Infrared camera fuel cell system for unmanned aerial vehicles

Abstract

System comprising a fuel cell operated with an anode gas, an infrared camera, a tank filled with liquid anode gas, evaporation means for evaporating the anode gas, and heat transfer means, wherein the heat transfer means, in the operating state, transfer heat from the infrared camera to the evaporated anode gas.

Description

[0001] The present invention relates to a system comprising a fuel cell and a cooled infrared camera, as well as to an unmanned aerial vehicle and a method for operating an unmanned aerial vehicle.

[0002] An infrared camera, or thermal imaging camera, can be used to capture the thermal radiation of an animate or inanimate body. The recording is done either passively, based solely on the object's thermal radiation, or actively, by simultaneously irradiating the object under investigation with infrared light.

[0003] Infrared cameras are used for monitoring and detection, among other things. They are also used in materials testing, for example, in the inspection of aircraft structural components such as a rudder. They can be used to detect cracks or other material discontinuities. Particularly sensitive infrared cameras are required for this task. These cameras feature photodetectors whose function is based on the photoelectric effect.

[0004] In order to reduce their own thermal radiation output, to avoid self-induced detection and thus to suppress their own temperature-induced noise overall, these detectors have a cooling system: In principle, both active and passive cooling are possible.

[0005] Passive cryogenic cooling is structurally simple and relies on a cold reservoir provided by a suitable cryogenic fluid, often liquid nitrogen, which can cool the infrared camera to 77 K. The corresponding cryogenic cooling system has a significant additional weight due to, among other things, the quality requirements and the required quantity of coolant. Furthermore, regular refilling of the cryogenic fluid is required, and energy is required to cool the evaporated cryogenic fluid.

[0006] Active cooling, on the other hand, is usually achieved using a cryocooler. This requires electrical power to operate the cooler. Furthermore, the design is significantly more complex, as cryocoolers require moving parts with extremely tight tolerances. Furthermore, cryocoolers require regular maintenance to maintain their functionality.

[0007] US Patent No. 4,920,412 A relates to an optical system for imaging the environment behind obstacles using an infrared camera in aircraft. The need for cooling is mentioned, but no cooling principle is described.

[0008] US 2013 / 0 076 900 A1 discloses a lens system for an infrared camera for use in a lens system for aerial reconnaissance, particularly for unmanned aerial vehicles. While the document discloses the need to cool the lens and detector system, it only discloses the use of known and therefore heavy cooling systems.

[0009] Furthermore, US 2022 / 0 311 955 A1 discloses a recording device for capturing images in the infrared range for use in unmanned aerial vehicles. This device is composed of a series of thin-layer spatial filters and, due to a detection technology that deviates from the standard, requires no cooling. Therefore, it is not an infrared camera in the conventional sense. The quality of the images, the precise range of application, and the reliability of the technology are therefore still questionable. Thus, the weight problem of cooling remains when using common and proven infrared camera technologies in unmanned aerial vehicles.

[0010] US Pat. No. 5,166,789 A discloses a combination of IR cameras and video cameras on manned aircraft for identifying geographically relevant points. Although it is described that the IR camera must have a cooling system, there is no problem with the weight of the cooling system in manned aircraft.

[0011] Therefore, an object of the invention is to propose a system that ensures the reliable operation of a cooled infrared camera while reducing the required resources.

[0012] Furthermore, the invention relates to a fuel cell-powered unmanned aerial vehicle having a cooled infrared camera.

[0013] In order to inspect aircraft structural components using a redesignated aircraft, the aircraft's power supply must be capable of supporting the weight of the infrared camera and its cooling system, or of powering their cooling system. In particular, the power supply must be capable of providing this power for a sufficient period of time, with the potential flight duration decreasing with increasing power load.

[0014] When using fuel cells to power the aircraft, only a comparatively low power output can be provided, which is why the weight of the aircraft must be minimized. The transport and operation of a conventional infrared camera system with active or passive cooling is therefore only possible for a significantly reduced time and with increased energy consumption.

[0015] DE 10 2011 014 565 A1 discloses a method for improved operation of a fuel cell system in an aircraft. This method involves using heat extracted from cabin air to be cooled to heat cryogenic hydrogen for fuel cell operation. The use of an IR camera is not provided.

[0016] It is therefore a further object of the invention to propose a fuel cell-powered aircraft with a cooled infrared camera, the energy consumption of which is minimized and the possible flight time of which is maximized.

[0017] Furthermore, it is an object of the invention to propose a method for the fuel-reduced operation of a fuel cell-powered, unmanned aerial vehicle which is capable of taking thermal images.

[0018] The first object is achieved by a system according to claim 1.

