Fuel cell hydrogen injection mixer

Abstract

The invention relates to the field of fuel cells, and particularly discloses a fuel cell hydrogen injection mixer. Comprising a nozzle and a valve body, a receiving chamber, a mixing chamber and a diffusion chamber are sequentially arranged in the valve body in the axial direction, the nozzle communicates with the receiving chamber, an injection air inlet is formed in the side wall of the receiving chamber, a diffusion chamber is arranged on the side, away from the mixing chamber, of the diffusion chamber, and the bottom of the diffusion chamber is lower than the bottom of the end, away from the mixing chamber, of the diffusion chamber; a turbulent flow ring is arranged in the diffusion chamber and located on the lower portion of the diffusion chamber. According to the hydrogen injection mixer of the fuel cell in the scheme, the problem that two cells in front of an anode are flooded can be solved under the condition that no extra space is occupied.

Description

Technical Field

[0001] The invention relates to the field of fuel cells, and in particular to a hydrogen injection mixer for a fuel cell. Background Art

[0002] Since traditional fossil energy power generation will bring about problems such as energy security, environmental pollution, and climate change, new energy such as solar energy and wind energy are currently used as alternatives to fossil energy power generation. However, solar energy and wind energy have uneven distribution and unstable power, resulting in waste such as "abandoning wind" and "abandoning electricity". The hydrogen used in fuel cells can be used as a good energy storage medium to store the above-mentioned electrical energy that cannot be incorporated into the power grid in the form of chemical energy, reducing the waste of electrical energy.

[0003] In order to make the hydrogen and oxygen in the fuel cell fully react and improve the reaction efficiency, an excess of hydrogen is generally introduced into the anode of the stack. The unreacted hydrogen will be mixed with saturated water vapor and a small amount of nitrogen to form an ejector fluid, which will be discharged from the anode of the stack and flow back to the anode inlet of the stack through the hydrogen return system. The hydrogen return system re-introduces hydrogen into the stack through a circulation pump or an ejector, but the ejector fluid is in a high temperature and high humidity state. When a circulation pump is used, the high humidity and high temperature ejector fluid circulated by the pump is mixed with the new hydrogen from the hydrogen supply component through the pipeline. Due to the low temperature of the new hydrogen, the saturated water vapor in the ejector fluid will be liquefied during the mixing; when an ejector is used, the new hydrogen and the refluxed ejector fluid are mixed in the ejector, and the temperature of the new hydrogen will be further reduced after the ejector nozzle is decompressed and accelerated, which further aggravates the problem of water vapor liquefaction in the ejector fluid. After the water vapor is liquefied, the liquefied water will flow into the battery stack, causing the first one or two batteries in the stack to be "flooded" and the voltage to be significantly lower than that of other batteries, which is the "single low" phenomenon and seriously affects the life of the battery stack.

[0004] There are currently two main methods to solve the problems of "flooding" and "single low" in the first two cells of the anode. One is to add a few fake cells at the front end of the battery stack. The fake cells do not participate in power generation but retain the flow channel. Liquid water enters the fake cells and is stored before entering the battery stack, thereby ensuring the normal operation of the subsequent batteries. This method undoubtedly increases the cost and volume of the battery stack. The second is to preheat the new hydrogen, increase the temperature of the new hydrogen, reduce the temperature difference between it and the ejected fluid, and reduce the degree of liquefaction of water vapor. However, the current conventional scheme shows that under limited volume and contact area, the heat exchange area of ​​the new hydrogen is very small, and its heating capacity is limited. Therefore, it cannot solve the problem well. Increasing the volume and contact area will undoubtedly make the entire device too large and increase the cost.

