EP4197046A1

EP4197046A1 - Temperature-control device for a stack-like energy store or converter, and a fuel cell stack having a temperature-control device of said type

Info

Publication number: EP4197046A1
Application number: EP21765574.5A
Authority: EP
Inventors: Felix HENNERSPERGER; Volker Harbusch; Matthias WÖSSNER
Original assignee: Siqens GmbH
Current assignee: Siqens GmbH
Priority date: 2020-08-14
Filing date: 2021-08-06
Publication date: 2023-06-21
Also published as: WO2022033994A1; US20230299312A1; CN116391281A

Abstract

The present invention relates to a temperature-control device for controlling the temperature of a stack-like energy store or converter formed from multiple cells, comprising multiple plate-like heat-conducting elements arranged between the cells, wherein the temperature of the cells is controlled by heat conduction via the plate-like heat-conducting elements, multiple temperature-control ribs which are arranged outside the cells and which serve for changing the flow direction of the temperature-control air flow, wherein the temperature-control ribs are thermally coupled to the heat-conducting elements, and wherein the temperature of the plate-like temperature-control ribs is controlled by means of convection by impingement of a temperature-control air flow and/or by heat conduction via further means, the means for influencing the temperature-control air flow and/or for temperature-control air guidance, which means are configured to change a flow direction and/or a flow speed of the temperature-control air flow, wherein the means are structurally configured and/or arranged such that several of the temperature-control ribs can be impinged on by a temperature-control air volume flow such that a majority of the cells are approximately uniformly heatable or coolable in a cell centre, and wherein the means for influencing the temperature-control air flow and/or for temperature-control air guidance comprise one and preferably two or more of the following components: at least one further temperature-control rib, the shape and/or arrangement of which differs from the shape and/or the arrangement of the other temperature-control ribs, and/or at least one resistance element for changing the temperature-control air flow by locally distributing pressure losses and/or by generating turbulence, and/or at least one temperature-control air guide element for further changing the flow direction and/or the flow speed of the temperature-control air flow in relation to the change of the flow direction and/or the flow speed of the temperature-control air flow by the temperature-control ribs, and/or at least one temperature-control element, which is configured as a heat exchanger.

Description

Tempering device for a stack-type energy store or converter and a fuel cell stack with such a tempering device

The present invention relates to a temperature control device for a fuel cell stack and a fuel cell stack with such a temperature control device.

A fuel cell is a device for generating electrical energy through the reaction of fuel (e.g. hydrogen, propane, natural gas, methanol) and oxygen. In its simplest form, such a cell essentially consists of supply plates with channels for the fuel/hydrogen supply (anode) and supply plates for the supply of air/oxygen (cathode), these plates being separated and sealed from one another by an ion-conducting membrane or layer. For example, hydrogen can either be fed directly to the cell as a fuel or can be produced by conversion from another fuel, for example methane, methanol, propane or another suitable hydrocarbon, ether or alcohol. In practice, in order to increase the output, several units consisting of anode and cathode, so-called cells, are connected in series to form a fuel cell stack. The different types of fuel cells are classified on the one hand by the electrolyte (e.g. polymer electrolyte membrane fuel cell, PEMFC) and on the other hand by the fuel used (e.g. direct methanol fuel cell, DMFC).

In order for a fuel cell stack to reach its operating temperature, it must be heated by means of a heating device (for example electric heating, heating medium or burner) when a corresponding fuel cell system is started.

A gas-operated starting system for a reformer fuel cell system is disclosed in EP 1 703 578 A1. This comprises at least one reformer, a fuel cell and a burner arranged outside the fuel cell, such as a surface burner with a low flame height, e.g. a burner with a ceramic or metallic surface or a surface made of fiber materials, such as a ceramic fiber mat coated with silicon carbide Heat reformer and fuel cell stack.

DE 199 10 387 A1 discloses a fuel cell battery with a stack and a heating device. The heat provided by the heating device should be able to be used to heat up the fuel cell stack. The heating device preferably comprises a heating element such as a catalytic burner and/or an electrical heating element and/or a reformer device.

During operation, on the other hand, a fuel cell stack must be cooled. Otherwise, due to the exothermic reaction taking place inside, it would heat up to such an extent that the fuel cell stack would quickly degrade.

DE 199 31 061 A discloses a fuel cell system with a cooling circuit. In this case, a heat sink is connected to a supply line for the fuel and/or the oxidizing agent in such a way that a corresponding heat exchange can take place. It should thus be possible to heat the gas/fluid streams of the fuel cell with the waste heat from a cooling system.

An embodiment of an HTPEM fuel cell with liquid cooling is described in DE 10 2007 044 634 B4.

EP 1 498 967 A2 describes a PEMFC in which cooling air is guided through cooling plates integrated into a fuel cell stack with cooling channels open to the outside. US 2011 013 60 30 A1 describes cooling fins for an HT-PEMFC, which are designed as an extension of a supply plate. WO 2011 154 084 A2 discloses a fuel cell stack with cooling fins, with additional cooling channels being provided as a substructure in these fins. US 809 73 85 B2 discloses a combination of thermally conductive material and cooling fins to cool a fuel cell stack. US Pat. No. 049,388,33 A discloses an arrangement in which a fuel cell stack is formed from cooling and supply plates made of metal. A layer of heat-conducting Grafoil is inserted between these plates. US 680 88 34 B2 discloses a fuel cell stack for a polymer electrolyte fuel cell. To improve the cooling, this has cooling ribs on one longitudinal side, which consist of a foil made of expanded graphite and protruding beyond the fuel cell stack towards the longitudinal side. US Pat. No. 592,8807 A describes a supply plate for a PEM fuel cell with an integrated seal. The plate itself is made of a plastically deformable material, such as graphite foil, into which the channels are pressed. The sealing effect is created by a bump on this material which is compressed during assembly.

In the case of fuel cell stacks, there is often the challenge of achieving an even temperature distribution across the fuel cell stack, since the heat generated during operation must be dissipated evenly. At present, this is often implemented using an additional oil or water cooling system integrated into the fuel cell stack, which, however, is error-prone, complex and expensive. Furthermore, this requires cooling plates in the fuel cell stack, which represent an additional weight and cost factor and often also have to be specially sealed. In addition, these variants are economically difficult to reconcile with internal reforming in the fuel cell stack in separate chambers, since separate reformer rooms with a separate supply would be required for the cooling plates. Flowing through the fuel cell stack with cooling air, as is sometimes the case, has disadvantages such as the large installation space required due to cooling channels integrated in the fuel cell stack, increased weight, poor compatibility with internal reforming in the stack in terms of costs and space, depending on the design or complexity, high temperature difference within the individual cells (influence on performance or degradation), as well as an increased required blower power due to increased pressure loss due to the flow through the internal channels.

The object of the present invention is to provide an efficient device for temperature control, i.e. for heating and cooling, of a fuel cell stack, which is of simple and inexpensive construction and is safe and reliable in operation.

Another object is to provide a device for controlling the temperature of a fuel cell stack, which allows the most homogeneous possible temperature distribution over the individual cells of a fuel cell stack.

This object is achieved with a device according to claim 1. Advantageous configurations thereof are specified in the dependent claims.

The present invention relates to a temperature control device for controlling the temperature of a stack-like energy store or converter formed from a plurality of cells, comprising a plurality of plate-shaped heat conduction elements arranged between the cells, the cells being temperature-controlled via the plate-shaped heat conduction elements by means of heat conduction, a number of temperature-control ribs arranged outside the cells for changing the direction of flow of the temperature control air flow, wherein the temperature control ribs are thermally coupled to the heat conduction elements, and wherein the temperature control of the plate-shaped temperature control ribs takes place by being subjected to a temperature control air flow by means of convection and/or via other means by means of heat conduction, the means for influencing the temperature control air flow and/or for guiding the temperature control air, the are designed for changing a flow direction and / or a flow rate of the temperature control air flow, the means structurally such au are designed and/or arranged such that several of the temperature control ribs can be subjected to a volume flow of temperature control air in such a way that a majority of the cells in a cell center can be heated or cooled approximately uniformly, and the means for influencing the flow of temperature control air and/or for guiding the temperature control air one and preferably two or more of the following components include at least one additional temperature control rib, the shape and/or arrangement of which differs from the shape and/or the arrangement of the other temperature control ribs, and/or at least one resistance element to reduce the temperature control air flow through local distribution of pressure losses and / or to change by vortex formation, and / or at least one tempering air guide element for further changing the flow direction and / or the flow rate of the tempering air flow compared to changing the flow direction and / or the flow rate of the tempering air flow through the tempering ribs and/or at least one temperature control body, which is designed as a heat exchanger.

A fuel cell, in particular a fuel cell stack, an electrolyzer or a redox flow battery is understood as a stack-like energy store or converter within the scope of the present invention. In the context of the present invention, the term “temperature control” is understood to mean heating or cooling of the stack-like energy store or energy converter in order to operate it more efficiently and/or to reach a predetermined operating state more quickly.

The cells are tempered via the plate-shaped heat conduction elements arranged between the cells inside the stack-like energy store by means of heat conduction. This ensures even and efficient tempering. In most cases, devices of this type are only provided on the outer walls of devices to be temperature-controlled. Such an arrangement does not enable uniform temperature control, since a corresponding device can only be temperature controlled from the outside inwards. In addition, foils are known as heat conduction elements, which are arranged between individual cells. However, due to their small thickness, these also do not allow efficient temperature control. Using expensive high-performance material that is difficult to process, such as pyrolytic graphite, is not economical for many applications.

The invention is characterized in that the plurality of plate-shaped heat conduction elements arranged between the cells are provided.

