GB2500678A

GB2500678A - Heatsinks for thermoelectric generators

Info

Publication number: GB2500678A
Application number: GB1205603.2A
Authority: GB
Inventors: Neil Lee Squires; Stephen Means
Original assignee: Spirax Sarco Ltd
Current assignee: Spirax Sarco Ltd
Priority date: 2012-03-29
Filing date: 2012-03-29
Publication date: 2013-10-02
Anticipated expiration: 2032-03-29
Also published as: GB201205603D0; GB2500678B

Abstract

A heatsink 10 comprises a heatsink base 9 arranged to be thermally and fixedly coupled to a component and a heatsink head 16 comprising a plurality of spaced heatsink plates 18 and coupled to the heatsink base by a standoff 12, wherein the heatsink head can be fixed in one of a plurality of angular positions with respect to the heatsink base and the heatsink base and standoff are configured to conduct heat away from the component to the heatsink head. The heatsink preferably comprises a locking arrangement having engaged and disengaged configurations. Also disclosed is a thermoelectric power source 2 comprising a base member 6, the heatsink of the invention and a thermoelectric generator device (8, figure 5). Further disclosed is an apparatus for measuring flow in a fluid duct comprising said thermoelectric power source, wherein the base member is coupled to the outer surface of the fluid duct, and a flow meter arranged to measure the flow and powered by the thermoelectric power source.

Description

tM:;: INTELLECTUAL .*.. PROPERTY OFFICE Application No. 0B1205603.2 RTM Date:29 August 2012 The following terms are registered trademarks and should be read as such wherever they occur in this document: European Thermodynamics Limited Intellectual Properly Office is an operaling name of Ihe Patent Office www.ipo.gov.uk

A HEATSINK

The invention relates to a heatsink, and particularly, but not exclusively, to heatsink for a thermoelectric generator.

In order to control most industrial processes involving steam it is necessary to monitor the flow of the steam. This is achieved by using a flow meter. Our co-pending application GB2483369 describes a mass flow meter which advantageously utilises the energy of the steam itself to power the flow rate meter. To achieve this, the flow meter uses a thermoelectric generator which is mounted to a conduit or steam line in which the steam flows. Thermoelectric generators convert heat (i.e. a temperature differential) into electrical energy using the Seebeck or thermoelectric effect.

Accordingly, the heat of the steam generates electrical energy which can be used to power the electronics of the flow rate meter.

As described above, the thermoelectric generator is thermally coupled to the steam line. To maintain the required temperature differential, an opposing side of the thermoelectric generator is held in contact with an upper conductive member which is part of, or is thermally coupled to, a heatsink. The heatsink is exposed to the temperature of the ambient air and dissipates heat through convection. The voltage produced by the thermoelectric generator is proportional to the temperature differential and therefore its efficiency is heavily reliant on the effectiveness of the heatsink.

The flow meter of GB2483369 utilises a heatsink comprising a standoff which conducts heat away from the thermoelectric generator. The standoff is coupled at its distal end to a head which comprises a plurality of horizontally stacked and spaced discs or plates. The plates increase the surface area of the heatsink to improve convection of heat to the ambient air. However, the horizontal orientation of the plates allows ambient air to flow between adjacent plates in the horizontal plane only.

In order to increase the flow of ambient air across the heat exchanger plates it is desirable to re-orientate the plates in a vertical direction. With this arrangement, ambient air is allowed to flow between adjacent plates in both the horizontal and vertical planes.

However, with a vertical arrangement of plates it is imperative that the plates are orientated in the direction of airflow (i.e. towards a window or other ventilation source), otherwise the plates will block the airflow and prevent cooling.

Typically, the head would be attached to the standoff using complementary screw threads. This provides excellent thermal coupling between the head and the heat pipe.

Nevertheless, with such a coupling the orientation of the head and plates is determined by the position in which the threads bottom out. Whilst a set or grub screw may be used to lock the relative positions of the head and standoff prior to the threads bottoming out, this reduces the contact area between the two components and thus is detrimental to thermal coupling.

