METHOD FOR OPERATING A HEAT EXCHANGER, AND ENERGY STORE HEAT EXCHANGE SYSTEM

Abstract

Disclosed is a method for operating a heat exchanger and an energy store heat exchange system with an energy store including multiple electrochemical cells for providing electrical energy, with a flow duct for providing the cells with a flow of a heat-exchange medium in a flow direction, wherein the cells are arranged in series in the flow direction, wherein the cells each have a heat-exchange surface around which the heat-exchange medium can be made to flow and through which heat can be exchanged between the heat-exchanging medium and the cell, wherein a first (in the flow direction (S)) cell has a first heat-exchange surface, wherein a second cell, arranged downstream of the first cell, has a second heat-exchange surface, the second heat-exchange surface being larger than the first heat-exchange surface, and with an open- and/or closed-loop control unit for setting the volumetric flow.

Claims

1. A method for operating a heat exchanger for an energy store, comprising the steps of: arranging a plurality of electrochemical cells, arranging a heat-exchanging medium configured for heat exchange flows around the cells one after the other in a flow direction, wherein each of the cells comprises a heat exchange surface configured such that heat exchange between the heat-exchanging medium and a respective cell takes place, wherein a first cell, in the flow direction, is configured to transfer heat via a first heat exchange surface with the heat-exchanging medium, wherein a second cell is arranged downstream from the first cell by means of a second heat-exchanging surface that is larger than the first heat-exchanging surface, and wherein a volume flow of the heat-exchanging medium is set such that, for a selected operating point of the cells, a temperature difference between a temperature of the first cell and a temperature of the second cells is at least one of reduced and minimized.

2. The method according to claim 1, wherein the first cell in the flow direction and the last cell in the flow direction is used as the first cell and as the second cell.

3. The method according to claim 1, further comprising the steps of: detecting a first temperature of the heat-exchanging medium at a first position, detecting a second temperature at a second, downstream position, and on the basis of conditions present at at least one of the determined operating point and the present cell flow, adjusting the volume flow such that a temperature difference of the cells is at least one of reduced and minimized.

4. The method according to claim 1, further comprising the steps detecting a first temperature of a first cell in the direction of current flow and a second temperature of a second cell arranged downstream, wherein the volume flow is adjusted such that a difference between the first temperature and the second temperature decreases.

5. The method according to claim 1, further comprising the steps of controlling the volume flow and/or regulating the volume flow.

6. An energy storage heat exchange system, having an energy storage device, comprising: a plurality of electrochemical cells configured to provide electrical energy, and having a flow channel for supplying the cells with a current of a heat-exchanging medium in the direction of flow, wherein the cells are arranged one behind the other in the flow direction, wherein the cells each have a heat exchange surface around which the heat-exchanging medium can flow and through which heat between the heat-exchanging medium and the cell is exchangeable, wherein a first cell in the flow direction has a first heat exchange surface, wherein a second cell arranged downstream of the first cell has a second heat exchange surface, wherein the second heat exchange surface is larger than the first heat exchange surface, having a control and/or regulating device according to claim 6 and a device for adjusting the volume flow, wherein the control and/or regulating device has the device for adjusting of the volume flow is operatively connected such that the volume flow can be controlled and/or regulated by the control and regulating device, in particular such that a temperature difference between a first temperature of the first cell and a temperature of the second cell is reduced, in particular minimized.

7. The energy storage heat exchange system according to claim 6, further comprising: a first sensor configured to detect a temperature of the heat-exchanging medium and arranged at a first position of the flow channel, and at least one second sensor configured to detect a temperature of the heat-exchanging medium, and wherein temperature detected by the first and at least one second sensors is configured to be supplied by at least one of the control device and the regulating device.

8. The energy storage heat exchange system according to claim 6, wherein the heat-exchanging medium is configured to be guided in a flow circuit which is decoupled from a heat-exchanging circuit for controlling the temperature of a vehicle cabin or an engine.

9. The energy storage heat exchange system according to claim 6, further comprising a at least one of a control device and a regulating device configured to be operatively connected to a device for adjusting volume flow of a heat-exchanging medium.

