Air-cooled fuel cell system

Abstract

The present invention relates to an air-cooled fuel cell system, and aims to provide an air-cooled fuel cell system that increases the usable output range of the fuel cell system by cooling the fuel cell stack using an efficient air cooling method.

Description

Technology Field

[0001] The present invention relates to an air-cooled fuel cell system, and more specifically, to an air-cooled fuel cell system for efficiently cooling a fuel cell stack. Background Technology

[0003] A fuel cell system is a type of power generation system that directly converts the chemical energy contained in fuel into electrical energy electrochemically within the fuel cell stack, without converting it into heat through combustion.

[0004] A fuel cell system is largely composed of a fuel cell stack that generates electrical energy, a hydrogen supply unit that supplies hydrogen as fuel to the fuel cell stack, an air (oxygen) supply unit that supplies oxygen from the air as an oxidant necessary for the electrochemical reaction in the fuel cell stack, a Thermal Management System (TMS) that removes reaction heat from the fuel cell stack to the outside, controls the operating temperature of the fuel cell stack, and performs water management functions, and a fuel cell system controller that controls the overall operation of the fuel cell system.

[0005] With this configuration, the fuel cell system generates electricity by reacting hydrogen, the fuel, with oxygen from the air, and releases heat and water as reaction byproducts.

[0006] Among fuel cells, the Proton Exchange Membrane Fuel Cell (or Polymer Electrolyte Membrane Fuel Cell, PEMFC) is one that possesses high power density.

[0007] In ion exchange membrane fuel cells, the fuel cell stack utilizes a Membrane Electrode Assembly (MEA) in which electrode / catalyst layers where electrochemical reactions occur are attached to both sides of a polymer electrolyte membrane through which hydrogen ions move. In such a fuel cell stack, electricity is generated through an electrochemical reaction when hydrogen is supplied to the anode (also called the 'fuel electrode') and oxygen (air) is supplied to the cathode (also called the 'air electrode' or 'oxygen electrode').

[0008] Meanwhile, the temperature of the membrane used in the fuel cell stack rises due to the heat of the electrode reaction during stack operation, and since this temperature rise causes membrane damage and durability degradation, a cooling device is required to suppress the membrane temperature from rising above a certain temperature.

[0009] Figure 7 attached illustrates a water-cooled fuel cell system, and Figure 8 illustrates an air-cooled fuel cell system.

[0010] In the case of a water-cooled fuel cell system, as the fuel cell stack (10) is cooled using coolant, additional parts such as a coolant reservoir (20), a pump (30), and a radiator (40) are required as shown in FIG. 7, whereas in the case of an air-cooled fuel cell system, as the fuel cell stack (10) is cooled using external air, no additional parts are required and the system configuration is simple as shown in FIG. 8.

[0011] Since air has a lower specific heat than water, the cooling capacity of air-cooling is inevitably smaller compared to water-cooling. Consequently, air-cooling is primarily used in fuel cell systems that do not require high power output, such as small transportation devices like drones or motorcycles, where packaging space is limited.

[0012] Fuel cells require a large amount of heat dissipation because the membrane temperature limit for smooth performance is low at around 100°C. Therefore, when an air cooling method is applied, there is a problem in that their use is limited under high-output conditions. The problem to be solved

[0014] The present invention has been devised in consideration of the above points, and aims to provide an air-cooled fuel cell system that increases the usable output range of the fuel cell system by cooling the fuel cell stack using an efficient air-cooling method. means of solving the problem

[0016] Accordingly, the present invention provides an air-cooled fuel cell system in which condensate is generated as a reaction byproduct when electricity is generated by reacting hydrogen supplied to a fuel cell stack with air, comprising: a cooling pipe disposed through the interior of the fuel cell stack and having an inlet portion protruding to the exterior of the fuel cell stack; a venturi portion formed to have a relatively small inner diameter at the inlet portion of the cooling pipe; a condensate reservoir for storing condensate discharged from the fuel cell stack; a condensate supply pipe having one end connected to the venturi portion and the other end connected to the condensate reservoir; and a drain valve disposed between the condensate reservoir and the condensate supply pipe, which controls the flow of condensate moving from the condensate reservoir to the condensate supply pipe due to a pressure difference between the condensate reservoir and the venturi portion.

