JP2019121578A - Fuel cell system - Google Patents

Abstract

To improve the cooling performance of a heat exchanger of a fuel cell system.
A heat exchanger configured to perform heat exchange between a fuel cell and at least a product water as a cooling medium discharged from the fuel cell and a fluid so as to cool the fluid. And the heat exchanger 60 is a generated water storage portion 64 to which the generated water is supplied and stored, and an air supply device 80 for supplying air to the generated water storage portion 64. And the fluid supply unit 61 to which the fluid is supplied, and cools the fluid supplied to the fluid supply unit 61 by the latent heat of vaporization of the generated water stored in the generated water storage unit 64.
[Selected figure] Figure 1

Description

  The present invention relates to a fuel cell system.

  In Patent Document 1, as a conventional fuel cell system, water generated by an electrochemical reaction in a fuel cell stack (hereinafter referred to as “generated water”) is injected from an injector toward fins of a heat exchanger (radiator) Also, it is disclosed that the cooling performance of the heat exchanger is enhanced by the latent heat of vaporization of the generated water adhering to the fins.

JP 2007-242280 A

  However, in the case of the conventional fuel cell system described above, the surface temperature of the fin is 100 ° C. or less, and the generated water adhering to the fin is difficult to evaporate, and it is scattered without evaporating from the surface of the fin by traveling wind or the like. Produced water also increases. Therefore, the generated water can not be utilized sufficiently, and there is room for improvement in the cooling performance of the heat exchanger.

  The present invention has been made focusing on such a problem, and an object thereof is to improve the cooling performance of a heat exchanger using generated water.

  In order to solve the above problems, a fuel cell system according to an aspect of the present invention performs heat exchange between a fuel cell and at least generated water as a cooling medium discharged from the fuel cell and the fluid to obtain the fluid And a heat exchanger configured to be able to cool. The heat exchanger includes a product water storage unit to which product water is supplied and stored, an air supply device for supplying air to the product water storage unit, and a fluid supply unit to which a fluid is supplied. The system is configured to cool the fluid supplied to the fluid supply unit by the latent heat of vaporization of the generated water stored in the water storage unit.

  According to the fuel cell system according to this aspect of the present invention, the cooling performance of the heat exchanger utilizing the generated water can be improved.

FIG. 1 is a schematic configuration diagram of a fuel cell system according to a first embodiment of the present invention. FIG. 2 is a perspective view of the radiator according to the present embodiment. FIG. 3 is a schematic cross-sectional view of the radiator taken along line III-III of FIG. FIG. 4 is a schematic block diagram of a fuel cell system according to a second embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing the inside of the intercooler.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, similar components are denoted by the same reference numerals.

First Embodiment
FIG. 1 is a schematic block diagram of a fuel cell system 100 according to a first embodiment of the present invention.

  The fuel cell system 100 includes a fuel cell stack 10, a cathode gas supply / discharge device 20 for supplying / discharging a cathode gas (oxidant gas) to the fuel cell stack 10, a refrigerant for cooling the fuel cell stack 10 For example, a refrigerant circulating device 30 for circulating a long life coolant (LLC) is provided. In FIG. 1, an anode gas supply / discharge device for supplying / discharging anode gas (fuel gas) to / from fuel cell stack 10 and various electric components electrically connected to the output terminal of fuel cell stack 10 The electronic control unit for controlling the fuel cell system 100 is not shown because it is not a main part of the present invention.

  The fuel cell stack 10 is formed by stacking a plurality of fuel cell single cells (hereinafter referred to as "single cells") and electrically connecting the single cells in series. The fuel cell stack 10 receives a supply of an anode gas containing hydrogen and a cathode gas containing oxygen to generate power, and generates the generated power, for example, to various electric components such as a motor necessary to drive a vehicle. Supply. In the present embodiment, hydrogen is used as the anode gas, and air is used as the cathode gas.

  The cathode gas supply / discharge device 20 includes a cathode gas supply passage 21, an air cleaner 22, a cathode compressor 23, an intercooler 40, and a cathode off gas discharge passage 24. Hereinafter, the details of each component of the cathode gas supply / discharge device 20 will be described by defining the air cleaner 22 side as the upstream.

  The cathode gas supply passage 21 is a passage through which the cathode gas supplied to the fuel cell stack 10 flows, and includes an upstream side supply piping 21 a and a downstream side supply piping 21 b.

  The upstream side supply pipe 21 a is a pipe having one end connected to the air cleaner 22 and the other end connected to the high temperature gas inlet 41 of the intercooler 40 described later. The downstream side supply pipe 21 b is a pipe whose one end is connected to the low temperature gas outlet portion 42 of the intercooler 40 described later and the other end is connected to the cathode gas inlet portion 11 of the fuel cell stack 10.