[0005] Although there is currently a patent as disclosed in application number CN202322814877.1, a hydrogen fuel cell system flooding prevention system and its gas-water mixing device, which uses a gas-water mixing device connected in sequence, by respectively arranging a first steam-water separator and a second steam-water separator on the front and rear sides of the fuel cell stack, after the high-temperature and high-humidity injection fluid is mixed with the low-temperature dry hydrogen, the liquid water therein is separated through the in-stack steam-water separator, thereby reducing the liquid water in the gas entering the fuel cell stack. However, the added first steam-water separator will also take up a certain amount of space, resulting in the entire device being too large in size and having a high cost. Summary of the invention

[0006] The present invention aims to provide a fuel cell hydrogen injection mixer to solve the problem of water flooding of the first two cells of the anode without taking up extra space.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a fuel cell hydrogen injection mixer, including a nozzle and a valve body, wherein a receiving chamber, a mixing chamber and a diffusion chamber are sequentially arranged in the valve body along the axial direction, the nozzle is connected to the receiving chamber, and an injection air inlet is arranged on the side wall of the receiving chamber, a diffusion chamber is arranged on the side of the diffusion chamber away from the mixing chamber, and the bottom of the diffusion chamber is lower than the bottom of the end of the diffusion chamber away from the mixing chamber; a spoiler ring is arranged in the diffusion chamber, and the spoiler ring is located at the lower part of the diffusion chamber.

[0008] The beneficial effects of this program are:

[0009] 1. When the ejector mixer is working, the high-pressure new hydrogen forms a high-speed airflow after adiabatic expansion through the nozzle. Therefore, in the mixing chamber, the high-speed airflow accelerates the low-speed ejector fluid under the action of gas viscosity and shear force and mixes it to the diffusion chamber. At the same time, since the temperature of the new hydrogen is relatively low and the temperature is further reduced after adiabatic expansion through the nozzle, when the ejector fluid is mixed with the new hydrogen with a lower temperature, the saturated water vapor will liquefy. According to the Bernoulli principle, a low-pressure area is formed in the mixing chamber, thereby continuously sucking the ejector fluid from the anode of the battery stack. Finally, the mixed gas formed by the new hydrogen and the ejector fluid begins to slow down and increase pressure in the diffusion chamber.

[0010] When the liquid water formed by the liquefaction of water vapor in the mixed gas flows with the mixed gas, under the influence of gravity and the surface tension of the liquid water, the liquid water in the ejector presents Figure 1Distribution, that is, there are fine droplets in the upper part of the flow channel, larger droplets in the middle part of the flow channel, and large water clusters gather in the lower part of the flow channel. In this scheme, a diffusion chamber is set at the rear side of the diffusion chamber. Since the bottom of the diffusion chamber is lower than the bottom of the diffusion chamber, the water droplets and water clusters are broken up to form free fluids after leaving the diffusion chamber and fall to the bottom of the diffusion chamber. At the same time, the water droplets flow with the mixed gas, and then the water droplets are dispersed into small water droplets with smaller particle sizes under the collision with the spoiler ring and the action of eddy currents, and mixed with the mixed gas. Therefore, there are no more concentrated liquid water droplets in the mixed gas entering the battery stack, and the small water droplets with smaller particle sizes can continue to flow to the battery on the rear side with the mixed gas after entering the battery stack together with the mixed gas, so as to be evenly distributed in the multiple batteries in the battery stack, rather than completely gathered in the first one or two batteries of the battery stack, causing the first one or two batteries to be flooded. After the small water droplets are distributed in multiple batteries, the amount of water in each battery is small, which will not cause the battery to be "flooded".

[0011] Compared with the prior art which adds dummy batteries and sets a steam-water separator, this solution only adds a diffusion chamber and a spoiler ring to the ejector mixer, and does not increase the volume of the fuel cell stack. Compared with heating the new hydrogen, in addition to not increasing the volume of the fuel cell stack, it does not require energy consumption for heating and related control procedures, so the cost of this solution is lower.

[0012] 2. The bottom of the diffusion chamber in this scheme is lower than the bottom of the diffusion chamber, so the cross-sectional area of ​​the diffusion chamber is larger than the cross-sectional area of ​​the diffusion chamber. When the mixed gas from the diffusion chamber enters the diffusion chamber with a larger cross-section, a large number of vortices will be formed at the inlet wall of the diffusion chamber close to one end of the diffusion chamber under the action of gas viscosity, which will further convolute and mix the falling liquid water, thereby forming water droplets more quickly.

