JP6468209B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system including a fuel cell and a compressor that supplies oxygen gas to the fuel cell.

  Conventionally, a fuel cell system includes a fuel cell, and a gas supply pipe for supplying oxygen gas to the current cell is connected to the fuel cell. Here, if impurities are mixed in the gas supplied to the fuel cell, the impurities are brought into the fuel cell.

  In view of such a point, for example, in Patent Document 1, a gas supply pipe for supplying oxygen gas is connected to the fuel cell, and impurities in the oxygen gas easily flow in the middle of the gas supply pipe. A closed branch branched from the gas supply pipe in the direction and closed at the end is connected.

  According to the fuel cell system according to Patent Document 1, by providing the closed branch pipe branched from the gas supply pipe, the impurities can be captured by the closed branch pipe, so that the impurities can be prevented from flowing into the fuel cell. .

JP 2005-267987 A

  However, when supplying oxygen gas to the fuel cell, since a large flow rate of oxygen gas is supplied to the fuel cell using a compressor, as shown in Patent Document 1, if a closed branch pipe branched from the gas supply pipe is provided, The pressure loss of oxygen gas toward the fuel cell becomes large.

  The present invention has been made in view of the above points, and an object thereof is to suppress the flow of impurities in the oxygen gas into the fuel cell while suppressing the pressure loss of the oxygen gas toward the fuel cell. It is an object of the present invention to provide a fuel cell system capable of performing the above.

  In view of the above problems, a fuel cell system according to the present invention is a fuel cell system including a fuel cell and a compressor that supplies oxygen gas to the fuel cell, and the fuel cell system is provided between the fuel cell and the compressor. Is connected to a gas supply pipe for supplying oxygen gas from the compressor to the fuel cell, and the gas supply pipe is formed with a bent portion bent at a predetermined curvature. The flow path for oxygen gas passes from the first position at the bending center of the bent portion to the bent end on the fuel cell side of the bent portion, and further extends to a distance corresponding to the pipe diameter of the gas supply pipe. In the section up to the second position, the baffle plate is disposed so as to extend from the inner wall on the radially outer side of the bent portion toward the inner side of the bent portion among the inner walls through which oxygen gas flows in the bent portion. And said that you are.

  According to the present invention, the impurities in the oxygen gas passing through the gas supply pipe in which the bent portion is formed pass through the outer side in the radial direction of the bent portion in the section from the first position to the second position described above by centrifugal force. easy. In the present invention, in this section, the baffle plate is disposed from the inner wall on the radially outer side of the bent portion toward the inside of the bent portion, so that impurities can be captured by the baffle plate.

  Further, in the present invention, since only a part of the flow path of the gas supply pipe is restricted by the baffle plate without branching the gas supply pipe, compared with the case where the gas supply pipe is branched, The pressure loss of oxygen gas toward the fuel cell can be reduced.

  In this way, according to the present invention, it is possible to suppress the impurities in the oxygen gas from flowing into the fuel cell while suppressing the pressure loss of the oxygen gas toward the fuel cell.

1 is a schematic diagram of a fuel cell system according to an embodiment of the present invention. It is the schematic diagram which showed the principal part of the fuel cell system shown in FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. (A) is a general view of a model in the vicinity of the bent portion in the analysis for confirming the effect of the baffle plate according to the present embodiment, and (b) is an enlarged view of the vicinity of the baffle plate of (a). It is the figure which showed the analysis result in conditions (A)-(D) using the model shown to Fig.4 (a). It is the graph which showed the relationship between the flow volume in conditions (A)-(D) and a capture rate. It is a graph of the analysis result which showed the relationship between flow volume and pressure loss.

  As shown in FIG. 1, the fuel cell system 1 according to the present embodiment includes at least a fuel cell 2 and a compressor (turbo compressor) 3 that supplies gas to the fuel cell 2. A gas supply pipe 4 for supplying oxygen gas from the compressor 3 to the fuel cell 2 is connected between the fuel cell 2 and the compressor 3.

  The compressor 3 includes a compression chamber 31 that pumps a gas containing oxygen (oxygen gas) to the fuel cell 2, and an impeller 32 that compresses the oxygen gas is disposed in the compression chamber 31. A motor 33 that rotationally drives the impeller 32 is disposed at a position adjacent to the compression chamber 31, and the motor 33 is accommodated in the motor chamber 34.

  When supplying oxygen gas, the motor 33 that drives the compressor 3 and drives and rotates the impeller 32 rotates at a high speed of about 100,000 rpm. For this reason, since the motor 33 easily generates heat at a high temperature, the motor chamber 34 is connected to the cooling system 51 in order to cool the bearing that supports the motor 33 and the motor 33 itself.

