KR20210044764A - Hydrogen supplysystem for fuelcellin automobile - Google Patents

Abstract

The present invention relates to a fuel cell used in a vehicle, and more specifically, has been proposed for an object of increasing the efficiency of a fuel cell. In the configuration, a regulator controls the pressure of hydrogen in a fuel tank. An ejector supplies the pressure-controlled hydrogen to a stack. A heat exchanger is installed between the fuel tank and the ejector to exchange heat between the hydrogen supplied through a hydrogen supply line for supplying hydrogen and cooling water discharged from the stack. Excess hydrogen of exhaust gas discharged from the stack through a recirculation line is circulated to the ejector. A control unit comprises: a sensitive heat tube installed to surround the outer periphery of the hydrogen supply line and accommodating a working fluid; and a pressure reducing valve operating as an actuator according to the pressure of the working fluid accommodated in the sensitive heat tube to control the amount of the cooling water supplied to the heat exchanger. A communication pipe communicates between the sensitive heat tube and the pressure reducing valve and is fixed in contact with a cooling water input line. Above the cooling water input line in the longitudinal direction, a communication pipe fitting bracket (46a) perforated to fit and fix the circumference of the body of the communication pipe is vertically configured (b2), and the outer peripheral body of the communication pipe is coupled thereto. The end of the communication pipe is bent (b3) at a right angle to be aligned (b1) along the length of the cooling water input line, and the direction thereof is changed from vertical (b2) to horizontal (b1). An open balun inlet (80a) of a balun is closely attached to the end (63a) of the communication pipe, which is provided by being bent (b3).

Description

Hydrogen supply system for fuelcellin automobile

The present invention relates to a hydrogen supply device for a fuel cell for a vehicle in which the efficiency of fuel cells is improved by controlling the temperature of hydrogen gas flowing from a hydrogen tank.

Fuel cells used in automobiles are a means of directly converting chemical energy generated by oxidation of fuel into electrical energy. Unlike a secondary battery, a fuel cell continuously supplies reactants from the outside and simultaneously discharges reaction products to the outside of the system. Therefore, continuous electricity generation is possible if fuel is continuously supplied. In the most widely used hydrogen-oxygen fuel cell, hydrogen, a fuel, is supplied to the cathode to cause electrical oxidation, and oxygen, an oxidizing agent, is supplied to the anode to cause electrical reduction. As electrons move through oxidation and reduction, electric energy is generated. Since the electric energy generated from a unit cell is insignificant, a fuel cell is provided in the form of a stack in which tens to hundreds of unit cells are stacked. As for the fuel cell capacity, if the number of stacks in the stack is increased, a large-capacity fuel cell of hundreds of MW is possible. Fuel cells are widely used for power generation, heating, and transportation.

A hydrogen supply system for a fuel cell for a vehicle, as in Registered Patent No.836371 (2008.6.20.) shown in FIG. 1,

Hydrogen charged at high pressure in the fuel tank 112 is regulated to a constant pressure through the high pressure regulator 114 and regulated to a pressure that can be supplied to the stack 110 through the low pressure regulator 116. Here, a solenoid valve 118 is installed between the high pressure regulator 114 and the low pressure regulator 116 to control the flow of hydrogen. In addition, since the hydrogen supplied to the stack 110 supplies a greater amount than the amount required for the reaction in order to increase the efficiency, the exhaust gas contains not only water vapor, but also a considerable amount of hydrogen. The hydrogen recycle line 122 branched from is formed. In addition, a blower 124 is installed in the hydrogen recycling line 122 so that the recycled hydrogen gas is easily circulated to the stack 110. In addition, although the blower 124 needs power to rotate, an ejector that does not require power may be installed if necessary. Here, when the ejector is installed, the gas supplied from the fuel tank 112 and the recirculated gas are mixed and supplied to the stack 110 in the ejector.

On the other hand, when the relative humidity is high, the hydrogen supplied to the stack causes a flooding phenomenon that closes the flow path by generating droplets. When the relative humidity is low, the electrolyte membrane is dried as the humidity of the electrode decreases, preventing the movement of ions and electrons. A dryout phenomenon that rapidly slows occurs.

