Fuel cell system with ejector

Abstract

Fuel cell system with an ejector (100) comprising: a stack (210) configured to produce electricity via an electrochemical reaction between fuel and air; a fuel injector (255) arranged to inject fuel into the stack (210); and a water injection nozzle (267) arranged to inject water into the fuel injection nozzle (255), wherein water is supplied to the fuel injector (255) from the water injector (267) due to a vacuum within the fuel injector (255), characterized in that a notch (400) is formed in a fuel injection opening (270) of the fuel injector (255).

Description

BACKGROUND OF THE INVENTION(a) Technical Field

[0001] The present invention relates to a fuel cell system having an ejector that continuously supplies fuel and moisture to a fuel cell stack, which generates electrical energy using the fuel and air to continuously generate electricity. (b) Description of the prior art

[0002] Fuel cell vehicles powered by a fuel cell system often supply hydrogen (as fuel) to a fuel cell stack to generate electrical energy through an electrochemical reaction. This electricity is then used to power an electric motor to propel the vehicle. Such a fuel cell system represents a power generation system that converts electrochemical energy from fuel directly into electrical energy in the fuel cell stack, without converting the fuel's chemical energy into heat through combustion.

[0003] In the fuel cell system, typically high-purity hydrogen is supplied from a hydrogen storage tank to a fuel electrode (anode) of the fuel cell and air from the atmosphere is directly supplied to an air electrode (cathode) of the fuel cell via an air supply device such as an air blower during operation.

[0004] The hydrogen supplied to the fuel cell stack is generally separated into a hydrogen ion and an electron as a catalyst at the fuel electrode (anode). The separated hydrogen ion migrates through a polymer electrolyte membrane toward the air electrode (cathode). Oxygen supplied to the air electrode combines with the electron, which reaches the air electrode through an external conduit, to generate electrical energy while producing water.

[0005] To operate a fuel cell properly, humidity in a membrane electrode assembly (MEB) of the fuel cell stack must be properly maintained, therefore, a humidifier should be provided in each fuel circulation line and air circulation line present in the stack for effective operation of the stack.

[0006] This humidification device / system is traditionally located outside the stack and therefore requires additional space within the vehicle and often complicated piping connections.

[0007] The above information in this background section is provided only to enhance the understanding of the background of the invention and may therefore contain information which does not constitute prior art already known to a person skilled in the art in this country.

[0008] US 2010 0 081 020 A1 describes a fuel cell system and a device for supplying a mixture of fuel and water in this system.

[0009] US 2007 0 238 003 A1 describes a fuel cell system with at least one fuel cell stack and at least one Venturi pump.

[0010] DE 102 23 353 A1 describes a fuel cell system with a polymer electrolyte membrane fuel cell, in particular a water metering arrangement of a fuel cell system. DESCRIPTION OF THE INVENTION

[0011] The present invention is defined by the appended claims and has been made to provide a fuel cell system with an ejector which can reduce the capacity of an external humidifier or avoid a humidifier in the system by continuously reusing moisture generated in an air electrode or a fuel electrode.

[0012] An exemplary embodiment of the present invention provides a fuel cell system with an ejector. More specifically, a stack is provided that generates electricity via an electrochemical reaction between fuel and air, with a fuel injector disposed within the system to inject fuel into the stack. A water injector is also provided within the system for injecting water into the fuel injector. This water can be supplied to the water injector via pressure from the fuel injected by the fuel injector.

[0013] More specifically, a fuel injection hole may be formed in the fuel injection nozzle to receive and inject the fuel. Similarly, a water injection hole of the water injection nozzle may be arranged at a center of the fuel injection hole.

[0014] Furthermore, a water supply line may be connected to the water injection nozzle to supply water contained in a lower portion of a condensate reservoir to the water injection nozzle. The fuel injection nozzle may be disposed in an inlet chamber of the ejector, where the gas circulating in the stack and the fuel are mixed. A notch is formed at the fuel injection port of the fuel injection nozzle.

