Heat exchanger assembly

Abstract

A heat exchanger assembly 100 comprises a first fluid duct 200 for a first fluid 202, the duct defining a first fluid inlet 204 and a first fluid outlet 206 spaced apart along direction L of the duct.

Description

The present disclosure relates to a heat exchanger assembly. In particular the disclosure is concerned with a heat exchanger assembly for a vehicle. Background Radiator heat exchangers are commonly used on vehicles to reject waste heat (for example from a vehicle engine) to the atmosphere, by transferring heat from a working fluid passing through the radiator to atmospheric air via the structure of the radiator. In some installations, radiators are approximately flat cuboids with a large face area, arranged perpendicular to the air flow. Such arrangements may require large frontal areas for installation which is undesirable in terms of its impact on the packaging, mass, and aerodynamic drag of a vehicle. In some examples, to reduce the frontal area required, the heat exchanger may be arranged as an annular drum whereby the air enters axially, flows through the heat exchanger radially, and then exits axially. This may permit a reduction in installed frontal area compared to a flat cuboid heat exchanger. However, in this arrangement there will be a pressure loss as the flow is turned from axial to radial, and this pressure loss is primarily a function of the axial blockage at inlet and outlet. In some examples, to reduce axial flow blockage and the associated pressure loss, heat exchangers are arranged as a series of annular drums of increasing diameter, for example as shown in GB2519147A. This reduces the axial blockage at inlet and outlet and provides a relatively large face area through the heat exchanger, in order to provide a low pressure drop in as compact an installation as possible. Vehicle performance is a driver to minimise weight and size of vehicle systems while maintaining or improving their performance, and radiator heat exchangers are no exception to this. This requirement is particularly relevant to high performance automobiles and / or fast jet aircraft. In such examples, it is also desirable that the radiator system should not significantly contribute to aerodynamic drag on the vehicle. Hence a heat exchanger assembly which is more compact and efficient that arrangements of the related art, while also causing low levels of aerodynamic drag, is highly desirable. Summary According to the present disclosure there is provided an apparatus as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. Accordingly there may be provided a heat exchanger assembly (100). The heat exchanger assembly (100) may comprise a first fluid flow duct (200) for the passage of a first fluid (202) therethrough, wherein the first fluid flow duct (200) defines a first fluid flow inlet (204) and a first fluid flow outlet (206) spaced apart from one another along a length direction (L) of the first fluid flow duct (200). The heat exchanger assembly (100) may comprise a first heat exchanger module (300) having a leading-edge end (306) and a trailing edge end (308), the leading-edge end (306) and the trailing edge end (308) spaced apart from one another along the length direction (L) of the first fluid flow duct (200). The first heat exchanger module (300) may have a flow inlet face (310) and a flow outlet face (312) which extend between the leading-edge end (306) and the trailing edge end (308) along the length direction (L) of the first fluid flow duct (200). The first fluid flow duct flow inlet (204), the first heat exchanger module flow inlet face (310), the first heat exchanger module flow outlet face (312), and the first fluid flow outlet (206) may be provided in series along the length direction (L) of the first fluid flow duct (200) to define a first fluid flow path (210) through the first fluid flow duct (200) The heat exchanger assembly (100) may further comprise a support member (400) located within, and spaced apart from, the first fluid flow duct (200) such that the support member (400) defines at least part of the first fluid flow path (210). The first heat exchanger module (300) may extend across the first fluid flow duct (200) from a first side edge (302) located on the first fluid flow duct (200) to a second side edge (304) located on the support member (400). The first heat exchanger module (300) may comprise a second fluid flow inlet (320) for receiving a second fluid (330) from a heat sink / source (332). The first heat exchanger module (300) may comprise a second fluid flow outlet (322) for delivering the second fluid (330) to the heat sink / source (332). The second fluid (330) may be fluidly isolated from, and different to, the first fluid (202). The heat exchanger assembly (100) may comprise a plurality of heat exchanger modules (300). The first heat exchanger module (300) may be one of the plurality of heat exchanger modules (300). Each heat exchanger module (300) may have a leading-edge end (306) and a trailing edge end (308), each leading-edge end (306) spaced apart from its respective trailing edge end (308) along the length direction (L) of the first fluid flow duct (200). Each heat exchanger module (300) may have a flow inlet face (310) and a flow outlet face (312) which extend between the leading-edge end (306) and a trailing edge end (308) along the length direction (L) of the first fluid flow duct (200). The first fluid flow duct flow inlet (204), each heat exchanger module flow inlet face (310), each first heat exchanger module flow outlet face (312), and the first fluid flow outlet (206) may be provided in series along the length direction (L) of the first fluid flow duct (200) to define the first fluid flow path (210) through the first fluid flow duct (200). Each heat exchanger module (300) may extend across the first fluid flow duct (200) from a first side edge (302) located on the first fluid flow duct (200) to a second side edge (304) located on the support member (400). Each heat exchanger module (300) may comprise a second fluid flow inlet (320) for receiving a second fluid (330) from a heat sink / source (332). Each heat exchanger module (300) may comprise a second fluid flow outlet (322) for delivering the second fluid (330) to a heat sink / source (332). The support member (400) may define and / or house a second fluid passage (404). The second fluid flow inlet (320) may be in fluid communication with the heat sink / source (332) via the second fluid passage (404). The second fluid flow outlet (322) may be in fluid communication with the heat sink / source (332) via the second fluid passage (404). A plurality of microtubes (340) may provide fluid communication between the second fluid flow inlet (320) and the second fluid flow outlet (322), each microtube (340) defining a second fluid flow path (350). A plurality of layers (342) of microtubes (340) may define the flow path extending between the first heat exchanger module flow inlet face (310) and the first heat exchanger module flow outlet face (312). A first pair (360) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) may be arranged such that their leading-edge ends (306) are coupled together and their trailing edge ends (308) are spaced apart such that the first pair (360) of heat exchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween. A first pair (360) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) may be arranged such that the flow outlet face (312) of each of the first pair (360) of heat exchanger modules (300) face one another to define sides of the first fluid outlet passage (362). A second pair (370) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) may be arranged such that their leading-edge ends (306) are coupled together and their trailing edge ends (308) are spaced apart such that the second pair (370) of heat exchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween. The flow outlet face (312) of each of the second pair (370) of heat exchanger modules (300) may face one another to define sides of the first fluid outlet passage (362). One of the heat exchanger modules (300) of the first pair (360) and one of the heat exchanger modules (300) of the second pair (370) may be spaced apart from one another at their leading-edge end (306) and coupled together at their trailing edge end (308), with their flow inlet faces (310) facing one another such that they converge along the length direction (L) of the first fluid flow duct (200) to define a first fluid inlet passage (364) therebetween. A plurality of pairs (360, 370) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) may be arranged such that the leading-edge ends (306) of each pair (360, 370) are coupled together and the trailing-edge ends (308) of each pair are spaced apart such that each pair (360, 370) of heat exchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween. The flow outlet face (312) of each pair (360, 370) of heat exchanger modules (300) may face one another to define sides of their respective first fluid outlet passage (362). Each heat exchanger module (300) of each pair (360, 370) is spaced apart from an adjacent heat exchanger module (300) at their leading-edge end (306) and coupled to the adjacent heat exchanger module (300) at their trailing edge end (308), with their flow inlet faces (310) facing one another such that they converge along the length direction (L) of the first fluid flow duct (200) to define a first fluid inlet passage (364) therebetween. The pairs (360, 370) may be provided in series around the support member (400). A first pair (360) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) may be arranged such that they are spaced apart from one another along their length to define a first fluid flow chamber (380) therebetween. A divider plate (382) may be provided between the first pair (360) of heat exchanger modules (300) which extends from the leading-edge end (306) of one of the pair (360) of heat exchanger modules (300) to the trailing edge end (308) of the other of the pair (360) of heat exchanger modules (300) to divide the first fluid flow chamber (380) into a first sub-chamber (384) and a second flow chamber (386). The divider plate (382) may face a flow inlet face (310) of one of the first pair (360) of heat exchanger modules (300) and facing a flow outlet face (312) of the other of the first pair (360) of heat exchanger modules (300). The plurality of heat exchanger modules (300) may be arranged such that they are spaced apart from one another along their length to define a first fluid flow chamber (380) therebetween. A divider plate (382) may