[0017] The above air-cooled fuel cell system includes a water trap that collects condensate discharged along with drain gas from the fuel cell stack, and the condensate reservoir is connected to the water trap through the drain valve to store the condensate discharged from the water trap.

[0018] The drain valve comprises: a valve case formed such that a supply pipe communication hole for communicating the condensate supply pipe and the condensate reservoir, and a water trap communication hole for communicating the water trap and the condensate reservoir are arranged in the direction of movement of the valve stem; and a valve stem assembled to be linearly movable within the valve case, having a supply pipe stem hole for opening the supply pipe communication hole and a water trap opening end for opening the water trap communication hole; wherein the supply pipe stem hole and the water trap opening end are arranged at a predetermined interval based on the direction of movement of the valve stem, and the valve stem is configured to selectively open one of the supply pipe communication hole and the water trap communication hole according to its direction of movement.

[0019] In addition, the valve case is provided with an exhaust pipe communication hole positioned between the water trap communication hole and the supply pipe communication hole to communicate between the drain gas exhaust pipe and the condensate reservoir, and the valve stem is provided with an exhaust pipe stem hole positioned between the water trap opening end and the supply pipe stem hole to open the exhaust pipe communication hole, and the exhaust pipe stem hole is characterized by opening the exhaust pipe communication hole when the water trap opening end opens the water trap communication hole.

[0020] In addition, the valve case is positioned between the water trap communication hole and the exhaust pipe communication hole and is provided with an inlet communication hole for communicating the upstream side of the cooling pipe inlet and the condensate reservoir, and the inlet communication hole is characterized by being opened by the exhaust pipe stem hole when the supply pipe stem hole opens the supply pipe communication hole.

[0021] In addition, at one end of the condensate supply pipe connected to the venturi section, a mesh member for splashing condensate moving from the condensate reservoir to the venturi section through the condensate supply pipe may be further provided.

[0022] Meanwhile, according to another embodiment of the present invention, a branch line branched from the air supply line of a fuel cell stack may be further connected to the inlet portion of the cooling pipe, and a branch valve may be further installed in the air supply line to control the flow of air moving to the inlet portion through the branch line.

[0023] In addition, a refill reservoir capable of replenishing liquid water from the outside may be further connected to and installed in the above-mentioned condensate reservoir. Effects of the invention

[0025] According to the means for solving the above-mentioned problem, the air-cooled fuel cell system according to the present invention has the following advantages.

[0026] First, by adopting an air cooling system that has a simpler configuration compared to a water cooling system and offers improved cooling performance compared to existing systems, the usable output range of the fuel cell system can be increased.

[0027] Second, as the output of the fuel cell stack increases, the amount of condensate discharged by the reaction in the stack also increases, so as a result, it is possible to efficiently respond to the system cooling requirements resulting from the increase in the output of the stack.

[0028] Third, by vaporizing and discharging the liquid condensate of the fuel cell stack that is discarded externally, the splashing phenomenon caused by conventional externally discharged condensate can be improved, thereby enhancing marketability. Brief explanation of the drawing

[0030] FIG. 1 is a schematic diagram showing the configuration of an air-cooled fuel cell system according to the present invention. FIG. 2 is a drawing showing the detailed configuration of an air-cooled fuel cell system according to the present invention. FIG. 3 is a drawing showing the operating state of the drain valve when storing condensate in the condensate reservoir among the configurations of the air-cooled fuel cell system according to the present invention. FIG. 4 is a drawing showing the operating state of a drain valve when supplying condensate from a condensate reservoir to the cooling pipe of a fuel cell stack in the configuration of an air-cooled fuel cell system according to the present invention. FIG. 5 is a schematic diagram showing an air-cooled fuel cell system according to another embodiment of the present invention. FIG. 6 is a diagram showing a comparison of usable output performance in a fuel cell system according to the present invention. FIG. 7 is a drawing illustrating a conventional water-cooled fuel cell system. FIG. 8 is a drawing illustrating a conventional air-cooled fuel cell system. Specific details for implementing the invention

[0031] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The details depicted in the accompanying drawings are schematic drawings intended to facilitate the explanation of embodiments of the present invention and may differ from the actual implemented form.

