KR100957365B1 - Humidification and condensation device for fuel cell system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidification and condensation apparatus of a fuel cell system. More particularly, the present invention relates to a humidifier and a condenser function to collect water vapor discharged from an air outlet side of a fuel cell stack for a high temperature / pressurization operation of the fuel cell stack. A humidification and condensation device for an integrated fuel cell system.

To this end, the present invention is a humidification and condensation apparatus of a fuel cell system comprising a fuel cell stack and a humidifier for supplying humidified air to an air electrode of the fuel cell stack, wherein the cooling water is circulated in the humidifier and discharged from the air electrode. A coolant inlet and a coolant outlet formed at a predetermined position of the humidifier to collect water vapor; A closed circulation cooling water line connecting the cooling water inlet and the cooling water outlet; A radiator installed at a cooling water outlet side of the closed circulation cooling water line; A water pump installed at a cooling water inlet side of the closed circulation cooling water line; A humidification and condensation apparatus for a fuel cell system, characterized in that a condensation apparatus composed of a direct installation is provided directly to the humidifier.

Fuel Cell, Humidifier, Condenser, Waste Circulation Cooling Water Line, Water Vapor, Radiator

Description

Humidification and condensation device for fuel cell system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidification and condensation apparatus of a fuel cell system. More particularly, the present invention relates to a humidifier and a condenser function to collect water vapor discharged from an air outlet side of a fuel cell stack for a high temperature / pressurization operation of the fuel cell stack. A humidification and condensation device for an integrated fuel cell system.

A fuel cell, which is a main power supply source of a fuel cell system, is a device that generates electricity while generating water by receiving oxygen in the air and hydrogen as a fuel.

Hydrogen supplied to the fuel cell stack is separated into hydrogen ions and electrons in the catalyst of the cathode electrode (fuel electrode), and the separated hydrogen ions are transferred to the anode (air electrode) through the electrolyte membrane, and subsequently oxygen supplied to the anode (air electrode) Generates electrical energy by combining with electrons entering the anode through an external conductor to generate water.

At this time, the theoretical potential of the fuel cell is 1.23V, and the reaction equation is as follows.

Anode: H ₂ → 2H + + 2e-

Cathode: 1/2 O ₂ + 2H + + 2e- → H ₂ O

In addition, the theoretical potential of the fuel cell stack, that is, hydrogen internal energy is represented by Equation 1 below.

The theoretical potential of the fuel cell stack can rise when the operating pressure and gas utilization increase, and the cause of the stack performance deterioration by the current section when the load increases is dependent on the catalyst layer, the membrane, the gas diffusion layer, and the separator design technology.

For example, as shown in the fuel cell characteristic curve of FIG. 10, which can be expressed by a Tafel equation, as the current density increases, the contact resistance on the cooling surface (euro) of the separator increases, resulting in ohmic polarization ( Resistance loss) tends to increase, resulting in poor output characteristics of the fuel cell or stack.

For reference, the fuel cell voltage is represented by Equation 2 below.

E is hydrogen internal energy.

A, i ₀ : Exchange current density (current density at equilibrium), which indicates activation loss in electrode design / manufacturing.

i _n : Internal current, representing fuel loss in electrolyte membrane design / manufacturing.

i _L : Limit current density, which indicates concentration gradient loss in the design and manufacture of the separator and gas diffusion layer.

r: Resistance loss in electrolyte membrane, separator and gas diffusion layer design / manufacturing.

In the fuel cell vehicle based on this theoretical fact, the technologies required for improving the power density of the fuel cell stack include improvement of membrane and catalyst material properties, increase of reaction area of MEA, increase of operating pressure and operating temperature, gas supply and humidification amount. Increasing the operating temperature of the fuel cell stack requires the development of a membrane capable of securing durability in terms of materials, and the rapid operation temperature rise and the supply gas humidification in the system side are essential.

However, when the operating temperature rises in terms of the entire fuel cell system, the thermal management of the stack is advantageous but disadvantageous in terms of humidification of the humidifier using the exhaust gas due to the rise in temperature of the exhaust gas discharged from the fuel cell.

In other words, high temperature / pressurization operation is required for thermal management and performance improvement of the fuel cell stack. However, when the exhaust gas temperature is increased (near 100 ° C) during high temperature operation (85 ° C or higher), a separate trap for trapping exhaust water vapor at the air outlet side is used. A cooling system is needed.

