Patent Description:
In the aviation engineering, heat exchangers have a fundamental role in the thermal management of various components in the aircraft to ensure that they operate within their designs operating ranges.

Heat exchangers may be used to increase or decrease the temperature of fuel during a flight to increase the efficiency of fuel use within the aircraft engines. Such heat exchangers are known in the art. For example, <CIT> describes a plate fin heat exchanger having a plurality of finned cold layers configured to conduct a first fluid, and a plurality of finned warm layers configured to conduct a second fluid. A first portion of fins of at least one finned warm layer of the plurality of finned warm layers includes a plurality of aligned peaks and valleys defining a wave configuration for each fin of the first portion of fins.

The design process of next generation aerospace heat exchangers faces an increased heat rejection demand. At moderate flight speeds, heat from the systems of aviation engines, lubricants, and different equipment and optional energy systems will often be rejected into air. At relatively high-speeds, heat from these components is often rejected into another heat sink, such as the fuel of the aircraft.

The design of heat exchangers in the aircraft should comply with the constructional requirements of the aircraft, e.g. installation volume, pressure drop, heat duty. Further, many aircraft have strict weight and size requirements and it is a challenge to provide a relatively lightweight and space efficient heat exchanger that is capable of providing the required cooling to the components of the aircraft. Furthermore, traditional heat exchangers that are exposed to incoming air may also have a negative effect on the amount of drag on the aircraft.

The development of new kinds of heat exchangers is ever in progress, both for seeking to reduce the volume of the heat exchanger and to enhance the performances in terms of pressure drop and heat transfer capacity.

The heat exchanger of this disclosure seeks to address some of these above-mentioned problems.

According to one example, there is provided a heat exchanger comprising:
a housing comprising: an inlet at a proximal end for receiving a first fluid; and an outlet, downstream of the inlet at the distal end of the housing, through which the fluid is configured to exit the housing; and a plurality of heat exchanger cores within the housing, wherein the plurality of heat exchanger cores meet at a junction and diverge [from each other] towards one of the inlet or the outlet of the housing, wherein the plurality of heat exchanger cores comprise one or more first flow paths through which the first fluid can pass through the heat exchanger cores, in use.

Heat Exchangers are traditionally the biggest components within a thermal Management system. The provision of the diverging cores results in a relatively small and lightweight installation volume compared to other installations whilst simultaneously having same/better thermal performance than inclined or "traditional" cuboid installation. Further the relatively low first fluid pressure losses minimises the overall drag, whilst still delivering the cooling first fluid without the need for motivators.

The provision of a heat exchanger with diverging heat exchanger cores reduces the pressure drop of a first fluid flowing through the heat exchanger, whilst still providing a high level of heat transfer. Reducing the pressure drop results in a reduction of drag on the aircraft. The heat exchanger may be located within ductwork within an aircraft (with a vent to the air) or alternative coupled to an outer skin of the aircraft.

The housing may comprise a substantially square-shaped cross section. In other words, the housing may be substantially cuboid shaped with an opening at a proximal end and an opening at the distal end.

A length of the heat exchanger is approximately four times the length of a width of the heat exchanger. The length of the heat exchanger is the distance between the distal end and proximal end of the heat exchanger along the longitudinal axis of the heat exchanger. The width of the heat exchanger is the distance between walls of the housing in a direction perpendicular to the longitudinal axis of the housing.

In one example, each of the plurality of heat exchanger cores comprises a core inlet for receiving a second fluid and a core outlet through which the second flow is configured to exit the heat exchanger core.

In one example, the core inlet of the heat exchanger core is arranged towards the distal end of the housing. In another example, the core inlet of the heat exchanger is arranged towards the proximal end of the housing. In one example, the core inlet of the heat exchanger is arranged at the junction of the heat exchanger cores.

In one example, the outlet of the heat exchanger core is arranged at the junction of the heat exchanger cores. In other examples, the core outlet of the heat exchanger is arranged towards the proximal end of the housing. In one example, the core outlet of the heat exchanger is arranged at the junction of the heat exchanger cores.

The heat exchanger according to any one of the preceding claims, wherein the heat exchanger cores diverge from each other at an angle of between <NUM> to <NUM> degrees.

