Ejector and gas supply circulation system for fuel cell

Abstract

The present application relates to the field of ejectors, and specifically discloses an ejector, wherein the gas supply circulation system used by the ejector includes: a fuel cell, a target gas source, a pressure regulating valve, an ejector, and a switch valve; the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source; the working inlet of the ejector is connected to the target gas source, the target gas discharged from the fuel cell enters the ejector through the ejection inlet, and is mixed with the target gas inputted from the working inlet, and the mixed target gas is outputted to the fuel cell through the ejector outlet; the ejector is applied to N working conditions, and the N working conditions correspond to the N achievable ejection coefficients one by one, and under each working condition in the N working conditions, the designed ejection coefficient of the ejector is less than the achievable ejection coefficient corresponding to each working condition. The ejector provided in the present application can provide a constant working flow rate for the fuel cell in all working conditions, as well as a hydrogen circulation amount that meets the requirements of the fuel cell.

Description

Technical Field

[0001] The present application relates to the technical field of ejectors, and in particular to an ejector and a gas supply circulation system for a fuel cell. Background Art

[0002] The hydrogen circuit of the fuel cell requires an excess supply of hydrogen. To improve the utilization rate of hydrogen, a common solution is to establish a hydrogen recycling system to send the unreacted hydrogen at the outlet of the stack back to the inlet after gas-water separation and mix it with the main gas circuit for reuse, thus achieving the effect of hydrogen circulation and inlet hydrogen humidification. There are no moving parts in the ejector, so the mechanical stability is better, and it has incomparable advantages over mechanical pumps in terms of volume and weight. Therefore, the ejector is often used in hydrogen supply and circulation systems.

[0003] In actual use, the unreasonable structural design of the ejector will cause the working range of the gas supply circulation system in which it is located to be too narrow and unable to adapt to the full operating conditions of the fuel cell stack. Specifically, when the fuel cell stack consumption is at any of the maximum, minimum, larger, and smaller conditions, the ejector capacity may be insufficient. The ejector with an unreasonable structural design has a weak ability to adapt to the variable load of the fuel cell stack. Therefore, it is difficult to ensure the working stability of the single ejector system when the fuel cell is started and stopped and the load changes. How to optimize the ejector structure to ensure that the ejection amount provided by the ejector is not less than the excess hydrogen circulation amount of the fuel cell stack is a technical problem that needs to be solved. Summary of the invention

[0004] The present application provides an ejector and a gas supply circulation system for a fuel cell, with the aim of providing an ejector with a rationally designed structure. When the ejector is applied to the gas supply circulation system provided by the present application, it can provide a constant working flow rate for the fuel cell under all working conditions when the working pressure is constant, as well as a hydrogen circulation amount that meets the requirements of the fuel cell.

[0005] In a first aspect, an ejector is provided, wherein the ejector is applied to a gas supply circulation system, and the gas supply circulation system comprises:

[0006] Fuel cells;

[0007] a target gas source, for supplying a target gas to the fuel cell;

[0008] A pressure regulating valve and an ejector, wherein the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source;

[0009] The ejector comprises a working inlet, an ejector inlet and an ejector outlet, wherein the working inlet is connected to the target gas source, the target gas discharged from the fuel cell enters the ejector through the ejector inlet, and is mixed with the target gas input from the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet;

[0010] The ejector is applied to N working conditions, and the ejector satisfies:

[0011] Under the target operating condition among the N operating conditions, the design ejection coefficient of the ejector is less than the achievable ejection coefficient corresponding to the target operating condition,

[0012] Under other working conditions among the N working conditions, the actual ejection coefficient of the ejector in the working condition is not less than the designed ejection system corresponding to the working condition of the ejector.

[0013] Compared with the prior art, the solution provided by this application includes at least the following beneficial technical effects:

[0014] The ejector designed in this application can be adapted to a new type of hydrogen supply and circulation system in which a pressure regulating valve and an ejector are connected in parallel, which can ensure a constant working flow rate in all working conditions and a hydrogen circulation volume that is not less than the fuel cell's demand. While ensuring that sufficient hydrogen is supplied to the fuel cell stack in all working conditions, the control difficulty of the regulating valve is reduced, and the outlet pressure vibration caused by the coupling of the synchronous flow fluctuation of the pressure regulating valve and the ejector is avoided.

