Apparatus for supplying pressurized air to a fuel cell cathode with optimized cooling

Abstract

An apparatus for supplying pressurized air to a cathode (110) of a fuel cell (100) is disclosed, comprising: a compressor (12) connected to an air inlet pipe (14) and an inlet (112) of the cathode, the compressor (12) being configured to receive air originating from the air inlet pipe (14) to compress the air and supply the air to the cathode (110); an electric machine (16) configured to drive the compressor (12) and enclosed by a housing (18); a recuperation turbine (26) configured to expand water-containing air (24) originating from an outlet (114) of the cathode so as to supply the expanded air (28) via an outlet of the turbine (26). The apparatus is characterized in that it comprises a cooling channel (32) configured to receive at least some of the expanded air (28) to cool the housing (18) and the electric machine (16).

Description

Technical Field

[0001] This invention relates to an apparatus for supplying pressurized air to the cathode of a fuel cell. In particular, this invention relates to an optimized cooling apparatus for supplying pressurized air to the cathode of an optimized cooled fuel cell, the optimized cooling apparatus comprising a motorized compressor or a motorized turbocharger, for example, the optimized cooling apparatus can be used in vehicles of the types such as aviation, rail, marine, or automobiles. Background Technology

[0002] Pressurized air supply equipment is used in a variety of scenarios, especially in vehicles, for example, to supply air conditioning systems or fuel cells.

[0003] These pressurized air supply devices typically include motorized compressors, and preferably motorized turbochargers, where the electric motor-driven compressor allows the generation of pressurized air. An important issue mentioned in these devices is the cooling of the motor of the motorized compressor or motorized turbocharger.

[0004] On the one hand, in air conditioning systems, the main issue is ensuring that this cooling does not excessively impact the performance and cost of the air conditioning system, particularly by limiting the use of external cold air removal and / or by not creating additional demand for pressurized air, which would lead to increased energy consumption.

[0005] Today, there is a strong enthusiasm for providing transportation vehicles, especially aircraft, equipped with fuel cells, because these batteries provide a clean, reliable, and flexible energy source.

[0006] The principle behind fuel cells, such as hydrogen fuel cells, is based on the redox reaction between dihydrogen and dioxygen. These two molecules form a chemical fuel, from which energy can be stored in fuel cell applications.

[0007] Therefore, such a fuel cell is a dual-electrode generator, which produces electrical energy, for example, through the oxidation of a reducing fuel such as hydrogen on one electrode and the reduction of an oxidant such as oxygen from the air on the other electrode.

[0008] The redox reaction in a battery not only generates electricity, but also produces byproducts such as water, heat, and deoxygenated air.

[0009] Specifically, the oxidation reaction at the anode decomposes hydrogen molecules in contact with the catalyst, releasing electrons and heat. The reduction reaction at the cathode forms oxygen ions through the contact between oxygen and the electrons released by oxidation. Furthermore, hydrogen protons recombine with oxygen ions to form water.

[0010] The oxygen cathode is supplied, for example, via pressurized air containing enough oxygen to enable the reaction to take place.

[0011] In aviation, rail, marine, or automotive vehicles, pressurized air is supplied by a compressor that is supplied with collected air, for example, collected from the outside via an external air inlet.

[0012] Compressors are typically driven by an electric motor, which is connected to the compressor via a shaft to make the compressor rotate.

[0013] One of the challenges of this device, used to supply pressurized air to the cathode of a fuel cell, is cooling the compressor's drive motor.

[0014] In particular, the motor cooling must be effective enough to allow the power density to be compatible in terms of mass and size with that integrated into airborne systems, especially vehicles such as aircraft.

[0015] In addition, the temperature levels experienced by the components of the pressurized air supply equipment, and especially the air compressor motor, must be controlled to prevent any malfunctions, and these temperature levels must be compatible with the level of reliability required in the airborne system, particularly with the very high level of reliability required in aviation applications.

[0016] The energy consumed by cooling the motor must be kept low so as not to negatively impact the overall efficiency of the system incorporating the motor. These considerations regarding energy and efficiency, in particular, make it possible to control the overall efficiency of the fuel cell and avoid oversized fuel cell systems.