Therefore, in a high temperature operation, a method of increasing the humidification amount by increasing the operating pressure is possible as a method for overcoming the disadvantage of reducing the supply amount of the humidifier, but in this case, a separate pressurization device is required at the exit of the stack to increase the operating pressure. There is a disadvantage that comes with the spatial constraints of the battery vehicle.

In addition, due to a rise in the temperature of the exhaust gas discharged from the fuel cell during high temperature operation (over 80 ° C), there is a disadvantage that a separate humidifier protection technology is required to prevent deterioration of the material (for example, hollow fiber membrane) in the humidifier. .

In view of this, Korean Patent Registration No. 0644182 discloses a fuel cell power plant having a complicated structure in which a separate condenser is formed at the stack exit side, the condensate is collected in the water tank, and re-supplied to the humidifier. In this case, as the operating temperature of the stack increases, there is a disadvantage that a larger volumetric condensation system configuration is required.

The present invention has been made in view of the above, as a separate inlet and outlet of the cooling water to the humidifier for supplying humidification air to the air electrode, by connecting a radiator between the inlet and outlet of the cooling water, condenser function to the humidifier By integrating, it is possible to easily collect the exhaust water vapor discharged from the air outlet side of the fuel cell stack, to increase the operating pressure of the fuel cell stack, and to prevent the deterioration of the material in the humidifier. Its purpose is to provide a humidification and condensation device for a battery system.

The present invention for achieving the above object is a humidification and condensation apparatus of a fuel cell system comprising a fuel cell stack and a humidifier for supplying humidified air to the cathode of the fuel cell stack, wherein the cooling water is circulated in the humidifier. A humidification and condensation apparatus for a fuel cell system is provided, in which a condenser that collects water vapor discharged from an air electrode is directly installed in the humidifier.

In a preferred embodiment, the condenser includes: a coolant inlet and a coolant outlet formed at a predetermined position of the humidifier; A closed circulation cooling water line connecting the cooling water inlet and the cooling water outlet; A radiator installed at a cooling water outlet side of the closed circulation cooling water line; A water pump installed at a cooling water inlet side of the closed circulation cooling water line; Characterized in that consisting of.

In another preferred embodiment, a thermostat is mounted between the water pump and the coolant inlet section of the waste circulation cooling water line, and a bypass line is connected from the outlet of the thermostat to the section between the radiator and the radiator outlet of the waste circulation cooling water line. It is done.

In another preferred embodiment, the cooling water path of the motor and the cooling water path of the controller are further connected between the water pump and the cooling water inlet of the closed circulation cooling water line.

In addition, the thermostat is mounted between the motor and the coolant inlet section of the waste circulation cooling water line, characterized in that the bypass line is connected to the section between the radiator and the cooling water outlet of the waste circulation cooling water line.

In addition, the size of the pipe to be applied to the air discharge line for exhausting the reaction air from the cathode of the fuel cell stack and the exhaust air inlet of the humidifier connected to the air discharge line to the hot pressurized operating conditions of the fuel cell stack Characterized by the size adopted.

Through the above problem solving means, the present invention can provide the following effects.

1) By directly installing a condenser (cooler) in the humidifier connected to the cathode of the fuel cell stack, it is possible to increase the amount of water vapor trapped in the exhaust gas discharged from the stack gas outlet side during the high temperature operation of the fuel cell stack. .

2) By connecting the cooling water path of the motor and the controller to the closed circulation cooling water line, which is one component of the condenser installed in the humidifier, it is possible to improve the cooling performance of the motor and the controller and increase the space utilization of the vehicle.

3) It is possible to reduce the possibility of MEA deterioration from the thermal cycle of the supply air which may occur when driving a fuel cell vehicle.

4) It is possible to improve the durability of the humidifier by preventing the deterioration of the hollow fiber membrane in the humidifier from the thermal cycle of the exhaust air due to the load fluctuation when applying the high temperature operation system of the fuel cell stack.

5) By adjusting the diameter size of the fuel cell stack inlet / outlet and the connecting pipe of the humidifier connected thereto, it is possible to increase the operating pressure of the fuel cell stack, and separately install a pressurization system on the side of the stack air outlet for pressurized operation. Can be excluded.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In order to help understanding of the present invention, the air supply system of the fuel cell system and its operation will be described below.

The fuel cell system includes a fuel cell stack that generates electrical energy, a fuel supply and recirculation system that supplies and recycles fuel (hydrogen) to the fuel cell stack, and supplies oxygen in the air, which is an oxidant necessary for an electrochemical reaction, to the fuel cell stack. It includes an air supply system, a heat and water management system for controlling the operating temperature of the fuel cell stack, and the like.