The heat conduction elements can have a thickness of more than 0.9 mm or 1 mm or 1.2 mm and preferably more than 1.4 mm. For example, the thickness can be 2.0 mm or 3.0 mm. The greater the thickness, the better the temperature distribution. However, a greater thickness results in a greater length of the cell stack, which is disadvantageous in terms of installation space. A maximum thickness of 3.5 mm or 3.75 mm or 4.0 mm seems reasonable for most applications.

Due to their thickness, the heat conduction elements have a higher and more efficient thermal conductivity compared to foils.

In addition, the present invention is characterized in that the several temperature control ribs arranged outside the cells are provided, with the temperature control of the plate-shaped temperature control ribs being carried out by applying a temperature control air flow in a temperature control direction by means of convection and/or other means by means of heat conduction, and wherein the temperature control -ribs are thermally coupled to the heat conduction elements.

Within the scope of the present invention, a first cell of a stack-like energy store, for example a fuel cell stack, can be referred to as the start row and a last cell as the end row.

The temperature control direction is preferably a main flow direction of the temperature control air flow or a temperature control air volume flow. The temperature control direction can be directed from an initial row to an end row, approximately parallel to one or more side walls of the fuel cell stack and in a main flow direction of the temperature control air provided by a blower device.

The temperature control air flow or the temperature control direction is influenced, among other things, by structural conditions, for example lack of space in one dimension orthogonal to a surface of a component to be cooled, e.g. a fuel cell stack. The fuel cell stack, including the temperature control device, can thus be suitably integrated into a fuel cell system, for example with a low height in one dimension, while at the same time utilizing the advantages of the type of cooling. Accordingly, the temperature control device is extremely compact due to the combination and structural design of the means for influencing the temperature control air flow.

If the tempering ribs are not only thermally coupled to the heat conduction elements, but are also mechanically connected to them, they are referred to below as tempering elements.

If, for example, a temperature control air flow were applied to a fuel cell stack that has similarly designed plates for heat transfer that protrude from the stack, this would lead to a very uneven distribution of the air mass flow or air volume flow and thus to uneven temperature control of the fuel cell stack. According to the conservation of momentum or inertia of the gas particles, among other things, a large part of the air volume flow would flow on the rear plates protruding from the fuel cell stack, while a small air volume flow would flow on the front protruding plates. As a result, the temperature distribution of the fuel cell stack would be non-uniform and would not be sufficient to achieve the longest possible service life of the fuel cell stack at a predetermined setpoint temperature.

If, on the other hand, a temperature control air duct according to the invention is provided, for example by means of the temperature control channel, then the air mass flow or air volume flow is distributed approximately uniformly and a uniform temperature distribution in the fuel cell stack is achieved. The service life is then significantly longer (up to 40 percent) as is the performance of the fuel cell stack (up to 5 percent). In addition, the fan power of a blower device to achieve the same average stack temperature would be lower (by up to 15 percent).

Since fuel cell systems are usually more expensive to purchase than diesel generators, for example, a long service life is important from a market perspective in order to achieve low total cost of ownership.

The service life of the cells is influenced, among other things, by the operating temperature. In the case of high-temperature polymer electrolyte fuel cells (HT-PEM fuel cells), for example, more phosphoric acid evaporates at higher temperatures. For example, cells operated 10 degrees Celsius warmer would degrade significantly faster than cells operated 10 degrees Celsius colder. Since fuel cells continue to degrade disproportionately quickly after degradation has already taken place, among other things due to low potential, one or more worst-performing cells limit the service life of the entire fuel cell stack.

The performance of the fuel cell stack is also influenced by the temperature distribution. Colder cells of the HT-PEM fuel cell stack, for example, would have a disproportionately poorer performance due to lower phosphoric acid proton conductivity at lower temperatures (eg by 10 degrees Celsius). Their sensitivity to components/impurities in the anode gas that are negative for performance, such as carbon monoxide, is increased. A good temperature distribution during operation therefore significantly improves the service life of the fuel cell stack as well as its performance.

For example, the temperature distribution in HT-PEM fuel cells is crucial for the heating-up process, since the fuel cell stack may only be operated when a certain minimum temperature (e.g. 105 degrees Celsius) has been reached, so that water can evaporate so that no phosphoric acid droplets are expelled from the fuel cell or So that product water formed by the fuel cell reaction immediately goes into the gas phase and the phosphoric acid is not diluted by water and its volume increases, which can lead to its discharge and result in degradation of the fuel cell. Since the heating process must be as short as possible in order to meet market requirements, it is advantageous for the fuel cell stack to have a temperature distribution that is as uniform as possible during the heating process. The energy required for the heating process is also lower if it is distributed evenly, which would mean, for example, lower consumption of fuel when obtaining thermal heat from a combustion process or lower consumption of electrical energy from an accumulator.

The invention can be applied to fuel cell stacks (fuel cell stacks) as well as to galvanic elements, primary cells, batteries, secondary cells, accumulators, redox flow batteries, electrolyzers and similar assemblies/components such as microreactors, reactors, heat exchangers, mixers and burners with stacked reaction spaces (cells) and similar structures with layered or stacked functional spaces/components (cells) can be used. The cells thus represent, among other things, cells in the sense of fuel cell, electrolyzer, accumulator or battery technology or functional units or spaces that fulfill one or more function(s). The individual cells can be closed or open systems act. In the context of the present invention, such devices are referred to as stack-type energy stores or energy converters.

The cells can contain electrolyte membranes, polymer electrolytes, electrolyte foils, electrolyte layers or electrolyte plates and/or, for example, solid electrolytes or liquid electrolytes. Furthermore, the cells can contain catalysts or catalytically active substances. The cells can be formed or constructed from electrically conductive and/or non-electrically conductive components.

In the following, advantageous configurations of the present invention are explained on the basis of a fuel cell stack. In the case of a fuel cell stack, for example, the membrane electrode units or the combination of membrane electrode units with associated sealing elements and associated electrically conductive plates (for example bipolar plates) and/or any other associated components can form the cells.

The multiple temperature control ribs assigned to a side wall of the device can at least partially have surfaces of different sizes and/or at least partially have the same surface area and/or that the temperature control ribs have recesses of different sizes and/or the same size, the recesses being provided for passing through and influencing the temperature control air flow , and where the The size of the recesses increases or decreases in the temperature control direction and/or that the temperature control ribs and/or their recesses at least partially delimit and/or form one or more temperature control air ducts.

The resistance elements can be arranged in the area of two adjacent temperature control ribs and approximately orthogonally to the temperature control ribs, the resistance elements being approximately plate-shaped and preferably having one or more openings or recesses.

Within the scope of the present invention, the resistance elements are also referred to as spacers or elements if they are arranged, for example, orthogonally between two adjacent tempering ribs and keep them at a predetermined distance.

The temperature control ribs and/or the temperature control air guide elements can form a temperature control air channel that preferably tapers in the temperature control direction and/or one or more temperature control air ramps.

The temperature control body or bodies can be designed as a heat exchanger device, wherein the heat exchanger device can have ribs and/or the ribs of the heat exchanger device can be at least partially the temperature control ribs.

One or more of the means for influencing the temperature control air flow can form one (or more) temperature control channel that tapers in the temperature control direction. Additionally and/or alternatively it is also conceivable that one or more temperature control channels widening in the temperature control direction are provided.

By providing a temperature control channel, the temperature control air can be better used for cooling or heating, since the air distribution, the temperature distribution and the heat transfer are significantly improved.

The plate-shaped temperature control ribs are uniformly flown against by a narrowing or tapering temperature control channel and at the same time the thickness of the air boundary layer is locally reduced.

Furthermore, a flow generation device can be provided for forming the temperature control air flow and for acting on the means for influencing the temperature control air flow in the temperature control direction.

In addition, at least one temperature control air supply can be provided for applying a temperature control air flow to one or more of the means in a temperature control direction from a starting row of the cell stack to an end row, and/or at least one temperature control air outlet can be provided for removing the temperature control air from the temperature control device, with the Temperature control air supply and the temperature control air discharge are part of the temperature control air duct by means of the temperature control channel.

The temperature control ribs or the temperature control elements can be structurally designed in such a way that the flow resistance of the temperature control air duct increases in the temperature control direction via the temperature control channel, and/or that all cells can be subjected to approximately the same volume flow (or mass flow) of temperature control air, and/or that the temperature control ribs and/or the temperature control elements delimit in sections at least one temperature control channel, which essentially extends in the temperature control direction and whose cross section decreases in the temperature control direction, and/or that a cross section of the temperature control channel tapers in the temperature control direction, and/or that between the temperature control ribs and/or or the tempering elements and approximately orthogonally to these the resistance -or. Spacer elements are arranged so that the heat transfer surfaces of the temperature control ribs and/or the temperature control bodies and/or the temperature control air guide means become larger in the temperature control direction, and/or that the resistance elements are arranged between the temperature control ribs and/or the temperature control elements, so that the flow against the temperature control ribs and/or the Temperature control elements with temperature control air there is a higher heat transfer from or to the temperature control ribs and/or the temperature control elements, and/or that the temperature control bodies are arranged on the temperature control ribs and/or the temperature control elements, so that a higher heat transfer surface means better heat transfer from and to the temperature control ribs.

The spacer elements can preferably be provided to increase the heat transfer.

Cross sections and/or the number of one or more temperature control air inlets and/or one or more temperature control air discharges can be matched to one another in such a way that the temperature of a cell stack is approximately evenly controlled and/or that the flow of the temperature control ribs with the temperature control air flow is automatically controlled by a control device Hand of operating parameters of the cell stack is regulated and / or controlled.