In one example, the heat exchanger core comprises a finned tube arrangement. In another example, the heat exchanger core comprises a plate-fin arrangement. The heat exchanger core may comprise a plurality of layers.

In one example, the heat exchanger comprises one or more aerofoils configured to guide the flow of the first fluid.

In one example, the heat exchanger cores diverge from each other towards the inlet of the housing. In another example, the heat exchanger cores diverge from each other towards the outlet of the housing.

In one example, the weight of the heat exchanger is between <NUM> to <NUM>. This is compared with a weight of <NUM> to <NUM> for a traditional heat exchanger with a similar heat transfer performance. A heat exchanger with an inclined heat exchanger core that achieves a similar heat transfer performance would weigh approximately <NUM> to <NUM>.

In one example, the plurality of heat exchanger cores comprises two heat exchanger cores.

According to another example, there is provided an aircraft comprising the heat exchanger as described above.

According to another example, there is provided a heat exchanger comprising: a housing comprising: an inlet at a proximal end for receiving a first fluid; and an outlet, downstream of the inlet at the distal end of the housing, through which the fluid is configured to exit the housing; and a plurality of heat exchanger cores within the housing, wherein the plurality of heat exchanger cores meet at a junction and diverge [from each other] towards one of the inlet or the outlet of the housing, wherein the plurality of heat exchanger cores comprises a plate fin arrangement; and, wherein the plurality of heat exchanger cores comprise one or more first flow paths through which the first fluid can pass through the heat exchanger cores, in use.

In one example, the heat exchanger core is arranged in a counterflow arrangement with respect to the first fluid.

In one example, the outlet of the heat exchanger core is arranged at the junction of the heat exchanger cores. In other examples, the core outlet of the heat exchanger is arranged towards the proximal end of the housing. In one example, the core outlet of the heat exchanger is arranged at the junction of the heat exchanger cores. In one example, the outlets of the plurality of heat exchanger cores may exit the housing through a single aperture.

The heat exchanger cores may diverge from each other at an angle of between <NUM> to <NUM> degrees.

The heat exchanger core may comprise a plurality of layers.

It will be appreciated that features described in relation to one aspect of the present invention can be incorporated into other aspects of the present invention. For example, an apparatus of the invention can incorporate any of the features described in this disclosure with reference to a method, and vice versa. Moreover, additional embodiments and aspects will be apparent from the following description, drawings, and claims. As can be appreciated from the foregoing and following description, each and every feature described herein, and each and every combination of two or more of such features, and each and every combination of one or more values defining a range, are included within the present disclosure provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features or any value(s) defining a range may be specifically excluded from any embodiment of the present disclosure.

<FIG> shows an example of an aircraft <NUM> having fuselage <NUM>. Aircraft <NUM> are well-known in the art and further details of the aircraft have not been provided here. In one example, the aircraft comprises a high-altitude long endurance (HALE) unmanned aircraft. HALE aircraft typically have long wingspans and low drag to improve their ability to operate efficiently for weeks or months at altitudes in excess of <NUM>. In some examples, HALE aircraft include one or more payloads comprising electronic components, such as sensors that require thermal management.

<FIG> shows an example of a housing <NUM> of a heat exchanger. The housing <NUM> comprises walls <NUM> configured to provide an enclosure to house a plurality of heat exchanger cores, which will be discussed in more detail below. The enclosure may be open at opposite ends, as will be discussed in more detail below.

In this example, the heat exchanger housing <NUM> comprises an inlet <NUM> and an outlet <NUM> or exit. The inlet <NUM> is configured to receive a first fluid, such as on- coming air, that may be used as the coolant within the heat exchanger. The outlet <NUM> is configured to allow the first fluid to exit the heat exchanger after it has passed through the heat exchanger. The inlet <NUM> of the heat exchanger housing <NUM> is also the inlet of the heat exchanger. The outlet <NUM> of the heat exchanger is also the outlet of the heat exchanger.