[0013] 3. After the gathered water droplets pass through the spoiler ring, they will be "thrown" upwards under the action of the spoiler ring, which will disperse the water droplets into smaller water droplets and further promote the mixing of the small water droplets with the mixed gas, thereby preventing the small water droplets from re-aggregating into water droplets and reducing the re-aggregation of liquid water.

[0014] 4. The spoiler ring in this solution is located at the lower part of the diffusion chamber. When liquid water gathers into water droplets, under the action of gravity, the larger the water droplets, the more they fall downward. Therefore, the water droplets closer to the bottom of the diffusion chamber have a larger particle size. The spoiler ring in this embodiment can better disperse water droplets with larger particle sizes, thereby improving the dispersion effect of the water droplets.

[0015] Furthermore, the cross sections of the diffusion chamber and the pressure diffuser chamber are both circular, and the diffusion chamber is coaxial with the pressure diffuser chamber, and the diameter of the diffusion chamber is larger than the diameter of the pressure diffuser chamber at one end away from the mixing chamber.

[0016] The beneficial effect of this solution is that in this solution, when the mixed gas enters the diffusion chamber from the diffusion chamber, the mixed gas can form a vortex around the end of the diffusion chamber, thereby further promoting the liquid water to converge into water droplets.

[0017] Furthermore, the spoiler ring is in a circular ring shape, and a notch is provided on the upper part of the spoiler ring.

[0018] The beneficial effect of this solution is that the spoiler ring in this solution can better disperse the water droplets and promote them to mix with the mixed gas, and reduce the influence of the spoiler ring on the increase of the flow resistance of the flow channel while ensuring the function of the spoiler ring.

[0019] Furthermore, the central angle corresponding to the spoiler ring is 180°.

[0020] The beneficial effect of this solution is: after testing, the spoiler ring in this solution has the best dispersion effect on water droplets.

[0021] Furthermore, a slope is provided on the side wall of the spoiler ring facing the diffuser chamber, and the slope is an inclined surface inclined from an end away from the diffuser chamber toward a center of the spoiler ring.

[0022] The beneficial effect of this solution is that the slope guides the water droplets gathered at the bottom of the diffusion chamber, better "scatters" the water droplets, and further promotes uniform mixing of the water droplets and the mixed gas.

[0023] Furthermore, the cross section of the spoiler ring along the axial direction is a right triangle, the surface where the hypotenuse of the spoiler ring is located is a slope, and the surface where one right-angled side of the spoiler ring is located is in contact with the diffusion chamber.

[0024] The beneficial effect of this scheme is that the spoiler ring in this scheme forms a flow channel with a sudden change in diameter on the back side of the slope (perpendicular to the position of the other right-angled side of the diffusion chamber), which is the same principle as when the mixed gas flows from the diffusion chamber into the diffusion chamber. At this time, the residual accumulated water droplets can be further broken up and mixed with the gas, further avoiding the aggregation of liquid water.

[0025] Furthermore, the angle between the slope and the diffusion chamber is 20-45°.

[0026] The beneficial effects of this scheme are as follows: this scheme can avoid the situation where the slope is too large, resulting in the horizontal component velocity being too low when the gathered water droplets leave the slope, causing the flow rate to be too low, and at the same time, the negative "throttling" effect on the flow channel is obvious, increasing the back pressure at the pipeline outlet, thereby reducing the injection flow rate and the injection ratio; at the same time, it can avoid the situation where the slope is too small, resulting in the vertical component velocity being too low when the gathered water droplets leave the slope, and failing to generate sufficient upward velocity, failing to fully mix with the gas and falling and gathering again.

[0027] Furthermore, the angle between the slope and the diffusion chamber is 30°.

[0028] The beneficial effect of this solution is that the mixing effect of the water droplets and the mixed gas in this solution is better.

[0029] Furthermore, the height of the surface where the right-angle side of the spoiler ring and the diffusion chamber are perpendicular is 0.5 to 2 mm.