be provided between each pair (360, 370) of adjacent heat exchanger modules (300). Each divider plate (382) may extend from the leading-edge end (306) of one of the adjacent heat exchanger modules (300) to the trailing edge end (308) of the other heat exchanger module (300) of the pair of adjacent heat exchanger modules (300) to divide the first fluid flow chamber (380) into a first sub-chamber (384) and a second flow chamber (386). Each divider plate (382) may face a flow inlet face (310) of one of the adjacent heat exchanger modules (300) and facing a flow outlet face (312) of the other of the adjacent heat exchanger modules (300). Each of the heat exchanger modules (300) may be aligned with the length direction (L) of the first fluid flow duct (200). Each of the divider plates (382) may be aligned with the length direction (L) of the first fluid flow duct (200). Each of the divider plates (382) may be planar. Each of the divider plates may curve along their width between the first fluid flow duct (200) and the support member (400) and / or curve along their length between their leading-edge end (306) and their trailing edge end (308). The or each heat exchanger module (300) may be planar. The or each heat exchanger module (300) may curve along its width between the first side edge (302) and the second side edge (304) and / or curve along its length between the leadingedge end (306) and the trailing edge end (308). The leading-edge end (306) of the heat exchanger module (300) may comprise a second fluid flow inlet duct (500) configured to deliver the second fluid (330) to the second fluid flow inlet (320) of the heat exchanger module (300). The trailing edge end (308) of the heat exchanger module (300) may comprise a second fluid flow outlet duct (502) configured to receive the second fluid (330) from the second fluid flow outlet (322) of the heat exchanger module (300). The plurality of microtubes (340) may extend from the second fluid flow inlet duct (500) to the second fluid flow outlet duct (502) of the heat exchanger module (300). A second fluid passage (404) in the support member (400) may be configured to deliver the second fluid (330) to the second fluid flow inlet duct (500). The support member (400) may define and / or house a second fluid exhaust passage (406) configured to receive the second fluid (330) from the second fluid flow outlet duct (502). The second fluid flow inlet duct (500) may extend through the first fluid flow duct (200). The second fluid flow outlet duct (502) may extend through the first fluid flow duct (200). The plurality of microtubes (340) may extend from the first side edge (302) of the heat exchanger module (300) to the second side edge (304) of the heat exchanger module (300). A second fluid passage (404) in the support member (400) may be configured to deliver the second fluid (330) to the second fluid flow inlet (320) of the heat exchanger module (300). The first side edge (302) of the heat exchanger module (300) may comprise a second fluid flow outlet duct (502) in fluid communication with the second fluid flow outlet (322). The second fluid flow outlet duct (502) may extend through the first fluid flow duct (200). The first side edge (302) and leading-edge end (306) of the heat exchanger module (300) may comprise a second fluid flow outlet duct (502) in fluid communication with the second fluid flow outlet (322), and the second fluid flow outlet duct (502) may terminate at the support member (400). The first side edge (302) and trailing edge end (308) of the heat exchanger module (300) may comprise a second fluid flow outlet duct (502) in fluid communication with the second fluid flow outlet (322), and the second fluid flow outlet duct (502) may deliver the second fluid (330) to a second fluid exhaust passage (406) provided in the support member (400). A first section (520) of the first side edge (302) may comprise a second fluid flow outlet duct (502) which is configured to receive the second fluid (330) from a first section (520) of microtubes (340) and configured to deliver the second fluid (330) to a second section (522) of microtubes (540) which are configured to deliver the second fluid (330) to a second fluid exhaust passage (406) via the second fluid flow outlet (322), the second fluid exhaust passage (406) being provided in the support member (400). The second fluid flow inlet (320) and the second fluid flow outlet (322) of the heat exchanger module (300) may be provided at the first side edge (302). The plurality of microtubes (340) may first extend from the first side edge (302) to the second side edge (304) and then return to the first side edge (302) in repeating pattern which extends along the extent of the first side edge (302) and second side edge (304). The first fluid flow duct (200) may be cylindrical. The length (L) of the first fluid flow duct (200) may be greater than its diameter (D). The first fluid flow duct (200) and the support member (400) may be coaxial and / or concentric. The or each heat exchanger module (300) may extend radially from the support member (400) to the first fluid flow duct (200). There may be provided a system (600) comprising a heat exchanger assembly (100) according to the present disclosure wherein the system (600) is provided as a land, sea or air vehicle. The system (600) may comprise a first fluid flow intake (602) and an first fluid flow outlet (610), wherein the system first fluid flow intake (602), heat exchanger assembly first fluid flow inlet (204), heat exchanger assembly first fluid flow outlet (206) and system first fluid flow outlet (610) are provided in series to define a first fluid flow path (606). The system (600) may further comprise a first fluid inlet duct (604) extending from the system fluid flow intake (602) to the heat exchanger assembly first fluid flow inlet (204). The system (600) may further comprise a first fluid outlet duct (608) extending from the heat exchanger assembly first fluid flow outlet (206) to the system first fluid flow outlet (610). The system first fluid inlet duct (604), heat exchanger assembly (100) and system first fluid outlet duct (608) may be provided in series to define the first fluid flow path (606). By virtue of the orientation of the heat exchanger module(s) 300 in the flow duct 200, a heat exchanger assembly according to the present disclosure provides a very large flow area and a very low axial blockage, particularly at the first fluid flow inlet 204 and the first fluid flow outlet 206 where all the air is flowing axially. A heat exchanger assembly configuration according to the present disclosure may thus be more compact and / or more efficient, as well as causing less aerodynamic drag, than examples of the related art. Brief Description of the Drawings Examples of the present disclosure will now be described with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic representation of a first example of a system comprising a heat exchanger assembly according to the present disclosure; Figure 2 shows a diagrammatic representation of a second example of a system comprising a heat exchanger assembly according to the present disclosure; Figure 3 shows a diagrammatic representation of a third example of a system comprising a heat exchanger assembly according to the present disclosure; Figure 4 shows a sectional view of an example of a heat exchanger assembly according to the present disclosure; Figures 5 to 9 illustrate a first example of a heat exchanger assembly according to the present disclosure; Figures 10 to 16 illustrate a second example of a heat exchanger assembly according to the present disclosure; Figures 17 to 20 illustrate a third example of a heat exchanger assembly according to the present disclosure; Figures 21 to 23 illustrate a fourth example of a heat exchanger assembly according to the present disclosure; Figures 24 to 32 illustrate different manifold arrangements for the examples of heat exchanger assemblies; Figure 33 illustrates a side sectional view through a heat exchanger assembly in which the second fluid flows axially; Figure 34 illustrates a side sectional view through a heat exchanger assembly in which the second fluid flows radially; Figure 35 shows a sectional view though an example of a heat exchange structure; and Figure 36 shows a sectional view though a further example of a heat exchange structure; Detailed Description The present disclosure relates to a heat exchanger assembly 100. The heat exchanger assembly 100 may form part of (e.g. be fitted to or formed integrally with) a system 600. By way of non-limiting example, the system 600 may be provided as a building, a vehicle or an engine. Hence, as illustrated in figure 1, there may be provided a system 600 comprising a heat exchanger assembly 100 according to the present disclosure. In examples in which the system 600 is provided as a vehicle, the system 600 may be a land, sea or air vehicle. For example the vehicle may be provided as a road or rail vehicle, a watercraft or an aircraft. As illustrated in the figures for each of the examples, the heat exchanger assembly 100 may comprise a first fluid flow duct 200 for the passage of a first fluid 202 therethrough. The first fluid flow duct 200 may define a central axis 212. The first fluid flow duct 200 may comprise an outer casing 220. The first fluid flow duct 200 may define a first fluid flow inlet 204 and a first fluid flow outlet 206 spaced apart from one another along a length direction L of the first fluid flow duct 200. The length direction L is an axial length of the first fluid flow duct 200, which is aligned with and / or parallel to the central axis 212. The first fluid flow duct 200 may be cylindrical. The length L of the first fluid flow duct 200 may be greater than its diameter D. The outer casing 220 may have any practical diameter and length (for example sized in relation to the first fluid flow duct 200 so the heat exchanger assembly 100 may achieve the required heat transfer and / or fit within a required space envelope). By way of non-limiting example, the outer casing 200 may have a diameter in the range of 50mm, with a length of 200mm, to a diameter of 250mm, with a length of 1000 mm. By way of non limiting example, the outer casing 200 may have a diameter of 175 mm and a length of 700 mm long. The heat exchanger assembly 100 may comprise a first heat exchanger module 300 having a leading-edge end 306 and a trailing edge end 308, the leading-edge end 306 and the trailing edge end 308 spaced apart from one another along the length direction L of the first fluid flow duct 200. The leading-edge end 306 may