In the example of <FIG>, the housing <NUM> is a cuboid with open, opposite ends defining the inlet <NUM> and the outlet <NUM> respectively. The housing <NUM> may extend along and define a longitudinal axis A-A. In the example of <FIG>, the cross-section of the housing <NUM>, taken perpendicular to the longitudinal axis A-A, would be square-shaped. In other examples, the housing <NUM> may be cylindrical or have other shapes that extend along a longitudinal axis A-A. For example, the housing <NUM> of the heat exchanger may be a circular duct.

The housing <NUM> is shaped so as to be relatively compact, whilst still providing sufficient space for the heat exchanger to be effective. In one example, the housing <NUM> has a length along the longitudinal axis, A-A, of between <NUM> and <NUM>, more preferably <NUM> to <NUM>, more preferably <NUM>.

The width and height of the housing <NUM>, e.g. the dimensions perpendicular to the longitudinal axis A-A, may be between <NUM> and <NUM>, more preferably <NUM>. The length of the housing <NUM> may be approximately four times larger the width/height of the housing <NUM>.

In one example, the housing walls <NUM> have one or more apertures (not shown) for receiving a second fluid, as will be discussed in more detail below.

<FIG> shows an example of a traditional cuboid arrangement of a heat exchanger that is not within the scope of this invention. In this example, the heat exchanger comprises a core <NUM> formed of alternating layers 112a, 112b. The alternating layers comprise alternating layers of first fluid paths 112a and second fluid paths 112b.

In this example, a first fluid flows through the first fluid paths 112a and a second fluid flows through the second fluid paths 112b. The first fluid and second fluid are configured to enter the heat exchanger at different temperatures such that heat is exchanged between the first fluid and the second fluid.

The first fluid enters the core <NUM> in a first direction as indicated by the first arrow B, which in this example is in the direction of the longitudinal axis of the core <NUM>. The first fluid then travels through the core <NUM> and exits the core as shown by the arrow C. The second fluid enters the core <NUM> in a second direction, which in this example is perpendicular to the longitudinal axis of the core <NUM>, as shown by arrow D. The second fluid exits the core as indicated by arrow E.

In this example, the first fluid is blocked off from travelling through the second fluid paths 112b and the second fluid is blocked off from travelling through the first fluid paths 112a.

The blockage of the first fluid flow path using the traditional cuboid installation results in a large pressure drop in the first fluid flow as it enters the heat exchanger. This pressure drop then causes increased drag of the overall drag and might require flow motivators. In addition, this installation results in small frontal area for the first fluid flow path, requiring a fin structure and thus resulting in high installation volume and weight. In other words, the traditional cuboid installation shown in <FIG> is undesirable as it has many drawbacks.

<FIG> shows a heat exchanger <NUM> according to the present invention. In this example, the heat exchanger <NUM> comprises the housing <NUM> as shown in <FIG>. For clarity, the housing is shown as transparent in <FIG> so the elements within the housing <NUM> are visible.

As with <FIG>, the housing <NUM> has an inlet <NUM> for receiving the first fluid and an outlet <NUM>, downstream of the inlet <NUM>, through which the first fluid is configured to exit the housing <NUM>. In one example, the inlet <NUM> of the housing <NUM> is arranged at a proximal end of the housing <NUM> and the outlet <NUM> is arranged at a distal end of the housing <NUM>. In another example, the inlet <NUM> is arranged at the distal end of the housing <NUM> and the outlet is arranged at the proximal end of the housing <NUM>. For clarity, the longitudinal axis A-A has not been overlaid on the <FIG>, but it is shown in <FIG>.

In use, the first fluid is configured to flow from the inlet <NUM> to the outlet <NUM> within the housing <NUM>.

The heat exchanger <NUM> comprises a plurality of heat exchanger cores <NUM>. In this example, the heat exchanger comprises two heat exchanger cores <NUM>.

The heat exchanger cores <NUM> are arranged between the inlet <NUM> and the outlet <NUM> of the housing <NUM> of the heat exchanger <NUM>. That is to say that the first fluid must flow through at least one of the heat exchanger cores <NUM> when travelling from the inlet <NUM> to the outlet <NUM> of the heat exchanger <NUM>.

