DE102017212309B3 - Coolant circuit with at least two cooling circuits and a latent heat storage - Google Patents

Abstract

The invention relates to a coolant circuit (100, 200) for cooling at least two heat sources (1, 2, 3), in particular in a motor vehicle, comprising a coolant with a cooling fluid and a predetermined volume fraction of a latent heat accumulator (4, 5, 6, 7), a first cooling circuit (11) for cooling a first, warmer heat source (1), a second cooling circuit (13, 25) for cooling a second, cooler heat source (2), and a heat exchanger (18) with a heat exchanger section (19) a part of both cooling circuits (11, 13, 25), and a method for adjusting the coolant circuit.

Description

The invention relates to a coolant circuit for cooling at least two heat sources, in particular in a motor vehicle, and to a method for adapting a coolant circuit.

In motor vehicles, coolant circuits are often used for cooling different heat sources, in particular for cooling drive components, energy stores or electrical consumers. In motor vehicles with internal combustion engines, this often means that with the internal combustion engine on the one hand and with electrical components (for example a traction battery, a SuperCap, a fuel cell, but also the electric machine of a hybrid vehicle) on the other hand heat sources with very different operating temperatures must be cooled.

In internal combustion engines - in particular because of the combustion processes - by means of the coolant often heat must be removed from surfaces having a surface temperature of several 100 ° C. For electrical machines, this temperature is usually not much higher than 80 ° C, because the typically used magnets could be damaged at higher temperatures. At a similar temperature level, for example, SuperCaps or fuel cells are operated with a Proton Exchange Membrane (PEM), which accordingly must also be cooled to such a temperature level. In the traction battery of hybrid vehicles often a maximum temperature in the range of 25 to 40 ° C must be maintained, with alkaline cell chemistries rather in a temperature range between 30 and 40 ° C, Li-ion-based cell chemistries rather in a temperature range below 30 ° C operated become.

Therefore, for example, in common hybrid vehicles, two or three separate coolant circuits are provided, which are adapted to the temperature level of one or the other heat source in terms of their geometric design, the volume of coolant used and / or the selection of the coolant used.

Are known, for example from the DE 10 2009 023 724 A1 , including motor vehicles, in which heat sources with different temperature levels are cooled with a coolant circuit with a common heat exchanger for heat dissipation. Integrated coolant circuits have the advantage that they require less space and less assembly, in particular because of the common heat exchanger section and thus have less weight and lower costs.

However, these coolant circuits have the disadvantage that there is a higher temperature difference to the coolant in the warmer, to be cooled heat source than in (the) cooler, to be cooled heat source (s). Because of the associated, better heat transfer between the warmer temperature source and the coolant, this can be better cooled than the cooler heat source (s).

A sufficiently low coolant temperature in order to optimally cool the cooler heat source due to a sufficient temperature difference can also be achieved only with great difficulty, in particular with an advantageously simple air cooling system.

From the DE 10 2012211140 A1 For example, a closed fluid medium flow path circuit is known in which a liquid coolant with micro phase change material can be circulated through a plurality of cooling fins to cool a vehicle battery. The coolant may pass from an inlet through a cooling flow path to an outlet, wherein the flow path may take the form of many, substantially parallel, individual paths or channels. If necessary, a heat exchanger is arranged between the outlet and the inlet.

From the documents DE 103 18 044 A1 . DE 196 54 035 A1 . DE 10 2005 061 195 A1 . DE 10 2010 009 181 A1 . DE 10 2010 040 829 A1 . JP 2003/129844 A and US 2004/0019123 A1 In each case further designs of a coolant circuit with a cooling circuit are known, the coolant has a phase change material.

Against this background, it is an object of the invention to provide an improved coolant circuit for cooling at least two heat sources.

This object is achieved by a coolant circuit with the features of claim 1 and by a method having the features of claim 11. Advantageous embodiments are the subject of the dependent claims.

According to one aspect of the invention, a coolant circuit for cooling at least two heat sources, in particular in a motor vehicle, is provided. The coolant circuit comprises: (a) a coolant having a cooling fluid and a predetermined volume fraction of a latent heat accumulator, (b) a first cooling circuit for cooling a first, warmer heat source, in particular a higher operating temperature of a surface to be cooled, (c) at least one second cooling circuit for cooling a second, cooler heat source, in particular a lower operating temperature of a surface to be cooled, and (d) a heat exchanger with a heat exchanger section, preferably a part of both Cooling circuits, ie in particular the first and the second and possibly each other cooling circuit, is.

