Heat exchanger, solid oxide fuel cell and air preheating method

Abstract

The invention provides a heat exchanger, a solid oxide fuel cell and an air preheating method, and belongs to the field of solid oxide fuel cells. Comprising an air guide cavity, a heat exchange unit and a cold stream air outlet pipe, and the air guide cavity comprises a cold stream air inlet cavity and a hot stream air outlet cavity. The heat exchange unit is arranged in the inner shell cavity and comprises a first cold flow cavity and a second cold flow cavity which are arranged in parallel in a spaced mode and connected with each other. In the interval direction, the outer contour of the second cold flow cavity is smaller than that of the first cold flow cavity, the multiple heat exchange units are sequentially stacked and connected, the first cold flow cavity located on one side is connected with an outlet of the cold flow stream air inlet cavity, a hot flow stream flowing hole is formed in the middle of the first cold flow cavity, and the second cold flow cavity located on the other side communicates with the cold flow stream air outlet pipe. The other end of the cold stream air outlet pipe is arranged outside the air guide cavity in a penetrating mode and provided with a cold stream air outlet hole. By the adoption of the heat exchanger, miniaturization and light weight of the heat exchanger and the whole solid oxide fuel cell can be achieved, and integration and adaptability are improved.

Description

Technical Field

[0001] The invention relates to the field of solid oxide fuel cells, and in particular to a heat exchanger, a solid oxide fuel cell and an air preheating method. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) is a device that converts chemical energy in fuel directly into electrical energy. It has the advantages of strong fuel adaptability, high energy density, no pollution, and low noise. Its working principle is that air is input by a blower, enters the cathode of the fuel cell after heat exchange through a heat exchanger, and the fuel or other alkane gas in the gas cylinder is reformed into hydrogen and enters the anode. Electrochemical reactions are carried out inside the stack to generate electricity, and the remaining unreacted fuel enters the combustion chamber for combustion, and the waste heat generated is used to preheat the system intake. Among them, the heat exchanger is one of the important components of the system.

[0003] In the related technology, the existing solid oxide fuel cell system usually adopts a fin-type heat exchanger, which is formed by stacking and welding multiple layers of fins. Each layer of fins is processed with different flow channel structures. When working, air and heat source flow gas are respectively introduced into the spaced flow channels. The heat of the heat source flow gas is transferred to the air side through the half fin plate, and the system intake air is preheated by contact heat exchange.

[0004] However, in order to ensure sufficient heat exchange area, the heat exchanger form used in the related art needs to have a multi-layer fin structure to form staggered cold and hot flow channels, and the fins need to be sealed and connected by high-temperature brazing. The processing steps are complicated, and the overall structure occupies a large space and weight, which makes it difficult to meet the needs of miniaturization and lightweight of solid oxide fuel cell systems, resulting in limited application scenarios and poor adaptability. Summary of the invention

[0005] The embodiments of the present invention provide a heat exchanger, a solid oxide fuel cell and an air preheating method, which can achieve miniaturization and lightness of the heat exchanger and the entire solid oxide fuel cell on the basis of meeting the requirements of heat exchange efficiency, and improve integration and adaptability. The technical solution is as follows:

[0006] In a first aspect, an embodiment of the present invention provides a heat exchanger, which is arranged in an inner shell chamber of a solid oxide fuel cell system, wherein a hot stream inlet is arranged on a cavity wall of the inner shell chamber, and comprises: an air guide cavity, a heat exchange unit and a cold stream outlet pipe,

[0007] The air guide cavity comprises a cold flow inlet cavity and a hot flow outlet cavity which are isolated from each other;

[0008] The heat exchange unit is arranged in the inner shell chamber, including a first cold flow chamber and a second cold flow chamber in the shape of a plate, the first cold flow chamber and the second cold flow chamber are arranged in parallel and spaced apart, and are connected by a cold flow interface arranged on adjacent side walls, in the spacing direction, the outer contour of the second cold flow chamber is smaller than the outer contour of the first cold flow chamber, the heat exchange unit is stacked in sequence and arranged in sequence through the cold flow interface, the first cold flow chamber on one side in the stacking direction is connected to the outlet of the cold flow inlet chamber, and a hot flow flow hole communicating with the hot flow outlet chamber is arranged in the middle, the second cold flow chamber on the other side in the stacking direction is communicated with one end of the cold flow outlet pipe, the other end of the cold flow outlet pipe is penetrated outside the air guide chamber, and a cold flow outlet hole is arranged on the side wall.

