Method for determining a flow-related parameter

Abstract

The invention relates to a method for determining a flow-related parameter (V_dot, n_dot) in an anode path (10) of a fuel cell system (100), in particular of a solid oxide fuel cell system (100), the fuel cell system (100) comprising: - an anode path (10) having an anode path inlet (11), the anode path inlet (11) being configured for feeding a fuel gas into the anode path (10); - an anode (16) having an anode inlet (15) and an anode outlet (17), the anode inlet (15) being connected to the anode path inlet (11); - a lambda sensor (50) which is arranged in the anode path (10) and is configured for measuring a lambda value (λ) in the anode path (10), the method having the steps of - measuring (110), by means of the lambda sensor (50) in the anode path (10), a current (I_mess) or a voltage (U_mess) which is indicative of a lambda value (λ) in the anode path (10), and - calculating (130), in particular by means of a control unit (FCCU), a flow-related parameter (V_dot, n_dot) of the fuel gas in the anode path (10) depending on the current (I_mess) or the voltage (U_mess).

Description

[0001] Description

[0002] title

[0003] Method for determining a fluidic parameter

[0004] The invention relates to a method having the features of the independent method claim, a fuel cell system having the features of the independent device claim, a computer program product having the features of the independent patent claim relating to a computer program product, a computer-readable data carrier having the features of the independent patent claim relating to a computer-readable data carrier, a control unit having the features of the independent patent claim relating to a control unit, and a system having the features of the independent patent claim relating to a system.

[0005] Fuel cell systems, in particular solid oxide fuel cells, are known, comprising at least one fuel cell unit having an anode and a cathode, as well as an electrolyte located therebetween. A fuel gas, for example natural gas, in particular comprising hydrogen (e.g., ammonia), can be supplied from the anode, and another substance comprising oxygen, e.g., air, can be supplied from the cathode. The anode and cathode can be gas-permeable. The electrolyte represents an interface at which (separate) reduction and oxidation of a redox reaction take place. The redox reaction can comprise a reaction of oxygen with the fuel gas, e.g., hydrogen. There may be an excess of oxygen on the cathode side, while there may be a deficiency of oxygen on the anode side, since the oxygen reacts directly with hydrogen there. Due to the resulting concentration gradient,

[0006] Oxygen flows from the cathode to the anode. Since the electrolyte in between is only permeable to oxygen ions, the oxygen absorbs electrons there. The resulting oxygen ions react with hydrogen ions on the anode side, which release electrons. During the exothermic reaction, the electron flow between the anode and cathode can be used externally as electrical power (current and / or voltage). Furthermore, fuel cell systems can comprise a stack of the fuel cell units described above.

[0007] The state of the art has disadvantages. For example, the volume flow and / or molar flow of the fuel gas in the anode path may not be known or may not be known precisely. Furthermore, the oxygen and / or hydrogen content may not be known or may not be known precisely. Existing assumptions and / or measurements may either be missing or in need of improvement. Furthermore, known processes and / or fuel cell systems may be too complicated and / or too costly. Furthermore, the control and / or regulation may be inadequate.

[0008] It is therefore an object of the present invention to at least partially overcome at least one of the disadvantages described above. In particular, the object of the invention is to provide an improved and / or more accurate method and / or fuel cell system, and in particular to determine the lambda value in the anode path. A lambda value can comprise a fuel-to-air ratio or combustion air ratio.

[0009] The above object is achieved by a method having the features of the independent method claim, a fuel cell system having the features of the independent device claim, a computer program product having the features of the independent patent claim relating to a computer program product, a computer-readable data carrier having the features of the independent patent claim relating to a computer-readable data carrier, a control unit having the features of the independent patent claim relating to a control unit, and a system having the features of the independent patent claim relating to a system. Further features and details of the invention emerge from the subclaims, the description, and the drawings.Features and details described in connection with the method according to the invention naturally also apply in connection with the fuel cell system according to the invention and / or in connection with the computer program product according to the invention and / or in connection with the computer-readable data carrier according to the invention and / or in connection with the control unit according to the invention and / or in connection with the system according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made to each other. In particular, advantages described in the context of the first, second, third, fourth, fifth and / or sixth aspect also apply to the first, second, third, fourth, fifth and / or sixth aspect.

[0010] The above object is achieved according to a first aspect by a method for determining a fluidic parameter in an anode path of a fuel cell system, in particular a solid oxide fuel cell system, the fuel cell system comprising

[0011] - an anode path with an anode path inlet, wherein the anode path inlet is arranged for feeding a fuel gas into the anode path,

[0012] - an anode having an anode input and an anode output, the anode input being connected to the anode path input,

[0013] - a lambda sensor which is arranged in the anode path and is configured to measure a lambda value in the anode path, the method comprising

[0014] - Measuring, by the lambda sensor in the anode path, a current or a voltage which is specific for a lambda value in the anode path,

[0015] - Calculating, in particular by a control unit, a flow parameter of the fuel gas in the anode path as a function of the current or voltage.

