Electrochemical system, and method for operating an electrochemical system

Abstract

The invention relates to a method for operating an electrochemical system (10) which comprises at least one electrochemical cell unit (12), a cathode-side reactant supply (14) to the electrochemical cell unit (12), and at least one anode-side reactant supply (16) to the electrochemical cell unit (12), wherein, in at least one method step, a cathode-side feed rate of the cathode-side reactant supply (14) is adjusted, and wherein, in at least one method step, an anode-side feed rate of the anode-side reactant supply (16) is adjusted. According to the invention, the cathode-side feed rate and the anode-side feed rate are determined in at least one common determination step.

Description

[0001] R.414130

[0002] - 1 -

[0003] Description

[0004] Electrochemical system and method for operating an electrochemical system

[0005] State of the art

[0006] A method for operating an electrochemical system has already been proposed, comprising at least one electrochemical cell unit, a cathode-side reactant supply to the electrochemical cell unit, and at least one anode-side reactant supply to the electrochemical cell unit, wherein in at least one process step a cathode-side feed rate of the cathode-side reactant supply is set, and wherein in at least one process step an anode-side feed rate of the anode-side reactant supply is set.

[0007] Disclosure of the invention

[0008] The invention relates to a method for operating an electrochemical system comprising at least one electrochemical cell unit, a cathode-side reactant supply to the electrochemical cell unit, and at least one anode-side reactant supply to the electrochemical cell unit, wherein in at least one process step a cathode-side feed rate of the cathode-side reactant supply is set, and wherein in at least one process step an anode-side feed rate of the anode-side reactant supply is set.

[0009] It is proposed that the cathode-side feed rate and the anode-side feed rate be determined in at least one common determination step. The electrochemical cell unit preferably comprises at least one R.414130

[0010] - 2 -

[0011] An electrochemical cell designed for the electrochemical conversion of at least one reactant to at least one product. The at least one electrochemical cell preferably comprises at least one anode, at least one cathode, and at least one gas-tight electrolyte between them, which may be oxygen-conducting and / or proton-conducting. The at least one electrochemical cell is preferably designed as a fuel cell or as an electrolysis cell. The cathode-side reactant supply is fluidically connected to the cathode and is designed to supply the cathode with a cathode-side reactant. The anode-side reactant supply is fluidically connected to the anode and is designed to supply the anode with an anode-side reactant. The cathode-side reactant and the anode-side reactant may be identical or different.The electrochemical cell unit preferably comprises a plurality, in particular at least 100, of identical electrochemical cells, which are preferably connected in parallel in terms of fluid technology and in series electrically for common operation.

[0012] The cathode-side reactant supply preferably comprises at least one fluid delivery unit, in particular a compressor, a blower, or a pump, for transporting the cathode-side reactant to the electrochemical cell unit. The cathode-side fluid delivery unit preferably regulates the cathode-side feed rate. Alternatively, the cathode-side reactant supply includes a control valve for adjusting the cathode-side feed rate. The anode-side reactant supply preferably comprises at least one fluid delivery unit, in particular a compressor, a blower, or a pump, for transporting the anode-side reactant to the electrochemical cell unit. The anode-side fluid delivery unit preferably regulates the anode-side feed rate. Alternatively, the anode-side reactant supply includes a control valve for adjusting the anode-side feed rate.

[0013] The electrochemical system preferably comprises a control unit, which preferably performs the common determination step. A "control unit" is understood to be, in particular, a cell unit with at least one control electronics unit. A "control electronics unit" is understood to be, in particular, a cell unit with a processor unit and with an R.414130