[0009] Optionally, the hot flow stream flow hole is provided in the middle of the first cold flow cavity in a plurality of the heat exchange units.

[0010] Optionally, the outer contour of the first cold flow cavity is a square, and the outer contour of the second cold flow cavity is a regular polygon.

[0011] Optionally, in the stacking direction, the cold flow interfaces on both sides of the second cold flow cavity are arranged symmetrically with respect to the outer contour center of the second cold flow cavity.

[0012] Optionally, arc chamfers are provided at the corners of the outer contour edges of the first cold flow cavity and the second cold flow cavity.

[0013] Optionally, the cold flow outlet holes are provided in multiple groups, each group includes a plurality of the cold flow outlet holes arranged at equal angles around the circumference of the cold flow outlet pipe, and the multiple groups of cold flow outlet holes are evenly spaced along the extension direction of the cold flow outlet pipe.

[0014] Optionally, a temperature sensor interface is provided on the cold flow outlet pipe.

[0015] Optionally, the air guide cavity, the first cold flow cavity, the second cold flow cavity and the cold flow outlet pipe are all stainless steel structural parts.

[0016] In a second aspect, an embodiment of the present invention provides a solid oxide fuel cell, comprising the heat exchanger described in the first aspect.

[0017] In a third aspect, an embodiment of the present invention provides an air preheating method, which is implemented based on the heat exchanger described in the first aspect, and the method includes:

[0018] Based on the specifications of the solid oxide fuel cell, an appropriate number of groups of the heat exchange units are selected to be combined with the air guide cavity and the cold flow outlet pipe to be connected and arranged inside the solid oxide fuel cell;

[0019] The heat source flow gas is introduced through the hot flow stream inlet on the inner shell chamber, and the heat source flow gas flows through the flow channel space formed by the inner side wall of the inner shell chamber and the outer surfaces of the first cold flow cavity and the second cold flow cavity, and finally flows out from the hot flow stream outlet cavity to form a hot side circulation;

[0020] Low-temperature air is introduced from the blower side through the cold flow inlet cavity, and the low-temperature air flows through the first cold flow cavity and the second cold flow cavity and exchanges heat with the heat source flow gas to achieve preheating, and finally enters the cathode of the solid oxide fuel cell through the cold flow outlet hole on the cold flow outlet pipe to perform electrochemical reaction.

[0021] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0022] The heat exchanger structure provided in the embodiment of the present invention is used to preheat the air entering the solid oxide fuel cell. Compared with the traditional heat exchanger form that uses fin plates to stack to form hot flow streams and cold flow streams, the inner shell chamber in the solid oxide fuel cell system is directly used as part of the hot side circulation. The plate-shaped first cold flow chamber and the second cold flow chamber are set in the inner shell chamber by axial stacking as the cold flow stream flow channels for introducing air, and the outer contours of the two are distinguished to ensure that the heat source flow gas and air in the hot side circulation can achieve sufficient heat exchange. Through assembly and matching with the inner shell of the system, the heat exchange unit can be increased or decreased according to the size specifications of the inner shell chamber and the actual heat exchange requirements, and it is docked and welded and fixed by the cold flow interface, which is also simpler and more convenient than the sealing welding between traditional fin plates. It can achieve miniaturization and lightweight of the heat exchanger and the entire solid oxide fuel cell on the basis of meeting the requirements of heat exchange efficiency, and improve integration and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 is a schematic diagram of the three-dimensional structure of one side of a heat exchanger provided by an embodiment of the present invention;

[0025] Figure 2 is a partial structural cross-sectional view of the other side of the heat exchanger provided by an embodiment of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the heat exchanger and the inner shell chamber provided by an embodiment of the present invention;

[0027] Figure 4 is a schematic structural diagram of one side of the first cold flow cavity provided by an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of the three-dimensional structure of the other side of the first cold flow cavity provided by an embodiment of the present invention;

[0029] Figure 6 is a schematic diagram of the three-dimensional structure of one side of the second cold flow cavity provided by an embodiment of the present invention;

[0030] Figure 7 is a schematic diagram of the side structure of one side of the second cold flow cavity provided by an embodiment of the present invention;

[0031] Figure 8 is a schematic diagram of the side structure of the other side of the second cold flow cavity provided by an embodiment of the present invention;

[0032] Fig. 9 It is a flow chart of an air preheating method provided by an embodiment of the present invention.