[0015] The fuel injector may be arranged in the condensate reservoir in which condensate is stored, wherein a main fuel injector, which injects fuel separately from the fuel injector, may be arranged in the inlet chamber of the ejector.

[0016] The fuel injector may be disposed in a collection device adjacent to the stack and a main fuel injector, which injects fuel separately from the fuel injector, may be disposed in the inlet chamber of the ejector.

[0017] The system may further include a water supply line connected to the water injection nozzle for supplying water to the water injection nozzle. The water supply line may be connected to a first condensate reservoir in which moisture from the fuel circulating in the stack accumulates, and a second condensate reservoir in which moisture from the air circulating in the stack accumulates.

[0018] A level sensor may be provided for detecting a level of water contained in the second condensate reservoir, and a water supply control valve may be arranged in a water supply line connecting the second reservoir and the water injection nozzle. Furthermore, a control unit may open the water supply control valve when the control unit determines that the level of water contained in the second reservoir is equal to or higher than a predetermined value.

[0019] The system may further include a fuel control valve that controls the fuel supplied to the fuel injector and a main fuel control valve that controls the fuel supplied to the main fuel injector.

[0020] Advantageously, according to an exemplary embodiment of the present invention, it is possible to reduce the size of an external humidifier or completely remove a humidifier from the fuel cell system by reusing water generated in an air electrode or a fuel electrode. Thus, the required external humidification can be greatly reduced by minimizing or removing water moving from the air electrode to the fuel electrode, while simultaneously controlling the humidity within the fuel electrode. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall layout diagram of a fuel cell system. Fig. 2 is an overall configuration diagram of a fuel cell system with an ejector according to an exemplary embodiment of the present invention. Fig. 3 is a partial detailed cross-sectional view of a fuel cell system with an ejector according to a first exemplary embodiment of the present invention. Fig. 4 is a partial detailed cross-sectional view of a fuel cell system with an ejector according to a second exemplary embodiment of the present invention. Fig. 5 is a schematic configuration diagram of a fuel cell system with an ejector according to a third exemplary embodiment of the present invention. Fig. 6 is a schematic configuration diagram of a fuel cell system with an ejector according to a fourth exemplary embodiment of the present invention. Fig. 7 is a schematic configuration diagram of a fuel cell system with an ejector according to a fifth exemplary embodiment of the present invention. Fig. 8A, Fig. 8B and Fig. 8C are schematic configuration diagrams for illustrating a method of heating hydrogen in the fuel cell system with an ejector according to the exemplary embodiment of the present invention. Fig. 9 is a schematic configuration diagram for illustrating a position of a heat exchanger that heats hydrogen in the fuel cell system with an ejector according to the exemplary embodiment of the present invention. Fig. 10A and Fig. 10B are a plan view and a side view for illustrating a method of assembling the ejector in the fuel cell system with an ejector according to the exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] An exemplary embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] It should be noted that the terms "vehicular" or "vehicle-like" or similar terms, when used herein, refer to motor vehicles in general and include passenger vehicles, including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft, including a variety of boats and ships, aircraft, and the like, including hybrid vehicles, electric vehicles, plug-in hybrid vehicles, hydrogen-powered vehicles, fuel cell vehicles, or other alternative fuel vehicles (e.g., fuels obtained from resources other than oil). A hybrid vehicle, as used in the present disclosure, is a vehicle that has two or more power sources, for example, a gasoline-powered and electric-powered vehicle.

[0023] Furthermore, it should be noted that the following methods are executed by at least one controller. The term controller refers to a hardware device comprising a memory and a processor, and configured to execute one or more steps that are to be interpreted as their algorithmic structure. The memory is configured to store algorithmic steps, and the processor is specifically configured to execute these algorithmic steps to perform one or more processes described below.

[0024] Furthermore, the control logic of the present invention may be embodied as non-transitory computer-readable media on a computer-readable medium comprising executable program instructions executable by a processor, controller, or the like. Examples of the computer-readable medium include, but are not limited to, ROM, RAM, CD-ROM, magnetic tapes, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium may also be distributed in network-coupled computer systems such that computer-readable media are stored and executed in a distributed manner, for example, through a telematics server or a controller area network (CAN).

