JPH0945353A - Portable fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable fuel cell by which the temperature distribution in a battery stack at fuel cell starting time can be efficiently uniformized. SOLUTION: A plane-shaped starting heater 33 is arranged in a contact shape over the whole on outside surfaces of both end plates 33 of a fuel cell main body 3. The starting heater 33 is actuated by electric power generated by the fuel cell main body 3, and raises a temperature in the vicinity of an outside surface in the fuel cell main body 3, and uniformizes the temperature distribution in the fuel cell main body 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable fuel cell, and more particularly to improvement of a technique for raising the temperature of a cell stack at the time of starting the fuel cell.

[0002]

2. Description of the Related Art In a portable fuel cell, reaction air and hydrogen gas are supplied into a cell stack and an electrochemical reaction at that time is used to generate electricity. Therefore, at the time of startup when the temperature of the cell stack is low, the reaction efficiency of air and hydrogen gas is low, so that the power generation efficiency of the portable fuel cell is not good.

The temperature of the battery stack gradually rises due to the heat of reaction as the reaction proceeds, but the rate of temperature rise is slow. Therefore, it is necessary to raise the temperature of the battery stack at room temperature to the operating temperature (about 100 ° C.) in a short time at startup. As a means for this, conventionally, a reaction air heating heater is provided on the reaction air inlet side of the fuel cell body. As a result, the reaction air that has exchanged heat with the reaction air heating heater is supplied into the fuel cell body, and the temperature of the cell stack is raised by the heat exchange between the reaction air and the cell stack.

[0004]

By the way, since the battery stack is constructed by alternately stacking a plurality of cells and separators, the cells located on the outermost side have cells only on one side. . Therefore, in the outermost cell, a large amount of heat is radiated to the outside from one surface where no adjacent cell is present, and the temperature is less likely to be raised than the cells located near the central portion. As a result, there is a problem that the temperature distribution in the battery stack is difficult to be uniform.

In addition, in the low temperature portion of the battery stack, the water produced by the above reaction is difficult to be discharged, resulting in a shortened battery life and a decrease in power generation efficiency. Here, in order to solve the above problems,
It suffices that the heat radiation to the outside of the battery stack is suppressed and the temperature of the outermost cell is easily raised. As a means for that, it is possible to dispose a heat insulating material on the outer surface of the fuel cell body. However, since the heat exchange between the reaction air heater and the reaction air and the heat exchange between the reaction air and the battery stack are not sufficiently performed, even in this case, the temperature distribution in the battery stack is effectively made uniform. It cannot be said that

Therefore, in view of the above problems, it is an object of the present invention to provide a portable fuel cell capable of efficiently equalizing the temperature distribution in the cell stack at the time of startup.

[0007]

In order to solve the above problems, in the invention according to claim 1, a fuel cell main body for generating electric power by using hydrogen from a hydrogen supply source and air taken from the outside in a portable case. And a starting heater that heats the fuel cell main body using electric power generated by the fuel cell main body at the time of start-up, wherein the starting heater is provided on the outer surface of the fuel cell main body. It is characterized in that it is arranged in contact with the fuel cell main body.

According to a second aspect of the invention, the starting heater is a planar heater. In the invention according to claim 3, in the fuel cell main body, a cell in which an anode and a cathode are arranged in an electrolyte and a separator in which a hydrogen gas passage and an air passage are formed are alternately laminated, and both ends thereof are paired. In the laminated structure held by the end plate, the starting heater is embedded in a recess formed in the inner surface of the end plate.

According to a fourth aspect of the invention, the starting heater is a rod-shaped heater and is embedded in a cylindrical space formed inside the end plate. The invention according to claim 5 is characterized in that the start-up heater is arranged with a higher density on the air inlet side than on the air outlet side of the fuel cell main body.

According to the portable fuel cell of the first to fifth aspects, the start-up heater heats the fuel cell main body by using the electric power generated by the fuel cell main body to generate heat at the time of start-up. The temperature of the fuel cell main body tends to be lower in the portion closer to the outer surface than in the central portion, but since the start-up heater is arranged along the outer surface of the fuel cell main body, The temperature distribution with the surface can be made uniform.
Further, since the start-up heater is arranged in contact with the fuel cell main body, it is possible to directly and efficiently heat the fuel cell main body by heat conduction.

Here, since it is possible to easily arrange the start-up heater at a high density on a portion of the outer surface where the temperature tends to be low, it is possible to more effectively make the temperature distribution uniform. According to the portable fuel cell of claim 2, since the starting heater is a planar heater, it is easy to dispose the heater along the outer surface of the fuel cell main body.
The outer surface of the fuel cell body can be efficiently heated as a whole.