  The air cleaner 22 is disposed in the atmosphere and removes foreign matter in the air as a cathode gas sucked into the upstream supply pipe 21a.

  The cathode compressor 23 is, for example, a centrifugal or axial flow turbo compressor, and is provided on the upstream side supply pipe 21 a. The cathode compressor 23 compresses and discharges the cathode gas drawn into the upstream supply pipe 21 a via the air cleaner 22.

  The intercooler 40 includes a high temperature gas inlet 41 and a low temperature gas outlet 42. The high temperature cathode gas introduced into the intercooler 40 from the high temperature gas inlet 41 is cooled by, for example, traveling air or cooling water. Then, the low temperature gas outlet 42 is discharged.

  The cathode off gas discharge passage 24 is a passage through which the cathode off gas discharged from the fuel cell stack 10 flows, and includes an upstream discharge pipe 24 a and a downstream discharge pipe 24 b. The cathode off gas is a mixed gas of excess oxygen not used for the electrochemical reaction of hydrogen and oxygen in the fuel cell stack 10 and an inert gas such as nitrogen, and the cathode off gas is an electrochemical reaction. The generated water (produced water and water vapor) is included.

  The upstream discharge pipe 24a is a pipe whose one end is connected to the cathode off gas outlet 12 of the fuel cell stack 10 and whose other end is connected to a gas inlet 711 of a gas-liquid separator 71 described later. The downstream discharge pipe 24b is a pipe whose one end is connected to a gas outlet 712 of a gas-liquid separator 71 described later and whose other end is open to the atmosphere.

  The refrigerant circulation device 30 includes a refrigerant circulation pipe 31, a refrigerant pump 32, a refrigerant cooling device 50, a radiator bypass pipe 33, and a bypass control valve 34.

  The refrigerant circulation pipe 31 is a pipe for circulating a refrigerant for cooling the fuel cell stack 10, one end of which is connected to the refrigerant inlet portion 13 of the fuel cell stack 10, and the other end of which is the refrigerant outlet portion of the fuel cell stack 10. Connected to 14 In the following, the refrigerant outlet portion 14 side is defined as the upstream of the refrigerant circulation pipe 31, and the refrigerant inlet portion 13 is defined as the downstream of the refrigerant circulation pipe 31.

  The refrigerant pump 32 is provided downstream of the refrigerant circulation pipe 31 and circulates the refrigerant.

  The refrigerant cooling device 50 includes a radiator 60, a generated water supply device 70, and an air supply device 80.

  The radiator 60 is provided on the refrigerant circulation pipe 31 upstream of the refrigerant pump 32. The radiator 60 according to the present embodiment includes a refrigerant that has flowed out from the refrigerant outlet portion 14 into the refrigerant circulation pipe 31, that is, a refrigerant that has been used for cooling the fuel cell stack 10 and has become relatively high temperature Not to be able to be cooled by the air sucked by (not shown), and further to be cooled by the latent heat of vaporization of water (produced water) generated by the electrochemical reaction of hydrogen and oxygen in the fuel cell stack 10 Configured to be The configuration of the radiator 60 according to the present embodiment will be described later with reference to FIGS. 2 and 3.

  The generated water supply device 70 is a device for supplying generated water to a water jacket 64 of a radiator 60 described later, and includes a gas-liquid separator 71 and generated water supply piping 72.

  The gas-liquid separator 71 includes a gas inlet 711, a gas outlet 712, and a liquid water outlet 713. The gas-liquid separator 71 separates the generated water from the cathode off-gas flowing into the interior from the gas inlet 711, discharges the separated product water from the liquid water outlet 713, and removes the cathode off-gas from which the product water is separated. The gas is discharged from the gas outlet 712.

  The generated water supply pipe 72 is a pipe having one end connected to the liquid water outlet 713 of the gas-liquid separator 71 and the other end connected to a water jacket 64 of a radiator 60 described later. The generated water in the cathode off gas separated by the gas-liquid separator 71 flows through the generated water supply pipe 72 and is supplied to the water jacket 64 of the radiator 60.

  The air supply device 80 is a device for supplying air to a water jacket 64 of a radiator 60 described later, and includes an air supply device 81 and an air supply pipe 82.