[0015] In combination with the first aspect, in certain implementations of the first aspect, the N operating conditions correspond one-to-one to N achievable injection coefficients, and the achievable injection coefficient corresponding to the target operating condition is the minimum value of the N achievable injection coefficients.

[0016] Ensuring that the minimum value of the N achievable ejection coefficients is greater than the design ejection coefficient under all operating conditions and ensuring that the ejection flow rate of the ejector is greater than the hydrogen circulation volume required for the current operating conditions is helpful to reduce the workload of ejection capability verification under N operating conditions.

[0017] In combination with the first aspect, in certain implementations of the first aspect, the designed ejection coefficient U=G h / G P , the ejection flow rate G of the ejector h =Q×(i-1), the ejector working flow G P =G 最小消耗 -G 压力调节阀 , Q is the maximum stack consumption or the stack consumption under the working condition corresponding to the design ejection coefficient, i is the excess coefficient, G 最小消耗 The minimum stack consumption when the gas supply circulation system opens the ejector, G 压力调节阀is the minimum flow adjustment value of the pressure regulating valve.

[0018] When the design ejection coefficient is calculated using the maximum stack consumption, an ejector that meets all operating conditions can be obtained through a single design.

[0019] In combination with the first aspect, in some implementations of the first aspect, the achievable ejection coefficient u satisfies:

[0020]

[0021]

[0022]

[0023] Nozzle velocity coefficient Velocity coefficient of the mixing chamber Velocity coefficient of diffuser Velocity coefficient at the inlet section of the mixing chamber Δp c =p c -p H ;P c -P h =ξ 电堆 *(Q 消耗 +G h ) 2 / ρ 饱和湿氢气 +ξ 气水分离 *G h 2 / ρ 饱和湿氢气 ;

[0024] υ p is the specific volume of the working gas; H is the specific volume of the ejected gas; c is the specific volume of the mixed gas;

[0025] p p is the working gas pressure; p H is the ejection gas pressure; p c is the pressure of the mixed gas;

[0026] k p is the working gas adiabatic index; k H is the adiabatic index of the ejected gas; k c is the adiabatic index of the mixed gas;

[0027] λ pH is the converted isentropic velocity; n = 1.01 ~ 1.08.

[0028] In combination with the first aspect, in certain implementations of the first aspect, when the stack consumption is the largest, the working gas pressure P of the ejector isp and the ejected gas pressure P h satisfy:

[0029] The expansion ratio P of the working gas in the ejector P / P h Greater than the critical pressure ratio.

[0030] This is beneficial to the stable operation of the ejector.

[0031] In combination with the first aspect, in certain implementations of the first aspect, the nozzle throat diameter of the ejector is is the critical area of ​​the nozzle throat;

[0032] In combination with the first aspect, in certain implementations of the first aspect, the nozzle opening diameter of the ejector is q p1 The expansion ratio P in the N working conditions P / P h corresponds to the minimum value in .

[0033] In combination with the first aspect, in certain implementations of the first aspect, the diameter of the ejector mixing chamber is |f p3 -f3|≤preset threshold;

[0034] In combination with the first aspect, in some implementations of the first aspect, d4=1.55d p1 (1+u), the distance between the ejector nozzle and the mixing chamber is l c satisfy:

[0035] When d3>d4, l c = l c1 , l c1 is the length of the free stream at the nozzle outlet, j is an experimental constant;

[0036] When d3<d4, l c = l c1 +l c2 , l c2 is the length of the mixing chamber inlet section, and β is the cone angle of the mixing inlet section.

[0037] In combination with the first aspect, in certain implementations of the first aspect, the length l of the ejector mixing chamber is K It is 6 to 10 times the diameter d3 of the mixing chamber.

