A compact fuel cell air system with efficient energy recovery

Abstract

This utility model relates to the field of fuel cell system technology, specifically disclosing a compact fuel cell air system with high-efficiency energy recovery. The fuel cell system includes a fuel cell stack, a centrifugal air compressor, a three-in-one valve, an air filter, a first flow sensor, an intercooler, a high-temperature cooling cycle system, a first temperature sensor, a first pressure sensor, a cathode steam-water separator, a drain valve, a second temperature sensor, a second pressure sensor, and a second flow sensor. The centrifugal air compressor includes a compressor and a variable geometry turboexpander. The three-in-one valve includes an inlet shut-off valve, an outlet shut-off valve, and a bypass valve. The intercooler is connected to the high-temperature cooling cycle system. The compact fuel cell air system with high-efficiency energy recovery provided by this utility model can more efficiently recover the energy from the low-flow residual air discharged from the fuel cell stack, while making the system more compact and reducing costs.

Description

Technical Field

[0001] This utility model relates to the field of fuel cell system technology, and in particular to a compact fuel cell air system with high-efficiency energy recovery. Background Technology

[0002] A fuel cell system is a device that uses hydrogen as fuel to generate electricity through the electrochemical reaction of hydrogen and oxygen. The efficiency and power density of a fuel cell have a significant impact on its application and widespread adoption. However, the need for an air compressor to pressurize the air consumes a large amount of power, reducing fuel cell efficiency. Recovering and utilizing the kinetic energy and heat of the residual air discharged from the fuel cell stack can help reduce air compressor power consumption and improve efficiency. At the same time, the complex air subsystem of a fuel cell affects its compactness and power density; therefore, optimizing the integration of air path valves to improve system compactness is of great significance.

[0003] Currently, most manufacturers use centrifugal air compressors with turbine expanders to recover energy from the residual air discharged from the fuel cell stack, converting the energy in the air into the mechanical energy of the air compressor's rotation. However, under idling or other low-load conditions, the airflow discharged from the fuel cell stack is small enough to drive the turbine in the expander to rotate, or the energy conversion efficiency is low, resulting in the inefficient recovery and utilization of the energy in the discharged residual air. Furthermore, the cathode subsystem has multiple valves, including infeed shut-off valves, outfeed shut-off valves, bypass valves, and exhaust back pressure valves, with numerous pipe connections between them, leading to a complex system that is large in size and weight, and expensive. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a compact fuel cell air system with high-efficiency energy recovery, which can more efficiently recover the energy of the low-flow residual air discharged from the fuel cell stack, while making the system more compact and reducing costs.

[0005] As one aspect of this utility model, a compact fuel cell air system with high-efficiency energy recovery is provided. The compact fuel cell air system with high-efficiency energy recovery includes a fuel cell stack, a centrifugal air compressor, a three-in-one valve, an air filter, a first flow sensor, an intercooler, a high-temperature cooling cycle system, a first temperature sensor, a first pressure sensor, a cathode steam-water separator, a drain valve, a second temperature sensor, a second pressure sensor, and a second flow sensor. The centrifugal air compressor includes a compressor and a variable geometry turboexpander. The three-in-one valve includes an infeed shut-off valve, an outfeed shut-off valve, and a bypass valve. The intercooler is connected to the high-temperature cooling cycle system.

[0006] One end of the air filter is connected to the outside, and the other end of the air filter is connected to one end of the compressor through the first flow sensor. The other end of the compressor is connected to one end of the infeed shut-off valve and one end of the bypass valve through the intercooler. The other end of the infeed shut-off valve is connected to the inlet of the fuel cell stack through the second flow sensor, the first temperature sensor, and the first pressure sensor in sequence. The outlet of the fuel cell stack is connected to one end of the outfeed shut-off valve through the second pressure sensor and the second temperature sensor in sequence. The other ends of the outfeed shut-off valve and the bypass valve are both connected to the inlet of the cathode steam-water separator. The liquid outlet of the cathode steam-water separator is connected to one end of the drain valve. The gas outlet of the cathode steam-water separator is connected to one end of the variable geometry turboexpander. The other ends of the variable geometry turboexpander and the drain valve are both connected to the outside.