[0030] The beneficial effect of this solution is that the mixing effect of the water droplets and the mixed gas in this solution is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the liquid water distribution in the flow channel at the rear section of the ejector;

[0032] Figure 2 A three-dimensional diagram of an embodiment of the present invention;

[0033] Figure 3 for Figure 2 A cross-sectional view of

[0034] Figure 4 for Figure 3 Left view of the middle spoiler ring;

[0035] Figure 5 for Figure 3 A magnified view of the spoiler ring in ;

[0036] Figure 6 Schematic diagram of the positions of α and h in the present invention;

[0037] Figure 7 It is a numerical simulation velocity cloud diagram of the example shown in the embodiment of the present invention;

[0038] Figure 8 It is a numerical simulation flow field cloud diagram of the example shown in the embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following is further described in detail through specific implementation methods:

[0040] The figure marks in the drawings of the specification include: working fluid air inlet connector 1, nozzle 2, valve body 3, receiving chamber 301, mixing chamber 302, pressure diffusion chamber 303, diffusion chamber 304, spoiler ring 4, air outlet connector 5, and air inlet connector 6.

[0041] Example

[0042] The embodiment is basically as follows Figure 2 and Figure 3As shown, a fuel cell hydrogen injection mixer comprises a working fluid intake joint 1, a nozzle 2 and a valve body 3 which are connected in sequence from left to right. The nozzle 2 is installed at the left end of the valve body 3 by bolts. A receiving chamber 301, a mixing chamber 302, a pressure diffusion chamber 303 and a diffusion chamber 304 are coaxially arranged in the valve body 3 from left to right. The nozzle 2 is connected to the receiving chamber 301. The side wall of the receiving chamber 301 is provided with an injection air inlet, and the injection air inlet is connected to the injection air inlet joint 6. Specifically, the connection mode between the working fluid intake joint 1 and the nozzle 2 and the connection mode between the injection air inlet joint 6 and the receiving chamber 301 are the same as those in the prior art, and will not be repeated in this embodiment.

[0043] The diameter of the right end of the receiving chamber 301 is smaller than that of the left end. The diffusion chamber 303 is in the shape of a truncated cone with a diameter at the right end larger than that at the left end. The cross-section of the diffusion chamber 304 is circular, and the diameter of the diffusion chamber 304 is larger than the diameter of the right end of the diffusion chamber 303, so that a step is formed between the diffusion chamber 304 and the diffusion chamber 303.

[0044] The right end of the diffusion chamber 304 is connected to an outlet connector 5. The diameter of the inner cavity at the left end of the outlet connector 5 is equal to the diameter of the diffusion chamber 304. A spoiler ring 4 is pressed on the bottom of the diffusion chamber 304. Please refer to Figure 4 As shown, the central angle of the spoiler ring 4 in this embodiment is 180°, that is, the spoiler ring 4 is a semicircular ring, and the spoiler ring 4 is located at the rear of the diffusion chamber 304. A notch is provided on the top of the spoiler ring 4, that is, the radial cross section of the spoiler ring 4 in this embodiment is C-shaped. Figure 5 As shown, the cross-section of the spoiler ring 4 along the axial direction is a right triangle: one right-angled side is in contact with the side wall of the diffusion chamber 304, and the other right-angled side is perpendicular to the side wall of the diffusion chamber 304, and the right side of the right-angled side forms a flow channel with a sudden change in diameter; the hypotenuse faces the step, forming a slope with the right end higher than the left end.

[0045] Please refer to Figure 6 As shown, the angle between the hypotenuse and the side wall of the diffusion chamber 304 is set to α, and the height of the side wall opposite to α is set to h. In this embodiment, 20°≤α≤45° and 0.5mm≤h≤2mm are satisfied. Specifically, α is 30° and h is 2mm in this embodiment.

[0046] The specific implementation process is as follows:

[0047] In this embodiment, the new hydrogen enters the nozzle 2 from the working fluid inlet joint 1, and the high-temperature and high-humidity ejection gas is sucked into the receiving chamber 301 through the inlet joint 6 under the action of the Bernoulli principle, and while flowing to the right along the receiving chamber 301 and the mixing chamber 302, the low-temperature new hydrogen is mixed with the high-temperature and high-humidity ejection gas to form a mixed gas. In this process, the water vapor in the ejection gas is liquefied, and after entering the expansion chamber 303 and the diffusion chamber 304, it gathers into water droplets. When the mixed gas passes through the step position, the water droplets fall at the same time and converge at the lower part of the diffusion chamber 304. When the mixed gas and the water droplets pass through the spoiler ring 4, part of the water droplets are dispersed and "thrown" upward to form small water droplets with smaller particle size under the action of the spoiler ring 4, and the small water droplets are mixed with the mixed gas; at the same time, the spoiler ring 4 and the vertical side wall of the diffusion chamber 304 form a flow channel with a sudden change in diameter, and part of the water droplets are further broken up into small water droplets with smaller particle size and mixed with the mixed gas.

