Thermal management system

Abstract

The invention relates to a thermal management system (1, 1a, 1b, 41, 51, 61) comprising a fluid cooling circuit (2) comprising: a cooling channel (3) in a thermal load (4); a cooling pump (5) arranged to circulate a cooling fluid within the fluid cooling circuit (2); and a heat exchanger (6) connected between the cooling channel (3) in the thermal load (4) and the cooling pump (5). The fluid cooling circuit (2) comprises a heat exchanger bypass valve (7) connected to the cooling passage (3) in the thermal load (4) and to the cooling pump (5). The thermal management system (1, 1a, 1b, 41, 51, 61) comprises a ram air passage (8) having a ram air inlet door (9). The ram air passage (8) is arranged to provide cooling to the heat exchanger (6) by ram air cooling when the ram air inlet door (9) is open. The thermal load (4) is an electric motor (13) having at least two associated motor controllers (14) connected in parallel with the electric motor (13). The invention also relates to an electric aircraft (23) comprising a thermal management system.

Description

Technical Field

[0001] The invention relates to a thermal management system comprising a fluid cooling circuit comprising cooling channels arranged in a thermal load to cool the thermal load. The invention also relates to an electric aircraft comprising the thermal management system. Background Art

[0002] All electric equipment generates heat, which needs to be taken care of so that the equipment does not overheat and damage the equipment. Over the past few decades, more and more means of transportation have been switching from fossil fuels to electric propulsion. One of the most recent areas of transportation to switch to electric propulsion is air transportation. Today, efforts are underway to develop electric aircraft that can carry passengers and cargo and replace current fossil fuel-powered aircraft. As with all transportation solutions that rely on electric propulsion, thermal management is important to keep aircraft components in good condition, otherwise these components would be damaged or destroyed due to overheating.

[0003] US2002 / 0180771A1 shows an example of a thermal management system for an electric aircraft. A thermal management system includes a heat source exchanger in thermal communication with an aircraft heat source and a radiator exchanger in thermal communication with a fan airflow path of an electric propulsion engine. A heat distribution bus extends from the heat source exchanger to the radiator exchanger. A control system is operably connected to the thermal management system to selectively thermally couple the radiator exchanger to the heat source exchanger.

[0004] However, the design of a system according to US 2002 / 0180771 A1 in which the fan airflow path of the electric propulsion engine is used to provide cooling for the radiator exchanger may not be flexible and therefore may not provide adequate cooling or, in certain circumstances, may not provide optimal cooling.

[0005] Therefore, there is a need for an improved thermal management system. Summary of the invention

[0006] It is an object of the present disclosure to provide a thermal management system that seeks to mitigate, alleviate or eliminate one or more of the above identified deficiencies and disadvantages in the art, either singly or in any combination.

[0007] The object is achieved by a thermal management system comprising a fluid cooling circuit, the fluid cooling circuit comprising a cooling channel in a thermal load, arranged to cool the thermal load. A cooling pump is arranged to circulate a cooling fluid within the fluid cooling circuit. A heat exchanger is connected between the cooling channel in the thermal load and the cooling pump. The fluid cooling circuit further comprises a heat exchanger bypass valve, the heat exchanger bypass valve being connected to the cooling channel in the thermal load and to the cooling pump, such that the cooling fluid can bypass the heat exchanger when the bypass valve is open. The thermal management system further comprises a ram air channel having a ram air inlet door, wherein the ram air channel is arranged to provide cooling to the heat exchanger by ram air cooling when the ram air inlet door is open.

[0008] An advantage of the thermal management system according to the invention is that it provides an additional source for controlling the temperature of the cooling fluid within the fluid cooling circuit. The thermal management system according to the invention allows for improved control of the thermal management system by having the possibility to bypass the heat exchanger using a heat exchanger bypass valve and having the possibility to increase cooling by opening the ram air inlet door to allow ram air to cool the heat exchanger. The system can also be set up for a variety of different scenarios and can operate over a large range of ambient temperatures.

[0009] The thermal management system may further include a cabin climate circuit, wherein the fluid cooling circuit is arranged to be thermally connected to the cabin climate circuit. The cabin climate circuit may be arranged to utilize heat from a cooling fluid that is heated by heat exchange with a heat load to control the cabin temperature. In order to utilize heat generated by the heat load and carried by the cooling fluid of the fluid cooling circuit, the cabin climate circuit may be thermally connected to the fluid cooling circuit. In this way, heated cooling fluid in the fluid cooling circuit may carry heat to the cabin climate circuit, thereby reducing or eliminating the need for heating the cabin currently used.