[0032] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0034] As illustrated in FIG. 1, the fuel cell stack (100) receives hydrogen as fuel through a hydrogen supply line (2) connected to a hydrogen tank (1) via an ejector (7), and simultaneously receives air through an air supply line (5), and generates electricity through an electrochemical reaction between hydrogen and oxygen in the air, and generates heat and water (condensate) as reaction byproducts.

[0035] In this fuel cell stack (100), hydrogen is supplied to the anode and air is supplied to the cathode. The hydrogen supplied to the anode is converted into hydrogen ions (H₂) by the catalyst of the electrode layer formed on both sides of the electrolyte membrane. + ) and electrons (e -It is decomposed into ), and among them, only hydrogen ions are selectively transferred to the cathode by passing through the electrolyte membrane, which is a cation exchange membrane, and at the same time, electrons are transferred to the cathode through the gas diffusion layer and separator, which are conductors. At the cathode, a reaction occurs in which hydrogen ions and electrons meet oxygen in the air to generate electrical energy and simultaneously produce condensate. After this reaction, the hydrogen remaining in the fuel cell stack (100) is discharged through the hydrogen discharge line (3), and the air is discharged through the air discharge line (6).

[0036] The fuel cell stack (100) is provided with a cooling pipe (110) for cooling the stack in order to suppress the rise in stack temperature caused by the fuel cell reaction as described above.

[0037] The above cooling pipe (110) is positioned to penetrate the interior of the fuel cell stack (100) and has an inlet portion (111) and an outlet portion (112) protruding to the outside of the stack (100).

[0038] The air for cooling the stack (i.e., cooling air) supplied to the cooling pipe (110) through the inlet section (111) cools the stack (100) as it passes through the inside of the stack (100) and is then discharged to the outside of the stack (100) through the outlet section (112).

[0039] The above cooling air is introduced into the inlet section (111) by a natural aspiration method due to the movement of the device equipped with the fuel cell stack (100). For example, the cooling air may be introduced into the inlet section (111) by a natural aspiration method due to the driving of the vehicle.

[0040] In order to increase the stack cooling performance using the above cooling air, liquid water is supplied to the inlet (111) of the cooling pipe (110). The liquid water is vaporized by the heat of the stack (100) within the cooling pipe (110), thereby increasing the stack cooling performance.

[0041] At this time, the liquid water used is the condensate discharged along with hydrogen from the anode of the stack (100) after the fuel cell reaction.

[0042] A water trap (120) is installed and positioned in the hydrogen discharge line (3) of the stack (100) to collect condensate discharged along with drain gas (hydrogen) from the stack (100).

[0043] As illustrated in FIGS. 1 to 3, the condensate collected in the water trap (120) is selectively transferred to the condensate reservoir (140) through the water trap connection line (121), at which time the condensate moves to the condensate reservoir (140) by free fall. That is, the water trap connection line (121) is configured to allow the condensate collected in the water trap (120) to move to the condensate reservoir (140) by free fall.

[0044] The above condensate reservoir (140) stores condensate transferred from the water trap (120) and is connected to the water trap (120) through the water trap connection line (121), and the condensate transferred into the condensate reservoir (140) is selectively supplied to the cooling pipe (110) through the condensate supply pipe (141).

[0045] One end of the above-mentioned condensate supply pipe (141) in the longitudinal direction is connected to the inlet section (111) of the cooling pipe (110), and the other end in the longitudinal direction is connected to the condensate reservoir (140). Specifically, one end of the above-mentioned condensate supply pipe (141) is connected to the venturi section (113) of the inlet section (111) of the cooling pipe (110) so that condensate can flow, and the other end of the above-mentioned condensate supply pipe (141) is connected to the condensate reservoir (140) so that condensate can flow.