[0016] The method can be computer-implemented. The described actions or features of the method can be performed in the order shown, and in particular can be performed repeatedly. The method can preferably be used to control and / or regulate a fuel cell system according to the second aspect. Particularly preferably, a control unit according to the fifth aspect can be used for calculating, transmitting, operating, controlling, and / or regulating. The control unit can perform the corresponding actions or features and / or perform a control operation, preferably to implement the actions.

[0017] Fuel gas can preferably comprise natural gas. Natural gas can be used in a fuel cell system in different concentrations and / or compositions. Accordingly, determining the composition and / or calculating a flow parameter can be particularly advantageous and, in particular, have a particularly advantageous effect on the operation of the fuel cell system. Alternatively, however, other fuels or fuel gases can also be used. The fuel gas or the material flow in the anode path can at least partially comprise (recirculated) fuel gas or exhaust gas from the anode outlet. This can be recirculated via a recirculation unit (see below).

[0018] It can be provided that calculating the fluidic parameter makes it possible to omit a (different) sensor for determining the fluidic parameter and / or to enable redundancy or control. Thus, an (in)direct determination or calculation of the fluidic parameter can be enabled.

[0019] Within the scope of the invention, it may be advantageous for the fluidic parameter to comprise a volume flow and / or a molar flow of the fuel gas.

[0020] For example, the volume flow can be a volume per unit of time, e.g., [nl / s] (standard liters per second). Accordingly, a flow parameter in the anode path can be calculated based on the measurement.

[0021] Within the scope of the invention, it is conceivable that a transmission of the current or voltage determined by the measurement from the lambda sensor to a control unit, in particular to a computing unit of the control unit, is carried out, in particular after the measurement and / or before the calculation.

[0022] It can be provided within the scope of the invention that the current and / or the voltage are specific for a heating current and / or a heating voltage which is applied by the lambda sensor and / or by the control unit to a resistor of the lambda sensor in order to compensate for cooling of the lambda sensor, electrolyte and / or resistor, in particular during measurement, by the fuel gas.

[0023] It can be provided that the lambda sensor is kept at a certain temperature, e.g. by a heating element. A resistance of an electrolyte in the lambda sensor can be measured. In the context of the invention, the resistance can mean the electrolyte or the (physical) resistance of the electrolyte. If the resistance changes, e.g. drops / increases too sharply, the heating element can increase a heating current and / or a heating voltage. This allows the temperature to be controlled and / or regulated. The temperature can therefore preferably be kept constant. For example, it can be provided that the temperature is to be kept at T = 800°C, in particular by controlling and / or regulating. The lambda sensor can be cooled by the fuel gas, which can in particular have a lower temperature. Accordingly, it can be provided that the heating current is increased as a function of the cooling.Thus, it can be provided that the fluidic parameter, for example the volume flow (cf. Fig. 3 as an example), can be determined as a function of the heating current and / or the heating voltage. Alternatively or additionally, it can be provided that an impedance of the electrolyte or the resistance is measured. The electrolyte, in particular of the Nernst cell, can comprise ZrO2, for example. This can be advantageous, since larger signal changes can occur than with a resistance. This can improve measurement accuracy. It can be provided that the lambda sensor is designed as a step lambda sensor and / or broadband lambda probe. Furthermore, it can be provided, in particular during operation, that a variation / adjustment of the heating voltage and / or the heating current is carried out as a function of the temperature of the combustion gas.For example, in standard operation, the heating voltage can be 12V, which in particular results in a lambda sensor temperature of approximately 800°C. It can be provided, particularly under the condition that the sensor temperature is always greater than the temperature of the combustion gas, to also reduce the heating voltage and / or the heating current, and preferably thereby increase the sensitivity and / or accuracy, e.g. because a highly sensitive heating voltage or heating current is enabled for calculating the volume flow. It can be provided that (for this purpose) the sensor temperature is measured, for example by the lambda sensor and / or a temperature sensor.

[0024] It is further conceivable that the measuring comprises measuring a temperature of the combustion gas by the lambda sensor and / or a temperature sensor in the anode path, wherein the calculation is preferably carried out as a function of the temperature of the combustion gas.

[0025] It can be provided that the lambda sensor is configured to measure the temperature of the combustion gas. Alternatively or additionally, a temperature sensor can be provided. It can be provided that the fluidic parameter, in particular the volume flow, can be determined as a function of the heating current and / or the heating voltage and / or the temperature of the combustion gas. It can also be provided that (additionally) the fluidic parameter, in particular the volume flow, can be determined as a function of the hydrogen content (see below). Cooling by the combustion gas (see above) can take place as a function of the temperature of the combustion gas. Accordingly, it can advantageously be provided to determine the temperature of the combustion gas. The temperature sensor can be arranged in or on the lambda sensor. This can enable a compact design and / or precise measurement of the temperature of the combustion gas.Alternatively, it can be provided that a (separate) temperature sensor is provided in the anode path, wherein this can preferably be arranged close to the lambda sensor. This can enable a simpler and / or less complex design. It can be provided that calibration is carried out during the development and / or commissioning of the fuel cell system. One or different fuel gases, in particular natural gas (which varies individually depending on location and / or time) in different compositions, e.g. G222, G21, G23, can be used to determine the heating current and / or the heating voltage as a function of a (measured) volume flow. Alternatively or additionally, the temperature of the fuel gas can be varied. This makes it possible to calculate a calibration in each case, e.g. by the control unit. This can be stored in the control unit, in particular a memory unit of the control unit.During (normal) operation of the fuel cell system, a fluidic parameter, such as the volume flow, can be determined as a function of the heating current, for example via the (stored) calibration.