[0038] In a second aspect, a gas supply circulation system is provided, the gas supply circulation system comprising:

[0039] Fuel cells;

[0040] a target gas source, for supplying a target gas to the fuel cell;

[0041] A pressure regulating valve and an ejector as described in any one of the implementations of the first aspect above, wherein the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source;

[0042] The ejector includes a working inlet, an ejector inlet and an ejector outlet. The working inlet is connected to the target gas source. The target gas discharged from the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input from the working inlet. The mixed target gas is output to the fuel cell through the ejector outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic structural diagram of a gas supply circulation system provided in an embodiment of the present application.

[0044] Figure 2 A schematic structural diagram of an ejector provided in an embodiment of the present application.

[0045] Figure 3 A schematic structural diagram of an ejector provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] The present application embodiment discloses a gas supply circulation system, referring to Figure 1 , including a hydrogen source, a first-stage pressure reducing valve, a pressure regulating valve, a switch valve, an ejector, and a fuel cell.

[0048] The hydrogen source can supply hydrogen to the fuel cell and provide the required hydrogen consumption for the fuel cell stack. The pressure regulating valve and the ejector are connected in parallel between the fuel cell and the hydrogen source. After the hydrogen flows out of the hydrogen source, it is reduced in pressure by the primary pressure reducing valve and enters the pressure regulating valve branch and the solenoid valve and ejector branch respectively. Figure 1 As shown, a pressure sensor P0 can be provided at the outlet side of the first-stage pressure reducing valve. The first-stage pressure reducing valve can be used to reduce the pressure of the hydrogen source and ensure that the pressure value at the front end of the pressure regulating valve and the ejector remains constant.

[0049] Figure 2 is a schematic structural diagram of an ejector provided in an embodiment of the present application. Figure 1 and Figure 2 The ejector includes a working inlet, an ejector inlet and an ejector outlet. The ejector nozzle is arranged at the working inlet. The mixing chamber of the ejector can be located on a side of the ejector nozzle close to the ejector outlet. The mixing chamber can be connected between the receiving chamber and the diffusion chamber of the ejector.

[0050] The working inlet can be connected to the hydrogen source through a switch valve. The switch valve can be used to control whether the ejector supplies hydrogen to the fuel cell. When the fuel cell stack consumption is relatively small, the supply of the pressure regulating valve is sufficient to provide hydrogen to the fuel cell. At this time, the switch valve can be disconnected, thereby controlling the ejector not to supply hydrogen to the fuel cell. Figure 1 As shown, a pressure sensor P1 can be provided at the outlet side of the pressure regulating valve. By setting the inlet pressure corresponding to the fuel cell operating condition as the target pressure and controlling the outlet pressure of the pressure sensor to be consistent with the target pressure, the opening of the pressure regulating valve can be adjusted to ensure the hydrogen supply at the inlet side of the fuel cell.

[0051] When the stack consumption of the fuel cell is relatively large, the amount of hydrogen required by the fuel cell gradually approaches the maximum supply capacity of the pressure regulating valve. At this time, the switch valve can be opened to control the ejector to supply hydrogen to the fuel cell. Hydrogen from the hydrogen source can enter the ejector through the working inlet of the ejector and be output to the fuel cell from the ejector outlet of the ejector. The excess hydrogen tail gas of the fuel cell can be circulated through the ejector. Driven by the high-pressure hydrogen flow at the working inlet of the fuel cell, the excess hydrogen discharged by the fuel cell can enter the ejector through the ejector inlet. The hydrogen input from the ejector inlet can be mixed with the hydrogen input from the working inlet. The mixed hydrogen can be output to the fuel cell through the ejector outlet. The hydrogen circulation amount of the excess coefficient required by the stack is thereby ensured. In some embodiments, the switch valve may be a solenoid valve.

[0052] In some embodiments provided in the present application, when the stack consumption of the fuel cell is greater than the working flow of the ejector, the switch valve can be opened. The principle of opening the switch valve is described below. The stack consumption can usually correspond to the stack loading current of the fuel cell. The greater the stack consumption, the higher the stack loading current of the fuel cell. When the stack consumption is small, the amount of hydrogen required by the fuel cell is small, and the working flow of the ejector exceeds the stack consumption, and the switch valve is closed. By controlling the outlet side pressure of the pressure regulating valve, the flow rate conducted by the pressure regulating valve can be controlled.