  The air supplier 81 is provided in the cathode gas supply passage 21 downstream of the cathode compressor 23. In the present embodiment, the air supply device 81 is provided on the upstream side supply piping 21a downstream of the cathode compressor 23, but may be provided on the downstream side supply piping 21b. The air supply device 81 is, for example, an injector driven using the compressed cathode gas discharged from the cathode compressor 23 as a power source, and injects outside air (air) from the air discharge port 81 a to form an air supply pipe 82. Configured to be able to supply

  The air supply pipe 82 is a pipe whose one end is connected to the air outlet 81 a of the air supplier 81 and whose other end is connected to a water jacket 64 of a radiator 60 described later. The air injected from the air outlet 81 a of the air supplier 81 flows through the air supply pipe 82 and is supplied to the water jacket 64 of the radiator 60.

  The radiator bypass piping 33 is a piping provided to circulate the refrigerant without passing through the radiator 60, and one end thereof is connected to the bypass control valve 34, and the other end is connected to the radiator 60 and the refrigerant pump 32. Is connected to the refrigerant circulation pipe 31 between them.

  The bypass control valve 34 is, for example, a thermostat, and is provided in the refrigerant circulation pipe 31 upstream of the radiator 60. The bypass control valve 34 switches the circulation path of the refrigerant according to the temperature of the refrigerant. Specifically, when the temperature of the refrigerant is higher than a preset reference temperature, the refrigerant flowing out from the refrigerant outlet portion 14 to the refrigerant circulation pipe 31 passes from the refrigerant inlet portion 13 through the radiator 60 to the fuel cell stack The refrigerant circulation path is switched so as to flow into the interior of 10. Conversely, when the temperature of the refrigerant is equal to or lower than the reference temperature, the refrigerant flowing out from the refrigerant outlet portion 14 to the refrigerant circulation piping 31 flows through the radiator bypass piping 33 without passing through the radiator 60 and the fuel cell from the refrigerant inlet 13 The refrigerant circulation path is switched so as to flow into the interior of the stack 10.

  FIG. 2 is a perspective view of the radiator 60 according to the present embodiment. FIG. 3 is a schematic cross-sectional view of the radiator 60 taken along line III-III of FIG.

  As shown in FIGS. 2 and 3, the radiator 60 includes an upper tank 61, a lower tank 62, a radiator core 63, and a water jacket 64.

  The upper tank 61 is a tank for a refrigerant formed at the top of the radiator core 63. The refrigerant flowing out of the refrigerant outlet portion 14 of the fuel cell stack 10 to the refrigerant circulation pipe 31, that is, the refrigerant used for cooling the fuel cell stack 10 and having a relatively high temperature is supplied to the upper tank 61.

  The radiator core 63 includes a plurality of refrigerant passages 631 such as a tube through which the refrigerant supplied to the upper tank 61 flows, and heat dissipating fins 632 attached to the surface of the refrigerant passage 631. The refrigerant flowing through the refrigerant passage 631 is cooled by the air passing around the refrigerant passage 631 from the front to the back of the radiator core 63.

  The lower tank 62 is a tank for a refrigerant formed at the bottom of the radiator core 63. The refrigerant flowing through the refrigerant passage 631 of the radiator core 63 and cooled is discharged from the lower tank 62 to the refrigerant circulation pipe 31 and introduced into the refrigerant inlet portion 13 of the fuel cell stack 10.

  The water jacket 64 is formed outside the upper tank 61 so as to cover the outer wall 611 (see FIG. 3) of the upper tank 61.

  As described above, the generated water supply pipe 72 is connected to the water jacket 64, and the generated water in the cathode off gas separated by the gas-liquid separator 71 is supplied and stored therein. Thus, the heat of the refrigerant supplied into the upper tank 61 can be transmitted to the generated water in the water jacket 64 through the outer wall 611 of the upper tank 61. That is, heat exchange is performed between the generated water in the water jacket 64 and the refrigerant in the upper tank 61, and the refrigerant in the upper tank 61 can be cooled by the latent heat of vaporization of the generated water in the water jacket 64. ing.

  Here, in order to increase the cooling efficiency of the refrigerant in the upper tank 61, it is effective to promote the evaporation of the generated water in the water jacket 64. Therefore, in the present embodiment, the air supply pipe 82 is connected to the water jacket 64, outside air introduced into the air supply pipe 82 is supplied to the inside through the air supply device 81, and the water jacket 64 is provided at the top of the water jacket 64. The water vapor generated in the water jacket 64 can be released from the water vapor outlet 641.