It is therefore desirable to be able to position the head in any orientation without adversely affecting thermal coupling.

According to an aspect of the invention there is provided a heatsink, comprising: a heatsink base arranged to be thermally and fixedly coupled to a component; and a heatsink head comprising a plurality of spaced heatsink plates and which is coupled to the heatsink base by a standoff, wherein the heatsink head can be fixed in one of a plurality of angular positions with respect to the heatsink base; and wherein the heatsink base and standoff are configured to conduct heat away from the component to the heatsink head which is configured to transfer heat to the surrounding air.

The heatsink head may be rotatable relative to the standoff. Alternatively, the heatsink head and standoff may be rotatable relative to the heatsink base.

The heatsink head may be fixed in an angular position which substantially aligns the plurality of heatsink plates with a direction of airflow (for example, originating from a window or ventilation source) or other fluid flow.

The plurality of angular positions may be discrete positions. The discrete positions may be defined by a number of cooperating indexing features provided between the heatsink head and heatsink base. For example, the heatsink head and heatsink base may be coupled by portions having rotational symmetry (i.e. regular polygons), or splines, ridges, teeth or other keying features.

The standoff may extend from the heatsink base in an axial direction.

The heatsink head may be fixed in one of a plurality of angular positions with respect to the axial direction.

The plurality of heatsink plates may be orientated in a plane having at least a component in the axial direction.

The plurality of heatsink plates may be orientated in an axially extending plane.

In use, the longitudinal axis of the standoff may be orientated substantially in the vertical direction. The plurality of heatsink plates may then also be orientated in the vertical direction. However, the coupling of the component to, for example, a steam line may be such that the plurality of heatsink plates are maintained in the vertical orientation even if the standoff is not (or cannot be) orientated in the vertical direction.

In other words, the coupling may allow the standoff to rotate in the plane of the plurality of heatsink plates.

The standoff may be fixed with respect to the heatsink base and the heatsink head may be fixed in one of a plurality of angular positions with respect to the standoff.

The heatsink may further comprise a locking arrangement having an engaged configuration in which the heatsink head is fixed in the selected angular position and a disengaged configuration in which the heatsink head can be moved between the plurality of angular positions.

In the disengaged configuration the heatsink head may rotate without any translation in the axial direction.

The locking arrangement may comprise corresponding male and female locking portions.

The heatsink head or standoff may comprise the male locking portion and the other of the heatsink head and standoff may comprise the female locking portion. In particular, the heatsink head may comprise the female locking portion and the standoff may comprise the male locking portion.

The heatsink head and standoff may be coupled together by the male and female locking portions.

The male and female locking portions may be tapered.

The male and female locking portions may form a locking taper, such as a Morse taper.

Alternatively, the heatsink head and standoff may adjoin via planar abutting surfaces.

The locking arrangement may further comprise a lead screw extending between the heatsink head and the standoff. The lead screw may extend between the heatsink head and the standoff in the axial direction.

The lead screw may be arranged such that rotation of the lead screw causes engagement and disengagement of the locking arrangement.

Rotation of the lead screw may result in relative movement between the male and female locking portions.

Rotation of the lead screw in a first direction may cause the male and female locking portions to be drawn towards one another so as to engage the locking arrangement.

Conversely, rotation of the lead screw in a second direction may cause the male and female locking portions to be forced away from one another so as to disengage the locking arrangement.

For example, where tapered male and female portions are used, rotation of the lead screw may allow a locking taper to be connected and disconnected. Alternatively, where the heatsink head and standoff comprise planar abutting surfaces, the rotation of the lead screw may force the surfaces to engage one another and may space the surfaces apart so as to allow the heatsink head and standoff to freely rotate.

A screw head of the lead screw may be disposed at the heatsink head and a thread of the lead screw may engage a corresponding thread disposed in the standoff, or vice versa.