[0053] As the consumption of the stack gradually increases, the amount of hydrogen required by the fuel cell also gradually increases. When the required hydrogen flow exceeds the part greater than the working flow of the ejector and is greater than the minimum flow of the pressure regulating valve regulating flow range, the switch valve opens, and the ejector can cooperate with the pressure regulating valve to supply hydrogen to the fuel cell. Since the pressure on the working inlet side of the ejector can be kept constant by the first-stage pressure reducing valve, the ejector working pressure operates at the designed working pressure Pp in the full operating condition, the flow rate at the nozzle throat of the ejector can reach the critical speed, and the working flow of the ejector is constant, providing a constant partial consumption for the stack. Within its operating range, the ejector can also provide the stack with an ejection flow corresponding to the hydrogen excess coefficient required by the stack. When the stack consumption of the fuel cell is at a relatively medium level, the opening of the pressure regulating valve can be relatively small, and the hydrogen required by the fuel cell can be mainly provided by the ejector. As the consumption of the stack of the fuel cell gradually increases, due to the relatively limited working flow of the ejector, the opening of the pressure regulating valve can be gradually increased to meet the hydrogen demand of the fuel cell.

[0054] Theoretically, the opening of the pressure regulating valve can be adjusted from zero. However, in practical applications, the pressure regulating valve, especially the pressure regulating valve with relatively large working pressure, has relatively poor regulation accuracy near the zero value. In some embodiments, when the difference between the fuel cell stack consumption and the working flow of the ejector is greater than or equal to the minimum flow regulation value of the pressure regulating valve, the switch valve is controlled to open. Thus, when the fuel cell stack consumption continues to increase, the regulation range of the pressure regulating valve is greater than the minimum flow regulation value; when the fuel cell stack consumption continues to decrease, the switch valve is closed, and the regulation range of the pressure regulating valve can also be greater than the minimum flow regulation value. Therefore, high-precision flow regulation can be achieved. In one possible case, the minimum flow regulation value of the pressure regulating valve can match the working flow capacity of the ejector. When Q consumption>1.1Q P ~1.2Q P When the switch valve is opened, Q consumption is the fuel cell stack consumption, Q P is the working flow of the ejector. At this time, the pressure control valve needs to provide the fuel cell with no less than 0.1Q P ~0.2Q P The consumption exceeds the minimum flow value within the adjustable range of the pressure controller, ensuring the control accuracy of the pressure controller.

[0055] In some embodiments provided in the present application, the gas supply circulation system may include a controller, and the gas supply circulation system may control the opening and closing of the switch valve through the controller.

[0056] exist Figure 1In the illustrated embodiment, the gas supply circulation system may further include a gas-water separator. The gas-water separator may be connected between the fuel cell and the ejector inlet. When the switch valve is opened, the gas-water separator may separate the water-wet hydrogen discharged from the fuel cell into gas and water, and the separated hydrogen may enter the fuel cell again after being ejected and circulated by the ejector. To ensure the purity of the hydrogen, the gas-water separator periodically discharges a small amount of tail gas from the fuel cell. When the switch valve is disconnected, since the pressure regulating valve can provide excess hydrogen for the fuel cell, the unconsumed hydrogen of the fuel cell may be discharged to the atmosphere through the gas-water separator tail. In the embodiment provided in the present application, the working state of the gas-water separator may be adapted to the working state of the ejector, so that the gas supply circulation system may provide a continuous and stable supply of hydrogen for the fuel cell. In some embodiments, the working state of the gas-water separator may be regulated by a controller.

[0057] If the ejector structure is not designed properly, the ejection capacity of the ejector may be insufficient or even fail under certain working conditions. Generally speaking, when the fuel cell stack consumption is the largest, the ejector needs to provide a larger ejection flow rate. Therefore, the ejector is designed according to the working conditions corresponding to the maximum stack consumption, and the ejection capacity of the ejector usually meets the requirements. However, this is not completely consistent with the actual situation.

[0058] Assume that the pressure at the ejector outlet is P c , P c The ejection coefficient of the ejector can be related to the outlet mixed pressure P c Related, can also be with P c -P h Related, where P c -P h The impact is greater. c -P h It can be used to represent the flow resistance of devices such as fuel cells and gas-water separators. Assume that P c unchanged, P c -P h The larger the value, the worse the ejector's ejection capability. Assume that P c -P h unchanged, P c The larger it is, the worse the ejector's ejection capability is.