[0017] Finally, efficiency must also be studied at the overall level, especially in terms of quality and complexity, where efficiency must be kept reasonable so as not to affect the overall performance of the vehicle.

[0018] Solutions proposed in the prior art involve cooling the motor through heat exchange with a liquid loop that serves as a radiator. Specifically, in some systems, particularly in the field of motor vehicles, liquid loops have been used to cool other components and are directed towards the motor for cooling. However, implementing such a solution is complex in the absence of a pre-existing liquid loop, and the additional components to be cooled increase the complexity of existing liquid loops and cause a performance degradation.

[0019] Another compressor motor cooling solution involves using collected air for ventilation, which is drawn from either the fuel supply loop or the outside.

[0020] However, in the first case, where air is collected from the fuel supply loop, the air must have already been compressed to benefit from the overpressure that generates the ventilation flow rate. This compression work is consumed in the unused air within the fuel cell and thus adversely affects the overall system efficiency.

[0021] In the second scenario, where air is collected from the outside, the ventilation velocity is typically zero when the vehicle is stationary (especially for aircraft parked on the ground). Fans are used to compensate for this insufficient ventilation, which increases system complexity and reduces energy performance. More generally, the collection of ventilated air leads to a decline in vehicle performance.

[0022] The inventors seek to propose a novel device for supplying pressurized air to a fuel cell, thereby allowing the compressor motor to be properly cooled. Summary of the Invention

[0023] Therefore, the present invention relates to an apparatus for supplying pressurized air to at least one cathode of at least one fuel cell, comprising: -Air inlet pipe, - A compressor, connected to both the air inlet pipe and the cathode inlet, is configured to receive air from the air inlet pipe, compress the air from the air inlet pipe, and supply pressurized air to the cathode. - An electric motor, connected to the compressor via a drive shaft, is configured to drive the compressor and is enclosed in a housing. - An energy recovery turbine is connected to the outlet of the cathode, and the energy recovery turbine is configured to expand water-containing air originating from the outlet of the cathode to supply expanded air via the turbine outlet; the expanded air is referred to as water-containing exhaust air. The device is characterized in that it includes a cooling channel connecting the turbine outlet and the motor housing, the cooling channel being configured to receive at least some of the water-containing exhaust air to cool the motor housing and the motor with this portion of the water-containing exhaust air, wherein the water is in the form of suspended droplets.

[0024] Therefore, the device for supplying the cathode of a fuel cell according to the present invention makes full use of the air leaving the cathode, making it possible to provide efficient and energy-saving cooling for the compressor motor, which is typically intended to be discharged in the prior art.

[0025] The air leaving the cathode initially expands in the energy recovery turbine, which makes it possible to recover energy that can be used in the system, thereby improving overall energy efficiency. Furthermore, the expansion in the turbine lowers the temperature of the water-containing air and causes water present in the air to condense into suspended droplets.

[0026] Therefore, water-containing exhaust air is particularly effective for cooling motor housings and motors. For example, water-containing exhaust air is injected into the cooling circuit on the outer surface of the housing. This exhaust air, which is colder than the motor, cools the motor housing and motor through heat conduction, and the water suspended in the exhaust air will evaporate by absorbing the heat released from the motor and motor housing, thereby improving the cooling of the motor housing and motor.

[0027] Therefore, using water-containing exhaust air makes it possible to cool devices more effectively than existing technologies, or to cool them in the same way using lower airflow rates, which improves the overall energy efficiency of the supply equipment, fuel cells, and vehicles that incorporate supply equipment and fuel cells.

[0028] The supply equipment does not rely on an external system for cooling the compressor motor, and in the case of an aircraft, in particular, the supply equipment can operate autonomously when the aircraft is on the ground.

[0029] Advantageously, and according to the invention, the energy recovery turbine is arranged on the drive shaft.

[0030] According to this aspect of the invention, the compressor, turbine, and motor are connected by a drive shaft, thus forming a motorized turbocharger. Therefore, the energy recovered by the turbine is used to reduce the energy consumption of the motor necessary to drive the compressor, which reduces the heat generated by the motor.