  The cooling system 51 cools the motor 33 and the like by circulating cooling oil to the motor chamber 34. Oil from the cooling system 51 is pumped to the motor chamber 34 via the oil pump 52, and oil returning from the motor chamber 34 is cooled by the oil cooler 53.

  The motor chamber 34 is provided with a mechanical seal or the like to prevent oil from leaking into the compression chamber 31. However, as described above, since the motor 33 rotates at a high speed, a slide such as a mechanical seal or the like is provided. A small amount of oil may leak into the compression chamber 31 from the moving part.

  Further, normally, the pressure in the compression chamber 31 is kept higher than the pressure in the motor chamber 34, but the pressure in the motor chamber 34 becomes high as the temperature in the motor chamber 34 rises. Sometimes. Thereby, it is assumed that oil flows from the motor chamber 34 into the compression chamber 31.

  In addition to this, when the rotational speed of the motor 33 is decelerated, the pressure in the compression chamber 31 may become negative, and the pressure in the motor chamber 34 is relative to the pressure in the compression chamber 31. Can be expensive. Also in this case, it is assumed that oil flows from the motor chamber 34 into the compression chamber 31.

  Even if the air cleaner 55 is provided on the upstream side of the compression chamber 31 of the compressor 3, such oil flows into the fuel cell 2 through the gas supply pipe 4 as particles of about 100 μm. In the present embodiment, the following structure is employed in order to suppress not only the impurities contained in the oxygen gas sucked by the compressor 3 but also such oil from flowing into the fuel cell 2.

  Specifically, in this embodiment, as shown in FIG. 2, the gas supply pipe 4 is a pipe obtained by bending a straight pipe into 90 °. More specifically, the gas supply pipe 4 includes a straight pipe portion 41 connected to the compressor 3 and a bent portion that is continuous from the straight pipe portion 41 and bent at 90 ° with a predetermined curvature with respect to the straight pipe portion 41. 42 and a straight pipe portion 43 which is continuous from the bent portion 42 and connected to the fuel cell 2 is formed.

  Here, since impurities such as oil in the oxygen gas flowing through the gas supply pipe 4 have a specific gravity greater than that of the oxygen gas, they easily pass through the outside of the bent portion 42 in the radial direction due to centrifugal force. More specifically, from the first position 42a at the bending center of the bent portion 42, it passes through the bending end 42b on the fuel cell 2 side of the bent portion 42 and further extends to a distance corresponding to the pipe diameter D of the gas supply pipe 4. Further, in the section up to the second position 42c, the impurities easily pass the radially outer side of the bent portion 42.

  Accordingly, the baffle plate 47 extends from the inner wall 45a on the radially outer side of the bent portion 42 toward the inner side of the bent portion 42 between the first position 42a and the second position 42c where the impurities easily pass. It is good to arrange. Thereby, the baffle plate 47 can suitably capture impurities contained in the oxygen gas.

  In the present embodiment, as shown in FIG. 2, in the flow path through which the oxygen gas flows in the bent portion 42, the bent end 42 b on the fuel cell side of the bent portion 42 is bent from the inner wall 45 a on the radially outer side of the bent portion 42. A baffle plate 47 is disposed so as to extend inward of the portion 42. Since the baffle plate 47 is disposed at such a position, impurities can be captured by the baffle plate 47.

  Further, in the present embodiment, the gas supply pipe 4 is not branched, but only a part of the flow path of the gas supply pipe 4 is restricted by the baffle plate 47. Compared with the case where it was made, the pressure loss of the oxygen gas which goes to the fuel cell 2 can be reduced.

  Here, as shown in FIG. 3, the pressure loss of the oxygen gas toward the fuel cell 2 can be more effectively suppressed by setting the height H of the baffle plate 47 to ¼ or less of the pipe diameter D. it can.

  Further, when the baffle plate 47 captures oil as an impurity, a porous or fibrous material capable of absorbing a liquid such as oil may be used. Further, the surface roughness of the baffle plate 47 may be made larger than the surface roughness of the inner wall surface of the gas supply pipe 4 so that the oil once adhered to the surface of the baffle plate 47 can be held.

  FIG. 4A is an overall view of a model in the vicinity of the bent portion in the analysis for confirming the effect of the baffle plate 47 according to the present embodiment, and FIG. 4B is a baffle plate 47 of FIG. FIG.