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[0015] The term "control unit" is understood to refer to a storage unit and an operating program stored within it. Preferably, the control unit determines a setpoint or manipulated value for the anode-side feed rate and transmits this value to the anode-side reactant feed, particularly to its fluid delivery unit or control valve. Preferably, the control unit also determines a setpoint or manipulated value for the cathode-side feed rate and transmits this value to the cathode-side reactant feed, particularly to its fluid delivery unit or control valve. Preferably, the combined determination step is a computational process, particularly an optimization process, which, depending on at least one operating parameter of the electrochemical system, determines a value for both the cathode-side feed rate and the anode-side feed rate, particularly in mutual dependence.Preferably, the control unit determines the feed rates as a function of at least one temperature of the electrochemical system, in particular the electrochemical cell unit and / or another fluid-carrying component of the electrochemical system, as an operating parameter. A "fluid-carrying component" is preferably understood to be a component that is intended for direct contact with at least one of the reactants and / or at least one of the products and that is fluidically connected to the electrochemical cell unit. The fluid-carrying component can be arranged downstream or upstream of the electrochemical cell unit with respect to the at least one reactant and / or the at least one product. For example, the fluid pumping units and / or control valves already mentioned are fluid-carrying components in this sense.The electrochemical system can comprise, as fluid-carrying components, for example, at least one heat exchanger, at least one reformer, at least one afterburner, at least one evaporator, at least one reactant preheater with an electric heater, or the like. Preferably, the electrochemical system comprises at least one cell temperature sensor, which measures a cell temperature processed by the control unit as an operating parameter and which is arranged, in particular, at a fluid outlet, especially an air outlet, of the electrochemical cell unit. Preferably, the electrochemical system comprises at least one component temperature sensor, which measures a component temperature processed by the control unit.

[0016] - 4 -

[0017] ratio measures as an operating parameter and which is located, in particular, at a fluid outlet of a fluid-carrying component of the electrochemical system.

[0018] The design according to the invention allows for a significantly high efficiency of the electrochemical system. In particular, the feed rates can be advantageously set and controlled in a consistently balanced manner. Specifically, the ratio of the reactants in the electrochemical cell unit can be reliably and advantageously coordinated. In particular, the risk of an unnecessarily high feed rate of one of the reactants can be advantageously minimized. Specifically, the risk of overheating of the electrochemical system and / or fuel depletion in the electrochemical cell unit can be advantageously minimized.

[0019] It is further proposed that the feed rates be set using model predictive control. Preferably, a model, in particular a temperature model, of the electrochemical system is stored in the control unit. Preferably, the control unit uses the model to predict changes in the operating parameter when the feed rates are varied. Preferably, the control unit determines the actual state of the operating parameter, for example, using the cell temperature sensor and / or the component temperature sensor. Preferably, the control unit determines a target profile of the operating parameter, particularly preferably based on the actual state, and especially through an optimization process. Preferably, the control unit decomposes the target profile into a temporal sequence of sub-steps.Preferably, the control unit adjusts the feed rates to the values ​​used to determine the first step of the target curve of the operating parameter. Particularly preferably, the control unit performs the model predictive control in parallel with the operation of the electrochemical system, i.e., online. Preferably, the control unit operates according to the receding horizon principle to perform a further adjustment of the feed rates and, after setting the feed rates of the first step, determines an updated actual state of the operating parameter and, based on this, an updated target curve of the operating parameter. This is achieved through the embodiment according to R.414130.

[0020] - 5 -

[0021] The risk or extent of exceeding critical system limits of the electrochemical system can be advantageously minimized. In particular, deviations from the target behavior of the electrochemical system can be advantageously counteracted early on, especially in advance. Specifically, the duration of any deviation can be advantageously kept short, particularly despite the relatively large thermal mass and relatively slow response of the electrochemical system.

