GB2593584A

GB2593584A - Heat exchange assembly and element for use therein

Info

Publication number: GB2593584A
Application number: GB2101189.5A
Authority: GB
Inventors: John Henry Nicholas
Original assignee: Sst Tech Ltd
Current assignee: Sst Tech Ltd
Priority date: 2020-01-29
Filing date: 2021-01-28
Publication date: 2021-09-29
Also published as: GB202101189D0; GB202001229D0

Abstract

A heat exchange element 20 comprising a body 20a including a heat transfer section defining at least one convoluted flow path 22a through the heat transfer section. The heat transfer section is integrally formed with a solid base section 24. Preferably, the body is manufactured using additive manufacturing, 3D printing techniques, laser sintering or power bed techniques. Preferably the heat transfer section has the appearance of an open cell foam defining at least one convoluted flow path through the body. Preferably, the flow paths define a periodic minimal surface. A second aspect relates to a heat exchange assembly comprising a housing (12, Fig 1) with a base (14, Fig 1) and the abovementioned heat exchange element 20 located within the housing and secured such that the base section 24 of the element is in thermal contact with the base 14 of the housing. A third aspect relates to a method of manufacturing the heat exchange element using an additive manufacturing process.

Description

HEAT EXCHANGE ASSEMBLY AND ELEMENT FOR USE THEREIN

This invention relates to a heat exchange element intended to form part of a heat exchange assembly, for example for cooling or heating of a device, and to an assembly incorporating such an element.

There are a number of applications in which there is a need to cool a device. By way of example, where a piece of equipment includes coils forming superconducting magnets, there is a need to cool the coils. One way of achieving this is by using a heat exchange assembly through which a cold gas or liquid passes, in use, the heat exchange assembly, or a part thereof, being in thermal contact with part of the device to be cooled.

In one known heat exchange assembly, a housing is provided, the housing having a base to be secured to the device to be cooled. The housing has an inlet and an outlet through which a cold fluid can be introduced into and exit from the housing. Located within the housing is a heat exchange element in the form of an open cell foam element of a metallic material such as copper. The heat exchange element is firmly secured to the base so as to be in thermal contact therewith. This may be achieved by heating the base of the housing or a similar copper mass known as a tinning iron, and applying solder to cover the surface of the base or the iron, ensuring that the solder is molten, and locating the heat exchange element upon the inner surface of the base such that the end part of the heat exchange element closest to the based becomes tinned or coated with solder. The heat exchange element may be removed at this point to allow checking to ensure that the tinning or coating is adequate. The heat exchange element is then returned into position to reheat the solder and, after cooling, is firmly secured in position, providing good thermal contact between the heat exchange element and the base. The heat exchange element may be of multipart form, if desired.

Whilst a heat exchange assembly fabricated using the technique described hereinbefore functions well, there is a desire to improve the manufacturing process to enable more efficiency in the manufacture thereof, and to enhance the cooling efficiency of the assembly. By way of example, the thermal contact between the heat exchange element and the base may not be perfect, negatively impacting upon the operating efficiency of the assembly.

It is an object of the invention to provide a heat exchange element and associated assembly in which at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

According to a first aspect of the invention there is provided a heat exchange element comprising a body including a heat transfer section defining at least one convoluted flow path through the heat transfer section, the heat transfer section being integrally formed with a solid base section.

It will be appreciated that by integrally forming the heat transfer section with the base section, good thermal transfer therebetween is ensured. By forming the base section to be of solid form, good thermal contact may be achieved in a relatively straightforward manner between the base section of the heat exchange element and, for example, a base of a housing within which the heat exchange element is located, in use, and the soldering process to secure the heat exchange element in position may be simplified.

The body is preferably manufactured using an additive manufacturing or 3D printing technique.

By way of example a laser sintering, powder bed approach may be taken. However, other additive manufacturing or 3D printing techniques may be used.

The heat transfer section may be of a form having the appearance of an open cell foam defining at least one the convoluted flow path through the body. However, this need not be the case and the convoluted flow path may be defined by a regularly arranged series of individual flow paths through the body. The individual flow paths may interconnect, preferably repeatedly, with one another within the body, if desired.

The shape or geometry of the convoluted flow path may be such as to define periodic minimal surfaces, such an arrangement being advantageous in that the surface area of the flow path may be optimised, and hence the heat exchange characteristics of the heat exchange element may be optimised, for a given rate of fluid flow through the heat exchange element. The shape or geometry of the flow path may be selected so as to promote turbulence within the fluid flowing within the flow path and/or to control the fluid flow rate.