[0007] Furthermore, the air filter is used to filter air drawn in from the outside. The filtered air passes through the first flow sensor and enters the compressor. The compressor compresses the air and sends it to the intercooler. The high-temperature cooling circulation system sends coolant to the intercooler. The coolant in the intercooler cools the high-pressure air inside the intercooler. The cooled high-pressure air enters the fuel cell stack through the inlet shut-off valve, or enters the cathode steam-water separator through the bypass valve.

[0008] After cooling, the high-pressure air enters the fuel cell stack and undergoes an electrochemical reaction with hydrogen to generate electricity. The remaining air after the reaction enters the exhaust pipe through the air outlet of the fuel cell stack, and then passes through the second pressure sensor and the second temperature sensor before entering the off-state valve. The air flowing out of the off-state valve and the air flowing out of the bypass valve merge and are discharged through the outlet on the tail side of the three-in-one valve to the cathode steam-water separator. The cathode steam-water separator is used to separate liquid water from the air and discharge the separated liquid from the liquid outlet of the cathode steam-water separator, and then discharge it from the system through the drain valve. At the same time, the cathode steam-water separator discharges the air after water separation from the gas outlet of the cathode steam-water separator to the variable geometry turbine expander to do work, converting the energy of the air into the rotational mechanical energy of the turbine in the variable geometry turbine expander. The air after doing work is discharged from the outlet of the variable geometry turbine expander and finally discharged from the system.

[0009] Furthermore, the first flow sensor is used to detect the current flow rate of air entering the compressor; the second flow sensor, the first temperature sensor, and the first pressure sensor are used to detect the current flow rate, current temperature, and current pressure of air entering the fuel cell stack, respectively; the second temperature sensor and the second pressure sensor are used to detect the current temperature and current pressure of air flowing out of the fuel cell stack, respectively.

[0010] Furthermore, during operation, the impeller in the compressor and the turbine in the variable cross-section turbine expander are mounted on the same shaft and rotate synchronously. The air discharged from the gas outlet of the cathode steam-water separator drives the turbine to rotate in the variable cross-section turbine expander, which in turn drives the impeller to rotate synchronously.

[0011] Furthermore, the centrifugal air compressor also includes a motor, which, together with the air discharged from the gas outlet of the cathode steam-water separator, drives the compressor and the variable cross-section turboexpander to rotate synchronously.

[0012] Furthermore, when the current airflow rate discharged from the gas outlet of the cathode steam-water separator is less than a preset value, the current opening of the variable cross-section in the variable cross-section turbine expander is reduced; when the current airflow rate discharged from the gas outlet of the cathode steam-water separator is greater than the preset value, the current opening of the variable cross-section in the variable cross-section turbine expander is increased; wherein, the current back pressure of the compact fuel cell system is adjusted by adjusting the current opening of the variable cross-section in the variable cross-section turbine expander.

[0013] Furthermore, the infeed shut-off valve, outfeed shut-off valve, and bypass valve in the three-in-one valve are integrated into one unit, and a set of drive modules is used to drive the infeed shut-off valve, outfeed shut-off valve, and bypass valve to rotate synchronously, so that the three-in-one valve has three position states.

[0014] First position state: Infeed shut-off valve and outfeed shut-off valve are fully open, bypass valve is fully closed;

[0015] The second position state: the infeed shut-off valve and the outfeed shut-off valve are partially open, the bypass valve is partially open, and the opening degree of the three valves can be adjusted synchronously within a certain range according to the operating conditions.

[0016] The third position state: the infeed shut-off valve and the outfeed shut-off valve are both closed, and the bypass valve is fully open.

[0017] This utility model provides a compact fuel cell air system with high-efficiency energy recovery, which has the following advantages: it adopts an air compressor equipped with a variable cross-section turbine expander and a combination of three-in-one valves, which can more efficiently recover the energy of the low-flow residual air discharged from the fuel cell stack. At the same time, the back pressure valve can be eliminated, and the in-stack shut-off valve, out-stack shut-off valve and bypass valve are integrated into one unit, reducing the number of valve drive modules and pipelines used, making the system more compact and reducing costs. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof.