As shown in FIG. 9, the air supply system includes an air supply line 14 for supplying air to the cathode 12 of the fuel cell stack 10, and an air discharge line 16 through which the reacted air is discharged. And a humidifier 20 for supplying humidification air to the cathode 12, a blower 18 for supplying fresh external air to be humidified in the humidifier 20, and the like.

Therefore, the wet air containing water from the air discharge line 16 flows into the humidifier 20 and at the same time the external air (dry air) that is sucked from the air blower 18 and passes through the humidifier 20, The humidified air is supplied to the cathode 12 of the fuel cell stack 10.

However, during high temperature operation of the large-area fuel cell stack (coolant inlet temperature 85 ° C.), the exhaust gas temperature emitted from the cathode 12 of the fuel cell stack rises to about 100 ° C. in the high power section, resulting in the exhaust gas (humidifier). Wet air enters into the water vapor state enters the humidifier (20), and the exhaust gas in the water vapor state does not stay in the humidifier 20 for a long time and is easily discharged to the outside with the exhaust air flows into the humidifier (20) The disadvantage is that it does not hydrate the air sufficiently.

Therefore, a separate cooling system for collecting the water vapor contained in the exhaust gas and supplying it to the humidifier is required.

In particular, high temperature / pressurization operation is required for thermal management and performance improvement of the fuel cell stack, and the exhaust gas temperature rise (near 100 ° C) is followed during such high temperature operation (85 ° C. or higher), and thus the air outlet of the fuel cell stack There is a need for a separate cooling system to capture the side vapors of the discharge.

In addition, deterioration of the humidifier material may occur due to discharge steam during high temperature operation (above 80 ° C.), and thus a separate humidifier protection technology is required to prevent deterioration of the humidifier material.

Of course, as shown in the accompanying FIG. 9, after first condensing the discharge gas including water vapor discharged from the fuel cell stack 10 through a condenser disposed independently of the front end of the humidifier 20, the humidifier 20 is used. The amount of exhaust gas collected by the humidifier 20 can be increased by passing through the furnace to the atmosphere, but in this case, a separate condenser 22 must be installed between the fuel cell stack 10 and the humidifier 20. In other words, it occupies a lot of space in the vehicle, so that the spatial constraints are large.

In view of this, the present invention is focused on the integration of the direct condenser function in the humidifier in order to maximize the vapor capture of the exhaust gas discharged from the fuel cell stack.

In other words, a condenser that directly circulates the cooling water in the humidifier and collects the water vapor discharged from the cathode may be installed directly in the humidifier.

Therefore, a cooling system can be configured in the humidifier itself to collect steam discharged from the fuel cell stack to secure the water vapor collection quantity, and the cooling system configured in the humidifier itself can be connected to the cooling system of the motor and controller. Therefore, the space utilization of the vehicle can be greatly increased.

Here, each embodiment of the humidification and condensation apparatus of the fuel cell system according to the present invention will be described.

First embodiment

1 is a block diagram showing a first embodiment of a humidification and condensation apparatus of a fuel cell system according to the present invention.

The cooling water inlet 24 and the cooling water outlet 26 are formed at a predetermined position of the humidifier 20, and the cooling water inlet 24 and the cooling water outlet 26 are connected to the waste circulation cooling water line 30.

In addition, the radiator 28 and the water pump 32 are mounted side by side in the closed circulation cooling water line 30, the radiator 28 is installed adjacent to the cooling water outlet 26, the water pump 32 is cooling water It is installed adjacent to the inlet 24 side.

At this time, as shown in Figures 5 to 7 attached, the humidifier 20 bar can be made in the form of a rectangular housing, or a cylindrical housing, one side of the humidifier 20 is introduced from the air blower (18) An air inlet 34 into which new external air (dry air) is introduced is formed, and on the opposite side, an air outlet 36 for supplying humidified external air to the cathode 12 of the fuel cell stack 10 is provided. In addition, the humidifier 20 is formed with an inlet 38 of exhaust air (gas) discharged from the cathode 12 of the fuel cell stack 10, and an exhaust port 40 is formed on the opposite side thereof. have.

Accordingly, the exhaust gas, that is, the discharge air having water vapor, from the cathode 12 of the fuel cell stack 10 is introduced into the humidifier 20 through the exhaust gas inlet 38 formed in the humidifier 20, and at the same time the cooling water ( Distilled water and antifreeze) are supplied from the radiator 28 to the humidifier 20 through the cooling water inlet 24 by the drive of the water pump 32.

