Patent Description:
Today, a substantial number of heat exchangers are used in aircraft. Their size and weight is relatively small compared to the overall vehicle because the needed active heat transfer area is relatively small, driven by high temperatures differences or high accepted pressure losses. In classic turbine aircrafts, the system with the highest thermal energy are the fuel burn turbines. Such turbines are an open system, in which the hot exhaust gases do not need to be cooled. The turbines only need inner cooling, which is ensured by utilizing heat exchangers and/or film cooling in the high temperature / high pressure system, using compressed air.

In view of environmental protection efforts, alternative propulsion systems for aircraft applications are increasingly developed, and such systems may, for example, utilize hydrogen fuel cells as energy source for electric motors. The fuel cells provide electrical energy to the electrical motor that provides thrust via a propeller. The electrical energy is generated by an electrochemical process where hydrogen and oxygen react, thereby producing water, electricity, and heat. The maximum efficiency of this electrochemical process is currently limited to approximately <NUM>% (electricity), whereas approximately <NUM>% of the overall energy is dissipated in heat. Therefore, the fuel cells must be cooled down, to prevent overheating and efficiency reduction.

For primary propulsion purposes the necessary power is in the order of megawatts, which means that the heat rejected to the atmosphere will also be in the megawatt range. In case of low temperature fuel cells such as PEM's (proton exchange membrane), where the operation temperature is in the vicinity of <NUM>, due to the necessary high cooling power (MW range) and low differential temperature (down to some <NUM> - as minimum approach temperature), the cooling system therefore becomes massive, resulting in weight and drag issues.

<CIT> describes an aircraft that includes an aircraft heat source and a propulsion system including an electric propulsion engine. The electric propulsion engine includes an electric motor and a fan rotatable by the electric motor and the electric propulsion engine further defines a fan air flowpath. A thermal management system includes a heat source exchanger in thermal communication with the aircraft heat source, a heat sink exchanger in thermal communication with the fan air flowpath of the electric propulsion engine, and a thermal distribution bus extending from the heat source exchanger to the heat sink exchanger. A control system is operably connected to the thermal management system for selectively thermally coupling the heat sink exchanger with the heat source exchanger.

<CIT> describes systems and methods of heat management of turbine engines including turbofans, turboprops and turboshafts and fan driven propulsion systems. The propulsion system may comprise a fan, nacelle, an electrical or mechanical heat source and a cooling system consisting of heat exchangers in the fan duct and on the nacelle and coolant pumps. The heat source can be a motor or a generator or turbine machinery or accessories rotationally coupled to rotating shafts. The heat management system transfers heat to the air in the fan flow path to provide additional fan thrust. The heat management system also transfers heat to structural members in the gas flow path that require anti-icing.

<CIT> describes an integrated multimode thermal energy transfer system, method and apparatus for full-scale clean fuel electric-powered multirotor aircraft with automatic on-board-capability to provide sensor-based temperature awareness and adjustment to critical components and zones of the aircraft. Automatic computer monitoring, including by a programmed triple-redundant digital autopilot computer, controls each motor-controller and motor to produce pitch, bank, yaw and elevation, while simultaneously measuring, calculating, and adjusting temperature and heat transfer of aircraft components and zones, to protect critical components from exceeding operating parameters and to provide a safe, comfortable environment for occupants during flight. By using the results of the measurements to inform computer monitoring, the methods and systems can use byproducts including thermal energy disparities and differentials related to both fuel supply systems and power generating systems to both add and remove heat from different aircraft zones to improve aircraft function, comfort, and efficiency.

<CIT> describes a method of using a minimal surface or a minimal skeleton to make a heat exchanger component. The method comprises the steps of generating a stereolithography file from design data, slicing the stereolithography file into two-dimensional patterns, repeating the two-dimensional patterns sequentially to produce a three-dimensional minimal surface component or minimal skeleton component, and depositing at least one layer of a material having a high thermal conductivity onto a top surface of a base, wherein the deposited material forms either a three-dimensional minimal surface component or a three-dimensional minimal skeleton component. Also provided are the heat exchanger components made by the embodiments of the method using either minimal surfaces or minimal skeletons.