  As a result, outside air (air with a relatively low water vapor concentration) can be supplied into the war jacket, and the generated water in the water jacket 64 can be agitated. Therefore, since the water vapor concentration in the air in the water jacket 64 can be kept low, evaporation of the generated water in the water jacket 64 can be promoted. By evaporating part of the generated water in the water jacket 64, the remaining generated water can be cooled by the latent heat of vaporization at that time. Therefore, the heat of the refrigerant in the upper tank 61 can be well transmitted to the generated water in the water jacket via the outer wall 611 of the upper tank 61. Therefore, the cooling efficiency of the refrigerant in the upper tank 61 can be increased.

  The fuel cell system 100 according to the present embodiment described above includes the fuel cell stack 10 (fuel cell), at least generated water as a cooling medium discharged from the fuel cell stack 10, and a refrigerant (fluid which cools the fuel cell stack 10). And a radiator 60 (heat exchanger) configured to be able to perform heat exchange with each other to cool the refrigerant. The radiator 60 includes a water jacket 64 (produced water storage portion) in which product water is supplied and stored, an air supply device 80 for supplying air to the water jacket 64, and an upper tank 61 (fluid supply in which a refrigerant is supplied). , And is configured to cool the refrigerant supplied to the upper tank 61 by the latent heat of vaporization of generated water stored in the water jacket 64.

  Thus, the generated water discharged from the fuel cell stack 10 is supplied to the water jacket 64 of the radiator 60 and stored, and the refrigerant supplied to the upper tank 61 by the latent heat of vaporization of the generated water stored in the water jacket 64 is stored. By cooling, generated water can be used for cooling the refrigerant without wasting it. Therefore, the cooling performance of the radiator 60 can be improved.

Further, external air (air having a relatively low water vapor concentration) is supplied into the water jacket 64 to agitate the generated water in the water jacket 64 to keep the water vapor concentration in the air in the water jacket 64 low. Evaporation of generated water into the air in the water jacket 64 can be promoted. Therefore, since the cooling efficiency of the refrigerant in the upper tank 61 can be increased, the cooling performance of the radiator 60 can be further improved.
Second Embodiment
Next, a second embodiment of the present invention will be described. The present embodiment is different from the first embodiment in that the intercooler 40 is configured to cool the cathode gas using the latent heat of vaporization when the generated water is evaporated. The differences will be mainly described below.

  FIG. 4 is a schematic block diagram of a fuel cell system 100 according to a second embodiment of the present invention.

  The intercooler 40 according to the present embodiment includes a high temperature gas inlet 41, a low temperature gas outlet 42, a first internal flow passage 43 communicating the high temperature gas inlet 41 and the low temperature gas outlet 42, and a liquid water inlet 44 , The water vapor outlet 45, and the second internal flow passage 46 connecting the liquid water inlet 44 and the water vapor outlet 45, and compressed by the cathode compressor 23 using the latent heat of vaporization of the generated water to a high temperature Configured to cool the cathode gas.

  In the present embodiment, the other end of the generated water supply pipe 72 is connected to the liquid water inlet 44 of the intercooler 40, and the generated water in the cathode off gas separated by the gas-liquid separator 71 is supplied to the generated water. It flows through the pipe 72 and is introduced into the second internal flow path 46 from the liquid water inlet 44. Further, the other end of the air supply pipe 82 is also connected to the liquid water inlet 44 of the intercooler 40 so that the outside air can be introduced into the second internal flow passage 46.

  FIG. 5 is a schematic cross-sectional view showing the inside of the intercooler 40 according to the present embodiment.

  As shown in FIG. 5, a plurality of first internal channels 43 and second internal channels 46 partitioned by the partition wall 47 are alternately formed in the vertical direction in the drawing, inside the intercooler 40, The heat of the cathode gas flowing through the internal flow passage 43 can be transferred to the generated water supplied into the second internal flow passage 46 through the partition wall 47.

  Further, in the first internal flow passage 43 and the second internal flow passage 46, the water vapor generated in the second internal flow passage 46 by heat exchange with the cathode gas flowing in the first internal flow passage 43 is the first internal flow passage 43. Each flow path is independent so that it does not flow into the That is, the water vapor generated in the second internal flow passage 46 is not used for humidifying the cathode gas inside the intercooler 40, and from the second internal flow passage 46 to the outside of the intercooler 40 via the water vapor discharge pipe 91. It is supposed to be discharged.

  The cathode gas supplied to the interior of the intercooler 40 from the high temperature gas inlet 41 is distributed substantially uniformly and flows into the first internal flow path 43, and in the example shown in FIG. The cathode gas is flowing through the first internal flow channel 43 from the back toward the paper surface. Further, a plurality of fins 48 extending from the partition wall 47 are formed in the first internal flow channel 43, and heat of the cathode gas can be efficiently transmitted to the partition wall 47 through the fins 48. ing.