[0059] Generally speaking, as the operating power of the battery stack increases, P c The step-by-step setting gradually increases, and the maximum value is achieved when the battery stack is running at full power. Therefore, when the battery stack consumption is at its maximum, there may be a problem of insufficient ejector capacity.

[0060] P c -P h Can satisfy:

[0061] Pc -P h =ξ 电堆 *(Q 消耗 +G h ) 2 / ρ 饱和湿氢气 +ξ 气水分离 *G h 2 / ρ 饱和湿氢气 ,

[0062] where ξ 电堆 is the flow resistance coefficient generated by the stack, ξ 气水分离 is the flow resistance coefficient produced by gas-water separation, which can be a constant; G h is the ejector flow rate (the circulation volume of the fuel cell), which should be at least not less than the circulation volume required by the fuel cell under various operating conditions; Q 消耗 is the consumption of the fuel cell under various operating conditions, which increases with the increase of operating power; ρ 饱和湿氢气 is the density of saturated wet hydrogen, and its value increases with the increase of Pc. Therefore, there is a low power condition, due to P C The value is small, so ρ 饱和湿氢气 Small. Although Q 消耗 The maximum value is when the battery stack is at full power, but ρ 饱和湿氢气 At low power, P c -P h The maximum value may occur when the stack is in low power condition. Therefore, when the stack consumption is at the minimum, the ejector capacity may be insufficient.

[0063] Since the ejection capacity of the ejector is related to P c and P c -P h Therefore, under the condition where the stack consumption is relatively large, its stack consumption is slightly less than that of the stack consumption under full power condition, but its corresponding P c -P h Greater than P corresponding to full power condition c -P h , which may cause the ejector capacity to be insufficient under conditions where the stack consumption is relatively large (not maximum).

[0064] Since the ejection capacity of the ejector is related to P c and P c -P h Therefore, under the condition where the stack consumption is relatively small, its stack consumption is slightly greater than that of the stack under the lowest power condition, but its corresponding P c -P h Greater than the P corresponding to the minimum power condition c -P h, which may cause the ejector capacity to be insufficient under the operating conditions where the stack consumption is relatively small (not minimum).

[0065] In summary, when the stack consumption is at the maximum, minimum, larger, or smaller, the ejector capacity may be insufficient. How to make the ejection capacity of the designed ejector meet all the required working conditions and give the ejector a larger operating range is a problem that needs to be solved.

[0066] In view of the above problems, the embodiment of the present application provides a design process of an ejector. Assuming that the gas supply circulation system can work under N working conditions, the following design process can be aimed at working condition A among the N working conditions.

[0067] 1. Preset the ejector working fluid pressure P p , the ejection fluid pressure P h and ejector working flow G P =G 最小消耗 -G 压力调节阀 ; Calculate the ejector flow rate G h =Q×(i-1), Q is the fuel cell consumption under condition A, and i is the excess coefficient.

[0068] The working fluid pressure P can be calculated based on empirical values. p Perform initial setting. Ejector working pressure P p , to ensure the expansion ratio of the working fluid in the ejector (P P / P h ) is greater than the critical pressure ratio within the operating range to ensure that the nozzle throat velocity reaches no less than the critical velocity; and cannot exceed the inlet allowable pressure range of the pressure regulating valve. If the above requirements are met, the pressure can be selected at a lower value.

[0069] G 最小消耗 It is the minimum stack consumption when the gas supply circulation system opens the ejector, which corresponds to the minimum stack loading current of the fuel cell when the ejector is opened. 最小消耗 It can reflect the operating range of the ejector. 最小消耗 The larger the value, the greater the stack consumption when the ejector is turned on, which will cause gas waste caused by the need to discharge excess gas before the ejector is turned on. 压力调节阀 It is the minimum flow adjustment value of the pressure regulating valve. This value must ensure that the accuracy of the flow controlled by the pressure regulating valve meets the required minimum flow.

[0070] 2. Iteratively calculate the achievable ejection coefficient u for condition A.

