Method of manufacturing a heat exchanger

Abstract

A method of manufacturing a heat exchanger comprising a body and a support embedded within the body. The support comprises a different material and/or a different material structure to the body and hence has at least one material property which is different to that of the body. The method comprises; forming at least a first portion of the support with a first material and a first material structure using a first additive manufacturing step; and forming at least a first portion of the body with a second material and a second material structure using a second additive manufacturing step. The first material is different to the second material and/or the first material structure is different to the second material structure.

Claims

1. A method of manufacturing a heat exchanger comprising a body and a support embedded within the body, wherein the support comprises a different material and/or a different material structure to the body and hence has at least one material property which is different to that of the body, the method comprising; forming at least a first portion of the support with a first material and a first material structure using a first additive manufacturing step; and forming at least a first portion of the body with a second material and a second material structure using a second additive manufacturing step; wherein the first material is different to the second material and/or the first material structure is different to the second material structure; wherein the first additive manufacturing step uses a first additive manufacturing technique, and the second additive manufacturing step uses a second additive manufacturing technique which is different to the first additive manufacturing technique; wherein the first additive manufacturing step comprises an extrusion additive manufacturing process; and wherein the second additive manufacturing step comprises a powder bed process.

2. The method as claimed in claim 1, wherein the step of forming at least a first portion of the body comprises; providing a powder coating about the first portion of the support; and melting the powder to form the portion of the body.

3. The method as claimed in claim 1, comprising; forming a second portion of the support using the first additive manufacturing step after forming the first portion of the body using the second additive manufacturing step; and forming a second portion of the body using the second additive manufacturing step after forming the second portion of the support using the first additive manufacturing step.

4. The method as claimed in claim 1, comprising machining the first portion of the support and/or machining the first portion of the body.

5. The method as claimed in claim 1, comprising, after the support has been fully formed, forming a further portion of the body so as to completely enclose the support within the body.

6. The method as claimed in claim 1, comprising forming the support so that it has a greater thermal conductivity than the body; and/or forming the support so that it has a greater strength and/or stiffness than the body.

7. The method as claimed in claim 1, comprising selecting a material to form the first portion of the support and selecting a different material to form the first portion of the body so as to prevent galvanic corrosion of the body and support.

8. The method as claimed in claim 1, comprising forming at least a portion of the support as an internal beam.

Description

(1) An embodiment of the invention is described in detail below by way of example only and with reference to the accompanying drawings in which:

(2) FIG. 1A shows a heat exchanger with fluid flows indicated;

(3) FIG. 1B shows a thermal map of the heat exchanger of FIG. 1A;

(4) FIG. 2 shows a schematic of a support, and a schematic of the same support disposed within a body; and

(5) FIG. 3 shows a schematic of a process of manufacturing a heat exchanger.

(6) FIG. 1A shows a perspective view of a heat exchanger 10, with a cold fluid flow 11 and a hot fluid flow 12 passing therethrough so as to exchange heat. FIG. 1B shows thermal image of the same heat exchanger 10. During use the region of the heat exchanger 10 where the hot fluid flow 12 enters is at a significantly higher temperature than the rest of the heat exchanger 12. Such concentrations of heat in specific regions can lead to failure of the heat exchanger due to thermal and mechanical stresses.

(7) FIG. 2 shows a heat exchanger 100 comprising a body 110 and an embedded support 120. The support 120 can be shaped as required to be embedded within the body 110 of the heat exchanger. The support 120 is shown as defining the edges of a cube, though a grid, or concentric circular, or radial arrangement for the support 120 may also be suitable for a desired purpose. Two such alternatives are shown at the top of FIG. 2. As can be seen from FIG. 2, the support 120 is shaped as necessary to complement the geometry of the heat exchanger body 110. In the depicted case, the support 120 defines the edges of a cube, while the body 110 defines a larger cube, in which the support 120 is embedded.

(8) The body 110 shown in FIG. 2 is solid, with the support 120 embedded therein and fused thereto. However, the body 110 and support 120 can be formed by additive manufacturing so that the necessary channels for fluid flow are also defined therein.

(9) The material making up the support 120 of FIG. 2 is more costly than the material making up the body 110. In this example the support 120 comprises titanium (which may be as a titanium alloy) and the body 110 comprises aluminium (which may be as an aluminium alloy). The support 120 has a higher heat conductivity than does the body 110. Therefore, if a corner of the body 110 is heated, the heat will be conducted transmitted through the body 110 into the support 120. The support 120 will then conduct the heat at a faster rate than does the body 110, dissipating the heat throughout the entire heat exchanger 100 more rapidly than the material of the body 110 is capable of doing.

(10) The support 120 is also stronger and stiffer than the material of the body 110. The heat exchanger 100 thus has improved mechanical strength and stiffness, and is hence more durable.

(11) The support 120 is entirely contained within the body 110 and no part is exposed to the external environment. The issues of galvanic corrosion associated with dissimilar metals contacting each other can therefore be avoided.

(12) FIG. 3 shows various stages A to F of a method of manufacturing a heat exchanger 100. The method is carried out using an additive manufacturing system 200. At stage A, a first portion of the support 120 is formed by a fused deposition modelling device 210. At stage B a powder coating is applied to around the portion of the support 120 by a powder bed additive manufacturing device 220. In stage C the powder is fused to form a portion of the body 110. The portion of the body 110 is fused to the portion of the support 120. At stage D, the portion of the heat exchanger 100 comprising the portion of the support 120 and the portion of the body 110 is machined using computer numeric control machining.

(13) Depending on whether the heat exchanger is completed, the method may return to stage A or progress to stage E. If the heat exchanger is not complete, the method returns to stage A and another portion of the support 120 is formed by the fused deposition modelling device 210, followed by another portion of the body 110 formed by the powder bed additive manufacturing device 220. Another layer of the heat exchanger 100 is thus formed. The heat exchanger 100 shown in FIG. 3 comprises a plurality of layers, and hence repetition of stages A to D is needed a plurality of times.

(14) Once the support 120 is completed, stage A may be skipped so that consecutive layers of the body 110 are formed in order to embed the support 120 within the body 110 and close the support 120 off from the atmosphere.

(15) Once the heat exchanger 100 is complete, the method progresses to stage E in which the completed heat exchanger 100 is finished. In stage F the heat exchanger 100 is removed from the additive manufacturing system 200 and is ready to use.

(16) While FIGS. 2 and 3 show a schematic heat exchanger, the support 120 may be formed in any shape as needed to be disposed within the body 110. For example, the heat exchanger shown in FIG. 1A might have a support 120 radiating in all dimensions away from the point of entry of the hot fluid flow 12 so as to increase the distribution of heat from that region. The support 120 may be disposed in a U-shape about the hot fluid flow 12 along its entire length within the body 110 of the heat exchanger 100. The support 120 may be shaped for enhanced strength and/or stiffness. For example it may be formed as a truss or other beam type structure, such as an I or T cross-section, to thereby enhance the structural characteristics of the heat exchanger by acting as an internal beam. The desired shape of the support 120 will be determined by the design of the heat exchanger 100 in which it is embedded.