be proximate to the first fluid flow inlet 204. The leadingedge end 306 may be close to but spaced apart from the first fluid flow inlet 204. The trailing edge end 308 may be proximate to the first fluid flow outlet 206. The trailing edge end 308 may be close to but spaced apart from the first fluid flow outlet 206. The leading-edge end 306 may be located at the first fluid flow inlet 204. The trailing edge end 308 may be located at the first fluid flow outlet 206. The heat exchanger assembly 100 may further comprise a support member 400 located within, and spaced apart from, the first fluid flow duct 200. The support member 400 may have an outer surface 402. The support member 400 may be a tube with its central axis coincident with, or approximately coincident with, the central axis 212 of the outer casing 220. The axial extent of the support member 400 may be at least as great as the axial extent ofthe heat exchanger module 300. The first heat exchanger module 300 may extend across the first fluid flow duct 200 from a first side edge 302 located on the first fluid flow duct 200 to a second side edge 304 located on / at the support member 400. The first side edge 302 and the second side edge 304 may extend along the length direction L ofthe first fluid flow duct 200. The or each heat exchanger module 300 may extend away from the support member 400 to the first fluid flow duct 200. The or each heat exchanger module 300 may extend radially from the support member 400 to the first fluid flow duct 200. The leading-edge end 306 and trailing edge end 308 ofthe first heat exchanger module 300 may extend across the first fluid flow duct 200 from the first fluid flow duct 200 to the support member 400. Hence the heat exchanger assembly 100 may sit within the outer casing 220. The first fluid flow duct 200 and / or the support member 400 may be centred on the central axis 212. The first fluid flow duct 200 and the support member 400 may be coaxial and / or concentric. In other examples, not shown, the support member 400 may be offset from the central axis 212. The support member 400 may be supported by, and fixed relative, to the outer casing 220. The support member 400 may be supported by, and fixed relative to, the outer casing 220 by the heat exchanger modules 300. As illustrated in figure 4 the first heat exchanger module 300 may have a flow inlet face 310 and a flow outlet face 312 which extend between the leading-edge end 306 and the trailing edge end 308 along the length direction L ofthe first fluid flow duct 200. As illustrated in figure 4, the first fluid flow duct flow inlet 204, the first heat exchanger module flow inlet face 310, the first heat exchanger module flow outlet face 312, and the first fluid flow outlet 206 are provided in series along the length direction L ofthe first fluid flow duct 200 to define a first fluid flow path 210 through the first fluid flow duct 200. The first fluid flow duct flow inlet 204, the leading-edge end 306, the first heat exchanger module flow inlet face 310, the first heat exchanger module flow outlet face 312, the trailing edge end 308, and the first fluid flow outlet 206 may be provided in series along the length direction L of the first fluid flow duct 200 to define the first fluid flow path 210 through the first fluid flow duct 200. Hence a flow path 210 is defined to direct all of the first fluid 202 passing along the first flow duct 200 through the heat exchanger module 300, to thereby undergo heat transfer to or from the heat exchanger module 300. The outer surface 402 of the support member 400 may define at least part of the first fluid flow path 210. Hence the first fluid flow path 210 may (at least in part) be defined by the outer surface 402 of the support member 400 and the inner surface of the outer casing 220. As illustrated in figures 1 to 3, 24 to 34, the first heat exchanger module 300 may comprise a second fluid flow inlet 320 for receiving a second fluid 330 from a second fluid reservoir 332. The first heat exchanger module 300 may comprise a second fluid flow outlet 322 for delivering the second fluid 330 to the second fluid reservoir 332. The second fluid 330 may be fluidly isolated from, and different to, the first fluid 202. The second fluid reservoir 332 may be provided as a heat sink (for example a source of second fluid 330 at a lower temperature than the first fluid 202). The second fluid reservoir 332 may be provided as a heat source (for example a source of second fluid 330 at a higher temperature than the first fluid 202). The heat source may be a heat generating component, or combination of heat generating components, of the system 600 such as its engine, battery, fuel cell, motor(s), brakes, and / or air conditioning unit. As illustrated in figure 13, in which a wall which defines the support member 400 has been removed, and in figures 33, 34, the support member 400 may define and / or house a second fluid passage 404. The support member 400 may house a tube which defines the second fluid passage 404. The support member 400 may house a plurality of parallel tubes which each define a second fluid passage 404. The support member 400 may comprise a plurality of parallel tubes which each define a second fluid passage 404. Each tube of the plurality of tubes may feed one or more of the heat exchanger modules 300. The support member 400 may have any practical diameter and length (for example sized in relation to the first fluid flow duct 200 so the heat exchanger assembly 100 may achieve the required heat transfer and / or fit within a required space envelope). By way of non-limiting example, the support member 400 may be circular in cross section, with an outer diameter in the range of 25-50 mm. Ideally the size of the support member 400 should be minimised as much as possible whilst keeping the pressure drop of the second fluid 330 passing along the support member 400 within acceptable limits. The support member 400 may also have a different cross section with a degree of rotational symmetry, in order to better align its surface with the heat exchanger modules 300 joining it. The second fluid flow inlet 320 may be in fluid communication with the heat sink / source 332 via the second fluid passage 404. Hence the second fluid flow inlet 320 is operable to receive the second fluid 320 from the heat sink / source 332 via the second fluid passage 404. For example, the second fluid flow inlet 320 may be operable to receive the second fluid 320 from the heat sink / source 332 via a tube or tubes which define the second fluid passage 404 which are in fluid communication with the heat sink / source 332. The second fluid flow outlet 322 may be in fluid communication with the heat sink / source 332 via the second fluid passage 404. Hence the second fluid flow outlet 322 is operable to deliver the second fluid 320 to the heat sink / source 332 via the second fluid passage 404. For example, second fluid flow outlet 322 may be operable to deliver the second fluid 320 to the heat sink / source 332 via the second fluid passage 404 via a tube or tubes which define the second fluid passage 404 which are in fluid communication with the heat sink / source 332. The second fluid passage 404 may comprise a first section for delivery of the second fluid 330, and a second section for receipt of the second fluid 330 (for example as shown in figure 33). The heat exchanger module 300 may comprise a heat exchange structure 390 which provides fluid communication between the second fluid flow inlet 320 and the second fluid flow outlet 322, as well as defining a first fluid flow path between the heat exchanger module flow inlet face 310 and the heat exchanger module flow outlet face 312. As shown in figures 35, 36, the heat exchange structure 390 may be defined by a plurality of microtubes 340 that provide fluid communication between the second fluid flow inlet 320 and the second fluid flow outlet 322, each microtube 340 defining a second fluid flow path 350. Figures 35, 36 are diagrammatic. There may be provided fewer or more microtubes than that shown in figures 35, 36. Microtubes may be tubes of 0.3 - 2.0 mm outer diameter and 50 - 200 pm wall thickness. These microtubes are collectively referred to as a tube matrix. The microtubes are configured to permit the flow of the second fluid 330 therethrough. Their large surface area and small wall thickness serves to maximise the heat transfer between the first fluid 202 and the second fluid 330 whilst minimising the mass of the heat exchanger module 300. Hence, as illustrated in figure 4, the system is configured such that, in operation, the first fluid 202 (for example air) enters the first fluid flow inlet 204 of the heat exchanger assembly 100 and flows substantially / generally axially along the length L of the heat exchanger assembly 100, turns to flow in a substantially / generally circumferential direction through the heat exchange structure 390, and then turns again to flow substantially / generally axially towards and out of the first fluid flow outlet 206 of the heat exchanger assembly 100. Although the flow may be substantially / generally in the axial direction between the first fluid flow inlet 204 and the flow inlet face 310 of the heat exchange structure 390, and substantially / generally in the axial direction between the flow outlet face 312 of the heat exchange structure 390 and the first fluid flow outlet 206, there may be a small circumferential component to the direction of flow of the first fluid 202, for example due to the geometry of the flow duct 200. Likewise, although the flow of first fluid 202 may be substantially / generally in the circumferential direction between the flow inlet face 310 and flow outlet face 312 of the heat exchange structure 390, there may be a small axial component to the direction of flow of the first fluid 202 through the heat exchange structure 390, for example due to momentum of the first fluid 202 in the axial direction, or due to the flow path defined through the heat exchange structure 390. As shown in figures 35, 36, the plurality of layers 342 of microtubes 340 may define the flow path extending between the first heat exchanger module flow inlet face 310 and the first heat exchanger module flow outlet face 312. The microtubes 340 may therefore define a tube matrix. As illustrated in figure 33, the microtubes 340 may extend axially, i.e. parallel to the central axis 212, extending at least part of the distance between the leading-edge end 306 and trailing-edge end 308 of the heat exchanger module 300. As illustrated in figure 34 the microtubes 340 may extend radially