[0025] Fig. 1 is an overall configuration diagram of a fuel cell system. Referring to Fig. 1, the fuel cell system may include a stack 210 with a cooling channel, a fuel electrode, and an air electrode. The fuel cell system may include a filter 130, a silencer 140, a compressor 150, an intercooler 160, a humidifier 170, and a discharge valve 180 as components that circulate air to the air electrode of the stack 210.

[0026] The fuel cell system may also include a coolant reservoir 105, a radiator 120, and a water pump 110 as components that circulate the coolant to the cooling channel, and an ejector 100, a humidifier 220, a reservoir 202, a purge valve 190, and a drain valve 200 as components that supply hydrogen, which is a fuel, to the fuel electrode.

[0027] In the exemplary embodiment of the present invention, reference is made to the prior art in the detailed description of structures and functions of respective components of the fuel cell system, and a detailed description thereof is omitted. Water is generated from the air electrode in a proton exchange membrane fuel cell (PAMFC) of the stack 210, and the conductivity of an electrode membrane is improved by moisture supplied from the outside. Therefore, forming appropriate moisture on the MEB is essential for proper operation.

[0028] As shown, a humidifier is accommodated in a duct connected to the air electrode, with the humidifier being arranged on a hydrogen supply side to enable reasonable operation. However, a separate arrangement space is required for mounting a separate humidifier, which can complicate the piping. In addition, the humidity (H 2 O) which is generated by the air electrode in the stack 210, is present in a liquid or vapor form depending on the temperature and is transferred to the fuel electrode through a membrane of the air electrode due to a pressure difference.

[0029] The amount of water or vapor in the fuel electrode is varied depending on the driving conditions, and the water and vapor are discharged to the outside through a condensate reservoir or drain valve using a suitable method to reduce hydrogen reaction. Specifically, an unbalanced driving pattern is provided in which the moisture in the air electrode is replenished from the outside, and the moisture is discharged to the outside of the fuel electrode.

[0030] Fig. 2 is an overall configuration diagram of a fuel cell system with an ejector according to an exemplary embodiment of the present invention. Fig. 3 is a partial detailed cross-sectional view of a fuel cell system with an ejector according to a first exemplary embodiment of the present invention.

[0031] Referring to Fig. 2 and Fig. 3, a portion of the fuel cell system may include the stack 210, the condensate reservoir 202, the ejector 100, a fuel injector 255, a mixing tube 280, a water injector 267, a water supply line 265, a heater 260, a pressure sensor 280, and a humidity sensor 282. An inlet chamber 275 is disposed within the ejector 100, with the fuel injector 255 disposed in the inlet chamber 275.

[0032] A fuel injection opening 270 is formed at the end of the fuel injection nozzle 255. The water injection nozzle 267 may be disposed within the fuel injection nozzle 255, and a water injection opening 300 of the water injection nozzle 267 may be disposed at a center of the fuel injection opening 270 of the fuel injection nozzle 255.

[0033] A fuel control valve 250 may be provided in the system to control the flow of hydrogen, which is the fuel supplied to the fuel injector 255, wherein a control unit 10 may be configured to control the fuel control valve 250 according to a drive condition comprising load / pressure / humidity of the stack 210.

[0034] Furthermore, a water supply line 265 may be provided to supply water to the water injection nozzle 267. This water supply line 265 may extend downward into the condensate reservoir 202.

[0035] When the fuel control valve 250 is opened by the control unit 10, hydrogen can be injected from the hydrogen injection port 270 of the fuel injection nozzle 255. At this time, a vacuum is formed by the injected hydrogen. As a result, water is sucked through the water supply line 265 and injected into the fuel injection nozzle 255 from the water injection port 300 of the water injection nozzle 267.