[0033] In the figure: 1-air guide cavity; 2-heat exchange unit; 3-cold flow outlet pipe; 11-cold flow inlet cavity; 12-hot flow outlet cavity; 21-first cold flow cavity; 22-second cold flow cavity; 23-cold flow interface; 24-hot flow flow hole; 31-cold flow outlet hole; 32-temperature sensor interface; m-inner shell chamber; m1-hot flow inlet. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Figure 1 is a schematic diagram of the three-dimensional structure of one side of a heat exchanger provided by an embodiment of the present invention; Figure 2 is a partial structural cross-sectional view of the other side of the heat exchanger provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the heat exchanger and the inner shell chamber provided by an embodiment of the present invention; Figure 4 is a schematic structural diagram of one side of the first cold flow cavity provided by an embodiment of the present invention; Figure 5 is a schematic diagram of the three-dimensional structure of the other side of the first cold flow cavity provided by an embodiment of the present invention; Figure 6 is a schematic diagram of the three-dimensional structure of one side of the second cold flow cavity provided by an embodiment of the present invention; Figure 7 is a schematic diagram of the side structure of one side of the second cold flow cavity provided by an embodiment of the present invention; Figure 8 FIG. 2 is a schematic diagram of the side view of the second cold flow cavity on the other side provided by an embodiment of the present invention. Figures 1 to 8 As shown, the embodiment of the present invention first provides a heat exchanger, referring to Figures 1 to 6 , including an inner shell chamber m arranged in a solid oxide fuel cell system, a hot flow inlet m1 is arranged on the cavity wall of the inner shell chamber m, and is characterized in that it includes: an air guide cavity 1, a heat exchange unit 2 and a cold flow outlet pipe 3.

[0036] Among them, the air guide cavity 1 includes a cold flow inlet cavity 11 and a hot flow outlet cavity 12 isolated from each other. The heat exchange unit 2 is arranged in the inner shell chamber m, including a plate-shaped first cold flow cavity 21 and a second cold flow cavity 22, which are arranged in parallel and spaced apart, and connected by a cold flow interface 23 arranged on the adjacent side walls. In the spacing direction, the outer contour of the second cold flow cavity 22 is smaller than the outer contour of the first cold flow cavity 21. The heat exchange unit 2 is stacked in sequence and connected in sequence through the cold flow interface 23. The first cold flow cavity 21 located on one side in the stacking direction is connected to the outlet of the cold flow inlet cavity 11, and a hot flow flow hole 24 connected to the hot flow outlet cavity 12 is arranged in the middle, and the second cold flow cavity 22 located on the other side in the stacking direction is connected to one end of the cold flow outlet pipe 3. The other end of the cold flow outlet pipe 3 is arranged outside the air guide cavity 1, and a cold flow outlet hole 31 is arranged on the side wall.

[0037] In an embodiment of the present invention, the heat exchanger is adaptively configured based on the specifications of the Goodt oxide fuel cell, and is stacked by selecting an appropriate number of groups of heat exchange units 2. For example, in this embodiment, 5 groups of heat exchange units 2 are provided, and the stacking forms a form in which the first cold flow cavity 21, the second cold flow cavity 22, and the first cold flow cavity 21 are arranged in sequence. The side panels of the adjacent first cold flow cavity 21 and the second cold flow cavity 22 are close to each other, and the coaxially arranged cold flow interfaces 23 are provided. After alignment, the groups are welded and fixed by brazing and other means to achieve the connection between the groups. In the stacking direction, one side of the multiple groups of heat exchange units 2 is the first cold flow cavity 21, and the first cold flow cavity 21 is connected to the outlet of the cold flow inlet cavity 11 by using the cold flow interface 23 preset for docking with the second cold flow cavity 22, as the inlet end of the air to be preheated. A hot flow stream flow hole 24 is also provided in the middle of the first cold flow chamber 21, and the hot flow stream flow hole 24 is connected to the hot flow stream outlet chamber 12 to achieve the docking of the heat exchange unit 2 and the air guide chamber 1. In the stacking direction, the other side of the multiple groups of heat exchange units 2 is the second cold flow chamber 22, which is connected to the cold flow stream outlet pipe 3 extending along the stacking direction. The above structure is connected to one side of the inner shell chamber m through the air guide chamber 1, and the cold flow stream outlet hole 31 extends from the other side of the inner shell chamber m, and the end of the cold flow stream outlet hole 31 is used to extend into the cathode side of the solid oxide fuel cell stack.