10. The energy storage heat exchange system according to claim 9, wherein at least one of the control device and the regulating device is configured to regulate the energy storage heat exchange system, the heat exchange system comprising: a heat exchanger configured to store energy store, a plurality of electrochemical cells, wherein the heat-exchanging medium is configured for heat exchange flows around the cells one after the other in a flow direction, wherein each of the cells comprises a heat exchange surface configured such that heat exchange between the heat-exchanging medium and a respective cell takes place, wherein a first cell, in the flow direction, is configured to transfer heat via a first heat exchange surface with the heat-exchanging medium, wherein a second cell is arranged downstream from the first cell by means of a second heat-exchanging surface that is larger than the first heat-exchanging surface, and wherein a volume flow of the heat-exchanging medium is set such that, for a selected operating point of the cells, a temperature difference between a temperature of the first cell and a temperature of the second cells is at least one of reduced and minimized.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Further advantages features and details of the various embodiments of this disclosure will become apparent from 11 the ensuing description of a preferred exemplary embodiment and with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination recited, but also in other combinations on their own, with departing from the scope of the disclosure.

[0043] Advantageous embodiments of the invention are explained below with reference to the accompanying figures, wherein:

[0044] FIG. 1 depicts a first side view of an exemplary energy storage heat exchange system,

[0045] FIG. 2 depicts a second top view of the energy storage heat exchange system of FIG. 1, and

[0046] FIG. 3 depicts a process flow diagram for an exemplary process flow for a method of operating a heat exchanger for an energy storage heat exchanger system according to FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

[0047] As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B, or C” then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that “at least one of “A, B, and C” should be understood as including only one of A, only one of B, only one of C, or any combination.

[0048] For ease of understanding, in the following description the reference signs are used as follows Retain FIGS. 1 and 2 for reference.

[0049] FIG. 1 shows a schematic view of an energy storage heat exchange system 1 comprising an energy storage device comprising a plurality of electrochemical cells 2 for delivering and/or receiving electrical energy. The cells 2 are generally electrically connected in series.

[0050] Further cells 2 may be present perpendicular to the plane of the leaf or in the plane of the leaf and may be encompassed by the energy store. Preferably, cells are divided into modules with a certain number of cells 2, e.g. ten, which are distinguishable by the following characterized in that they are energized by the same heat-exchanging medium 6 in a flow direction S in order to conduct heat away from the cells 2. Due to the modular design, an energy storage device with almost any capacity can be constructed.

[0051] In the example, the heat-exchanging medium 6 is designed as a non-electrically conductive transformer 1, which is supplied by means of a pump 9 to the flow channel 5, in which the cells 2 are arranged and around which the heat-exchanging medium 6 flows. By means of the pump 9, the volume flow of the medium 6 in the flow channel 5, for example by increasing or decreasing the flow rate of the medium or by changing the pressure with which the medium 6 is acted upon. Advantageously, an incompressible medium 6 is used for this purpose, which simplifies the adjustment of the flow rate. After the heat-exchanging medium 6 has energized the cells 2 and energy has been transferred from the cells 2 to the heat-exchanging medium, this is fed to another heat exchanger. There it releases the absorbed heat back into the environment or another medium in order to avoid permanent heating of the heat-exchanging medium 6. Preferably, the heat-exchanging medium 6 is conducted in a circuit which serves exclusively to cool the cells 2 or the energy store. This heat exchange circuit is thus decoupled from other heat exchange circuits for, for example, the engine or the vehicle cabin.

[0052] In FIG. 1, each cell 2 has a different heat exchange surface 4. In this example, the respective cells 2 have good heat conductivity, for example metallic, outer wall. The cells 2 are positioned in housings 3, which structure, for example, a module that can accommodate a certain number of cells 2. The cells 2 are fixed in position in the current channel 5 by the housing 3, each of which accommodates one cell 2.

[0053] In the present case, the housings 3 are made of a material which has a poor thermal conductivity compared to the outer wall of the cells 2. For example, the housings are made of plastic. In this embodiment example, the housings 3 enclose the cells 2 in a jacket-like manner in such a way that substantially no heat-exchanging medium 6 can penetrate between the outer wall of the cell 2 and the housing 3. If the cross-section of cells 2 is round, the housing can have a cylindrical shell shape, wherein the inner radius of the cylindrical shell substantially corresponds to the outer radius of cell 2.