Therefore, the relative humidity of hydrogen gas supplied to the stack should be maintained at 80% or more in consideration of efficiency, but should be managed at less than 100%.

However, although the temperature of hydrogen gas discharged from the stack is relatively constant at about 70℃, the temperature of hydrogen supplied from the fuel tank varies depending on the temperature of the atmosphere. Uneasy.

Therefore, in the cold season when the temperature drops to -30℃, if the hydrogen gas discharged from the high-temperature and high-humidity stack and the hydrogen supplied from the fuel tank are immediately mixed, the temperature of the mixed gas not only drops excessively, but also the relative humidity reaches 100%. Since droplets are generated, a heat exchanger was installed to preheat the temperature of hydrogen gas supplied from the fuel tank with waste heat of cooling water discharged from the stack to prevent this.

However, in hot weather, the temperature of hydrogen gas supplied from the fuel tank is already 30℃ or higher, so when preheating with cooling water discharged from the stack, the temperature of the hydrogen gas supplied to the ejector rises to 45℃ or higher, so it is mixed with the hydrogen gas discharged from the stack. In this case, not only the temperature of the gas mixture is excessively increased, but also the relative humidity is reduced to 50% or less, which causes a dry-out phenomenon.

By controlling the amount of cooling water that preheats the hydrogen gas supplied from the fuel tank according to the temperature of the hydrogen gas supplied from the fuel tank, it is possible to easily control the relative humidity of the hydrogen gas supplied to the stack, and thus the relative humidity of the hydrogen electrode. We provide a fuel cell hydrogen supply system that can optimize

Provides a fuel cell hydrogen supply system capable of improving the efficiency of a fuel cell by optimizing the relative humidity of the hydrogen electrode as described above,

It is intended to provide a fuel cell hydrogen supply system that does not require a separate driving unit to control the amount of cooling water by controlling the amount of cooling water with a pressure reducing valve that operates according to the pressure of the working fluid contained in the thermostat.

It is intended to provide a fuel cell hydrogen supply system Å capable of sensitively sensing a temperature change of the hydrogen supply line due to a large heat transfer area since a thermal cylinder surrounding the outer periphery of the hydrogen supply line is provided.

Vehicle hydrogen supply device, a fuel tank in which hydrogen is stored; A regulator controlling the pressure of hydrogen supplied from the fuel tank; An ejector for supplying hydrogen whose pressure is controlled by the regulator to the stack; A heat exchanger installed between the fuel tank and the ejector to exchange heat between hydrogen supplied through a hydrogen supply line supplying hydrogen and cooling water discharged from the stack; A recirculation line for recirculating the gas discharged from the stack and supplying it to an ejector; And a control unit for adjusting the amount of cooling water supplied to the heat exchanger,

The control unit is installed on the hydrogen supply line, the temperature sensing tank for accommodating the working fluid; And a pressure reducing valve that operates according to the pressure of the working fluid accommodated in the thermostat,

The thermal tube is provided to surround the outer periphery of the hydrogen supply line,

The pressure reducing valve includes: a partition wall in which a valve seat having a port formed at an inner center of a cooling water supply line supplying cooling water to the heat exchanger extends in an axial direction; A housing formed on a circumference of a cooling water input line corresponding to the partition wall; A diaphragm that divides the interior of the housing vertically and communicates the divided upper portion and the thermally sensitive tube; An opening/closing member installed on a lower surface of the diaphragm to open and close the port by the operation of the diaphragm; And a spring installed to elastically support the opening and closing member.

Hydrogen supplied from the fuel tank is equipped with a thermal tube surrounding the outer periphery of the hydrogen supply line, so that the temperature change of the hydrogen supply line can be sensitively sensed over a wide heat transfer area, and the amount of cooling water that preheats the hydrogen gas supplied from the fuel tank is supplied from the fuel tank. By adjusting according to the temperature of the gas, the relative humidity of the hydrogen gas supplied to the stack is easily adjusted to optimize the relative humidity of the hydrogen electrode, and the efficiency of the fuel cell is improved by optimizing the relative humidity of the hydrogen electrode. With a pressure reducing valve that operates according to the pressure of the received working fluid, a separate driving unit for controlling the amount of cooling water may not be required by controlling the amount of cooling water.

