A twisted tube fuel cell membrane humidifier and its use

Abstract

The application belongs to the technical field of proton exchange membrane fuel cells, and particularly relates to a twisted tube type fuel cell membrane humidifier and application thereof, which comprises a spiral twisted tube bundle, a humidified gas inlet and a humidified gas outlet respectively in communication with two ends of the spiral twisted tube bundle, and a hot and humid gas cavity in communication with the outer wall of the spiral twisted tube bundle; the hot and humid gas cavity is provided with a hot and humid gas inlet and outlet; the spiral twisted tube bundle comprises a plurality of spiral twisted tubes, any cross section of each spiral twisted tube is elliptical, the center of each cross section is located on the same axis, and the position of the major axis and the minor axis of the elliptical shape is periodically changed along the circumferential direction of the spiral twisted tube. The twisted tube type fuel cell membrane humidifier can enhance the heat and mass transfer process in the humidifier, improve the humidification efficiency, reduce the resistance coefficient in the gas flow channel, and make the equipment structure more compact.

Description

Technical Field

[0001] This invention belongs to the field of proton exchange membrane fuel cell technology, specifically relating to a twisted tube type fuel cell membrane humidifier and its application. Background Technology

[0002] Fuel cells directly convert the chemical energy stored in fuel into electrical energy, offering advantages such as high efficiency and cleanliness. Proton exchange membrane fuel cells (PEMFCs) are a type of fuel cell that uses a polymer membrane. They possess advantages such as low operating temperature, high energy density, and fast start-up speed, and are currently widely used. The polymer membrane in a PEMFC transports protons and water molecules while isolating gases; it only becomes a good proton conductor when fully hydrated. Research shows that if the water content of the polymer membrane is too low, it leads to a decrease in membrane proton conductivity and the rate of the cell's electrochemical reaction. To ensure the polymer membrane remains humid, adequately humidifying the reactant gases entering the fuel cell is a widely adopted technique.

[0003] Tubular membrane humidifiers are a common humidification technology that utilizes the hot, humid exhaust gas from fuel cells to humidify the reaction gases. Hollow fiber bundles are the key components of tubular membrane humidifiers. The gas to be humidified and the hot, humid exhaust gas flow inside and outside the fiber bundles, respectively. Heat and moisture diffuse from the outside to the inside of the fiber bundles through the fiber walls, achieving the heating and humidification process for the reaction gases. Compared to other membrane humidifiers, tubular membrane humidifiers have a larger heat and mass transfer area, higher humidification efficiency, and are also lighter in weight. However, currently, the hollow fiber bundles in tubular membrane humidifiers are all straight tubes. As the fuel cell power increases and the gas flow rate in the membrane humidifier increases, the friction loss inevitably increases, leading to a decrease in the humidification efficiency of the membrane humidifier. Therefore, it is necessary to provide an improved twisted tubular fuel cell membrane humidifier to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a twisted tubular fuel cell membrane humidifier and its application, so as to enhance the heat and mass transfer effect and improve the heating and humidification efficiency.

[0005] To achieve the above objectives, the present invention provides a twisted tube fuel cell membrane humidifier, comprising a helical twisted tube bundle, a gas inlet to be humidified and a humidified gas outlet respectively connected to both ends of the helical twisted tube bundle, and a hot and humid gas cavity communicating with the outer wall of the helical twisted tube bundle; the hot and humid gas cavity is provided with a hot and humid gas inlet and an outlet.

[0006] The spiral twisted tube bundle includes several spiral twisted tubes, each of which has an elliptical cross-section at any point, and the center of each cross-section is located on the same axis. The positions of the major axis and minor axis of the ellipse rotate periodically along the circumference of the spiral twisted tube.

[0007] Furthermore, the torque S of the spiral twisted tube is 9-11 mm, and the ratio of its major axis to its minor axis is 1.4-1.6.

[0008] Furthermore, the major axis of the spiral twisted tube is 1-1.4 mm, the minor axis is 0.6-0.9 mm, and the wall thickness is 0.08-0.12 mm.

[0009] Furthermore, the hot and humid gas cavity is a tubular shell, and the spiral twisted tube bundle is disposed inside the tubular shell; the two ends of the tubular shell are respectively provided with a front gasket and a rear gasket, and the front gasket and the rear gasket are provided with through holes that cooperate with each of the spiral twisted tubes for connecting with the spiral twisted tubes.