<CIT> describes a heat exchanger that includes a core comprising a single piece continuous boundary having a first surface defining a first labyrinth, and an opposing second surface defining a second labyrinth. A first inlet manifold is connected to the first labyrinth and configured to supply a first fluid to the first labyrinth, and a second inlet manifold is connected to the second labyrinth and configured to supply a second fluid to the second labyrinth. The core comprises a plurality of identical three dimensional unit cell structures replicated in three orthogonal spatial dimensions.

<CIT> describes mass transfer packing with a minimal surface or a triply periodic minimal surface which enables significantly improved performance for separation and mixing applications particularly with respect to distillation, liquid-liquid contacting, and heat exchange applications.

It is an objective to provide a cooling system for aircraft components having reduced weight.

This objective is solved by the subject matter of the independent claims. Further embodiments are described in the dependent claims as well as in the following description.

According to a first aspect, a component for an aircraft is provided. The component comprises at least one heat source, a housing enclosing the at least one heat source, at least one heat exchanger at least one heat sink, at least one structural suspension element, and an air duct. Each of the at least one structural suspension element is attached to an inner surface of the housing and supports one or more of the at least one heat source within the housing. Each of the at least one heat sink is an integrated part of an outer wall of the housing and is configured to guide air from an inside of the housing to an outside of the housing by allowing an air leakage through the outer wall of the housing to thereby convey thermal energy from the heat sink to the surroundings. Each of the at least one heat exchanger is thermally coupled to at least one of the at least one heat source (preferably, each heat exchanger is thermally coupled or assigned to a single heat source, which may include that multiple heat exchangers are thermally coupled to that single heat source; alternatively, a heat exchanger is thermally coupled to two or more adjacent heat sources, which may include that multiple heat exchangers are arranged so each heat exchanger is thermally coupled to two or more heat sources). Each of the at least one heat exchanger is fluidly connected to one of the at least one heat sink via an inlet line for a coolant (for example, a liquid coolant) flowing along one of the at least one structural suspension element. Each of the at least one heat sink is fluidly connected to at least one of the at least one heat exchanger via a return line for the coolant flowing along one of the at least one structural suspension element. The air duct is configured to guide ambient air from the outside of the housing through the housing, past each of the at least one structural suspension element, and through the at least one heat sink out of the housing, thereby enabling a cooling of the coolant flowing through each of the inlet paths and the return paths and through each of the at least one heat sink.

Modern aircrafts use a large number of devices that may need to be cooled in order not to be damaged or adversely affected. For example, an engine may employ certain components, such as electric motors or other components dissipating heat. However, other structures, such as, for example, a control surface, may also use certain actuators or other electrical devices generating heat, that may need to be cooled. The component described herein incorporates a cooling functionality for such components that adds less weight to the overall component, therefore facilitating compliance with weight requirements. In particular, this is achieved by merging several system functionalities of regular cooling systems, such as ducting, coolant piping, heat exchangers, and the housing of the component itself. In particular, part of the housing itself may act as a heat sink, as will be described below.

The heat sources may each be any device other structure that produces heat and that needs to be cooled. For example, the heat source may be an electric motor, a battery, a fuel cell or any other structure or device that produces heat. Such components may, for example, be used in a hydrogen powered aircraft engine. Further, if more than one heat source is present within the component, different heat sources may be of a different kind. So, for example, some of the heat sources may be electric motors, some of the heat sources may be fuel cell, some of the heat sources may be other electrical devices (such as actuators), as well as any possible combination of these variants. Fuel cells in particular produce a large amount of heat, apart from the needed electrical energy, that needs to be transported away in order for the fuel cell to work efficiently and not to overhead. It should be appreciated that the aforementioned heat sources are only exemplary in nature and the heat sources may also be any other heat source that needs to be cooled.