[0026] It is also conceivable that the measuring comprises measuring a hydrogen content of the fuel gas by the lambda sensor and / or a hydrogen content sensor in the anode path, wherein the calculation is preferably carried out as a function of the hydrogen content of the fuel gas.

[0027] It can be provided that the lambda sensor is configured to measure the hydrogen content of the fuel gas. For example, it can be provided to determine the hydrogen content via / as a function of a pumping current of the (broadband) lambda sensor. This is advantageously (at least partially) independent of the heating current / heating voltage. Accordingly, one lambda sensor can be sufficient. Alternatively or additionally, a hydrogen content sensor can be provided which is configured for this purpose. It can be provided that the fluidic parameter, in particular the volume flow, can be determined as a function of the heating current and / or the heating voltage and / or the temperature of the fuel gas and / or the hydrogen content of the fuel gas. It can preferably also be provided that (additionally) the fluidic parameter, in particular the volume flow, can be determined as a function of the hydrogen content.Cooling by the fuel gas or the (required) heating current / heating voltage (see above) can be dependent on the temperature and / or the hydrogen content of the fuel gas. Accordingly, it can advantageously be provided to determine the hydrogen content of the fuel gas. The hydrogen content sensor can be arranged in or on the lambda sensor. This can enable a compact design and / or precise measurement of the temperature of the fuel gas. Alternatively, it can be provided that a (separate) hydrogen content sensor is provided in the anode path, whereby this can preferably be arranged near the lambda sensor. This can enable a simpler and / or less complex design. It can be provided that calibration is carried out as part of the development and / or commissioning of the fuel cell system.One or different fuel gases, in particular natural gas in different compositions, e.g. G222, G21, G23, can be used to determine the heating current and / or the heating voltage as a function of a (measured) volume flow. In addition, the temperature can be determined. In this way, a calibration can be calculated in each case, e.g. by the control unit. This can be stored in the control unit, in particular a memory unit of the control unit. During (normal) operation of the fuel cell system, a fluidic parameter, such as the volume flow, can be determined as a function of the heating current, for example via the (stored) calibration. The calibration can be determined, for example, by fitting, in particular a polynomial, e.g. of the fourth degree. For example, the following equation can be used for calibration:

[0028] V_dot = xl * IJieiz 3+ x2 * IJieiz 2 + %3 * IJieiz + x4

[0029] Here, x1, x2, x3, and / or x4 are coefficients, l_heat is the heating current, and V_dot is the volume flow. The coefficients can be determined empirically, particularly during commissioning, and / or by simulation. The (anode) temperature and / or the hydrogen content can be varied.

[0030] It may also be provided to use another gas property (instead of the hydrogen content) alternatively or additionally, for example, the hydrogen-carbon ratio (H / C) and / or the CH4 content. Accordingly, it may be provided that the coefficients, e.g., of the polynomial, are determined depending on this gas property.

[0031] To achieve (further) improvement of the method with the goal of greater accuracy, the method can be combined with a machine learning method. The machine learning method can be used in particular to estimate the (already small) error between the actual / real value for the fluidic parameter and the value determined by calculation for the fluidic parameter, and thus advantageously improve the latter values. For this purpose, a machine learning algorithm can be trained in advance with training data for estimating the error, particularly at various operating points, for example during commissioning. The machine learning method can be implemented as a function of the measured variables of the lambda sensors such as heating current, heating voltage, pumping current, pumping voltage, temperature and / or Nernst voltage, as well as other variables (temperatures, pressures, volume flows, etc.).) from the fuel cell system in which the lambda sensor is used. The error can then represent the output variable. For example, in addition to multivariate linear regression, a neural network, and in particular the application of a Gaussian process, can be used.

[0032] Within the scope of the invention, it is optionally possible for the fuel cell system to be operated by the control unit as a function of the calculation and / or the flow parameters of the fuel gas, in particular after the calculation.

[0033] In this case, operation can in particular comprise controlling and / or regulating, wherein preferably a control unit (see below) is used. For example, the supply of fuel gas can be adjusted, e.g., via a fuel gas valve. Accordingly, the (improved and / or more accurate) calculation of a fluidic parameter, e.g., the volume flow and / or the molar flow, can advantageously lead to more precise and / or more efficient operation. This can, for example, improve the efficiency of the fuel cell system. The above object is further achieved according to a second aspect by a fuel cell system according to the invention, in particular a solid oxide fuel cell system, which is configured to determine a fluidic parameter in an anode path of the fuel cell system, comprising

[0034] - an anode path with an anode path inlet, wherein the anode path inlet is arranged for feeding a fuel gas, in particular natural gas, hydrogen and / or NH4, into the anode path,

[0035] - an anode having an anode input and an anode output, the anode input being connected to the anode path input,

[0036] - a lambda sensor arranged in the anode path and configured to measure a lambda value in the anode path.