The heatsink may further comprise a retaining member which limits axial movement but permits rotational movement of the screw head relative to the heatsink head. The retaining member may prevent axial movement so that rotation of the lead screw in the second direction forces the heatsink head and standoff apart.

The retaining member may comprise a washer and/or circlip. Such an arrangement may allow access to the head of the lead screw, whilst preventing axial movement.

According to another aspect of the invention there is provided a thermoelectric power soulce, comprising: a base member arranged to be thermally coupled to a source of thermal energy; a heatsink as described above; and a thermoelectric generator device disposed between the base member and the heatsink base and configured to generate power from a temperature differential between the base member and the heatsink base.

The lower surface of the base member may have a concave profile that is arranged to engage with the outer surface of a steam line.

The thermoelectric power source may further comprise an attachment mechanism for attaching the thermoelectric power source to a steam line, such as a U-bolt. The attachment mechanism may be configured such that the plurality of heatsink plates are maintained in a vertical orientation even if the standoff is not (or cannot be) orientated in the vertical direction. In other words, the attachment mechanism may allow the standoff to rotate in the plane of the plurality of heatsink plates.

According to another aspect of the invention there is provided an apparatus for measuring flow in a fluid duct, comprising: a thermoelectric power source as described above, wherein the base member is coupled to the outer surface of the fluid duct such that the thermoelectric generator device generates power from the temperature of the fluid within the fluid duct; and a flow meter arranged to measure the flow within the fluid duct; wherein the thermoelectric power source supplies power to the flow meter.

The invention may comprise any combination of the features and/or limitations referred to herein, except combinations of such features as are mutually exclusive.

For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-Figure 1 is a perspective view of a thermoelectric power source comprising a heatsink in accordance with an embodiment of the invention; Figure 2 is a front view of the thermoelectric powei souice of Figuie 1; Figure 3 is a side view of the thermoelectric power source; Figure 4 is a top view of the thermoelectric power source; Figure 5 is a side cross-sectional view of the thermoelectric powei soulce; and Figure 6 is an enlarged view of a portion of Figure 5 showing the heatsink in detail.

Refeiiing to Figures 1 to 4, there is shown a theimoelectric power source 2 foi generating electrical eneigy from a heat soulce, such as a steam line (not shown). The thermoelectric power source 2 comprises a U-bolt 4 which allows the thermoelectric power source 2 to be held tightly against an outer surface of the steam line and thus to thermally couple the thermoelectiic powei source 2 to the steam line.

The thermoelectric power source 2 comprises a solid base member 6, an array of thermoelectric generator devices 8 (see Figure 5), and a heatsink 10 in accordance with an embodiment of the invention. The base membei 6 is made from aluminium and has a concave lower surface, the profile of which corresponds to the outer profile of the steam line. In use, the concave surface of the base member 6 engages and is held tightly against the outer suiface of the steam line by the U-bolt 4. A thermally conductive paste may be placed between the steam line and the base member 6 at the time of assembly to enhance heat transfer therebetween.

The ariay of thermoelectric genelator devices 8 is capable of genelating power from a temperature differential using the Seebeck effect. For example, the array of thermoelectric devices 8 may be a 40 x 40mm thermoelectric generator model number GM-127-14-16-S available from European Thermodynamics Ltd. However, it should be appreciated that other thermoelectric devices could also be used, for example the high-temperature models from TE Technology Inc. One side of the array 8 is in contact with the base member 6 and is therefore exposed to the heat from the steam in the steam line, and the other side of the array 8 is in contact with a base 9 which is part of the heatsink 10. The heatsink 10 is exposed to the temperature of the ambient air and thus conducts heat away from the array 8.

