KR100837913B1 - System for warming fuel cell stack to improve cold-start performance - Google Patents

Abstract

A system for warming a fuel cell stack is provided to allow the warm air discharge from a stack to be circulated in enclosure in case of cooling starting, to increase the operation temperature of a stack by cooling water and to allow the stack to be operated under optimized condition within a short time. A system for warming a fuel cell stack comprises a stack(100) which has a manifold(M) where hydrogen, air, cooling water and reaction product water flow, an air inlet and an air outlet formed at the both sides, and a temperature sensor(200A) installed inside; an enclosure warming region(300) which surrounds the entire outside of the stack and has a recirculation path so as to circulate the air discharged from the stack in case of the cooling starting inside the installed enclosure; and a controller(700) which is inputted with the temperature sensed from the temperature sensor in case of the cooling starting to recirculate the air discharged from the stack to the enclosure warming region, thereby increasing the temperature of the stack.

Description

System for warming fuel cell stack to improve cold-start performance}

1 is a view showing a fuel cell stack insulation system configuration for improving cold startability according to the present invention.

Figure 2 is a view showing the enclosure thermal insulation area is installed enclosure according to the present invention.

3 is a view showing the state of frozen water generated in the stack during a typical cold start.

Figure 4 is a flow chart showing the operating state of the fuel cell stack insulation system for improving cold startability according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: fuel cell stack 110: air intake

130: air outlet 200A: temperature sensor

300: enclosure thermal insulation area 310: enclosure

315: recirculation passages 330, 350: first and second valves

500: cooling water heating line 510: bypass valve

530: heater 610: water pump

700: controller

The present invention relates to a fuel cell stack insulation system for improving cold startability, and more particularly, to circulate warm air discharged from the stack in an enclosure during cold start, and to heat the coolant to help increase the operating temperature of the stack. The present invention relates to a fuel cell stack insulation system for improving cold startability, which enables the stack to operate optimally in time.

In general, a fuel cell used for driving an automobile produces a desired power by stacking cells that generate electrons as ions move between a cathode and an anode around an electrolyte membrane. The stack of several cells is called a stack, and in order to keep the structure under the optimal stacking pressure of each cell, a plurality of cells are stacked and a fastening plate is coupled to the outside thereof.

Automotive fuel cells must be able to start up and operate in any climatic condition, but running fuel cells at temperatures below zero or near zero will create problems in producing electricity from the stack.

In the conventional fuel cell system, the freezing prevention can prevent freezing of the cooling water used in the fuel cell system by using ethylene glycol developed for the stack as cooling water instead of distilled water. That is, the cooling water can be prevented from freezing when stored at subzero temperatures.

However, when the fuel cell stack is operated at a subzero temperature or when the cold ethylene glycol coolant flows below the stack cooling circuit, the generated water on the cathode side immediately freezes. The frozen area becomes an area that interferes with the reaction of oxygen and hydrogen, preventing the stack from producing electricity. If such a phenomenon is maintained, when the fuel cell vehicle is left for a long time under freezing, even if ethylene glycol is used to prevent freezing of the cooling water, the generated water in the stack may freeze, making the vehicle impossible to operate.

Therefore, in the related art, the following techniques have been applied to improve the cold startability and increase the temperature of the stack in a low temperature state.

After the stack operation is finished, the stack cooling water is drained from the stack, and the freezing water is delayed by freezing the cooling water in the stack below the freezing temperature. During the stack operation, the drained water is stacked using a water pump or the like. The coolant is then used to cool the stack. This requires an additional device for draining the water, and since the drained water also freezes, this frozen water dissolving device is also needed, which leads to a long startup time.

 In addition, the stack may be heated using a burner or the like, and the burner uses hydrogen, which lowers the hydrogen utilization rate (vehicle fuel economy), requires additional equipment such as a burner, and uses a fire. There is this.