[0046] The above-mentioned venturi section (113) is a portion formed to be constricted with a relatively small inner diameter in the straight inlet section (111) of the cooling pipe (110). More specifically, the above-mentioned venturi section (113) is a portion in which the central part in the longitudinal direction of the inlet section (111) is concavely narrowed.

[0047] In the above inlet section (111), the venturi section (113) has a smaller inner diameter compared to the upstream and downstream sides, thereby forming a relatively low pressure (negative pressure) when cooling air flows, and the suction force of the venturi section (113) acts on the condensate supply pipe (141) due to the pressure difference generated accordingly.

[0048] Meanwhile, a drain valve (200) is used to control the movement of condensate between the condensate reservoir (140) and the water trap (120) and the movement of condensate between the condensate reservoir (140) and the condensate supply pipe (141).

[0049] The drain valve (200) is positioned between the condensate reservoir (140) and the condensate supply pipe (141), and is positioned between the condensate reservoir (140) and the water trap connection line (121), and is configured to control the flow of condensate moving from the condensate reservoir (140) to the condensate supply pipe (141) and the flow of condensate moving from the water trap (120) to the condensate reservoir (140).

[0050] That is, the drain valve (200) controls the flow of condensate sucked from the condensate reservoir (140) to the venturi section (113) by the pressure difference between the condensate reservoir (140) and the venturi section (113), while simultaneously controlling the flow of condensate discharged from the water trap (120) to the water trap connection line (121) and moving to the condensate reservoir (140).

[0051] As illustrated in FIGS. 2 to 4, the drain valve (200) comprises a valve case (210) mounted on the top of a condensate reservoir (140) and a valve stem (220) assembled to be linearly movable within the valve case (210).

[0052] The valve case (210) is a sealed case having a supply pipe communication hole (211), an inlet communication hole (212), a water trap communication hole (213), and an exhaust pipe communication hole (214), and is formed so that a valve stem (220) can move in a hermetic state inside it. The valve case (210) may be formed to have a width greater than the width of the valve stem (220), so that the valve stem (220) can move linearly while in close contact with the inner wall surface of the valve case (210). For example, a predetermined gap may exist between the valve case (210) and the valve stem (220) for the linear movement of the valve stem (220), and the width of the valve case (210) may be set to a value greater than the width of the valve stem (220) by the amount of said gap.

[0053] Additionally, as shown in FIG. 2, an O-ring (230) for sealing may be installed on the inner surface of the valve case (210). In this case, the O-ring (230) may be placed at each location to ensure airtightness between the flow paths of condensate and drain gas. It is also possible for the O-ring (230) to be assembled on the outer surface of the valve stem (220) instead of the inner surface of the valve case (210).

[0054] The above communication holes (211, 212, 213, 214) are each formed to penetrate the upper and lower sides of the valve case (210), and at this time, the condensate reservoir (140) is placed in close contact with the lower side of the valve case (210) so as to be able to communicate with the valve case (210) through the communication holes (211, 212, 213, 214).

[0055] The above supply pipe connection hole (211) is for connecting the condensate supply pipe (141) and the condensate reservoir (140), and the condensate supply pipe (141) is connected to the condensate reservoir (140) so that condensate can flow through the supply pipe connection hole (211). The condensate supply pipe (141) may be formed to extend into the interior of the condensate reservoir (140) by penetrating the supply pipe connection hole (211) for smooth condensate suction, and specifically, it may be formed to extend to a certain height close to the bottom surface of the condensate reservoir (140) by penetrating the supply pipe connection hole (211).

[0056] To be more specific, as previously explained, one end of the condensate supply pipe (141) is connected to the inlet (111) of the cooling pipe (110) and the other end is connected to the condensate reservoir (140), and the other end of the condensate supply pipe (141) is connected to the condensate reservoir (140) through the supply pipe communication hole (211) of the valve case (210).