[0038] When the solid oxide fuel cell is working, the heat source flow gas is introduced through the hot flow stream inlet m1 on the inner shell chamber m, such as the gas after the solid oxide fuel cell is burned by the burner or the unused fuel tail gas after passing through the solid oxide fuel cell. The above-mentioned heat source flow gas flows through the flow channel space formed by the inner side wall of the inner shell chamber m and the outer surface of the first cold flow cavity 21 and the second cold flow cavity 22, wherein, since the outer contour of the second cold flow cavity 22 is smaller than the outer contour of the first cold flow cavity 21 in the spacing direction, the above-mentioned heat source flow gas can fully flow into the gap between the first cold flow cavity 21 and the second cold flow cavity 22 to achieve full contact. The above-mentioned heat source flow gas finally enters the hot flow stream outlet cavity 12 through the hot flow stream flow hole 24 and is discharged from the inner shell chamber m to form a hot side circulation.

[0039] At the same time, low-temperature air is introduced from the blower side through the cold flow inlet chamber 11, and the low-temperature air flows through the first cold flow chamber 21 and the second cold flow chamber 22 and exchanges heat with the external heat source flow gas to achieve preheating, and finally enters the cathode of the solid oxide fuel cell through the cold flow outlet hole 31 on the cold flow outlet pipe 3 to carry out electrochemical reaction.

[0040] The heat exchanger structure provided in the embodiment of the present invention is used to preheat the air entering the solid oxide fuel cell. Compared with the traditional heat exchanger form that uses fin plates to stack to form hot flow streams and cold flow streams, the inner shell chamber m in the solid oxide fuel cell system is directly used as part of the hot side cycle. The plate-shaped first cold flow chamber 21 and the second cold flow chamber 22 are stacked axially in the inner shell chamber m as cold flow streams for introducing air, and the outer contours of the two are distinguished to ensure that the heat source flow gas and air in the hot side cycle can achieve sufficient heat exchange. Through assembly and matching with the inner shell of the system, the heat exchange unit 2 can be increased or decreased according to the size specifications of the inner shell chamber m and the actual heat exchange requirements, and it is docked and welded and fixed by the cold flow interface 23, which is simpler and more convenient than the sealing welding between traditional fin plates. It can achieve miniaturization and lightweight of the heat exchanger and the entire solid oxide fuel cell on the basis of meeting the requirements of heat exchange efficiency, and improve integration and adaptability.

[0041] Optionally, a hot flow stream flow hole 24 is provided in the middle of each of the first cold flow chambers 21 in the plurality of heat exchange units 2. Exemplarily, in the embodiment of the present invention, each of the first cold flow chambers 21 in the plurality of heat exchange units 2 adopts a uniform structural form in which a hot flow stream flow hole 24 is provided in the middle. On the basis of convenient unified production, in addition to the first cold flow chamber 21 located on one side in the stacking direction being connected to the air guide chamber 1 through the hot flow stream flow hole 24, the hot flow stream flow holes 24 in the middle of the remaining first cold flow chambers 21 can also be used as a channel for the hot source flow gas to shuttle between the plurality of heat exchange units 2, further increasing the heat exchange area and ensuring the heat exchange efficiency.

[0042] Optionally, the outer contour of the first cold flow cavity 21 is a square, and the outer contour of the second cold flow cavity 22 is a regular polygon. For example, in an embodiment of the present invention, the outer contour of the first cold flow cavity 21 is a square, and the outer contour of the second cold flow cavity 22 is a regular octagon. The above arrangement can ensure that the heat source flow gas can flow from the four corner notches of the second cold flow cavity 22 into the gap between the first cold flow cavity 21 and the second cold flow cavity 22 from four sides, thereby adjusting the gas flow rate and ensuring the uniformity and sufficiency of heat exchange. In other possible implementation methods, according to the different specifications and sizes of the inner shell chamber m of the small solid oxide fuel cell, structures with other numbers of sides such as regular hexagons and regular decagons can also be used, and the embodiments of the present invention are not limited here.

[0043] Optionally, in the stacking direction, the cold flow interfaces 23 on both sides of the second cold flow cavity 22 are arranged symmetrically relative to the outer contour center of the second cold flow cavity 22. For example, in an embodiment of the present invention, by symmetrically arranging the positions of the cold flow interfaces 23 on both sides relative to the geometric center of the side plate contour, the air flowing into the second cold flow cavity 22 from one side needs to flow through a certain amount before flowing out of another cold flow interface 23 on the other side, and the arrangement of the cold flow interfaces 23 on the corresponding first cold flow cavity 21 also adopts the same form. It is ensured that the low-temperature air can fully flow in the first cold flow cavity 21 and the second cold flow cavity 22 to exchange heat with the external heat source flow gas, further ensuring and improving the heat exchange efficiency.