The heat exchanger cores <NUM> comprises a first fluid path, through which the first fluid can travel. The heat exchanger cores <NUM> also comprise a second fluid path through which a second fluid can travel. The first fluid path and the second fluid path are isolated from each other to prevent mixing of the first fluid and the second fluid. For example, the second fluid may travel within pipes of the heat exchanger core <NUM> whilst the first fluid is configured to flow in a path around the pipes of the heat exchanger core <NUM>.

The heat exchanger cores are angled with respect to the longitudinal axis A-A of the housing <NUM>. Put another way, the heat exchanger cores <NUM> are not parallel with the longitudinal axis A-A of the housing <NUM>.

In the example shown in <FIG>, the heat exchanger cores <NUM> meet or join at a junction <NUM> within the housing <NUM> of the heat exchanger <NUM>. In this example, the heat exchanger cores <NUM> diverge from the junction <NUM> towards the outlet <NUM> of the housing <NUM> of the heat exchanger <NUM>. That is to say that the distance between the heat exchanger cores <NUM> increases from the junction <NUM> towards the outlet <NUM>.

In <FIG>, the heat exchanger <NUM> comprises two heat exchanger cores <NUM>, but more than two heat exchanger cores <NUM> may be used in practice.

The heat exchanger core <NUM> comprises a core inlet <NUM> and a core outlet <NUM>. The core inlet <NUM> is configured to receive a second fluid. The second fluid is configured to leave the heat exchanger core <NUM> through the core outlet <NUM>.

In <FIG>, the wall <NUM> of the housing <NUM> comprises an aperture through which the second fluid can enter into the core inlet <NUM>. In this arrangement, the second fluid would still be isolated from the first fluid as the second fluid would enter directly into a conduit or pipe of the heat exchanger core <NUM> that is isolated from the first fluid.

An additional aperture may be present in the walls <NUM> of the housing <NUM> for the core outlet <NUM> to allow the second fluid to exit the heat exchanger <NUM>.

In the example shown in <FIG>, the core inlets <NUM> are arranged perpendicular to the longitudinal axis A-A of the housing <NUM> of the heat exchanger <NUM>, but other arrangements are possible. The core inlets <NUM> may be arranged towards or adjacent to the inlet <NUM> or outlet <NUM> of the housing <NUM>. In the example shown in <FIG>, the core inlets are shown towards or adjacent to the outlet <NUM> or distal end of the housing <NUM>, but in other arrangements they may be located towards or adjacent to the inlet <NUM> or proximal end of the housing <NUM>. In both examples, the heat exchanger cores <NUM> still diverge from the junction <NUM> towards the inlet <NUM> or the outlet <NUM> of the housing <NUM>.

The core outlet <NUM> may be arranged at or adjacent to the junction <NUM>. The core outlet <NUM> may be arranged to be perpendicular to the longitudinal axis A-A of the housing <NUM>. In one example, the core outlet <NUM> is configured to be perpendicular to the core inlets <NUM>. In other examples, the core inlets <NUM> and core outlet <NUM> may be reversed from those shown in <FIG>. In other words, the second fluid may enter the heat exchanger core <NUM> at the core inlet <NUM>, which is located at or approximate to the junction <NUM> and the second fluid then travels through the heat exchanger core <NUM> towards the core outlet <NUM>, which may be located at or towards the inlet <NUM> or outlet <NUM> of the housing <NUM> (e.g. a counterflow arrangement with respect to the first fluid).

As shown in <FIG>, the core inlets <NUM> of each of the heat exchanger cores <NUM> may be opposite to each other. That is to say that they are arranged on the opposite sides of the housing <NUM> relative to each other. The core outlets <NUM> of the heat exchanger cores <NUM> are arranged adjacent to each other. In one example where the respective core outlets <NUM> of the heat exchanger cores <NUM> are arranged adjacent to each other, both outlets <NUM> may exit the housing <NUM> through a single aperture. In this way, apertures into the housing <NUM> are minimised. This makes the heat exchanger <NUM> simpler to manufacture.

In <FIG>, the first fluid flow enters the heat exchanger <NUM> via the inlet <NUM> in the direction represented by arrow F, i.e. substantially parallel to the longitudinal axis A-A of the housing <NUM>. The first fluid then passes through one or more first flow paths of the heat exchanger cores <NUM> before exiting the housing <NUM> at the outlet <NUM>. The first fluid flow exits the heat exchanger <NUM> in the direction indicated by arrow G in <FIG>.