Each of the heat sources is placed within the housing. The housing may, for example, be the nacelle of an aircraft engine, in particular of a hydrogen or other electrically powered aircraft engine. However, the housing may in general be the housing of any component that includes a heat dissipating element, such as, for example, a wing or other control surface of an aircraft, that includes certain heat dissipating actuators or other devices. The housing encloses or surrounds the heat source, such that the heat source is arranged within the housing.

The structural suspension elements may, for example, be support struts which are projecting inward the housing and which are connected to an inner wall of the housing as well as to the heat source, such that the heat source is supported and held in place by the structural suspension elements. In other words, the structural suspension elements connect the heat source with an inner wall or other inner element of the housing and fixes (or at least participates in fixing) the heat source in place. For example, when the component is an aircraft engine, the structural suspension elements may be stiffening struts of other reinforcement elements which increase structural integrity of the housing itself and which hold the heat source within the housing.

Each of the at least one heat exchanger is thermally coupled to at least one of the heat sources. This means, the corresponding heat exchanger is arranged to convey thermal energy away from the at least one heat source. Each heat source may have a dedicated heat exchanger of some heat sources may share a common heat exchanger. The respective heat exchanger may be in direct contact with the respective heat sources. However, it is also conceivable that the heat exchanger is not in direct contact, i.e., does not directly abut the heat sources, but is arranged in the vicinity of the corresponding heat sources, such that the thermal energy from the heat sources may be coupled into the heat exchanger by way of the thermal radiation. However, any thermal coupling is conceivable. The heat exchangers itself may be any regular heat exchangers, which are known in the art.

The heat sink or heat sinks is/are part of the housing itself. For example, the housing may in general have a surrounding wall, parts of which are replaced by corresponding heat sink structures, so that the corresponding part of the wall is configured to receive and conduct a coolant, like a liquid coolant. When the coolant passes the corresponding structure, it may be cooled by air passing by or through the heat sink from the inside of the housing to the surrounding. During this process, the passing air conveys the thermal energy from the heat sink to the surroundings of the housing and therefore of the component. For this, the heat sink may have a geometrical structure having a large overall surface. Further, the intended air leakage through the heat exchangers slows down the air speed within the air duct to a required level for a final heat exchanger state (described further below), thereby leading to less geometrical restrictions and size. This in particular enables to build a shorter housing.

Each of the heat exchangers is connected to at least one of the heat sinks by an inlet line. This inlet line fluidly connects the respective heat exchanger with the respective heat sink, so that the coolant can be transported from the heat exchanger to the heat sink. The corresponding inlet line runs along one of the at least one structural suspension element. The inlet line may, for example, be a regular tube or pipe running along the outside of the structural suspension element. However, the inlet line may also be integrated in the corresponding structural suspension element. For example, the structural suspension element may also be hollow and directly merge into the heat sink, such that the coolant may flow directly within the structural suspension element into the heat sink. Further, instead of the coolant flowing directly within such a cavity of the structural suspension element, a regular tube or pipe may be running along the structural suspension element within the inner cavity.

Analogously to the inlet lines, each of the return lines connects a respective heat sink with at least one heat exchanger via one of the structural suspension elements. Preferably, a return line for one of the heat exchangers runs along a structural suspension element which is different from the structural suspension element along which the inlet line for this particular heat exchanger runs. The coolant runs from the heat sink through the return line back into the heat exchanger.

The air duct is built by the space between the inner wall of the housing and the heat source(s), so that the structural suspension elements together with the inlet and return lines pass through the air duct. Air can pass into the housing through an opening of the housing, which may, for example, as described further below, include a fan for controlling the flow of air into the air duct and therefore the pressure within the air duct. Additionally, flaps or other mechanically adjustable structures may be placed within the opening in order to control the flow of air into the air duct. Since the structural suspension elements together with the inlet and return lines for the coolant pass through the air duct, the air duct itself acts as a heat exchanger. In particular, air flowing through the air duct gets heated by the coolant flowing through the inlet and return lines, thereby conveying the thermal energy dissipated from the inlet and return lines. Further, air flowing out of the housing through the heat sink absorbs heat from the heat sink, thereby further cooling the coolant, which in turn cools the heat sources.