[0019] Figure 1 This is a structural diagram of a compact fuel cell air system with high-efficiency energy recovery according to an embodiment of the present invention.

[0020] Figure 2A This is a schematic diagram of the first position state of the three-in-one valve in this embodiment of the present invention.

[0021] Figure 2B This is a schematic diagram of the second position state of the three-in-one valve in an embodiment of this utility model.

[0022] Figure 2C This is a schematic diagram of the third position state of the three-in-one valve in this embodiment of the present invention.

[0023] Figure 3 This is a flowchart illustrating a control method for a compact fuel cell air system with high-efficiency energy recovery, as described in an embodiment of this utility model.

[0024] The components represented by each number in the attached diagram are listed below: 1. Fuel cell stack; 2. Centrifugal air compressor; 2-1. Compressor; 2-2. Variable geometry turboexpander; 3. Three-in-one valve; 3-1. Infeed shut-off valve; 3-2. Outfeed shut-off valve; 3-3. Bypass valve; 4. Air filter; 5. First flow sensor; 6. Intercooler; 7. High-temperature cooling cycle system; 8. First temperature sensor; 9. First pressure sensor; 10. Cathode steam-water separator; 11. Drain valve; 12. Second temperature sensor; 13. Second pressure sensor; 14. Second flow sensor. Detailed Implementation

[0025] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0028] This invention provides a compact fuel cell air system with high-efficiency energy recovery, such as... Figure 1 As shown, the compact fuel cell air system with high-efficiency energy recovery includes a fuel cell stack 1, a centrifugal air compressor 2, a three-in-one valve 3, an air filter 4, a first flow sensor 5, an intercooler 6, a high-temperature cooling cycle system 7, a first temperature sensor 8, a first pressure sensor 9, a cathode steam-water separator 10, a drain valve 11, a second temperature sensor 12, a second pressure sensor 13, and a second flow sensor 14. The centrifugal air compressor 2 includes a compressor 2-1 and a variable geometry turboexpander 2-2. The three-in-one valve 3 includes an infeed shut-off valve 3-1, an outfeed shut-off valve 3-2, and a bypass valve 3-3. The intercooler 6 is connected to the high-temperature cooling cycle system 7.

[0029] One end of the air filter 4 is connected to the outside, and the other end of the air filter 4 is connected to one end of the compressor 2-1 through the first flow sensor 5. The other end of the compressor 2-1 is connected to one end of the inlet shut-off valve 3-1 and one end of the bypass valve 3-3 through the intercooler 6. The other end of the inlet shut-off valve 3-1 is connected to the inlet of the fuel cell stack 1 through the second flow sensor 14, the first temperature sensor 8 and the first pressure sensor 9 in sequence. The outlet of the fuel cell stack 1 is connected to one end of the outlet shut-off valve 3-2 through the second pressure sensor 13 and the second temperature sensor 12 in sequence. The other ends of the outlet shut-off valve 3-2 and the bypass valve 3-3 are both connected to the inlet of the cathode steam-water separator 10. The liquid outlet of the cathode steam-water separator 10 is connected to one end of the drain valve 11. The gas outlet of the cathode steam-water separator 10 is connected to one end of the variable geometry turboexpander 2-2. The other ends of the variable geometry turboexpander 2-2 and the drain valve 11 are both connected to the outside.

[0030] It should be noted that the high-temperature cooling circulation system 7 includes radiators, water tanks, fans, water pumps, valves, temperature sensors, etc., which are technologies well known to those skilled in the art and will not be described in detail here.

[0031] Preferably, according to the airflow direction of the cathode subsystem, the air filter 4 is used to filter the air drawn in from the outside to remove particulate matter and impurities. The filtered air passes through the first flow sensor 5 and enters the compressor 2-1. The compressor 2-1 compresses the air and sends it to the intercooler 6. The high-temperature cooling circulation system 7 sends coolant to the intercooler 6. The coolant in the intercooler 6 cools the high-pressure air in the intercooler 6 to the required temperature. The cooled high-pressure air enters the fuel cell stack 1 through the inlet shut-off valve 3-1, or enters the cathode steam-water separator 10 through the bypass valve 3-3.

