass surfaces which face said cardinal point. One could, however, arrange the solar chimney on the wall of the greenhouse facing the south.

In such a case, the transparent wall 2 of the chimney would be exposed towards the outside of the greenhouse, and the insulating wall 5 would be oriented towards the inside. This solution would permit to install greenhouses in any position, even partially earthed up or completely earthed up, or, anyway in the dark, for particular cultivations, as for instance for the mushroom cultivation, which, as it is well known, need a moist heat condition and very little amount of light.

According to a variant, which is not represented but which is part of the present invention, the various walls forming the solar chimney, may be rendered foldable down to a horizontal position, in order to temporarily create, for particular ambient conditions, a room having a reduced height. For instance, during the night, in order to better keep and utilize the heat emitted by the ground, it is feasible both for a single greenhouse and for a series of greenhouses, to fold the chimney 1-7 in such a way that the greenhouse's space, reduced in its height, can be protected by the insulating material 7. Such insulating material may be also be composed of juxtaposed layers, separately foldable in order to cover a larger area.

Claims

1. A greenhouse, characterized by that one at least of the walls of the greenhouse, and preferably that which is exposed to the north, is provided with a layer of a thermally insulating material constituting, together with the absorber and a transparent surface, a solar chimney.

2. A greenhouse according to Claim 1, characterized by that the, or each, solar chimney is put into communication, by means of valves, with the ceiling of the greenhouse, with the surface of the ground and with a network of pipings, running underground, for the circulation of the air.

3. A greenhouse according to Claims 1 and/or 2, wherein the position of the three valves of Claim 2 permits the heating of the greenhouse and the transfer to the ground of the heat not utilized in the greenhouse; or else the circulation of the air in the greenhouse in order to avoid the stratification of the heat; or also the ventilation of the ground particularly for the control of the ground's moisture.

4. A greenhouse according to one or more of the preceding Claims, wherein each solar chimney can be overturned in particular ambient conditions, as during the night hours, in its whole, in order to reduce the height of the greenhouse and protect it by means of the insulating layer of the chimney itself from an undesired dispersion of the heat.

9. A greenhouse, substantially as hereinbefore described with reference to the accompanying drawing.