[0057] The above inlet communication hole (212) is intended to communicate the upstream side of the inlet section (111) of the cooling pipe (110) (i.e., the upstream side of the venturi section (113)) with the condensate reservoir (140), and the inlet section (111) of the cooling pipe (110) is connected to the condensate reservoir (140) through the inlet communication hole (212). The above inlet communication hole (212) can be directly communicated to the upstream side of the venturi section (113) through the venturi section pressurizing pipe (114).

[0058] The above water trap communication hole (213) is for communicating the water trap connection line (121), which is connected to the outlet side of the water trap (120), with the condensate reservoir (140). The water trap connection line (121) is connected to the condensate reservoir (140) through the water trap communication hole (213). Condensate flowing into the condensate reservoir (140) through the water trap connection line (121) passes through the water trap communication hole (213) of the valve case (210) and flows into the condensate reservoir (140).

[0059] The above exhaust pipe connection hole (214) is for connecting the drain gas exhaust pipe (130) for discharging drain gas and the condensate reservoir (140), and the drain gas exhaust pipe (130) is connected to the condensate reservoir (140) through the exhaust pipe connection hole (214).

[0060] In order to ensure that the communication holes (211, 212, 213, 214) open and close according to predetermined conditions during linear movement of the valve stem (220), the exhaust pipe communication hole (214) is positioned at a predetermined distance between the water trap communication hole (213) and the supply pipe communication hole (211), and the inlet communication hole (212) is positioned at a predetermined distance between the water trap communication hole (213) and the exhaust pipe communication hole (214).

[0061] At this time, the water trap communication hole (213), the inlet communication hole (212), the exhaust pipe communication hole (214), and the supply pipe communication hole (211) are arranged sequentially in the linear movement direction of the valve stem (220).

[0062] The above valve stem (220) is provided with an opening end (221) for a water trap, a stem hole (222) for a supply pipe, and a stem hole (223) for an exhaust pipe to open and close the communication holes (211, 212, 213, 214) while moving linearly within the valve case (210).

[0063] The above-mentioned opening (221) for the water trap is one end portion of the edge portion of the valve stem (220) in the linear movement direction of the valve stem (220), and as shown in FIG. 3, when the valve stem (220) moves linearly a predetermined distance in a predetermined direction (i.e., the first direction), the water trap communication hole (213) is opened.

[0064] In addition, in the embodiment illustrated in FIGS. 2 to 4, the water trap opening end (221) is applied as one end of the valve stem (220), but in other embodiments, it is also possible to apply the water trap opening end (221) by changing it into a hole shape. In other words, in order to open the water trap communication hole (213), the valve stem (220) may be provided with a water trap opening hole (not shown) instead of a water trap opening end (221).

[0065] The above-mentioned exhaust pipe stem hole (223) opens the exhaust pipe communication hole (214) according to the linear movement position of the valve stem (220), and is positioned at a predetermined distance from the water trap opening end (221), and as shown in FIG. 3, when the valve stem (220) moves linearly a predetermined distance in the first direction, it matches with the exhaust pipe communication hole (214) and opens the exhaust pipe communication hole (214).

[0066] Specifically, the above-mentioned exhaust pipe stem hole (223) opens the exhaust pipe communication hole (214) when the water trap opening end (221) opens the water trap communication hole (213). Additionally, the above-mentioned water trap opening end (221) opens the water trap communication hole (213) when one side wall surface (i.e., the first side wall surface) of the valve stem (220) comes into close contact with the inner wall surface of the valve case (210).

[0067] When the above water trap communication hole (213) is opened, not only condensate but also drain gas discharged from the fuel cell stack (100) can be introduced into the condensate reservoir (140). Therefore, it is preferable to discharge the drain gas through the drain gas exhaust pipe (130) by opening the exhaust pipe communication hole (214) together with the above water trap communication hole (213). At this time, the drain gas can be naturally discharged by the internal pressure of the condensate reservoir (140).