1 is a block diagram showing a conventional automobile fuel cell hydrogen supply system.
2 is another exemplary view of a conventional fuel cell hydrogen supply system for a vehicle.
3 is a view showing a controller of the vehicle fuel cell hydrogen supply system.
4 is a detailed cross-sectional view showing a main part of the fuel cell hydrogen supply system for an automobile.
5 is a state diagram showing that the pressure reducing valve of the fuel cell effort supply system for a vehicle is opened.
6 and below relate to the present invention. In FIG. 6, FIG. 6A is a cross-sectional view of a certain portion, and FIG. 6B is an exemplary view for explaining the configuration.
7 is a state diagram illustrating an operation. Fig. 7A is in one state, and Fig. 7B is in another state.
8 is an exemplary diagram illustrating a change according to an operating state by checking.

In general, a fuel cell hydrogen supply system (device) for automobiles includes a fuel tank 10 in which hydrogen is stored, a regulator 20 that controls the pressure of hydrogen supplied from the fuel tank 10, and the pressure in the regulator 20. An ejector 30 that supplies the adjusted hydrogen to the stack (S), and the hydrogen supplied by being installed on the hydrogen supply line 12 that supplies hydrogen to the ejector 30 from the fuel tank 10 and the stack (S) ) Of the heat exchanger 40 for heat exchange of the cooling water discharged from the stack (S), the recirculation line 50 for supplying the gas discharged from the stack S to the ejector 30, and the cooling water supplied to the heat exchanger 40. It includes an adjustment unit 60 for adjusting the amount. See Registered Patent No. 1281011 (2013.06.26.).

The fuel tank 10 is a tank that stores hydrogen and is provided to withstand a pressure of several hundreds of bars or more, and at the same time, it is provided to have durability that is not destroyed by an external collision. The regulator 20 is a device that adjusts the pressure of hydrogen supplied from the fuel tank 10 and may be configured in two stages as needed. The ejector 30 is a device that supplies hydrogen whose pressure is controlled by the regulator 20 to the stack S, and is connected to a recirculation line 50 to the side of the ejector 30 to introduce hydrogen. The heat exchanger 40 is installed in the hydrogen supply line 12 between the fuel tank 10 and the ejector 30, and the cooling water discharged from the stack S and the hydrogen passing through the hydrogen supply line 12 are Heat exchange is performed. Here, since the cooling water discharged from the stack S has a higher temperature than the hydrogen passing through the hydrogen supply line 12, the hydrogen passing through the hydrogen supply line 12 is preheated by the waste heat of the cooling water and the stack ( S) is supplied. The recirculation line 50 is a line for circulating the exhaust gas discharged from the stack S to the ejector 30, and contains a greater amount of hydrogen than the hydrogen gas input to the stack S can react. Since it is supplied, the exhaust gas discharged from the stack S contains a considerable amount of excess hydrogen gas.

The control unit 60 is provided to adjust the amount of cooling water supplied to the heat exchanger 40, and as the amount of cooling water is adjusted, the temperature of the hydrogen gas supplied to the ejector 30 can be adjusted. The control unit 60 is installed on the hydrogen supply line 12 as shown in FIG. 3 and according to the pressure of the working fluid accommodated in the working fluid, the temperature sensitive tube 62 for accommodating the working fluid. It consists of a pressure reducing valve 64 that operates and a communication pipe 63 communicating between the temperature sensing cylinder and the pressure reducing valve. Here, it is preferable that the heat-sensitive tub 62 is provided to surround the outer periphery of the hydrogen supply line 12 in order to increase the heat transfer area.

The pressure reducing valve 64 has a valve seat 66b having a port 66a formed at the inner center of the cooling water supply line 42 for supplying cooling water to the heat exchanger 40 as shown in FIG. 4 in the axial direction. The extended partition (66), the housing (67) formed on the circumference of the cooling water input line (46) corresponding to the partition (66), and the interior of the housing (67) are divided up and down, A diaphragm 68 provided to communicate with 62, an opening/closing member 69 installed on the lower surface of the diaphragm 68 to open and close the port 66a by the operation of the diaphragm 68, and the opening/closing member 69 ) Consists of a spring 70 installed to support elasticity.