[0032] After cooling, the high-pressure air enters the fuel cell stack 1 and undergoes an electrochemical reaction with hydrogen to generate electricity. The remaining air after the reaction enters the exhaust pipe through the air outlet of the fuel cell stack 1, then passes through the second pressure sensor 13 and the second temperature sensor 12 before entering the outflow shut-off valve 3-2. The air flowing out of the outflow shut-off valve 3-2 and the air flowing out of the bypass valve 3-3 merge and are discharged through the tail outlet of the three-in-one valve 3 to the cathode steam-water separator 10. The cathode steam-water separator 10 is used for... The process separates liquid water from the air and discharges the separated liquid from the liquid outlet of the cathode steam-water separator 10, and then discharges it from the system through the drain valve 11. Simultaneously, the cathode steam-water separator 10 discharges the air after water separation from its gas outlet into the variable cross-section turbine expander 2-2 to perform work, converting the energy of the air into the rotational mechanical energy of the turbine in the variable cross-section turbine expander 2-2. The air after work is discharged from the outlet of the variable cross-section turbine expander 2-2 and finally discharged from the system.

[0033] Preferably, the first flow sensor 5 is used to detect the current flow rate of air entering the compressor 2-1; the second flow sensor 14, the first temperature sensor 8 and the first pressure sensor 9 are used to detect the current flow rate, current temperature and current pressure of air entering the fuel cell stack 1, respectively; the second temperature sensor 12 and the second pressure sensor 13 are used to detect the current temperature and current pressure of air flowing out of the fuel cell stack 1, respectively.

[0034] Preferably, during operation, the impeller in the compressor 2-1 and the turbine in the variable cross-section turbine expander 2-2 are mounted on the same shaft and rotate synchronously. Therefore, the air discharged from the gas outlet of the cathode steam-water separator 10 drives the turbine to rotate in the variable cross-section turbine expander 2-2, which in turn drives the impeller to rotate synchronously.

[0035] Preferably, the centrifugal air compressor 2 further includes a motor, which, together with the air discharged from the gas outlet of the cathode steam-water separator 10, drives the compressor 2-1 and the variable cross-section turbine expander 2-2 to rotate synchronously.

[0036] Preferably, the variable cross-section of the variable cross-section turbine expander 2-2 has an adjustable opening. When the current airflow rate discharged from the gas outlet of the cathode steam-water separator 10 is less than a preset value, the current opening of the variable cross-section of the variable cross-section turbine expander 2-2 is reduced to increase the airflow velocity, widen the operating range of the variable cross-section turbine expander 2-2, and enable low-flow air to effectively perform work on the turbine of the variable cross-section turbine expander 2-2, achieving energy recovery. When the current airflow rate discharged from the gas outlet of the cathode steam-water separator 10 is greater than the preset value, the current opening of the variable cross-section of the variable cross-section turbine expander 2-2 is increased to prevent the air compressor 2 from stalling. When the variable cross-section of the variable cross-section turbine expander 2-2 changes, the back pressure of the system will change. When the variable cross-section opening is increased, the back pressure decreases; when the variable cross-section is decreased, the back pressure increases. Therefore, the system back pressure valve can be eliminated, and the current back pressure of the compact fuel cell system can be adjusted by adjusting the current opening of the variable cross-section of the variable cross-section turbine expander 2-2.

[0037] Preferably, the infeed shut-off valve 3-1, outfeed shut-off valve 3-2, and bypass valve 3-3 in the three-in-one valve 3 are integrated into one unit, and a single drive module drives the infeed shut-off valve 3-1, outfeed shut-off valve 3-2, and bypass valve 3-3 to rotate synchronously, thereby improving system integration and reducing system size, weight, and cost. The three-in-one valve 3 has three position states;

[0038] like Figure 2A As shown, the first position state is: the infeed shut-off valve 3-1 and the outfeed shut-off valve 3-2 are fully open, and the bypass valve 3-3 is fully closed.

[0039] like Figure 2B As shown, in the second position state: the infeed shut-off valve 3-1 and the outfeed shut-off valve 3-2 are partially open, the bypass valve 3-3 is partially open, and the opening of the three valves can be adjusted synchronously within a certain range according to the operating conditions.