at least part of the distance between the first side edge 302 and the second side edge 304 of the heat exchanger module 300. In an example in which the microtubes 340 extend radially, they may be straight or curved along their length. The microtubes 340 may run in a mainly axial direction, or a mainly radial direction. Axial tubes have the advantage of having a far smaller number of tubes, which generally serves to reduce manufacturing costs. However, as a result the second fluid 330 pressure drop may be comparatively higher than an arrangement in which the microtubes run radially. Hence there are advantages to both arrangements. Figures 35, 36 illustrate a sectional view through line A-A in figures 33, 34. As illustrated in figures 33, 34 the microtubes may be parallel to one another, at least along part of their length. As illustrated in figure 35, rows of parallel microtubes may be aligned so as to define a linear flow path through the tube matrix between the first heat exchanger module flow inlet face 310 and the first heat exchanger module flow outlet face 312. As illustrated in figure 36 rows of parallel microtubes may be staggered so as to define a convoluted flow path through the tube matrix between the first heat exchanger module flow inlet face 310 and the first heat exchanger module flow outlet face 312. As illustrated in figure 1, a system 600 which may include the heat exchanger 100 of the present disclosure may have a main body 620 (e.g. a support structure) upon which other parts of the system are mounted or housed within (for example a motor, engine, passenger compartment, wings, fuel tanks). As illustrated in figure 1, the system 600 may comprise a first fluid flow intake 602 and a first fluid flow outlet 610. The first fluid 202 may be the fluid that surrounds the system 600, for example air or water. The system first fluid flow intake 602, heat exchanger assembly first fluid flow inlet 204, heat exchanger assembly first fluid flow outlet 206 and system first fluid flow outlet 610 may be provided in series to define the first fluid flow path 210 through the system. The system 600 may comprise a first fluid inlet duct 604 extending from the system first fluid flow intake 602 to the heat exchanger assembly first fluid flow inlet 204. The system 600 may comprise a first fluid outlet duct 608 extending from the heat exchanger assembly first fluid flow outlet 206 to the system first fluid flow outlet 610. The system first fluid inlet duct 604, heat exchanger assembly 100 and system first fluid outlet duct 608 may be provided in series to define the first fluid flow path 210. In such an example, the objective of the heat exchanger assembly 100 is to transfer waste heat (for example from a heat generating component of a system such as its engine, battery, a motor, brakes, air conditioning unit) to the atmosphere, by transferring heat from the second fluid 330 passing through the heat exchange structure 390 to the first fluid 202 (e.g. atmospheric air). Hence in such an example the second fluid 330 is in heat transfer communication with the heat source 332. For example the second fluid 330 may be pumped around passages in the heat source 332, or is in heat transfer communication via a heat exchanger. The second fluid 330 in this (and the other examples) may be water, an ethylene glycol-water mixture (EGW), a hydrocarbon-based fuel, a dielectric fluid, an oil, a two phase refrigerant flow or any other suitable gas or fluid. Hence the first fluid 202 may be different to and / or in a different state to the second fluid 330. In other examples, as illustrated in figure 2, the heat exchanger assembly 100 may be provided in a fluid flow duct 900 with a first fluid flow intake 602 and a first fluid flow outlet 610. In this example the fluid duct 900 is provided as a bypass to a main first fluid flow duct 904, the first fluid flow intake 602 and fluid flow outlet 610 being in fluid communication with the main first fluid flow duct 904. The main fluid flow outlet 902 may comprise a valve 902 (for example provided as a pivotable / moveable flap) to control the mass flow through the fluid flow duct 900. In some examples, and as shown in figure 3, the heat exchanger assembly 100 of the present disclosure may be provided as part of a system 600 provided as an engine 700. The engine 700 may an engine comprising a first fluid flow intake 702, a combustor 800 with a combustor fluid flow intake 802 and a heat exchanger assembly 100 according to the present disclosure. In such an example the heat exchanger assembly first fluid flow inlet 204 may be in flow communication with and / or at least in part define the engine fluid flow intake 702. The heat exchanger assembly first fluid flow outlet 206 may be in flow communication with and / or at least in part define the combustor fluid flow intake 802. The engine fluid flow intake 702, heat exchanger assembly first fluid flow inlet 204, heat exchanger assembly first fluid flow outlet 206 and combustor fluid flow intake 802 may be provided in series to define the first fluid flow path 210 through the engine 700. In this example, the objective of the heat exchanger assembly 100 is to control temperature of the air (first fluid 202) going into the combustor 800, and hence may take heat from the air or add heat to the air depending on the air temperature at intake. Hence heat is transferred to / from the second fluid 330 passing through the heat exchanger assembly 300 to the air upstream of the combustor 800 to control the temperate of the intake air via the structure 390 of the heat exchanger assembly 100. The first fluid 202 may be delivered to the first fluid flow duct 200 by virtue of movement of the system 600 or device the heat exchanger assembly 100 it is connected to. For example, where the system 600 is located in a source of first fluid 202 (e.g. the atmosphere or water), the forward motion of the system 600 in / on the first fluid 202 may be sufficient to drive the first fluid 202 through the first flow duct 200. In further examples, a fan or compressor may be provided upstream of the heat exchanger module(s) 300 to blow / pump the first fluid 202 through the first flow duct 200. In other examples a pump may be provided downstream of the heat exchanger module(s) 300 to draw the first fluid 202 through the first flow duct 200. As illustrated in figures 5 to 23, the heat exchanger assembly 100 may comprise a plurality of heat exchanger modules 300, the first heat exchanger module 300 being one of the plurality of heat exchanger modules 300. Each heat exchanger module 300 may have a leading-edge end 306 and a trailing edge end 308, each leading-edge end 306 spaced apart from its respective trailing edge end 308 along the length direction L of the first fluid flow duct 200. There may be provided any number of heat exchanger modules 300. For example, the number of heat exchanger modules 300 may be chosen based on the size and shape of the first fluid flow duct 200 and the number to achieve the required heat transfer. By way of non limiting example, there may be provided at least one heat exchanger module 300 and at most sixteen. Each leading-edge end 306 may be proximate to the first fluid flow inlet 204. Each leadingedge end 306 may be close to but spaced apart from the first fluid flow inlet 204. Each trailing edge end 308 may be proximate to the first fluid flow outlet 206. Each trailing edge end 308 may be close to but spaced apart from the first fluid flow outlet 206. Each heat exchanger module 300 may have a flow inlet face 310 and a flow outlet face 312 which extend between the leading-edge end 306 and a trailing edge end 308 along the length direction L of the first fluid flow duct 200. The first fluid flow duct flow inlet 204, each heat exchanger module flow inlet face 310, each first heat exchanger module flow outlet face 312, and the first fluid flow outlet 206 may be provided in series along the length direction L of the first fluid flow duct 200 to define the first fluid flow path 210 through the first fluid flow duct 200. The first fluid flow duct flow inlet 204, each leading-edge end 306, each heat exchanger module flow inlet face 310, each first heat exchanger module flow outlet face 312, each trailing edge end 308 and the first fluid flow outlet 206 may be provided in series along the length direction L of the first fluid flow duct 200 to define the first fluid flow path 210 through the first fluid flow duct 200. Each heat exchanger module 300 may extend across the first fluid flow duct 200 from a first side edge 302 located on the first fluid flow duct 200 to a second side edge 304 located on the support member 400. The first side edge 302 and the second side edge 304 may extend along the length direction L of the first fluid flow duct 200. Each heat exchanger module 300 may comprise a second fluid flow inlet 320 for receiving a second fluid 330 from a second fluid reservoir 332. Each heat exchanger module 300 may comprise a second fluid flow outlet 322 for delivering the second fluid 330 to a second fluid reservoir 332. A second fluid pump may be provided to push or draw the second fluid 330 to / from the second reservoir 300 and through the heat exchanger module(s) 300. A first example of a heat exchanger assembly 100 according to the present disclosure is shown in figures 5 to 9. Figure 5 shows an external view of the heat exchanger assembly 100. Figure 6 shows an end on view of the heat exchanger assembly 100 shown in figure 5. Figure 7 shows a simplified representation of the heat exchanger assembly 100 shown in figure 5, with fewer heat exchanger modules 300. Figure 8 shows the arrangement of figure 7 with part of the outer casing 220 removed. Figure 9 shows just the heat exchanger modules 300 and support member 400. In this example, and as best shown in figures 8, 9, a first pair 360 of heat exchanger modules 300 of the plurality of heat exchanger modules 300 may be arranged such that their leading-edge ends 306 are coupled together and their trailing edge ends 308 are spaced apart such that the first pair 360 of heat exchanger modules 300 diverge along the length direction L of the first fluid flow duct 200 to define a first fluid outlet passage 362 therebetween. Hence in this example each heat exchanger module 300 extends diagonally along the support member 400. That is to say, each heat exchanger module 300 extends at an angle to the central axis 212 as it extends along the support member 400. Thus adjacent heat exchanger modules 300 may form a ‘V shape extending along the length L. The flow outlet face 312 of each of the first pair 360 of