By combining the housing with the heat sink and combining the structural suspension elements with inlet lines and return lines for the heat exchangers arranged at the heat sources, the air duct itself together with these components builds a heat exchanger with a large heat dissipation surface, thereby facilitating enough cooling power while reducing weight compared to regular cooling system.

According to an embodiment, the at least one heat source is a fuel cell or an electric motor or an arrangement of one or more electric motors and one or more fuel cells.

In particular, for example, when the component is an aircraft engine, one or more electric motors may be placed together with one or more fuel cells along a common longitudinal axis and each of the electric motors / fuel cells may have a heat exchanger that is connected to one or more heat sinks within the housing (as described above) by a corresponding inlet line and return line within or along corresponding structural suspension elements, such as reinforcement struts. However, the electric motors and the fuels cells (if more than one such device is present) do not need to be placed in line, but rather may be arranged in any suitable position.

According to another embodiment, the component further comprises a fan. The fan is arranged in an opening of the housing. The fan is configured to control air flow from the outside of the housing into the air duct.

For example, if the component is a propeller aircraft engine, the fan may be arranged coaxially with the propeller on the driveshaft of the propeller at a front end of the engine. A gear set may further be arranged between the fan and the drive shaft, such that the rotational speed and the direction of rotation of the fan may be adjusted independently of the rotational speed and direction of the propeller. This allows to control the air intake into the air duct (and therefore the pressure inside the air duct). On the one hand, during a takeoff procedure on the runway, for example, the speed of the aircraft and therefore the relative air speed with regard to the aircraft is low. Further, in this situation, the engine runs under high load, producing an increased amount of heat. In order to account for this, the fan may be controlled to blow additional air into the air duct, to provide enough cooling power. On the other hand, when the aircraft is travelling at high altitude at cruise speed, the engine may run at a lower, constant output. Also, because of the higher speed, the relative air speed is higher. In this situation, the fan may be used to decelerate the intake air speed (e.g., to approximately <NUM> Mach).

If the component is not an engine, a similar fan setup may be utilized to control air flow into the air duct accordingly.

According to another embodiment, the fan is configured to be controlled to control an air flow into the housing such that a pressure difference between the inside of the housing and the outside of the housing is established that supports removal of the air from the inside of the housing through the heat sink utilizing the venturi effect.

By adjusting the air intake utilizing the fan, the internal pressure inside the air duct can be adjusted. Therefore, the pressure difference between the air duct and the surroundings of the component, e.g., an aircraft engine, can be adjusted. Since the heat sink is part of the housing and has a structure that allow for air to pass through the heat sink, by appropriately adjusting the pressure within the air duct, the venturi effect may be utilized to control the air flow through the heat sink, as will be readily apparent.

According to another embodiment, the heat sink comprises a functional cellular geometry.

Such a function cellular geometry in general comprises a cell geometry that is configured to balance the desired mechanical properties, such as mechanical strength with the desired thermal heat transfer properties. The functional cellular geometry in general is at least partially permeably for air and provides enough contact surface for the air passing through the heat exchanger.

According to another embodiment, the functional cellular geometry comprises a gyroid structure.

Such gyroid structures are advantageous with regard to both mechanical stability as well as heat transfer properties. However, other bionic structures are conceivable, too.

According to another embodiment, the housing further comprises at least one suction area and/or at least one blowing area for laminar flow control to avoid flow separation from the outside of the housing.

The air flow from the air duct through the heat sink exits the housing at an outer surface of the component (for example a control surface or an engine). Hence, the exiting air flow through the heat sink at the outer boundary layer of the housing influences the flow of the ambient air. In order to avoid in-flight flow separation and to ensure laminar flow at the boundary layer, suction and blowing areas may be employed, to blow air into or suck air out of the boundary layer at appropriate locations of the housing. This principle is in general known, e.g., for aircraft wings.