In <FIG>, a second fluid enters the heat exchanger <NUM> via core inlets <NUM>. The second fluid may enter the heat exchange cores <NUM> in the direction indicated by arrows H in <FIG>.

The second fluid then travels within the heat exchanger core <NUM> and exits the heat exchanger core <NUM> at the core outlet <NUM>. In <FIG>, the second fluid exits the heat exchanger cores <NUM> in the direction indicated by arrow I in <FIG>.

One or more headers (not shown) may be present at the core inlets <NUM> and/or core outlets <NUM>.

In <FIG>, the core inlets <NUM> are shown substantially at or adjacent to the outlet <NUM> of the housing <NUM>. In other words, the core inlets <NUM> may be located at or adjacent to the distal end of the housing <NUM>.

However, in other examples, there may be a gap between the core inlet <NUM> and the distal end of the housing <NUM>.

<FIG> shows a cross-sectional view of the heat exchanger <NUM>. As shown in <FIG>, the heat exchanger cores <NUM> may have the same shape but are handed about the longitudinal axis A-A of the housing.

<FIG> also shows a plurality of flow guide vanes <NUM> within the heat exchanger <NUM>. The flow guide vanes <NUM> may extend the full height of the heat exchanger <NUM>.

The purpose of the flow guide <NUM> vanes to is guide the first fluid to flow through the heat exchanger cores <NUM> at an optimum angle, ensuring even mass flow distribution across the frontal area of the heat exchanger core.

The junction <NUM> at which the heat exchanger cores <NUM> meet may be on the longitudinal axis A-A of the housing. That is to say that the junction may be on a central line, when viewed from above, of the housing <NUM>.

The junction <NUM> may be spaced from the inlet <NUM> of the housing <NUM>. In one example, the junction <NUM> spaced at approximately half the width of the housing <NUM> from the inlet.

The heat exchanger cores <NUM> may be shaped such that the inlet <NUM> is arranged at an approximate <NUM>-degree angle to the longitudinal axis A-A of the housing <NUM>. The heat exchanger cores <NUM> has internal length K, which represents the length of the inside portion of the heat exchanger core <NUM>, e.g. the boundary of the heat exchanger core <NUM> that faces the other heat exchanger core. The heat exchanger core <NUM> also has an external length L, which represents the length of the outside portion of the heat exchanger core <NUM>, e.g. the boundary of the heat exchanger core <NUM> that faces the wall <NUM> of the housing <NUM>.

<FIG> also shows a width J, which is the dimension perpendicular to the longitudinal axis A-A at the core inlet <NUM>.

In the example shown in <FIG>, the heat exchanger cores <NUM> are configured to diverge at an angle denoted by α. A key design constraint of the heat exchanger <NUM> is to keep the external length L and the width J to a minimum for a specific heat duty/pressure drop. This allows the angle α to be designed to be sufficiently high, so fewer or no flow guiding vanes <NUM> are required to guide the first fluid flow through the heat exchanger <NUM>. Providing fewer flow guiding vanes <NUM> reduces the weight of the heat exchanger <NUM> and makes the design of the heat exchanger <NUM> easier.

Preferably, the angle α is between <NUM> to <NUM> degrees, more preferably between <NUM> degrees to <NUM> degrees, more preferably between <NUM> degrees to <NUM> degrees, more preferably between <NUM> degrees to <NUM> degrees. Providing the diverging angle α of between <NUM> to <NUM> degrees reduces the pressure drop of the first fluid within the heat exchanger <NUM> by providing a relatively larger cross-sectional area of the air side versus the flow length.

Further, the diverging heat exchanger cores <NUM> maximises the frontal area for the first fluid compared with other arrangements of heat exchangers cores. This leads to a lower pressure drop on the first fluid side and/or allows to use more heat transfer efficient geometries. This arrangement means that the heat exchanger <NUM> can employ more efficient (heat transfer wise) geometries for the first fluid exchanger side (e.g. the inlet <NUM> of the housing <NUM>).