The output of the thermoelectric power source 2 may be coupled to a flow meter (not shown), such as a mass flow meter, via power cable 14. The flow meter may be used to measure the mass flow rate of steam through the steam line. The flow meter and associated control electronics may form pad of a first discrete unit and the thermoelectric power source 2 may form pad of a second discrete unit that supplies power to the first discrete unit via the power cable 14. Specific details of the construction and operation of the flow meter are outside of the scope of this application and thus are omitted for clarity. In any case, the thermoelectric power source 2 may be used to power various alternative appliances depending on the desired purpose.

It is noted that the power produced by the thermoelectric power source 2 may be stored in a temporary power source, such as a re-chargeable battery, prior to being used. The temporary power source may be any device that can retain a charge. For example, capacitors or super-capacitors may be used. Alternatively, the appliance may be directly powered by the thermoelectric power source 2.

The heatsink 10 comprises a standoff 12 which is coupled to the heatsink base 9. A distal end of the standoff 12 is coupled to a heatsink head 16. The heatsink head 16 comprises a plurality of vertically stacked and spaced discs 18 (plates) which increase the surface area of the heatsink head 16. A longitudinal axis of the standoff 12 defines an axial direction and the discs 18 are preferably orientated in this direction.

As better shown in Figures 5 and 6, the heatsink head 16 comprises a central opening (female locking portion) orientated in the axial direction, which receives a portion (male locking portion) of the standoff 12. Both the opening of the heatsink head 16 and the portion of the standoff 12 are provided with a Morse taper to form a self-locking taper connection (locking arrangement) between the heatsink head 16 and the standoff 12.

A screw 20 (lead screw) passes from the heatsink head 16 into the standoff 12. An outer surface of the heatsink head 16 is provided with a recess 22 which receives a head 24 of the screw 20. A shank 26 of the screw 20 passes through an opening 28 at a base of the recess and extends into the central opening of the heatsink head 16. The standoff 12 is provided with a threaded bore 30 which receives a complementary thread provided on the shank 26 of the screw 20.

The head 24 of the screw 20 is retained in the recess 22 of the heatsink head 16 by a washer 32 and a circlip 34. The circlip 34 has a fixed position in the recess 22 and thus limits the axial movement of the washer 34 and screw 20, but permits rotational movement of the screw head 24 relative to the heatsink head 16.

Accordingly, rotation of the screw 20 in a first direction causes the portion of the standoff 12 to be drawn further into the central opening of the heatsink head 16. This action forms the self-locking taper connection and thus fixedly couples the heatsink head 16 to the standoff 12. In this engaged configuration, relative rotation between the heatsink head 16 and the standoff 12 is prevented so that the heatsink head 16 maintains a fixed angular position relative to the standoff 12 with respect to the axial direction.

Conversely, rotation of the screw 20 in a second (counter) direction causes the portion of the standoff 12 to be forced out of the central opening of the heatsink head 16. This action breaks the self-locking taper connection and thus decouples the heatsink head 16 and the standoff 12. In this disengaged configuration, the heatsink head 16 is allowed to rotate freely relative to the standoff 12, thus changing the angular position of the heatsink head 16 relative to the standoff 12 with respect to the axial direction.

In the disengaged configuration, the heatsink head 16 may rotate fully (i.e. through an entire 360 degree revolution) about the standoff 12.

In use, the thermoelectric power source 2 is connected to the steam line using the U-bolt 4. Accordingly, the thermoelectric power source 2 is aligned (about the axial direction) with a longitudinal axis of the steam line. Nevertheless, the thermoelectric power source 2 may be positioned in any radial direction about the steam line.

Preferably, the longitudinal axis of the standoff 12 is orientated substantially in the vertical direction, such that the discs 18 are also orientated in the vertical direction.

However, the orientation of the U-bolt 4 allows the discs 18 to be maintained in the vertical orientation even if the standoff 12 is not (or cannot be) orientated in the vertical direction. In other words, the U-bolt 4 allows the standoff 12 to rotate in the plane of the discs 18 (i.e. the discs 18 lie in the plane of rotation about the steam line).