  The generated water supplied from the liquid water inlet portion 44 to the inside of the intercooler 40 is distributed substantially equally and stored in the second internal flow path 46. The water supplied to the second internal flow passage 46 becomes water vapor due to heat exchange with the cathode gas through the partition wall 47, and in the example shown in FIG. It flows through the internal flow passage 46 and is discharged from the water vapor outlet 45. As described above, in the present embodiment, the cathode gas and the water vapor flow so as to face each other in the intercooler 40, but the present invention is not limited to this and may flow in the same direction.

  When the cathode gas flows in the first internal flow channel 43, the heat of the cathode gas is transferred to the partition 47, and the temperature of the partition 47 rises. When the temperature of the partition 47 exceeds the boiling point of the water flowing in the second internal channel 46, the water in the second internal channel 46 in contact with the partition 47 is boiled, and the temperature of the partition 47 is caused by the vaporization latent heat at that time. The rise can be suppressed to a certain temperature. That is, the temperature rise of the temperature of the partition wall 47 can be suppressed to the temperature near the boiling point of water which is lower than the temperature of the cathode gas. Therefore, the temperature difference between the cathode gas and the partition 47 can be maintained at a certain temperature difference, and the heat of the cathode gas can be continuously and efficiently transferred to the partition 47 to cool the cathode gas.

  Further, in the present embodiment, outside air (air having a relatively low water vapor concentration) is introduced from the liquid water inlet 44 into the second internal flow passage 46 of the intercooler 40 via the air supply pipe 82. Here, in the second internal flow channel 46, generated water is stored in the space below it, and air containing water vapor is present in the space above it. In order for the generated water in the second internal flow passage 46 to evaporate, the amount of water vapor in the space above this needs to be less than the amount of saturated water vapor, but outside air is supplied to the second internal flow passage 46 as in this embodiment. By introducing it, it is possible to suppress the amount of water vapor in the upper space from becoming saturated water vapor. Therefore, since the evaporation of the generated water can be further promoted, the cathode gas can be cooled more efficiently. Further, by introducing the outside air, the generated water in the second internal flow path 46 can also be stirred, and thereby, the contact between the generated water and the outside air can be promoted to promote the evaporation.

  The fuel cell system 100 according to the present embodiment described above includes a fuel cell stack 10 (fuel cell), at least generated water as a cooling medium discharged from the fuel cell stack 10, and a cathode gas supplied to the fuel cell stack 10. An intercooler 40 (heat exchanger) configured to perform heat exchange with (fluid) to cool the cathode gas. The intercooler 40 is supplied with a second internal flow passage 46 (produced water storage portion) in which generated water is supplied and stored, an air supply device 80 for supplying air to the second internal flow passage 46, and a cathode gas. And cooling the cathode gas supplied to the first internal flow path 43 by the latent heat of vaporization of the generated water stored in the second internal flow path 46. Is configured.

  Thus, the generated water can be used without waste for cooling the cathode gas, and by introducing air into the generated water in the second internal flow path 46, evaporation of the generated water can be promoted. Therefore, since the cathode gas can be cooled efficiently, the cooling performance of the intercooler 40 can be improved.

  As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

  For example, in the above embodiments, fins may be provided on the outer wall of the upper tank 61 to enhance the heat radiation performance to the generated water in the water jacket 64. When air is introduced into the water jacket 64, the air may be diffused and introduced by, for example, a porous body (diffuser).

  In the above embodiments, the outside air is introduced into the water jacket 64 or the second internal flow passage 46 by the injector 81. However, a part of the cathode gas may be branched and introduced. Thus, the outside air can be introduced into the water jacket 64 or the second internal flow passage 46 with a simpler configuration than the fuel cell system 100 described in each of the above embodiments.

10 Fuel cell stack (fuel cell)
40 intercooler (heat exchanger)
43 1st internal flow path (fluid supply part)
46 2nd internal flow path (generated water storage part)
60 radiator (heat exchanger)
61 Upper tank (fluid supply part)
64 Water jacket (generated water reservoir)
80 Air supply device 100 Fuel cell system

Claims (1)

With fuel cells,
A heat exchanger configured to perform heat exchange between at least a product water as a cooling medium discharged from the fuel cell and the fluid to cool the fluid;
A fuel cell system comprising
The heat exchanger is
A generated water storage unit to which the generated water is supplied and stored;
An air supply device for supplying air to the generated water reservoir;
A fluid supply unit to which the fluid is supplied;
Equipped with
The fluid supplied to the fluid supply unit is cooled by the latent heat of vaporization of the product water stored in the product water storage unit,
Fuel cell system.

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