The second cooling circuit has a subcooling section which is configured to further cool the coolant, in particular to a temperature below a phase change temperature of the latent heat accumulator, in particular after cooling (= removal of heat from the coolant, for example by means of air cooling) in the heat exchanger. According to one embodiment, the coolant in the subcooling section is cooled sufficiently lower than the phase change temperature and / or sufficiently long out in the subcooling, so that the phase change of the latent heat accumulator, in particular as completely as possible, can take place.

According to a further aspect of the invention, a method for adapting a coolant circuit, in particular according to an embodiment of the aspect described above, is provided. The method comprises the steps of: (i) determining an operating temperature of the second heat source, (ii) determining a desired phase change temperature of the phase change material as a function of the operating temperature of the second heat source, and (iii) mixing the coolant from a cooling fluid and a latent heat storage with the determined phase change temperature.

The invention is based inter alia on the finding that a coolant circuit with respect to its geometrical and / or coolant-related design normally only to a (single) certain temperature difference between an operating temperature of the coolant to be cooled surface of the heat source on the one hand and an operating temperature of Cooling surface itself can be optimized on the other hand and that also in the most desired air cooling due to the air temperature predetermined by the ambient air only a lesser temperature gradient can be achieved, the closer the temperature of the surface to be cooled is at the temperature of the ambient air. In particular, cooling of two heat sources with different operating temperatures of the respective surface to be cooled can take place at most for one of these surfaces in the optimized region; usually for the higher temperature surface, because there the heat transfer - especially on a fluid-based coolant - is more pronounced due to the higher temperature difference.

The invention is based inter alia on the idea of providing in a coolant circuit both a conventional cooling fluid, such as water with an antifreeze, and a portion of a latent heat storage, such as a suitable paraffin.

In particular, a first cooling circuit is now designed such that a warmer heat source can be cooled optimally with the cooling fluid, and a second cooling circuit is designed such that a cooler heat source can be cooled optimally with the latent heat storage.

Although it is - especially in a pure air cooling - difficult even with a subcooling for the second cooling circuit, the cooling fluid to convey a sufficiently low temperature for an optimized heat transfer to the second heat source. However, the high heat capacity of the latent heat storage during the phase change, can be used to still dissipate a relatively large amount of heat.

In addition, according to an embodiment, in particular by the installation of a flow restrictor, such as a throttle, the residence time of the cooling medium in the cooler operated cooling circuits, and in particular in the associated subcooling, can be increased, whereby a greater cooling of the cooling medium can be achieved in these cooling circuits. This stronger cooling can then work in conjunction with the higher heat capacity thanks to phase change of the phase change material.

For this purpose, according to an embodiment in the second cooling circuit, in particular between the subcooling section, and the second heat source, a volumetric flow limitation is arranged, which in particular has a throttle.

In order to ensure a reliable phase change to the solid state of the latent heat storage, according to one embodiment, the subcooling between the heat exchanger section and the second heat source is arranged.

To ensure a compact and simple design of the coolant circuit according to one embodiment, the subcooling is arranged on the heat exchanger. In this case, a branch point between the first and the second cooling circuit is arranged in particular between the heat exchanger section and the subcooling.

In order to avoid settling of the latent heat accumulator in the coolant circuit and / or to ensure a uniform distribution of the latent heat accumulator in the coolant circuit has, according In one embodiment of the latent heat storage device, a plurality of microcapsules in which a phase change material (also referred to as "phase change material" (PCM) or microencapsulated phase change materials slurries (mPCMS)), for example a suitable paraffin or a salt, is fluid-tightly encapsulated.

In order to enable reliable operation in conjunction with a water-based cooling fluid, as provided in one embodiment, the microcapsules according to one embodiment comprise an at least substantially inert polymeric material having a thermal stability of at least 150 ℃, especially at least 250 ℃, especially a wall thickness of less than 2% to less than 25% of the diameter of the microcapsule, on. The wall of the microcapsules may each have, for example, a diameter of between 0.5 μm and 30 μm.

In order to be able to adapt the coolant circuit to different conditions of use (such as surface temperature of the cooler heat source to be cooled, size and / or shape of the surface to be cooled of the cooler heat source, etc.), according to one embodiment, the predetermined volume fraction of the latent heat accumulator is the volume of the entire Coolant between 10% and 25%, preferably between 15% and 20%.