[0040] like Figure 2C As shown, the third position state is: the infeed shut-off valve 3-1 and the outfeed shut-off valve 3-2 are fully closed, and the bypass valve 3-3 is fully open.

[0041] It should be noted that the drive module includes motors, gears, rods, etc., which are technologies well known to those skilled in the art and will not be described in detail here.

[0042] It should be noted that, based on the demand for electrical energy output from the fuel cell system and the system status detected by various sensors in the fuel cell system, the target flow rate and target pressure of the air entering the fuel cell stack 1 and the target pressure of the air flowing out of the fuel cell stack 1 are calculated. Then, based on the detected current flow rate and current pressure of the air entering the fuel cell stack 1 and the current pressure of the air flowing out of the fuel cell stack 1, as well as the target flow rate and target pressure of the air entering the fuel cell stack 1 and the target pressure of the air flowing out of the fuel cell stack 1, the air compressor speed is controlled, and the three-in-one valve 3 is controlled to switch between three position states.

[0043] In this embodiment of the utility model, (1) the centrifugal air compressor is an expander with a variable cross section; (2) the opening of the variable cross section of the expander is dynamically adjusted according to the system operating conditions. The opening of the variable cross section is reduced under low flow rate to achieve efficient recovery of air energy under low flow rate, and the opening of the variable cross section is increased under high flow rate to prevent the air compressor from stalling; (3) the opening of the variable cross section of the expander can also be adjusted according to the system operating conditions to adjust the back pressure of the fuel cell outlet air path, thereby replacing the use of the back pressure valve; (4) a three-in-one valve for controlling the air flow rate in and out of the fuel cell and bypass is provided, which integrates the functions of the inlet air shut-off valve, the outlet air shut-off valve and the bypass valve; (5) The three-in-one valve uses a set of drive modules to drive the three built-in valves to rotate synchronously, so that the three-in-one valve has three position states; the first position state of the three-in-one valve: the in-reactor shut-off valve and the out-reactor shut-off valve are fully open, and the bypass valve is fully closed; the second position state of the three-in-one valve: the in-reactor shut-off valve and the out-reactor shut-off valve are partially open, the bypass valve is partially open, and the opening degree of the three valves can be adjusted synchronously within a certain range according to the working conditions; the third position state of the three-in-one valve: the in-reactor shut-off valve and the out-reactor shut-off valve are fully closed, and the bypass valve is fully open; (6) the three valves inside the three-in-one valve can be lift valves or butterfly valves or other structures or combinations that can meet the functional requirements.

[0044] In this embodiment of the invention, the fuel cell cathode subsystem integrates a centrifugal air compressor with a variable cross-section expander and a three-in-one valve for controlling air intake, exhaust, and bypass. By combining the proposed control method, the air compressor speed, variable cross-section expander opening, and three-in-one valve position can be adjusted according to the system operating conditions, thereby improving the system's energy recovery efficiency, simplifying the system structure, making the system more compact, reducing size and weight, and lowering costs.

[0045] This utility model embodiment also provides a control method for a compact fuel cell air system with high-efficiency energy recovery, such as... Figure 3 As shown, the control method for the compact fuel cell air system with high-efficiency energy recovery includes the following steps:

[0046] Step 1: Begin;

[0047] Step 2: Start cathode purging, control the centrifugal air compressor 2 to operate at the first predetermined purging speed, and control the three-in-one valve 3 to maintain the third position state. At this time, air enters the tail exhaust side of the three-in-one valve 3 through the bypass valve 3-3 to dilute the hydrogen concentration on the tail exhaust side; then reduce the opening of the variable cross section in the variable cross section turbine expander 2-2 to recover energy.

[0048] Step 3: After purging, the fuel cell system operates according to the output operating conditions. The central controller determines whether the compact fuel cell system is currently in normal operation based on the real-time detection results of the second flow sensor 14, the first pressure sensor 9, and the second pressure sensor 13. If the compact fuel cell system is currently in normal operation, then proceed to step 4; if the compact fuel cell system is currently in a surge state, then proceed to step 5.