The present invention has been made to solve the above problems, an object of the present invention is to form an enclosed insulating region to keep warm by increasing the temperature of the stack by recirculating the air discharged from the stack, the cooling water to prevent the generated water in the stack freezing By providing a cooling water heating line for heating to provide a fuel cell stack insulation system for improving the cold startability to be easily cold start even at sub-zero temperatures.

In order to achieve the above object, the present invention is a manifold flowing hydrogen and air, cooling water and reaction generation water is formed, the air inlet and the air outlet is formed on both sides, the fuel cell stack is installed inside; An enclosure insulation region in which a recirculation passage is installed so as to circulate air discharged from the fuel cell stack during cold start in an enclosure installed to cover the entire exterior of the fuel cell stack; And a controller configured to control the air discharged from the fuel cell stack to increase the temperature of the fuel cell stack by recirculating the enclosure insulation region by receiving a temperature value sensed by the temperature sensor during cold startup. It provides a fuel cell stack insulation system for improving the cold start.

The enclosure may include an inner case spaced apart from the fuel cell stack, and an outer case in which the recirculation passage is formed to circulate air discharged from the fuel cell stack in a region spaced apart from the inner case.

The fuel cell stack is connected to a circulation path including a water pump and a radiator so as to circulate the cooling water discharged during normal operation, and the water so that the cooling water can be bypassed and heated by the radiator during cold start-up. A coolant heating line including a bypass valve and a heater is further connected between the pump and the radiator.

A first valve for blocking the air outlet installed to be connected to the fuel cell stack during cold start and opening the recirculation passage to introduce air discharged from the fuel cell stack into the recirculation passage; A second valve for discharging the air circulated in the recirculation passage to the outside when the temperature of the stack rises is further installed.

The inner case is characterized in that the material has a higher thermal conductivity than the outer case.

Hereinafter, a fuel cell stack insulation system for improving cold startability according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Attached, Figure 1 is a view showing the configuration of the fuel cell stack insulation system for improving the cold startability according to the present invention, Figure 2 is a view showing the enclosure insulation region is installed enclosure according to the present invention, Figure 3 is a general cold start It is a figure which shows the frozen water produced state in a stack.

As shown in FIG. 1 and FIG. 2, the fuel cell stack insulation system for improving cold startability according to the present invention uses air discharged from the fuel cell stack 100 and cooling water supplied to the fuel cell stack 100. During cold start, the stack temperature is increased to have maximum performance in a short time. The enclosure includes a fuel cell stack 100, an enclosure 310, a recirculation passage, a first valve 330, and a second valve 350. The heat insulating area 300, the bypass valve 510, the cooling water heating line 500 provided with the heater 530, and a controller 700 controlling the same are configured.

The fuel cell, not shown in the drawing, is an apparatus for generating electrical energy by reacting hydrogen and oxygen, and an anode in which hydrogen is supplied to both sides with an electrolyte membrane through which hydrogen ions (H ⁺ ) are transferred. And a current collector plate and a fastening plate in a plurality of unit cells in which a membrane-electrode assembly (MEA) having a cathode and a cathode supplied with air and a separator plate are sequentially stacked. (End plates) are combined to form a fuel cell stack, and a plurality of square hole-shaped inlet and outlet manifolds into which hydrogen, air, and coolant flow in and out are formed at both ends of each longitudinal direction. In addition, the fuel cell stack flows hydrogen, air, cooling water, and reaction water for electrochemical reaction through each manifold.

As illustrated in FIGS. 1 and 2, the fuel cell stack 100 having the manifold M through which hydrogen, air, cooling water, and reaction product flows is formed has a temperature sensor 200A installed therein and an enclosure outside. 310 is installed surrounding the entire exterior of the fuel cell stack 100.

The enclosure 310 is composed of an inner case 311 and an outer case 313, the inner case 311 is installed spaced apart from the fuel cell stack 100, the outer case 313 is the inner The case 311 is spaced apart from each other, and the inner case 311 is more preferably formed of a material having a higher thermal conductivity than the outer case 313.