[0010] The cabin climate circuit may be fluidly connected to the fluid cooling circuit, or the cabin climate circuit may be arranged to exchange heat with a heated cooling fluid in the fluid cooling circuit. This provides different ways to best transfer heat from the cooling fluid to the cabin climate circuit and provides flexibility in the design of the fluid cooling circuit and the cabin climate circuit.

[0011] The fluid cooling circuit may include a flushing inlet fitting and a flushing outlet fitting, arranged to be connected to a flushing device for flushing the fluid cooling circuit. The cooling fluid in the cooling fluid circuit needs to be replaced regularly. In order to make the replacement of the cooling fluid during maintenance easy and time-saving, the fluid cooling circuit may include a flushing inlet fitting and a flushing outlet fitting, arranged to be connected to a flushing device for flushing the fluid cooling circuit.

[0012] The fluid cooling circuit may include a cooling inlet fitting and a cooling outlet fitting arranged to connect a cooling device for circulating a cooling fluid in the fluid cooling circuit. In certain circumstances, it may be necessary to be able to provide the fluid cooling circuit with a device for circulating a cooling fluid in the fluid cooling circuit. For example, the device is provided when the thermal load generates heat when there is no power to drive a cooling pump of the fluid cooling circuit. This situation may arise when a vehicle including a thermal management system is being charged.

[0013] The thermal loads may be an electric motor and at least one motor controller.A thermal management system according to the present invention arranged to provide cooling to an electric motor and one or more motor controllers provides a versatile system for a variety of applications.

[0014] The cooling channels of the electric motor and the cooling channels of the at least one motor controller may be connected in series or in parallel in the fluid cooling circuit. Depending on the configuration of the electric motor, it may be beneficial to connect the cooling channels of the electric motor and the at least one motor controller in series or in parallel in the fluid cooling circuit. This provides design diversity and the possibility to adjust the flow rate and temperature of the cooling fluid through the electric motor and the motor controller.

[0015] The opening and closing of the ram air inlet door and the opening and closing of the heat exchanger bypass valve may be controlled independently or in conjunction to control the temperature of the cooling fluid. To provide versatile control of the temperature of the cooling fluid, the opening and closing of the heat exchanger bypass valve and the ram air inlet door may be performed independently of each other to better control the temperature of the cooling fluid. For certain applications, the opening and closing of the heat exchanger bypass valve and the ram air inlet door may be linked so that they open and close together according to a preset algorithm. This provides alternative control of the temperature of the cooling fluid.

[0016] The ram air inlet door and the heat exchanger bypass valve may be controlled independently or in conjunction to prevent freezing of the cooling fluid. In one example of temperature control of the cooling fluid, the thermal management system is arranged to prevent freezing of the cooling fluid. Similar to the above, the control of the heat exchanger bypass valve and the ram air inlet door may be controlled independently or in conjunction according to a preset algorithm.

[0017] To prevent freezing of the cooling fluid, the ram air inlet door may reduce the amount of air entering through the ram door by partially or completely closing the ram door, and when the temperature of the cooling fluid is measured to be within five degrees Celsius of its freezing temperature, the heat exchanger bypass valve may at least partially open the bypass valve to allow heated return fluid to recirculate in the cooling circuit.

[0018] The fluid cooling circuit may be arranged to circulate a cooling fluid, which is one or more of the following fluids:

[0019] water,

[0020] Ethylene glycol,

[0021] Silicates,

[0022] Polyalphaolefin (PAO).

[0023] Depending on the amount of heat that the cooling fluid needs to carry in a particular application, a variety of cooling fluids are contemplated. This list should not be considered exhaustive as other cooling fluids may also meet the requirements of one or more applications.

[0024] The invention also relates to an electric aircraft comprising a thermal management system according to the above.An electric aircraft can greatly benefit from a thermal management system according to the invention.

[0025] The cabin climate loop may be an aircraft cabin climate loop. In this way, the electric aircraft may benefit from the heat generated by the thermal load of the thermal management system, so that the aircraft cabin itself requires little or no heating.