According to another embodiment, the component is a control surface of an aircraft.

Such a control surface may be any surface which is configured to control the spatial orientation of the aircraft, e.g., to control the pitch, roll, and yaw angles. Usually, control surfaces employ actuators or other mechanical displacement devices, in order to move parts of the corresponding surface. These actuator devices produce heat and may need to be cooled.

Appropriate cooling may be achieved by the principles described above.

According to another embodiment, the control surface of the aircraft is one of an elevator, a rudder and a wing.

According to another embodiment, the component is an aircraft engine and the housing is a nacelle of the aircraft engine.

According to another embodiment, the aircraft engine is an electric propeller engine comprising an electric motor, at least one hydrogen fuel cell, and at least one hydrogen tank. The electric motor is powered by the at least one fuel cell. The electric motor and/or the at least one fuel cell each are one of the at least one heat source.

The electric motor and the fuel cells may be arranged in line along the longitudinal axis of the engine and may each be supported by corresponding structural suspension elements, as described above.

According to another embodiment, the air duct runs from a front end of the nacelle to a rear end of the nacelle.

Aircraft engines are mounted along a longitudinal direction of the aircraft. The front end of the nacelle corresponds to the front of the engine in the flight direction. The rear end is opposite the front end in the longitudinal direction and is directed towards the aft of the aircraft. In the center of the nacelle, around the longitudinal axis, multiple heat sources such as fuel cells or electric motors may be arranged. The heat sources may be supported within the center of the nacelle by the structural suspension elements, as described above. The air duct therefore circularly surrounds the heat sources and runs along the longitudinal direction of the engine, thereby building a shell-shaped duct.

Optionally, at the front end of the nacelle, a fan, such as described above, may be arranged coaxially around the longitudinal center axis and may be placed within an opening of the nacelle. This allow for the fan to be used to control the air flow from the front end of the engine into the air duct. At the rear end, the nacelle may be closed by a final heat exchanger stage.

According to another embodiment, the housing further includes a final heat exchanger stage at the rear end.

Such a final heat exchanger stage may be a regular heat exchanger that is partially permeable for air. Such a heat exchanger may, for example, be circularly shaped to close the shell-shaped air duct at the rear end of the nacelle. Air that has not already exited the air duct through the heat sink can exit the air duct through the final heat exchanger stage. The coolant from the heat sink may be directed through the final heat exchanger stage, in order to further extract heat from the coolant before the coolant is routed back to the heat exchangers that are thermally coupled to the heat sources, as described above.

According to another embodiment, the heat sink further is configured for de-icing of the housing.

When the air from the air duct (or at least part of the air, if a final heat exchanger stage is used) is routed past the inlet and return lines and exits the housing through the heat sink, the air is heated. Therefore, on the one hand, the heat sink itself, and on the other hand, the heated air exiting the component, may be utilize for de-icing of the surface of the component. When the component is an aircraft engine that is mounted below a wing of an aircraft, the hot air may further be utilized for de-icing of the wing, as will be readily apparent.

According to a second aspect, an aircraft is provided. The aircraft comprises a fuselage and at least one component according to any one of the preceding claims.

The component may be designed according to any one of the embodiments described above.

In particular, the component may be an engine or any control surface of the aircraft, as described above.

In summary, the present disclosure provides an aircraft component with integrated cooling capabilities for thermal loads such as fuel cells or electric motors, while simultaneously complying with weight requirements. In particular, by integrating one or more heat sinks into the housing of the component utilizing functional cellular geometries, such as gyroid geometries, and by integrating the inlet and return lines into already present structural suspension elements for the heat sources, a large cooling area can be provided without overly increasing the weight of the component.

Although the present disclosure is described with regard to aircraft applications, it should be noted, that the disclosure may be used for any other suitable application, such as for automotive applications, train application, and similar applications where a lightweight cooling system for high thermal loads is desired.