[0036] In the exemplary embodiment of the present invention, the amount of moisture discharged from the fuel cell stack 210 varies due to various factors, including driving temperature, pressure, and the like. For example, the hydrogen injected through the hydrogen injector 255 has a sonic speed (Mach = 1, approximately 1200 m / s), and water is drawn into the fuel injector via the vacuum pressure created by the speed.

[0037] The water injected through the water injection nozzle 267 is atomized by the hydrogen stream to be mixed with the fuel. Furthermore, the supply / mixing efficiency of the fuel and water can be improved by temporarily opening the fuel control valve 250.

[0038] In the exemplary embodiment of the present invention, as a driving load increases, an operating temperature of the stack is increased, an inlet of the fuel electrode is dried, and an amount of discharged water is increased. As described above, the discharged water is recirculated to the fuel electrode to reduce the size of an external humidifier or completely omit the external humidifier.

[0039] Fig. 4 is a partial detail cross-sectional view of a fuel cell system with an ejector according to a second exemplary embodiment of the present invention. A description of similar parts will be given in Fig. 4 in comparison with Fig. 1 to 3 skipped, only the differences are described.

[0040] Referring to Fig. 4, a notch 400 is formed on the fuel injection opening 270 of the fuel injector 255. The notch 400 is formed within the fuel injection opening 300 ( Fig. 3) and an A- or V-shape, thereby increasing the turbulence intensity of the hydrogen injected from the fuel injector 255 to minimize and uniform a particle size and improve mixing of the hydrogen and the recirculated gas.

[0041] In the exemplary embodiment of the present invention, water injection may be suppressed under a low-load condition, and water injection may be performed under a predetermined load or higher. Furthermore, an inner diameter of the water supply line 265 may be controlled, an orifice (not shown) may be formed on the water supply line, or the height of the water supply line 265 may be controlled. Furthermore, a separate control valve (not shown) may be attached to the water supply line 265 to actively control the water injection.

[0042] In addition, a heating device 260 ( Fig. 2) be attached to the mixing pipe 280 of the ejector 100 or the fuel recirculation line, as a result of which low-temperature operation efficiency can be improved by increasing the temperature of the water of an internal circulation line.

[0043] Fig. 5 is a schematic configuration diagram of a fuel cell system with an ejector according to a third embodiment of the present invention. A description of similar parts will be compared with Fig. 1 to 4 in Fig. 5 is skipped, only the differences are described.

[0044] Referring to Fig. 5, the fuel cell system includes the stack 210, the condensate reservoir 202, the ejector 100, the mixing tube 280, and the control unit 10. A main fuel injection nozzle 255a is arranged at the center of the inlet chamber 275 formed in the ejector 100, and the control unit 10 controls a main hydrogen control valve 250a to control the amount of hydrogen injected from the main fuel injection nozzle 255a.

[0045] A fuel injector 255b may be disposed in the condensate reservoir 202, and a water injector 267 may be disposed within the fuel injector 255b. The water supply line 265 may extend such that water contained in the condensate reservoir 202 is supplied to the water injector 267.

[0046] Furthermore, the control unit 10 may be configured to control a hydrogen control valve 250b, which regulates the amount of hydrogen supplied to the fuel injector 255b. Furthermore, the amount of water injected by the water injector 267 may also be controlled according to the amount of hydrogen injected by the fuel injector 255.

[0047] Furthermore, the fuel injector 255b may be inclined to easily supply the fuel and moisture to the ejector 100 from the condensate reservoir 202.

[0048] Fig. 6 is a schematic configuration diagram of a fuel cell system with an ejector according to a fourth exemplary embodiment of the present invention. A description of similar parts to Fig. 1 to 5 will be in Fig. 6 is skipped, only differences are described.

[0049] Referring to Fig. 6, the fuel injector 255a is arranged at a center of the inlet chamber 275 formed in the ejector 100. The control unit 10 may be configured to control the main hydrogen control valve 250a to regulate the amount of hydrogen injected from the main fuel injector 255. Furthermore, a collector 600 may be formed adjacent to the stack 210, and the hydrogen, which is the fuel, may be supplied to the stack 210 through the collector 600.

