GB2031580A

GB2031580A - Utilizing natural energy to heat a double-walled structure

Info

Publication number: GB2031580A
Application number: GB7837086A
Authority: GB
Original assignee: NOVEX FOREIGN TRADE CO Ltd
Current assignee: NOVEX FOREIGN TRADE CO Ltd
Priority date: 1978-09-15
Filing date: 1978-09-15
Publication date: 1980-04-23
Also published as: GB2031580B

Abstract

Solar energy and ground heat are utilised in a structure having a double- walled foil covering (3,4) transparent to solar radiation by spraying ground (well) water at superatmospheric pressure into the space between the two foil covers to provide frost-free conditions within the structure, the water subsequently being returned to the ground. <IMAGE>

Description

SPECIFICATION Process and apparatus for the utilisation of solar and geothermal energy in constructions with double-walled covering Background of the invention Field of the invention The invention concerns a process for the utilisation of solar and geothermal energy in constructions with double walls, covering or cladding and an apparatus for the performance of the process.

Description of the prior art The use of foil-ciad greenhouses heated by external sources of energy e.g. by thermogenerators, is increasingly widespread in agriculture when a low ambient temperature and insufficient sunlight justifies such an application. Foil-clad constructions heated by thermogenerators allow the early planting of certain plants, but the high investment and operating costs involved make economic operation doubtful in many cases, or cause the proce of plants produced this way to be rather high. For instance, considering a heating installation of 15-t capacity, the operating costs of heating by thermogenerator over a season (crop cycle) amount to 30-40 Forints (Hungarian currency) per sq.m. It is a characteristic of investments costs that for every hectare of production area 10thermogenerators are required.

According to a known solution for the improvement of the heat insulation of constructions with double covering, water is caused to flow through the space between the skins of the double covering and the special water run tracks and baffle plates are used to maximise the foil area covered by water.

Such experiments have also been carried out with greenhouses. It is also a known concept to let water flow between a double foil layer. This solution or this method has, however, considerable drawbacks; such as the need to use baffles etc. which makes a practical application of this method virtually impossible. In addition, the flowing water could not provide the required heat efficiency.

Summary of the invention An aim of the invention is to eliminate the aforementioned drawbacks of known foil covered constructions and to provide a process and apparatus whereby the inherent heat of the ground (soil) is utilised for heating constructions with double walls, covering or cladding.

The invention is based on the discovery that the above aim can be achieved if the water is obtained from the ground and sprayed at a given temperature into the space between the double foil.

According to one aspect of the invention, therefore, there is provided a process for the utilisation of solar and geothermal energy in constructions with double walls, covering or cladding wherein water is passed into the space between the two layers or skins or foils of a structure that is erected on the ground surface; the essence of the invention is that the water is pumped or otherwise obtained from the ground and transferred at a given temperature by spraying to the inner foil (layer, skin) at a superatmospheric pressure, i.e. a humid atmosphere is created in the space between the foils (layers, skins) by the spray effect and then the water is collected at the bottom of the space between the two foils etc.

and recirculated into the ground.

Naturally, the quantity of the water to be sprayed has to be controlledly varied in dependence on the ambient temperature.

The essence of the apparatus for the performance of the process is that closed ducting and spraying elements are used for the feeding of water into the space between the two foil layers etc. and the collected waer is channelled into a device for returning the water into the ground. The device for recirculating the water into the ground is preferably a drying basin.

Our experiments have proved that the investment and the operation of the construction according to the invention are very economical. Thus e.g. for every hectare of productive area it is sufficient to provide six wells, each with a capacity of 5 hectolitres, and six pumps.

In our invention, 15-35 hectolitres of water per hectare per minute are required. In such a case, frost-free conditions will prevail inside the construction at ambient temperatures of - 1 0 C to --250C, assuming the temperature of the water to be 13"C which cools down to 2"C - 3"C in the space between the two foils.

In the construction or plant according to the invention, the inherent ground heat, the "cave effect" of the ground heat, as well as the thermal energy of the water and solar radiation can all be utilised with the aid of the water sprayed in. The utilisation of the heat energy of the water and the heat energy of the ground transferred to the water does not require any other external energy source, apart from the one for operating the pump.

Brief description of the drawing The invention is described, by way of example only by reference to a preferred embodiment illustrated in the accompanying, purely schematic drawings, wherein: Figures 1 and 2 show diagrammatic cross-sections of a construction with two foil covers according to the invention.

Description of the preferred embodiment The construction according to Figure 1 consists of an innertubularframe 1 and an outer tubular frame 2, both anchored to the ground. The inner frame 1 is covered by a foil cladding 3 and the outer frame 2 is covered by a foil cladding 4. The outer foil cladding 4 is fastened at the bottom by compacted soil heaped on it and the inner foil cladding 3 is fastened by a water-collecting channel 10 secured to the inner frame 1. A pipe line 5 runs through the whole length of the construction at the top of the space formed by the two foil claddings, along the ridge line. In the pipe line 5 spraying elements, in the described embodiment, spray heads 6 are arranged at a suitable spacing from one another.Pipe line 5 is connected by a vertical pipe and a collector pipe not shown in the drawings to one or more tubular pumping well(s) or to the delivery side of a pump 7 connected to the pumping well(s). Pipe lines 9 are connected to the delivery side(s) of pump(s) 7.