[0022] Furthermore, it is proposed that a 1D temperature model of the at least one electrochemical cell unit be evaluated in the joint determination step. A "1D model" of a physical quantity of a component preferably means that the physical quantity is resolved with respect to at least one, and more precisely, one spatial dimension. The at least one spatial dimension parallel to a flow direction of the at least one reactant and / or the at least one product through the component is particularly preferred. Preferably, the temperature model specifies a temperature within the electrochemical cell unit as a function of a position along a flow direction through the electrochemical cell unit.The control unit preferably evaluates the temperature model at several locations, in particular at least three different positions, to determine the spatial temperature profile within the electrochemical cell unit. The control unit can use the evaluated positions as reference points for interpolating a temperature profile and / or for determining the temperature profile by sampling. Preferably, the control unit evaluates the temperature model in model predictive control by varying the feed rates. More preferably, the control unit compares the temperature profile, in particular as a whole and / or by sampling, with at least one temperature limit, in particular a global temperature limit and / or with position-specific local temperature limits, of the electrochemical cell unit to define a permissible range of feed rates.Preferably, the temperature model is based on an energy balance of the electrochemical cell unit, in which in particular the chemical energy and in particular thermal energy carried by at least one of the reactants and / or one of the products, an electrical power of the R.414130.

[0023] - 6 -

[0024] The electrochemical cell unit is compared to the electrochemical cell unit. The control unit preferably divides the electrochemical unit into several model sections along the flow direction, for each of which it performs the energy balance calculation. Preferably, the temperature model is based on the assumption that thermal equilibrium exists at the outlet of the electrochemical cell unit, particularly at the outlet of each model section. Preferably, the control unit sets the outlet temperature of one of the model sections equal to the inlet temperature of the model section immediately downstream. In particular, the control unit sets the outlet temperature of the electrochemical cell unit, especially of the last model section in the flow direction, equal to the outlet temperature of the at least one reactant and / or product.Alternatively, in the joint determination step, an OD temperature model of the at least one electrochemical cell unit is evaluated, which does not take into account the spatial resolution of the electrochemical cell unit. The inventive design allows for the advantageously simple modeling of a realistic temperature profile within the electrochemical cell unit. In particular, advantageously reliable adherence to the temperature limit can be achieved. Furthermore, advantageously stable control based on the temperature model can be achieved.

[0025] Furthermore, it is proposed that in the joint determination step, a temperature model of at least one fluid-carrying component of the electrochemical system is evaluated, which is arranged downstream or upstream of the at least one electrochemical cell unit. To distinguish it, this temperature model is hereinafter referred to as the component temperature model. In the simplest case, the component temperature model is position-independent and, in particular, outputs only a single temperature of the component. Alternatively, the component temperature model, like the temperature model of the electrochemical cell unit, is designed as a 1D temperature model. Preferably, the control unit evaluates the component temperature model in model predictive control by varying the feed rates. Preferably, the control unit compares a value with that of R.414130.

[0026] - 7 -

[0027] The component temperature model determines the temperature of the component using at least one temperature limit value to define a permissible range for the feed rates. Preferably, the component temperature model is based on an energy balance of the component, in which, in particular, the chemical energy carried by at least one of the reactants and / or one of the products at the entry and exit of the component is compared. The design according to the invention allows for the implementation of an advantageously comprehensive control concept for the electrochemical system. In particular, the number of different control loops that need to be coordinated can be advantageously kept small.

[0028] It is further proposed that a fixed prediction horizon be used in at least one process step. The prediction horizon is the total duration of the target profile of the operating parameter, which the control unit determines in one iteration of the common determination step. Preferably, the prediction horizon is kept constant, at least during steady-state operation of the electrochemical system. The fixed prediction horizon is preferably selected to correspond to a typical thermal response time of the electrochemical system in order to enable a realistic prediction of the temperature development. For example, the control unit sets a constant prediction horizon of more than 60 seconds, preferably more than 120 seconds, and particularly more than 150 seconds.For example, the control unit sets a constant prediction horizon of less than 360 seconds, preferably less than 240 seconds, and particularly less than 200 seconds. In an advantageously simple embodiment, the prediction horizon is constant in every operating phase in which the model predictive control is active, especially also during changes in the operating point of the electrochemical system. The design according to the invention advantageously keeps the computational effort during the common determination step constant. Furthermore, the control system can be advantageously kept robust against varying operating conditions. R.414130.