[0049] Step 4: Control the three-in-one valve 3 to move to the first position state, and calculate the target flow rate and target pressure of the air entering the fuel cell stack 1 and the target pressure of the air flowing out of the fuel cell stack 1 according to the system operating conditions. Based on the air circuit system model and system calibration results, control the speed of the centrifugal air compressor 2 and the opening of the variable section in the variable section turbine expander 2-2; then execute step 6.

[0050] Step 5: Increase the speed of the centrifugal air compressor 2 to increase the total air flow of the compact fuel cell system, and increase the opening of the variable section in the variable section turbine expander 2-2. Then control the three-in-one valve 3 to move to the second position state so that the excess air flow is discharged through the bypass valve 3-3. Then determine whether the compact fuel cell system is currently in normal operation. If yes, return to step 4; if no, proceed to step 6.

[0051] Step 6: Enter the shutdown procedure;

[0052] Step 7: Perform cathode purging, control the centrifugal air compressor 2 to operate at the second predetermined purging speed, and control the three-in-one valve 3 to move to the first position state, and then increase the opening of the variable section in the variable section turbine expander 2-2.

[0053] Step 8: After the cathode purging is completed, control the centrifugal air compressor 2 to continue running at the third predetermined purging speed, and control the three-in-one valve 3 to move to the third position state. Then, adjust the opening of the variable section in the variable section turbine expander 2-2 back to the default value.

[0054] Step 9: The oxygen in the fuel cell stack is depleted;

[0055] Step 10: Shut down the machine.

[0056] The present invention provides a control method for a compact fuel cell air system with high-efficiency energy recovery. Based on the detected air pressure, air flow, and air temperature, and according to the operating conditions and requirements of the fuel cell, the method calculates and controls the speed of the centrifugal air compressor 2, the cross-sectional opening of the variable section turbine expander 2-2, and the position of the three-in-one valve 3. This method improves energy recovery efficiency at low flow rates, avoids air compressor stall at high flow rates, and simultaneously achieves system back pressure regulation and surge suppression.

[0057] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this utility model, and the utility model is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of this utility model, and these modifications and improvements are also considered to be within the protection scope of this utility model.

Claims

1. A compact fuel cell air system with high energy recovery, characterized by, The compact fuel cell air system with high-efficiency energy recovery includes a stack (1), a centrifugal air compressor (2), a three-in-one valve (3), an air filter (4), a first flow sensor (5), an intercooler (6), a high-temperature cooling cycle system (7), a first temperature sensor (8), a first pressure sensor (9), a cathode steam-water separator (10), a drain valve (11), a second temperature sensor (12), a second pressure sensor (13), and a second flow sensor (14). The centrifugal air compressor (2) includes a compressor (2-1) and a variable geometry turboexpander (2-2). The three-in-one valve (3) includes an infeed shut-off valve (3-1), an outfeed shut-off valve (3-2), and a bypass valve (3-3). The intercooler (6) is connected to the high-temperature cooling cycle system (7). One end of the air filter (4) is connected to the outside, and the other end of the air filter (4) is connected to one end of the compressor (2-1) through the first flow sensor (5). 1) The other end is connected to one end of the inlet shut-off valve (3-1) and one end of the bypass valve (3-3) respectively through the intercooler (6). The other end of the inlet shut-off valve (3-1) is connected to the inlet of the fuel cell stack (1) through the second flow sensor (14), the first temperature sensor (8) and the first pressure sensor (9) in sequence. The outlet of the fuel cell stack (1) is connected to the outlet shut-off valve (3-3) in sequence through the second pressure sensor (13) and the second temperature sensor (12). 2) One end of the reactor shut-off valve (3-2) and the other end of the bypass valve (3-3) are both connected to the inlet of the cathode steam-water separator (10). The liquid outlet of the cathode steam-water separator (10) is connected to one end of the drain valve (11). The gas outlet of the cathode steam-water separator (10) is connected to one end of the variable cross section turbine expander (2-2). The other end of the variable cross section turbine expander (2-2) and the other end of the drain valve (11) are both connected to the outside. Among them, the infeed shut-off valve (3-1), outfeed shut-off valve (3-2) and bypass valve (3-3) in the three-in-one valve (3) are integrated into one unit, and a set of drive modules is used to drive the infeed shut-off valve (3-1), outfeed shut-off valve (3-2) and bypass valve (3-3) to rotate synchronously, so that the three-in-one valve (3) has 3 position states; First position state: Infeed shut-off valve (3-1) and outfeed shut-off valve (3-2) are fully open, and bypass valve (3-3) is fully closed; The second position state: the infeed shut-off valve (3-1) and the outfeed shut-off valve (3-2) are partially open, the bypass valve (3-3) is partially open, and the opening degree of the three valves can be adjusted synchronously within a certain range according to the working conditions; The third position state: the infeed shut-off valve (3-1) and the outfeed shut-off valve (3-2) are fully closed, and the bypass valve (3-3) is fully open.