According to the portable fuel cell of the third aspect, since the fuel cell main body has a laminated structure, the temperature of the cells on the end plate side tends to be lower than the temperature of the cells in the central portion, but the starting heater has the fuel cell. Since it is embedded in the recess formed on the inner surface of the end plate of the main body, the temperature distribution between the central portion and the end plate side can be made uniform, and the heat generated by the start-up heater can be transferred to the outside. It is possible to heat the fuel cell body efficiently with less loss.

According to the portable fuel cell of the fourth aspect, since the starting heater is a rod-shaped heater, it is relatively inexpensive and economical. Further, since the start-up heater is embedded inside the end plate of the fuel cell body, heat loss generated in the heater is small and heat is efficiently conducted to the fuel cell body. According to the portable fuel cell of claim 5, the temperature of the air inlet side of the fuel cell main body tends to be lower than that of the air outlet side thereof, but the starting heater is located closer to the air inlet side than the air outlet side of the fuel cell main body. Since the fuel cells are arranged at a high density, the temperature distribution of the fuel cell body in the air flow direction can be made uniform.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 is an overall perspective view of a portable fuel cell, and FIG. 2 is a sectional view taken along line XX in FIG.

As shown in FIGS. 1 and 2, the portable fuel cell comprises a casing 1, a hydrogen storage alloy tank 2 and a fuel cell body 3. The housing 1 is divided into four spaces A, B, C and D by partition walls 10a, 10b and 10c, as shown in FIG. Housing 1
The space A on the left side of the inside is a hydrogen storage alloy tank storage chamber, and the hydrogen storage alloy tank 2 is stored therein.
Further, the central space B is a fuel cell main body mounting chamber, and the fuel cell main body 3 is mounted therein. On the other hand, the right side space C in the housing 1 is an air supply chamber, and the upper space D
Is a power generation control room. Although a slit-shaped air inlet 11 and an air outlet 12 are provided in the upper part of the housing 1, the housing 1 can be sealed by covering the upper lid 13 when the portable fuel cell is not used. It is possible.

As shown in FIG. 1, the hydrogen storage alloy tank accommodating chamber A has an opening 14 formed at the upper end thereof.
An openable / closable closing lid 15 is attached to the. The hydrogen storage alloy tank 2 has a structure in which a plurality of cylindrical hydrogen storage alloy tanks 20a (5 in the illustrated example) are arranged in a row between a pair of columns 21 in the horizontal direction, and the openings 14
It can be installed in the hydrogen storage alloy tank storage chamber A through.

A coupler 22 serving as a hydrogen gas outlet is provided at the upper end of one of the columns 21, and the coupler 22 and the hydrogen supply side manifold 23 are connected by a hydrogen supply pipe 41. There is. FIG. 3 is a view showing the fuel cell body 3. The fuel cell main body 3 includes a cell 31 having an anode on one side of the electrolyte layer and a cathode on the other side, and a separator 32 forming an air passage in the horizontal direction and a hydrogen gas passage in the vertical direction. A plurality of sheets are alternately laminated, and both side ends thereof are sandwiched by a pair of end plates 33. A hydrogen supply side manifold 23 and a hydrogen discharge side manifold 24 are provided on the upper surface and the lower surface.

The mounting direction of the fuel cell main body 3 inside the housing 1 is, as shown by arrows P1 and P2 in FIG. 2, that the reaction air flows from the right side to the left side and the exhaust air exchanges heat with the hydrogen storage alloy tank 2. It is set in the direction to be. As shown in FIG. 3, a pair of start-up heaters 34 are provided on the outer surfaces of the end plates 33 that form the fuel cell body 3. Hereinafter, the starting heater 34 will be described.

The starting heater 34 is, for example, a thin flat 250 W-silicon rubber heater, and is arranged in contact with the entire outer surface of both end plates 33 of the fuel cell main body 3. The starting heater 34 is operated by the electric power generated by the fuel cell main body 3 to heat the fuel cell main body 3 when the portable fuel cell is started, and is stopped during the normal operation.

The starting heater 34 is electrically connected to a controller 35 provided in the power generation control room D, and its operation and stop are controlled by the controller 35. That is, if the minimum value of the power generation voltage of the portable fuel cell is a certain reference value or more, the controller 35 enables the output to the outside and stops the starting heater 34. It should be noted that, even during normal operation, when the temperature of the fuel cell main body 3 decreases due to a decrease in reaction air temperature or the like, for example, the starting heater 34 is activated again.