Warm air discharged from the fuel cell stack 100 may circulate in an area between the inner case 311 and the outer case 313 of the enclosure 310 installed outside the fuel cell stack 100. Recirculation passage 315 is formed.

An air inlet 110 is formed at one side of the fuel cell stack (hereinafter, referred to as a stack 100), and an air outlet 130 is formed at the other side thereof, and is preferably installed in communication with the recirculation passage 315. Do.

The air outlet 130 is provided with a first valve 330, the first valve 330 is composed of a solenoid valve stack 100 by a temperature sensor 200A installed inside the stack 100 When it is detected that the temperature is less than the appropriate temperature, that is, when the cold start, the air outlet 130 and at the same time open the recirculation passage 315 to open the recirculation passage 315 warm air discharged from the stack 100 To cycle).

The warm air discharged from the stack 100 circulates the recirculation passage 315 without going out to help the temperature rise of the stack 100 to exhaust air that is relatively warmer than the ambient temperature, and at the same time the enclosure 310 is stacked The heat generated from the 100 does not go out of the stack so that the temperature of the stack 100, which is cooled by cold storage, may be quickly increased.

In addition, a second valve 350 is installed below the outer case 313 of the enclosure 310, and the second valve 350 is configured as a solenoid valve to circulate the recirculation passage 315 and the stack. It is installed to open and close to discharge the air that helped the temperature rise of 100 to the outside.

Therefore, the warm air reacted and discharged from the stack 100 during cold startup is circulated along the recirculation passage 315 by the opening of the first valve 330 to help increase the temperature of the stack 100. After a while, when the temperature of the stack 100 is raised, the warm air is discharged to the outside by opening the second valve 350.

On the other hand, in the stack 100, a cooling water heating line 500 which raises the temperature of the fuel cell cooling water so that the generated water after the reaction does not freeze, and thus is easily cold-started even at the subzero temperature detected by the temperature sensor 200A. Is installed.

As shown in FIG. 3, when sub-zero cooling water flows into the cooling water passage C of the separator S of the stack 100 under sub-zero conditions, oxygen is supplied to the cathode and the anode in the air supplied to the cathode. When hydrogen is reacted in the electrode film, electricity is generated and generated water is generated at the cathode side. The generated water is frozen in the stack 100 by the cold temperature of the separator S.

In the stack 100 in which the generated water is frozen, an electrode film E which does not participate in a chemical reaction due to the generated water freezing I is generated, thereby generating electricity required for operation even when oxygen and hydrogen are supplied to the stack 100. Since it is difficult to perform normal operation of the fuel cell system, it is necessary to install a cooling water heating line 500 that increases the temperature of the stack 100 by heating the cooling water to facilitate cold starting.

As shown in FIG. 1, the cooling water heating line 500 includes a bypass valve 510 and a heater 530, and is provided by a water pump 610 connected to the stack 100. It is more preferably installed on the circulation path through which the supplied coolant flows and connected between the water pump 610 and the radiator 630 to have a shorter bypass path than in normal operation.

That is, a bypass valve 510 is installed between the water pump 610 and the radiator 630, and a heater 530 is connected and installed to heat the cooling water passing through the bypass valve 510 during cold start. do.

The bypass valve 510 bypasses the radiator 630 without passing through the radiator 630 during cold start and flows into the heater 530. In the normal operation, the coolant is radiator 630. ) To pass through.

The heater 530 is operated by using electricity generated in the stack 100 to raise the temperature of the coolant, and the coolant whose temperature is increased is introduced into the stack 100 to freeze the generated water in the stack 100. Do not let it.

On the other hand, when the coolant circulates normally through the bypass valve 510 to the radiator 630 when operating under the temperature condition of the image, that is, about 20 degrees or less, the temperature of the stack 100 itself and the temperature of the coolant. Etc., the optimum temperature condition of the stack 100 may not be maintained.