[0029] - 8 -

[0030] Furthermore, it is proposed that a variable prediction horizon be used in at least one process step. Preferably, the control unit determines the prediction horizon as a function of at least one system parameter of the electrochemical system, such as an electrical load connected to the electrochemical system or a temperature dynamic of the system, particularly during an operating point change, start-up, or shutdown of the electrochemical system. In particular, the control unit shortens the prediction horizon during operating point changes, start-up, or shutdown of the electrochemical system compared to the prediction horizon during steady-state operation of the electrochemical system. The design according to the invention allows the control system to respond advantageously and flexibly to varying operating conditions of the electrochemical system.In particular, the risk of damage and / or the extent of wear and tear on the electrochemical system during non-stationary operating phases of the electrochemical system can be advantageously kept low.

[0031] Furthermore, it is proposed that in at least one process step of the process, an operating parameter of the electrochemical system is optimized by varying at least one of the feed rates. Preferably, the control unit performs the aforementioned optimization process to determine the target profile of the operating parameter. For example, the control unit maximizes a product output rate and / or minimizes the electrical power absorbed or used by the electrochemical system and / or minimizes the input of reactants, in particular fuel, to achieve a predetermined electrical power and / or product output rate. For example, the control unit maximizes the electrical efficiency of the electrochemical cell unit and / or the electrochemical system, in particular a ratio of absorbed or used electrical power to the output of the electrochemical system.The electrical energy output of the electrochemical cell unit and / or the entire electrochemical system is converted into chemical energy of at least one of the reactants and / or at least one of the products. The control unit can, for example, use an indirect method in the optimization process (R.414130).

[0032] - 9 -

[0033] Based on Pontryagin's Minimum Principle, such as indirect shooting or forward backward sweep methods, and / or a direct method, such as direct shooting, direct multiple shooting, direct collocation, and / or dynamic programming, the desired profile of the operating parameter is used, below which the operating quantity becomes extreme. The inventive design allows the feed rates to be advantageously and efficiently adjusted to the entire electrochemical system.

[0034] It is further proposed that in at least one process step, an operating parameter of the electrochemical system is optimized by varying at least one electrochemical conversion rate of at least one of the reactants in the electrochemical cell unit. Preferably, the target profile of the operating parameter is determined by varying the electrochemical conversion rate of one of the reactants. Preferably, the optimization process outputs an optimal setpoint for the electrochemical conversion rate at which the operating parameter is extremal. Preferably, the control unit derives a setpoint for the feed rate of the reactant from the optimal setpoint for the conversion rate. In particular, the control unit determines the conversion rate of the reactant using the optimal setpoint for the conversion rate, an actual value of the conversion rate, and an electric current flow, particularly a setpoint, in the electrochemical cell unit.The control unit determines the actual value of the conversion rate, for example, using a method described in DE 102021 212685 A1. The design according to the invention allows a limit value for the conversion rate to be advantageously and reliably maintained.

[0035] Furthermore, it is proposed that the cathode-side feed rate be determined as a function of an anode-side conversion rate and / or the anode-side feed rate as a function of a cathode-side conversion rate. Preferably, in the joint determination step, particularly the optimization process, the control unit uses as a constraint adherence to a maximum value of the cathode-side conversion rate and adherence to a maximum value of the anode-side conversion rate. Preferably, in the joint determination step, the control unit determines the cathode-side conversion rate as a function of the maximum value of the R.414130

[0036] - 10 -

[0037] The control unit preferably determines the anode-side conversion rate as a function of the maximum value of the cathode-side conversion rate and the maximum value of the anode-side conversion rate in a joint determination step. The design according to the invention allows advantageously compatible feed rates to be determined in a consistently advantageous manner.