Further, although mainly described with regard to aircraft engines or aircraft control surfaces, it should be appreciated that the described cooling system may be employed with any component of an aircraft where integrated cooling functionality is desirable. For example, the cooling system may also be used in aircraft wings, such that the cooling system is part of a wing airframe or of a front fuselage airframe where components need to be cooled. For that, for example, integrated ducts may be included within the corresponding components (such as running through a wing of the aircraft) according to the principles described herein.

In the following, exemplary embodiments are described in more detail having regard to the attached figures. The illustrations are schematic and not to scale. Identical reference signs refer to identical or similar elements. The figures show:.

<FIG> schematically show cut views of a component <NUM>, which is an aircraft engine <NUM>. <FIG> shows a schematic cut view of the aircraft engine <NUM>, including the respective flows of air and cooling, which preferably is liquid cooling. However, although liquid cooling is provided herein as an example, it should be understood that the description is not limited to using a liquid coolant. <FIG> is a simplified illustration of the aircraft engine <NUM> of <FIG>, showing only the structural components of the aircraft engine <NUM> without any flow paths for air and liquid coolant, but illustrating the three-dimensional structure of the aircraft engine <NUM>. In the following, <FIG> will be described together.

The illustrated aircraft engine <NUM> comprises a housing <NUM> (the nacelle <NUM>) enclosing the inner parts of the engine. The nacelle <NUM> includes four integrated heat sinks <NUM>. It should be noted that the four heat sinks <NUM> run around the nacelle <NUM> in a circumferential direction of the nacelle <NUM>. Each of the heat sinks <NUM> thereby may be running continuously around the full circumference or may be interrupted by regions without heat sink properties. The aircraft engine <NUM> further includes a fan <NUM> at an intake opening at a front end <NUM>. With regard to a longitudinal direction <NUM> of the aircraft engine <NUM>, the fan <NUM> is arranged in the intake opening of the nacelle <NUM> between a propeller <NUM> and the front end <NUM> of the nacelle <NUM>.

In the center of the nacelle <NUM> behind the fan <NUM>, along a common longitudinal axis, are arranged an electric motor <NUM> as well as three arrangements of fuel cells <NUM> (which may for example be proton exchange membrane fuel cells (PEM fuel cells)). Each of the three arrangements of fuel cells <NUM> includes six fuel cells <NUM>, which can best be seen in <FIG> (two fuel cells <NUM> at the opposite side of the drawing plane are not visible). The illustrated aircraft engine <NUM> further includes two hydrogen tanks <NUM> for providing the fuel cells <NUM> with hydrogen. Each of the fuel cells <NUM> and the electric motor <NUM> are mounted on a central longitudinal axis of the nacelle <NUM>, which corresponds to the axis of rotation of the propeller <NUM>. Further, each of the fuel cells <NUM> and the electric motor <NUM> are connected to the nacelle <NUM> by structural suspension elements <NUM>.

When in operation, the fuel cells <NUM> and the electric motor <NUM> produce heat. Therefore, the fuel cells <NUM> and the electric motor <NUM> may be commonly referred to herein as heat sources <NUM>.

A typical heat exchanger <NUM> is arranged in the center of each of the arrangements of fuel cells <NUM> and of the electric motor <NUM>. However, these heat exchangers <NUM> may be arranged at any possible location that allow for a thermal coupling to the corresponding heat sources <NUM>. Further, each of the fuel cell may include a separate heat exchangers <NUM>. Inlet lines <NUM> and return lines <NUM> fluidly connect each of the heat exchangers <NUM> with a corresponding heat sink <NUM>. The inlet lines <NUM> allow hot liquid coolant from the heat exchangers <NUM> to flow into the heat sinks <NUM>. The return lines lead back the cooled liquid coolant from the heat sinks <NUM> into the heat exchangers <NUM>. In the illustrated configuration, the inlet lines <NUM> and the return lines <NUM> each run inside a structural suspension element <NUM>. Thereby, in the illustrated configuration, the return lines <NUM> run through different structural suspension elements <NUM> than the inlet lines <NUM>, in order to avoid for the cooled liquid coolant in the return lines <NUM> from being heated by the hot liquid coolant in the inlet lines <NUM> before returning into the heat exchangers <NUM>. In <FIG>, only one plane of structural suspension elements <NUM> is shown. However, it should be appreciated that in general, each of the fuel cells <NUM> may be connected to corresponding heat exchangers <NUM> by a structural suspension element <NUM>.