In fact, when the vehicle is driven at 20-60kph driving conditions at about 3 degrees, the temperature of the stack 100 is operated at less than 65 degrees, so that it is difficult to achieve the maximum performance. As a result, a floating phenomenon occurs and a phenomenon in which the cell voltage is locally lowered in the stack 100 occurs. Therefore, in this case, by warming and heating the stack 100 with warm air discharged from the stack 100 through the present invention, it is possible to prevent a floating phenomenon in the stack 100, thereby providing a stable stack 100 output. Can be obtained, and optimum performance can be maintained.

In addition, the present invention is connected to the outside air temperature sensor 200B that can detect the outside temperature, the outside air temperature detected by the outside air temperature sensor 200B when driving the vehicle is an image, but a relatively low range (20 degrees or less image) Condition), it helps to increase the operating temperature of the stack 100 to create a condition (temperature conditions of the image 65 ~ 75 degrees) that the stack 100 can operate optimally in a short time, the optimum temperature Helping to maintain maintenance can improve vehicle performance.

The controller 700 for controlling the components to be operated is connected to the enclosure thermal insulation area 300 and the cooling water heating line 500 to install the temperature sensor 200A and the outside air temperature sensor 200B inside the stack 100. The temperature value sensed by the sensor is received and calculated, and the first valve 330 and the second valve 350 of the enclosure thermal insulation area 300 are controlled according to the calculated result, and the coolant heating line ( The bypass valve 510 and the heater 530 of the 500 are controlled.

The controller 700 receives the temperature values of the inside and outside of the stack 100, and when the temperature is below zero, the controller 700 controls the solenoid valve that is the first valve 330 of the enclosure thermal insulation area 300 to control the solenoid valve in the stack 100. The discharged warm air causes the recycle passage 315 to circulate.

In addition, the controller 700 receives the temperature values of the stack 100 and the outside air, and controls the bypass valve 510 of the coolant heating line 500 when the temperature is below zero, thereby cooling the heater 530. By controlling to pass, the heater 530 controls the cooling water flow rate to increase the temperature of the stack 100 quickly in a short time while controlling the heater 530 to heat the cooling water using electricity generated in the stack 100.

Looking at the operating state of the fuel cell stack insulation system for improving cold startability according to an embodiment of the present invention configured as described above are as follows.

4 is a flowchart illustrating an operating state of the fuel cell stack insulation system for improving cold startability according to the present invention.

As shown in FIG. 4, when the fuel cell system is operated, the stack and outside temperature are controlled by the temperature sensor 200A installed inside the stack 100 and the outside air temperature sensor 200B installed outside to sense the outside temperature. Will be detected.

The controller 700 which has received the temperature value sensed by the temperature sensor 200A and the outside temperature sensor 200B calculates the temperature to increase the temperature of the stack 100 so that the temperature is below zero. In order to control the enclosure thermal insulation region 300 and the coolant heating line 500 installed outside the stack 100.

When the controller 700 is below freezing temperature, the controller 700 controls the first valve 330 of the enclosure thermal insulation area 300 to allow the warm air discharged from the stack 100 to enter the recirculation passage 315. ), That is, while the air outlet 130 is blocked, the recirculation passage 315 is opened at the same time so that the warm air is recirculated along the recirculation passage 315 without being discharged to the outside.

The warm air recirculating in the recirculation passage 315 between the inner case 311 and the outer case 313 of the enclosure 310 causes the temperature of the stack 100 to rise and the temperature of the stack 100 to rise to fuel When the battery system again exhibits optimum performance, the controller 700 controls the second valve 350 and opens the second valve 350 to discharge the warm air circulated in the recirculation passage 315. Do it.

In addition, during cold start, the controller 700 controls the bypass valve 510 of the cooling water heating line 500 to heat the cooling water supplied from the water pump 610 according to the input subzero temperature. The cooling water does not flow into the radiator 630 introduced during normal operation, but bypasses the flow of the cooling water into the heater 530.