[0026] The thermal loads may include batteries arranged in the fuselage of the electric aircraft or in a separate compartment attached to the underside of the fuselage.One example of a thermal load in an electric aircraft that would benefit from a thermal management system according to the invention is the batteries, which generate a lot of heat during use.

[0027] The thermal load may include an electric motor and at least one motor controller arranged in a cabin of the electric aircraft.Another example of a thermal load in an electric aircraft that would benefit from a thermal management system according to the present invention is an electric motor with one or more associated motor controllers that generates significant heat during use.

[0028] The thermal load may include a gas turbine coupled to a generator.

[0029] To extend the range of an electric aircraft, a gas turbine connected to a generator may be a suitable thermal load for a thermal management system. The generator driven by the gas turbine may provide additional power to one or more batteries of the electric aircraft, or to one or more electric motors. In this way, the amount of available power may be increased, allowing the electric aircraft to stay in the air longer.

[0030] The flushing inlet fitting may be arranged in the nacelle, and the flushing outlet fitting may be arranged in the nacelle. This arrangement provides easy accessibility for maintenance personnel to flush the fluid cooling circuit and simplifies the handling of the cooling fluid after flushing to prevent it from spilling.

[0031] A cooling inlet fitting may be arranged in the nacelle and a cooling outlet fitting may be arranged in the nacelle and may be arranged to provide cooling fluid to the fluid cooling circuit when the electric aircraft is on the ground. This arrangement provides easy accessibility for maintenance personnel, thereby simplifying cooling of the aircraft while on the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The foregoing will be apparent from the following more particular description of example embodiments as illustrated in the accompanying drawings in which like reference numerals refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead being placed upon illustrating the example embodiments.

[0033] Figure 1 schematically shows an overview of a first exemplary embodiment of a thermal management system according to the invention,

[0034] Figure 2 schematically shows an overview of a second exemplary embodiment of a thermal management system according to the invention,

[0035] Figure 3a and Figure 3b schematically shows an overview of a third exemplary embodiment of a thermal management system according to the invention,

[0036] Figure 4 schematically shows an overview of a fourth exemplary embodiment of a thermal management system according to the invention,

[0037] Figure 5 schematically shows an overview of a fifth example embodiment of a thermal management system according to the invention,

[0038] Figure 6 schematically shows an overview of a sixth example embodiment of a thermal management system according to the invention,

[0039] Figure 7 An overview of an electric aircraft comprising a thermal management system according to the invention is schematically shown. DETAILED DESCRIPTION

[0040] Aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the apparatus disclosed herein may be implemented in many different forms and should not be construed as limited to the aspects set forth herein. The same numerals in the accompanying drawings refer to the same elements throughout.

[0041] The terms used in this article are only for the purpose of describing certain aspects of the present disclosure and are not intended to limit the present invention.As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0042] The thermal management system according to the present disclosure is intended to solve the problem of providing a good method for controlling the temperature of a cooling fluid in a fluid cooling circuit. In order to solve this problem, the thermal management system of the present disclosure includes a cooling pump, which is arranged to circulate the cooling fluid in the fluid cooling circuit. A heat exchanger is connected between a cooling channel in the heat load and the cooling pump. The fluid cooling circuit further includes a heat exchanger bypass valve, which is connected to the cooling channel in the heat load and to the cooling pump, so that when the bypass valve is opened, the cooling fluid can bypass the heat exchanger.

[0043] Figure 1 The schematic diagram shows an overview of a first exemplary embodiment of a thermal management system 1 according to the invention. The thermal management system 1 comprises a fluid cooling circuit 2 comprising cooling channels 3 in a thermal load 4. Figure 1 , the heat load 4 is outlined to illustrate the layout of the fluid cooling circuit 2. The various components that make up the fluid cooling circuit 2 are known in the art and are not described in detail.

[0044] The cooling channel 3 in the heat load 4 provides a cooling fluid to cool the heat load 4, so that the thermal management system 1 prevents the internal temperature of the heat load 4 from exceeding its maximum acceptable value. The thermal management system 1 further includes a cooling pump 5, which is arranged to circulate the cooling fluid within the fluid cooling circuit 2. A heat exchanger 6 arranged to reduce the temperature of the cooling fluid is connected between the cooling channel 3 in the heat load 4 and the cooling pump 5. The fluid cooling circuit 2 further includes a heat exchanger bypass valve 7, which is connected to the cooling channel 3 in the heat load 4 and to the cooling pump 5, so that when the heat exchanger bypass valve 7 is open, the cooling fluid can bypass the heat exchanger 6. In the case where the temperature of the cooling fluid upstream of the heat exchanger 6 is lower than a predetermined temperature, the heat exchanger 6 can be bypassed. The thermal management system 1 further includes a ram air channel 8, which includes a ram air inlet door 9, wherein the ram air channel 8 is arranged to guide the ram air entering through the ram air inlet door 9 to provide cooling to the heat exchanger 6 by ram air cooling when the ram air inlet door 9 is open.