[0044] Optionally, arc chamfers are provided at the outer contour edge corners of the first cold flow cavity 21 and the second cold flow cavity 22. Exemplarily, in the embodiment of the present invention, by performing arc chamfering treatment on the outer contour edge corners of the first cold flow cavity 21 and the second cold flow cavity 22, welding manufacturing is facilitated, and interference or collision damage with the inner shell chamber m during assembly into the shell can be reduced, thereby improving assembly convenience and overall service life.

[0045] Optionally, multiple groups of cold stream outlet holes 31 are provided, each group includes multiple cold stream outlet holes 31 arranged at equal angles around the circumference of the cold stream outlet pipe 3, and multiple groups of cold stream outlet holes 31 are evenly spaced along the extension direction of the cold stream outlet pipe 3. Exemplarily, in an embodiment of the present invention, multiple groups of cold stream outlet holes 31 arranged at equal angles around the circumference of the cold stream outlet pipe 3 are provided on the terminal section of the cold stream outlet pipe 3. It is ensured that the preheated air can fully and evenly flow into and diffuse into the interior of the battery stack, so as to facilitate the electrochemical reaction and power generation.

[0046] Optionally, a temperature sensor interface 32 is provided on the cold stream outlet pipe 3. Exemplarily, in an embodiment of the present invention, by providing a temperature sensor interface 32 on the cold stream outlet pipe 3, a temperature sensor can be provided there to detect the temperature of the air discharged into the fuel cell stack in real time, and feedback is given to the staff to observe whether the working condition of the heat exchanger is normal, so as to perform maintenance and adjustment in time.

[0047] Optionally, the air guide cavity 1, the first cold flow cavity 21, the second cold flow cavity 22 and the cold flow outlet pipe 3 are all stainless steel structural parts. For example, in the embodiment of the present invention, since the entire heat exchanger is usually maintained at a high temperature of more than 800°C inside the solid oxide fuel cell system to work, 310S stainless steel material is used to manufacture the entire heat exchanger structure, and its excellent performance of high temperature resistance, acid and alkali corrosion resistance is used to ensure the overall service life.

[0048] The present invention also provides a solid oxide fuel cell, comprising a plurality of Figures 1 to 8 Heat exchanger shown.

[0049] Fig. 9 : is a flow chart of the air preheating method provided by an embodiment of the present invention. Fig. 9 As shown, the embodiment of the present invention also provides an air preheating method based on Figures 1 to 8 The heat exchanger shown is implemented, comprising:

[0050] S1. Based on the specifications of the solid oxide fuel cell, an appropriate number of heat exchange units 2 are selected to be combined with the air guide cavity 1 and the cold stream outlet pipe 3 for connection and arrangement inside the solid oxide fuel cell.

[0051] S2. The heat source flow gas is introduced through the hot flow inlet m1 on the inner shell chamber m. The heat source flow gas flows through the flow channel space formed by the inner wall of the inner shell chamber m and the outer surfaces of the first cold flow cavity 21 and the second cold flow cavity 22, and finally flows out from the hot flow outlet cavity 12 to form a hot side circulation.

[0052] S3. Low-temperature air is introduced from the blower side through the cold flow inlet cavity 11. The low-temperature air flows through the first cold flow cavity 21 and the second cold flow cavity 22 and exchanges heat with the heat source flow gas to achieve preheating. Finally, the low-temperature air enters the cathode of the solid oxide fuel cell through the cold flow outlet hole 31 on the cold flow outlet pipe 3 to perform electrochemical reaction.

[0053] The heat exchanger structure provided in the embodiment of the present invention is adopted, and the air introduced into the solid oxide fuel cell is preheated by the above-mentioned air preheating method. Compared with the traditional heat exchanger form that uses fin plates to stack to form hot flow streams and cold flow streams, the inner shell chamber m in the solid oxide fuel cell system is directly used as part of the hot side cycle, and the plate-shaped first cold flow chamber 21 and the second cold flow chamber 22 are set in the inner shell chamber m by axial stacking as the cold flow stream flow channel for introducing air, and the outer contours of the two are distinguished to ensure that the heat source flow gas and air in the hot side cycle can achieve sufficient heat exchange. Through assembly and matching with the inner shell of the system, the heat exchange unit 2 can be increased or decreased according to the size specifications of the inner shell chamber m and the actual heat exchange requirements, and it is docked and welded and fixed by the cold flow interface 23, which is also simpler and more convenient than the sealing welding between the traditional fin plates. It can realize the miniaturization and lightweight of the heat exchanger and the entire solid oxide fuel cell on the basis of meeting the requirements of heat exchange efficiency, and improve integration and adaptability.