[0071] 2.1, i = 1, assign u to the achievable ejection coefficient u of condition A i ;

[0072] 2.2, according to u i =G hi / G pi , calculate the ratio of working gas to ejected gas, the specific volume and gas adiabatic index of the working gas are known according to their corresponding pressure and temperature, and v is calculated according to the ratio of working gas to ejected gas ci (Specific volume of mixed gas), k ci (Gas adiabatic index after mixing); v pi (Working gas specific volume), k pi (Working gas adiabatic index) can be determined by the working fluid pressure P p Calculated, v Hi (Specific volume of ejected gas), k Hi (Injection gas adiabatic index) can be determined by the injection fluid pressure P h Calculated.

[0073] 2.3, define i=i+1;

[0074] 2.4, according to the formula, the ejection coefficient u can be calculated i :

[0075]

[0076]

[0077]

[0078]

[0079] Nozzle velocity coefficient Velocity coefficient of the mixing chamber Velocity coefficient of diffuser Velocity coefficient at the inlet section of the mixing chamber P c -P h =ξ 电堆 *(Q 消耗 +G h ) 2 / ρ 饱和湿氢气 +ξ 气水分离 *G h 2 / ρ 饱和湿氢气 ; pH is the reduced isentropic velocity of the ejected gas on a certain interface, according to П PH =p H / p p , the converted isentropic velocity can be obtained by looking up the gas dynamics function table in "Basics of Air and Gas Dynamics"; n = 1.01 ~ 1.08.

[0080] 2.5, judgement |ui -u i-1 Determine whether |≤u’ holds. u’ can be 0 or a value close to 0, such as 0.1, 0.01, etc. If it holds, determine ui as the achievable entrainment coefficient u under operating condition A; if it does not hold, perform step 2.2.

[0081] 3. Based on the u obtained in step 2, determine whether U<u holds, where U is the designed entrainment coefficient of the ejector under operating condition A, and U = G h / G P . If it holds, determine the designed entrainment coefficient U of the ejector under operating condition A, and the preset working flow rate G P and the working fluid pressure P p of the ejector in step 1 meet the design requirements. If it does not hold, adjust the working flow rate G P and / or the working fluid pressure P p until U<u holds, and finally determine the designed entrainment coefficient of the ejector under operating condition A. Without changing the working fluid pressure P p , by increasing the working flow rate G P of the ejector, the designed entrainment coefficient U of the ejector under operating condition A can be reduced. Without changing the working flow rate G P of the ejector, by increasing the working fluid pressure P p , the achievable entrainment coefficient u under operating condition A can be increased. If the working fluid pressure P P has reached the allowable pressure range at the inlet of the pressure regulating valve and U<u still does not hold, the working flow rate G P of the ejector can be increased, and the loading current corresponding to the fuel cell stack when the ejector is opened can be increased.

[0082] 4. Based on the determined designed entrainment coefficient U, design each structure of the ejector, specifically refer to Figure 3 .

[0083] 4.1 The nozzle throat diameter of the ejector

[0084] is the critical area of the nozzle throat;

[0085]

[0086] 4.2 The nozzle opening diameter d of the ejector p1

[0087] q p1 is only related to the expansion ratio (P P / P h) is related to the gas dynamics function table in "Basics of Air and Gas Dynamics". The larger the expansion ratio, the smaller qp1. In some embodiments, the minimum P in the full operating range can be used. P / P h This ensures that there will be no large losses caused by excessive gas expansion in the entire operating range.

[0088] 4.3 Diameter d3 of the ejector mixing chamber

[0089] |f p3 -f3|≤preset threshold; According to PH =p H / p p , we can get ε by looking up the gas dynamics function table in "Basics of Air and Gas Dynamics" pH ,q pH .

[0090] 4.4 Distance l between ejector nozzle and mixing chamber c

[0091] Calculate d4 = 1.55d p1 (1+u);

[0092] When d3>d4, l c = l c1 , l c1 is the length of the free stream at the nozzle outlet, j is an experimental constant;

[0093] When d3<d4, l c = l c1 +l c2 , l c2 is the length of the mixing chamber inlet section, β is the cone angle of the mixing inlet section, Figure 3 , β = γ / 2. tg is the tangent function.