[0010] Furthermore, the front gasket and the rear gasket are connected to the front cover and the rear cover respectively. The front cover is provided with the inlet of the gas to be humidified, and the rear cover is provided with the outlet of the humidified gas (9).

[0011] Furthermore, the tubular shell has a hot and humid gas inlet and a hot and humid gas outlet on its two end peripheral walls, respectively, with the hot and humid gas inlet located near the outlet of the humidified gas and the hot and humid gas outlet located near the inlet of the gas to be humidified.

[0012] Furthermore, the hot and humid gas inlet is connected to the exhaust gas outlet of the fuel cell, and is used to introduce the high-heat and high-humidity exhaust gas generated by the fuel cell.

[0013] Furthermore, the outer spiral lines of each of the spiral twisted tubes are in contact with each other, and the twisting direction of each of the spiral twisted tubes is the same.

[0014] Furthermore, the material of the spiral twisted tube bundle is polyethersulfone.

[0015] The present invention also provides an application of the twisted tube type fuel cell membrane humidifier described in any one of the above claims in a large-scale proton exchange membrane fuel cell testing system.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0017] (1) This invention twists the traditional circular hollow fiber tube into an elliptical coaxial spiral twisted tube. When the gas flows inside the twisted tube, the flow direction continuously rotates and changes along the tube's axis, increasing the turbulence intensity. Simultaneously, the rotating flow of the fluid inside the tube also generates a secondary swirling flow perpendicular to the mainstream direction. This secondary swirling flow thins the thermal boundary layer at the wall surface, thus enhancing the heat transfer performance of the twisted tube. After adopting the spiral twisted tube in the hollow fiber tube of the membrane humidifier, the degree of gas disturbance outside the tube is enhanced. Near the tube wall, the airflow generates radial velocity, and the flow rate further increases, which helps the high-concentration water vapor outside the tube to diffuse across the twisted tube wall into the tube. Therefore, the water vapor transfer rate of the spiral twisted tube is improved.

[0018] (2) In this invention, the fiber tubes are spiral twisted tubes, with the spiral lines on the outer edges of the twisted tubes contacting each other, reducing the spacing between tubes and making the tube bundle structure more compact. At the same time, each twisted tube supports each other, which can effectively reduce the vibration generated when the gas flows through, and improve the operational reliability of the membrane humidifier.

[0019] (3) Because the structure of the present invention is more compact and has higher humidification efficiency under the same gas flow rate, the overall structural size is reduced, the weight of the device is reduced, and the production cost is reduced. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the twisted tube membrane humidifier provided in this invention example;

[0021] Figure 2 This is a longitudinal cross-sectional view along the axis of the twisted tubular membrane humidifier provided in this invention example;

[0022] Figure 3 This is a schematic diagram of the front and rear gasket structure provided in an example of the present invention;

[0023] Figure 4 This is a front cross-sectional view of the spiral twisted tube provided in this invention example;

[0024] Figure 5 This is a three-dimensional structural schematic diagram of the spiral twisted tube provided in this invention example;

[0025] Figure 6 This is a left view of the spiral twisted tube provided in an example of the present invention;

[0026] Figure 7 This is a schematic diagram of the overall structure of the spiral twisted tube bundle provided in this invention.

[0027] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0028] 1-Inlet for humidified gas; 2-Front end cover; 3-Front gasket; 4-Hot and humid gas outlet; 5-Tube shell; 6-Hot and humid gas inlet; 7-Rear gasket; 8-Rear end cover; 9-Hydrated gas outlet; 10-Helical twisted tube bundle; 11-Inlet chamber; 12-Hot and humid gas chamber; 13-Outlet chamber; 14-Flow channel for humidified gas. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Please see Figure 1-7 The present invention provides a twisted tube type fuel cell membrane humidifier, including a spiral twisted tube bundle 10, a gas inlet 1 to be humidified and a humidified gas outlet 9 respectively connected to both ends of the spiral twisted tube bundle 10, and a hot and humid gas cavity 12 connected to the outer wall of the spiral twisted tube bundle 10; the hot and humid gas cavity 12 is provided with a hot and humid gas inlet and an outlet.

[0031] The spiral twisted tube bundle 10 includes a plurality of spiral twisted tubes, each of which has an elliptical cross-section at any point, and the center of each cross-section is located on the same axis. The positions of the major axis and minor axis of the ellipse rotate periodically along the circumference of the spiral twisted tube.