[0050] The fuel injector 255b may be disposed within the collector 600, and the water injector 267 may be disposed within the fuel injector 255b. The water supply line 265 may extend into the condensate reservoir 202 to supply the water contained in the condensate reservoir 202 to the water injector 267.

[0051] Furthermore, the control unit 10 may be configured to control the hydrogen control valve 250b to regulate the amount of hydrogen supplied to the fuel injector 255b. Furthermore, the amount of water injected by the water injector 267 may also be controlled depending on the amount of hydrogen injected by the fuel injector 255b.

[0052] Fig. 7 is a schematic configuration diagram of a fuel cell system with an ejector according to a fifth exemplary embodiment of the present invention. Fig. 7 is with Fig. 2, only describing differences and skipping similar parts.

[0053] Referring to Fig. 7, the fuel cell system may include an air condensate reservoir 710, a level sensor 720, and a water supply control valve 730. The air condensate reservoir 710 may be a space disposed on an air circulation line connected to the air electrode to condense and collect moisture in the air. The water supply line 265 may supply water collected in a lower portion of the condensate reservoir 202 and water collected in a lower portion of the air condensate reservoir 710 to the water injection nozzle 267. Furthermore, the water supply control valve 730 may regulate the supply of water contained in the air condensate reservoir 710.

[0054] A level sensor 720, which detects the absorbed water, may be arranged in the air-condensate reservoir 710, wherein the control unit 10 may be configured to detect a water level by the level sensor 720 and to control the water supply control valve 730 depending on the detected level.

[0055] That is, the control unit 10 can close the water supply control valve 730 when it determines that the water level contained in the air-condensed water reservoir 710 is below a given value, and the control unit 10 can open the water supply control valve 730 when it determines that the water level is equal to or higher than a set value. Thus, air can be prevented from flowing into a line in which the fuel of the fuel cell is circulated.

[0056] Fig. 8A, Fig. 8B and Fig. 8C are schematic configuration diagrams illustrating a method for heating hydrogen in the fuel cell system with an ejector according to the exemplary embodiment of the present invention.

[0057] Referring to Fig. 8A, the heater 260 may be disposed within a hydrogen line connected to the ejector 100 to heat hydrogen.

[0058] Referring to Fig. 8B, a heat exchanger may be disposed within the hydrogen line connected to the ejector 100, and a coolant and hydrogen pass through the heat exchanger 800, whereby the hydrogen is heated by the coolant.

[0059] Referring to Fig. 8C, a heat exchanger 800 may be disposed within the hydrogen line connected to the ejector 100, wherein condensed water from the humidifier 170 may be discharged through the discharge valve 180, and the discharged condensed water may pass through the heat exchanger 800. The hydrogen may then be heated by the condensed water.

[0060] Fig. 9 is a schematic configuration diagram showing a position of a heat exchanger that heats hydrogen in the fuel cell system with an ejector according to the exemplary embodiment of the present invention. Referring to Fig. 9, the stack 210 is mounted on a front wheel side of a vehicle, and a hydrogen tank 900 is mounted on a rear wheel side. Hydrogen is supplied from the hydrogen tank 900 to the stack 210, with the heat exchanger 800 disposed within a supply line. Air discharged from the stack 210 to the outside may pass through the heat exchanger 800, and the discharged air may heat the hydrogen. Furthermore, the discharged air may pass through the ejector housing 290 to heat the hydrogen passing through the ejector housing 290.

[0061] Fig. 10A and Fig. 10B are a plan view and a side view for illustrating a method of assembling the ejector in the fuel cell system with an ejector according to the exemplary embodiment of the present invention.