Sections of the temperature control channel can be delimited transversely to the temperature control direction by the temperature control air guiding elements and/or by the temperature control ribs, a side wall of a cell stack and a housing surrounding the cell stack.

The plate-shaped heat conduction elements can form sealing elements of the cell stack.

The temperature control ribs can be designed to be electrically insulating from other temperature control ribs and/or from heat conducting elements and/or from temperature control ribs and/or from resistance elements and/or from temperature control bodies.

The electrical insulation can be made electrically insulating by a suitable material such as micanite or by an electrically non-conductive coating such as silicone resin or electrically non-conductive means.

In particular, a fuel cell stack can be provided according to the invention. This includes several fuel cells connected in series, which form the approximately cuboid fuel cell stack, where at least one side wall or preferably two, in particular opposing, or three or four side walls are provided with a temperature control device according to the invention.

The temperature control device can have one or more temperature control air inlets and one or more temperature control air outlets per side wall of the fuel cell stack.

A temperature sensor for measuring the temperature of the fuel cell stack can be coupled to at least one temperature control element.

It is thus possible to achieve an even or homogeneous temperature distribution over all cells of a fuel cell stack, since the heat generated during operation can be dissipated evenly. At present, this is often implemented using an additional oil or water cooling system integrated into the cell stack, which, however, is error-prone, complex and expensive. Furthermore, this requires cooling plates in the stack, which represent an additional weight and cost factor and often also have to be specially sealed. The temperature control device according to the invention, on the other hand, is extremely cost-effective, has a simple structure and does not change the internal structures of a fuel cell stack, if at all.

Furthermore, the installation space in a fuel cell system can be used in a suitable manner by the temperature control device according to the invention if, for example, there is not enough installation space on a side surface above or below the fuel cell stack for an air supply, distribution, heating device and/or blower device. A structure of a fuel cell system is therefore simpler and more space-saving.

The heating device can be attached to a side wall of the housing of the fuel cell stack, for example. Alternatively, such a fan can be arranged at a distance from the fuel cell stack and coupled to the temperature control device via a corresponding channel.

A defined temperature control air flow, e.g. by means of the temperature control duct, enables an even temperature distribution (due to the air flow). Without such a temperature control air duct, there would be a large temperature difference within the fuel cell stack, since the main temperature control air flow would flow in the temperature control direction and several temperature control ribs would flow little or not at all. Here, among other things, the momentum of the gas particles plays a role.

Sections of the temperature control channel can be delimited transversely to the temperature control direction by the temperature control ribs and/or the resistance elements and/or the temperature control air guide elements and/or by one or more temperature control bodies and/or a side wall of a fuel cell stack and/or a housing surrounding the fuel cell stack, and the plate-shaped Temperature control ribs can be integrally formed on plate-shaped heat conduction elements and form temperature control elements, and the heat conduction elements can be arranged between individual cells of a fuel cell stack, so that the plate-shaped temperature control ribs are mechanically coupled to the fuel cell stack in such a way that the temperature of the fuel cell stack is controlled via the plate-shaped heat conduction elements by means of heat conduction, and the plate-shaped tempering ribs are tempered by means of convection. The temperature control air guide elements can be formed from individual plate-shaped elements which extend approximately or essentially in the temperature control direction or parallel to the temperature control direction or are inclined at an acute angle relative to the temperature control direction. These are referred to below as longitudinal air guiding elements.

The temperature control air guiding elements can be formed from individual temperature control air guiding elements which extend approximately or substantially transversely to the temperature control direction or are inclined at an obtuse angle relative to the temperature control direction. These are referred to below as transverse air guide elements.

The tempering air guiding elements can consist, for example, of a material such as micanite/mica, aluminum, thermally conductive ceramics, high-performance polymer or expanded graphite or, for example, of ceramic fiber boards, glass fiber boards or heat pipes. In order to meet the requirements for the tempering air guide elements of an HT-PEM fuel cell, high strength, inexpensive manufacturability, high temperature resistance (e.g. up to 250°C) and also non-electrically conductive properties, the choice of material is limited, with the material micanite/mica being suitable proved.

The temperature control channel can be formed in one piece or from a large number of individual elements which are connected or coupled to one another.

In addition to the temperature control channel, which is mainly responsible for the temperature control air distribution or temperature control air duct and thus for the temperature control, the temperature control ribs also delimit a large number of temperature control distribution channels branching off from the temperature control duct, which also play a decisive role in the temperature control of a fuel cell stack and are part of the temperature control air duct .

The temperature control device can have one or more temperature control channels with corresponding temperature control distributor channels per side wall of the fuel cell stack.

Furthermore, a blower device can be provided for applying air to the temperature control air duct or the channels for temperature control.

The plate-shaped heat conduction elements of the temperature control elements can form sealing elements for functional units of a fuel cell stack.

In particular, manifold holes that form the gas distribution channels orthogonally to the supply plates can be sealed by the heat conduction elements. For this purpose, webs can be formed in the supply plates, which ensure locally increased compression of the heat conduction elements in order to achieve a high sealing effect.

Furthermore, the material from which the temperature control elements are made can be made temperature-resistant up to at least 250° C. and, if necessary, resistant to phosphoric acid. In order to provide the necessary sealing properties, the temperature control element or at least its heat conduction element is preferably made of expanded graphite. Likewise, the tempering rib can be made of expanded graphite.

The additional use of the heat conduction elements as a flat gasket instead of, for example, a large number of sealing rings for sealing, can significantly reduce the number of sealing elements and thus the probability of assembly errors. Graphite is well suited as a sealing material for reformer chambers contained in the stack, as other sealing materials can be problematic (e.g. FKM as a high-temperature elastomer can swell with the methanol in the reformer chambers in combination with internal methanol reforming; FFKM is expensive; silicone is converted from phosphoric acid decomposed from the HTPEM fuel cell MEAs; EPDM has too low temperature resistance for HT-PEM fuel cells). The expanded graphite also serves to reduce the contact resistance of the reformer chambers (hard plate on hard plate would result in high electrical contact resistance and would therefore mean high power loss). Expanded graphite is inexpensive both as a raw material and in processing (e.g. stamping).

If internal reforming is used in reformer chambers in a fuel cell stack, the heat transfer elements or temperature control elements can ideally be used both to seal off the reformer chambers and to cool the cells.

If the heat transfer elements are made of expanded graphite (e.g. to reduce the contact resistance), sealing the media using sealing rings on the expanded graphite is associated with disadvantages, since both elements (both the sealing ring and the expanded graphite) have a flexible character and a local plastic deformation of the expanded graphite and creep or settling of the two elements can occur over time. If sealing rings are used as sealing elements, they should therefore advantageously not rest on expanded graphite, which is structurally difficult or impossible, especially in connection with internal reforming, since the reformer space is designed over a large area in the supply plate and an interruption in the heat conduction element for a sealing track for the Heat conduction would be disadvantageous.

The additional function of the heat conduction element or the temperature control element as a sealing element is therefore associated with many advantages.

The temperature control element, the temperature control rib and/or the thermally conductive element can also be made of another suitable thermally conductive material, such as metal or a carbon-polymer compound. In this case, the media can be sealed with elastomer or expanded graphite, for example.

The plate-shaped tempering ribs can be provided with tempering bodies to increase the surface area of the tempering ribs in order to increase the convective heat transfer. The tempering bodies can be made of another heat-conducting material, such as graphite, ceramic or metal. These temperature control or cooling bodies can preferably be made of aluminum. The tempering bodies enlarge or increase the heat transfer from the tempering ribs to the air.

The temperature control bodies can be designed, for example, as aluminum heat sinks, graphite elements, heat pipes, heat-conducting ceramics, snap-in elements, rivet elements, metal clips, spring elements, metal clamps or as bent metal parts.

The tempering bodies can be fastened or connected to the tempering ribs, for example by spring force, gluing, clamping, screws or rivets.

For example, resilient bent/pressure-formed steel, copper, brass or aluminum parts can be clamped to the tempering ribs as tempering bodies. The spring force ensures good heat transfer between the air guide element and the temperature control body.

In one embodiment, individual tabs of a plate-shaped temperature control body (e.g. made of copper-containing metal) can rest alternately on one side and the other side of an air guiding element and thus create a heat-conducting connection to it with spring force and form a large heat transfer surface to the air due to the curved design.

In a further embodiment, for example, extruded aluminum heat sinks can be riveted, clamped or screwed as temperature control bodies to temperature control ribs.

If the temperature control elements, temperature control ribs and/or temperature control bodies are designed to be electrically insulating, they can contact several temperature control elements, temperature control ribs and/or temperature control bodies arranged one after the other in the temperature control direction. In this way, heat exchange or equalization between these elements is made possible, so that more efficient temperature control of a fuel cell stack with good temperature distribution is possible.

Spacers or structures, in particular resistance elements, can be arranged between two adjacent tempering ribs.

The resistance elements or spacer structures can be provided for positioning or for aligning or for centering the tempering ribs in order to compensate for linear expansion of the fuel cell stack and/or manufacturing tolerances. This is particularly possible if the tempering ribs are made of expanded graphite, which is sufficiently flexible and can be bent easily.

The resistance elements or spacer structures can extend orthogonally to the temperature control ribs, can be used for positioning and/or spacing of temperature control ribs and can, for example, prevent large gaps between adjacent temperature control ribs, for example due to unintentional bending of temperature control ribs during assembly or due to thermal expansion the compo Description of the fuel cell stack in operation. Such gaps would increase the boundary layer thickness for the heat transfer and thereby possibly have a negative effect. Gaps between tempering ribs that are too small can also be avoided with the help of spacer structures.