It is desirable to maximise the temperature drop across the thermoelectric device array 8 in order to maximise the amount of power that the thermoelectric power source 2 generates. This may be achieved by maximising the efficiency of the heat sink 10.

Accordingly, during installation of the thermoelectric power source 2, the screw 20 is unscrewed so that the heatsink head 16 and standoff 12 are in the disengaged configuration where the heatsink head 16 is allowed to rotate freely relative to the standoff 12.

The heatsink head 16 may be rotated so that the plurality of discs 18 are aligned with a direction of airflow. For example, the airflow may be provided by a window or other ventilation source. With such an alignment, the airflow can pass between adjacent discs 18 without any impediment.

Once the heatsink head 16 and discs 18 are orientated in the desired direction, the screw 20 is screwed in so as to draw the portion of the standoff 12 into the central opening of the heatsink head 16, thus forming the self-locking taper connection.

Consequently, the heatsink head 16 is locked in position to maintain the angular position of the heatsink head 16 relative to the standoff 12.

If the operating conditions of the thermoelectric power source 2 vary over time such that the direction of airflow changes, the self-locking taper connection may be broken by unscrewing the screw 20 to force the heatsink head 16 away from the standoff 12.

The heatsink head 16 may then be reorientated into the desired direction, before reforming the self-locking taper connection.

Although not shown, the standoff 12 may comprise a heat pipe extending from one end of the standoff 12 to the other in order to improve heat transfer.

Further, whilst the discs 18 are shown as being circular, any form of plate may be used to increase the surface area of the heatsink head 16. In addition, the discs 18 do not necessarily have to be orientated in the axial direction. For example, the discs 18 may be orientated in a direction which has only a component in the axial direction.

The coupling between the heatsink head 16 and the standoff 12 is not limited to the arrangement described above. For example, the male and female portions may be reversed such that the heatsink head 16 comprises a stem or other protrusion which is received in an opening in the standoff 12.

Moreover, the heatsink head 16 and standoff 12 may be integrally formed or otherwise fixedly connected, with the orientation adjustment being provided at a coupling between the standoff 12 and the heatsink base 9.

The screw 20 may instead pass from the standoff 12 into the heatsink head 16 to achieve the same functionality.

In fact, the screw 20 may be omitted entirely and the self-locking taper connection formed by forcing the heatsink head 16 onto the standoff 12 (for example, by hammering) when in the desired angular position. With such an arrangement, the self-locking taper connection could be broken by forcing the heatsink head 16 away from the standoff 12 with sufficient force.

Alternatively, the screw 20 may be replaced by a tapered pin which is used to form a self-locking taper connection with a corresponding tapered opening in the standoff 12 (or heatsink head 16).

Furthermore, the male and female portions of the heatsink head 16 and standoff 12 need not have a tapered cross-section. Instead, the male and female portions may have a uniform cross-section along their length. Nevertheless, the tapered arrangement increases surface contact and thus improves thermal coupling.

Moreover, the heatsink head 16 and standoff 12 need not have male and female portions. Instead, the heatsink head 16 and standoff 12 may comprise planar surfaces which abut one another. With this arrangement, the screw 20 forces the abutting surfaces together, and the friction between the surfaces prevents relative rotation of the heatsink head 16 and standoff 12. However, again, the tapered arrangement increases surface contact and thus improves thermal coupling.

The coupling between the heatsink head 16 and standoff 12 may provide a plurality of discrete angular positions. For example, the heatsink head 16 and standoff 12 may comprise cooperating indexing features which interlock in a number of predefined positions. For example, the neck and head members may be coupled by portions having rotational symmetry (i.e. regular polygons), or splines, ridges, teeth or other keying features.