[0054] The different sizes of the heat exchange surface 4 for the cells 2 arranged one behind the other in the direction of flow S are now realized by the fact that the housings 3 have increasingly larger recesses in the direction of flow S, in which the heat is exchanged.

[0055] The outer wall of the cell 2 can come into contact with the heat-exchanging medium 6. These recesses from the housings can be distributed over the housing 3, in particular, uniformly over the surface of the outer wall of the cells 2. Alternatively, these can be formed in an interconnected manner, as shown in FIG. 1. i.e. the recess is formed as a contiguous cylinder jacket section, the recess being enlarged in the flow direction 2 for the cells 2 arranged one after the other. In this area, in which the heat-exchanging medium 6 covers the outer wall of the cells 2, the recess is formed as a coherent cylinder jacket section, a heat flow takes place from the warmer element, for example the cell 2, to the colder element, for example the medium 6. Usually, the cell 2 will have a higher temperature than the medium 6, so that a cooling of the cell 2 is caused, i.e. a warm flow from the cell 2 to the medium 6, in this case a cooling medium, takes place.

[0056] The area size of the heat exchange surface 4 is preferably determined in such a way that a temperature difference between the cells 2 is minimal at a given operating point and for given media flow parameters, in particular volume flow and media temperature at the inlet to the flow channel 5. Thus, it is an optimization problem under known boundary conditions. As a result, a corresponding heat exchange area distribution is obtained over the cells 2, which are flowed by the heat exchanging medium 6. Thus, the heat exchange area for each cell is determined in an optimized way. The housings 3 are adapted in the direction of flow S in such a way that the corresponding cell 2 each has a heat exchange area 4 that minimizes the temperature spread. The heat exchange areas 4 of the respective cells 2 then remain constant in size for the different operating points, but allow a minimum of a temperature difference or temperature spread of the cells 2 to be set by varying the volume flow.

[0057] Since the heat exchange surface 4 is determined by the housing 3, a cell 2 can also be replaced quickly without further ado. In this case, the minimization of the temperature spread is maintained without requiring any modification to the cell 2.

[0058] The first temperature sensor 7 is preferably positioned on the input side of the medium flow in the flow channel 5, preferably upstream of the first cell 2, which is irradiated by the medium 6. The second temperature sensor 8 is preferably arranged on the output side of the medium flow in the flow channel 5, in particular downstream of the last cell which is supplied with the medium 6. Temperature sensors 7 and 8 can include other functions, such as measuring the volume flow of the medium. Optionally, separate sensors, in particular in the flow channel, can also be provided for measuring the volume flow.

[0059] The cell currents of the cells 2, which are characteristic of the operating point of the energy store, can be fed to a control and/or regulating device 10. Likewise, the recorded measured values of the temperature sensors 7 and 8 and, if applicable, of the further sensors present can be fed to the control and/or regulating device 10.

[0060] The control and/or regulating device 10 has machine-readable program code 11, which allows a control intervention in the device for adjusting the volume flow 9, for example of a pump, of the heat-exchanging medium 6. The program code 11 is designed to adjust the volume flow of the medium 6 such that a temperature difference between the first cell in the flow direction and the last cell in the flow direction is reduced or minimal. This can be done via a controller or a controller. The program code 11 is stored in a non-volatile memory of the control and/or regulating device 10.

[0061] Furthermore, the program code 11 may be transferred to the control and/or regulating device 10 via a server or by means of a non-volatile storage medium.

[0062] Preferably, an actual volume flow of the medium 6 is detected via a sensor both for the control and for the control. In the case of the controller, this serves to verify the set volume flow present in the flow channel 5. In addition to the known conditions for the respective operating point of the cell, for example the cell current or a measure determined therefrom for the temperature of cell 2, to make a control intervention for the pump 9. The cell flow does not have to be measured; this can also be known from experience with regard to a certain power extraction of cell 2.