An adaptation to the conditions of use can also be done by a suitable selection of the phase change material. According to one embodiment, the phase change material may contain a paraffin, a fatty acid ester, a salt, and / or a suitable other PCM, the suitability of which may result inter alia from the phase change temperature.

For example, depending on the required phase change temperature, paraffins having a different number of carbon atoms can be used, especially with 14 to 34 carbon atoms in a paraffinic hydrocarbon. Thus, phase change temperatures between 5.5 ° C (e.g., 14 carbon paraffin) and 76 ° C (e.g., 34 carbon paraffin) can be achieved. For example, in the present case for cooling a hybrid automotive traction battery, a paraffin with 20 C atoms can be used, which has a phase change temperature of almost 37 degrees Celsius, while an electric motor can be cooled, for example, with a paraffin with 27 C atoms, which is scarce 59 ° C the phase changes. For fine adjustment of a specific phase change temperature, microcapsules with different paraffins can be used according to an embodiment, wherein the mixing ratio is then to be selected in particular as a function of the phase change temperature to be set.

If a water-based cooling fluid is used, it may be provided according to an embodiment to add an application-specific required amount of a suitable antifreeze such as glycol to the water. Typically, a cooling fluid may comprise approximately equal amounts of water and glycol, for example, substantially one-half of water or glycol, respectively.

Furthermore, the cooling fluid preferably serves to receive and transport the latent heat accumulator, in particular the microcapsules, in the coolant circuit.

In order to provide optimized cooling performance with respect to the cooler heat source (s), according to one embodiment, the phase change material has a phase change temperature which is tuned to an operating temperature of the second and / or further heat source.

In order to be able to cool more than two heat sources with different operating temperatures, according to one embodiment, the coolant circuit to a third cooling circuit for cooling a third, even cooler heat source, wherein the heat exchanger section, and preferably the subcooling of the second cooling circuit is part of the third cooling circuit , and wherein the latent heat storage device has a second phase change material with a second phase change temperature, which is tuned in particular to an operating temperature of the third heat source.

In this case, according to one embodiment, the third cooling circuit has a further subcooling path, which is in particular configured to cool the coolant to a temperature below the second phase change temperature.

In order to be able to cool more than three heat sources with different operating temperatures, according to one embodiment the coolant circuit has at least one further cooling circuit with a further subcooling path, in particular for cooling a further heat source with a different operating temperature.

In particular, in an application of an embodiment of the invention in a motor vehicle, for example, be provided that the first heat source is an internal combustion engine and the second heat source is an electric machine. But it can also be provided that the first heat source is an internal combustion engine and the second heat source is an electrical consumer or a Energy storage device, for example, for an electric drive, or that the first heat source is an electric machine and the second heat source is an electrical consumer. Preferably, the first heat source is an internal combustion engine and the second heat source is an electric machine and the third heat source is an energy storage device such as a vehicle battery, for example a hybrid or an electric vehicle.

In order to ensure reliable operation of the coolant circuit, according to one embodiment, this has a coolant pump, which is arranged in particular between a confluence of the two cooling circuits and the heat exchanger section.

According to one embodiment, an operating temperature of the first heat source is determined, a temperature difference between the operating temperatures of the two heat sources is determined, and a length and / or heat dissipation of the subcooling path is determined as a function of this temperature difference. Thus, the subcooling can be adapted to the application.

From this temperature difference, according to an embodiment, the predetermined proportion of the latent heat storage can be determined in the volume of the entire coolant in order to achieve an optimized cooling effect, in particular at the cooler heat source.

According to one embodiment, depending on the operating temperature of a third heat source, a further desired phase change temperature for a further phase change material of the latent heat accumulator can be determined and the coolant can be mixed with two different phase change materials.

In particular, the method steps described in this application for two cooling circuits can also be carried out analogously for a coolant circuit with further cooling circuits and a corresponding number of different phase change materials.

• 1 einen Kühlmittelkreislauf gemäß einer beispielhaften Ausführung der Erfindung mit zwei Kühlkreisen in einer schematischen Ansicht; und
• 2 einen Kühlmittelkreislauf gemäß einer weiteren beispielhaften Ausführung der Erfindung mit drei Kühlkreisen in einer schematischen Ansicht.