Claims

CLAIMS: 1. A heatsink comprising: a heatsink base arranged to be thermally and fixedly coupled to a component; and a heatsink head comprising a plurality of spaced heatsink plates and which is coupled to the heatsink base by a standoff, wherein the heatsink head can be fixed in one of a plurality of angular positions with respect to the heatsink base; and wherein the heatsink base and standoff are configured to conduct heat away from the component to the heatsink head which is configured to transfer heat to the surrounding air.
2. A heatsink as claimed in claim 1, wherein the standoff extends from the heatsink base in an axial direction.
3. A heatsink as claimed in claim 2, wherein the heatsink head can be fixed in one of a plurality of angular positions with respect to the axial direction.
4. A heatsink as claimed in claim 2 or 3, wherein the plurality of heatsink plates are orientated in a plane having at least a component in the axial direction.
5. A heatsink as claimed in any of claims 2 to 4, wherein the plurality of heatsink plates are orientated in an axially extending plane.
6. A heatsink as claimed in any preceding claim, wherein the standoff is fixed with respect to the heatsink base and wherein the heatsink head can be fixed in one of a plurality of angular positions with respect to the standoff.
7. A heatsink as claimed in any preceding claim, further comprising a locking arrangement having an engaged configuration in which the heatsink head is fixed in the selected angular position and a disengaged configuration in which the heatsink head can be moved between the plurality of angular positions.
8. A heatsink as claimed in claim 7, wherein the locking arrangement comprises corresponding male and female locking portions.
9. A heatsink as claimed in claim 8, wherein the heatsink head or standoff comprises the male locking portion and the other of the heatsink head and standoff comprises the female locking portion.
10. A heatsink as claimed in claim 9, wherein the heatsink head and standoff are coupled together by the male and female locking portions.
11. A heatsink as claimed in any of claims 8 to 10, wherein the male and female locking portions are tapered.
12. A heatsink as claimed in claim 11, wherein the male and female locking portions form a locking taper.
13. A heatsink as claimed in any of claims 7to 12, wherein the locking arrangement further comprises a lead screw extending between the heatsink head and the standoff.
14. A heatsink as claimed in claim 13, wherein the lead screw is arranged such that rotation of the lead screw causes engagement and disengagement of the locking arrangement.
15. A heatsink as claimed in claim 14 when appended to claim 8, wherein rotation of the lead screw results in relative movement between the male and female locking portions.
16. A heatsink as claimed in claim 15, wherein rotation of the lead screw in a first direction causes the male and female locking portions to be drawn towards one another so as to engage the locking arrangement.
17. A heatsink as claimed in claim 15 or 16, wherein rotation of the lead screw in a second direction causes the male and female locking portions to be forced away from one another so as to disengage the locking arrangement.
18. A heatsink as claimed in any of claims 13 to 17, wherein a screw head of the lead screw is disposed at the heatsink head and a thread of the lead screw engages a corresponding thread disposed in the standoff.
19. A heatsink as claimed in claim 18, further comprising a retaining member which limits axial movement but permits rotational movement of the screw head relative to the heatsink head.
20. A heatsink as claimed in claim 19, wherein the retaining member comprises a washer and/or circlip.
21. A thermoelectric power source, comprising: a base member arranged to be thermally coupled to a source of thermal energy; a heatsink in accordance with any preceding claim; and a thermoelectric generator device disposed between the base member and the heatsink base and configured to generate power from a temperature differential between the base member and the heatsink base.
22. A thermoelectric power source according to claim 21, wherein the lower surface of the base member has a concave profile that is arranged to engage with the outer surface of a steam line.
23. A thermoelectric power source according to claim 21 or 22, further comprising an attachment mechanism for attaching the thermoelectric power source to a steam line.
24. An apparatus for measuring flow in a fluid duct, comprising: a thermoelectric power source as claimed in any of claims 21 to 23, wherein the base member is coupled to the outer surface of the fluid duct such that the thermoelectric generator device generates power from the temperature of the fluid within the fluid duct; and a flow meter arranged to measure the flow within the fluid duct; wherein the thermoelectric power source supplies power to the flow meter.
25. A heatsink, thermoelectric power source or apparatus for measuring flow substantially as described herein with reference to the accompanying drawings.