[0037] The fuel cell system can preferably have a control unit according to the fifth aspect. The fuel cell system and / or the control unit is preferably configured to implement the method according to the first aspect.

[0038] The fuel cell unit can comprise one or more fuel cells, which can be arranged in a stack (e.g., a "stack"). Each fuel cell can comprise an anode and / or a cathode, wherein, in particular, the anode can be connected to the anode path and / or the cathode can be connected to a cathode path. An electrolyte can be arranged between the anode and the cathode. The fuel cell unit(s) can preferably comprise solid oxide fuel cells.

[0039] The fuel cell system or fuel cell unit can be used to generate energy, in particular by generating thermal and / or electrical energy or power. Thus, a current and / or voltage can be utilized, for example, for external devices. The fuel cell system preferably comprises an inverter, in particular a DC / AC converter. This can preferably be tapped via an anode electrode connected to the anode and a cathode electrode connected to the cathode.

[0040] The anode path can carry a material flow and / or the fuel gas, in particular to an anode inlet (see below). The anode path can also comprise, at least in part, a material flow and / or a fuel gas from the anode outlet. In other words, for example, natural gas (as fuel gas) can be introduced into the anode path inlet and guided into the anode via the anode inlet. At least in part, the fuel gas or exhaust gas is discharged again from the anode outlet. The anode path can comprise a recirculation unit. The fuel gas can be (at least in part) recirculated through the recirculation unit, preferably from the anode outlet to a recirculation connection point. Accordingly, in addition to the original fuel gas (e.g. natural gas), recirculated fuel gas (or exhaust gas) can also be included between the recirculation connection point and the anode inlet.The recirculation connection point can preferably be arranged downstream of the anode inlet. The recirculation connection point can be arranged between an anode path preheater and a reformer. The reformer can be connected to the anode inlet. The anode path preheater can be connected to a desulfurizer. The desulfurizer can be connected to the anode path inlet. It can be provided that an evaporator is connected between the desulfurizer and the anode path preheater, which evaporator can be configured in particular to supply water and / or steam. The fuel gas / natural gas can be introduced into the anode path inlet, for example, via a tank and / or via a fuel gas valve. During operation, the fuel gas valve can be adjusted by the control unit, e.g., by a control signal to a corresponding actuator.

[0041] It can be provided that the anode outlet and / or cathode outlet are connected to a burner. It can be provided that the fuel gas or exhaust gas is at least partially fed to the burner. This can be combusted, in particular partially, by the burner. In particular, air, oxygen, ammonia and / or (flammable) chemical compounds, in particular comprising hydrogen, can be combusted. The burner can be connected to a waste heat exchanger, which can, for example, utilize residual heat. The waste heat exchanger, the anode path preheater, the cathode path preheater and / or the evaporator can be connected to a heating unit, which can, for example, be configured as a heat reservoir.

[0042] The anode inlet can be designed to receive the fuel gas supplied in the anode path and, in particular, to guide it into the interior of the fuel cell unit.

[0043] The anode outlet can be configured to discharge the fuel gas or the products from the anode C, "exhaust gas"), and in particular from the interior of the fuel cell unit. Water, in particular water vapor, can also be discharged at least in part. Within the scope of the invention, it can be provided to refer to the returned portion of the anode outlet or the recirculation unit (simply) as fuel gas.

[0044] The cathode path can guide a material flow, in particular towards a cathode inlet (see below), preferably via a cathode path preheater.

[0045] The cathode inlet can be configured to receive a cathode input current, and in particular to lead it into the interior of the fuel cell unit. The cathode input current can preferably comprise oxygen and / or air.

[0046] The cathode output may be configured to output a cathode output current, and in particular may lead from the interior of the fuel cell unit.

[0047] The fuel cell unit can comprise an electrolyte, particularly in the form of a membrane, along the sides of which the cathode path and the anode path, or the corresponding material flows, are routed, preferably to enable an (exothermic) redox reaction. Unless otherwise stated, transport between different components of the fuel cell unit can be achieved through connecting units, such as pipes. This can enable a material flow for operating the fuel cell system.

[0048] The recirculation unit can be included in the anode path, in particular form part of the anode path.

[0049] Furthermore, within the scope of the invention, it can be provided that the fuel cell system has at least one of the following features:

[0050] - a control unit, in particular as a logic circuit, wherein the control unit is configured to carry out and / or control / regulate a method according to the first aspect, in particular at least partially,

[0051] - an inverter, in particular a DC / AC converter.

[0052] This results in the same advantages with regard to a fuel cell system according to the invention as have already been described with regard to a method according to the invention according to the first aspect.

