WO2007121504A1

WO2007121504A1 - Improvements to thermoelectric generator

Info

Publication number: WO2007121504A1
Application number: PCT/AU2007/000374
Authority: WO
Inventors: Jason Andrew Hopkins
Original assignee: Jason Andrew Hopkins
Priority date: 2006-04-24
Filing date: 2007-03-27
Publication date: 2007-11-01
Also published as: EP2054950A1; CN101485005A; BRPI0711490A2

Abstract

This invention is used to convert heat in to electricity with high conversion efficiency. It uses the an improved structure of thermocouple to perform this task. The improvement revolves around the use of parallel, very fine wires of similar material all connected parallel to each other and only electrically connected at the ends. The invention could be used for the efficient conversion of heat from solar energy to electricity or heat from biofuel combustion, fossil fuel combustion, nuclear fission or fusion etc, to electricity.

Description

Improvements to Thermoelectric Generators

This invetnion relates to thermoelectric generators. More particularly, although not exclusively, it discloses an improved generator of the type comprising a plurality of thermocouples arranged aerosar a temperature differential

Prior art thermoelectric generators as typified by US patent 4.363.926 comprise a plurality of thermocouples, each formed by two conductor atripe of different metals (e.g. copper and conatantan) arranged in pairs and printed onto a substrate strip. The thermocouples extend across a temperature differential and are connected in series to produce an electrical potential. As each thermocouple comprises only two conductors the energy conversion efficiency is relatively low. The presence of the substrate stripe is a further source of energy loss.

It is therefore an object of this invention to ameliorate the aforementioned disadvantage and accordingly a thermoelectric generator is disclosed for operation across a temperature differential, said generator including thermocouples formed by conductors of two different metals arranged in pairs and extending between coupled at spaced apart locations which in use of said generator define said temperature differential wherein at least some of said conductors are constituted by a plurality of discrete segments of filament connected in parallel

Preferably but not essentially said filaments may comprise (5 urn diameter wires.

It is further preferred that each of said conductors comprise about 500 of said wires.

It is further preferred that said wires are about 80 cm in length.

It is further preferred that said two different metals are nickel and iron.

In another aspect this invention also discloses a method of forming one of said conductors, the method including the following steps: -

- winding a length of said filament around a form having a circumference equal to the length of said conductor to form coils equal to the number of segments of filament required for said conductor,

- bonding across said coils at a point on said circumference with a conducting material, and

- cutting the coils at said point to produce said plurality of discrete segments connected in parallel-

Preferably but not essentially said form is cylindrical in shape .

It is further preferred that said conducting material is solder.

It is further preferred that the length of filament is wound onto said cylinder in a guided manner whereby the coils are disposed side-by-side .

One currently preferred embodiment of the invention will now be described with reference to the attached representations in which; -

figure 1 is a schematic view of a thermocouple according to said invention, figure 2 is a schematic view of a conductor for the thermocouple of figure 1, figure 3 is a schematic cross-sectional view of the packing arrangement for the conductor, and figures 4 and 5 are schematic views of the preferred apparatus for forming the conductor of figure 2.

Referring first to figures I and 2 there is a thermoelectric generator which comprises a plurality of thermocouples each formed by pairs of iron and nickel conductors 2a and 2b, The conductors are arranged in series and extend between couples 2c, 2d at hot and cold sites respectively. In asccordance with this invention each conductor is comprised of 500 wire filaments each 80 cm long and 65um in diameter. The wire filaments 3, 4 as shown in figure 2 are connected in parallel by bonding at each end 5 to form said conductors. It has been found through trials conducted by the inventor that this multiple filament arrangement for the conductors provides a substantial improvement in operating efficiency over the single metal strip configuration of prior art devices. With said prior art devices efficiencies are limited to about 4%. By contrast the inventor envisages efficiencies of up to about 80% using the described multiple filament conductors.

As shown in figure 3 the arrangement of alternating iron and nickel multifilament conductors 6 when incorporated into a thermoelectric generator according to this invention are preferably packed into the smallest volume with insulating material 7 on four sides parallel to the couples. The junction 8 at one end of the conductors is heated and the opposite end is cooled to create the required temperature differential. The surface areas of the conductors themselves are not heated or cooled and preferably are thermally insulated by the material 7.

Figures 4 and 5 illustrate the currently preferred apparatus and method of forming the conductors. A. continuous length of filament wire 9 is wound from a supply spool 10 onto a cylinder 11 having a circumference equal to the conductor length. When the number of side-by-side wound coils 12 on the cylinder corresponds to the required number of connector filaments said coils are bonded across their width at one point 13 with solder or other suitable conducting material. Subsequent cutting of the coils along line 14 produces a finished multi-strand conductor for use in a thermoelectric generator according to this invention.

It will thus be appreciated that this invention at least in the form of the embodiment disclosed provides a novel and improved form of thermoelectric generator. Clearly however the example described is only the currently preferred form of the invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the number, diameter and length of the conductor filaments aa well as the metals used for them made may all be changed according to design requirements or following further development work by the inventor.

Claims

1. A thermoelectric generator comprising a first conductor element in series with a second conductor element, the first conductor element being made of a first electrical conductor material and the second element being made from a second electrically conductive material that is different from to the first electrical conductor element material, wherein each conductive element is formed as a multifilament array of parallel electrical conductors joined at their ends.

2. A thermoelectric generator comprising a plurality of thermoelectric generators of claim 1 connected in series such that contact is only made between different electrically conductive materials.

3. A thermoelectric generator comprising a plurality of thermoelectric generators of claim 1 connected in parallel such that contact is only made between similar electrically conductive materials,

4. A thermoelectric generator comprising a plurality of thermoelectric generators of claim 2 connected in parallel such that contact is only made between similar electrically conductive material to achieve the desired electrical potential and current characteristics.

5. A method for forming multi-filament array of claim 1 a. Winding a strand of a chosen conductor onto a shaped object of uniform circumference for at least two revolutions b. Bonding the conductor material in one region c. Cutting though the bonded region too create 2 ends , with a parallel arrangement of conductor filaments extended between the ends so that the filaments are connected to each other at both ends of those ends

6. The method of claim 5 where in the said bonding material is electrically conductive.

7. A thermoelectric generator substantially as herein described with reference to the figures 1 to 5.