[0045] The thermal management system 1 further includes a first temperature sensor 10, which is arranged to measure the temperature of the cooling fluid after the cooling fluid leaves the heat exchanger 6 and before the cooling fluid enters the cooling channel 3 of the thermal load 4 (or upstream of the cooling channel 3 of the thermal load 4). The second temperature sensor 11 is arranged to measure the temperature of the cooling fluid after the cooling fluid leaves the cooling channel 3 of the thermal load 4 (or downstream of the cooling channel 3 of the thermal load 4) and before the cooling fluid enters the cooling pump 5. The thermal management system 1 further includes a pressure and temperature sensor 12, which is arranged to measure the pressure and temperature of the cooling fluid after the cooling fluid leaves the cooling pump 5 and before the cooling fluid enters the heat exchanger 6 (or upstream of the heat exchanger 6) or bypasses the heat exchanger 6 and directly enters the cooling channel 3 of the thermal load 4. The pressure and temperature sensor 12 also monitors the status / health of the cooling pump 5. The heat exchanger bypass valve 7 is connected so that the first temperature sensor 10 also measures the temperature of the bypass cooling fluid. In one example, the cooling channel 3 in the thermal load 4 is connected to the rest of the fluid cooling circuit 2 through a cooling port including any suitable accessories.

[0046] The various sensors 10, 11, 12 are connected to a controller such as a motor controller. The controller provides the sensor data to the thermal management system 1 so that the thermal management system 1 controls the temperature of the coolant to a set temperature or temperature range.

[0047] The controller controls the opening and closing of the ram air inlet door 9 and the heat exchanger bypass valve 7 to control the temperature of the cooling fluid. The ram air inlet door 9 and the heat exchanger bypass valve 7 may be controlled independently or jointly. Joint control means that the opening and closing of one of the ram air inlet door 9 and the heat exchanger bypass valve 7 is determined by the opening and closing of the other. Alternatively, each of the ram air inlet door 9 and the heat exchanger bypass valve 7 may be fully opened and closed independently of each other. The ram air inlet door 9 and the bypass valve are operated using suitable actuators electrically connected to the controller, which provides power and opening and closing control signals to the actuators.

[0048] The opening and closing of the ram air inlet door 9 and the heat exchanger bypass valve 7 may be controlled continuously or stepwise.

[0049] In one example of use of the thermal management system 1, the ram air inlet door 9 and the heat exchanger bypass valve 7 are controlled independently or in combination to prevent freezing of the cooling fluid. To prevent freezing of the cooling fluid, the ram air inlet door 9 reduces the amount of air entering through the ram door and passing through the heat exchanger 6 by partially or completely closing the ram air inlet door 9, and when the temperature of the cooling fluid is measured to be within five degrees Celsius of its freezing temperature, the heat exchanger bypass valve 7 is at least partially opened to allow the heated return cooling fluid to recirculate in the cooling fluid circuit.

[0050] The high-level requirement of the thermal management system 1 is to provide automatic control of the cooling fluid flow and temperature of the thermal load 4. The control, monitoring, indication and fault isolation logic of the thermal management system 1 is implemented in the controller. The controller may be provided with one or more auxiliary controllers, wherein the controller and the auxiliary controller have the ability to control, monitor, provide indication and fault isolation for the components of the thermal management system 1. The control logic will define which controller is the "in control" controller for the thermal management system 1 and which controller is the "standby" controller for the thermal management system 1. The thermal management system 1 further controls the cooling fluid flow and temperature of the thermal management system 1 by controlling at least the cooling pump 5, the power supply to the various components of the thermal management system 1 and the thermal load 4. If an auxiliary cooling pump is used, the thermal management system 1 controls the start-up of the cooling pump and the selection between which cooling pump is the active pump or the standby pump.

