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Title:
CHIMNEY ENERGY CONVERSION SYSTEM
Document Type and Number:
WIPO Patent Application WO/1994/027044
Kind Code:
A2
Abstract:
An energy conversion system which includes at least one chimney having an up-run following the contour of a hill side, the chimney having a lower air inlet and an upper air outlet, means for effecting a flow of air from said inlet to said outlet, an engine associated with the chimney, and drive means for the engine arranged for operation by the air flow so that energy of the air flow is used to drive the engine characterised in that part of the up-run is an excavated length of the hillside.

Inventors:
Senanayake
Daya
Ranjit
Application Number:
PCT/IB1994/000100
Publication Date:
November 24, 1994
Filing Date:
May 09, 1994
Export Citation:
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Assignee:
Senanayake
Daya
Ranjit
International Classes:
F03D9/00; (IPC1-7): F03D1/04; F03D3/04
Foreign References:
US3436908A1969-04-08
GB1519774A1978-08-02
FR675981A1930-02-17
EP0003185A21979-07-25
US4359870A1982-11-23
US4453383A1984-06-12
US4319141A1982-03-09
US4801811A1989-01-31
GB2055980A1981-03-11
Other References:
BRENNSTOFF-W{RME-KRAFT, vol.35, no.12, December 1983 pages 522 - 525 TH.MAHLBACHER 'Technikgeschichtlicher r}ckblick zu "alternativen energiequellen".'
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Claims:
CLAIMS
1. An energy conversion system which includes at least one chimney having an uprun following the contour of a hill side, the chimney having a lower air inlet and an upper air outlet, means for effecting a flow of air from said inlet to said outlet, an engine associated with the chimney, and drive means for the engine arranged for operation by the air flow so that energy of the air flow is used to drive the engine characterised in that part of the uprun is an excavated length of the hillside.
2. An energy conversion system according to Claim 1 characterised in that the chimney includes a segment substantially flush with and opening out onto the hill side contour, and in that fabricated closure members cover the opening.
3. An energy conversion system according to Claim 2 characterised in that a closure member includes a pivoted flap hinged to allow impinging wind to enter the chimney.
4. An energy conversion system according to Claim 3 characterised in that the flap is angled to deflect the wind upwardly.
5. An energy conversion system according to Claim 2 characterised in that the chimney segment subtends a minor proportion of the circumference.
6. An energy conversion system according to Claim 1 characterised in that the chimney is circular in cross section throughout its length.
7. An energy conversion system according to Claim 1 characterised in that the chimney inlet is in communication with the underside of a glass collector roof, whereby air from said underside of the roof can flow through said inlet and enter the chimney.
8. An energy conversion system according to Claim 5 characterised in that said collector roof overlies a heat sink, and in that a control unit limits the said rate of flow of air through said inlet.
9. An energy conversion system according to Claim 8 characterised in that said heat sink includes rubble from the hill side.
10. An energy conversion system according to Claim 1 characterised in that a starter unit effects initial air flow upwardly of the chimney, said starter unit being operable also to supplement subsequent upward air flow whereby to maintain engine output.
11. An energy conversion system according to Claim 1 characterised in that the said chimney segment has a horizontal dimension greater than lm and the chimney has a minimum diameter of 2m.
Description:
CHIMNEY ENERGY CONVERSION SYSTEM

FIELD OF THE INVENTION

This invention relates to an energy conversion system.

Also disclosed is an atmospheric power dam utilised to provide an air current whereby to drive an engine such as an electricity generator and/or to remove air already used to drive an engine.

The terms "upper" and "lower" are used in this specification in relation to the earth's local gravitational direction.

BACKGROUND TO THE INVENTION

The energy conversion system of the invention includes a chimney having a lower inlet and an upper exit, means to induce air flow from the chimney inlet to the chimney outlet, and an engine associated with the chimney to be driven by said air flow.

Usefully the engine is an electricity generator, of an output suitable for supplying electrical power to a national grid. The chimney can have more than one associated engine, respectively alongside or within the chimney; and there can be more than one chimney for driving one engine, as by one or more sets of rotatable blades, perhaps of different sizes and/or shapes, in the air flow path.

The rising air flow or air current can be produced or added to by a temperature difference between the lower and upper chimney mouths, and by a barometric pressure difference. Furthermore the rising air current can be provided by or added to using an external wind arranged in known fashion to pass across the upper exit and/or by the use of the herein disclosed atmospheric power dam. The power dam can be used to remove air slowed after its passage past the engine drive.