[0054] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0055] The above descriptions are merely optional embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat exchanger, arranged in an inner shell chamber (m) of a solid oxide fuel cell system, wherein a heat flow inlet (m1) is arranged on the wall of the inner shell chamber (m), characterized in that: include: An air guide cavity (1), a heat exchange unit (2) and a cold flow outlet pipe (3), The air guide cavity (1) comprises a cold flow inlet cavity (11) and a hot flow outlet cavity (12) which are isolated from each other; The heat exchange unit (2) is arranged in the inner shell chamber (m), and comprises a first cold flow chamber (21) and a second cold flow chamber (22) in the form of a plate. The first cold flow chamber (21) and the second cold flow chamber (22) are arranged in parallel and spaced apart, and are connected via a cold flow interface (23) arranged on adjacent side walls. In the spacing direction, the outer contour of the second cold flow chamber (22) is smaller than the outer contour of the first cold flow chamber (21). The heat exchange unit (2) is stacked in sequence and connected via the cold flow interface (23). The first cold flow cavity (21) located on one side in the stacking direction is connected to the outlet of the cold flow inlet cavity (11), and a hot flow flow hole (24) communicating with the hot flow outlet cavity (12) is provided in the middle; the second cold flow cavity (22) located on the other side in the stacking direction is connected to one end of the cold flow outlet pipe (3), the other end of the cold flow outlet pipe (3) is passed through the outside of the air guide cavity (1), and a cold flow outlet hole (31) is provided on the side wall.

2. The heat exchanger according to claim 1, characterized in that: The hot flow flow hole (24) is provided in the middle of each of the first cold flow chambers (21) in the plurality of heat exchange units (2).

3. The heat exchanger according to claim 2, characterized in that: The outer contour of the first cold flow cavity (21) is a square, and the outer contour of the second cold flow cavity (22) is a regular polygon.

4. The heat exchanger according to claim 3, characterized in that In the stacking direction, the cold flow interfaces (23) on both sides of the second cold flow cavity (22) are arranged symmetrically relative to the center of the outer contour of the second cold flow cavity (22).

5. The heat exchanger according to claim 3, characterized in that: Arc chamfers are provided at the corners of the outer contour edges of the first cold flow cavity (21) and the second cold flow cavity (22).

6. The heat exchanger according to claim 1, characterized in that The cold flow outlet holes (31) are provided in a plurality of groups, each group comprising a plurality of the cold flow outlet holes (31) arranged at equal angles around the circumference of the cold flow outlet pipe (3), and the plurality of groups of the cold flow outlet holes (31) are evenly spaced along the extension direction of the cold flow outlet pipe (3).

7. The heat exchanger according to claim 1, characterized in that The cold flow outlet pipe (3) is provided with a temperature sensor interface (32).

8. The heat exchanger according to claim 1, characterized in that The air guide cavity (1), the first cold flow cavity (21), the second cold flow cavity (22) and the cold flow outlet pipe (3) are all stainless steel structural parts.

9. A solid oxide fuel cell, characterized in that: The heat exchanger comprises a plurality of heat exchangers according to any one of claims 1 to 8.

10. An air preheating method, implemented based on the heat exchanger according to any one of claims 1 to 8, characterized in that: include: Based on the specifications of the solid oxide fuel cell, an appropriate number of groups of the heat exchange units (2) are selected to be combined and connected with the air guide cavity (1) and the cold stream outlet pipe (3) and arranged inside the solid oxide fuel cell; A heat source flow gas is introduced through the hot flow inlet (m1) on the inner shell chamber (m), and the heat source flow gas flows through the flow channel space formed by the inner side wall of the inner shell chamber (m) and the outer surfaces of the first cold flow cavity (21) and the second cold flow cavity (22), and finally flows out from the hot flow outlet cavity (12) to form a hot side circulation; Low-temperature air is introduced from the blower side through the cold flow inlet cavity (11), the low-temperature air flows through the first cold flow cavity (21) and the second cold flow cavity (22) and exchanges heat with the heat source flow gas to achieve preheating, and finally enters the cathode of the solid oxide fuel cell through the cold flow outlet hole (31) on the cold flow outlet pipe (3) to perform electrochemical reaction.

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