[0068] The above-mentioned supply pipe stem hole (222) opens the supply pipe communication hole (211) according to the linear movement position of the valve stem (220), and is arranged at a predetermined distance from the water trap opening end (221) based on the movement direction of the valve stem (220). As shown in FIG. 4, when the valve stem (220) moves linearly a predetermined distance in the second direction, it matches with the supply pipe communication hole (211) and opens the supply pipe communication hole (211). The second direction is the opposite direction of the first direction.

[0069] Specifically, the supply pipe stem hole (222) opens the supply pipe communication hole (211) when the other side wall surface (i.e., the second side wall surface) of the valve stem (220) is in close contact with the inner wall surface of the valve case (210), and at this time, the inlet communication hole (212) of the valve case (210) is opened by matching with the exhaust pipe stem hole (223).

[0070] When the valve stem (220) opens the supply pipe communication hole (211), the condensate reservoir (140) is sealed by the drain valve (200), except for the supply pipe communication hole (211) for condensate discharge, so the condensate stored in the condensate reservoir (140) can be smoothly sucked into and moved to the venturi section (113) of the cooling pipe (110) by opening the inlet communication hole (212).

[0071] Here, the first side wall surface of the valve stem (220) is a side wall surface positioned opposite the opening end (221) for the water trap in the linear direction of movement of the valve stem (220), and the second side wall surface of the valve stem (220) is a side wall surface positioned opposite the first side wall surface in the linear direction of movement of the valve stem (220).

[0072] In addition, the valve stem (220) can move linearly within the valve case (210) by means of an actuator (not shown) that supplies linear movement force, and the actuator can be controlled by a fuel cell system controller that controls the overall operation of the fuel cell system.

[0073] The drain valve (200) configured as described above selectively opens one of the supply pipe communication hole (211) and the water trap communication hole (213) of the valve case (210) by controlling the direction of movement and distance of movement of the valve stem (220) by individually establishing a condensate flow path when the condensate reservoir (140) receives condensate into the water trap (120) through the water trap connection line (121) and a condensate flow path when the condensate within the condensate reservoir (140) is supplied to the cooling pipe (110) through the condensate supply pipe (141).

[0074] That is, the drain valve (200) closes the supply pipe communication hole (211) while opening the water trap communication hole (213) when the valve stem (220) moves in the first direction (see FIG. 3), and closes the supply pipe communication hole (211) while closing the water trap communication hole (213) when the valve stem (220) moves in the second direction (see FIG. 4).

[0075] The condensate supplied to the cooling pipe (110) by passing through the drain valve (200) absorbs heat from the stack (100) as it passes through the cooling pipe (110) together with the cooling air introduced through the inlet (111) of the cooling pipe (110), and the air that has absorbed heat from the stack (100) can be discharged to the outside through the outlet (112) of the cooling pipe (110) together with the condensate vaporized by the heat of the stack.

[0076] Meanwhile, as shown in FIG. 2, a mesh member (142) for spraying condensate may be further provided at one end of the condensate supply pipe (141) connected to the venturi section (113) of the cooling pipe (110).

[0077] The condensate discharged to the venturi section (113) by the differential pressure between the condensate supply pipe (141) and the venturi section (113) is rapidly discharged to the venturi section (113) and comes into contact with the mesh member (142), thereby causing the condensate to splatter.

[0078] To be more specific, the mesh member (142) is positioned at one end of the condensate supply pipe (141) to induce atomization of the condensate discharged from the condensate reservoir (140) to the venturi section (113) through the condensate supply pipe (141), thereby increasing the vaporization rate of the condensate passing through the interior of the fuel cell stack (100) through the cooling pipe (110), and consequently, the stack cooling performance can be increased.