[0031] Advantageously, and according to the invention, the supply device includes a branch arranged between the turbine outlet and the cooling passage, the branch including an inlet configured to receive water-containing exhaust air, and the branch including at least two outlets, a first outlet configured to direct a portion of the water-containing exhaust air to the cooling passage, and a second outlet configured to direct another portion of the water-containing exhaust air to the exhaust outlet of the supply device.

[0032] According to this aspect of the invention, the bifurcation makes it possible to balance the pressure at the turbine outlet; if all the water-containing exhaust air is sent into the cooling passage to cool the motor housing and motor, the resulting pressure drop may reduce the overall performance of the system, especially the turbine performance.

[0033] By allowing a passive balance of flow rates between the cooling channels and the exhaust outlet at the bifurcation, the turbine operates at its maximum performance (the ratio between the pressures at the turbine inlet and outlet is optimized) because the pressure drop downstream of the turbine outlet is optimized and the cooling of the water-containing air is effective, which improves the cooling of the motor and the motor housing.

[0034] Advantageously, and according to the invention, the bifurcation is configured such that most of the water suspended in the water-containing exhaust air is guided to the cooling channel.

[0035] According to this aspect of the invention, the bifurcation optimizes the water distribution in the exhaust air fed into the cooling channel and the directly discharged exhaust air. The presence of water suspended in the exhaust air does not affect the pressure drop performance but rather benefits cooling. Therefore, the bifurcation is configured such that most of the water is transported to the cooling channel. This configuration can be done actively (controlled) or preferably passively (without intervention, which in particular limits energy consumption and system complexity). For example, the bifurcation has a geometry in which a first outlet connected to the cooling channel in the bifurcation is substantially collinear with the direction of the exhaust air flow, so as to guide the water present in the flow primarily toward this outlet, while a second outlet is oriented at a different angle, such that water is preferably guided toward the first outlet.

[0036] Advantageously, and according to the invention, the motor housing includes cooling fins.

[0037] According to this aspect of the invention, the fins enable maximum cooling of the motor and housing. The fins are made of a thermally conductive material to maximize heat exchange.

[0038] According to other variations of the invention, any other device that improves heat exchange can be added to the motor housing.

[0039] Advantageously, and according to the invention, the pressurized air consumer is the cathode of the fuel cell, the inlet of the pressurized air consumer is the inlet of the cathode, and the outlet of the pressurized air consumer is the outlet of the cathode, and the consumed air is water-containing air.

[0040] According to this aspect of the invention, when the pressurized air consumer is the cathode of the fuel cell, the cooling of the motor and motor housing is particularly effective because the air leaving the cathode contains water due to the reaction that occurs in the cathode. Therefore, the apparatus according to the invention for supplying pressurized air to the fuel cell cathode is particularly advantageous for these cooling capabilities of the motor and motor housing, as well as for the autonomy of the apparatus, for example, in vehicles such as aircraft, enabling effective cooling of the motor and motor housing as long as the fuel cell is running, even if the vehicle is stationary (stationary on the ground for an aircraft).

[0041] The present invention also relates to a method for supplying pressurized air to the cathode of a fuel cell, characterized in that the method comprises the following steps: - Air originating from the air inlet pipe is compressed by a compressor driven by an electric motor, and the pressurized air is delivered to the cathode inlet. -Water-containing air originating from the cathode outlet is expanded via an energy recovery turbine. - At least some of the expanded air, referred to as turbine exhaust air, is directed to the housing of the compressor motor to cool the motor housing and the motor. The expanded air carries water in the form of suspended droplets.

[0042] Advantageously, the supply method according to the invention is implemented by the supply equipment according to the invention.

[0043] Advantageously, the supply device according to the invention implements the supply method according to the invention.

[0044] The present invention also relates to a fuel cell system comprising a fuel cell, the fuel cell including a cathode and an anode, characterized in that the fuel cell system includes a device according to the invention for supplying pressurized air to the cathode.

[0045] The present invention also relates to a vehicle comprising a fuel cell, the fuel cell comprising a cathode and an anode, characterized in that the vehicle comprises a device according to the invention for supplying pressurized air to the cathode of the fuel cell.

[0046] Means of transport include, for example, automobiles, aircraft, sea or rail vehicles.