[0019] A system according to the invention thus comprises a fuel cell operated with an anode gas, whereby the fuel cells that can generally be used in the system are not limited to hydrogen-powered fuel cells. The system also comprises a tank filled with liquid anode gas. Corresponding storage containers for storing, in particular, liquid hydrogen or other known liquid anode gases are widely known from the prior art. A tank with a comparatively low weight is advantageously used. Gaseous anode gas is required for the operation of the fuel cell, whereby its required inlet temperature at the anode depends on the type of fuel cell and is typically in the range between 20°C and 150°C. Therefore, the system according to the invention comprises evaporation means for evaporating the anode gas.Furthermore, it comprises heat transfer means, which, in the operating state, transfer heat from the infrared camera to the vaporized anode gas. The person skilled in the art will also select suitable transport means and materials to ensure safe transport of the liquid or gaseous anode gas to the respective components, or appropriate means to ensure a suitable flow.

[0020] This allows for structurally simple, passive cooling of the infrared camera, eliminating the need for additional cooling fluid or the need to provide additional energy for cooling, as is required in conventional cooling systems. Furthermore, the heat dissipated by the infrared camera during cooling is used to heat the vaporized anode gas. This reduces the energy required to bring the anode gas to the fuel cell's operating temperature.

[0021] In an embodiment of the system according to the invention, the anode gas is hydrogen. This allows the use of a known and readily available fuel that can be combined with various fuel cell types.

[0022] In a further development of the invention, it is provided that the heat transfer means are designed as heat exchangers and / or the evaporation means are designed as evaporators.

[0023] This enables easy implementation of the corresponding components.

[0024] In an embodiment of the invention, it is also provided that the fuel cell is designed as a low-temperature fuel cell.

[0025] This enables comparatively simple operation of the fuel cell, which can be advantageously combined with mobile applications in particular.

[0026] It is also intended that the evaporation agents utilize ambient heat.

[0027] In this way, no separate energy supply is necessary to provide the evaporation energy, which advantageously reduces the system components and its energy requirements.

[0028] In a further development of the system according to the invention, it is provided that it has a further heat exchanger which is arranged downstream of the heat transfer means and upstream of the fuel cell.

[0029] This allows for further heating of the anode gas. Since the efficiency of fuel cells is temperature-dependent, effective use is only possible at a sufficiently high temperature. This system thus enables improved fuel cell usability.

[0030] It is also provided that the system according to the invention comprises a motor in its design, wherein the motor is driven by the fuel cell.

[0031] This means that the system according to the invention can be combined with various mobile applications.

[0032] The further object of the invention is achieved by an aircraft according to claim 8.

[0033] This advantageously utilizes the previously described system of a cooled infrared camera combined with a fuel cell. This significantly reduces the weight of the infrared camera. Additional energy is not required to cool the infrared camera, as the hydrogen must be fed to the fuel cell for operation anyway, and it must first be supplied with evaporation heat and additional heat to achieve a sufficient temperature increase. This makes it possible to carry such a cooled infrared camera on an unmanned aircraft even with a comparatively low energy supply, and it can be combined with a fuel cell drive. This enables the inspection of aircraft structural components and other surveillance and detection tasks that require corresponding energy resolution using unmanned, fuel cell-powered aircraft.

[0034] The method task for the operation of an unmanned aircraft, wherein the aircraft has an infrared camera and is operated via a fuel cell, is solved according to the invention by a method comprising the following steps: - Evaporation of liquid anode gas - Operating an infrared camera - Transfer of heat, especially radiant heat, from the operation of the infrared camera to the vaporized anode gas - Feeding the heated anode gas into a fuel cell

[0035] The evaporation of the liquid anode gas, preferably hydrogen, is essential for the operation of the fuel cell, as it requires the anode gas in a gaseous state. Further heating of the anode gas after evaporation is also necessary to bring the anode gas to the fuel cell's operating temperature, which, depending on the fuel cell type, is at least well above 20°C. However, heat must be removed from a cooled infrared camera to operate. Supplying the fuel cell with anode gas thus forms a heat sink, while operating an infrared camera to be cooled forms a heat source. The invention advantageously proposes a combination of heat source and heat sink, thereby minimizing the external energy and resource requirements for cooling the infrared camera and thus for its operation.Therefore, the fuel cell-powered aircraft provides sufficient energy for the continuous operation and transport of a cooled infrared camera, which can be used for inspection and surveillance tasks. The heat from the infrared camera is dissipated primarily via convection and dissipated via a metallic heat exchanger.

[0036] In a further development of the method according to the invention, ambient heat is used to evaporate the liquid anode gas. Since the ambient air is already present and has a significantly higher temperature than the liquid anode gas, the heat from the ambient air is sufficient to evaporate the anode gas, and no additional energy is required.