[0063] Depending on the current operating point of cells 2, an optimal volume flow rate for minimizing the temperature spread or the temperature difference is determined on the basis of a known characteristic curve field for the cell arrangement to be controlled. This is set by the control device 10 by means of the pump 9. The setting of the volume flow can be verified again via a volume flow sensor.

[0064] Since the operating point of the cells 2 can vary considerably within a short period of time depending on the power required or called up, the media temperature and the cell flow are preferably monitored continuously and the volume flow is adjusted accordingly, for example by regulating or controlling the process.

[0065] Furthermore, a determination of the temperature of at least the first and the last energized cell 2 in the direction of flow S can also be recorded or determined and, on the basis of the temperature difference, a regulation of the volume flow can be carried out by means of the control and/or regulating device 10 in such a way that the temperature difference between the cells 2 at the present operating point of the cells 2 becomes minimal.

[0066] FIG. 2 shows a 90° rotated view of the schematically illustrated energy storage heat exchanger system of FIG. 1. The reference signs of FIG. 2 have the same meaning as those of FIG. 1, as far as they are included in FIG. 2. From FIG. 2 in combination with FIG. 1 shows that the heat-exchanging medium 6 flows along the circumferential surfaces of the cells 2, but the front surfaces of the cells 2 are not surrounded by the heat-exchanging medium 6 in the control system and are thus available for sensors and energy supply and/or removal from the cells 2.

[0067] FIG. 3 shows a flow diagram for a method of operating an energy storage heat exchanger shown in FIG. 1 and FIG. 2. The diagram assumes that the energy storage heat exchanger is in operation and electrical energy is being drawn from the cells. This causes the cells to heat up. Cooling of the cells by means of a cooling medium, in that a heat-exchanging medium, in particular a cooling medium, flows around them as in FIGS. 1 and 2.

[0068] In a first method step S1 of measuring a temperature, a first temperature and a second temperature of the cooling medium are detected. The first temperature is measured upstream to the first cell, the second temperature is measured downstream to the last cell. These temperature values are fed to the control and/or regulating device.

[0069] In a second step S2 of the operating point determination process, the current operating point of the cells is checked and conditions characterizing the operating point are transmitted to the control and/or regulating device. If necessary, such a check of the operating point is carried out by the control and/or regulating device itself by communicating with a motor control or another control and requesting corresponding data, for example performance data.

[0070] In a third process step S3 of the check, the control and/or regulating device checks, on the basis of a characteristic curve field stored in the memory, whether the volume flow is suitable for the present parameters in the form of operating point and temperatures of the cooling medium. The characteristic diagram provides an optimum value for the volume flow for the corresponding parameters. If the flow rate for the cooling medium differs from the flow rate that leads to a minimum temperature difference between the first and last cell in the direction of flow, a control intervention takes place. In this case, the Y-path of the flow diagram is followed. If the set volume flow agrees with the value of the volume flow, at least within a predefined tolerance range, the characteristic curve field for the assigned parameters, no control intervention takes place. In this case, further continuous monitoring takes place until a control intervention is required. The N-path of the flow chart is followed.

[0071] In a fourth method step S4 of the control, the control and/or regulating device controls the device for adjusting the volume flow in such a way that the volume flow is increased or reduced to a volume flow predetermined, for example, from the characteristic curve field. This subsequently leads to the fact that the temperature difference of the first and last cell in the direction of current flow is reduced, thereby reducing or minimizing the temperature spread in its entirety between this first and last cell.

[0072] In an optional fifth step S5 of the test, the control and/or monitoring system checks control device whether the determined value of the volume flow from the characteristic curve field corresponds to the value currently present in the flow channel after the control intervention. If this is the case, the operating point and the temperatures of the medium are monitored again until the next control action. Otherwise, a further control intervention takes place until the desired value of the volumetric flow, which is obtained by changing the temperatures and/or the operating point is achieved in the cooling flow channel. In this case, the adjustment of the volume flow on the basis of a changed setpoint value of the volume flow due to changed media temperatures and/or change of the operating point enjoys priority over the tracking of an actual volume flow to an “outdated” value for the setpoint volume flow.

[0073] Since the devices and methods described in detail above are examples of embodiments, they may be modified to a wide extent by a person skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the proportions of the individual elements of the invention are described in detail and are to each other merely exemplary.