Accordingly, the water vapor is collected by the water due to the cooling action of the cooling water, and at the same time, the hydration of the hollow fiber membrane 42 in the humidifier 20 is made easier, and the dry air introduced by the air blower 18 is made. The humidification effect can be further increased.

Second embodiment

2 is a block diagram showing a second embodiment of the humidification / condensation apparatus of the fuel cell system according to the present invention.

The second embodiment of the present invention includes the same configuration as the first embodiment, and is characterized in that the bypass line 44 and the thermostat 46 are further installed in the closed circulation cooling water line 30.

That is, the thermostat 46 is installed in the section between the water pump 32 and the cooling water inlet 24 in the closed circulation cooling water line 30 section, and the waste circulation cooling water line 30 from the outlet of the thermostat 46. The bypass line 44 is connected to the section between the coolant outlet 26 and the radiator 28 in the section.

The reason why the bypass line 44 and the thermostat 46 are installed in this way is to increase the temperature of the humidifier by using the air that has passed through the air blower during the initial operation and cold start of the fuel cell vehicle.

In other words, since the temperature of the air flowing from the air blower 18 is higher than the temperature of the fuel cell stack 10 at the initial stage of operation of the fuel cell vehicle, the humidifier 20 is used by using the air passing through the air blower 18. Can increase the temperature.

Therefore, it is preferable that the cooling water is not supplied to the humidifier 20 in order to increase the temperature of the humidifier 20. Accordingly, the thermostat 46 is opened at a temperature lower than or equal to the set temperature range of the humidifier 20 so that the cooling water is The pass line 44 flows to the radiator 28 without passing through the humidifier 20.

Third embodiment

3 is a configuration diagram showing a third embodiment of the humidification and condensation apparatus of the fuel cell system according to the present invention.

The third embodiment of the present invention includes the configuration of the first embodiment in the same way, and can only cool the motor and the controller (the driving motor for the actual driving of the fuel cell vehicle and the controller thereof) included in the fuel cell system. One point is to make sure.

That is, the cooling water path of the motor 48 and the cooling water path of the controller 50 are further connected to the section between the water pump 32 and the cooling water inlet 24 in the closed circulation cooling water line 30 section.

Therefore, the coolant is supplied from the radiator 28 to the coolant paths of the motor 48 and the controller 50 by driving the water pump 32, and then cools the motor 48 and the controller 50. , Is circulated into the humidifier (20).

For example, assuming that the coolant temperature in the motor and the controller is maintained at about 65 ° C, and the operating temperature of the fuel cell stack is about 85 ° C, in this case, the relative humidity of the air supplied to the fuel cell stack is about 45 ° C. Can be maintained above the% level.

Fourth embodiment

4 is a configuration diagram showing a fourth embodiment of the humidification / condensation apparatus of the fuel cell system according to the present invention.

The fourth embodiment of the present invention is the same as the configuration of the third embodiment, and is characterized in that the bypass line and the thermostat are installed in the waste circulation cooling water line as in the second embodiment.

That is, the thermostat 46 is installed in the section between the motor 48 and the cooling water inlet 24 in the closed circulation coolant line 30 section, and the closed circulation coolant line 30 section from the outlet of the thermostat 46. The bypass line 44 is connected to the section between the cooling water outlet 26 and the radiator 28.

The bypass line 44 and the thermostat 46 are installed in this way, as described in the second embodiment, by using the air passing through the air blower 18 during the initial operation and cold start of the fuel cell vehicle using a humidifier. This is to increase the temperature of (20).

Therefore, the thermostat 46 is opened at a temperature below the set temperature range of the humidifier 20 so that the coolant flows toward the radiator 28 without passing through the humidifier 20 through the bypass line 44, thereby increasing the temperature of the humidifier. We can raise.

As described in this embodiment, by providing a condensation function to the humidifier, it is possible to increase the amount of humidification even under high temperature and pressurized operating conditions of the fuel cell stack shown in the graph of FIG. 8, and to allow stable operation even at a relatively low humidification condition. Do.

In addition, according to the present invention, when the temperature of the air supplied from the outside rapidly increases to about 100 ° C due to the increase of the rpm of the air blower in the high output section, even if the air passes through the humidifier, the constant temperature is supplied by the cooling water supplied into the humidifier. It is possible to always maintain the temperature, thereby reducing the possibility of deterioration of the electrode film (MEA) due to the thermal cycle (RH cycle) and the RH cycle (thermal cycle) due to the temperature change of the supply air.