[0051] The thermal management system 1 is arranged to provide information to the avionics system, including cockpit indication information such as system status, crew alerting system (CAS) status / alert / caution / warning messages and maintenance messages.

[0052] Figure 2 The overview of a second exemplary embodiment of a thermal management system 1a according to the present invention is schematically shown. Figure 2 In the fluid cooling circuit 2, Figure 1 The difference between the fluid cooling circuit in FIG. 1 and FIG. 2 is that the heat load 4 is an electric motor 13 having an associated motor controller 14 connected in series with the electric motor 13. The complete heat load 4 is indicated by the dashed box around the two components. Of course, there can be more than one motor controller 14 connected in series with the electric motor 13.

[0053] The thermal management system 1a controls the cooling fluid temperature based on information provided by at least the following sensors:

[0054] Internal temperature sensor in each motor 13

[0055] Internal temperature sensor in each motor controller 14

[0056] A first temperature sensor 10 upstream of the heat load 4

[0057] Second temperature sensor 11 downstream of heat load 4

[0058] Pressure and temperature sensor 12 upstream of heat exchanger 6

[0059] The motor 13 converts the high voltage power input from the power supply into rotational power. The motor 13 has a self-contained design in the event of a rotor failure and has a fully redundant dual winding design. It is powered by one or more independent motor controllers 14 and converts the high voltage DC power from the battery into high voltage AC power for the motor. The motor 13 includes a device for monitoring motor information (e.g., rotation direction, position, temperature, etc.).

[0060] Figure 3a The overview of a third exemplary embodiment of a thermal management system 1b according to the present invention is schematically shown. Figure 3a In the fluid cooling circuit 2, Figure 2 The fluid cooling circuit in FIG. 2 differs in that the heat load 4 is an electric motor 13 having two associated motor controllers 14 connected in parallel with the electric motor 13. More than two associated motor controllers 14 may be connected in parallel with the electric motor 13. The heat load is indicated by the dashed box around the three components. In this example embodiment, the fluid cooling circuit 2 is provided with a flow balancing device 15, which is arranged before the motor controller 14 so that the flow of the cooling fluid entering the fluid channel of the motor controller 14 can be balanced to provide equal cooling to the two motor controllers 14.

[0061] Alternatively, if Figure 3b As shown in , the motor controllers 14 may be connected in parallel with each other, and the motor controllers 14 are in turn connected in series with the motor 13 . Figure 3b A further alternative shown in FIG. 1 is that the thermal management system 1 b may include an additional heat load 30 in the form of a gas turbine connected to a generator. The cooling channels 3 for the gas turbine and the generator are schematically shown in the figure.

[0062] Figure 4 An overview of a fourth exemplary embodiment of a thermal management system 41 according to the present invention is schematically shown. Figure 4 In the thermal management system 41 and Figure 1 The thermal management system in FIG. 4 is different in that the thermal management system 41 further comprises a cabin climate circuit 16, which comprises a cabin thermally connected to the cabin climate circuit 16. The fluid cooling circuit 12 is arranged to be thermally connected to the cabin climate circuit 16 so that the cabin climate circuit 16 can utilize heat from the cooling fluid heated from the heat exchange with the heat load 4. Thus, the heat from the heat load 4 can be used to control the cabin temperature. Figure 4 In the exemplary embodiment of FIG. 1 , the cabin climate circuit 16 is fluidly connected to the fluid cooling circuit 2 , which means that the cooling fluid is shared between the fluid cooling circuit 2 and the cabin climate cooling circuit.

[0063] Figure 5An overview of a fifth exemplary embodiment of a thermal management system 51 according to the present invention is schematically shown. Figure 5 In the thermal management system 51 and Figure 4 The thermal management system in is different in that the cabin climate circuit 16 comprises a cabin climate heat exchanger 17 which is arranged to exchange heat with the heated cooling fluid in the fluid cooling circuit 2. Alternatively, it is also possible that the cabin climate heat exchanger 17 is part of the fluid cooling circuit 2.

[0064] Figure 6 An overview of a sixth exemplary embodiment of a thermal management system 61 according to the present invention is schematically shown. Figure 6 middle, Figure 1 The fluid cooling circuit 2 is supplemented with a flushing inlet fitting 18 and a flushing outlet fitting 19, which are arranged to connect flushing equipment for flushing the fluid cooling circuit 2. Figure 6 In the figure, a cooling inlet fitting 20 and a cooling outlet fitting 21 arranged to connect a cooling device for circulating a cooling fluid in the fluid cooling circuit 2 are also shown. For the sake of completeness, a fluid circuit drain 22 is also shown, from which the cooling fluid can be drained.