With the above structure, the starting heater 34 is activated when the portable fuel cell is started, and the fuel cell main body 3 is operated.
Is heated. Here, since the start-up heater 34 is arranged in contact with the outer surfaces of the both end plates 33, the temperature rise in the vicinity of the outer surface of the fuel cell body 3 is facilitated and the temperature inside the fuel cell body 3 is increased. The distribution is made uniform. Next, the effect of the starting heater 34 in this embodiment will be described in comparison with the conventional example.

The conventional portable fuel cell has the same overall structure as that of the present embodiment shown in FIG. 2, except for the structure of the starting heater. That is, in the conventional example, as the starting heater 34, for example, a 400 W-SND finned sheathed heater is used, and the fuel cell main body 3 is used.
It is installed in the air supply chamber C without contacting with. Therefore, the fuel cell main body 3 is indirectly heated via the high-temperature reaction air that has exchanged heat with the startup heater.

On the other hand, the starting heater 34 of this embodiment is arranged in contact with the outer surfaces of both end plates 33 of the fuel cell body 3, as shown in FIG. Since it is directly heated by the heater 34 for heating, the temperature rise in the vicinity of the outer surface of the fuel cell body 3 is performed in a short time as compared with the conventional example, and in addition, the heat from the outermost cells in the fuel cell body 3 is increased. You can prevent loss. Therefore, the temperature distribution in the fuel cell body 3 can be effectively equalized, and the start-up time of the portable fuel cell can be shortened.

The effect of the starting heater 34 in this embodiment is also confirmed by the following experimental results. In the experiment, the portable fuel cells of this example and the conventional example were used, and the cell temperature of each fuel cell main body 3 was measured 10 minutes after startup. 8A to 8M are fuel cell main bodies 3 used in the experiment.
The temperature measurement position inside is shown. The fuel cell body 3
The number of stacked cells in the inside is 30, but for convenience of illustration,
Some are omitted. Further, as shown in FIG. 8, the temperature measurement positions are the air inlet portions E, for the first layer cell (outermost cell), the 16th layer cell (center cell) and the thirtieth layer cell (outermost cell). There are a total of 9 locations including H, K, central portions F, I, L and air outlet portions G, J, M.

FIG. 9 shows temperatures at three points of the air inlet portion K, the central portion L and the air outlet portion M of the 30th layer cell (outermost cell) in the above experiment. As shown in FIG.
In this embodiment, the fuel cell main body 3 is heated more efficiently than in the conventional example, and the temperature of the thirtieth layer cell (outermost cell) can be increased. Therefore, when the portable fuel cell is activated, the temperature distribution in the fuel cell body 3 can be effectively made uniform.

Further, this can be explained by Table 1.

[0027]

[Table 1] Table 1 shows the maximum temperature, minimum temperature and average temperature at the 9 temperatures of the above experiment. As shown in Table 1, the highest temperature in the fuel cell body 3 is 100 ° C. in the present example and the conventional example, but the lowest temperature in the fuel cell body 3 in this example is 75 ° C. The lowest temperature in the conventional example is 65 ° C, which is as high as 10 ° C. Further, the average temperature in the fuel cell main body 3 was also 80 ° C. in the conventional example, but increased to 85 ° C. in this example. Therefore, in this embodiment, the temperature difference between the maximum temperature and the minimum temperature in the fuel cell body 3 is small, and the temperature distribution in the fuel cell body 3 can be made more uniform than in the conventional example.

Further, the temperature inside the fuel cell body 3 is also related to the power generation voltage. This is demonstrated by the following experiment. In the experiment, the portable fuel cells of this example and the conventional example were used, and the cell voltage of each fuel cell main body 3 was measured 5 minutes after the start. The fuel cell body 3 is shown in FIG.
The voltage measurement cells were the first layer cell (outermost cell), the 16th layer cell (center cell) and the thirtieth layer cell (outermost cell).

[0029]

[Table 2] Table 2 shows the cell voltage in the above experiment. As shown in Table 2, the cell voltage of the 16th layer cell (center cell) is equal to 500 mV in this example and the conventional example,
The cell voltage of the 1st layer and 30th layer cell (outermost cell) in this Example is 470 mV, and the cell voltage of the 1st layer and 30th layer cell (outermost cell) in a prior art example is 40.
70 mV is higher than 0 mV.
Therefore, it is understood that the temperature distribution in the fuel cell main body 3 is made uniform and the power generation voltage of the entire fuel cell main body 3 is increased.