In preferred arrangements of this invention, natural features such as large height differentials between mountain tops and valleys, and topographical features such as canyons and cliffs are used. Their location is preferably selected so that there is a height difference between the chimney exit and chimney mouth of approximately 2,000 metres (usefully available between the chimney exit at or adjacent the top of the mountain or cliff and a

chimney inlet at or adjacent the base of the mountain, though the inlet or one of them can be part way up a mountain) . The system of the invention can however be used with height differentials in the range 20 metres to 10,000 metres.

DESCRIPTION OF THE PRIOR ART

A system for utilising the energy of a moving air current is disclosed in GB 2,055,980A, showing a chimney through which an air current is induced by barometric or temperature differences, and/or by wind passing over the top of the chimney. Several chimneys may be provided; one disclosed chimney is of height 24 metres, laid on a slope or against a brick-built structure. The rotor of the engine may be installed in the chimney, in the air flow path.

USA Patent 3,945,218 discloses an upflow vapour conduit laid onto a mountain side, but for an environmental control system. The conduit is insulated, to inhibit premature condensation. The system is suggested as suitable for the geographical area of Pikes Peak, utilising the available differential height of about 3000m.

STATEMENT OF THE INVENTION

We now provide an energy conversion system which includes at least one chimney having an up-run following the contour of a hill side, the chimney having a lower air inlet and an upper air outlet, means for effecting a flow of air from said inlet to said outlet, an engine associated with the chimney, and drive means for the engine arranged for operation by the air flow so that energy of the air flow is used to drive the engine characterised in that part of the up-run is an excavated length of the hillside.

In a preferred embodiment the up-run has an opening substantially flush with the hill side contour i.e. the ground surface, the outwardly directed opening being covered by fabricated closure members. Usefully the up-run (other than the opening and closure members) is circular in cross-section, with the opening subtending a minor proportion of the circumference.

The chimney has a minimum diameter of 2m.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described, by way of example, with reference to the accompanying drawings, in which:-

Fig.l is a side section of one embodiment of the invention;

Fig.2 is a front view of the embodiment of Fig.l;

Fig.3 is a perspective view of a power dam unit; and

Fig.4 is a perspective view of the embodiment of Fig.l with power dam units fitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A construction starting point at or near the top of a mountain 10 is marked 1 in Fig.l.

From this starting point, a large diameter excavation 2 is commenced. The excavation is in this embodiment 500 metres in diameter. The excavation is preferably carried out from the top down, along the side or contour of the mountain to its base. The excavation substantially follows the angle of the mountain side, selected so that the resulting hollowed chimney conduit will have no bends (or in an alternative embodiment bends only of large radius).

The excavation is generally circular in cross-section throughout its length, but has a sector which breaks through to the ground surface so that the resulting conduit has at least its major circumference of circular cross-

section, but with one side 3 (in this embodiment of 30 metres width) being open outwardly along an upward run.

During construction, the open side 3 can be used for tipping over or dumping the smaller rubble, from final smoothing of the drilled or excavated rock. As described below the rubble need not be removed, or more usually need not be removed a great distance, which can be a considerable advantage.

After completion of the excavation the open side 3 is closed by a fabricated structure as described below, whereby to form an upwardly extending chimney, largely or wholly below ground level. Preferably the fabricated structure is at least partly removable, for any inspection and maintenance required, though one advantage of the disclosed arrangement is its potential long uninterrupted life.

The rubble 4 from the excavation is spread at the bottom of the mountain 10, for use as a solar heat collecting layer adjacent the inlet to the chimney. In this embodiment the rubble is spread over a surface area extending 2000m along the base of the mountain, to cooperate with a chimney inlet of the same length; in an alternative embodiment the chimney inlet is of lm width, with the inlet air already confined whereby to enter through the chimney inlet at a

substantial flow rate. The rubble is spread at a location unaffected by chance rubble movements e.g. by broken rocks which may fall from the hill side.

In this embodiment, a glass collector roof 5 to overlie the spread rubble is constructed at the mountain base to connect with the excavated shaft 2. This roof 5 is preferably multiple e.g. double-glazed, with a gentle curve to reduce air flow (friction) losses adjacent the bottom of the excavated shaft 2. The rubble thus form a heat sink, solar heated, available to help maintain the upwards air flow in the chimney i.e. to maintain a temperature differential between the chimney inlet and outlet.