The spacer structures can also serve to prevent electrical contact between adjacent temperature control ribs if the temperature control ribs are designed to be electrically conductive.

The resistance elements can be arranged in particular to influence the air flow between the tempering ribs.

The resistance elements or the spacer structures can serve or be provided to influence the flow of the temperature control air, for example in order to form a turbulent flow. For this purpose, the spacer structures and/or resistance elements can also have recesses and/or holes for influencing the flow of the tempering air.

The resistance elements or the spacer structures can also serve to specifically influence the pressure loss of the air flow, so that the temperature distribution of the fuel cell stack is more uniform.

For this purpose, the resistance elements or the spacer structures, for example by correspondingly smaller cutouts or openings or smaller distances to tempering ribs locally on specific cells, can aim for a higher pressure loss at a given volume flow in contrast to the cutouts on other cells. The differential pressure between air supply and air discharge can also be increased overall by the spacer structures or resistance elements at a given volume flow (for example by correspondingly small flow cross sections on the spacer structures or resistance elements) in order to influence the temperature distribution of the fuel cell stack in the desired way and/or to make it less sensitive to tolerances in the air flow or other parameters that lead to a deviation in the pressure loss.

If the distance between resistance elements or spacer structures and temperature control ribs should be approximately constant for a defined flow cross section (e.g. also when the fuel cell stack with the temperature control elements expands when heated), elements can be formed or attached to the spacer structures or resistance elements to keep the distance.

The resistance elements or the spacer structures can be formed, for example, from the material mica or micanite or from ceramic or glass fiber plate. Furthermore, they can be made of metal or expanded graphite, for example, and they can have an electrically insulating coating.

The temperature control ribs can also have the function of temperature control bodies and/or resistance elements, or temperature control bodies and/or resistance elements can be integrally formed on the temperature control ribs. The tempering ribs can form a plurality of tempering channels that extend in and/or transversely to the tempering direction.

In this way, depending on the geometry of a fuel cell stack, a homogeneous temperature distribution can be achieved by providing the multiple temperature control channels.

Furthermore, a fuel cell stack with such a temperature control device is provided according to the invention. This comprises several fuel cells connected in series, which form the roughly cuboid fuel cell stack, wherein at least one side wall or preferably two, in particular opposing, or three or four side walls are provided with a temperature control device as described above.

The advantages that can be achieved in this way have been shown above with reference to the temperature control device and apply analogously to a fuel cell stack provided with such a temperature control device.

The invention is explained in more detail below with reference to the drawings. These show in:

1 shows a schematic, perspective view of a first exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

2 shows a schematic, perspective representation of a second exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

3 shows a schematic perspective view of a third exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

4 shows a schematic, perspective view of the temperature control device according to the invention from FIG. 3,

5 shows a schematic, perspective representation of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

6 shows a schematic, perspective representation of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

7 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

8 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

9 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

10 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

11 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention,

12 shows a schematic, perspective illustration of a further exemplary embodiment of a fuel cell stack with a temperature control device according to the invention, 13 shows a schematic exploded view of plate-shaped elements of a fuel cell stack, and

14 is a perspective detailed view of a gas distributor structure from FIG. 13.

A fuel cell stack 2 is described below by way of example, which is provided with a temperature control device 1 according to the invention (FIGS. 1 to 3 and 5 to 12).

The fuel cell stack 2 with internal reforming is designed similarly to the fuel cell stack described in WO 2015/110545 A1. In this document, the full content of which is hereby referred to, a fuel cell system for thermally coupled reforming with reformate processing is described. This system comprises a fuel cell stack with an anode inlet, an anode outlet, a cathode inlet and a cathode outlet, and a reformer device for steam reforming thermally coupled to the fuel cell stack for providing an anode fluid comprising reformed fuel, which is upstream of the anode inlet. The fuel cell stack and the reformer device are thermally coupled in such a way that the waste heat from the fuel cell stack is transferred to the reformer device by means of thermal conduction and is at least partially used to operate the reformer device, and at least one treatment device arranged between the reformer device and the anode inlet for removal and/or or reforming of non-reformed fuel and/or substances harmful to the fuel cell stack from the anode fluid is provided, wherein an operating temperature of the fuel cell stack is in the range between 140° C. and 230° C.

The fuel cell stack 2 is designed as an HT-PEMFC (high-temperature polymer electrolyte fuel cell). This high-temperature fuel cell works in a temperature range of 160 °C -180 °C or up to 230 °C. The required hydrogen is obtained from methanol through an internal and an external reforming process and converted into electricity in the fuel cell stack.

In principle, the temperature control device 1 according to the invention can be used with all types of devices described above, in particular fuel cell stacks.

According to a first exemplary embodiment, a corresponding fuel cell system (not shown) comprises the fuel cell stack 2 with an anode inlet 3 and an anode outlet 4 and a cathode inlet 5 and a cathode outlet 6.

Furthermore, a reformer device 7 thermally coupled to the fuel cell stack 2 for providing reformate or anode fluid is provided, which is connected upstream of the anode inlet 3 and a processing device (not shown) arranged outside the cell stack between the reformer device 7 and the anode inlet 3 for removal of unprocessed fuel and harmful substances from the reformate.

In the following, a structure of a "repetition unit" 8 is explained by way of example, which in the present case describes two cells of a fuel cell stack 2 composed of several cells. First, a plate-shaped temperature control element 9 of the temperature control device 1 is provided.

This temperature control element 9 is formed from a plate-shaped temperature control rib 10 and a plate-shaped heat conduction element 11 integrally formed thereon.

Since the heat conduction elements 11 can be arranged between individual cells of a fuel cell stack 2, the plate-shaped temperature control ribs 10 are mechanically coupled to the fuel cell stack 2 in such a way that the temperature of the fuel cell stack 2 is controlled via the plate-shaped heat conduction elements 11 by means of heat conduction, and the plate-shaped temperature control ribs 10 are temperature-controlled by inflow or application of tempering air by means of convection.

The reformer device 7 connects to the temperature control element 9 .

The reformer device 7 is integrated into a supply plate 17 of a fuel cell stack 2 . One side of the supply plate is provided with a meandering distribution structure, called a flow field, for an anode fluid (or correspondingly for a cathode fluid).

A reformer chamber of the reformer device 7 is formed on the side of the supply plate opposite the distributor structure for the anode fluid. Such a plate is referred to below as a reformer monopolar plate with a reformer chamber or as a monopolar plate with a reformer space.

The reformer chamber has an inlet for supplying the carrier gas containing gaseous fuel and an outlet for discharging the reformate formed from the gaseous fuel and the carrier gas. A reformer catalyst (not shown) is arranged in the reformer space and is distributed evenly over the entire reformer space. A barrier, e.g. in the form of a network made of the material PEEK or channels or webs, is formed between the inlet or outlet and the reformer chamber, which prevents the reformer catalyst from escaping from the reformer chamber into the inlet and outlet when the system is moved. Furthermore, in the reformer chamber there are, for example, cuboid bodies or webs from the supply plate in order to ensure an even distribution of the reformer catalyst and the gas. These also serve to form an electrically and thermally conductive connection between the supply plates and to ensure the mechanical stability of the supply plates and thus of the fuel cell stack.

The anode fluid distribution structure is followed by one or more sealing elements, gas diffusion layers, catalyst layers, and an electrolyte-containing membrane (membrane-electrode assembly, MEA).

This is followed by a supply plate, which is provided on both sides with distribution structures that are spatially separated from one another, for example that run in a meandering manner. One side has a cathode fluid manifold structure and the other side has an anode fluid manifold structure. Such a plate is referred to below as a bipolar plate. This is followed by one or more sealing elements, gas diffusion layers and catalyst layers as well as a membrane (MEA) containing electrolyte and a supply plate 17 as a monopolar plate with cathode flow field. This completes the construction of the repeating unit comprising a temperature control element 9 and two cells.

By arranging several repeating units 8 in a row, a fuel cell stack 2 with any number of cells, depending on the desired output, can be formed.

According to a first exemplary embodiment (FIG. 1), the temperature control air duct 12 comprises at least the temperature control channel 15, which essentially extends in a temperature control direction 16 and whose cross section decreases or tapers conically in the temperature control direction 16, so that individual cells of the fuel cell stack 2 are heated approximately evenly. or can be cooled.

A plurality of plate-shaped tempering ribs 10 are arranged approximately orthogonally to a side wall 14 of the fuel cell stack 2 and are thermally coupled to it. The tempering ribs 10 have recesses 13 that are axially aligned in the tempering direction 16 .

In the recesses 13 of the temperature control ribs, plate-shaped temperature control air guide elements 10 are provided, which are arranged at a predetermined angle relative to the side wall 14 of the fuel cell stack 2 and delimit a temperature control channel 15 of the temperature control air duct 12 . The angle can be, for example, at least 25° or 30° or 40° or 50° or at most 70° or 80° or 90° and preferably at most 60°

The temperature control channel 15 is delimited by recesses 21 formed in the temperature control air guiding elements 20, a side wall 14 of the fuel cell stack 2 and a housing (not shown) surrounding the fuel cell stack. The housing can be provided with thermal insulation.

In order to be able to optimally dissipate the heat from the fuel cell stack 2, the temperature control device 1 with its temperature control elements 9 and a corresponding fan device (not shown) for applying a temperature control medium (preferably air) to the at least one temperature control channel 15 is provided within the scope of the present invention.