[0094] 4.5 Length of ejector mixing chamber l K It is 6 to 10 times the diameter d3 of the mixing chamber.

[0095] 4.6 Injection entrance diameter d h , ejector outlet diameter d c The range is selected according to the diameter of the connected pipe. The remaining parameters can be adjusted according to the size requirements of the installed system.

[0096] In the above embodiment, the ejector designed according to the A working condition should also meet the ejection capacity requirements under other working conditions among the N working conditions. After obtaining the design ejection coefficient of the ejector under the A working condition through the above design process, it can also be used as a basis to calculate the design ejection coefficients U2…U corresponding to other working conditions among the N working conditions. N In addition, the actual ejection coefficients U'2...U' corresponding to the ejector designed based on the A working condition in the other working conditions among the N working conditions can also be determined by experimental or simulation methods. N If U2 <U’2,……,U N <U’ N , the ejector can meet the use requirements under all working conditions.

[0097] When the number of N working conditions is relatively large, verifying the N working conditions in sequence may result in excessive calculation. The embodiment of the present application provides another design process of an ejector, which can obtain an ejector that meets the use requirements of all working conditions through a single design.

[0098] Assume that the gas supply circulation system can operate under N working conditions.

[0099] 1. Preset the ejector working fluid pressure P p , ejection fluid pressure P h and ejector working flow G P =G 最小消耗 -G 压力调节阀 For details, please refer to step 1 above.

[0100] 2. Refer to step 2 above to calculate the achievable ejection coefficients u1…u for each of the N working conditions N , and from u1...u N Find the minimum value u in min , the minimum value u min The corresponding working condition is the target working condition, and the minimum value u min The target achievable ejection coefficient corresponding to the target operating condition.

[0101] 3. According to step 2, u min , judge U≤u min Is it true, where U is the design ejection coefficient of the ejector, U = G h / G P , ejection flow rate G h =Q×(i-1), Q is the maximum stack consumption under all operating conditions (i.e., the stack consumption required when the stack is running at full power), and i is the excess coefficient.

[0102] If it is established, the ejector design ejection coefficient U is determined, and the ejector working flow rate G preset in step 1 is Pand working fluid pressure P p Meet the design requirements. If not, then adjust the ejector working flow G P and / or working fluid pressure P p , until U≤u min The specific implementation method can refer to step 3 above.

[0103] 4. Design the various structures of the ejector according to the determined design ejection coefficient U. The specific implementation method can refer to step 4 above.

[0104] Through the second design method provided in this application, the ejection capacity of all working conditions can be compared to ensure that the ejection coefficient within the full operating range is greater than the design value, and that there will be no compression ratio (P c / P h ) is too high, which may lead to the problem that the ejection coefficient is reduced or even negative. p Can be constant.

[0105] For an ejector of a fixed size, when it operates at the design operating point, it can ensure that the ejection flow rate meets the stack hydrogen circulation volume demand. When deviating from the design operating condition, due to the constant working flow rate, the ejection coefficient that can be achieved is greater than the design operating point. According to the ejector calculation characteristic curve, the achievable ejection coefficient can be higher than the design operating point. Since it is not the optimal design size, the ejector increases in the range of deviation from the design operating condition, and the loss will increase, resulting in the actual achievable ejection coefficient deviating greatly from the calculated ejection coefficient, but it can still be higher than the actual achievable ejection coefficient of the design operating point, ensuring that the ejection flow rate is not less than the design operating point when operating under other operating conditions. The ejector designed by the second design method provided in the present application can have a better ejection capacity.