By the way, in this embodiment, the fuel cell main body 3
If the minimum voltage of the above is above a certain reference value, it is possible to output to the outside of the portable fuel cell. Therefore, in this embodiment, since the voltage of the outermost cell is higher than that in the conventional example, the startup time of the portable fuel cell can be shortened. (Embodiment 2) Next, a portable fuel cell according to Embodiment 2 will be described. The present embodiment is different from the first embodiment only in the arrangement of the start-up heater 34 in the fuel cell main body 3, and therefore the description of the overall configuration of the portable fuel cell is omitted.

FIG. 4 is a partially exploded view of the fuel cell main body 3 in the second embodiment. The pair of end plates 33 forming the fuel cell main body 3 are made of a heat insulating material, and the inner surface of each of the end plates 33 has a recess 51 formed almost entirely. The recess 51 includes the heater 34 for starting the end plate 3
3, the starting heater 34 is arranged so as to be embedded in the recess 51 without a gap. That is, the fuel cell body 3 is configured to be heated directly from the inside of each end plate 33, and is efficiently heat-exchanged with the starting heater 34. Therefore, it is possible to more effectively make the temperature distribution in the fuel cell body 3 uniform and shorten the startup time.

(Embodiment 3) The portable fuel cell according to Embodiment 3 is different from Embodiment 1 only in the arrangement of the starting heater 34 in the fuel cell body 3. FIG. 5 is an overall view of the fuel cell body 3 according to the third embodiment. On the outer surfaces of the pair of end plates 33 constituting the fuel cell main body 3, start-up heaters 34a and 3a are provided, respectively.
4b is arranged in a larger area on the air inlet side than on the air outlet side. That is, the arrangement ratio of the starting heater to the end plate 33 is higher on the air inlet side than on the air outlet side. For example, on the air inlet side, one strip-shaped heater 34a for activation is provided from the upper part to the lower part of each end plate 33, but on the air outlet side, the upper and middle parts of each end plate 33 are arranged. , A small-sized starting heater 34b is arranged in the lower three parts.

The air inlet side of the fuel cell body 3 is in contact with the low-temperature reaction air, so that the temperature is unlikely to rise, but the air outlet side is in contact with the exhaust air, so the temperature is likely to rise as compared with the air inlet side. Therefore, by disposing the start-up heater 34a in a large area on the air inlet side where it is difficult to raise the temperature,
The temperature on the air inlet side can be easily raised, and the temperature distribution in the fuel cell body 3 can be effectively made uniform.

(Embodiment 4) As shown in FIG. 6, a plurality of (nine in the illustrated example) small-sized heaters 34b for starting are arranged over the entire outer surface of the pair of end plates 33, and are not shown. It is also possible to individually control each starting heater 34b by the controller. In this case, the low temperature region in the entire end plate 33 can be selectively heated according to the temperature distribution in the fuel cell body 3, and the temperature in the fuel cell body 3 can be more effectively achieved. The distribution can be made uniform.

(Fifth Embodiment) The portable fuel cell according to the fifth embodiment is different from that of the first embodiment only in the shape of the starting heater 34 and the arrangement form in the fuel cell body 3. FIG. 7 is an overall view of the fuel cell main body 3 in the fifth embodiment. A pair of end plates 33 of the fuel cell body 3
Is made of, for example, a metal plate having good thermal conductivity such as aluminum. A heat insulating material (not shown) is arranged on the outer surface of each end plate 33 to suppress heat loss, and an electrically insulating material is formed on the inner surface of the end plate 33 to electrically insulate the separator 32. (Not shown) is arranged. Inside each end plate 33, a plurality of (four in the illustrated example) cylindrical spaces 52 are formed in the horizontal direction at substantially equal intervals.

The starting heater 34c is, for example, a 50 W rod-shaped (diameter 4 mm, length 70 mm) heater, and is inserted into each of the cylindrical spaces 52 from the direction indicated by a black arrow P3 in FIG. There is. That is, the starting heater 34c is embedded in each end plate 33 to heat the fuel cell main body 3. Here, since the heat insulating material is arranged on the outer surface of the end plate 33,
There is little heat loss to the outside of the fuel cell main body 3 of the startup heater 34c. Further, since the starting heater 34c is embedded inside the end plate 33, it does not come into contact with the fuel gas (hydrogen and air). Therefore, the fuel cell body 3 is effectively
The temperature distribution inside can be made uniform.

In this embodiment, the rod-shaped heater 34c is embedded in the end plate 33 in the horizontal direction. However, the present invention is not limited to this. For example, the rod-shaped heater 34c may be embedded in the vertical direction. It can also be embedded inside the end plate 33.