The base section preferably has a thickness of at least 0.5mm, and is preferably in the range of 1-2mm. However, it will be appreciated that the invention is not restricted in this regard and the thickness may be selected depending upon the desired thermal and/or structural properties.

It is preferably of smooth flat form.

The body is preferably of a material of high thermal conductivity. Preferably, it is of a metallic material such as copper.

The invention also relates to a heat exchange assembly comprising a housing having a base, and a heat exchange element of the type described hereinbefore located within the housing and secured in such a manner that the base section thereof is in thermal contact with the base. The base section may be soldered to the base.

The invention also relates to a method of manufacture of a heat exchange element of the type described hereinbefore comprising the steps of using an additive manufacturing process to integrally form a heat transfer section, defining at least one convoluted flow path through the heat transfer section, with a solid base section.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view illustrating a heat exchange assembly in accordance with an embodiment of the invention; Figure 2 is a diagrammatic view illustrating the heat exchange element of the assembly shown in Figure 1; and Figure 3 is a diagrammatic view illustrating an alternative embodiment.

Referring firstly to Figures land 2 of the accompanying drawings, a heat exchange assembly 10 is illustrated comprising a housing 12 of generally hollow cylindrical form and including a base 14, and cylindrical outer wall 16 and a lid 18. The components of the housing 12 are fluidically sealed to one another, for example by being welded or the like to one another. As illustrated, the outer wall 16 is provided with an opening 16a whereby a cooling fluid, for example in the form of helium gas or the like, can be supplied to the interior of the housing 12, and the lid 18 is formed with an opening 18a whereby fluid can escape from the housing 12.

The housing 12 is designed in such a manner that the base 14 thereof can be secured to a device to be cooled, in use, for example to the housing of an electromagnet or the like. It will be appreciated, however, that the invention is not restricted to such use and may be employed in other applications in which heating or cooling of a device is required. Conveniently, the housing 12 is clamped in position, in use, with the base 14 thereof in good thermal contact with the device to be cooled or heated. However, other fastening techniques may be used.

Located within the housing 12 is a heat exchange element 20. The element 20 takes the form of a one piece body 20a fabricated using an additive manufacturing process to integrally form a heat transfer section 22 thereof with a base section 24. The heat transfer section 22 is designed to have a structure that has the appearance of an open cell foam structure, defining a series of interconnected convoluted passages 22a that extend through the heat transfer section 22 of the body 20a. The structure may be of a pseudo-random form. However, it will be appreciated that this need not be the case, and the structure could be of a more regular form, for example including a series of passages that interconnect repeatedly with one another within the body, the passages conveniently following a regular pattern. The base section 24 is of solid form, having a thickness of at least 0.5mm, preferably 1-2mm. As the base section is integrally formed with the heat transfer section 22, it will be appreciated that good thermal transfer therebetween is achieved, heat energy being conducted, primarily, between parts of the heat transfer section 22 and parts of the base section 24, in use, although some heat transfer may occur via other heat transfer mechanisms.

If desired, the passages 22a may be shaped to define a periodic minimal surface type structure.

Such an arrangement has the advantage that the surface area of the passages 22a may be optimised or maximised for a given fluid flow rate, thereby enabling optimisation or maximisation of the heat exchange characteristics of the assembly.

The passages 22a may be shaped, if desired, to promote turbulence in the fluid flow therein and/or to control the fluid flow rate. In each case, these characteristics may serve to enhance the heat exchange characteristics of the assembly.

The heat exchange element 20 is preferably fabricated from copper or another suitable metallic material, or another material of good thermal conduction properties. It may be fabricated using a laser sintered, powder bed based technique. However, the invention is not restricted in this regard and other additive manufacturing or 3D printing techniques may be used.

The heat exchange element 20 is introduced into the housing 12 prior to completion of the assembly of the housing 12, for example prior to the attachment of the lid 18 thereto. The heat exchange element 20 is secured in position by having the base section 24 thereof soldered to the base 14 of the housing 12. As the base section 24 is of solid form, and preferably has a smooth flat bottom surface conforming with the shape of the corresponding surface of the base 14, it will be appreciated that soldering of these components to one another in such a manner as to achieve a good thermal contact therebetween is a relatively straightforward process.

Whilst soldering represents a convenient technique for securing the heat exchange element 20 in position in good thermal contact with the base 14, it could be secured by, for example, clamping or the like if desired.