Further, the liquid coolant may be directed through only some of the heat sinks <NUM> or through all of the heat sinks <NUM> in line before returning to the heat exchangers <NUM> via the return lines <NUM>.

The space between the inner wall of the nacelle <NUM> and the heat sources <NUM> and the hydrogen tanks <NUM> acts as an air duct <NUM> that circumferentially encloses the heat sources <NUM>. Further, in <FIG>, the aircraft engine <NUM> includes a final heat exchanger stage <NUM> at the rear end <NUM> of the nacelle <NUM>, which closes the back of the nacelle <NUM> (or rather of the air duct <NUM>) and which is at least partially permeable for air. This final heat exchanger stage may be any regular heat exchanger.

The structural suspension elements <NUM> may, for example, be stiffening struts, which structurally reinforce the nacelle <NUM> while simultaneously providing support for the fuel cells <NUM> and the electric motor <NUM>. Since the air duct <NUM> encloses the heat sources <NUM> and runs form the front end <NUM> to the rear end <NUM>, and since the structural suspension elements <NUM> (including the inlet lines <NUM> and return lines <NUM>) run in a substantially radial direction between the heat exchangers <NUM> and the heat sinks <NUM> (integrated into the wall of the nacelle <NUM>), air passing through the air duct <NUM> from the front end <NUM> to the rear end <NUM> flows around the structural suspension elements <NUM>. Thereby, heat from the inlet lines <NUM> and return lines <NUM> (running through the structural suspension elements <NUM>) is transferred to the air. The air afterward passes through the heat sinks <NUM> integrated into the housing <NUM> (nacelle <NUM>), thereby further absorbing heat from the heat sinks <NUM>. The remaining air may pass through the final heat exchanger stage <NUM>. The flow of air is illustrated in <FIG> by arrows.

The flow of air through the air duct <NUM> may be controlled by the fan <NUM>. The fan <NUM> may also be driven by the electric motor <NUM>. Further, an adjustable gear set (not shown) may be arranged between the fan <NUM> and the drive shaft of the electric motor <NUM>, such that the rotational direction and speed of the fan <NUM> is adjustable independently of the rotational speed and direction of the propeller <NUM>. This allows to control the air intake into the air duct (and therefore the pressure inside the air duct). For example, during a takeoff procedure on the runway, the speed of the aircraft and therefore the relative air speed with regard to the aircraft is low. Further, in this situation, the aircraft engine <NUM> runs under high load, producing an increased amount of heat. In order to account for this, the fan <NUM> may be controlled to blow additional air into the air duct, to provide enough cooling power. When the aircraft is travelling at high altitude at cruise speed, the engine may run at a lower, constant output. Also, because of the higher speed, the relative air speed is higher. In this situation, the fan <NUM> may be used to decelerate the intake air speed to the required level (e.g., to approximately <NUM> Mach). Also, the fan <NUM> may be used to adjust the internal pressure and air speed in the air duct <NUM> with regard to the surrounding of the aircraft engine <NUM> such that the venturi effect may be utilized to draw the air through the heat sinks <NUM>.

The heat sinks <NUM> are built using a functional structural geometry, such as a gyroid structure, as described above. This allows for high mechanical strength while simultaneously providing a large contact area for the air passing through the structure, thereby enabling good heat transfer properties.