  As shown in FIG. 4A, in this analysis, the gas supply pipe 4 having an inner diameter of 40 mm is assumed, the straight pipe portions 41 and 43 have a length of 100 mm, and the bent portion 42 has a radius of the bent portion 42. The inner side (inner circumferential side) in the direction is bent at 90 ° with a radius of curvature of 50 mm.

  The baffle plate 47 is arranged at the bending end 42b on the fuel cell side of the bent portion 42, similarly to the gas supply pipe 4 shown in FIG. In this model, the thickness t of the baffle plate 47 is 5 mm, and the height H is 10 mm. The height H of the baffle plate 47 corresponds to a quarter of the pipe diameter D.

Using such a model,
Condition (A): impurity particle size 100 μm, oxygen gas flow rate 450 NL / min,
Condition (B): impurity particle size 100 μm, oxygen gas flow rate 5700 NL / min,
Condition (C): impurity particle size 10 μm, oxygen gas flow rate 450 NL / min,
Condition (D): Impurity particle size of 10 μm, oxygen gas flow rate of 5700 NL / min,
The analysis was performed under the following four conditions. The result is shown in FIG. FIG. 5 is a diagram showing analysis results under conditions (A) to (D) using the model shown in FIG.

Furthermore, the trapping rate of impurities (particles) by the baffle plate was calculated using the following formula.
Capture rate (%) = number of impurities (particles) captured by baffle plates / number of released particles × 100

  The results are shown in FIG. 5 and FIG. FIG. 6 is a graph showing the relationship between the flow rate and the capture rate under the conditions (A) to (D).

  Furthermore, the pressure loss of oxygen gas (pressure loss) was calculated at a flow rate of oxygen gas of 450 NL / min and 5700 NL / min. The result is shown in FIG. FIG. 7 is a graph of analysis results showing the relationship between flow rate and pressure loss.

(result)
As shown in FIGS. 5 and 6, the conditions (A) and (B) where the particle size of the impurity is 100 μm are compared with the conditions (C) and (D) where the particle size of the impurity is 10 μm. The capture rate by was high. This is considered to be because if the impurity is large, centrifugal force acts on the impurity at the bent portion due to the inertia of the impurity, and the impurity is directed to the inner wall on the radially outer side of the bent portion where the baffle plate is disposed. When the impurity is oil, the particle size is about 100 μm, so that the conditions (A) and (B) are met, and the impurity can be efficiently captured by the baffle plate.

  Further, the capture rate by the baffle plate was higher in the condition (D) than in the condition (C). This is because, under the condition (C), since the flow rate is large, the linearity of the impurities in the straight pipe portion is high, and the impurities easily collide with the inner wall on the radially outer side of the bent portion.

  It should be noted that the condition (A) has a higher capture rate by the baffle plate than the condition (B). The analysis shows that the impurities colliding with the baffle plate bounced back in the condition (B) where the flow rate is large. It is thought that. When the impurity is oil, it is considered that such a phenomenon hardly occurs. Therefore, when capturing the oil with an actual machine, the condition (B) is more dependent on the baffle plate than the condition (A). It is believed that the capture rate will increase.

  Further, as shown in FIG. 7, there is almost no pressure loss when the flow rate of oxygen gas is 450 NL / min, and the pressure loss is 1 MPa (1000 Pa) even when the flow rate of oxygen gas is 5700 NL / min. Degree. Therefore, it is considered that the influence of the pressure loss of oxygen gas toward the fuel cell is small due to the baffle plate.

  Although the embodiment of the present invention has been described in detail above, the specific configuration is not limited to this embodiment, and even if there is a design change within a scope not departing from the gist of the present invention, they are not limited to this embodiment. It is included in the invention.

  1: fuel cell system, 2: fuel cell, 3: compressor, 4: gas supply piping, 41, 43: straight pipe portion, 42: bent portion, 42a: first position, 42b: terminal, 42c: second position, 45: inner wall, 45a: radially inner wall, 47: baffle plate, D: pipe diameter.

Claims (1)

A fuel cell system comprising a fuel cell and a compressor for supplying oxygen gas to the fuel cell,
A gas supply pipe for supplying oxygen gas from the compressor to the fuel cell is connected between the fuel cell and the compressor,
The gas supply pipe is formed with a bent portion bent at a predetermined curvature,
The flow path of the bent portion through which the oxygen gas flows passes from the first bending center of the bent portion to the bent end of the bent portion on the fuel cell side, and further to the pipe diameter of the gas supply pipe. In the section to the second position extended to the corresponding distance, the inner wall through which the oxygen gas flows in the bent portion extends from the inner wall on the radially outer side of the bent portion toward the inner side of the bent portion. A fuel cell system, wherein a baffle plate is disposed.

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