The temperature control device 1 has at least one or two or three or four or five or six or seven or eight or more main temperature control channels 22 . The main temperature control channels 22 are preferably arranged at equal distances from one another in the lateral direction and are arranged mirror-symmetrically or symmetrically along a casing wall or along the side walls 14 of the fuel cell stack 2 .

In addition, a temperature control air supply 23 is provided, which is also part of the temperature control air duct 12 .

The temperature control elements 9 can also be designed as a thermally conductive seal in order to seal off individual components or functional units or repeat units 8 of a fuel cell stack 2 . This seal can be, for example, a graphitic material with sufficient thermal conductivity, or in the case of a metallic fuel cell stack 2, a corresponding metallic seal.

In an alternative embodiment of the invention, it can be provided to integrate an anode and/or cathode distributor structure into the heat conduction elements 11 or to form corresponding components (e.g. heat conduction element and cathode and/or anode monopolar plate) in one piece. The temperature control element can, for example, additionally assume the functions of the supply plate(s) (among other things, the gas distribution or fluid supply of a fuel cell MEA).

A gas distributor structure (flow field) can be pressed into a temperature control element, which is made of a deformable material and has at least one temperature control rib (FIGS. 13 and 14). This has several advantages: on the one hand, one monopolar plate or one bipolar plate can be saved, which leads to cost advantages (the plates with channel structure are expensive), on the other hand, sealing surfaces can be saved and the risk of leaks and costs for sealing materials can be reduced. Furthermore, there is a lower thermal gradient, since no heat transfer from a monopolar plate or bipolar plate to the temperature control element is necessary for the heat transfer. As a result, better temperature distribution and lower energy consumption for cooling can be achieved. In addition, the fuel cell stack becomes shorter because fewer plates are required. Good heat conduction within the heat conduction element is also ensured with pressed-in channels, which is due, among other things, to the fact that pressing or rolling channel structures into the temperature control element does not reduce the amount of material (but only more strongly compresses it) compared to, for example, a machining. In addition, it is possible to dispense with seals. In this way, the temperature control element can also fulfill the function of the MEA seal. For example, a temperature control element made of a deformable material and a plate or a temperature control element made of a non-deformable material can adjoin a membrane electrode unit (MEA).

Two plates or temperature control elements made of a deformable material can also adjoin the MEA and thereby seal the MEA from both sides, for example. Another advantage is that the plates with embossed supply channels can be produced more cheaply, since embossing channels in flat material can be cheaper than, for example, milling channels from a plate or manufacturing them by injection molding or compression molding.

One or more plates, in which channels are pressed and which, among other things, fulfill the function of a monopolar plate or bipolar plate, can be provided in the cell stack.

The material of the plates, heat conduction elements, tempering ribs or tempering elements into which structures or channels are pressed can be expanded graphite, for example, which is obtained as a flat plate and into which structures or channels are introduced by rolling, hammering, embossing or pressing. The embossing of the channels can also be accompanied or implemented by a stamping and forming process. The material is preferably electrically conductive and can have a material thickness of, for example, 1 to 4 mm, preferably 1.5 mm, 2 mm, 2.5 mm or 3 mm, so that with high mechanical Pressure can emboss channels with channel depths of more than 0.2 mm, preferably more than 0.6 mm, and so that at the same time next to and/or opposite the embossing either no elevations or elevations with a height of less than 0.4 mm, preferably less than 0 ,1 mm. The thermal conductivity of the heat conduction element or temperature control element is over 50 W/mK, preferably over 100 W/mK or over 150 W/mK. The material does not necessarily have to contain a binder or plastic (eg thermoplastic or hardening resin), but can (in contrast to injection molding or compression molding) consist of more than 99 percent carbon, for example. Graphite with a concentration of over 99% is chemically and thermally more stable than carbon-plastic compounds, which is advantageous for a long service life. The channels or structures can be pressed in, for example, at temperatures below 100.degree. C., preferably below 40.degree. The pressure for embossing structures or channels can be more than 10 MPa, preferably between 15 and 300 MPa. The specific electrical resistance (in the through-plane direction) of the material of the temperature control element or heat conduction element is less than 0.1 ohm*cm, preferably less than 0.04 ohm*cm or less than 0.02 ohm*cm. A conventional fuel cell bipolar plate material made of a carbon-polymer compound would be very brittle, fragile and solid with this low specific resistance, so that no channels could be embossed at temperatures below 100 °C. For this reason, a deformable material such as expanded graphite, which is commonly used for flat gaskets in flanges, must be used. The structures or channels can be embossed into the plate either on one side or on both sides. If necessary, the plates, temperature control elements or heat conduction elements can be chemically or physically treated, impregnated or coated in order to avoid heavy absorption of electrolyte, for example from a fuel cell MEA, and the electrical resistance to the MEA must be less than 50 mOhm/cm ² . The embossing of structures in the tempering ribs can serve, for example, to increase the heat transfer to the air or to another material. For example, a metallic frame, which serves as a temperature control rib, can be contacted to a heat conduction element that contains embossed channels. The metallic frame or a metallic molding or a thermally conductive plate can be attached, for example by clamping, to the thermal element, which contains embossed channels. Thermal contact can also be achieved by soldering or welding material to the inner edges of the metal frame, so that a positive and/or non-positive fit is created with the temperature control element or heat conduction element, and it can be provided that areas of the metal sheet are inserted into the deformable temperature control element or .Press in the heat conduction element. If a reformer chamber is adjacent to the plate with embossed supply channels, there can be better heat transfer from the MEA to the reformer chamber, since there is no monopolar plate or bipolar plate between the MEA and the reformer chamber, only a heat-conducting element, for example.

A fuel cell stack can thus be provided which is characterized in that one or more heat conduction elements and/or temperature control elements are made of a material, preferably "expanded graphite". The material is deformable at a temperature of below 80° C. In addition the material has an electrical specific through-plane resistance of less than 0.1 Ohm*cm In particular, channel structures for a fluid supply are formed in the heat conduction elements and/or the temperature control elements, which are produced by embossing in the deformable material. In order to ensure that the heat generated is transported away, an air flow is provided around the stack, which removes the excess heat from the system. The excess heat can also be used as waste heat.

The fuel cell stack can also be combined with one or more other cell stacks. For example, a reformer stack may be attached or braced to the fuel cell stack. In this case, the temperature control device can be designed either on the combination of stacks or separately for each stack.

Unless otherwise described, all the embodiments of the present invention have the same technical features. The technical features of the individual exemplary embodiments can be combined with one another in almost any way.

According to a second exemplary embodiment (FIG. 2), the plate-shaped tempering ribs 10 of the tempering elements 9 are provided with tempering bodies 19 to increase the surface area of the tempering ribs 10 in order to increase the convective heat transfer.

According to a third exemplary embodiment (FIG. 3) of the temperature control device 1 according to the invention, the temperature control ribs 10 are not connected in one piece to the heat conduction elements 11, but are formed separately from them. Within the scope of the present invention, tempering air guide elements 20 can also be provided at these tempering ribs 10 .

Similar to the first and second exemplary embodiment, the temperature control ribs 10 have recesses 13 which form a temperature control channel which tapers in the temperature control direction 16 .

The individual temperature control ribs 10 are connected to one another via resistance elements 18 which extend transversely to the temperature control ribs 10 and run approximately in the temperature control direction. The resistance elements 18 serve as spacers and have corresponding recesses 25 for the passage of the tempering air flow.

The advantage of such a temperature control device is that it can be attached to a side wall, for example of a fuel cell stack, in a simple manner (FIG. 4).

Such a temperature control device 1 is advantageous in that the narrowing flow cross sections on the temperature control ribs promote the flow towards the fins by reducing the air boundary layer.

In a further exemplary embodiment (FIG. 5) of the temperature control device according to the invention, the temperature control ribs 10 again have recesses 13 which taper in the temperature control direction 16 . In addition, for spaced arrangement and for changing the air flow, resistance elements 18 are arranged as spacers between the individual tempering ribs. In particular, the edge regions of the tempering ribs 10 have passage openings 24 that increase in the tempering direction 16 .

As a result of the passage openings 24 enlarging in the temperature control direction, the largest possible surface area of the temperature control ribs 10 can be realized in the air discharge despite the small installation space. The less air has to be discharged orthogonally to the respective temperature control rib, the smaller the recess in the temperature control rib and the pressure loss of the outflowing air flow is only slightly higher than if all temperature control ribs had recesses of the same size. Furthermore, the size of the recesses can serve to distribute the volume flow.

In addition, resistance elements 18 are provided between the tempering ribs 10 . The resistance elements 18 can be formed like a comb. Micanite (mica) can preferably be used as the material. These also serve to reduce the air boundary layer, in particular due to a narrow gap provided between the resistance elements 18 and the tempering ribs 10 . They also contribute to the formation of turbulence and vortices and thus to an increase in pressure loss. A higher pressure drop favors a more even pressure distribution over the entire fuel cell stack.

According to a further exemplary embodiment (FIG. 6), the tempering ribs 10 are offset from one another in the tempering direction 16 . A blower device (not shown) first acts on a temperature control channel 15.1 that tapers in the temperature control direction, with the temperature control air then flowing along the temperature control ribs into a temperature control channel 15.2 that widens in the temperature control direction 16.

According to a further exemplary embodiment of the temperature control device 1 (FIG. 7), corresponding temperature control ribs 10 are provided on two opposite sides of a fuel cell stack 2 .

On one of the walls of the fuel cell stack 2 arranged between the two side walls that are provided with temperature control ribs, a temperature control air guide element 20 is provided that is inclined relative to the temperature control direction and forms a temperature control channel 15 that tapers in the temperature control direction. The technical effect of such a temperature control channel corresponds approximately to the temperature control channels 15.1, 15.2 shown above, which taper in the temperature control direction.