By merging the inlet lines <NUM> and return lines <NUM> in the described way, and by merging the heat sinks <NUM> into the wall of the nacelle <NUM>, the weight of the aircraft engine <NUM> may be greatly reduced while still providing the necessary cooling power for the heat sources <NUM>. Further, utilizing the above-described intended air leakage through the outer wall of the nacelle <NUM> slows down the air passing through the air duct <NUM> from the front end <NUM> to the rear end <NUM> to a required level for the final heat exchanger stage <NUM>. This allows for a shorter nacelle <NUM>, further contributing to the minimization of weight.

The nacelle <NUM> may further be built for increased mechanical strength at region where high mechanical loads occur, such as at attachment points. Further, an outer shell <NUM> (<FIG>) may allow for structural reinforcement at such regions.

<FIG> further indicates a suction area <NUM> and/or a blowing area <NUM> at a front end of the nacelle. Such suction and/or blowing areas may be employed for laminar flow control to avoid flow separation from the housing. Such suction/blowing areas <NUM>, <NUM> may be employed to ensure laminar flow around the housing, as described further above. It should be appreciated that the location of the suction/blowing area <NUM>, <NUM> as shown in <FIG> is only exemplary in nature. Suction areas <NUM> and/or blowing areas <NUM> may present at any desired location in order to ensure laminar flow.

<FIG> shows a schematic outer view of the aircraft engine <NUM> of <FIG>. In <FIG>, the outer shell <NUM> is visible. The outer shell is a discontinuous sheet structure that encloses the outer surface of the nacelle <NUM>, having cutouts at the regions where the heat sinks <NUM> are arranged. This allows for structural reinforcement, similarly to a honeycomb structure, in order to achieve the required mechanical strength.

<FIG> shows an aircraft <NUM> having a fuselage <NUM>. The aircraft includes two of the electric propeller aircraft engines <NUM> described with regard to <FIG>. By utilizing the integrated cooling concept of the aircraft engine <NUM>, the overall weight of the aircraft <NUM> may be reduced. Further, the air flow passing through the wall of the nacelle <NUM> may be used for de-icing of the surfaces of the nacelle <NUM> as well as for de-icing of the wings of the aircraft.

Claim 1:
Component (<NUM>) for an aircraft (<NUM>), the component (<NUM>) comprising:
at least one heat source (<NUM>);
a housing (<NUM>) enclosing the at least one heat source (<NUM>);
at least one heat exchanger (<NUM>);
at least one heat sink (<NUM>);
at least one structural suspension element (<NUM>); and
an air duct (<NUM>);
wherein each of the at least one structural suspension element (<NUM>) is attached to an inner surface of the housing (<NUM>) and supports one or more of the at least one heat source (<NUM>) within the housing (<NUM>);
wherein each of the at least one heat sink (<NUM>) is an integrated part of an outer wall of the housing (<NUM>) and is configured to guide air from an inside of the housing (<NUM>) to an outside of the housing (<NUM>) by allowing an air leakage through the outer wall of the housing (<NUM>) to thereby convey thermal energy from the heat sink to the surroundings;
wherein each of the at least one heat exchanger (<NUM>) is thermally coupled to at least one of the at least one heat source (<NUM>);
wherein each of the at least one heat exchanger (<NUM>) is fluidly connected to one of the at least one heat sink (<NUM>) via an inlet line (<NUM>) for a coolant flowing along one of the at least one structural suspension element (<NUM>);
wherein each of the at least one heat sink (<NUM>) is fluidly connected to at least one of the at least one heat exchanger (<NUM>) via a return line (<NUM>) for the coolant flowing along one of the at least one structural suspension element (<NUM>); and
wherein the air duct (<NUM>) is configured to guide ambient air from the outside of the housing (<NUM>) through the housing (<NUM>), past each of the at least one structural suspension element (<NUM>), and through the at least one heat sink (<NUM>) out of the housing, thereby enabling a cooling of the coolant flowing through each of the inlet line (<NUM>) and the return line (<NUM>) and through each of the at least one heat sink (<NUM>).