2. The compact fuel cell air system with high power energy recovery of claim 1, wherein, The air filter (4) is used to filter the air drawn in from the outside. The filtered air passes through the first flow sensor (5) and enters the compressor (2-1). The compressor (2-1) compresses the air and sends it into the intercooler (6). The high-temperature cooling circulation system (7) sends coolant into the intercooler (6). The coolant in the intercooler (6) cools the high-pressure air in the intercooler (6). The cooled high-pressure air enters the fuel cell stack (1) through the inlet shut-off valve (3-1) or enters the cathode steam-water separator (10) through the bypass valve (3-3). After cooling, the high-pressure air enters the fuel cell stack (1) and undergoes an electrochemical reaction with hydrogen to generate electricity. The remaining air after the reaction enters the exhaust pipe through the air outlet of the fuel cell stack (1), and then enters the outflow shut-off valve (3-2) after passing through the second pressure sensor (13) and the second temperature sensor (12). The air flowing out of the outflow shut-off valve (3-2) and the air flowing out of the bypass valve (3-3) merge and are discharged into the cathode steam-water separator (10) through the tail outlet of the three-in-one valve (3). 0) is used to separate liquid water in the air and discharge the separated liquid from the liquid outlet of the cathode steam-water separator (10) and discharge it from the system through the drain valve (11); at the same time, the cathode steam-water separator (10) discharges the air after water separation from the gas outlet of the cathode steam-water separator (10) to the variable cross section turbine expander (2-2) to do work, converting the energy of the air into the rotational mechanical energy of the turbine in the variable cross section turbine expander (2-2), and the air after doing work is discharged from the outlet of the variable cross section turbine expander (2-2) and finally discharged from the system.

3. The compact fuel cell air system with high power energy recovery of claim 2, wherein, The first flow sensor (5) is used to detect the current flow rate of air entering the compressor (2-1); the second flow sensor (14), the first temperature sensor (8) and the first pressure sensor (9) are used to detect the current flow rate, current temperature and current pressure of air entering the fuel cell stack (1) respectively; the second temperature sensor (12) and the second pressure sensor (13) are used to detect the current temperature and current pressure of air flowing out of the fuel cell stack (1) respectively.

4. The compact fuel cell air system with high power energy recovery of claim 2, wherein, During operation, the impeller in the compressor (2-1) and the turbine in the variable cross-section turbine expander (2-2) are mounted on the same shaft and rotate synchronously. The air discharged from the gas outlet of the cathode steam-water separator (10) drives the turbine to rotate in the variable cross-section turbine expander (2-2), which in turn drives the impeller to rotate synchronously. The centrifugal air compressor (2) also includes a motor. The motor and the air discharged from the gas outlet of the cathode steam-water separator (10) jointly drive the compressor (2-1) and the variable cross-section turbine expander (2-2) to rotate synchronously.

5. The compact fuel cell air system with high-efficiency energy recovery according to claim 2, characterized in that, When the current airflow rate discharged from the gas outlet of the cathode steam-water separator (10) is less than a preset value, the current opening of the variable cross section in the variable cross section turbine expander (2-2) is reduced; when the current airflow rate discharged from the gas outlet of the cathode steam-water separator (10) is greater than a preset value, the current opening of the variable cross section in the variable cross section turbine expander (2-2) is increased; wherein, the current back pressure of the compact fuel cell air system is adjusted by adjusting the current opening of the variable cross section in the variable cross section turbine expander (2-2).

Images