[0079] The air-cooled fuel cell system of the present invention configured as described above can efficiently respond to the increased cooling requirements of the stack (100) as the output of the fuel cell stack (100) increases. More specifically, as the output of the fuel cell stack (100) increases, the heat generated by the stack (100) increases, and the cooling requirements of the stack (100) also increase. At the same time, as the output of the stack (100) increases, the reaction amount of the stack (100) increases, and the amount of condensate generated by the reaction in the stack (100) also increases. Accordingly, the amount of condensate supplied to the cooling pipe (110) of the stack (100) also increases, and as a result, it is possible to efficiently respond to the system cooling requirements resulting from the increase in the output of the stack (100).

[0080] Meanwhile, the attached FIG. 5 is a schematic diagram showing an air-cooled fuel cell system according to another embodiment of the present invention.

[0081] As illustrated in FIG. 5, a branch line (150) branched from the air supply line (5) of the fuel cell stack (100) may be further connected to the inlet (111) of the cooling pipe (110), and a branch valve (151) may be further installed in the air supply line (5) at the connection point with the branch line (150) to control the flow of air moving from the air supply line (5) to the branch line (150).

[0082] By connecting the branch line (150) to the inlet (111) of the cooling pipe (110), the cooling pipe (110) can receive air compressed by the air compressor (4) provided in the air supply line (5).

[0083] The opening and closing operation of the branch valve (151) can be controlled to control the flow rate of compressed air supplied to the inlet section (111) through the branch line (150), and the branch valve (151) can be controlled by a fuel cell system controller.

[0084] Specifically, the branch valve (151) can be operated to open when additional cooling air is required to increase stack cooling performance.

[0085] In addition, for cases where an additional liquid water supply is required in addition to the condensate, a refill reservoir (160) capable of refilling and replenishing liquid water from the outside may be connected to the condensate reservoir (140).

[0086] The above refill reservoir (160) can be connected to the condensate reservoir (140) through a flow control valve (161), and liquid water within the refill reservoir (160) can be selectively supplied to the condensate reservoir (140) through the opening and closing control of the flow control valve (161).

[0087] For example, if the amount of condensate stored in the condensate reservoir (140) is insufficient, the flow control valve (161) can be opened to supply liquid water from the refill reservoir (160) to the condensate reservoir (140), and at this time, the liquid water transferred from the refill reservoir (160) to the condensate reservoir (140) is sucked into the venturi section (113) through the condensate supply pipe (141), thereby increasing the stack cooling performance.

[0088] The above refill reservoir (160) may be connected to a condensate reservoir (140) so that the liquid water stored therein is transferred to the condensate reservoir (140) by free fall. This refill reservoir (160) may be a reservoir capable of storing a certain amount of liquid water.

[0089] Figure 6 attached is a graph showing a comparison of the usable output performance in a fuel cell system.

[0090] In the case of small transport devices utilizing conventional air-cooled fuel cell systems, there was a problem in that the usable output was significantly limited due to insufficient cooling performance. However, in the air-cooled fuel cell system of the present invention, condensate that is discarded from the stack is supplied into the stack along with cooling air, and as the condensate vaporizes, it absorbs heat from the stack, thereby increasing the air-cooling performance and, as a result, the usable output range of the fuel cell system can be increased as shown in FIG. 6.

[0091] In addition, by vaporizing the liquid condensate discharged from the fuel cell stack and releasing it externally using the stack's heat, splashing caused by the discharge of liquid condensate can be prevented, and consequently, improved marketability can be expected.

[0093] As embodiments of the present invention have been described in detail above, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Furthermore, since the embodiments described in this specification and the configurations illustrated in the drawings are merely preferred embodiments of the present invention, the scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements by those skilled in the art using the basic concepts of the present invention as defined in the following claims are also included within the scope of the present invention. Explanation of the symbols