[0047] The present invention also relates to supply equipment, supply methods, fuel cell systems and vehicles, characterized by being composed of all or some of the features mentioned above or below. Attached Figure Description

[0048] Further objects, features, and advantages of the invention will become apparent from the following description, which is provided by way of non-limiting example only, and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of an apparatus for supplying pressurized air to the cathode of a fuel cell according to an embodiment of the present invention. Detailed Implementation

[0049] For the sake of illustration and clarity, the dimensions and proportions in the accompanying drawings are not strictly adhered to.

[0050] Furthermore, the same reference numerals are used throughout the accompanying drawings to denote the same, similar, or analogous elements.

[0051] Figure 1 A supply device 10 is schematically shown, configured to supply pressurized air to the cathode 110 of a fuel cell 100. The fuel cell 100 includes an anode 102 in a known manner, which is supplied with hydrogen via an anode inlet 104 and vents excess hydrogen via an anode outlet 106. The anode 102 is separated from the cathode 110 by a membrane 108.

[0052] The cathode 110 includes a cathode inlet 112 and a cathode outlet 114. The cathode inlet 112 is supplied with pressurized air, and the cathode outlet 114 discharges the residue of the pressurized air after the reaction in the fuel cell 100. The residue forms deoxygenated water-containing air, which is referred to as water-containing air.

[0053] Anode 102 is supplied with hydrogen by a hydrogen supply device (not shown).

[0054] Cathode 110 is supplied with pressurized air, specifically by compressor 12, which is supplied with air via air inlet pipe 14. The air sourced from air inlet pipe 14 is, for example, external air, or air from another system on a vehicle carrying a fuel cell and pressurized air supply equipment 10. For example, in an aircraft, air may be obtained from a propulsion engine or an air conditioning system.

[0055] The compressor 12 is rotated by a motor 16 enclosed by a housing 18. The motor rotates a drive shaft 19 connected to the compressor 12.

[0056] The pressurized air 20 compressed by the compressor 12 is directly transmitted to the cathode 110 of the fuel cell 100, or, as shown in this embodiment, the pressurized air 20 first passes through the heat exchanger 22, thereby forming a heat flow in the heat exchanger 22 to cool the pressurized air 20.

[0057] Pressurized air enters through cathode inlet 112 and then passes through cathode 110. The oxygen in the pressurized air supplies hydrogen to the reaction in the fuel cell to generate electricity.

[0058] Due to the reactions occurring in the fuel cell, the air exiting the cathode via cathode outlet 114 is deoxygenated, water-containing air. In this embodiment, the water-containing air 24 can be used as a cold flow path for the heat exchanger 22 to cool the pressurized air 20.

[0059] The water-containing air 24 is then expanded by the energy recovery turbine 26 of the supply device 10. The energy recovery turbine 26 enables energy recovery from the water-containing air 24 by expanding and cooling it, and by condensing the water into droplets. In this embodiment, the energy recovery turbine 26 is connected to the drive shaft 19 to reduce the energy consumption of the motor 16 when driving the compressor 12. The turbine 26, motor 16, and compressor 12 together form a motorized turbocharger.

[0060] In existing technology, the air leaving the energy recovery turbine is discharged outside after energy recovery.

[0061] In the device for supplying the cathode according to the present invention, the air leaving the turbine—referred to as water-containing exhaust air—is used as a cooling source.

[0062] Specifically, as shown in this embodiment, the water-containing exhaust air 28 leaving the turbine 26 reaches a branch 30. This branch includes an inlet connected to the outlet of the turbine 26 and enables: a portion of the water-containing exhaust air 28 to be directed toward the first outlet toward the cooling passage 32, and another portion of the exhaust air 28 to be directed toward the outside to the first exhaust outlet 34a.

[0063] A portion of the water-containing exhaust air 28 circulating in the cooling channel 32 is guided to the motor housing 18 to cool the motor housing 18 and the motor 16. For cooling purposes, the motor housing 18 may include fins (not shown) or any other means to improve heat exchange. Cooling is improved by evaporating water droplets suspended in the exhaust air 28 guided to the motor housing 18, under the influence of heat generated by the motor 16 driving the compressor 12. After cooling the motor 16 and the motor housing 18, the air is discharged via a second exhaust outlet 34b, which may be different from or connected to the first exhaust outlet 34a to form a single exhaust outlet.