[0062] Referring to Fig. 10A and Fig.10B, the ejector 100 may be disposed at an inlet side of a fuel supply header 101, wherein hydrogen is injected from the ejector 100, and a direction in which the hydrogen is injected may coincide with a longitudinal direction of the fuel supply header 101. Furthermore, recirculated combustion gas discharged from a fuel discharge header 102 may be supplied to the ejector 100, and new hydrogen gas may also be supplied to the ejector 100. REFERENCE SYMBOL 10 Control unit 100 ejector 210 stacks 255 Fuel injector 265 Water supply line 267 Water injection nozzle 280 mixing tube

Claims

[1] Fuel cell system with an ejector (100) comprising: a stack (210) configured to produce electricity via an electrochemical reaction between fuel and air; a fuel injector (255) arranged to inject fuel into the stack (210); and a water injection nozzle (267) arranged to inject water into the fuel injection nozzle (255), wherein water is supplied to the fuel injector (255) from the water injector (267) due to a vacuum within the fuel injector (255), characterized by , that a notch (400) is formed in a fuel injection opening (270) of the fuel injection nozzle (255). [2] The system according to claim 1, wherein a fuel injection port (270) which injects the fuel into the stack (210) is formed in the fuel injection nozzle (255), and a water injection port (300) of the water injection nozzle (267) is arranged at a center of the fuel injection port (270). [3] A system according to claim 1 or 2, wherein a water supply line (265) is connected to the water injection nozzle (267) for supplying water contained in a lower portion of a condensate reservoir (202, 710) to the water injection nozzle (267). [4] A system according to any one of claims 1 to 3, wherein the fuel injector (255) is arranged in an inlet chamber (275) of the ejector (100) where gas circulated in the stack (210) and the fuel are mixed together. [5] A system according to any one of the preceding claims, wherein the fuel injector (255) is arranged in a condensate reservoir (202, 710) in which condensate is contained, and a main fuel injector (255) which injects fuel separately from the fuel injector (255) is arranged in the inlet chamber (275) of the ejector (100). [6] A system according to any preceding claim, wherein the fuel injector (255) is disposed in a collection device adjacent to the stack (210), and a main fuel injector (255) which injects fuel separately from the fuel injector (255) is disposed in the inlet chamber (275) of the ejector (100). [7] System according to one of the preceding claims, further comprising: a water supply line (265) connected to the water injection nozzle (267) for supplying water to the water injection nozzle (267), wherein the water supply line (265) is connected to a first condensate reservoir (202) which collects moisture from the fuel circulating in the stack (210) and a second condensate reservoir (710) which collects moisture from the air circulating in the stack (210). [8] The system of claim 7 further comprising: a level sensor (720) configured to detect a level of water contained in the second condensate reservoir (710), and a water supply control valve (730) arranged in a water supply line (265) connecting the second condensate reservoir (710) and the water injection nozzle (267), and a control unit (10) configured to open the water supply control valve (730) when the control unit (10) determines that the level of water contained in the second condensate reservoir (710) is equal to or higher than a predetermined value. [9] System according to one of the preceding claims, further comprising: a fuel control valve (250) which regulates the fuel supplied to the fuel injector (255); and a main fuel control valve (250) which regulates the fuel supplied to the main fuel injector (255). [10] System according to one of the preceding claims, further comprising: a hydrogen line which supplies hydrogen to the fuel injector (255); and a heating device (260) which heats the hydrogen line. [11] System according to one of the preceding claims, further comprising: a hydrogen line which supplies hydrogen to the fuel injector (255); and a heat exchanger (800) which is arranged on the hydrogen line. [12] The system of claim 11, wherein a coolant that cools the stack (210) heats hydrogen passing through the hydrogen line and an ejector housing (290) as it passes through the heat exchanger (800). [13] The system of claim 11 or 12, wherein condensate discharged from circulated air circulated in an air electrode of the stack (210) heats the hydrogen passing through the hydrogen line as it passes through the heat exchanger (800). [14] System according to one of claims 11 to 13, wherein the heat exchanger (800) is arranged between the stack (210) and a hydrogen tank which stores the hydrogen. [15] A system according to any one of the preceding claims, wherein the fuel injector (255) is arranged on an inlet side of the fuel inlet manifold (600) such that the injection directions of the fuel injected by the fuel injector (255) and the water coincide with a longitudinal direction of the fuel inlet manifold (600) of the stack (210).

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