In a further exemplary embodiment of the temperature control device 1 according to the invention (FIG. 8), provision is also made for the temperature control ribs 10 to be formed on two opposite side walls 14 of the fuel cell stack 2 .

Furthermore, 10 resistance elements 18 are provided between the tempering ribs. These have recesses 25 which extend into the temperature control channels 15 formed between the temperature control ribs 10 . The diameter of the recesses 25 preferably increases from the center of a corresponding fuel cell stack 2 to the outer edge regions. In addition, two tempering air guiding elements 20 are provided which are approximately roof-like or inclined relative to a side wall of the fuel cell stack 2 . These are arranged approximately centrally spaced from each other. It is provided here that a blower device (not shown) introduces the temperature control air into a free space between the two temperature control air guide elements 20 . The temperature control air is then distributed via the corresponding recesses 25 into the temperature control channels 15 formed between the temperature control ribs 10, so that a uniform temperature control of a fuel cell stack 2 is again possible.

According to a further exemplary embodiment of the temperature control device according to the invention (FIG. 9), temperature control ribs 10 are provided on two opposite sides 14 of the fuel cell stack 2 .

Two tempering air guiding elements 20 are arranged on a further side wall 14 , which essentially extend parallel to this side wall 14 and form a tempering air feed 23 and part of a tempering air duct 12 .

The temperature control air reaches the region of the temperature control ribs 10 via the spaced arrangement between the two temperature control air guide elements 20 . It is provided here that the temperature control ribs 10 delimit a temperature control channel 15 which tapers towards both end regions of the fuel cell stack 2 .

Furthermore, a resistance element 18 is provided for holding the temperature control ribs 10 at a distance, which is arranged transversely to the temperature control ribs 10 and has recesses 25 in the region of the temperature control ribs 10 for the passage of the temperature control air.

In a further exemplary embodiment of the temperature control device (FIG. 10), temperature control ribs 10 are again provided on two opposite side walls 14 of the fuel cell stack 2 .

In addition, at least one resistance element 18 or spacer element for holding the temperature control ribs 10 at a distance is provided on each side, corresponding recesses 25 being formed in the resistance elements 18 in the region of the temperature control ribs 10 . Several such resistance elements 18 can also be provided.

Because the resistance elements have recesses 25 that increase in size in the direction of the edge regions of the fuel cell stack and a temperature control air guide element is provided, which is inclined relative to a side wall of the fuel cell stack 2 in such a way that there is a larger spacing between the temperature control air guide element 20 and the fuel cell stack in the area of a temperature control air inlet is formed, a temperature control channel 15 that tapers transversely to the temperature control direction 16 is formed, with the temperature control channel 15 or a corresponding temperature control air duct 12 also comprising the corresponding intermediate spaces between the temperature control ribs.

The provision of recesses 21 of different sizes in the resistance elements 18 again makes it possible to control the temperature of a fuel cell stack 2 uniformly. According to a further exemplary embodiment of a temperature control device 1 according to the invention (FIG. 11), no individual temperature control ribs 10 are provided. A large temperature control body 19 which extends essentially over the entire side wall 14 of a fuel cell stack 2 and includes the temperature control ribs 10 is provided for contacting the heat conduction elements. A shaft-like temperature control channel 15 which tapers in the temperature control direction 16 and also forms the temperature control air feed 23 is formed by means of a plurality of temperature control air guide elements 20 connected to one another.

In this case, it may also be necessary to insulate the temperature control body 19, which is designed, for example, as an aluminum heat sink, from the fuel cell stack by means of a thermally conductive film in order to avoid short circuits.

According to a further exemplary embodiment of a temperature control device 1 according to the invention (FIG. 12), it is provided that temperature control ribs 10 are provided on two opposite sides 14 of the fuel cell stack 2 .

When heating up the cell stack, the hot air flows through the two tempering air guide elements. The front tempering air guide element primarily serves to distribute the hot air when heating up the cell stack. On the other hand, when cooling the cell stack during operation of the cell stack, air does not flow through the front tempering air guiding element, or only slightly, but primarily the cooling air flows through the rear tempering air guiding element. The front tempering air guide element is primarily used to distribute the hot air (larger recesses in the area of the edge cells due to higher heat requirements at the edge cells due to the high heat capacity of the end plates/bracing components and heat dissipation there if necessary). The rear tempering air guide element primarily serves to distribute the cooling air. The hot air flows in before the front tempering air guide element. The cooling air flows in between the front and rear tempering air guide elements.

Furthermore, resistance elements 18 are provided for holding the temperature control ribs 10 at a distance, which are arranged transversely to the temperature control ribs 10 and have recesses 25 in the region of the temperature control ribs 10 for the passage of the temperature control air, whereby the resistance elements lead the air to the temperature control ribs and/or create turbulence in the serve to increase the heat transfer.

The spacer or resistance elements and, if applicable, the tempering ribs, which are located below the cell stack, also have the function, among other things, of transferring the weight of the cell stack to the housing. The present invention can be combined with a burner system for providing thermal energy. Such a device comprises an evaporator device for evaporating a liquid fuel, a burner air supply device, a burner device for burning a fuel mixture comprising evaporated fuel and burner air in order to provide an exhaust gas flow, a functional device for regulating the thermal energy of the exhaust gas flow, the burner device being in operation provides the thermal energy for the complete evaporation of the fuel in the evaporator device.

The burner system also includes the tertiary air device and a measuring orifice.

The tertiary air device includes a PWM (pulse width modulation) capable centrifugal fan. The PWM enables precise adjustment of the fan speed and thus a controlled flow of the tertiary air. A sensor line provides information about the current fan speed and can indicate a fan failure by means of a logic check.

In addition to cooling the fuel cell, the tertiary fan heats the fuel cell with the hot exhaust air (hot gas flow comprising exhaust gas flow and tertiary air) from the burner device. The fan enables sufficient cooling of a fuel cell stack at every operating point (different power levels).

The fuel cell stack can be formed from structurally identical units, with a unit for example comprising the following components,

Temperature control element (sealing element), monopolar plate (separator plate) with anode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, monopolar plate with cathode flow field, or

Temperature control element (sealing element), reformer monopolar plate with reformer chamber and anode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, monopolar plate with cathode flow field, or temperature control element (sealing element), monopolar plate with anode flow field, MEA, monopolar plate with cathode flow field), or

Temperature control element (sealing element), monopolar plate (separator plate) with anode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, monopolar plate with cathode flow field, or

Temperature control element, reformer monopolar plate with reformer chamber and anode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, reformer monopolar plate with reformer chamber and cathode flow field, or

Temperature control element, reformer monopolar plate with reformer chamber and cathode flow field, MEA, bipolar plate with anode and cathode flow field, MEA, monopolar plate with anode flow field.

The supply plates, monopolar plates, bipolar plates, heat conduction elements or temperature control elements can be made, for example, from a carbon-polymer compound (formed by injection molding, compression molding, extrusion, rolling, embossing), expanded graphite, flexible carbon-containing material or metal be. These can optionally be connected to one another and/or to other components, for example by welding.

The fuel cell stack (stack) can also contain bracing elements (e.g. end plates) as well as gas and power connection elements and insulation plates/foils (e.g. for electrical insulation).

Depending on the structure of the fuel cell stack, the temperature control elements can be designed as sealing elements. However, a sealing effect is not absolutely necessary. If the heat conduction elements are made of metal, for example, then separate seals or sealing frames can also be used.

With normal polymer electrolyte fuel cells, hydrogen generation (internal reforming) integrated into the stack (fuel cell stack) is normally not possible due to the low temperatures. Due to the higher temperatures of up to approx. 200 °C in an HT-PEM fuel cell, however, it is possible to use this process, which is mainly known in the field of SOFC and MCFC.

Corresponding reformer spaces (reaction spaces) can therefore be integrated in the stack in a regularly recurring sequence instead of the cooling plates normally used.

A good temperature distribution of the fuel cell stack (e.g. plus/minus 5 Kelvin) is particularly important when internal reforming takes place in the fuel cell stack. A deviation in the temperature of different reformer spaces within the fuel cell stack of more than 5 Kelvin would result in a significant deviation (for example by more than 10 percent) in the reformer conversion of the internal reforming in the respective reformer space or in the respective reformer chamber. Assuming a conversion of 50% is to be achieved in the fuel cell stack, a deviation in conversion of far more than plus/minus 10 percent would lead to high inefficiency of the internal reforming in some reformer spaces and the reformer spaces or reformer catalyst quantity would have to be designed larger.

Assuming a conversion of more than 98% is to be achieved in the fuel cell stack in order to save on post-cleaning or post-reforming, falling below the target conversion by far more than 10 percent would damage the fuel cell stack in some reformer rooms if for the fuel cell harmful substances, such as methanol, are conducted to the fuel cell anodes of the cells.

The internal reformer spaces or the amount of reformer catalyst would therefore have to be designed significantly larger (e.g. by more than 50 percent) if the temperature distribution was uneven than if the temperature distribution of the fuel cell stack was uniform, which would have a significantly negative impact on the costs and/or the required installation space.

Furthermore, hotter reformer chambers would result in a higher carbon monoxide concentration in the product gas, which negatively affects the performance of the cells by poisoning the catalyst surface of the fuel cells. In an advantageous embodiment, the reformer chambers are connected to one another by an inlet and outlet which is integrated into the fuel cell stack but is spatially separate from the anode port and cathode port and must be sealed off from the outside.