Other features, advantages and applications of the invention will become apparent from the following description taken in conjunction with the figures. Show it:

• 1 a coolant circuit according to an exemplary embodiment of the invention with two cooling circuits in a schematic view; and
• 2 a coolant circuit according to another exemplary embodiment of the invention with three cooling circuits in a schematic view.

In 1 is a coolant circuit 100 for cooling a first heat source 1 and a second heat source 2 shown. The first heat source 1 is in the embodiment, an internal combustion engine of a motor vehicle with hybrid drive and has a temperature of several hundred degrees Celsius on a surface to be cooled. The second heat source 2 is in the embodiment, an electric motor of the motor vehicle and has an operating temperature of about 80 ° C on a surface to be cooled. At similar temperature levels could be cooled in other embodiments with an exemplary cooling circuit with the features described below (if necessary, necessary geometric adjustments in the connection of the heat source) and a SuperCap arrangement or a PEM fuel cell.

The coolant circuit 100 has a first cooling circuit 11 for cooling the internal combustion engine 1 on. The coolant lines of the first cooling circuit 11 are marked with solid arrows. At the surface of the internal combustion engine to be cooled 1 indicates the first cooling circuit 11 preferably a load path 12 along, along which the heat of the internal combustion engine is transferred to the coolant, in particular to the cooling fluid. It is thus provided that the cooling fluid (in the exemplary embodiment in approximately equal amounts of water and glycol) remains in the liquid state, in particular does not exceed a temperature of 130 ° C.

Furthermore, the coolant circuit 100 a second cooling circuit 13 for cooling the electric motor 2 on. The coolant lines of the second cooling circuit 13 are drawn with long-drawn arrows. At the surface of the electric motor to be cooled 2 indicates the second cooling circuit 13 preferably a load path 14 along, along which the heat of the electric motor is transmitted to the coolant. The heat transfer in the second cooling circuit 13 takes place at a lower temperature than in the first cooling circuit 11 in the internal combustion engine. The heat transfer from the surface of the electric motor to be cooled 2 on the cooling fluid is therefore limited.

Both cooling circuits 11 and 13 unite in front of a coolant pump 16 which the coolant (ie the cooling fluid and the microcapsules received therein) through the coolant circuit 100 inflated.

From the pump 16 up to a heat exchanger 18 are the two cooling circuits 11 and 13 in a pumping section 17 trained together. In the heat exchanger 18 is a heat exchanger section 19 formed at the downstream end of a branching point 20 is provided, at which the first cooling circuit 11 and the second cooling circuit 13 separate.

During the first cooling cycle 11 from the branching point 20 from directly to the internal combustion engine to be cooled 1 is passed, passes through the second cooling circuit 13 first a subcooling line 22 in which the coolant is still above the cooling level of the heat exchanger 18 is further cooled, namely to a temperature below the phase change temperature of the example provided phase change material (paraffin with 27 carbon atoms) of almost 59 ° C. The length of the subcooled section 22 is preferably carried out so that due to a temperature of well below 59 ° C and / or due to a prolonged exposure of the microcapsules in a temperature below 59 ° C, the paraffin in the subcooling 22 goes into the solid state. After passing through the subcooling section 22, the coolant is the electric motor to be cooled 2 fed.

The coolant circuit comprises a coolant with a mixture of water and glycol as the cooling fluid (not shown), in which a predetermined volume fraction of a latent heat storage flows, symbolically with the reference numerals 4 and 5 referred to as. The reference numerals 4 and 5 are directed to a paraffin with 27 C atoms as a phase change material whose phase change temperature is set in a conventional manner by the composition of the paraffin to just 59 ° C. The latent heat storage is in the coolant circuit in the form of microcapsules.

The reference number 4 denotes an exemplary microcapsule in which the phase change material is in the liquid state (T> 59 ° C). For a better illustration, the microcapsules in the FIGURE are marked with a multiplicity of small dots as filling at locations in the coolant circulation at which the paraffin predominantly is liquid.

The reference number 5 denotes an exemplary microcapsule in which the phase change material is in a solid state (T <59 °). For better illustration, the microcapsules in the figure with a diamond pattern as filling are drawn in places in the coolant circulation, in which the paraffin is predominantly solid.