[0048] According to the above, numerical simulation is carried out on the preferred case, and the results are as follows Figure 7 and Figure 8 As shown, it can be seen that through the design of the diffusion chamber 304 and the spoiler ring 4, the gas at the ejector outlet is sufficiently disturbed, and the water clusters gathered at the bottom can also be smoothly sprinkled and fully mixed with the gas.

[0049] Finally, the mixed gas mixed with tiny water droplets directly enters the battery stack through the gas outlet connector 5. In this solution, since the liquid water is broken up into tiny water droplets, the small water droplets can flow along the battery stack along with the mixed gas, so the liquid water is dispersed in multiple cells of the battery stack, and will not gather in the first and second cells of the battery stack. After the liquid water is dispersed, there is less liquid water in each cell, and no flooding will occur.

[0050] Since the small water droplets are evenly distributed in all the batteries, the amount of liquid water in each battery is basically the same. After the battery stack has been working for a long time, the accumulated water can be discharged uniformly through the existing battery stack anode outlet. And because the liquid water will not gather in the first and second batteries, the water in the first and second batteries has enough time to flow to the anode outlet for unified discharge.

[0051] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A fuel cell hydrogen injection mixer, comprising a nozzle and a valve body, wherein a receiving chamber, a mixing chamber and a diffusion chamber are sequentially arranged in the valve body along the axial direction, the nozzle is connected to the receiving chamber, and an injection air inlet is arranged on the side wall of the receiving chamber, characterized in that: A diffusion chamber is provided on the side of the diffusion chamber away from the mixing chamber, and the bottom of the diffusion chamber is lower than the bottom of the end of the diffusion chamber away from the mixing chamber; a spoiler ring is provided in the diffusion chamber, and the spoiler ring is located at the lower part of the diffusion chamber.

2. A fuel cell hydrogen injection mixer according to claim 1, characterized in that: The cross sections of the diffusion chamber and the pressure diffuser chamber are both circular, and the diffusion chamber is coaxial with the pressure diffuser chamber. The diameter of the diffusion chamber is larger than the diameter of the pressure diffuser chamber at one end away from the mixing chamber.

3. A fuel cell hydrogen injection mixer according to claim 1, characterized in that: The spoiler ring is in a circular ring shape, and a notch is arranged on the upper part of the spoiler ring.

4. A fuel cell hydrogen injection mixer according to claim 3, characterized in that: The central angle corresponding to the spoiler ring is 180°.

5. A fuel cell hydrogen injection mixer according to claim 3 or 4, characterized in that: A slope is arranged on the side wall of the spoiler ring facing the pressure diffuser chamber, and the slope is an inclined surface which is inclined from one end away from the pressure diffuser chamber to a point close to the center of the spoiler ring.

6. A fuel cell hydrogen injection mixer according to claim 4, characterized in that: The cross section of the spoiler ring along the axial direction is a right triangle, the surface where the hypotenuse of the spoiler ring is located is a slope, and the surface where one right-angled side of the spoiler ring is located is in contact with the diffusion chamber.

7. A fuel cell hydrogen injection mixer according to claim 6, characterized in that: The angle between the slope and the diffusion chamber is 20 to 45 degrees.

8. A fuel cell hydrogen injection mixer according to claim 7, characterized in that: The angle between the slope and the diffusion chamber is 30°.

9. A fuel cell hydrogen injection mixer according to claim 7 or 8, characterized in that: The height of the surface where the right-angle side of the spoiler ring and the diffusion chamber are perpendicular is 0.5 to 2 mm.

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