The partition wall 66 is installed so as to cross the inside of the cooling water supply line 42 and a valve seat 66b having a port 66a formed at the center thereof is provided to extend in the axial direction. The amount of cooling water supplied to the heat exchanger 40 is determined according to whether the port 66a formed in the valve seat 66b is opened or closed.

The housing 67 is installed on the circumference of the cooling water input line 46 corresponding to the partition wall 66, and an opening 67a communicating with the thermal sensor 62 is formed at the upper side. It is preferable that the housing 67 has an annular flat cross-section so that the diaphragm 68 can be installed.

The diaphragm 68 is installed inside the housing 67 and divides the inside of the housing 67 up and down. Here, the divided upper portion 67b of the housing 67 is formed to communicate with the thermal sensor 62, and the divided lower surface of the housing 67 opens and closes the port 66a of the valve seat 66b. The member 69 is installed. Therefore, the diaphragm 68 pushes the diaphragm 68 while the working fluid inside the thermosensitive tube 62 expands when the temperature of the working fluid accommodated in the thermosensitive tube 62 rises and evaporates. In addition, when the temperature of the working fluid accommodated in the thermosensitive tube 62 decreases and condenses, the diaphragm 68 contracts the working fluid inside the thermosensitive tube 62 to form a negative pressure, thereby restoring the diaphragm 68 to the state before expansion. Let it.

The opening/closing member 69 is provided to open and close the port 66a by the operation of the diaphragm 68, a stem 69a fixed to the diaphragm 68, and a port formed under the stem 69a. It consists of a contact member (69b) in close contact with the (66a).

The spring 70 is provided so that the opening and closing member 69 is elastically supported, and the contact member 69b is pressed by the spring 70 to seal the port 66a of the valve seat 66b. Therefore, when the working fluid accommodated in the temperature sensing vessel 62 is condensed and a negative pressure is formed above the tension of the spring 70, the diaphragm 68 operates and the coolant input line 46 is opened.

A method of controlling the temperature of hydrogen gas supplied to an ejector according to a fuel cell hydrogen supply system for automobiles will be described. In summer, since the temperature of the atmosphere is high, the temperature of hydrogen supplied to the fuel tank 10 also rises. Therefore, the working fluid accommodated in the thermal sensor 62 evaporates to increase the pressure, and the increased pressure moves to the upper portion of the housing 67 in communication with the thermal casing 62 and moves the diaphragm 68 downward. Pressurized. At this time, the opening/closing member 69 closes the port 66a formed in the valve seat 66b while maintaining a lowered state not only by the tension of the spring 70 but also by the pressing force of the diaphragm 68. Therefore, the hydrogen supplied from the fuel tank 10 flows to the ejector 30 as it is at the temperature discharged from the fuel tank 10 because the cooling water does not flow to the heat exchanger 40.

Next, when the temperature decreases, the temperature of hydrogen supplied to the fuel tank also decreases. When the temperature of the hydrogen supplied from the fuel tank 10 decreases, the working fluid contained in the temperature sensing vessel 62 is condensed to reduce the pressure, thereby forming a negative pressure in the temperature sensing vessel 62. When a negative pressure is formed in the temperature sensing tube 62, the diaphragm 68 overcomes the tension of the spring 70 as shown in FIG. 5 and is convexly bent upward. Accordingly, the opening/closing member 69 fixed at the center of the diaphragm 68 rises to open the port 66a formed in the valve seat. When the port 66a formed in the valve seat 66b is opened as described above, the cooling water flows into the heat exchanger 40 to exchange heat with hydrogen, so that the temperature of hydrogen supplied to the ejector 30 increases.

As described above, since the pressure reducing valve 64 operates to adjust the amount of cooling water in response to an increase or decrease in temperature, it is possible to adjust the relative humidity of hydrogen entering the stack S without a separate driving source. Accordingly, since the fuel cell hydrogen supply system for automobiles supplies hydrogen with an appropriate humidity, phenomena such as flooding or dry-out do not occur, the efficiency of the fuel cell can be further improved.