The drive motor(s) 13 of pump(s) 7 are included into the control circuitry of a temperature-sensor measuring the ambient temperature in such a way that when the ambient temperature falls, more and more additional pumps are switched on so that more and more water is pumped into pipe line 5 and the spray nozzles 6 for spraying. The water running down the inner foil cladding 3 in the form of a water curtain is collected bythe collector channel 10 whence the water is transferred by a collector pipe not shown in the drawings - and via the pipe line 11 into a drying basin 12. It is understood, that depending on their relative absorbinb capacities, more than one drying basin may be required for a particular plant or installation.

As can be seen from the description so far, only the operation ofthe pump(s) 7 requires an energy input in order to feed water from a selected layer in the ground into the space formed between the two foil covers. In this way, on the one hand the heat stored in the ground can be utilised through the water lifted from below the ground surface, on the other hand a "cave effect" is generated on the surface of the ground covered by the construction.

The double foil-cladding and the water curtain provide excellent heat insulation in relation to ambient atmosphere and at the same time, this kind of insulation is permeable to solar radiation, thus rendering the utilisation of solar energy possible.

Figure 2 is a simplified schema of Figure 1 to show that as water is sprayed out from the spray heads 6 and runs down in the direction of the arrows 16, it will cover increasing annular areas 14,15.

The process and apparatus according to the invention have been applied mainly in the form of a foil tent, which can also be used in constructions for the purpose of keeping livestock etc. in which case not even pumps are necessary.

Depending on the relation between the utilised water and the ambient temperature the apparatus according to the invention can alternatively be applied for heating or cooling.

Claims

1. A process for utilisation of solar and geothermal energy in structures with double covering, in which water is supplied into the space defined between the two covers, the structure standing on the ground surface, wherein the water is obtained from the ground and is sprayed to the outer surface of the cover at a suitable temperature and pressure to create a humid atmosphere in the space between the two covers, the water being collected at the bottom of the said space between the two covers and recirculated into the ground.

2. A process according to claim 1 wherein the water is sprayed into the said space at superatmospheric pressure.

3. A process according to claim 1 or 2 wherein the quantity of water sprayed into the said space is controlled in dependence on the ambient temperature.

4. A process according to any preceding claim wherein said covers are foil covers.

5. Apparatus for carrying out the process according to claim 1 comprising a structure with a double covering, a device for supplying water into the space defined between the two said covers, and a device for collecting the water from said space, wherein the said device for said space consists of a plurality of spraying elements arranged in a closed pipeline connected to a tubular well, and the device for collecting the water consists of a channel and a recirculating element for returning the water into the ground is connected to said channel.

6. Apparatus according to claim 5 wherein said collector is a drying basin.

6. Apparatus according to claim 5 wherein the closed pipeline includes at least one pump.

7. Apparatus according to claim 5 or 6, wherein a drying basin is provided for returning the water into the ground.

8. A process according to claim 1 substantially as herein described with reference to and as shown in the accompanying drawings.

9. Apparatus according to claim 5 substantially as herein described with reference to and as shown in the accompanying drawings.

New claims or amendments to claims filed on 12th December 1979 Superseded claims 1 and 4-7 New or amended claims:

1. A process for the utilisation of solar and geothermal energy in a plant cultivation enclosure having two spaced apart walls made of a material that is permeable to solar radiation, said enclosure being continuous and being supported on the ground, the said process comprising establishing a non-recirculatory ground water flow system between the said walls, including pumping ground water in the physical and chemical state and at the temperature at which it is obtained from the ground to the space between said walls and spraying it onto the outer surface of the inner wall at an elevated horizontal plane so that the water flows downwardiy in said space, collecting the water at the bottom of the said space, and allowing the thus collected water to pass back into the ground, whereby the sole external source of power utilised in the process is the means used for said pumping.

4. A process according to any preceding claim wherein the said material is a synthetic foil.

5. Apparatus for the utilisation of solar and geothermal energy comprising a plant cultivation enclosure having two spaced apart walls made of a material that is permeable to solar radiation, said enclosure being continuous and being supported on the ground, and a non-recirculatory ground water flow system established between the said walls, said system including ducting, pumping, means in said ducting for pumping ground water in the physical and chemical state and at the temperature at which it is obtained from the ground to the space between said walls, spraying means located at an elevated horizontal plane in said space for directing sprays) of water on the outer surface of the inner wall so that in use the water flows downwardly in said space, and a water collector for collecting the water at the bottom of the said space from which the collected water can be passed back into the ground, whereby the sole means of the apparatus requiring a supply of external power is the said pumping means.