[0032] In this configuration, the gas to be humidified flows through the inside of the spiral twisted tube bundle 10, while the hot, humid gas flows through the outside of the hot, humid gas chamber 12, i.e., the spiral twisted tube bundle 10. Because the spiral twisted tube bundle 10 has good thermal conductivity and allows water molecules to pass through while preventing gas from passing through, the heat and moisture of the hot, humid gas are transferred to the gas to be humidified inside the spiral twisted tube bundle 10, thus heating and humidifying it. The spiral twisted tubes are hollow fiber tubes, arranged in the same direction to form the fiber bundle within the membrane humidifier shell. Compared to traditional straight-tube membrane humidifiers, this twisted tube configuration results in a more compact fiber bundle arrangement, a smaller cross-sectional area, and a constant flow wetted perimeter. The flow direction of the gas to be humidified within the twisted tube changes continuously along the axial direction. Therefore, while reducing the weight of the humidifier, it further enhances heat and mass transfer effects and improves heating and humidification efficiency.

[0033] Please see Figure 4-6The major axis, minor axis, and torque of the spiral twisted tube can be varied according to the gas flow rate of the membrane humidifier. The number of spiral twisted tubes can also be adjusted according to the gas flow rate of the membrane humidifier. In some specific embodiments, the torque S of the spiral twisted tube is 9-11 mm (torque refers to the length of the twisted tube between the initial point and the point after rotation when a point on the outside of the twisted tube wall returns to the same position after periodic rotation, and the line connecting the initial point and the point after rotation is parallel to the axis of the spiral twisted tube), preferably 10 mm, and the ratio of the major axis to the minor axis is 1.4-1.6, preferably 1.5. The length of the major axis of the spiral twisted tube is 1-1.4 mm, preferably 1.2 mm, the length of the minor axis is 0.6-0.9 mm, preferably 0.8 mm, and the wall thickness of the spiral twisted tube is 0.08-0.12 mm, preferably 0.1 mm. With these preferred torque and major axis-to-minor axis ratios, the spiral twisted tube has better humidification efficiency.

[0034] Please see Figure 7 Specifically, the outer spiral lines of each of the spiral twisted tubes are in contact with each other, and the spiral twisted tubes support each other. The twisting direction of each spiral twisted tube is the same, meaning all the twisted tubes are arranged in the same direction. The spiral twisted tube bundle is made of polyethersulfone material, such as a sulfonated polyethersulfone proton exchange membrane. Because the major and minor axes of the elliptical cross-section of the spiral twisted tubes rotate periodically in a spiral pattern, numerous pores are formed between the spiral twisted tubes to allow hot and humid gas to pass through, thus facilitating heat and moisture exchange with the internal gas to be humidified. When the gas flows inside the twisted tube, the flow direction continuously rotates and changes along the tube's axial direction, increasing turbulence intensity. Simultaneously, the rotating flow of the fluid inside the tube also generates a secondary vortex perpendicular to the main flow direction. This secondary vortex thins the thermal boundary layer at the wall, thus enhancing the heat transfer performance of the twisted tube. At the same time, the external hot and humid gas also experiences flow impact under the rotational twisting of the outer wall of the twisted tube, which is more conducive to the permeation of water molecules, thereby improving the humidification efficiency.

[0035] Please see Figure 1 and 2 The hot and humid gas chamber 12 is formed by a tubular shell 5, and the spiral twisted tube bundle 10 is installed inside the tubular shell 5. A front gasket 3 and a rear gasket 7 are respectively provided at both ends of the tubular shell 5. The front gasket 3 and the rear gasket 7 have through holes that mate with each of the spiral twisted tubes for connection. In this configuration, the front gasket 3 and the rear gasket 7 seal both ends of the tubular shell 5, forming the hot and humid gas chamber 12. The through holes of the front gasket 3 and the rear gasket 7 only communicate with the spiral twisted tubes, so the hot and humid gas will not escape from the front gasket 3 and the rear gasket 7. The gas to be humidified flows from the outside of the front gasket 3 into the spiral twisted tube through the through hole, and then flows out from the through hole of the rear gasket 7.

[0036] The spiral twisted tube bundle 10 of the membrane humidifier is fitted with a front sealing colloid between itself and the front gasket 2, and a rear sealing colloid between itself and the rear gasket 7. The sealing colloid is used to seal the gap between the tube bundle and the gasket to prevent the gases in the air inlet, air outlet and exhaust chambers from interpenetrating and mixing, thereby reducing the humidification efficiency.

