GB2384528A

GB2384528A - wind-power device for buildings

Info

Publication number: GB2384528A
Application number: GB0126231A
Authority: GB
Inventors: Thomas John Mcneel Robertson
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-01
Filing date: 2001-11-01
Publication date: 2003-07-30
Anticipated expiration: 2021-11-01
Also published as: GB2384528B; GB0126231D0

Abstract

A wind power device for sloping or pitched roofs of buildings comprises an air turbine 20 mounted at the apex of the roof 15. Air inlets 12 are located around the base of the roof, with an outlet being situated past the turbine 20. In use, the air is guided towards the air inlets 12 by baffles 17, enters at the base of the pitched roof, and due to the internal shape of the roof, accelerates as it travels towards the turbine. Non-return valves 13 are mounted at the air inlets, to ensure that the incoming air can only exit through the turbine 20. To make use of the wind energy, the turbine is connected to a heat pump 27 or an electric generator.

Description

Improvements in or relating to Wind Power Devices for Buildings This invention relates to wind power devices and more particularly, but not exclusively to a wind power device with minimal visual impact as a source of domestic heat.

According to the present invention, a wind power device comprises, a duct having at least one declivous surface portion thereof arranged to be exposed to the wind, an inlet into the duct at or near the lower end of the declivous surface portion for air to flow into the duct and an outlet at or near the upper end of the duct and an air turbine positioned within the duct so as to be driven by the wind-generated airflow in the duct.

Preferably the inlet into the duct near or below the lower end of the declivous surface portion is positioned so as to augment the air flowing into the duct by the effect of wind impingement and the outlet at or near the upper end of the declivous surface is positioned so as to facilitate the flow of air from the duct due to the effect of localised reduction in air pressure caused by wind flow over the building.

In one preferred form of the invention, the declivous surface portion extends above the upper end of a baffle intended to be incident to the wind so as to direct air through the lower inlet into the duct.

Desirably, a said declivous surface portion having an outlet at or near the upper end thereof and a said inlet at or near the lower end thereof may be provided at each side round the duct so as to provide an omni-directional wind power device.

A fundamental problem with wind energy is the diffuse nature of the power available.

The collection area required for the production of a useful amount of power is achieved conventionally by the presentation of a large working surface (or swept areas) to the wind.

However it is also possible to use a large static structure as the collection area to

produce a local increase in the air velocity and thus achieve some concentration of the energy.

Since the power that can be extracted from an airstream is proportional to the cube of the wind velocity, the moving parts in such a system can be made much smaller than in a system of the same power output but without this local increase in air velocity. Systems that give a localised increase in air velocity have been investigated. The'Vortex Generator'put forward

by the Grumman Aircraft Corp is one example, while other proposals make use of stagnation

(TM) pressure effects.

However, for a useful scale of electricity production the large specialised static structures, together with their associated air turbines would probably cost more than the 'conventional'wind generators with their smaller structures but larger moving parts. This would be particularly so for offshore locations where the costs of transport of materials and erection are especially high. The cost disadvantage of these systems changes radically however if they can be incorporated into a structure which has to be built anyway (e. g. a house), since then only the cost of the small wind turbine and minor modifications to the main structure should be set against the energy generated. The invention therefore has one application for providing a source of heat or energy for a conventional house without being visually obtrusive.

The invention will now be further described by-way of example with reference to the accompanying drawing the single figure of which shows a perspective, partially cut away, view of a pitched-roof house.

Referring now to the Figure, a house 10 is shown generally of conventional form below its eaves 11 but at the eaves soffit 11 around the house (but shown on two sides only) a plurality of inlets 12 are provided each having a respective flap-type non-return valve 13 for the admittance of air into a duct in the form of a space 14 below a pitched-roof 15 having declivously extending sides 16, the eaves 11 also having triangular shaped baffles at each end of the respective inlets 12. The volume of the roof space shown in the Figure may be optimised by incorporating a second, inner, roof-shaped structure (not shown, ) to minimise pressure losses due to sudden changes in the airstream cross-section. An air turbine 20 is mounted on a vertical axis at the apex of the roof 15 and has a shroud 21 therearound, which defines an inlet 22 to the turbine. If desired, an additional flap-type valve 23 may be positioned at each side 16 of the roof 15 to provide additional means of modifying air flow to

the turbine as an added means of controlling its speed. A heat pump 27 situated below the air turbine 20 is drivably connected to the turbine 20 by a drive shaft 28.

In operation, with wind impinging on the house 10 in the direction of arrow'A', a pressure is generated on the upwind side of the house 10 below the eaves 11 and a suction is generated on the corresponding downwind side and above the roof 15 of the house 10. Windblown air, guided by baffles 17, flows through the inlets 12 on the upwind side of the house 10 into the space 14 but is prevented from flowing out of the inlets 12 on the downwind side of the house by the respective non-return valves 13 there, and thus flows through the space 14 at an enhanced velocity (assisted by the shape of space 14) to the air turbine 20. Rotation of the turbine 20 turns the drive shaft 28 and causes a corresponding rotation of the heat pump, which therefore produces a heat output from the wind impinging on house 10.