Of the 1 can therefore be seen that in the subcooling 22 the microcapsules in a solid state 5 transferred and then the to be cooled electric motor 2 be guided. Thus, if necessary, it is ensured that the coolant sufficiently long in the subcooling 22 remains, a volumetric flow limitation, in particular be provided downstream of the subcooling. This is in the embodiment of 1 as a controllable throttle 21 executed. In particular, if no volumetric flow limitation is required, the throttle can be completely opened.

At the electric motor 2 becomes the phase change material along the load path 14 converted into a temperature range above its phase change temperature, which is why the refrigerant absorb heat energy of the electric motor 2 due to the microcapsules and for the melting (the phase change from solid to liquid) of the paraffin can use. After passing the running track 14 the microcapsules are again in the liquid state 5 before, and can over the pump 16 turn the heat exchanger 18 and later the subcooling line 22 be supplied.

In 2 is a coolant circuit 200 shown, for cooling three different tempered heat sources 1 . 2 and 3 is provided. In the embodiment, the heat source 1 the internal combustion engine of a hybrid vehicle, the heat source 2 an electric motor of the vehicle and the heat source 3 an energy storage package (exemplified here a traction battery with alkaline cell chemistry) of the vehicle.

Typical cooling conditions of an internal combustion engine and an electric motor are too 1 described. The traction battery 3 Due to the cell chemistry, however, the vehicle may only reach temperatures of 30 ° C to 40 ° C, depending on the design.

Order now with a single coolant circuit 200 To provide for optimized cooling at three different temperature levels, the coolant circuit is different 200 from the according to 1 in particular in that a third cooling circuit 25 with a load route 26 for cooling the traction battery 3 is provided. The coolant lines of the third cooling circuit 25 are drawn with short-dashed arrows.

The third cooling circuit 25 has its own subcooling line 28 which is traversed by coolant, which after passing through the first subcooling 22 of the second cooling circuit 13 is branched off. Also in this embodiment is downstream of the subcooling 22 a throttle 21 arranged for flow limitation. Likewise, the third cooling circuit has a flow limitation in the form of a throttle 27 on which downstream of the subcooled section 28 is arranged.

The coolant of the coolant circuit 200 has as latent heat storage on a mixture of microcapsules with two different paraffins. Thus, a plurality of microcapsules containing a 27-C paraffin in the coolant, the phase change temperature of the electric motor 2 for cooling in the second cooling circuit 13 is matched, and a variety of microcapsules with a 20-C paraffin (phase change at just 37 ° C), its phase change temperature on the traction battery 3 for cooling in the third cooling circuit 25 is tuned. For this purpose, depending on the design of the traction battery (in particular with regard to the required maximum operating temperature of the traction battery used), for example, a phase change temperature of 30, 35 or 40 ° C in question, with appropriately adapted paraffin mixture. With such a third cooling circuit, for example, in another embodiment, a traction battery with an alkaline cell chemistry can be cooled.

In another exemplary embodiment, the third cooling circuit may also cool a traction battery of the vehicle based on lithium cells. Because these types of batteries often have a lower maximum operating temperature in the range below 30 ° C, but then, if necessary - especially for use in so-called hot countries - also an additional heat pump must be installed to provide the required cooling effect can.

Symbolic are in 2 the microcapsules 1 although smaller but with the same symbols and the reference numbers 4 and 5 shown. The microcapsules for cooling the traction battery 3 are designed for distinctness with thinner edge lines. The liquid state is denoted by the reference numeral 6 , the solid state by the reference numeral 7 designated.

When the coolant is the heat exchanger section 19 leaves, both types of microcapsules in the liquid state (reference numerals 4 and 6 ). Here, part of the coolant becomes the first cooling circuit 11 fed. The other part will be in the first subcooled section 22 where the microcapsules with a phase change temperature of 59 ° C the solid state (reference numeral 5 ) accept. Downstream of the first subcooling section 22 Part of the coolant is supplied to the second cooling circuit 13. The remaining part is in the further subcooling 28 introduced where the microcapsules with the lower phase change temperature of 37 ° C assume the solid state (reference numeral 7 ). These microcapsules then cool the traction battery 3 by absorbing its heat energy during phase change.

For determining the composition of the coolant in a coolant circuit 100 according to 1 or 200 according to 2 the operating temperatures of the cooler heat source (s) 2 (and 3) to be cooled are determined and from this the desired phase change temperature of the phase change material (s) is determined. The volume fraction of the microcapsules on the coolant can be up to 20% in the normal case, without affecting the viscosity of the coolant relevant, and can be determined, for example, as a function of temperature differences between the heat sources to be cooled and / or from an amount of heat to be dissipated at a heat source.