[0038] Furthermore, an electrochemical system is proposed comprising at least one electrochemical cell unit, at least one cathode-side reactant supply connected to the electrochemical cell unit, at least one anode-side reactant supply connected to the electrochemical cell unit, and at least one control unit for carrying out a method according to the invention. The electrochemical cell unit preferably comprises at least one solid oxide fuel cell or a solid oxide electrolysis cell, alternatively at least one polymer electrolyte fuel cell or a polymer electrolyte electrolysis cell, alternatively at least one alkali fuel cell or an alkali electrolysis cell, or the like, as the electrochemical cell. The design according to the invention allows for the provision of an advantageously efficient and low-wear electrochemical system.

[0039] The method and / or the electrochemical system according to the invention are not to be limited to the application and embodiment described above. In particular, the method and / or the electrochemical system according to the invention may, to achieve a functionality described herein, comprise a different number of individual elements, components, cell units, and process steps than that specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also to be considered disclosed and freely usable.

[0040] Drawings R.414130

[0041] - 11 -

[0042] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0043] They show:

[0044] Fig. 1 shows a schematic fluid circuit diagram of an electrochemical system according to the invention designed as a fuel cell system and

[0045] Fig. 2 is a schematic drawing to illustrate a model of the electrochemical system according to the invention in the course of a method according to the invention.

[0046] Description of the exemplary embodiment

[0047] Figure 1 shows an electrochemical system 10, which is designed as an exemplary fuel cell system. The electrochemical system 10 comprises an electrochemical cell unit 12, which is preferably configured as a fuel cell unit. The electrochemical cell unit 12 preferably comprises a plurality of fuel cells, in particular solid oxide fuel cells, which can be arranged in one or more stacks. The electrochemical cell unit 12 is preferably designed to electrochemically react a fuel and an oxygen-containing fluid, in particular ambient air, as reactants. The electrochemical cell unit 12 is shown here functionally as a single fuel cell. The electrochemical cell unit 12 preferably comprises a fuel electrode for direct contact with the fuel, which is in particular connected as an anode 28.The electrochemical cell unit 12 preferably comprises an oxygen electrode for direct contact with the oxygen-containing fluid, which is particularly connected as the cathode 26 R.414130.

[0048] - 12 -

[0049] A gas-tight electrolyte, preferably oxygen-conducting, is arranged between the oxygen electrode and the fuel electrode. The electrochemical system 10 is designed, for example, to use hydrogen, ammonia, methane, another hydrocarbon, and / or a mixture of several of the aforementioned substances, particularly in the form of natural gas or biogas, as fuel.

[0050] The electrochemical system 10 comprises at least one cathode-side reactant supply 14 connected to the cathode 26, here exemplified as an air supply. The cathode-side reactant supply 14 preferably comprises a fluid conveying unit 30, which is in particular designed as a blower or compressor, for transporting the oxygen-containing fluid to the cathode 26. The cathode-side reactant supply 14 includes, for example, a preheater 36 designed as a heat exchanger for preheating the oxygen-containing fluid. A primary side of the preheater 36 is preferably connected to an exhaust line 42 of the electrochemical system 10.

[0051] The electrochemical system 10 comprises at least one anode-side reactant supply 16 connected to the anode 28, which is here exemplified as a fuel supply. The anode-side reactant supply 16 preferably comprises a fluid conveying unit 32, which is in particular configured as a blower or compressor, for transporting the fuel to the anode 28. The anode-side reactant supply 16 includes, for example, a preheater 38 for preheating the fuel. Depending on the fuel used, the anode-side reactant supply 16 may also include, for example, a reformer 40 for reforming the fuel before it enters the electrochemical cell unit 12.

[0052] The electrochemical system 10 preferably comprises an afterburner 54 for the thermal conversion of fuel residues leaving the electrochemical cell unit 12. The afterburner 54 is preferably connected to an anode outlet 58 of the anode 28 and to a cathode outlet 56 of the cathode 26. The exhaust line 42 is preferably connected to a fluid outlet of the afterburner 54. The electrochemical system 10 includes, for example, a recirculation line 44 with a recirculation pumping unit R.414130.