6 will be described in detail with respect to the pressure reducing valve 64 of the present invention with reference to the accompanying drawings. The pressure reducing valve 64 of the present invention minimizes its volume and simplifies the configuration to avoid complications to increase durability, and to prevent jamming on the communication pipe 63 during inspection or repair, the actuator in FIGS. 2 to 5 The housing 67 exposed to the outside to act as an actuator and the diaphragm 68 complicatedly configured inside the housing 67 and an additional configuration used to operate the housing 67 are not used. Instead, a baloon 80 capable of changing the volume, such as an air bag or a balloon, is used as an actuator as shown in FIG. 7.

In FIG. 6, the communication pipe 63 is fixed in direct contact with the cooling water input line 46. To this end, a communication pipe fitting bracket 46a perforated (a hole formed) is formed vertically (b2) so as to fit and fix the body circumference of the communication pipe 63 above the lengthwise direction of the cooling water input line 46, and , Here, through welding or bonding, the outer circumferential body of the communication pipe 63 is tightly sealed and coupled to prevent water leakage.

As shown in Fig. 6B, the end side of the communication pipe 63 conforms to the flow direction (along the flow direction) so as to minimize the flow obstruction of the cooling water a3, and is aligned side by side along the length of the cooling water input line 46. It is bent (b3) at a right angle so that it is (b1) and changes the direction from vertical (b2) to horizontal (b1). Thereafter, as shown in Fig. 6A, the opened inlet of the balun 80, that is, the balun inlet 80a, is closely and firmly attached to the bent (b3) communication pipe end 63a so as to completely prevent leakage. In this way, the balun 80 coupled to the end of the communication pipe 63 naturally conforms to the flow direction of the cooling water a3 and is aligned parallel to the longitudinal direction of the cooling water input line 46 to minimize resistance ( b1) becomes.

If, as the pressure (volume) of the working fluid a1 accommodated in the thermal bath 62 increases, the working fluid (a1) directly fills the balun 80, and accordingly, the volume of the balun 80 increases (expands). ), due to the cooling water a3 in the cooling water input line 46, a change in volume (pressure) may occur again, so that the operation of the thermostat 62 may not be properly reflected. Therefore, it is necessary to block heat thoroughly so that the change in volume is minimized again.To this end, the member of the balun 80 is provided as a high-performance heat insulating member, or by providing a very thick skin of the balun 80 to conduct heat conduction. It is desirable to minimize it.

However, since the balun 80 continues to contact the cooling water a3 even though an insulating member and a thick material are used, the working fluid a1 is affected by the temperature of the cooling water a3. Another advanced method is needed that can be completely unaffected by the cooling water (a3) in (46). In this, the fluid in which the volume change (volume change) is minimal due to heat change can be used only as a fluid filling the balun 80, which is referred to as the balun filling fluid (a2), and the balun filling It is preferable to select a fluid having a specific gravity (density, weight) different from that of the working fluid a1 as the fluid a2. In the example of the drawings, the balun filling fluid (a2) is selected as a fluid having a large specific gravity so that it does not mix with the working fluid (a1). As shown in FIG. 6A, an interface a12 due to a difference in specific gravity occurs between the working fluid a1 and the balun filling fluid a2 in the communication pipe 63.

The operation method will be described with reference to FIGS. 7 and 8. First, when the pressure (volume) of the working fluid a1 accommodated in the thermal bath 62 increases, the working fluid a1 pushes the balun filling fluid a2, so in FIG. 8, the interface a12 is the first It moves downward (c2) from the high point (d1) to the low point (d2). Therefore, the volume change of the difference in the communication pipe 63, that is, the volume change d12 in the tube, the balun filling fluid a2 flows into the balun 80 and when the balun is filled, the volume of the balun 80 becomes It expands like a ball, and eventually, a section of the coolant input line 46 is closed to block the flow of the coolant a3.