[0037] The number of holes for the front gasket 3 and the rear gasket 7 to mate with the spiral twisted tube bundle 10 is determined according to the number of twisted tubes. In this example, the front and rear end caps, the front and rear gaskets, and the shell cross-section are all circular, but their shapes can also be other structures.

[0038] Specifically, the front gasket 3 and the rear gasket 7 are connected to the front cover 2 and the rear cover 8, respectively. The front cover 2 is provided with the inlet 1 for the gas to be humidified, and the rear cover 8 is provided with the outlet 9 for the humidified gas. The cavity formed between the front cover 2 and the front gasket 3 is the inlet cavity 11 for the gas to be humidified, and the cavity formed between the rear cover 8 and the rear gasket 7 is the outlet cavity 13 for the humidified gas. After the gas to be humidified enters the humidifier through the inlet of the front cover 2, it flows evenly into each twisted tube through the inlet cavity 11.

[0039] The tubular shell 5 has a hot and humid gas inlet 6 and a hot and humid gas outlet 4 respectively on its two end peripheral walls. Preferably, the hot and humid gas inlet 6 is located near the humidified gas outlet 9, and the hot and humid gas outlet 4 is located near the gas inlet 1 to be humidified. With this arrangement, the gas to be humidified inside the spiral twisted tube flows in the opposite direction to the hot and humid waste gas outside the tube, maximizing the heat and mass transfer efficiency inside and outside the twisted tube.

[0040] Specifically, the hot and humid gas inlet 6 is connected to the exhaust gas outlet of the fuel cell and is used to introduce the high-heat, high-humidity exhaust gas generated by the fuel cell. After entering the humidifier through the hot and humid gas inlet 6 at the bottom of the humidifier housing, the fuel cell exhaust gas flows out through the exhaust gas chamber (hot and humid gas chamber 12) and exits from the exhaust gas outlet (hot and humid gas outlet 4) at the top of the humidifier. The heat and moisture in the exhaust gas are transferred to the gas to be humidified inside the twisted tube wall.

[0041] In some specific implementations, such as Figure 4-6 As shown, the torque S of the spiral twisted tube is 10 mm. Meanwhile, as... Figure 7 The outer spiral edges of adjacent twisted tubes contact each other, and the twisted tubes support each other, all arranged in the same direction. The length and number of twisted tubes can be determined based on the specific flow rate of the membrane humidifier. For example... Figure 6As shown, the cross-section of the spiral twisted tube is elliptical. The major semi-axis a of the twisted tube is 0.6 mm, the minor semi-axis b is 0.4 mm, and the membrane thickness (tube wall thickness) t is 0.1 mm. A higher degree of twist in the hollow fiber tube results in a greater water vapor transfer rate, but this comes at the cost of increased resistance to gas flow outside the tube and higher pumping power. Considering both the water vapor transfer rate and gas pumping power of the membrane humidifier, this invention designs the spiral twisted tube with a torque S of 10 mm, major and minor axis lengths of 1.2 mm and 0.8 mm respectively, and a major-to-minor axis ratio of 1.5. Under these structural parameters, the membrane humidifier exhibits the highest humidification efficiency.

[0042] In this embodiment, the humidified gas inlet 1 is connected to an air compressor or a hydrogen storage tank. After the humidified gas enters the inlet chamber 11, it flows evenly into the gas channel 14 in the spiral twisted tube. After being heated and humidified, it is collected in the outlet chamber 13 and flows out of the membrane humidifier through the gas outlet 9. The gas outlet 9 is connected to the inlet of the fuel cell. After the reaction gas is humidified, it directly supplies gas to the fuel cell.

[0043] In this embodiment, the fuel cell exhaust gas inlet (hot and humid gas inlet 6) is connected to the fuel cell exhaust gas outlet. The hot and humid exhaust gas generated by the fuel cell is introduced into the membrane humidifier, passes through the fuel cell exhaust gas chamber, and undergoes sufficient heat and mass exchange with the gas to be humidified inside the spiral twisted tube wall. Finally, it flows out of the membrane humidifier from the hot and humid gas outlet 4.