This arrangement also provides a reduced weight of heat exchanger <NUM>. In one example, the heat exchanger <NUM> is approximately <NUM>-<NUM>% lower than "traditional" installations (e.g. the arrangement shown in <FIG>).

There are interesting counter/cross orientation of the first fluid flow and the second fluid flow in this diverging arrangement to bring thermal benefits too.

In one example, the geometry of the heat exchanger core <NUM> is as follows: <MAT> <MAT>.

Here x and y are the width and length of the housing <NUM>, respectively.

The sizes of other components (such as headers) within the heat exchanger <NUM> should be kept to a minimum to keep the weight in the heat exchanger <NUM> down.

The arrangement of the diverging heat exchanger cores <NUM> provides minimises the first fluid pressure drop through reducing the local Reynolds number inside the heat exchanger <NUM>.

<FIG> shows an alternative arrangement of the heat exchanger core <NUM> compared with the example shown in <FIG>. For clarity, the housing <NUM> is shown as transparent in <FIG> so the elements within the housing <NUM> are visible.

In this example, the heat exchanger cores <NUM> still meet at the junction <NUM>. However, the heat exchanger cores <NUM> then diverge towards the inlet <NUM> or the proximal end of the housing <NUM>. That is to say that the distance between the heat exchanger cores <NUM> increases from the junction <NUM> towards the inlet <NUM>.

In <FIG>, the wall <NUM> of the housing <NUM> comprises an aperture through which the second fluid can enter the core inlet <NUM>. In this arrangement, the second fluid would still be isolated from the first fluid as the second fluid would enter directly into a conduit or pipe of the heat exchanger core <NUM> that is isolated from the first fluid.

In the example shown in <FIG>, the core inlets <NUM> are arranged perpendicular to the longitudinal axis A-A of the housing <NUM> of the heat exchanger <NUM>, but other arrangements are possible. In this example, the core inlets <NUM> are arranged towards or adjacent to the inlet <NUM> of the housing <NUM>.

The core outlet <NUM> may be arranged at or adjacent to the junction <NUM>. The core outlet <NUM> may be arranged to be perpendicular to the longitudinal axis A-A of the housing <NUM>. In one example, the core outlet <NUM> is configured to be perpendicular to the core inlets <NUM>. In other examples, the core inlets <NUM> and core outlet <NUM> may be reversed from those shown in <FIG>. In other words, the second fluid may enter the heat exchanger core <NUM> at the core inlet <NUM>, which is located at or approximate to the junction <NUM> and the second fluid then travels through the heat exchanger core <NUM> towards the core outlet <NUM>, which may be located at or towards the inlet <NUM> or outlet <NUM> of the housing <NUM>.

As shown in <FIG>, the core inlets <NUM> of each of the heat exchanger cores <NUM> may be opposite to each other. That is to say that they are arranged on the opposite sides of the housing <NUM> relative to each other. The core outlets <NUM> of the heat exchanger cores <NUM> are arranged adjacent to each other.

In <FIG>, the first fluid flow enters the heat exchanger <NUM> via the inlet <NUM> in the direction represented by arrow F, i.e. substantially parallel to the longitudinal axis A-A of the housing <NUM>. The first fluid then passes through one or more first flow paths of the heat exchanger cores <NUM> before exiting the housing <NUM> at the outlet <NUM>. The first fluid flow exits the heat exchanger <NUM> in the direction indicated by arrow G in <FIG>. A second fluid enters the heat exchanger <NUM> via core inlets <NUM>. The second fluid may enter the heat exchange cores <NUM> in the direction indicated by arrows H in <FIG>.

The second fluid then travels within the heat exchanger core <NUM> and exits the heat exchanger core <NUM> at the core outlet <NUM>. In <FIG>, the second fluid exits the heat exchanger cores <NUM> in the direction indicated by arrow I.

In <FIG>, the core inlets <NUM> are shown substantially at or adjacent to the inlet <NUM> of the housing <NUM>. In other words, the core inlets <NUM> may be located at or adjacent to the proximal end of the housing <NUM>.