[0053] - 13 -

[0054] 34, to a refeed of an anode-side exhaust gas of the electrochemical cell unit 12 from the anode outlet 58 into the anode-side reactant supply 16, in particular upstream of the reformer 40 and in particular downstream of the preheater 38.

[0055] The electrochemical system 10 comprises at least one control unit 24 for carrying out a process for operating an electrochemical system 10. In at least one process step of the process, the control unit 24 sets a cathode-side feed rate of the cathode-side reactant feed 14, in particular by controlling the fluid delivery unit 30 of the cathode-side reactant feed 14. In at least one process step of the process, the control unit 24 sets an anode-side feed rate of the anode-side reactant feed 16, in particular by adjusting the fluid delivery unit 32 of the anode-side reactant feed 14. In an extension of the process, the control unit 24 can additionally set a recirculation rate of the recirculated exhaust gas, in particular by controlling the recirculation delivery unit 34. The cathode-side feed rate and the anode-side feed rate, and optionally the recirculation rate, are controlled by the control unit 24.The recirculation feed rate is determined by the control or regulating unit 24 in at least one joint determination step of the procedure.

[0056] The feed rates are set by the control unit 24 using model predictive control. The model predictive control preferably determines a resulting temperature of the electrochemical cell unit 12 and / or other fluid-carrying components 22, in particular the afterburner 54, in advance of changes in the feed rates, in order to determine a suitable setpoint for the feed rates. In the model predictive control, the control unit 24 evaluates a 1D temperature model 18 of the at least one electrochemical cell unit 12. The control unit 24 also evaluates a temperature model 20 of the afterburner 54. The temperature models 18 and 20 preferably depend on the feed rates as variables. The temperature models 18 and 20 are explained in more detail in Figure 2.In predictive control, the control unit 24 preferably calculates a target temperature profile for the duration of a prediction horizon, starting from an actual temperature value. R.414130.

[0057] - 14 -

[0058] Preferably, the control unit 24 uses a fixed prediction horizon, for example 180 seconds, for evaluating the temperature models 18, 20, at least during a steady-state operating phase of the electrochemical system. During an operating point change, the control unit 24 can use the fixed prediction horizon or a variable prediction horizon for evaluating the temperature models 18, 20.

[0059] To determine the target temperature profile, the control unit 24 optimizes an operating parameter of the electrochemical system 10 in an optimization process by varying at least one of the feed rates, in particular the cathode-side feed rate and, if applicable, the recirculation rate, and by varying at least one electrochemical conversion rate of at least one of the reactants, in particular the system-wide fuel utilization of the fuel. For example, in the optimization step, the control unit 24 maximizes an electrical efficiency of the electrochemical system, in particular a ratio of net electrical power to the chemical energy of the fuel.The net electrical power is preferably the electrical power provided by the electrochemical cell unit 12 less any electrical power consumed by the electrochemical system 10 itself, for example, by the fluid delivery units 30, 32, 34, by sensors, by the control unit 24, etc. Preferably, the control unit 24 optimizes the operating parameters under constraints. Preferably, the control unit 24 uses as a constraint that the cathode-side feed rate, the system-wide fuel utilization, a cathode-side conversion rate, the temperature of the electrochemical cell unit 12, and / or the temperature of the afterburner remain below a respective limit value. Preferably, the control unit 24 adjusts the cathode-side fluid delivery unit 30 to the cathode-side feed rate values ​​for which maximum efficiency has been found.Preferably, the control or regulating unit 24 sets the anode-side fluid delivery unit 32 to the values ​​of the anode-side supply rate, which it derives from the fuel utilization value for which the maximum efficiency has been found. R.414130.