heat exchanger modules 300 may face one another to define sides of the first fluid outlet passage 362. A second pair 370 of heat exchanger modules 300 of the plurality of heat exchanger modules 300 may be arranged such that their leading-edge ends 306 are coupled together and their trailing edge ends 308 are spaced apart such that the second pair 370 of heat exchanger modules 300 diverge along the length direction L of the first fluid flow duct 200 to define a first fluid outlet passage 362 therebetween. The flow outlet face 312 of each of the second pair 370 of heat exchanger modules 300 may face one another to define sides of a further first fluid outlet passage 362. As best shown in figures 8, 9 one of the heat exchanger modules 300 of the first pair 360 and one of the heat exchanger modules 300 of the second pair 370 may be spaced apart from one another at their leading-edge end 306 and coupled together at their trailing edge end 308, with their flow inlet faces 310 facing one another such that they converge along the length direction L of the first fluid flow duct 200 to define a first fluid inlet passage 364 therebetween. Thus adjacent heat exchanger modules 300 may form a ‘V’ shape extending along the length L. In these examples the heat exchanger modules 300 may be curved along their length in the direction of the central axis 212 and extend radially in a straight line such that heat exchanger modules 300 may define a section of a helix. Adjacent heat exchanger modules 300 may extend in opposite helical directions to one another. That is to say, each heat exchanger module 300 may have a small circumferential component, thus the shape of the heat exchanger module 300 between the first side edge 302 where the heat exchanger module 300 meets the outer casing 220 and the second side edge 304 where the heat exchanger module 300 meets the support member 400 is helical or approximately helical. As such, when the first fluid 202 enters the first fluid inlet passage 364 it cannot flow directly along the duct 200, but must instead flow across and through the heat exchanger module 300 before exiting the duct 200 such that there is heat transfer between the first fluid 202 and the second fluid 330. Hence the first fluid 202 will enter the duct 200 substantially axially, turn to flow generally circumferentially through heat exchange module 300 (e.g. the tube matrix) and then exits substantially axially. As illustrated in figures 5 to 9 the pairs 360, 370 of heat exchanger modules 300 may be provided in series around the support member 400. The pairs 360, 370 of heat exchanger modules 300 may be distributed around the outer surface of the support member 400. The pairs 360, 370 of heat exchanger modules 300 may be spaced around the support member 400. The pairs 360, 370 of heat exchanger modules 300 may be located around the circumference of the support member 400. As illustrated in figures 5 to 9, a plurality of pairs 360, 370 of heat exchanger modules 300 of the plurality of heat exchanger modules 300 may be arranged such that the leading-edge ends 306 of each pair 360, 370 are coupled together and the trailing-edge ends 308 of each pair are spaced apart such that each pair 360, 370 of heat exchanger modules 300 diverge along the length direction L of the first fluid flow duct 200 to define a first fluid outlet passage 362 therebetween. The flow outlet face 312 of each pair 360, 370 of heat exchanger modules 300 face one another to define sides of their respective first fluid outlet passage 362. As illustrated in figures 5 to 9, each heat exchanger module 300 of each pair 360, 370 is spaced apart from an adjacent heat exchanger module 300 (i.e. of the other pair) at their leadingedge end 306 and coupled to the adjacent heat exchanger module 300 at their trailing edge end 308, with their flow inlet faces 310 facing one another such that they converge along the length direction L of the first fluid flow duct 200 to define a first fluid inlet passage 364 therebetween. The plurality of pairs 360, 370 may be provided in series around the support member 400. The plurality of pairs 360, 370 may be distributed around the outer surface of the support member 400. The plurality of pairs 360, 370 may be spaced around the support member 400. The plurality of pairs 360, 370 may be located around the circumference of the support member 400. A second example of a heat exchanger assembly 100 according to the present disclosure is shown in figures 10 to 16. Figure 10 shows an external view of the second example heat exchanger assembly 100. Figure 11 shows the arrangement of figure 10 with part of the outer casing 220 removed. Figure 12 shows the arrangement of figure 11 with further parts of the assembly removed. Figure 13 shows the arrangement of figure 12 with further parts of the outer casing 220 and some divider plates 382 removed. Figure 14 shows an alternative arrangement of the same example shown in figure 12 with parts of the outer casing 220 removed. Figure 15 shows the arrangement of figure 14 with an end cap removed. Figure 16 shows the arrangement of figure 15 with a manifold coupling plate 290 removed. The manifold coupling plate 290 links sub-sections of heat exchange modules 300 together to form a complete heat exchanger module 300. Manifold coupling plates 290 may also provide fluid couplings for the passage of second fluid 330 from one sub-section to another. A third example of a heat exchanger assembly 100 according to the present disclosure is shown in figures 17 to 20. Figure 17 shows an external view of the third example heat exchanger assembly 100. Figure 18 shows the arrangement of figure 17 with the outer casing 220 removed. Figure 19 shows the arrangement of figure 11 with further parts of the outer casing 220 removed. Figures 18, 19 show an example with a middle manifold coupling plate in fluid communication with the heat exchanger modules 300. Figure 20 shows the arrangement shown in figure 19 with the middle manifold plate 290 in place. A fourth example of a heat exchanger assembly 100 according to the present disclosure is shown in figures 21 to 23. Figure 21 shows an external view of the fourth example heat exchanger assembly 100. Figure 22 shows the arrangement of figure 21 with part of the outer casing 220 removed. Figure 23 shows the arrangement of figure 11 with all of the outer casing 220 removed. In each of the examples of figures 10 to 16, figures 17 to 20 and figures 21 to 23 a first pair 360 of heat exchanger modules 300 of the plurality of heat exchanger modules 300 are arranged such that they are spaced apart from one another along their length to define a first fluid flow chamber 380 therebetween. The first pair 360 of heat exchanger modules 300 of the plurality of heat exchanger modules 300 may be arranged such that they are spaced apart from one another by a substantially constant distance along their axial length to define the first fluid flow chamber 380 therebetween. In each of the examples of figures 10 to 16, figures 17 to 20 and figures 21 to 23 a divider plate 382 may be provided between the first pair 360 of heat exchanger modules 300. Each divider plate 382 extends from the leading-edge end 306 of one of the pair 360 of heat exchanger modules 300 to the trailing edge end 308 of the other of the pair 360 of heat exchanger modules 300 to divide / split the first fluid flow chamber 380 into a first sub-chamber 384 and a second flow chamber 386. Each divider plate 382 may extend the full distance between the support member 400 and the outer casing 220. Each divider plate may be solid and / or impermeable to the first fluid 202 such that the divider plate 382 acts a barrier to the first fluid 202, such that the only flow path for the first fluid 202 is through the heat exchanger modules 300. As illustrated in figures 11, 12, 16, one or more of the divider plates 382 may be provided in several sections which are manufactured separately and then assembled. This may be advantageous to make manufacturing and / or assembly easier and / or cheaper. The first sub-chamber 384 extends from the leading-edge end 306 of a heat exchanger module 300 spaced apart from the adjacent heat exchanger module 300 by a divider plate 382 to define the first fluid inlet passage 364. The second sub-chamber 386 thus defines the first fluid outlet passage 362. Hence in each of the examples of figures 10 to 16, figures 17 to 20 and figures 21 to 23, one side of the divider plate 382 faces a flow inlet face 310 of one of the first pair 360 of heat exchanger modules 300 and the other side of the divider plate 382 faces a flow outlet face 312 of the other of the first pair 360 of heat exchanger modules 300. Thus in each of the examples of figures 10 to 16, figures 17 to 20 and figures 21 to 23, the first fluid 202 entering the first sub-chamber 384 (first fluid inlet passage 364) flows between a first divider plate 382 and the heat exchanger module 300 and is thus directed through the heat exchanger module flow inlet face 310, passes through the heat exchange structure 390 (e.g. tube matrix), exits the heat exchanger module flow outlet face 312 into the first fluid outlet passage 362 (i.e. the second sub-chamber 386) and travels between a second divider plate 382 and the heat exchanger module till it exits the flow duct 200. The plurality of heat exchanger modules 300 may be arranged such that they are each spaced apart from one another along their length to define a first fluid flow chamber 380 between each adjacent pair of heat exchanger modules 300. The plurality of heat exchanger modules 300 may be arranged such that they are each spaced apart from one another by a substantially constant distance along their length to define a first fluid flow chamber 380 between each adjacent pair of heat exchanger modules 300. A divider plate 382 may be provided between each pair 360, 370 of adjacent heat exchanger modules 300, each divider plate 382 extending from the leading-edge end 306 of one of the adjacent heat exchanger modules 300 to the trailing edge end 308 of the other heat exchanger module 300 of the pair of adjacent heat exchanger modules 300 to divide the first fluid flow chamber 380 into a first sub-chamber 384 and a second flow chamber 386. Hence a plurality of first fluid flow chambers 380 are defined, spaced apart around the support member 400. Hence a plurality of pairs of first sub-chambers 384 and second flow chambers 386 are provided, the pairs of first sub-chambers 384 and second flow chambers 386 being spaced apart around the support member 400. Each divider plate 382 may face a flow inlet face 310 of