However, in other examples, there may be a gap between the core inlet <NUM> and the proximal end of the housing <NUM>. The angle between the heat exchanger cores <NUM> is the same as described above in relation to <FIG>.

The arrangement of the heat exchanger <NUM> of <FIG> provides the same advantages to the arrangement in <FIG>. That is to say that the pressure-drop of the first fluid entering the heat exchanger is significantly reduced.

In one example, the first fluid is air or another compressible fluid (gas). The second fluid may be an incompressible fluid, i.e. liquid such as water or oil.

The heat exchanger cores <NUM> may comprise a finned tube arrangement. <FIG> show an example of part of heat exchanger core <NUM> in the form of a finned tube. In this example, the first fluid travels in the direction indicated by arrow M through the heat exchanger core <NUM>. The first fluid travels through one or more first fluid paths through the heat exchanger core <NUM>. The first fluid path may be defined by a plurality of fins <NUM>.

The second fluid travels within the heat exchanger core <NUM> in conduits <NUM>. The fins <NUM> are thermally coupled to the conduits <NUM>.

<FIG> shows a cross section through the example shown in <FIG>, but with only a single tube <NUM>.

The heat exchanger cores <NUM> comprise a plate fin arrangement. Plate fin heat exchangers comprise a greater density than tube fin arrangements owing to their unique geometry which creates a greater surface area for heat transfer to take place. Therefore, plate fin heat exchangers can be made both smaller and more lightweight for a specified heat load or alternatively can dissipate a higher heat load without increasing in size and/or weight when compared to conventional tube fin heat exchangers. <FIG> show an example of part of a heat exchanger core <NUM> in the form of a plate fin arrangement. In this example, there are alternating layers of first fluid paths and second fluid paths. The first fluid may travel in a direction represented by arrow O and the second fluid may travel in a direction represented by arrow P. <FIG> shows an example of a cross-section through one of the fluid paths.

Plate fin heat exchangers may also be manufactured using additive manufacturing techniques, for example selective laser melting, selective laser sintering or directed energy deposition. Such manufacturing techniques allow complex plate fin heat exchanger geometries to be manufactured which are otherwise difficult or impossible with conventional manufacturing techniques. As such, plate fin heat exchangers may be manufactured with even greater surface areas than tube fin heat exchangers or conventionally manufactured plate fin heat exchangers thereby allowing the possibility of smaller, more lightweight heat exchangers for a specified heat load or alternatively the ability to dissipate a higher heat load without increasing in size and/or weight.

The heat exchanger <NUM> provides an increased frontal transfer area, which allows the reduction of the lower Reynolds number inside the heat exchanger <NUM> compared to traditional cuboid (<FIG>) or inclined installation. This in turn enables the use of more heat transfer efficient internal geometries which allow the reduction in the heat exchanger <NUM> installation volume and weight (up to <NUM>% when compared to traditional and <NUM>% when compared to the inclined). Additionally, the flow orientation of the first fluid and the second fluid is closer to the most efficient counter-flow in the heat exchangers <NUM> shown in <FIG> and <FIG>, compared to a standard cross-flow configuration found in the traditional cuboid or inclined heat exchanger designs, making the heat transfer more efficient and the heat exchanger <NUM> smaller for a given heat transfer requirement within a certain pressure drop restriction.

Where, in the foregoing description, integers or elements are mentioned that have known, obvious, or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the invention.

Claim 1:
A heat exchanger comprising:
a housing (<NUM>) comprising:
an inlet (<NUM>) at a proximal end for receiving a first fluid; and
an outlet (<NUM>), downstream of the inlet at the distal end of the housing, through which the fluid is configured to exit the housing (<NUM>); and a plurality of heat exchanger cores (<NUM>) within the housing (<NUM>);
wherein the plurality of heat exchanger cores (<NUM>) comprises a plate fin arrangement; and,
wherein the plurality of heat exchanger cores (<NUM>) comprise one or more first flow paths through which the first fluid can pass through the heat exchanger cores, in use, characterised in that the plurality of heat exchanger cores (<NUM>) meet at a junction and diverge from each other towards one of the inlet (<NUM>) or the outlet (<NUM>) of the housing (<NUM>).