[0044] The working process of the twisted tube membrane humidifier provided in this embodiment is described in detail below: This twisted tube membrane humidifier is suitable for proton exchange membrane fuel cells. During operation, the membrane humidifier is first preheated. The exhaust gas outlet of the fuel cell is connected to the exhaust gas inlet (hot and humid gas inlet 6) at the bottom of the casing. The hot and humid exhaust gas generated by the fuel cell enters the exhaust gas chamber (hot and humid gas chamber 12) of the membrane humidifier, preheating the spiral twisted tube bundle 10 inside the casing. After preheating, the reaction gas required by the fuel cell is humidified. The inlet 1 of the gas to be humidified is connected to an air compressor or a hydrogen storage tank. After the gas to be humidified enters the inlet chamber 11, it passes through the front gasket 3 and evenly enters the gas flow channel 14 of the spiral twisted tube. Driven by temperature and water concentration differences, it exchanges heat and moisture with the hot and humid exhaust gas in the exhaust gas chamber. The heat and moisture in the exhaust gas are transferred to the inside of the tube through the twisted tube wall, thus humidifying the gas inside the tube. After sufficient heat and moisture exchange, the exhaust gas in the exhaust chamber is discharged from the exhaust gas outlet (hot and humid gas outlet 4) at the top of the humidifier, while the humidified gas inside the pipe is collected by the rear gasket 7 and enters the exhaust chamber 13, and is discharged from the humidifier from the gas outlet 9 on the rear cover 8. The gas outlet 9 is connected to the air inlet of the fuel cell, and the gas humidified by the membrane humidifier will be used as the reaction gas of the fuel cell.

[0045] In summary, the twisted tube membrane humidifier of the present invention can enhance the heat transfer process of the twisted tube, reduce the mass transfer resistance, improve the humidification efficiency of the humidifier, and the structure of the spiral twisted tube bundle is more compact, which can reduce the weight of the device and reduce the production cost.

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A twisted tube type fuel cell membrane humidifier, characterized in that, It includes a spiral twisted tube bundle (10), a humidified gas inlet (1) and a humidified gas outlet (9) respectively connected to both ends of the spiral twisted tube bundle (10), and a hot and humid gas cavity (12) connected to the outer wall of the spiral twisted tube bundle (10); the hot and humid gas cavity (12) is provided with a hot and humid gas inlet and an outlet; The hot and humid gas cavity (12) is a tubular shell (5), and the spiral twisted tube bundle (10) is disposed inside the tubular shell (5); the two ends of the tubular shell (5) are respectively provided with a front gasket (3) and a rear gasket (7), and the front gasket (3) and the rear gasket (7) are provided with through holes that cooperate with each of the spiral twisted tubes for connecting with the spiral twisted tubes; The spiral twisted tube bundle (10) includes a plurality of spiral twisted tubes, each of which has an elliptical cross-section at any point, and the center of each cross-section is located on the same axis. The positions of the major axis and minor axis of the ellipse rotate periodically along the circumference of the spiral twisted tube. The torque S of the spiral twisted tube is 9~11mm; The long axis of the spiral twisted tube is 1.2 mm, the short axis is 0.8 mm, and the wall thickness of the spiral twisted tube is 0.1 mm. The material of the spiral twisted tube bundle is sulfonated polyethersulfone proton exchange membrane. The heat and moisture of the hot and humid gas are transferred to the gas to be humidified in the spiral twisted tube bundle (10) to heat and humidify it. The tubular shell (5) has a hot and humid gas inlet (6) and a hot and humid gas outlet (4) on its two ends respectively. The hot and humid gas inlet (6) is located near the humidified gas outlet (9), and the hot and humid gas outlet (4) is located near the gas inlet (1) to be humidified. The hot and humid gas inlet (6) is connected to the exhaust gas outlet of the fuel cell and is used to introduce the hot and humid exhaust gas generated by the fuel cell.

2. The twisted tubular fuel cell membrane humidifier according to claim 1, characterized in that, The front gasket (3) and the rear gasket (7) are connected to the front cover (2) and the rear cover (8) respectively. The front cover (2) is provided with the humidified gas inlet (1), and the rear cover (8) is provided with the humidified gas outlet (9).

3. The twisted tubular fuel cell membrane humidifier according to claim 1, characterized in that, The outer spiral lines of each of the spiral twisted tubes are in contact with each other, and the twisting direction of each of the spiral twisted tubes is the same.

4. The application of the twisted tube type fuel cell membrane humidifier according to any one of claims 1-3 in a proton exchange membrane fuel cell testing system.

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