[0065] Depending on the design, the thermal management system may be equipped with both or only one of the two fitting types.The flushing inlet fitting 18, flushing outlet fitting 19, cooling inlet fitting 20 and cooling outlet fitting 21 preferably comprise quick couplers as known in the art.

[0066] It will be appreciated that the fluid cooling circuit 2 and cabin climate circuit 16 of the exemplary embodiment include other suitable components such as secondary cooling pumps and other redundancies, drains, overpressure protection components, filters, accumulators, check valves, etc. For simplicity, these are not shown in the drawings.

[0067] The cooling fluid of the fluid cooling circuit 2 in the exemplary embodiment is one or more of the following fluids:

[0068] water,

[0069] Ethylene glycol,

[0070] Silicates,

[0071] Polyalphaolefin (PAO).

[0072] Figure 7An overview of an electric aircraft 23 including a thermal management system as described above is schematically shown. In this non-limiting example, the electric aircraft 23 comprises a fuselage 24 to which two wings 25 and a tail 26 are attached. Under the wings 25, four nacelles 27 with propellers are mounted, two on each wing 25. An electric motor 13 and at least one motor controller 14 are arranged in each nacelle 27. In order to power the electric motors 13, batteries 28 are arranged in the lower part of the fuselage 24, or alternatively in a separate compartment attached to the underside of the fuselage 24. Each battery 28 is connected to one electric motor 13 via a battery distribution unit connected to an inverter. Figure 7 The placement of the middle battery 13 is exemplary only and is not intended to be limiting.

[0073] The power distribution unit is connected to one or more motor controllers 14, which are connected to the motors 13, thereby controlling the supply of power to the motors 13. Batteries can also be arranged in the two wings 25 and the fuselage 24 of the electric aircraft 23. This is illustrated in dashed lines by the batteries 28 in the fuselage of the aircraft. The motors 13 drive propellers with hydromechanical or electric pitch actuators. The propellers can achieve reverse thrust and feathering. In one example, the propellers on each wing 25 are counter-rotating.

[0074] In the electric aircraft 23, in addition to the battery, the thermal load 4 may include an electric motor 13 and at least one electric motor controller 14 arranged in the cabin 27 of the electric aircraft 23. The thermal load 4 may also include a gas turbine connected to a generator, which is arranged to generate energy to support the battery when providing power to one or more electric motors 13. The gas turbine is arranged to rotate the generator, which in turn provides additional power to the electric motor 13. The gas turbine is connected to the fuel tank and can be operated with any suitable fuel. The generator is electrically connected to the battery distribution unit of each of the four electric motors 13, so as not to be mechanically connected to the propeller. The battery distribution unit can be arranged to provide power directly from the generator to one or more electric motors 13, or to provide power for charging one or more batteries. If necessary, the turbine generator device can extend the range of the electric aircraft 23.

[0075] The thermal load 4 may additionally include one or more of an avionics system thermal load, a cockpit thermal load, or a hydraulic system thermal load.

[0076] The present disclosure relates to a thermal management system including a fluid cooling circuit, the fluid cooling circuit including: a cooling channel in a thermal load, arranged to cool the thermal load; a cooling pump, arranged to circulate a cooling fluid within the fluid cooling circuit; and a heat exchanger, connected between the cooling channel in the thermal load and the cooling pump. The fluid cooling circuit further includes a heat exchanger bypass valve, which is connected to the cooling channel in the thermal load and to the cooling pump, so that when the bypass valve is open, the cooling fluid can bypass the heat exchanger. The thermal management system further includes a ram air channel, which includes a ram air inlet door, wherein the ram air channel is arranged to provide cooling to the heat exchanger through ram air cooling when the ram air inlet door is open. The thermal load is an electric motor having at least two associated motor controllers connected in parallel with the electric motor.

[0077] According to some embodiments, the fluid cooling circuit includes a flow balancing device arranged before the motor controller so that the flow of cooling fluid entering the fluid channels of the motor controller can be balanced to provide equal cooling to the two motor controllers. The flow balancing device may include one or more flow control valves.