[0053] Furthermore, it can be provided within the scope of the invention that the lambda sensor is arranged in the anode path:

[0054] - at the anode input,

[0055] - at the anode output,

[0056] - in a recirculation unit which connects the anode outlet to the anode inlet, in particular at a recirculation connection point, preferably for exhaust gas recirculation, and / or

[0057] - upstream of a reformer in the anode path of the fuel cell system, in particular between a recirculation connection point and the reformer.

[0058] The lambda sensor can be arranged in and / or on the anode path, in particular with the features above. The lambda sensor can also be connected via a connector, in particular as a dead end. The lambda sensor can preferably be configured for (electrochemical) determination of the lambda value and / or the oxygen content or oxygen excess / oxygen deficiency of the combustion gas. The lambda sensor can preferably be configured for broadband operation or have a broadband lambda sensor. With broadband lambda sensors, the oxygen excess or deficiency can be measured in relation to a stoichiometric composition in the combustion gas. The usual measuring range can be, for example, = 0.4 to 1.3.For example, for X < 1 in a not fully reformed, partially oxidized CHO gas (CHO gas: gas mixture whose molecules contain (exclusively) C, H and O atoms), as is present, for example, at the anode inlet of a solid oxide fuel cell system:.

[0059] The (broadband) lambda sensor can enable a combination of potentiometric and amperometric measurement methods. A Nernst cell and a pump cell can be connected in series, with a measuring chamber for the fuel gas provided between the two cell variants. A ceramic diffusion barrier with defined, known (diffusion) properties is preferably located between the measuring chamber and the fuel gas. Using a heating element, the sensor can be kept at a constant temperature (e.g., 800°C), which, in particular, eliminates any influence of temperature on the sensor signal (pumping current). Furthermore, the (broadband) lambda sensor can exhibit high signal dynamics with response times of less than 100 ms. The voltage signal of the Nernst cell can have a constant value, e.g., due to the different oxygen partial pressures in the measuring chamber and / or the ambient air as a reference gas.of 450 mV (thus X = 1 can apply in the measuring chamber). For this purpose, oxygen can be pumped into or out of the measuring chamber, particularly depending on the air-fuel gas mixture. The pumping current required for this is proportional to the mass flow of oxygen. It can be provided that, particularly in the case of rich exhaust gas, as can be present at the anode inlet and / or anode outlet, oxygen is pumped from the pump cell, in particular an exhaust gas electrode of the pump cell, into the measuring chamber. For this purpose, oxygen can be generated by the reduction of H2O and CO2 at the exhaust gas electrode. In the measuring chamber, the oxygen then preferably reacts with the diffused-in fuel gas or

[0060] Exhaust gas components and the reaction products (H2O and CO2) diffuse back out through the diffusion barrier.

[0061] With regard to the present invention, it is conceivable that the lambda sensor is configured to measure a current or a voltage, wherein the current and / or the voltage are specific to a heating current and / or a heating voltage applied by the lambda sensor and / or by the control unit to a resistor of the lambda sensor in order to compensate for cooling of the resistor, in particular during measurement by the (colder) fuel gas.

[0062] The above object is further achieved according to a third aspect by a computer program product according to the invention, comprising instructions which, when the computer program product is executed by a computer, cause the computer to implement the method according to the first aspect.

[0063] This results in the same advantages with regard to a computer program product according to the invention as have already been described with regard to a method according to the invention according to the first aspect and / or a fuel cell system according to the invention according to the second aspect.

[0064] The above object is further achieved according to a fourth aspect by a computer-readable data carrier according to the invention, in which instructions are stored which, when executed by a computer, cause the computer to carry out the method according to the first aspect.

[0065] This results in the same advantages with regard to a computer-readable data carrier according to the invention as have already been described with regard to a method according to the invention according to the first aspect and / or a fuel cell system according to the invention according to the second aspect and / or a computer program product according to the invention according to the third aspect.

[0066] The above object is further achieved according to a fifth aspect by a control unit according to the invention, comprising a computing unit and a memory unit in which instructions are stored which, when at least partially executed by the computing unit, carry out a method according to one of the preceding claims.

[0067] It can be provided that the control unit, in particular the computing unit, carries out and / or initiates the method steps, for example by controlling the lambda sensor, temperature sensor, hydrogen content sensor, fuel cell system and / or its (above) components. The control unit can send control signals to corresponding actuators of the fuel cell system in order to adjust them. The control unit can also receive sensor signals from sensors of the fuel cell system, for example the lambda sensor, which are taken into account in particular during calculation, operation, control and / or regulation. Based on this, for example, target values ​​can be calculated, in particular a target temperature or target efficiency. In other words, an operating point can be set by the control unit, in particular depending on a calculation.

[0068] The control unit can carry out the method at least partially and / or control and / or regulate the fuel cell system in order to carry out the method at least partially.

[0069] The control unit can be included in the fuel cell system and / or connected to it, for example via a data connection.