The controller 700 operates the heater 530 using the electricity generated in the stack 100, and controls the flow rate to heat the cooling water introduced into the heater 530 more quickly, and the heated cooling water is stacked. It is introduced into the (100) to increase the temperature of the stack 100 so as not to freeze the generated water in the stack (100).

Then, when the temperature of the elevated stack 100 is sensed and the optimum image temperature is reached, the fuel cell system operates normally.

According to the present invention, the air discharged from the stack 100 during cold start is not immediately discharged to the outside, and the temperature of the stack 100 is increased by the enclosure insulation region 300, and at the same time, the fuel cell cooling water is also cooled water heating line 500. Thereby, the cooling water is heated to prevent freezing of the generated water in the stack 100, thereby effectively improving cold start even at subzero temperatures.

On the other hand, the present invention is not limited to the above-described embodiment, and those skilled in the art to which the present invention pertains without departing from the gist of the invention claimed in the claims can be variously modified. Of course, such changes are intended to be within the scope of the claims set forth.

As described above, the fuel cell stack insulation system for improving cold startability according to an embodiment of the present invention heats the coolant during cold start at subzero temperature to insulate the stack with stack exhaust air 5 to 20 degrees higher than the outside temperature. The heating prevents freezing of the stack produced water on the cathode side which may occur during cold start, and prevents the formation of the generated water on the stack cathode side in the liquid state at a relatively low ambient temperature, thereby improving the durability of the stack.

In addition, by using the air discharged from the stack circulated in the recirculation passage of the enclosure installed outside the stack, the temperature of the stack is raised and maintained without additional electricity consumption, thereby improving the efficiency of the fuel display system.

In addition, by installing a bypass valve and a heater in the line supplied to the cooling water, the amount of temperature to be raised may be minimized, thereby minimizing the amount of additional electricity consumed for cold start.

Claims (5)

A manifold (M) through which hydrogen, air, coolant, and reaction product flows is formed, and an air inlet 110 and an air outlet 130 are formed at both sides, and a fuel cell stack 100 in which a temperature sensor 200A is installed. ); Enclosure insulation region 300 is provided with a recirculation passage 315 to circulate the air discharged from the fuel cell stack 100 during cold start inside the enclosure 310 installed to cover the entire outside of the fuel cell stack 100 ; And During cold startup, the air discharged from the fuel cell stack 100 receives the temperature value detected by the temperature sensor 200A to recycle the enclosure thermal insulation region 300 to increase the temperature of the fuel cell stack 100. Fuel cell stack insulation system for improving cold startability, characterized in that it comprises a controller; The method of claim 1, The enclosure 310 may have an inner case 311 installed spaced apart from the fuel cell stack 100, and air discharged from the fuel cell stack 100 may circulate in an area spaced apart from the inner case 311. Fuel cell stack insulation system for improving the cold startability, characterized in that consisting of an outer case (313) formed with the recirculation passage (315). The method of claim 1, The fuel cell stack 100 is provided with a circulation path including a water pump 610 and a radiator 630 so as to circulate the cooling water discharged during normal operation, and the cooling water to the radiator 630 during cold startup. Cooling water heating line 500 including the bypass valve 510 and the heater 530 is further installed between the water pump 610 and the radiator 630 so as to bypass and heat the inlet. Fuel cell stack insulation system for improving cold startability. The method according to claim 1 or 2, Air discharged from the fuel cell stack 100 by blocking the air outlet 130 connected to the fuel cell stack 100 and opening the recirculation passage 315 in the enclosure heat insulating region 300 and at the same time. First valve 330 for introducing the gas into the recirculation passage 315 and a second valve 350 for discharging the air circulated in the recirculation passage 315 to the outside when the temperature of the fuel cell stack 100 rises. Fuel cell stack insulation system for improving the cold startability, characterized in that the further installed. The method of claim 2, The inner case 311 is a fuel cell stack insulation system for improving cold startability, characterized in that the material having a higher thermal conductivity than the outer case (313).

Images