one of the adjacent heat exchanger modules 300. Each divider plate 382 may face a flow outlet face 312 of the other of the adjacent heat exchanger modules 300. As shown in the examples of figures 10 to 16, each of the heat exchanger modules 300 may be aligned with the length direction L of the first fluid flow duct 200. In the same examples, since each divider plate 382 extends from the leading-edge end 306 of one of the adjacent heat exchanger modules 300 to the trailing edge end 308 of the other heat exchanger module 300 of the pair of adjacent heat exchanger modules 300, each of the divider plates 382 are provided at an angle to each of the heat exchanger modules 300 along the length direction L of the first fluid flow duct 200. As shown in the examples of figures 10 to 16, the or each heat exchanger module 300 may extend along the length direction L such that their first side edge 302 and second side edge 304 are aligned with the central axis 212. In these examples the or each heat exchanger module 300 curves (i.e. is arcuate) along its width between the first side edge 302 and the second side edge 304. In these examples the divider plates 382 curved along their length in the direction of the central axis 212 and curve (i.e. are arcuate) along their width in between the support member 400 and the outer casing 220. Hence, in examples in which a heat exchange structure 390 comprising a plurality of microtubes is present, the microtubes 340 may curve (i.e. be arcuate) along their length between the first side edge 302 and second side edge 304 of the heat exchanger module 300. Each of the divider plates 382 may curve along their width between the first fluid flow duct 200 and the support member 400 and / or curve along their length between their leading-edge end 306 and their trailing edge end 308. Hence the or each divider plates 382 may be helical or approximately helical. As shown in figures 10 to 16, the or each heat exchanger module 300 may curve along its width between the first side edge 302 and the second side edge 304 and / or curve along its length between the leading-edge end 306 and the trailing edge end 308. As shown in figures 10 to 16, the or each heat exchanger module 300 may “spiral out” along its width between the first side edge 302 and the second side edge 304. As shown in the examples of figures 17 to 20, the or each heat exchanger module 300 may be planar (e.g. flat). In the same example the or each heat exchanger module 300 may extend along the length direction L, be aligned with the central axis 212 and extend radially outwards from support member 400. In these examples the divider plates 382 may be planar. In these examples the divider plates 382 may be curved along their length in the direction of the central axis 212 and extend radially in a straight line that the dividers define a section of a helix. Hence a helical and converging flow path may be defined between each heat exchanger module 300 and a corresponding divider plate 382. That is to say, the first sub-chamber 384 may be provided as a helical and converging flow path defined between each heat exchanger module 300 and divider plate 382, and the second sub-chamber 386 may be provided as a helical and diverging flow path defined between each heat exchanger module 300 and divider plate 382. Hence in both the examples of figures 10 to 16 and figures 17 to 20 each heat exchanger module 300 is ‘straight’ in the axial direction. To ensure that the first fluid 202 flows through the heat exchanger modules 300 in the correct manner, the divider plates 382 are introduced to separate the front of one heat exchanger module 300 from the back of the adjacent heat exchanger module 300. In both the examples of figures 10 to 16 and figures 17 to 20 the divider plates 382 may match the shape of the heat exchanger modules 300, but have a small circumferential component such that the path they trace along the outer casing and support member 400 is helical or approximately helical. Thus the first fluid 202 is forced to turn and flow generally circumferentially through the tube matrix in each heat exchanger module 300 before returning to flow axially to exit the heat exchanger module 300. As shown in the example of figures 10 to 16, the heat exchanger modules 300 may be curved along their radial extent, which may enable an increase in the matrix flow area, a reduction in the total number of tubes, and allow for good management of thermal expansion, which is naturally easier to deal with in curved tubes. As shown in the examples of figures 21 to 23 each of the divider plates 382 may be aligned with the length direction L of the first fluid flow duct 200. In these examples the divider plates 382 may be planar. In the same examples, since each divider plate 382 extends from the leading-edge end 306 of one of the adjacent heat exchanger modules 300 to the trailing edge end 308 of the other heat exchanger module 300 of the pair of adjacent heat exchanger modules 300, each of the heat exchanger modules 300 is provided at an angle to each of the divider plates 382 along the length direction L of the first fluid flow duct 200. Hence each heat exchanger module 300 extends diagonally along the support member 400. That is to say, each heat exchanger module 300 extends at an angle to the central axis 212 as it extends along the support member 400. As shown in the examples of figures 21 to 23, the or each heat exchanger module 300 may be curved along their length in the direction of the central axis 212 and extend radially outwards from the support member 400 in a straight line such that the or each heat exchanger module 300 define a section of a helix. As shown in the examples of figures 21 to 23 the or each divider plate 382 may extend along the length direction L, is aligned with the central axis 212 and extends radially outwards from the support member 400. Hence a helical and converging flow path may be defined between each heat exchanger module 300 and divider plate 382. That is to say, the first sub-chamber 384 may be provided as a helical and converging flow path defined between each heat exchanger module 300 and divider plate 382, and the second sub-chamber 386 may be provided as a helical and diverging flow path defined between each heat exchanger module 300 and divider plate 382. Hence in the examples of figures 21 to 23 the heat exchanger modules 300 extend diagonally and helically, with each heat exchanger module 300 have the same profile along its length as the others, and orientated in the same direction. The divider plates 382 separate the front of each heat exchanger module 300 from the back of the adjacent heat exchanger 300. Hence this example includes diagonal / helical heat exchanger modules 300 with a common orientation. As such, divider plates 382 are required to separate the front of each heat exchanger module 300 from the back of an adjacent heat exchanger 300. As shown in figures 5, 10 to 13, 17, 18, the outer casing 220 may have various features to contain and direct the second fluid 330 flow. For example the outer casing may include radial spokes 230 at the first fluid flow duct flow inlet 204 and / or the first fluid flow outlet 206 configured to block gaps between heat exchanger modules 300 to prevent first fluid 202 air bypassing them, and generally direct the first fluid 202. The radial spokes 230 may also protect the leading edge ends 306 and / or trailing edge ends 308 of the heat exchanger modules 300 from damage (e.g. due to large foreign object debris or mishandling. The radial spokes 230 may also provide structural support to the heat exchanger components. The radial spokes 230 may also define or support conduits (e.g. ducts 500, 502 as described with reference to figures 24 to 32) to transmit second fluid 330 to or from the tube matrix. In some examples, not shown, there may be provided flow vanes at the first fluid flow duct flow inlet 204 and / or the first fluid flow outlet 206 to control the direction and uniformity of flow into the fluid duct 200. Figures 24 to 32 provide different examples of how the heat exchange structure 390 of the or each heat exchanger heat exchanger modules 300 of the examples of the present disclosure may be configured. That is to say, figures 24 to 32 provide different examples of how the plurality of microtubes 340 of the or each heat exchanger heat exchanger modules 300 of the examples of the present disclosure may be configured. As shown in the examples of figures 24 to 26, the leading-edge end 306 of the heat exchanger module 300 may comprise a second fluid flow inlet duct 500 configured to deliver the second fluid 330 to the second fluid flow inlet 320 of the heat exchanger module 300. The trailing edge end 308 of the heat exchanger module 300 may comprise a second fluid flow outlet duct 502 configured to receive the second fluid 330 from the heat exchanger module 300 and deliver it to the second fluid flow outlet 322. The plurality of microtubes 340 may extend from the second fluid flow inlet duct 500 to the second fluid flow outlet duct 502 ofthe heat exchanger module 300. The plurality of microtubes 340 may extend axially from the second fluid flow inlet duct 500 to the second fluid flow outlet duct 502 ofthe heat exchanger module 300. As shown in the examples of figures 24, 25, the second fluid passage 404 in the support member 400 may be configured to deliver the second fluid 330 to the second fluid flow inlet duct 500. That is to say, the second fluid passage 404 in the support member 400 may be configured to deliver the second fluid 330 to the second fluid flow inlet 320 via the second fluid flow inlet duct 500. The support member 400 may define and / or house a second fluid exhaust passage 406 configured to receive the second fluid 330 from the second fluid flow outlet duct 502. That is to say, the support member 400 may define and / or house a second fluid exhaust passage 406 configured to receive the second fluid 330 from the second fluid flow outlet 322 via the second fluid flow outlet duct 502. As shown in the example of figure 26, the second fluid flow inlet duct 500 may extend through the first fluid flow duct 200, and the second fluid flow outlet duct 502 may extend through the first fluid flow duct 200. As shown in the examples of figures 27 to 30, the plurality of microtubes 340 may extend from the first side edge 302 of the heat exchanger module 300 to the second side edge 304 of the heat exchanger module 300. That is to say, as shown in the examples of figures 27 to 30, the plurality of microtubes 340 may extend radially from the first side edge 302 ofthe heat