In use, a cold fluid such as cold helium gas is passed through the housing 12, flowing through the convoluted passages defined by the heat transfer section 22 of the heat exchange element 20. As a consequence, the heat transfer section 22 is cooled. As the heat transfer section is integrally formed with the base section 24, and the heat exchange element 20 is of a material of good thermal conduction properties, it will be appreciated that the base section 24 is also cooled by the flow of cooling gas through the housing 12. The base section 24, being in good thermal contact with the base 14 by virtue of the good quality soldered connection therebetween, is also cooled as a result, and the device to which the housing 12 is secured is thus also cooled.

It will be appreciated that through the use of the invention, manufacture and assembly of a heat exchange assembly may be simplified and manufacturing efficiency may be enhanced. As the invention allows the formation of a good thermal connection between the heat exchange element 20 and the base 14 of the housing 12, enhanced operating efficiency may also be achieved. As a consequence, it may be possible to use a smaller heat exchange assembly than would otherwise be necessary to achieve a given level of cooling or heating, and a smaller quantity of cooling or heating fluid may be required, again leading to enhanced operating efficiency and to environment benefits.

The heat exchange assembly, and heat exchange element used therein, is advantageous in that the thermal connection between the heat exchange element and the base of the housing may be of consistent form, and so the performance of a plurality of similar heat exchange assemblies will be of a good level of consistency. Furthermore, through manufacturing of the heat exchange element to a given design, for example using an additive manufacturing approach as set out hereinbefore, the consistent performance of the heat exchange elements and assemblies using them can be further enhanced.

Figure 3 illustrates an alternative embodiment of the invention. In the arrangement of Figure 3, a pair of heat exchange elements 20a, 20b are provided with the base sections 24a, 24b thereof soldered or otherwise secured to one another. The heat exchange elements 20a, 20b are substantially of the form described hereinbefore. The heat exchange elements 20a, 20b are located within a housing 12 that is divided into a first housing chamber 12a and a second housing chamber 12b, with one of the heat exchange elements 20a located within the first chamber 12a and the other of the heat exchange elements 20b located within the second chamber 12b. Each of the chambers 12a, 12b is provided with respective inlet and outlet ports 16a', 16a", 18a', 18a". The base sections 24a, 24b, being solid, serve to isolate the chambers 12a, 12b from one another. In use, thermal energy extracted from hot gases flowing through the first chamber 12a can pass, via the interconnected heat exchange elements 20a, 20b, to the second chamber 12b and serve to heat the gases flowing through the second chamber 12b. By way of example, therefore, the arrangement of Figure 3 may be used to extract heat energy from exhaust gases and preheat inlet gases.

Alternatively, a pair of assemblies of the type shown in Figure 1 may be arranged with their bases 14 abutting one another to achieve substantially the same effect.

Whilst the description hereinbefore is of specific embodiments of the invention, it will be appreciated that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A heat exchange element comprising a body including a heat transfer section defining at least one convoluted flow path through the heat transfer section, the heat transfer section being integrally formed with a solid base section.
2. An element according to Claim 1, wherein the body is manufactured using an additive manufacturing or 3D printing technique.
3. An element according to Claim 2, wherein a laser sintering, powder bed technique is used.
4. An element according to any of the preceding claims, wherein the heat transfer section is of a form having the appearance of an open cell foam defining at least one the convoluted flow path through the body.
5. An element according to any of Claims 1 to 3, wherein the convoluted flow path is defined by a regularly arranged series of individual flow paths through the body.
6. An element according to Claim 5, wherein the individual flow paths interconnect repeatedly with one another within the body.
7. An element according to any of Claims 1 to 3, 5 and 6, wherein the flow paths define a periodic minimal surface.
8. An element according to any of the preceding claims, wherein the base section has a thickness of at least 0.5mm.
9. An element according to any of the preceding claims, wherein the base section has a thickness in the range of 1-2mm.
10. An element according to any of the preceding claims, wherein the base section is of smooth flat form.
11. An element according to any of the preceding claims, wherein the body is of a material of high thermal conductivity.
12. An element according to Claim 11, wherein the body is of a metallic material.
13. A heat exchange assembly comprising a housing having a base, and a heat exchange element as claimed in any of the preceding claims located within the housing and secured in such a manner that the base section thereof is in thermal contact with the base.
14. An assembly according to Claim 13, wherein the base section is soldered to the base.
15. A method of manufacture of a heat exchange element as claimed in any of the preceding claims, the method comprising the steps of using an additive manufacturing process to integrally form a heat transfer section, defining at least one convoluted flow path through the heat transfer section, with a solid base section.