[0070] In this case, the control unit can be connected, in particular for controlling and / or regulating, to the lambda sensor, in particular the heating element, temperature sensor, hydrogen content sensor, burner, evaporator, anode path preheater, fuel cell unit, cathode path preheater, and / or fuel gas valve, preferably via a data connection. The aforementioned components can each have an actuator which can be controlled by the control unit, for example for adjusting a valve, controlling a sensor, and / or transmitting data (e.g. recorded sensor data). Furthermore, the aforementioned components can each have a sensor which is designed to record temperature, pressure, volume flow and / or other relevant parameters. The recorded results can be passed to the control unit, in particular via a data connection, in order to preferablyTaxes and / or rules, especially calculations, must be taken into account.

[0071] This results in the same advantages with regard to a control unit according to the invention as have already been described with regard to a method according to the invention according to the first aspect and / or a fuel cell system according to the invention according to the second aspect and / or a computer program product according to the invention according to the third aspect and / or a computer-readable data carrier according to the invention according to the fourth aspect.

[0072] The above object is further achieved by a system according to the invention comprising a fuel cell system according to the second aspect and / or a control unit according to the fifth aspect.

[0073] A system can comprise a (residential) building, an industrial building, a power plant, a storage facility, a vehicle (e.g., a motor vehicle), a ship, an aircraft, or another system with, in particular, an increased energy requirement. It may be particularly preferred to provide a (essentially) stationary or non-stationary application (immobile or mobile) of the fuel cell system.

[0074] This results in the same advantages with regard to a system according to the invention as have already been described with regard to a method according to the invention according to the first aspect and / or a fuel cell system according to the invention according to the second aspect and / or a computer program product according to the invention according to the third aspect and / or a computer-readable data carrier according to the invention according to the fourth aspect and / or a control unit according to the invention according to the fifth aspect.

[0075] Further advantages, features, and details of the invention will become apparent from the following description, in which several embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. These schematically show:

[0076] Figure 1 a fuel cell system,

[0077] Figure 2 shows a method, and

[0078] Figure 3 shows a heating current l_heiz as a function of a volume flow V_dot.

[0079] In the following figures, identical reference numerals are used for the same technical features, even for different embodiments.

[0080] Fig. 1 shows, by way of example, a fuel cell system 100 with an anode path 10 and a cathode path 20. The anode path 10 comprises an anode path inlet 11, e.g. comprising a fuel gas tank and / or a fuel gas valve, which is configured to introduce a fuel gas, e.g. natural gas, into the anode path 10. This is guided to an anode inlet 15, in particular via a desulfurizer 12, an anode path preheater 13, a recirculation connection point 13.1 and / or a reformer 14. From the anode inlet 15, the fuel gas is guided into the anode 16 of a fuel cell unit 101, which in particular has an electrolyte 102 and a cathode 26. The fuel gas can react in the fuel cell unit 101 (at least partially) with a cathode inlet stream and / or air or oxygen.The anode 16 is connected to an anode outlet 17, via which the fuel gas and / or exhaust gas can be discharged from the anode 16, in particular into a burner 103 and / or a recirculation unit 18 of the anode path 10. The recirculation unit 18 can be connected to a recirculation connection point 13.1, in particular between the anode path preheater 13 and the reformer 14. This allows the fuel gas or exhaust gas to be (at least partially) recirculated. In the anode path 10, for example in or on the recirculation unit 18, a lambda sensor 50 can be arranged, which can in particular be configured to determine a lambda value, a resistance R50 (of an electrolyte of the lambda sensor), a heating current l_heat, a heating voltage U_heat, a (measured) current l_mess and / or a (measured) voltage U_mess, for example by measuring (110). It can also be provided that the lambda sensor 50 and / or a temperature sensor orHydrogen content sensor (not shown) is configured for measuring a temperature T_fuel gas of the fuel gas and / or a hydrogen content x_H2 and / or another gas quality parameter (e.g. H / C ratio). The lambda sensor 50 can also be connected or connected to other points on the anode path 10 (shown in dashed lines). The aforementioned measured values ​​can be transmitted, for example, via a data connection to a control unit FCCU, in particular a computing unit CU. In addition, the control unit FCCU can have a storage unit MU. The anode path can also have an evaporator 1, which can be configured for introducing water H2O and / or water vapor. The control unit FCCU or the computing unit CU can be connected to the evaporator 1, the anode path inlet 11, the anode path preheater 13, the lambda sensor 50 and / or an inverter 40.The cathode path 20 comprises a cathode path preheater 21 and a cathode inlet 25, which can conduct a cathode input current into the cathode 26. The cathode can further have a cathode outlet 27, which can be connected in particular to the burner 103. The burner 103 can be connected to a waste heat exchanger 104. The waste heat exchanger 104, the evaporator 1, the anode path preheater 13, and / or the cathode path preheater 21 can be connected to a heating unit 105, for example, for heat exchange.