[0038]

As described above, according to the first aspect of the invention, the starting heater is arranged in contact with the fuel cell body along the outer surface of the fuel cell body. Therefore,
The heat is directly conducted to the fuel cell body, the temperature near the outer surface of the fuel cell body is easily raised, and the temperature distribution in the fuel cell body can be effectively made uniform.

Further, since the temperature inside the fuel cell body is easily raised, the minimum value of the cell voltage can be increased. Here, if the minimum voltage of the fuel cell main body becomes equal to or higher than a certain reference value, output to the outside is possible, so that the start-up time can be shortened. In addition, the water generated by the electrochemical reaction is quickly discharged without accumulating in the fuel cell body, so the fuel cell body is less damaged, power generation efficiency is improved, and the battery life is extended. You can

According to the second aspect of the present invention, a planar heater is used as the starting heater. Therefore, the start-up heater can be arranged in contact with the entire outer surface of the fuel cell body. Therefore, the fuel cell body is efficiently heated, and the temperature distribution in the fuel cell body can be effectively made uniform. Moreover, since the proportion of the startup heater in the housing can be reduced, the portable fuel cell can be made smaller and lighter.

In the third aspect of the invention, the starting heater is embedded in the recess formed in the inner surface of both end plates of the fuel cell body. Therefore, since the fuel cell main body is directly heated from the inside by the starting heater, the heat loss of the starting heater is small, and the temperature distribution can be effectively made uniform. Further, since the starting heater is arranged inside the fuel cell body, the shape of the fuel cell body is simplified. Therefore, the weight and simplification of the device can be achieved.

In the fourth aspect of the invention, since the starting heater is a rod-shaped heater which is usually commercially available, it is relatively inexpensive and economical. Further, since the start-up heater is embedded inside the end plate of the fuel cell body and the heat insulating material is disposed on the outer surface of the end plate, the heat generated by the heater is not lost to the outside. It is possible to efficiently heat the fuel cell main body with a small amount.

According to the fifth aspect of the invention, the arrangement ratio of the heaters for start-up is higher on the air inlet side than on the air outlet side. Here, the air inlet side of the fuel cell body is in contact with the low-temperature reaction air, so the temperature does not rise easily,
Since the air outlet side comes into contact with the exhaust air, the temperature tends to rise as compared with the air inlet side. Therefore, by disposing the start-up heater in a large area on the air inlet side where it is difficult to raise the temperature, it is possible to effectively raise the temperature on the air inlet side.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a portable fuel cell according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a diagram showing a fuel cell body in Example 1.

FIG. 4 is a partially exploded view showing a fuel cell main body according to a second embodiment.

FIG. 5 is a diagram showing a fuel cell main body according to a third embodiment.

FIG. 6 is a diagram showing a fuel cell main body according to a fourth embodiment.

FIG. 7 is a diagram showing a fuel cell main body according to a fifth embodiment.

FIG. 8 is a diagram showing temperature measurement positions in the fuel cell body used in the experiment.

FIG. 9 is a diagram showing a temperature distribution of outermost cells in a fuel cell body in Example 1 and a conventional example.

[Explanation of symbols]

 1 Case 2 Hydrogen Storage Alloy Tank 3 Fuel Cell Main Body 31 Cell 32 Separator 33 End Plate 34, 34a, 34b, 34c Starter Heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunori Yoshimoto 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Nobuyoshi Nishizawa 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5-5 Sanyo Electric Co., Ltd.

Claims (5)

[Claims] 1. A fuel cell main body for generating electric power by using hydrogen from a hydrogen supply source and air taken from the outside, and a fuel cell main body by using electric power generated by the fuel cell main body at the time of start-up in a portable case. A portable fuel cell equipped with a starting heater for heating, wherein the starting heater is arranged in contact with the fuel cell main body along an outer surface of the fuel cell main body. Portable fuel cell. 2. The portable fuel cell according to claim 1, wherein the starting heater is a planar heater. 3. The fuel cell main body comprises a cell having an anode and a cathode arranged in an electrolyte,
A hydrogen gas passage and a separator in which an air passage is formed are alternately laminated, and a laminated structure in which both ends thereof are pressed by a pair of end plates, wherein the starting heater is formed on an inner surface of the end plate. The portable fuel cell according to claim 1, wherein the portable fuel cell is embedded in a recess. 4. The portable fuel cell according to claim 1, wherein the starting heater is a rod-shaped heater and is embedded in a cylindrical space formed inside the end plate. 5. The portable fuel cell according to claim 1, wherein the start-up heater is arranged at a higher density on the air inlet side than on the air outlet side of the fuel cell main body.