In the high temperature operation of the large-area fuel cell stack (coolant inlet temperature 85 ℃), the temperature difference between the stack inlet and outlet occurs more than 0 ~ 10 ℃ according to the load variation, and as a result, in case of membrane humidifier, Although exposed to thermal cycle conditions, particularly in the case of Nafion membrane humidifiers, there is a high possibility of deterioration during thermal cycles and high temperature exposure, but in the present invention, by circulating and supplying cooling water into the humidifier, the hot exhaust gas discharged from the fuel cell stack is discharged. Humidifier can be protected from the durability.

On the other hand, in order to increase the operating pressure of the fuel cell stack, a separate pressurization device is required on the stack exit side.

In the case of hydrogen, it is possible to apply to the specification change of the regulator and the recirculation blower as shown in FIG. 9, but in the case of air, a separate system for pressurization is required on the air outlet side of the fuel cell stack.

Accordingly, in the present invention, the air discharge line 16 through which the reaction air is discharged from the fuel cell stack 10 is discharged, and the discharge air inlet 38 of the humidifier 20 connected to the air discharge line 16. By adjusting the size of the pipe to be applied, in particular to increase the operating pressure of the fuel cell stack by adjusting the diameter of the manifold 52 connected in one module to the exhaust air inlet 38 as shown in FIG. can do.

For example, when the high temperature pressurized operation system of the fuel cell stack is applied, the diameter of the air discharge line 16, the discharge air inlet 38 of the humidifier 20, and the manifold 52 is adjusted to be small. The operating pressure of the battery stack can be increased.

1 is a configuration diagram showing a first embodiment of a humidification / condensation apparatus of a fuel cell system according to the present invention;

2 is a configuration diagram showing a second embodiment of the humidification / condensation apparatus of the fuel cell system according to the present invention;

3 is a configuration diagram showing a third embodiment of the humidification / condensation apparatus of the fuel cell system according to the present invention;

4 is a configuration diagram showing a fourth embodiment of the humidification / condensation apparatus of the fuel cell system according to the present invention;

5 to 7 are schematic views illustrating a structure of a humidification / condensation device of a fuel cell system according to the present invention;

8 is a graph illustrating an operable region of a fuel cell stack;

9 is a configuration diagram illustrating that a humidifier and a condenser of a conventional fuel cell system are separately installed;

10 is a graph showing a fuel cell characteristic curve.

<Explanation of symbols for the main parts of the drawings>

10 fuel cell stack 12 air cathode

14: air supply line 16: air discharge line

18: air blower 20: humidifier

22 condenser 24 cooling water inlet

26: cooling water outlet 28: radiator

30: closed circulation cooling water line 32: water pump

34: air inlet 36: air outlet

38: exhaust air inlet 40: exhaust

42: hollow fiber membrane 44: bypass line

46: thermostat 48: motor

50 controller 52 manifold

54: module

Claims (6)

delete A humidification / condensation apparatus for a fuel cell system, comprising a fuel cell stack and a humidifier for supplying humidified air to an air electrode of the fuel cell stack. The condenser is installed directly in the humidifier to circulate the cooling water in the humidifier to collect the water vapor discharged from the cathode, The condenser is: A coolant inlet and a coolant outlet formed at a predetermined position of the humidifier; A closed circulation cooling water line connecting the cooling water inlet and the cooling water outlet; A radiator installed at a cooling water outlet side of the closed circulation cooling water line; A water pump installed at a cooling water inlet side of the closed circulation cooling water line; Humidification and condensation apparatus of the fuel cell system, characterized in that consisting of. The method according to claim 2, A thermostat is mounted between the water pump and the coolant inlet section of the waste circulation cooling water line, and a bypass line is connected from the outlet of the thermostat to the section between the radiator and the radiator of the cooling water outlet line. Humidification and condensation apparatus. The humidification and condensation system of a fuel cell system according to claim 2, wherein the cooling water path of the motor and the cooling water path of the controller are further connected between the water pump and the cooling water inlet of the closed circulation cooling water line. The method according to claim 2 or 4, Humidification of the fuel cell system, characterized in that the thermostat is mounted between the motor and the coolant inlet section of the waste circulation cooling water line, the bypass line is connected to the section between the radiator and the cooling water outlet of the waste circulation cooling water line. Condensation unit. The method according to claim 2, By adjusting the size of the air discharge line through which the reaction air is discharged from the cathode of the fuel cell stack and the pipe applied to the discharge air inlet of the humidifier connected to the air discharge line, the operating pressure of the fuel cell stack is increased. A humidification and condensation device for a fuel cell system, wherein the fuel cell system can be designed.

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