[0081] Fig. 2 shows a method for determining a fluidic

[0082] Parameters V_dot, n_dot in an anode path 10 of a fuel cell system 100, in particular solid oxide fuel cell system 100, comprising the fuel cell system 100,

[0083] - an anode path 10 with an anode path inlet 11, wherein the anode path inlet 11 is arranged for feeding a fuel gas into the anode path 10,

[0084] - an anode 16 with an anode input 15 and an anode output 17, wherein the anode input 15 is connected to the anode path input 11,

[0085] - a lambda sensor 50 which is arranged in the anode path 10 and is configured to measure a lambda value in the anode path 10, comprising the method,

[0086] - Measuring 110, by the lambda sensor 50 in the anode path 10, a current l_mess or a voltage U_mess which is specific for a lambda value X in the anode path 10,

[0087] - Calculating 130, in particular by a control unit FCCU, a fluidic parameter V_dot, n_dot of the fuel gas in the anode path 10 as a function of the current l_mess or the voltage U_mess.

[0088] It can be provided that the fluidic parameter V_dot, n_dot comprises a volume flow V_dot and / or a molar flow n_dot of the fuel gas.

[0089] In addition, it is conceivable that a transmission 120 of the current l_mess or the voltage U_mess determined by the measurement 110 from the lambda sensor 50 to a control unit FCCU is carried out, in particular after the measurement 110 and / or before the calculation 130.

[0090] Furthermore, it can be provided that the current l_mess and / or the voltage U_mess are specific for a heating current l_heat and / or a heating voltage U_heat, which is applied by the lambda sensor 50, in particular by the control unit FCCU, to a resistor R50 of the lambda sensor 50 in order to compensate for cooling of the resistor R50 by the fuel gas, in particular during the measurement 110. It is conceivable that the measurement 120 comprises a measurement 121 of a temperature T_fuelgas of the fuel gas by the lambda sensor 50 and / or a temperature sensor in the anode path 10, wherein the calculation 130 is preferably carried out as a function of the temperature T_fuelgas of the fuel gas.

[0091] It can also be provided that the measuring 120 comprises a measuring 122 of a hydrogen content x_H2 and / or another gas quality parameter of the fuel gas by the lambda sensor 50 and / or a hydrogen content sensor in the anode path 10, wherein the calculation 130 is preferably carried out as a function of the hydrogen content x_H2 of the fuel gas.

[0092] Furthermore, it is possible for the fuel cell system 100 to be operated 140 by the control unit FCCU as a function of the calculation 130 and / or the flow parameter V_dot, n_dot of the fuel gas, in particular after the calculation 130.

[0093] Fig. 3 shows an example of a heating current l_heat as a function of a volume flow V_dot. A volume flow V_dot or a flow-related parameter V_dot, n_dot, can be calculated using a (measured) heating current l_heat, e.g. via the FCCU control unit. The diamonds, crosses and / or rectangles can represent measured values ​​which were measured, for example, as part of a calibration, e.g. during commissioning. It can be provided that a calibration curve K1, K2, K3 can be determined, for example by the FCCU control unit, as a function of the measured values ​​(e.g. by fitting a polynomial). The different curves K1, K2, K3 can represent or have different fuel gases. The arrow on the right can illustrate an increasing hydrogen content in the fuel gas. It can therefore be the case that there is a clear dependency between the volume flow and the heater current.For a clear classification, the hydrogen content and / or another gas quality parameter of the fuel gas can be used. This may be due to the fact that hydrogen, in particular, has a significantly different Cp value (thermal capacity) than other gases and thus also influences the heat transfer (cooling) from the fuel gas to the lambda sensor and / or its heating current for a constant sensor temperature.

[0094] List of reference symbols

[0095] I Evaporator

[0096] 10 Anode path

[0097] II Anode path input

[0098] 12 desulfurizers

[0099] 13 Anode path preheater

[0100] 13.1 Recirculation connection point

[0101] 14 reformers

[0102] 15 Anode input

[0103] 16 Anode

[0104] 17 Anode output

[0105] 18 Recirculation unit

[0106] 20 Cathode path

[0107] 21 Cathode path preheater

[0108] 25 Cathode input

[0109] 26 Cathode

[0110] 27 Cathode output

[0111] 50 Lambda sensor

[0112] 100 fuel cell system

[0113] 101 Fuel cell unit

[0114] 102 Electrolyte

[0115] 103 burners

[0116] 104 waste heat exchangers

[0117] 105 heat unit

[0118] 110 Measuring a current or voltage

[0119] 120 Transferring the current determined by the measurement

[0120] 121 Measuring a temperature of the fuel gas

[0121] 122 Measuring a hydrogen content of the fuel gas

[0122] 130 Calculating a fluid dynamic parameter

[0123] 140 Operating the fuel cell system

[0124] FCCU control unit

[0125] CU computing unit

[0126] MU storage unit R50 resistance of the lambda sensor, in particular an electrolyte

[0127] T_fuel gas temperature of the fuel gas l_mess (measured) current U_mess (measured) voltage l_heat heating current U heat heating voltage