exchanger module 300 to the second side edge 304 ofthe heat exchanger module 300. The second fluid passage 404 in the support member 400 may be configured to deliver the second fluid 330 to the second fluid flow inlet 320 ofthe heat exchanger module 300. As shown in the example of figure 27, the first side edge 302 ofthe heat exchanger module 300 may comprise a second fluid flow outlet duct 502 in fluid communication with the second fluid flow outlet 322, and the second fluid flow outlet duct 502 may extend through the first fluid flow duct 200. As shown in the example of figure 28 the first side edge 302 and leading-edge end 306 of the heat exchanger module 300 may comprise a second fluid flow outlet duct 502 in fluid communication with the second fluid flow outlet 322, and the second fluid flow outlet duct 502 may terminate at the support member 400. As shown in the example of figure 29, the first side edge 302 and trailing edge end 308 of the heat exchanger module 300 may comprise a second fluid flow outlet duct 502 in fluid communication with the second fluid flow outlet 322, and the second fluid flow outlet duct 502 may deliver the second fluid 330 to a second fluid exhaust passage 406 provided in the support member 400. As shown in the example of figure 30 the first section 520 of the first side edge 302 may comprise a second fluid flow outlet duct 502 which is configured to receive the second fluid 330 from a first section 520 of microtubes 340 and configured to deliver the second fluid 330 to a second section 522 of microtubes 540 which are configured to deliver the second fluid 330 to a second fluid exhaust passage 406 provided in the support member 400. As shown in the examples of figures 31, 32 the second fluid flow inlet 320 and the second fluid flow outlet 322 of the heat exchanger module 300 may be provided at the first side edge 302. The plurality of microtubes 340 may first extend from the first side edge 302 to the second side edge 304 and then return to the first side edge 302 in repeating pattern which extends along the extent of the first side edge 302 and second side edge 304. In further examples, the direction of flow between the leading edge-end 306 and trailing edge-end 308 as described with reference to figures 24 to 32 may be reversed. That is to say, while the direction of flow between the leading edge-end 306 and trailing edge-end 308 may be arranged to flow in the opposite direction to that shown and described with reference to figures 24 to 32. In each of the examples, the heat exchanger assembly 100 may comprise a ring supply manifold in fluid communication with, and to supply, the second fluid flow inlet duct 500 and / or a second fluid ring return manifold in fluid communication with, and to receive the second fluid from the second fluid outlet duct 502. The or each ring supply manifold may be in fluid communication with each of the second fluid flow inlet duct 500 and second fluid flow outlet duct 504. Hence there is provided a heat exchanger assembly which provides a very large flow area and a very low axial flow blockage compared to examples of the related art. This is enabled by the orientation of the heat exchanger module(s) 300 in the flow duct 200, which leaves the first fluid flow inlet 204 and the first fluid flow outlet 206 (where all the air is flowing axially) essentially “open” (i.e. unobstructed). This also assists with reducing aerodynamic drag in examples where relevant (for example in a moving vehicle). The very large flow area is defined by the first heat exchanger module flow inlet face 310. For example, the flow area may be defined by the heat exchanger matrix constructed of the plurality of layers 342 of microtubes 340. The arrangement of the heat exchanger modules 300 between a first flow duct 200 and a support member 400, and (in examples in which a plurality or several heat exchanger modules 300 are provided) spaced around the support member 400, enables a large heat transfer area to be fitted into a small volume, with each heat exchanger at least in part defining the flow path therethrough. This enables a compact and / or efficient heat exchanger assembly compared to examples of the related art. The apparatus of the present disclosure is configured to provide a low frontal / flow area heat exchanger by virtue of the axial blockage at inlet and outlet being reduced to just the leading edges of the heat exchanger modules 300 (which may be very thin, due to the microtube construction), the support member 400 (which is comparatively small), and a minimal amount of additional hardware necessary to mount and support the other components. In addition, the flow area (i.e. heat transfer area) through the tube matrix is very large. The various configurations of second fluid flow paths through the heat exchanger 300 described with reference to figures 24 to 32 provide a variety of advantages for different applications and build style. For example, where the microtubes flow axially, these arrangements may be easier to construct. Where the microtubes flow radially, these arrangements may provide greater heat transfer or reduced pressure drop for the second fluid. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 A heat exchanger assembly (100) comprising:a first fluid flow duct (200) for the passage of a first fluid (202) therethrough, wherein the first fluid flow duct (200) defines a first fluid flow inlet (204) and a first fluid flow outlet (206) spaced apart from one another along a length direction (L) of the first fluid flow duct (200);a first heat exchanger module (300) having a leading-edge end (306) and a trailing edge end (308), the leading-edge end (306) and the trailing edge end (308) spaced apart from one another along the length direction (L) of the first fluid flow duct (200);the first heat exchanger module (300) having a flow inlet face (310) and a flow outlet face (312) which extend between the leading-edge end (306) and the trailing edge end (308) along the length direction (L) of the first fluid flow duct (200);wherein the first fluid flow duct flow inlet (204), the first heat exchanger module flow inlet face (310), the first heat exchanger module flow outlet face (312), and the first fluid flow outlet (206) are provided in series along the length direction (L) of the first fluid flow duct (200) to define a first fluid flow path (210) through the first fluid flow duct (200);the heat exchanger assembly (100) further comprising a support member (400) located within, and spaced apart from, the first fluid flow duct (200) such that the support member (400) defines at least part of the first fluid flow path (210); andthe first heat exchanger module (300) extends across the first fluid flow duct (200) from a first side edge (302) located on the first fluid flow duct (200) to a second side edge (304) located on the support member (400).2 A heat exchanger assembly (100) as claimed in claim 1 wherein the first heat exchanger module (300) comprises:a second fluid flow inlet (320) for receiving a second fluid (330) from a heat sink / source (332); anda second fluid flow outlet (322) for delivering the second fluid (330) to the heat sink / source (332);wherein the second fluid (330) is fluidly isolated from, and different to, the first fluid (202).3 A heat exchanger assembly (100) as claimed in claim 1 or claim 2 comprising a plurality of heat exchanger modules (300), the first heat exchanger module (300) being one of the plurality of heat exchanger modules (300);each heat exchanger module (300) having a leading-edge end (306) and a trailing edge end (308), each leading-edge end (306) spaced apart from its respective trailing edge end (308) along the length direction (L) of the first fluid flow duct (200);each heat exchanger module (300) having a flow inlet face (310) and a flow outlet face (312) which extend between the leading-edge end (306) and a trailing edge end (308) along the length direction (L) of the first fluid flow duct (200);wherein the first fluid flow duct flow inlet (204), each heat exchanger module flow inlet face (310), each first heat exchanger module flow outlet face (312), and the first fluid flow outlet (206) are provided in series along the length direction (L) of the first fluid flow duct (200) to define the first fluid flow path (210) through the first fluid flow duct (200); andeach heat exchanger module (300) extends across the first fluid flow duct (200) from a first side edge (302) located on the first fluid flow duct (200) to a second side edge (304) located on the support member (400).4 A heat exchanger assembly (100) as claimed in claim 3 wherein each heat exchanger module (300) comprises:a second fluid flow inlet (320) for receiving a second fluid (330) from a heat sink / source (332); anda second fluid flow outlet (322) for delivering the second fluid (330) to a heat sink / source (332).5 A heat exchanger assembly (100) as claimed in claim 2 or claim 4 wherein:the support member (400) defines and / or houses a second fluid passage (404);the second fluid flow inlet (320) is in fluid communication with the heat sink / source (332) via the second fluid passage (404); and / orthe second fluid flow outlet (322) is in fluid communication with the heat sink / source (332) via the second fluid passage (404).6 A heat exchanger assembly (100) as claimed in claim 2 or claim 4 wherein a plurality of microtubes (340) provide fluid communication between the second fluid flow inlet (320) and the second fluid flow outlet (322), each microtube (340) defining a second fluid flow path (350); anda plurality of layers (342) of microtubes (340) define the flow path extending between the first heat exchanger module flow inlet face (310) and the first heat exchanger module flow outlet face (312).7 A heat exchanger assembly (100) as claimed in any one of claims 3 to 6 wherein a first pair (360) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) are arranged such that:their leading-edge ends (306) are coupled together and their trailing edge ends (308) are spaced apart such that the first pair (360) of heat exchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween; andthe flow outlet face (312) of each of the first pair (360) of heat exchanger modules (300) face one another to define sides of the first fluid outlet passage (362).8 A heat exchanger assembly (100) as claimed in claim 7 wherein a second pair (370) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) are arranged such that:their leading-edge ends (306) are coupled together and their trailing edge ends (308) are spaced apart such that the second pair (370) of heat exchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween;the flow outlet face (312) of each of the second pair (370) of heat exchanger modules (300) face one another to define sides of the first fluid outlet passage (362); andone of the heat exchanger modules (300) of the first pair (360) and one of the heat exchanger modules (300) of the second pair (370) are spaced apart from one another at their leading-edge end (306) and coupled together at theirtrailing edge end (308), with their flow inlet faces (310) facing one another such that they converge along the length direction (L) of the first fluid flow duct (200) to define a first fluid inlet passage (364) therebetween.9 A heat exchanger assembly (100) as claimed in claim 8 wherein a plurality of pairs (360, 370) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) are arranged such that:the leading-edge ends (306) of each pair (360, 370) are coupled together and the trailing-edge ends (308) of each pair are spaced apart such that each pair (360, 370) of heatexchanger modules (300) diverge along the length direction (L) of the first fluid flow duct (200) to define a first fluid outlet passage (362) therebetween;the flow outlet face (312) of each pair (360, 370) of heat exchanger modules (300) face one another to define sides of their respective first fluid outlet passage (362); andeach heat exchanger module (300) of each pair (360, 370) is spaced apart from an adjacent heat exchanger module (300) at their leading-edge end (306) and coupled to the adjacent heat exchanger module (300) at their trailing edge end (308), with their flow inlet faces (310) facing one another such that they converge along the length direction (L) of the first fluid flow duct (200) to define a first fluid inlet passage (364) therebetween;the pairs (360, 370) being provided in series around the support member (400).10 A heat exchanger assembly (100) as claimed in any one of claims 3 to 6 wherein a first pair (360) of heat exchanger modules (300) of the plurality of heat exchanger modules (300) are arranged such that they are spaced apart from one another along their length to define a first fluid flow chamber (380) therebetween; anda divider plate (382) is provided between the first pair (360) of heat exchanger modules (300) which extends from the leading-edge end (306) of one of the pair (360) of heat exchanger modules (300) to the trailing edge end (308) of the other of the pair (360) of heat exchanger modules (300) to divide the first fluid flow chamber (380) into a first subchamber (384) and a second flow chamber (386);the divider plate (382) facing a flow inlet face (310) of one of the first pair (360) of heat exchanger modules (300) and facing a flow outlet face (312) of the other of the first pair (360) of heat exchanger modules (300).11 A heat exchanger assembly (100) as claimed in claim 10 wherein the plurality of heat exchanger modules (300) are arranged such that they are spaced apart from one another along their length to define a first fluid flow chamber (380) therebetween; anda divider plate (382) is provided between each pair (360, 370) of adjacent heat exchanger modules (300), each divider plate (382) extending from the leading-edge end (306) of one of the adjacent heat exchanger modules (300) to the trailing edge end (308) of the other heat exchanger module (300) of the pair of adjacent heat exchanger modules (300) to divide the first fluid flow chamber (380) into a first sub-chamber (384) and a second flow chamber (386);each divider plate (382) facing a flow inlet face (310) of one of the adjacent heat exchanger modules (300) and facing a flow outlet face (312) of the other of the adjacent heat exchanger modules (300).12 A heat exchanger assembly (100) as claimed in claim 10 or claim 11 wherein each of the heat exchanger modules (300) are aligned with the length direction (L) of the first fluid flow duct (200).13 A heat exchanger assembly (100) as claimed in claim 10 or claim 11 wherein each of the divider plates (382) are aligned with the length direction (L) of the first fluid flow duct (200).14 A heat exchanger assembly (100) as claimed 13 wherein each of the divider plates (382) are planar.15 A heat exchanger assembly (100) as claimed in claim 12 wherein each of the divider plates curve along their width between the first fluid flow duct (200) and the support member (400) and / or curve along their length between their leading-edge end (306) and theirtrailing edge end (308).16 A heat exchanger assembly (100) as claimed in any one of claims 1 to 15 wherein the or each heat exchanger module (300) is planar.17 A heat exchanger assembly (100) as claimed in any one of claims 1 to 15 wherein the or each heat exchanger module (300) curves along its width between the first side edge (302) and the second side edge (304) and / or curves along its length between the leading-edge end (306) and the trailing edge end (308).18 A heat exchanger assembly (100) as claimed in claim 6 and any one of claims 7 to 17 when dependent on claim 6 wherein:the leading-edge end (306) of the heat exchanger module (300) comprises a second fluid flow inlet duct (500) configured to deliver the second fluid (330) to the second fluid flow inlet (320) of the heat exchanger module (300);the trailing edge end (308) of the heat exchanger module (300) comprises a second fluid flow outlet duct (502) configured to receive the second fluid (330) from the second fluid flow outlet (322) of the heat exchanger module (300); andthe plurality of microtubes (340) extend from the second fluid flow inlet duct (500) to the second fluid flow outlet duct (502) of the heat exchanger module (300).19 A heat exchanger assembly (100) as claimed in claim 18 wherein:a second fluid passage (404) in the support member (400) is configured to deliver the second fluid (330) to the second fluid flow inlet duct (500); andthe support member (400) defines and / or houses a second fluid exhaust passage (406) configured to receive the second fluid (330) from the second fluid flow outlet duct (502).20 A heat exchanger assembly (100) as claimed in claim 18 wherein:the second fluid flow inlet duct (500) extends through the first fluid flow duct (200); andthe second fluid flow outlet duct (502) extends through the first fluid flow duct (200).21 A heat exchanger assembly (100) as claimed in claim 6 and any one of claims 7 to 17 when dependent on claim 6 wherein:the plurality of microtubes (340) extend from the first side edge (302) of the heat exchanger module (300) to the second side edge (304) of the heat exchanger module (300); anda second fluid passage (404) in the support member (400) is configured to deliver the second fluid (330) to the second fluid flow inlet (320) of the heat exchanger module (300).22 A heat exchanger assembly (100) as claimed in claim 21 wherein:the first side edge (302) of the heat exchanger module (300) comprises a second fluid flow outlet duct (502) in fluid communication with the second fluid flow outlet (322), and the second fluid flow outlet duct (502) extends through the first fluid flow duct (200).23 A heat exchanger assembly (100) as claimed in claim 21 wherein:the first side edge (302) and leading-edge end (306) of the heat exchanger module (300) comprises a second fluid flow outlet duct (502) in fluid communication with the second fluidflow outlet (322), and the second fluid flow outlet duct (502) terminates at the support member (400).24 A heat exchanger assembly (100) as claimed in claim 21 wherein:the first side edge (302) and trailing edge end (308) of the heat exchanger module (300) comprise a second fluid flow outlet duct (502) in fluid communication with the second fluid flow outlet (322), and the second fluid flow outlet duct (502) delivers the second fluid (330) to a second fluid exhaust passage (406) provided in the support member (400).25 A heat exchanger assembly (100) as claimed in claim 21 wherein:a first section (520) of the first side edge (302) comprises a second fluid flow outlet duct (502) which is configured to receive the second fluid (330) from a first section (520) of microtubes (340) and configured to deliverthe second fluid (330) to a second section (522) of microtubes (540) which are configured to deliver the second fluid (330) to a second fluid exhaust passage (406) via the second fluid flow outlet (322), the second fluid exhaust passage (406) being provided in the support member (400).26 A heat exchanger assembly (100) as claimed in claim 6 and any one of claims 7 to 17 when dependent on claim 6 wherein:the second fluid flow inlet (320) and the second fluid flow outlet (322) of the heat exchanger module (300) are provided at the first side edge (302);the plurality of microtubes (340) first extend from the first side edge (302) to the second side edge (304) and then return to the first side edge (302) in repeating pattern which extends along the extent of the first side edge (302) and second side edge (304).27 A heat exchanger assembly (100) as claimed in any one of claims 1 to 26 wherein the first fluid flow duct (200) is cylindrical, the length (L) of the first fluid flow duct (200) being greater than its diameter (D).28 A heat exchanger assembly (100) as claimed in any one of claim 1 to 27 wherein the first fluid flow duct (200) and the support member (400) are coaxial and / or concentric.29 A heat exchanger assembly (100) as claimed claim 28 wherein the or each heat exchanger module (300) extends radially from the support member (400) to the first fluid flow duct (200).30 A system (600) comprising a heat exchanger assembly (100) as claimed in any one of claims 1 to 29 wherein the system (600) is provided as a land, sea or air vehicle.31 A system (600) as claimed in claim 30 comprising a first fluid flow intake (602) and an first fluid flow outlet (610), wherein the system first fluid flow intake (602), heat exchanger assembly first fluid flow inlet (204), heat exchanger assembly first fluid flow outlet (206) and system first fluid flow outlet (610) are provided in series to define a first fluid flow path (606).32 A system (600) as claimed in claim 31 further comprising:a first fluid inlet duct (604) extending from the system fluid flow intake (602) to the heat exchanger assembly first fluid flow inlet (204);a first fluid outlet duct (608) extending from the heat exchanger assembly first fluid flow outlet (206) to the system first fluid flow outlet (610);the system first fluid inlet duct (604), heat exchanger assembly (100) and system first fluid outlet duct (608) being provided in series to define the first fluid flow path (606).

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