Conversely, when the pressure of the working fluid (a1) decreases, the working fluid (a1) attracts the balun filling fluid (a2), so that the boundary surface (a12) moves upward (c1) from the low point to the high point. Since the balun filling fluid (a2) escapes from the balun 80 by the change d12, the volume of the balun 80 decreases to its original value, allowing the flow of the cooling water a3 again. At this time, if the balun 80 is made of an elastic material such as rubber that has an elastic recovery force against a change in volume, the pressure of the working fluid a1 can be operated while maintaining an appropriate tension due to the elastic recovery force. It serves as the spring 70 of the opening and closing member 69 illustrated in 2 to 5.

Eventually, the volume change of the balun 80, that is, the change in the volume of the balun (e12) coincides with the change in the volume in the tube (d12), and, in place of the working fluid (a1), only the balun filling fluid (a2) is Since the balun 80 disposed inside the cooling water input line 46 is filled, the working fluid a1 is not affected by the temperature of the cooling water a3 at all, It will work.

In addition, although not shown in the drawing, the communication pipe 63 allows all or only a portion of the boundary surface to move as a transparent member such as glass or transparent plastic to prevent the movement (movement) of the boundary surface a12 from the outside. It can be configured to be able to confirm. Through this, the manager (inspector, driver) may check and confirm the normal operation of the pressure reducing valve 64 and take appropriate measures.

In this case, a pigment may be added in a different color between the working fluid a1 and the balun filling fluid a2 to facilitate the identification of the boundary surface a12. Alternatively, a float having an intermediate specific gravity of the working fluid a1 and the balun filling fluid a2 is inserted and interposed between the interface a12 to facilitate identification and identification. . The float serves to block both the working fluid (a1) and the balun filling fluid (a2) so that they do not come into contact with each other, thereby completely separating the two fluids so that they do not mix with each other between the interface (a12). It can be.

DESCRIPTION OF SYMBOLS 10 Fuel tank 20 Regulator 30 Ejector 40 Heat exchanger 50 Recirculation line 60 Control part 62 Pressure reducing cylinder 64 Pressure reducing valve 80 Balun

Claims (1)

In the stack, a regulator regulates the pressure of high-pressure hydrogen in a fuel tank, an ejector supplies the pressure-controlled hydrogen to the stack, and is installed between the fuel tank and the ejector to supply hydrogen. A heat exchanger heat exchanges the discharged cooling water, and excess hydrogen of the exhaust gas discharged from the stack is circulated to the ejector through a recirculation line,
The control unit is provided on the hydrogen supply line so as to surround the outer circumference of the hydrogen supply line, and includes a pressure reducing valve that operates as an actuator according to the pressure of the working fluid accommodated in the working fluid, and a pressure reducing valve that is supplied to the heat exchanger. Adjust the amount of coolant to be used,
The communication pipe is communicated between the temperature sensing cylinder and the pressure reducing valve, and is fixed in contact with the cooling water input line, and a communication pipe perforated to fit and fix the body circumference of the communication pipe is fitted above the cooling water input line in the longitudinal direction. The bracket (46a) is composed of a vertical (b2), and the outer circumferential body of the communication pipe is fitted here,
The end of the communication pipe is bent (b3) at a right angle so as to be aligned (b1) side by side along the length of the cooling water input line, and the direction is changed from vertical (b2) to horizontal (b1), and becomes the bent (b3). The open balun inlet 80a of the balun is tightly attached to the provided communication pipe end 63a,
The balun coupled to the end of the communication pipe is aligned (b1) parallel to the longitudinal direction of the cooling water input line to reduce resistance by conforming to the flow direction of the cooling water (a3),
When the pressure and volume of the working fluid (a1) accommodated in the thermal bath increases, the volume of the working fluid (a1) is configured to expand as it directly fills the balun,
A balun filling fluid (a2) having a greater specific gravity than the working fluid (a1) is provided, so that an interface (a12) due to a specific gravity difference between the working fluid (a1) and the balun filling fluid (a2) is provided in the communication pipe. A hydrogen supply device of a fuel cell vehicle, which is formed so as not to be mixed with each other, so that only the balun filling fluid (a2) is used to fill the balun.

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