The temperature control elements or their plate-shaped heat conduction elements can preferably be used to seal the reformer chambers.

A suitable reaction accelerator is used to accelerate the reaction taking place in them. In an advantageous embodiment of the invention, this is a copper catalyst which is in the form of pellets or one or more shaped bodies.

The endothermic reaction described above contributes to the cooling of the stack if heat exchange takes place as a result of the integration of the reaction spaces into the stack. However, cooling the stack by such a process alone is not sufficient. Therefore, the temperature control device according to the invention is required.

The temperature control device can also be used for fuel cell stacks without internal reforming.

One or more temperature sensors can be provided in the fuel cell stack. These can be located, for example, in the middle of the fuel cell stack as well as at the start row and at the end row. The temperature sensors can be, for example, thermocouples that are positioned centrally adjacent to the respective cell. The temperature sensor can be integrated into a heat conduction element, for example it can be pressed into a slot in the heat conduction element. On the first and last cell, the temperature sensors can also be located in the outer area, i.e. not in the area of the center of the cell, in order to be able to approximately map the minimum temperature of the fuel cell stack during heating.

The setpoint temperature of the fuel cell stack during fuel cell operation can be regulated, for example, using the temperature sensor in the middle of the fuel cell stack or using the mean value of the measured values of several temperature sensors in and/or on the fuel cell stack or using a temperature sensor that makes thermal contact with a temperature control element from the fuel cell system via the blower device.

A thermocouple for measuring the temperature of the fuel cell stack can be coupled to at least one temperature control element. The temperature of the fuel cell stack can be measured in any operating state using the thermocouple. The temperature control device can be regulated accordingly in order to set the desired temperature in the fuel cell stack.

For an approximately uniform temperature distribution within the fuel cell stack (e.g. with a hundred cells) during fuel cell operation, it is usually necessary, especially on the cells not located near the start or end row (e.g. not on the first four or last four cells), a approximately the same heat flow is required from each individual cell to the cooling air or from the heating air to each individual cell. The heat flow has the unit watt.

It is assumed here that all cells of the fuel cell stack generate approximately the same waste heat during operation under the same conditions, for example due to approximately the same potential with a given electrical current flow through all cells (same power of all cells). The waste heat and thus the heat flow to be dissipated by the individual cells under the same conditions should vary by less than plus/minus seven percent from the mean value. If this is not the case due to higher output fluctuations of the fuel cell units, then different heat flows would be necessary for an even temperature distribution of the cells (for example, more than plus/minus seven percent deviation of the heat flow).

In addition, during fuel cell operation, the gas flow of the media within the fuel cell stack (for example in the manifolds or flow fields) can also have a minor influence on the heat flows and/or the temperature distribution. For example, the cathode air in the manifold warms up from the first to the last cell or from the last to the first cell. This can be taken into account with the airflow.

The transfer (e.g. via thermal radiation, convection, thermal conduction) of heat from the fuel cell stack to the air outside the temperature control device or to components that are not part of the temperature control device can, as far as it makes sense, be taken into account by the air flow of the temperature control device.

The removal or supply of heat from individual cells or to individual cells of the fuel cell stack can take place either through direct thermal contact of the respective cells to one or more heat conduction elements) or indirectly via heat conduction through one or more adjacent cells and/or via components (e.g. spacer structures , Resistance elements, heat sinks, temperature control bodies, air guiding elements) from or to one or more temperature control element(s) or temperature control ribs.

When heating up the fuel cell stack, a somewhat higher heat flow would generally be required for the start row and the end row of the fuel cell stack to achieve the same temperature as in the middle of the fuel cell stack, since the components required for bracing in the area of the start row and the end row are such as For example, aluminum end plates have a high heat capacity, which has an influence on the temperature of the outer cells of the fuel cell stack when the cell stack heats up due to heat conduction.

On the other hand, when the fuel cell stack is operated at the operating temperature in equilibrium, the outer cells (e.g. the start row and the end row) would have to be cooled somewhat less (less heat flow to the cooling air) than cells in the middle of the fuel cell stack, since heat transfer (e.g. by convection or radiation) from the components required for bracing, such as aluminum end plates, to the air, which affects the temperature of the outer cells of the fuel cell stack. In order to reduce this influence, the end plates can be provided with insulating plates directed towards the cells and/or with insulating material directed towards the surrounding or surrounding air.

These influences (edge effects) on the outer cells can be different in absolute value when cooling during operation than when heating up when starting.

In order to take into account these edge effects, which would have to be compensated for by different airflow to achieve an even temperature distribution on the one hand when cooling during operation and on the other hand when heating up, appropriate devices such as bimetal, shape memory alloy or electrically controlled flaps, baffles can also be used , Guide elements or drawers can be provided, which allow a different flow of the tempering elements during heating than during fuel cell operation.

Hot air for heating and cooling air for cooling the cell stack can be supplied via the same blower (or fan) (e.g. heating device between blower and cell stack). In an alternative embodiment, one or more separate fans are used to supply the hot air and one or more separate fans are used to supply the cooling air. In a further embodiment, the hot air from one or more separate fans and the cooling air from one or more separate fans can be mixed at least partially before reaching the tempering ribs.

When supplying hot air when heating and supplying cool air when cooling the cell stack via the same blower (or fan) without additional controlled elements, the problem arises that with optimal temperature distribution during fuel cell stack operation, on the other hand, poor temperature distribution prevails during heating of the fuel cell stack and thus a longer heating-up time to reach the minimum temperature of the cells for the start of operation results (negative for the fuel cell system start time). The reason for this is that when cooling the fuel cell stack, there is a different cooling requirement in the various areas of the cell stack than the heat requirement when heating the cell stack (e.g. when heating up, there is a particularly high heat requirement at the edge cells).

The advantage of using separate blowers for supplying the hot air to the cell stack is that when the cell stack is heated up, the edge cells (e.g. first and last cell) require more heat output and thus more hot air volume flow and/or temperature than the central areas of the cell stack (due to higher heat capacity of the end plates of the cell stack and/or high heat dissipation at the end plates, e.g. due to insufficient insulation), the edge cells usually require less heat dissipation during fuel cell operation during cooling than the middle areas of the cell stack and thus during the heating-up phase via separate blowers for the supply of hot air the areas of the cell stack that require more heat (e.g. edge cells) can be heated more (e.g. higher temperature and/or higher hot air volume flow). Another advantage of the separate design of fans for heating and fans for cooling the cell stack can be that the cooling air volume flow required for fuel cell operation does not have to flow through the heating device, resulting in a lower pressure loss and thus a lower power requirement of one or more during fuel cell operation active fan can be achieved. In one embodiment, it can be provided that, for the purpose of heating the cell stack, other tempering air guide elements, resistance elements, perforated plates or guide plates are primarily flown with air than for cooling the cell stack. One or more blowers for heating the cell stack can flow against specific temperature control air guide elements (e.g. plates with larger recesses in the area of the edge cells of the cell stack) and another one or more blowers for cooling the cell stack can flow against certain other temperature control air guide elements (e.g. plates with smaller or equally large recesses in the area the edge cells of the cell stack). It is also possible for the air to flow through the tempering air guide elements, which are provided for heating or cooling, one after the other. For example, the air for heating the cell stack can first flow through the temperature control air guide element, which primarily serves to distribute the hot air, and then flow through the temperature control air guide element, which primarily serves to distribute the cooling air. In this case, for example, the tempering air guiding element that flows later can have recesses with a larger total cross section than the tempering air guiding element that flows earlier, in order to influence the flow distribution on the tempering air guiding element that flows earlier as little as possible. Instead of the tempering air guiding element which is flown against later, its function can also be fulfilled by the resistance elements on the tempering ribs.

If the same blower (or fan) is used both to supply hot air when heating and cool air when cooling the cell stack (e.g. to minimize the number of blowers), the different volumetric flow rates to certain areas of the cell stack can also be controlled/regulated by one or more Air routing elements such as flaps, valves or sliders (e.g. two perforated plates with holes of different sizes that can move on top of each other) can be implemented.

If one or more fans are connected to the temperature control device and there is hot air inside the temperature control device (e.g. when heating the cell stack with hot air or due to waste heat from the cell stack), hot air flowing into a fan can damage it. To avoid the flow of hot air into one or more blowers, one or more blowers or fans can be preceded or followed by non-return flaps or corresponding devices that prevent hot air from flowing into the blower or fan. Alternatively or as a support, the blower or fan in question can be operated at a specific speed (formation of back pressure and/or slight cooling air volume flow) in order to prevent hot air from flowing into the blower. This can be monitored by a temperature sensor (e.g. thermocouple), which is connected downstream of the blower, for example, so that the maximum permissible temperature at the blower is never exceeded and damage to the blower is avoided. In particular, when hot air and cooling air are supplied to the temperature control device separately by separate fans, one of the measures described must be used to prevent the hot air from flowing into the fan that is used to supply cooling air to the temperature control device.

In the course of the air flow in the temperature control direction from a first cell of the fuel cell stack to a last cell of the fuel cell stack, the air which flows in the temperature control direction in the temperature control channel can already heat up somewhat during operation of the fuel cell stack due to heat transfer from the temperature control elements to the air flowing past ( for example by five degrees Celsius). In fuel cell operation in equilibrium, it is therefore possible that warmer cooling air arrives at the temperature control element near the last cell than at the temperature control element near the first cell.

Accordingly, it is possible during heating that colder heating air arrives at the temperature control element near the last cell (due to the heat transfer from the air in the temperature control channel to several temperature control elements) than at the temperature control element near the first cell.