[0095] 1 : Hydrogen tank 2 : Hydrogen supply line 3 : Hydrogen emission line 4 : Air compressor 5 : Air supply line 6 : Air exhaust line 7 : Ejector 100: Fuel cell stack 110: Cooling pipe 111: Entrance 112: Exit 113: Venturi section 114: Venturi section pressurized piping 120 : Water trap 121 : Water trap connection line 130: Drain gas exhaust pipe 140: Condensate reservoir 141 : Condensate supply pipe 142 : Mesh member 150 : Branch line 151 : Branch valve 160 : Refill reservoir 161 : Flow control valve 200: Drain valve 210: Valve case 211: Supply pipe connecting hole 212: Inlet vent hole 213: Water trap vent hole 214: Exhaust pipe connection hole 220: Valve stem 221: Open end for water trap 222: Stem hole for supply piping 223 : Exhaust pipe stem hole 230 : O-ring

Claims

Claim 1 A fuel cell system in which condensate is generated as a reaction byproduct when electricity is produced by reacting hydrogen supplied to a fuel cell stack with air, comprising: a cooling pipe disposed through the interior of the fuel cell stack and having an inlet portion protruding to the exterior of the fuel cell stack; a venturi portion formed to have a relatively small inner diameter at the inlet portion of the cooling pipe; a condensate reservoir for storing condensate discharged from the fuel cell stack; a condensate supply pipe, one end of which is connected to the venturi portion and the other end of which is connected to the condensate reservoir; and a drain valve disposed between the condensate reservoir and the condensate supply pipe, which controls the flow of condensate moving from the condensate reservoir to the condensate supply pipe due to a pressure difference between the condensate reservoir and the venturi portion. An air-cooled fuel cell system comprising a water trap for collecting condensate discharged along with drain gas from the fuel cell stack, wherein the drain valve comprises: a valve case formed such that a supply pipe communication hole for communicating the condensate supply pipe and the condensate reservoir, and a water trap communication hole for communicating the water trap and the condensate reservoir are arranged in the direction of movement of the valve stem; and a valve stem assembled to be linearly movable within the valve case, comprising a supply pipe stem hole for opening the supply pipe communication hole and a water trap opening end for opening the water trap communication hole, wherein the supply pipe stem hole and the water trap opening end are arranged at a predetermined interval based on the direction of movement of the valve stem, and the valve stem is configured to selectively open one of the supply pipe communication hole and the water trap communication hole according to the direction of movement. Claim 2 An air-cooled fuel cell system according to claim 1, characterized in that the condensate reservoir is connected to the water trap through the drain valve to store condensate discharged from the water trap. Claim 3 delete Claim 4 An air-cooled fuel cell system according to claim 2, wherein the valve case is provided with an exhaust pipe communication hole disposed between the water trap communication hole and the supply pipe communication hole to communicate between a drain gas exhaust pipe and a condensate reservoir, and the valve stem is disposed between the water trap opening end and the supply pipe stem hole to provide an exhaust pipe stem hole for opening the exhaust pipe communication hole, and the exhaust pipe stem hole opens the exhaust pipe communication hole when the water trap opening end opens the water trap communication hole. Claim 5 An air-cooled fuel cell system according to claim 4, wherein the valve case is disposed between the water trap communication hole and the exhaust pipe communication hole and is provided with an inlet communication hole for communicating the upstream side of the inlet of the cooling pipe and the condensate reservoir, and the inlet communication hole is opened by the exhaust pipe stem hole when the supply pipe stem hole opens the supply pipe communication hole. Claim 6 An air-cooled fuel cell system according to claim 2, characterized in that the condensate supply pipe is formed to extend through the supply pipe communication hole of the valve case to the interior of the condensate reservoir. Claim 7 An air-cooled fuel cell system according to claim 1, characterized in that one end of a condensate supply pipe connected to the venturi section is further provided with a mesh member for atomizing condensate moving from a condensate reservoir to a venturi section through the condensate supply pipe. Claim 8 An air-cooled fuel cell system according to claim 1, wherein a branch line branched from an air supply line of a fuel cell stack is further connected to the inlet portion of the cooling pipe, and a branch valve is further installed in the air supply line to control the flow of air moving to the inlet portion through the branch line. Claim 9 An air-cooled fuel cell system according to claim 1, characterized in that a refill reservoir capable of replenishing liquid water from the outside is further connected to and installed in the condensate reservoir.

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