[0128] V_dot, n_dot fluid dynamic parameters

[0129] V_dot Volume flow n_dot Molar flow x_H2 Hydrogen content Lambda value

[0130] K1 characteristic curve 1

[0131] K2 characteristic curve 2

[0132] K3 characteristic curve 3

Claims

Claims 1 . Method for determining a fluidic parameter (V_dot, n_dot) in an anode path (10) of a fuel cell system (100), in particular a solid oxide fuel cell system (100), the fuel cell system (100) comprising an anode path (10) with an anode path inlet (11), wherein the anode path inlet (11) is configured for feeding a fuel gas into the anode path (10), an anode (16) with an anode inlet (15) and an anode outlet (17), wherein the anode inlet (15) is connected to the anode path inlet (11), a lambda sensor (50) which is arranged in the anode path (10) and is configured for measuring a lambda value ( ) in the anode path (10), the method comprising, Measuring (110), by the lambda sensor (50) in the anode path (10), a current (l_mess) or a voltage (U_mess) which is specific for a lambda value (X) in the anode path (10), calculating (130), in particular by a control unit (FCCU), a flow parameter (V_dot, n_dot) of the fuel gas in the anode path (10) as a function of the current (l_mess) or the voltage (U_mess).

2. Method according to claim 1, characterized in that the fluidic parameter (V_dot, n_dot) comprises a volume flow (V_dot) and / or a molar flow (n_dot) of the fuel gas.

3. Method according to one of the preceding claims, characterized in that a transmission (120) of the current (l_mess) or the voltage (U_mess) determined by the measurement (110) from the lambda sensor (50) to a control unit (FCCU) is carried out, in particular after the measurement (110) and / or before the calculation (130).

4. Method according to one of the preceding claims, characterized in that the current (l_mess) and / or the voltage (U_mess) are specific for a heating current (l_heiz) and / or a heating voltage (U_heiz) which is applied by the lambda sensor (50), in particular by the control unit (FCCU), to a resistor (R50) of the lambda sensor (50) in order to compensate for cooling of the resistor (R50), in particular during the measurement (110), by the fuel gas.

5. Method according to one of the preceding claims, characterized in that the measuring (120) comprises a measuring (121) of a temperature (T_combustion gas) of the combustion gas by the lambda sensor (50) and / or a temperature sensor in the anode path (10), wherein preferably the calculation (130) is carried out as a function of the temperature (T_combustion gas) of the combustion gas.

6. Method according to one of the preceding claims, characterized in that the measuring (120) comprises a measuring (122) of a hydrogen content (x_H2) and / or another gas quality parameter of the fuel gas by the lambda sensor (50) and / or a hydrogen content sensor in the anode path (10), wherein the calculation (130) is preferably carried out as a function of the hydrogen content (x_H2) of the fuel gas.

7. Method according to one of the preceding claims, characterized in that operation (140) of the fuel cell system (100) by the control unit (FCCU) is carried out as a function of the calculation (130) and / or the flow parameter (V_dot, n_dot) of the fuel gas, in particular after the calculation (130).

8. Fuel cell system (100), in particular Solid oxide fuel cell system (100) which is configured to determine a fluidic parameter (V_dot, n_dot) in an anode path (10) of the fuel cell system (100), comprising an anode path (10) with an anode path inlet (11), wherein the anode path inlet (11) is configured for feeding a fuel gas, in particular natural gas, into the anode path (10), an anode (16) with an anode inlet (15) and an anode outlet (17), wherein the anode inlet (15) is connected to the anode path inlet (11), a lambda sensor (50) which is arranged in the anode path (10) and is configured to measure a lambda value ( ) in the anode path (10).

9. Fuel cell system (100) according to the preceding claim, characterized in that the lambda sensor (50) is arranged in the anode path (10): at the anode inlet (15), at the anode outlet (17), in a recirculation unit (18) which connects the anode outlet (17) to the anode inlet (15), in particular at a recirculation connection point (13.1), preferably for exhaust gas recirculation, and / or upstream of a reformer (14) in the anode path (10) of the fuel cell system (100), in particular between a recirculation connection point (13.1) and the reformer (14).

10. Fuel cell system (100) according to one of the preceding claims 8 or 9, characterized in that the lambda sensor (50) is designed to measure (110) a current (l_mess) or a voltage (U_mess), wherein the current (l_mess) and / or the voltage (U_mess) are specific for a heating current (l_heat) and / or a heating voltage (U_heat) which is applied by the lambda sensor (50), in particular by the control unit (FCCU), to a resistor (R50) of the lambda sensor (50) in order to compensate for cooling of the resistor (R50), in particular during the measurement (110), by the fuel gas.

11. A computer program product comprising instructions which, when executed by a computer, cause the computer to implement the method according to any one of the preceding claims 1 to 7.

12. A computer-readable data carrier in which instructions are stored which, when executed by a computer, cause the computer to carry out the method according to one of the preceding claims 1 to 7.

13. Control unit (FCCU), comprising a computing unit (CU) and a Memory unit (MU) in which instructions are stored which, when at least partially executed by the computing unit (CU), carry out a method according to one of the preceding claims 1 to 7.

14. System comprising a fuel cell system (100) according to one of the preceding claims 8 to 10 and / or a control unit (FCCU) according to the preceding claim.

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