[0037] It is also planned that the heated anode gas will be further heated before being fed into the fuel cell.

[0038] This allows the fuel cell to operate in a higher temperature range and has improved efficiency.

[0039] The invention is described by way of example in a preferred embodiment with reference to a drawing, wherein further advantageous details can be taken from the figures of the drawing.

[0040] Functionally identical parts are provided with the same reference symbols.

[0041] The figure in the drawing shows in detail: Fig. 1: An embodiment of the system according to the invention.

[0042] In the Fig.Figure 1 shows an embodiment of the system according to the invention comprising a fuel cell 1 and an infrared camera 2 to be cooled. The fuel cell 1 is divided into various types depending on the electrolyte used, the fuel supplied to an anode 10, and the oxidant used at a cathode 11. In the system according to the invention, hydrogen is preferably used as the anode gas and oxygen as the oxidant. Due to the simpler structure and the lower heat required, a low-temperature fuel cell is also preferred by the invention. Liquid anode gas 5 is stored in a tank 3. However, comparatively warmer anode gas is required in the fuel cell 1; therefore, the liquid anode gas 5 is first fed via a pump 9 to evaporation means 6 designed as an evaporator 8. There, the liquid anode gas 5 enters the gaseous phase.The necessary heat of vaporization is supplied to the evaporator 8 in the embodiment shown via ambient heat Qu, meaning that no separate energy supply needs to be provided to the system at this point. The now vaporized anode gas 5' is passed on from the evaporator 8. The vaporized anode gas 5' still has a temperature that is below the operating temperature of the fuel cell 1, meaning that heat still needs to be supplied to the anode gas at this point. The infrared camera 2, on the other hand, requires cooling in order to reduce its thermal radiation and achieve the necessary resolution during operation. Heat Qs must therefore be dissipated from the infrared camera. According to the invention, the "cold" vaporized anode gas 5' serves as the cooling means. Therefore, according to the invention, heat transfer takes place in a heat transfer medium 7 designed as a heat exchanger 4. As a result, heat Qs emitted by the infrared camera 2, among other things,Radiant heat is transferred to the vaporized anode gas 5'. In the illustrated embodiment, the temperature of the anode gas 5" heated in this way is still below the operating temperature of the fuel cell 1, which is why additional heat Q+ is introduced into the system from the outside in a further heat exchanger 4', or rather, is transferred to the heated anode gas 5". This is then fed to the anode 10 of the fuel cell 1. In particular, this is not a single fuel cell 1, but rather an array of similar fuel cells 1. LIST OF REFERENCE SYMBOLS 1 fuel cell 2 infrared cameras 3 tanks 4 heat exchangers 4' additional heat exchanger 5 liquid anode gas 5' vaporized anode gas 5" heated anode gas 6 evaporation agents 7 Heat transfer media 8 evaporators 9 Pump 10 Anode 11 Cathode Qu ambient heat Qs heat Q+ additional heat

Claims

[1] System comprising a fuel cell (1) operated with an anode gas, an infrared camera (2), a tank (3) filled with liquid anode gas (5), evaporation means (6) for evaporating the anode gas, and heat transfer means (7), wherein the heat transfer means (7) in the operating state transfer heat (Qs) of the infrared camera (2) to the evaporated anode gas (5'). [2] The system of claim 1, wherein the anode gas is hydrogen. [3] System according to claim 1 or 2, wherein the heat transfer means (7) are designed as heat exchangers (4) and / or the evaporation means (6) are designed as evaporators (8). [4] System according to claim 1, 2 or 3, wherein the fuel cell (1) is designed as a low-temperature fuel cell. [5] System according to one of the preceding claims, wherein the evaporation means (6) utilize ambient heat (Qu). [6] System according to one of the preceding claims, wherein the system comprises further heat transfer means (7'), in particular a further heat exchanger (4'), which are arranged downstream of the heat transfer means (7) and upstream of the fuel cell (1). [7] System according to one of the preceding claims, further comprising a motor, wherein the motor is driven via the fuel cell (1). [8] An unmanned aerial vehicle comprising a system according to any one of claims 1 to 7. [9] Method for operating an unmanned aircraft, wherein the aircraft has an infrared camera (2) and is operated via a fuel cell (1), comprising the following steps: - Evaporation of liquid anode gas (5) - Operating an infrared camera (2) - Transferring heat (Qs), in particular radiant heat, from the operation of the infrared camera (2) to the vaporized anode gas (5') - Feeding the heated anode gas (5') into a fuel cell (1) [10] Method according to claim 9, wherein ambient heat (Qu) is used for evaporating the liquid anode gas (5). [11] Method according to claim 9 or 10, wherein further heat (Q+) is supplied to the heated anode gas (5") before being fed into the fuel cell (1).

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