[0060] - 15 -

[0061] Figure 2 shows the temperature models 18 and 20. The temperature model 18 of the electrochemical cell unit 12 is one-dimensional. Preferably, the electrochemical cell unit 12 is subdivided along a fuel flow direction into, in particular, equally sized model sections 46, 48, 50, and 52 (here, by way of example, four sections) in order to resolve a spatial temperature profile through the electrochemical cell unit 12 in one spatial dimension. Preferably, an actual value of an output temperature of the electrochemical cell unit 12 at its cathode outlet 56 and / or anode outlet 58 is detected by a temperature sensor of the electrochemical system 10.The control unit 24 preferably determines a change in the temperature of the model sections 46, 48, 50, 52 based on the proportion of the chemical energy of the fuel converted in the respective model section 46, 48, 50, 52, less any electrical energy 60 extracted, and in particular based on the input and output, especially thermal, energy of the reactants and / or products. The converted chemical energy is the total chemical energy multiplied by the conversion rate, i.e., the fuel utilization, and optionally a model section-specific factor. Preferably, in the optimization step, the control unit 24 uses as a constraint that the temperature of each model section 46, 48, 50, 52 must remain below a certain limit, in particular the same limit or a model section-specific limit.

[0062] As an example, a zero-dimensional model without spatial resolution is used here as the temperature model 20 of the afterburner. Preferably, an actual temperature value of the afterburner 54 at its fluid outlet and / or in the exhaust pipe 42 is recorded by a temperature sensor of the electrochemical system 10. The control unit 24 preferably determines a change in the temperature of the afterburner 54 based on the remaining chemical energy of the fuel after exiting the electrochemical cell unit 12, i.e., the total chemical energy less the chemical fraction already converted in the electrochemical cell unit 12. The control unit 24 preferably determines the fraction converted in the electrochemical cell unit 12 based on the conversion rate, i.e., the fuel utilization, multiplied by the chemical energy of the fuel.

Claims

R.414130 - 16 - Claims 1. A method for operating an electrochemical system (10) comprising at least one electrochemical cell unit (12), a cathode-side reactant supply (14) to the electrochemical cell unit (12) and at least one anode-side reactant supply (16) to the electrochemical cell unit (12), wherein in at least one process step a cathode-side feed rate of the cathode-side reactant supply (14) is set and wherein in at least one process step an anode-side feed rate of the anode-side reactant supply (16) is set, characterized in that the cathode-side feed rate and the anode-side feed rate are determined in at least one common determination step.

2. Method according to claim 1, characterized in that the feed rates are set by means of a model predictive control.

3. Method according to claim 1 or 2, characterized in that in the common determination step a 1D temperature model (18) of the at least one electrochemical cell unit (12) is evaluated.

4. Method according to one of the preceding claims, characterized in that in the common determination step a temperature model (20) of at least one fluid-carrying component (22) of the electrochemical system (10) is evaluated, which is arranged downstream or upstream of the at least one electrochemical cell unit (12).

5. A method according to any of the preceding claims, characterized in that a fixed prediction horizon is used in at least one method step. R.414130 - 17 - 6. Method according to one of the preceding claims, characterized in that a variable prediction horizon is used in at least one method step.

7. Method according to one of the preceding claims, characterized in that in at least one process step an operating parameter of the electrochemical system (10) is optimized by varying at least one of the feed rates.

8. Method according to one of the preceding claims, characterized in that in at least one process step an operating parameter of the electrochemical system (10) is optimized by varying at least one electrochemical conversion rate of at least one of the reactants in the electrochemical cell unit (12).

9. Method according to one of the preceding claims, characterized in that the cathode-side feed rate is determined as a function of an anode-side conversion rate and / or the anode-side feed rate is determined as a function of a cathode-side conversion rate.

10. Electrochemical system (10) comprising at least one electrochemical cell unit (12), comprising at least one cathode-side reactant supply (14) connected to the electrochemical cell unit (12), comprising at least one anode-side reactant supply (16) connected to the electrochemical cell unit (12) and comprising at least one control or regulating unit (24) for carrying out a method according to one of the preceding claims.

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