The rotational speed of the turbine may, if desired, be controlled by incorporating means (not shown) of restricting the opening of the non-return valves 13 so as to enable the turbine 20 to operate within its designed parameters in high wind conditions.

One advantage of the invention for domestic uses is that in Northern Europe wind velocities tend to be higher in the winter when there is the greatest demand for heating occurs.

A well-insulated average size of house 10 requires between 3-4 kW of continuous heating.

Assuming, for example 3. 5kW and a modest coefficient of performance or 2.5 for the heat pump 27, the air turbine 20 would be required to deliver about 1. 4kW for heating selfsufficiency. If the winter windspeed is assumed to be 10metres/sec on average (based on United Kingdom data), an air turbine 20 of about 1.75 metres diameter would be adequate for the house-heating demand and for providing some reserve capacity for a certain amount of heat storage during the periods when the wind is at or above the average speed. The appearance of a house 10 surmounted by a shroud 21 for such an air turbine 20 should reasonably conform to a generally accepted building appearance Although the invention has been described in relation to its use in a domestic building as a source of domestic heat, it will be understood that the invention may be used for similar purposes in buildings or structures used for other purposes, or for alternative applications, such as the generation of electric power.

Claims

CLAIMS 1 A wind power device integrated into the structure of a building.

2 A wind power device as claimed in Claim 1 with minimal visual obtrusiveness.

3 A wind power device as claimed in Claim 1 or Claim 2 that is positioned to utilise the localised airflow velocity enhancement effect of declivious surfaces.

4 A wind power device as claimed in Claim 1 or Claim 2 or Claim 3 that is positioned to utilise the localised airflow velocity enhancement effect caused by wind impinging on vertical surfaces.

5 A wind power device as claimed in Claim 1 or Claim 2 in which the structural layout of the building provides effective means of directing the locally enhanced air flows of Claim 3 and Claim 4 towards the turbine of the wind power device.

6 A wind power device as claimed in Claim 1 or Claim 2 which provides means of confining the directed flow of air of Claim 5 by providing means of preventing this air from by-passing the turbine by venting to the downwind side of the building.

7 A wind power device as claimed in Claim 1, Claim 2, Claim 3 Claim 4 Claim 5 or Claim 6 that utilises the energy of an air stream impinging on the building regardless of the direction of the wind.

8 A wind power device as claimed in Claim 1 Claim 2 or Claim 7 that provides means of speed control by limiting the airflow to the turbine during periods of high wind speed..

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Amendments to the claims have been filed as follows CLAIMS 1 A wind power apparatus, for use in a building, where said apparatus comprises: a roof member, contiguous with and extending horizontally beyond the tops of the walls of said building, said roof member having a lower surface, a declivous upper surface having an apex, and an air turbine within said apex; where said air turbine is driveable by air, introduced into said roof member from below to pass through said roof member and through said air turbine ; where said lower surface of said roof member comprises a plurality of openings, external to said walls; and where each of said plurality of openings is operative to receive, as air, stagnated wind, from the wall of the building immediately there-below, into said roof member to drive said air turbine.
2 An apparatus, according to claim 1, wherein each of said plurality of openings comprises a non-return valve, autonomously operative, under the action of differential air pressure, to allow air to enter said roof member through said opening and operative to prevent air leaving said roof member through said opening.
3 An apparatus, according to claim 2, wherein said air turbine receives driving air irrespective of the direction of arrival of wind at the building.
4 An apparatus, according to claim 2 or claim 3, wherein the extent of opening of said non-return valve is selectable to control the rate of rotation of said air turbine.
5 An apparatus, according to claim 1, 2,3 or 4, wherein said apex comprises a flap valve, operable to vent, to the atmosphere, a selectable portion of the air otherwise destined to pass through said air turbine.
6 An apparatus, according to any one of the preceding claims, wherein said building comprises walls around 360 degrees in the horizontal direction.

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7 An apparatus, according to any one of the preceding claims, wherein said roof member comprises the roof of a pitch-roofed house.
8 An apparatus, according to claim 7, wherein said plurality of openings are provided beneath the eaves of the roof member at the eaves soffit of the pitch roofed house.
9 An apparatus, according to claim 7 or claim 8, wherein said roof member comprises an inner, roof-shaped member to define the path of air within said roof member.
10 An apparatus, according to any one of the preceding claims, wherein said air turbine is coupled to drive a heat pump.
11 An apparatus, according to any one of the preceding claims, wherein said air turbine is coupled to drive an electrical generator.