[0106] Although the present application is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

Claims

1. An ejector, characterized in that: The ejector is applied to a gas supply circulation system, and the gas supply circulation system comprises: Fuel cells; a target gas source, for supplying a target gas to the fuel cell; A pressure regulating valve and an ejector, wherein the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source; The ejector comprises a working inlet, an ejector inlet and an ejector outlet, wherein the working inlet is connected to the target gas source, the target gas discharged from the fuel cell enters the ejector through the ejector inlet, and is mixed with the target gas input from the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet; The ejector is applied to N working conditions, and the ejector satisfies: Under the target operating condition among the N operating conditions, the design ejection coefficient of the ejector is less than the achievable ejection coefficient corresponding to the target operating condition, Under other working conditions among the N working conditions, the actual ejection coefficient of the ejector in the working condition is not less than the design ejection coefficient corresponding to the ejector in the working condition; The designed ejection coefficient U=G h / G P , the ejection flow rate G of the ejector h =Q×(i-1), the ejector working flow G P =G 最小消耗 -G 压力调节阀 , Q is the maximum stack consumption or the stack consumption under the working condition corresponding to the design ejection coefficient, i is the excess coefficient, G 最小消耗 The minimum stack consumption when the gas supply circulation system opens the ejector, G 压力调节阀 is the minimum flow rate adjustment value of the pressure regulating valve; the achievable ejection coefficient u satisfies: Nozzle velocity coefficient Velocity coefficient of the mixing chamber Velocity coefficient of diffuser Velocity coefficient at the inlet section of the mixing chamber Δp c =P c -P h ; P c -P h =ξ 电堆 *(Q 消耗 +G h ) 2 / r 饱和湿氢气 +ξ 气水分离 *G h 2 / r 饱和湿氢气 ; ξ 电堆 is the flow resistance coefficient generated by the battery stack, Q 消耗 is the consumption of the fuel cell under various working conditions, G h is the ejector flow rate, ρ 饱和湿氢气 is the density of saturated wet hydrogen, ξ 气水分离 is the flow resistance coefficient produced by gas-water separation; υ p is the specific volume of the working gas; H is the specific volume of the ejected gas; c is the specific volume of the mixed gas; p p is the working gas pressure; P h is the ejection gas pressure; P c is the pressure of the mixed gas; k p is the working gas adiabatic index; k H is the adiabatic index of the ejected gas; k c is the adiabatic index of the mixed gas; pH is the converted isentropic velocity; n = 1.01 ~ 1.

08.

2. The ejector according to claim 1, characterized in that: The N operating conditions correspond one-to-one to N achievable injection coefficients, and the achievable injection coefficient corresponding to the target operating condition is the minimum value of the N achievable injection coefficients.

3. The ejector according to claim 1 or 2, characterized in that: When the stack consumption is the largest, the working gas pressure p of the ejector is p and the ejected gas pressure P h satisfy: The expansion ratio p of the working gas in the ejector p / P h Greater than the critical pressure ratio.

4. The ejector according to claim 1 or 2, characterized in that: The nozzle throat diameter of the ejector is the critical area of ​​the nozzle throat; G P is the ejector working flow rate; k p is the working gas adiabatic index; p p is the working gas pressure; v p is the specific volume of the working gas.

5. The ejector according to claim 4, characterized in that: The nozzle opening diameter of the ejector f p1 =f p* / q p1 ,q p1 According to the expansion ratio p in the N working conditions p / P h The minimum value in the equation is obtained by looking up the gas dynamics function table in "Basics of Air and Gas Dynamics", P h is the ejection gas pressure.

6. The ejector according to claim 5, characterized in that: d3 is the diameter of the ejector mixing chamber, d4 = 1.55d p1 (1+u), u is the achievable ejection coefficient, and the distance between the ejector nozzle and the mixing chamber is l c satisfy: When d3>d4, l c = l c1 , l c1 is the length of the free stream at the nozzle outlet, j is an experimental constant; When d3<d4, l c = l c1 +l c2 , l c2 is the length of the mixing chamber inlet section, and β is the cone angle of the mixing inlet section.

7. The ejector according to claim 6, characterized in that: The length l of the ejector mixing chamber K It is 6 to 10 times the diameter d3 of the mixing chamber.

8. A gas supply circulation system, characterized in that: The gas supply circulation system comprises: Fuel cells; a target gas source, for supplying a target gas to the fuel cell; A pressure regulating valve and an ejector according to any one of claims 1 to 7, wherein the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source; The ejector includes a working inlet, an ejector inlet and an ejector outlet. The working inlet is connected to the target gas source. The target gas discharged from the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input from the working inlet. The mixed target gas is output to the fuel cell through the ejector outlet.

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