This can be taken into account and/or compensated for, for example, by appropriate air routing (ie by the distribution of the volume flow/mass flow) or by the design of the temperature control elements, temperature control bodies and/or resistance elements.

If the cooling air or heating air (temperature control air) comes from a fan device or a heating device, the design of the duct within the fan device or the heating device can have a significant influence on the air distribution on the fuel cell stack. This can be the case, for example, if the air flow at the outlet from the blower device or heating device is not directed exactly in the temperature control direction of the fuel cell stack. Furthermore, the speed distribution of the gas particles within the channel or the flow pattern (turbulent, laminar) can play a role. The flow guidance within the fan device or heating device or, for example, flow breakers or deflections can also have an influence on the air distribution to the cells of the fuel cell stack or cell stack.

In order to ensure good removal of the heat generated, it is possible for cooling bodies to be attached to one or more side surfaces of the stack or fuel cell stack in order to increase the exchange surface. These heat sinks can be, for example, prefabricated heat exchangers or cooling profiles/heat sinks. In this variant, the temperature control elements can, for example, end flush with one or more side surfaces of the fuel cell stack, with one or more large-area aluminum heat sinks being in thermal contact with the fuel cell stack. The ribs of the aluminum heat sink can serve as temperature control ribs.

The heat sinks can be thermally connected to the stack or fuel cell stack with heat-conducting foil. For example, bent aluminum sheets tapering at an acute angle can serve as air ducts.

The thermally conductive foil and/or anodizing of the aluminum can serve here, among other things, for electrical insulation in order to possibly avoid a short circuit across several cells.

Channels and/or lines for conducting one or more fluids (for example for heat transfer from or to this fluid) can be provided in the heat exchanger or heat sink. Lines that carry a fluid can contact the means for influencing the temperature control air flow of a fuel cell stack or be thermally connected to them.

Various types of fuel cells and their respective operating temperatures (BT) are listed below by way of example, which can be heated and cooled (or tempered) in connection with the temperature control device according to the invention. - Alkaline Fuel Cell (AFC); BT: 60°C to 100°C;

- Polymer Electrolyte Membrane Fuel Cell (PEMFC); BT: Low Temperature PEMFC: 60°C - 110°C; High-temperature PEM FC: 120 °C -190 °C or up to approx. 230 °C;

- Direct Methanol Fuel Cell (DMFC); BT: 30°C to 130°C;

- Phosphoric Acid Fuel Cell (PAFC); BT: 170°C to 230°C;

- Molten Carbonate Fuel Cell (MCFC); BT: Approx. 650 °C;

- solid acid fuel cell; BT: 200°C to 300°C

- Solid Oxide Fuel Cell (SOFC); BT: 650°C to 1000°C;

The tempering air inlet or inlets are provided for feeding tempering air into the tempering air duct and in particular the tempering channel. The tempering air outlet or outlets are provided accordingly for discharging the tempering air.

The temperature control air inlet(s) and the temperature control air outlet(s) can also be formed by appropriately designed temperature control elements.

The technical features of the exemplary embodiments of the present invention can be combined with one another as desired, insofar as this makes technical sense.

Reference symbols: temperature control device fuel cell stack anode inlet anode outlet cathode inlet cathode outlet reformer device repeating unit temperature control element temperature control rib heat conduction element temperature control air duct cutout side wall, 15.1, 15.2 temperature control channel temperature control direction supply plate resistance element (spacer) temperature control body temperature control air guide element recess main temperature control channel temperature control air supply passage opening recess

Claims

patent claims

1. Temperature control device for temperature control of a stack-like energy store or converter formed from several cells, comprising several plate-shaped heat conduction elements arranged between the cells, wherein the cells are temperature-controlled via the plate-shaped heat conduction elements by means of heat conduction, several temperature-control ribs arranged outside of the cells for changing the direction of flow of the temperature-control air flow, wherein the tempering ribs are thermally coupled to the heat conduction elements, and wherein the plate-shaped tempering ribs are tempered by being subjected to a tempering air flow by means of convection and/or via structural means by means of heat conduction, the means for influencing the tempering air flow and/or for guiding the tempering air being provided, which for Changing a flow direction and / or a flow rate of the temperature control air flow are formed, the means structurally designed in such a way and / or are arranged in such a way that several of the temperature control ribs can be subjected to a volume flow of temperature control air in such a way that a majority of the cells in a cell center can be heated or cooled approximately uniformly, and wherein the means for influencing the flow of temperature control air and/or for guiding the temperature control air is one and preferably two or several of the following components include at least one additional temperature control rib, the shape and/or arrangement of which differs from the shape and/or the arrangement of the other temperature control ribs, and/or at least one resistance element to control the temperature control air flow through local distribution of pressure losses and/or through vortex formation to change, and / or at least one temperature control air guide element for further changing the flow direction and / or the flow rate of the temperature control air flow compared to changing the flow direction and / or the flow rate of the temperature control air flow through the temperature control ribs and / or at least a temperature control body, which is designed as a heat exchanger.

2. Temperature control device according to claim 1, characterized in that the plurality of temperature control ribs assigned to a side wall of the device at least partially have surfaces of different sizes and/or at least partially surfaces of the same size and/or that the temperature control ribs have recesses of different sizes and/or the same size, wherein the cutouts are provided for passing through and influencing the temperature control air flow, and the size of the cutouts increases or decreases in the temperature control direction and/or the temperature control ribs delimit and/or form one or more temperature control air ducts at least in regions.

3. Temperature control device according to claim 1 or 2, characterized in that the resistance elements are arranged in the region of two adjacent temperature control ribs and approximately orthogonally to the temperature control ribs, the resistance elements being approximately plate-shaped and preferably having one or more openings or recesses.

4. Tempering device according to one of claims 1 to 3, characterized in that the or the Temperierluftleitelemente have recesses which form a tapering in the direction of tempering Temperierluftkanal.

5. Temperature control device according to one of claims 1 to 4, characterized in that the or the temperature control body are designed as a heat exchanger device, wherein the heat exchanger device has ribs and / or wherein the ribs of the heat exchanger device are at least partially the temperature control ribs.

6. Temperature control device according to one of claims 1 to 5, characterized in that one or more of the means for influencing the temperature control air flow form a temperature control channel which tapers in the temperature control direction.

7. temperature control device according to one of claims 1 to 6, characterized in that the temperature control ribs are integrally formed on the heat conduction elements.

8. Temperature control device according to one of claims 1 to 7, characterized in that the heat conduction elements have a thickness of greater than 0.9 mm and preferably greater than 1.4 mm.

9. Temperature control device according to one of Claims 1 to 8, characterized in that at least one temperature control air supply is provided for applying a temperature control air flow to one or more of the means in a temperature control direction from a starting row of the cell stack to an end row, and/or at least one temperature control air discharge to the Discharging the temperature control air from the temperature control device, the temperature control air supply and the temperature control air discharge being part of the temperature control air duct.

10. Tempering device according to one of claims 1 to 9, characterized in that the tempering ribs and / or the Temperierluftleitelemente are structurally configured such that the flow resistance of the Temperierluftführung increases in temperature control, and / or that all cells can be charged with approximately the same volume flow (or mass flow) of temperature control air, and/or that the temperature control air guide elements and/or the temperature control ribs delimit in sections at least one temperature control channel, which essentially extends in the temperature control direction and whose cross section decreases in the temperature control direction, and /or that a cross section of the temperature control air duct tapers in the temperature control direction, and/or that the spacer elements are arranged between the temperature control air guide elements and/or the temperature control ribs and approximately orthogonally to them, so that heat transfer surfaces of the temperature control ribs and/or the temperature control bodies and/or the temperature control air guide means in Tempering direction are larger, and / or that the resistance elements are arranged between the tempering air guide elements and / or the tempering ribs, so that a higher heat transfer through the flow of tempering air guide elements and / or tempering ribs with tempering air tion of or to the tempering air guiding elements and/or tempering ribs, and/or that the tempering bodies are arranged on the tempering air guiding elements and/or the tempering ribs, so that a higher heat transfer surface results in better heat transfer from and to the tempering ribs.

11. The temperature control device as claimed in claim 9 or 10, characterized in that the cross sections and/or number of one or more temperature control air inlets and/or one or more temperature control air discharges are matched to one another in such a way that the temperature of a cell stack is approximately evenly controlled and/or that the inflow of the temperature control ribs with the temperature control air flow is automatically regulated and/or controlled on the basis of operating parameters of the cell stack,

12. Temperature control device according to one of claims 1 to 11, characterized in that the temperature control channel is partially delimited transversely to the temperature control direction by the temperature control air guide elements and/or the temperature control ribs, a side wall of a cell stack and a housing surrounding the cell stack.

13. Temperature control device according to one of claims 1 to 12, characterized in that the plate-shaped heat conduction elements form sealing elements of the cell stack.

14. Fuel cell stack comprising a plurality of fuel cells connected in series, which form the approximately cuboid fuel cell stack, wherein at least one side wall or preferably two, in particular opposing, or three or four side walls are provided with a temperature control device according to one of claims 1 to 13, wherein the temperature control device per side wall of the fuel cell stack one or more temperature temperature control air inlets and one or more temperature control air outlets and wherein at least one plate-shaped temperature control air guide element or resistance element is primarily designed to distribute the hot air flow, so that the edge cells of the cell stack are subjected to a stronger flow during heating than the majority of the remaining cells, and/or that at least one plate-shaped temperature control air guide element or resistance - selement is used to distribute the flow of cooling air.

15. Fuel cell stack according to claim 14, characterized in that one or more heat conduction elements and/or temperature control elements have channel structures for supplying fluid to the fuel cell stack, which are produced by stamping.