[0078] According to some embodiments, in the fluid cooling circuit, the cooling channels of the electric motor and the cooling channels of at least two electric motor controllers are connected in series or in parallel.

[0079] According to some embodiments, the fluid cooling circuit comprises a cooling passage in another heat load, wherein the other heat load comprises a gas turbine connected to a generator.

[0080] According to some embodiments, the fluid cooling circuit comprises a flushing inlet fitting and a flushing outlet fitting arranged to connect flushing equipment for flushing the fluid cooling circuit.

[0081] According to some embodiments, a fluid cooling circuit includes a cooling inlet fitting and a cooling outlet fitting arranged to connect to a cooling device for circulating a cooling fluid in the fluid cooling circuit.

[0082] According to some embodiments, opening and closing of the ram air inlet door and opening and closing of the heat exchanger bypass valve may be controlled independently or in conjunction to control the temperature of the cooling fluid.

[0083] According to some embodiments, the ram air inlet door and the heat exchanger bypass valve are controlled independently or in conjunction to prevent freezing of the cooling fluid. To prevent freezing of the cooling fluid, the ram air inlet door can reduce the amount of air entering through the ram door and passing through the heat exchanger by partially or completely closing the ram air inlet door, and when the temperature of the cooling fluid is measured to be within five degrees Celsius of its freezing temperature, the heat exchanger bypass valve is at least partially opened to allow heated return cooling fluid to recirculate in the cooling fluid circuit.

[0084] According to some embodiments, the fluid cooling circuit is arranged to circulate a cooling fluid, the cooling fluid being one or more of water, ethylene glycol, silicate and polyalphaolefin (PAO).

[0085] The present disclosure also relates to an electric aircraft comprising a thermal management system according to any one of the above features.

[0086] According to some embodiments, the heat load comprises a battery arranged in the fuselage of the electric aircraft or in a separate compartment attached to the underside of the fuselage.

[0087] According to some embodiments, an electric motor and at least two electric motor controllers are arranged in a cabin of an electric aircraft.

[0088] According to some embodiments, the flushing inlet fitting is arranged in the nacelle and the flushing outlet fitting is arranged in the nacelle.

[0089] According to some embodiments, a cooling inlet fitting is arranged in the nacelle and a cooling outlet fitting is arranged in the nacelle, and the cooling inlet fitting and the cooling outlet fitting are arranged to provide cooling fluid to the fluid cooling circuit when the electric aircraft is on the ground. Reference numerals mentioned in the claims shall not be regarded as limiting the scope of what is protected by the claims, and their sole function is to make the claims easier to understand.

[0090] As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the scope of the appended claims.Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0091] Reference numerals:

[0092] 1.1a,1b: Thermal management system

[0093] 2: Fluid cooling circuit

[0094] 3: Cooling channel

[0095] 4: Heat load

[0096] 5: Cooling pump

[0097] 6: Heat exchanger

[0098] 7: Heat exchanger bypass valve

[0099] 8: Ram air channel

[0100] 9: Ram air inlet door

[0101] 10: First temperature sensor

[0102] 11: Second temperature sensor

[0103] 12: Pressure and temperature sensors

[0104] 13: Electric motor

[0105] 14: Motor controller

[0106] 15: Flow balancing device

[0107] 16: Cabin climate circuit

[0108] 17: Cabin climate heat exchanger

[0109] 18: Flush inlet fittings

[0110] 19: Flush outlet fittings

[0111] 20: Cooling inlet accessories

[0112] 21: Cooling outlet accessories

[0113] 22: Fluid circuit drain device

[0114] 23: Electric aircraft

[0115] 24: Body

[0116] 25: Wing

[0117] 26: Tail

[0118] 27: Cabin

[0119] 28: Battery

[0120] 41: Thermal management system with cabin climate circuit

[0121] 51: Thermal management system with cabin climate heat exchanger

[0122] 61: Thermal management system with flushing accessories

Claims

1. A thermal management system (1, 1a, 1b, 41, 51, 61), comprising a fluid cooling circuit (2), the fluid cooling circuit (2) comprising: a cooling channel (3) in the heat load (4), arranged to cool the heat load (4); a cooling pump (5), arranged to circulate the cooling fluid in the fluid cooling circuit (2); and a heat exchanger (6) connected between the cooling channel (3) in the heat load (4) and the cooling pump (5), wherein the fluid cooling circuit (2) further comprises a heat exchanger bypass valve (7) connected to the cooling channel (3) in the heat load (4) and to the cooling pump (5) so that when the bypass valve is open, the cooling fluid can bypass the heat exchanger (6), wherein the thermal management system (1, 1a, 1b, 41, 51, 61) further comprises a ram air channel (8) having a ram air inlet door (9), wherein the ram air channel (8) is arranged to provide cooling to the heat exchanger (6) by ram air cooling when the ram air inlet door (9) is open, characterized in that the heat load (4) is an electric motor (13) having at least two associated motor controllers (14) connected in parallel with the electric motor (13).

2. A thermal management system according to claim 1, wherein the fluid cooling circuit (2) includes a flow balancing device (15), which is arranged before the motor controller (14) so ​​that the flow of the cooling fluid entering the fluid channel of the motor controller (14) can be balanced to provide equal cooling to the two motor controllers (14). 3 . The thermal management system of claim 2 , wherein the flow balancing device comprises one or more flow control valves.

4. The thermal management system according to any one of claims 1 to 3, wherein the cooling channel (3) of the electric motor (13) and the cooling channels (3) of the at least two electric motor controllers (14) are connected in series or in parallel in the fluid cooling circuit (2).

5. The thermal management system according to any one of claims 1 to 4, wherein the fluid cooling circuit (2) comprises a cooling channel (3) in another thermal load (4), wherein the other thermal load (4) comprises a gas turbine connected to a generator.

6. A thermal management system according to any one of the preceding claims, wherein the fluid cooling circuit (2) comprises a flushing inlet fitting (18) and a flushing outlet fitting (19), the flushing inlet fitting (18) and the flushing outlet fitting (19) being arranged to connect flushing equipment for flushing the fluid cooling circuit (2).

7. A thermal management system according to any one of the preceding claims, wherein the fluid cooling circuit (2) comprises a cooling inlet fitting (20) and a cooling outlet fitting (21), the cooling inlet fitting (20) and the cooling outlet fitting (21) being arranged to connect a cooling device for circulating a cooling fluid in the fluid cooling circuit.

8. The thermal management system according to any one of the preceding claims, wherein opening and closing of the ram air inlet door (9) and opening and closing of the heat exchanger bypass valve (7) are controlled independently or jointly to control the temperature of the cooling fluid.

9. The thermal management system according to claim 8, wherein the ram air inlet door (9) and the heat exchanger bypass valve (7) are controlled independently or jointly to prevent freezing of the cooling fluid.

10. A thermal management system according to claim 9, wherein to prevent freezing of the cooling fluid, the ram air inlet door (9) reduces the amount of air entering through the ram door and passing through the heat exchanger (6) by partially or completely closing the ram air inlet door (9), and when the temperature of the cooling fluid is measured to be within five degrees Celsius of its freezing temperature, the heat exchanger bypass valve (7) is at least partially opened to allow heated return cooling fluid to recirculate in the cooling fluid circuit.

11. The thermal management system according to any of the preceding claims, wherein the fluid cooling circuit (2) is arranged to circulate a cooling fluid, the cooling fluid being one or more of the following fluids: water, Ethylene glycol, Silicates, Polyalphaolefin (PAO).

12. An electric aircraft (23) comprising a thermal management system (1, 1a, 1b, 41, 51, 61) according to any one of claims 1 to 11.

13. The electric aircraft according to claim 12, wherein the heat load (4) comprises a battery (28), the battery (28) being arranged in the fuselage (24) of the electric aircraft (23) or in a separate compartment attached to the underside of the fuselage (24).

14. The electric aircraft according to any one of claims 12 or 13, wherein the electric motor (13) and the at least two electric motor controllers (14) are arranged in a cabin (27) of the electric aircraft (23).

15. The electric aircraft according to any one of claims 12 to 14, wherein the flushing inlet fitting (18) is arranged in the nacelle (27) and the flushing outlet fitting (19) is arranged in the nacelle (27).

16. The electric aircraft according to any one of claims 12 to 15, wherein the cooling inlet fitting (20) is arranged in the nacelle (27), and the cooling outlet fitting (21) is arranged in the nacelle (27) and is arranged to provide cooling fluid to the fluid cooling circuit (2) when the electric aircraft (23) is on the ground.

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