[0064] The branch 30 can be configured such that most of the water present in the exhaust air 28 is directed toward the cooling channel 32.

[0065] The bifurcation 30 allows for passive control of the pressure drop at the cooling passage 32 and the motor housing 18; the pressure at both outlets is ambient pressure, and the pressure at the bifurcation 30 is the same for the portion of the water-containing exhaust air 28 circulating in the branch of the cooling passage 32 and the portion of the exhaust air 28 circulating in the branch leading to the first exhaust outlet 34a, which makes it possible to balance the flow rates between the two branches.

[0066] The supply equipment and fuel cells form a fuel cell system, which can be integrated into automobiles, rail, marine, or air vehicles. In aircraft, the fuel cell system can be integrated into the air conditioning system.

Claims

1. A supply device for supplying pressurized air to at least one cathode (110) of at least one fuel cell (100), comprising: -Air inlet pipe (14). - A compressor (12) is connected to the air inlet pipe (14) and the inlet (112) of the cathode, and is configured to: receive air from the air inlet pipe (14), compress the air from the air inlet pipe (14), and supply pressurized air to the cathode (110). - A motor (16), connected to the compressor (12) via a drive shaft (19), the motor (16) being configured to drive the compressor (12) and enclosed by a housing (18), - An energy recovery turbine (26) is connected to the outlet (114) of the cathode and is configured to: expand water-containing air (24) originating from the outlet (114) of the cathode and condense water present in the water-containing air to form suspended water droplets to supply expanded air via the outlet of the turbine (26), the expanded air being referred to as water-containing exhaust air (28). The supply device is characterized in that it includes a cooling channel (32) connecting the outlet of the turbine (26) and the housing (18) of the motor, the cooling channel (32) being configured to receive at least some of the water-containing exhaust air (28) containing suspended droplets, and to cool the motor housing (18) and the motor (16) with the water-containing exhaust air (28) by evaporating the water droplets in the presence of heat released by the motor (16) and the motor housing (18).

2. The supply equipment according to claim 1, characterized in that, The energy recovery turbine (26) is mounted on the drive shaft (19).

3. The supply equipment according to claim 1 or 2, characterized in that, The supply device includes a branch (30) disposed between the outlet of the turbine (26) and the cooling passage (32), the branch including an inlet configured to receive the water-containing exhaust air (28), and the branch including at least two outlets, a first outlet configured to direct some of the water-containing exhaust air (28) to the cooling passage (32), and a second outlet configured to direct another portion of the water-containing exhaust air (28) to the exhaust outlet (34a) of the supply device.

4. The supply equipment according to claim 3, characterized in that, The branch (30) is configured such that most of the water in the water-containing exhaust air (28) is directed to the cooling channel (32).

5. The supply equipment according to any one of claims 1, 2, and 4, characterized in that, The housing (18) of the motor includes cooling fins.

6. A method for supplying pressurized air to the cathode (110) of a fuel cell (100), characterized in that, The method includes the following steps: - Air originating from the air inlet pipe (14) is compressed by a compressor (12) driven by a motor (16), and pressurized air (20) is delivered to the inlet (112) of the cathode. -Water-containing air (24) originating from the outlet (114) of the cathode is expanded via an energy recovery turbine (26), and water present in the water-containing air is condensed to form suspended water droplets. - At least some of the expanded water-containing air is directed to the housing (18) of the compressor (12) motor, and the motor housing (18) and the motor (16) are cooled by evaporating the water droplets in the presence of heat released by the motor (16) and the motor housing (18). The expanded water-containing air is referred to as the water-containing exhaust air (28) of the turbine containing suspended droplets.

7. A fuel cell system, comprising: A fuel cell (100), comprising a cathode (110) and an anode (102), characterized in that the fuel cell system includes a device (10) for supplying pressurized air to the cathode according to any one of claims 1 to 5.

8. A means of transport, comprising: A fuel cell system comprising a fuel cell (100) including a cathode (110) and an anode (102), characterized in that the vehicle includes a device (10) for supplying pressurized air to the cathode of the fuel cell according to any one of claims 1 to 5.

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