The underside of the roof 5 is connected to the chimney, whereby to direct heated air through a chimney inlet. The rate of flow can be determined by a control unit, whereby to maintain substantially constant the engine rotational speed, if this be the required operational characteristic.

One or more wind turbines 6 are mounted at or near the base of the shaft excavation 2, to be driven by the air flow.

In this embodiment a flexible cover 7 is fixed across the open side 3, after completion of the excavation work. Each such cover provides an ancillary input, part way up the chimney.

The flexible cover 7 comprises a frame with hinged panels to which are fixed counterweights (or similar) weighted to hold the panels normally in a closed condition, but so as to allow the panels to be blown inwards by a wind having a force above a predetermined threshhold level whereby to deflect the wind upwards and towards the upper (exit) end of the shaft 2. The flexible cover 7 acts as a dam and converts the shaft excavation 2 into a wind tunnel 8 (or chimney). The flexible cover includes flaps 11 hinged to pivot inwards of the chimney to permit impinging wind to enter the chimney; as shown the flaps both deflect the impinging wind upwardly an inhibit air loss through the cover.

Although shown in this embodiment to be operated automatically by wind pressure against a counter-weight, in an alternative embodiment the degree and speed of flap opening can be controlled by sensors, or manually, in accordance with the existing chimney updraught, whereby to control engine output.

Whilst the flexible cover and power dam will usually be downstream of the engine (higher in the tunnel) so as to help remove otherwise stagnant air which has already given up energy to the engine, in an alternative embodiment it can be upstream of the engine, whereby to supplement the

air current or in consistently windy regions to be the prime source of the air current.

One arrangement operates as follows. Due to the large height differential, a natural temperature difference exists between ambient atmospheric air at the base and at the top of the mountain. The general worldwide standard atmospheric average temperature is a drop of 6°C for every 1,000 metres in height. Initially, an air flow is induced by artificially heating air at the top of the wind tunnel 8, and which can subsequently also be used if necessary to supplement the chimney air current resulting from the heat store provided by the ground rubble e.g. during non- sunlight hours).

This auxiliary heating creates an initial air flow through the wind tunnel 8, drawing hot air from the base level into the chimney inlet. As the hot air rises, a continuing atmospheric "cycle" is created, and this continuing air flow is used to drive the turbines 6.

The glass collector roof 5 effects warming of the air at the chimney base, before that air enters the wind tunnel 8 and so provides additional heat and power.

The main advantages of this invention are:

1. The use of natural atmospheric temperature diffentials which exist at various height differentials on the Earth to create an airflow through a wind tunnel up-run, whereby to produce electrical power using wind-driven turbines; the output can be enhanced by the extra rising air heated by solar heat, or heat from other sources e.g. geothermal.

2. The construction of a shaft excavation 2 providing a open side 3 from one metre wide to 2,000 metres wide for tipping over or dumping of rubble down the mountain side, is very cost efficient. Covering the open side 3 with flexible cover 7, which permits wind to be deflected inwards and upwards towards the exit end of the wind tunnel, 8 is also beneficial.

3. The spreading of rubble from the excavation to form a heat sink (supplementd if necessary by industrial rubble), and the addition of a glass collector roof 5 at the base of the mountain close to the inlet of the wind tunnel 8, are also beneficial.

The excavation may be oval, semicircular, or other suitable shape, with a corresponding chimney section. Preferably the chimney sides are smooth, for non-turbulent air flow.

The wind turbines may be located adjacent the base of the wind tunnel, or at any location within the wind tunnel e.g.

part way up or adjacent the top, depending upon their design.

The construction is preferably carried out from the top downwards, however, other methods such as boring from the bottom upwards, or a combination of these methods, may also be utilised.

The cover 7 can be of various materials, both flexible and non-flexible. Additionally, it may be inflated; it may be insulated. It may be of various shapes and designs. It could also be a solid construction, e.g. a concrete or steel wall.

The wind tunnel may be constructed from one or more shafts or tubes bored into the ground rock, or by borings into softer rock(s) which are then strengthened by a solid material such as steel or a solidifying material such as concrete.

Advantages of the invention include that the chimney once constructed can largely concealed from distant viewing, and so may be more acceptable in scenic locations i.e. since much of the chimney is within the hill side only the cover will be seen, and need access for maintenance (of the flaps and/or engine).




 
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