LIST OF REFERENCE NUMBERS

1

first heat source (internal combustion engine)

2

second heat source (electric motor)

3

third heat source (traction battery)

4

Microcapsule (higher phase change temperature / liquid)

5

Microcapsule (higher phase change temperature / solid)

6

Microcapsule (lower phase change temperature / liquid)

7

Microcapsule (lower phase change temperature / solid)

11

first cooling circuit

12

first load route

13

second cooling circuit

14

second load path

16

Coolant pump

17

pump track

18

heat exchangers

19

heat exchange path

20

branching point

21

Throttle in the second cooling circuit

22

Under cooling section

25

third cooling circuit

26

third load route

27

Throttle in the third cooling circuit

28

further subcooling section

100

Coolant circuit

200

another coolant circuit

Claims (14)

Coolant circuit (100, 200) arranged for cooling at least two heat sources (1, 2, 3), comprising - a coolant with a cooling fluid and a predetermined volume fraction of a latent heat accumulator (4, 5, 6, 7), - a first cooling circuit (11) adapted to cool a first, warmer heat source (1); - at least one second cooling circuit (13, 25) adapted to cool a second, cooler heat source (2, 3); second cooling circuit (13, 25) has a subcooling section (22, 28) which is configured to cool the coolant to a temperature below a phase change temperature of the latent heat accumulator (5, 7), and - a heat exchanger (18) having a heat exchanger section (19) which is part of both cooling circuits (11, 13, 25). Coolant circuit (100, 200) according to Claim 1 wherein the subcooling section (22) is arranged between the heat exchanger section (19) and the second heat source (2, 3). Coolant circuit (100, 200) according to one of the preceding claims, wherein in the second cooling circuit (13, 25), a flow restriction (21, 27) is arranged. Coolant circuit (100, 200) according to one of the preceding claims, wherein the subcooling section (22, 28) is arranged on the heat exchanger (18). Coolant circuit (100, 200) according to one of the preceding claims, wherein the latent heat storage comprises a plurality of microcapsules (4, 5, 6, 7), in which a phase change material is fluid-tightly encapsulated. Coolant circuit (100, 200) according to one of the preceding claims, wherein the predetermined volume fraction of the latent heat accumulator in the volume of the total coolant is between 10% and 25%. Coolant circuit (100, 200) according to one of the preceding claims, wherein the phase change material has a phase change temperature, which is tuned to an operating temperature of the second heat source (2). Coolant circuit (100, 200) according to one of the preceding claims, comprising a third cooling circuit (25) which is designed to cool a third, even cooler heat source (3), wherein the heat exchanger section (19) is a part of the third cooling circuit (25), and wherein the latent heat accumulator has a second phase change material (6, 7) with a second phase change temperature, which is tuned to an operating temperature of the third heat source (3). Coolant circuit (100, 200) according to Claim 8 wherein the third cooling circuit (25) includes a subcooling section (28) configured to cool the coolant to a temperature below the second phase change temperature. Coolant circuit (100, 200) according to Claim 8 or 9 , comprising at least one further cooling circuit with a further subcooling section, which is set up for cooling a further heat source with a different operating temperature. Method for adapting a coolant circuit (100, 200) according to one of the preceding claims, comprising the steps: Determining an operating temperature of the second heat source (2), Determining a desired phase change temperature of the phase change material (4, 5) as a function of the operating temperature of the second heat source (2), - Mixing of the coolant from a cooling fluid and a latent heat storage (4, 5) with the determined phase change temperature. Method according to Claim 11 additionally comprising the steps of: determining an operating temperature of the first heat source, determining a temperature difference between the operating temperatures of the two heat sources, determining a length of the subcooling path as a function of the temperature difference. Method according to Claim 12 additionally comprising the steps of: determining the predetermined volume fraction of the latent heat accumulator (4, 5, 6, 7) in the volume of the total coolant as a function of the temperature difference. Method according to one of Claims 11 to 13 for adapting a coolant circuit (100, 200) according to one of Claims 8 to 10 , wherein depending on the operating temperature of the third heat source (3) determines a further desired phase change temperature for another phase change material (6, 7) of the latent heat accumulator (4, 5, 6, 7) and the coolant is mixed with two different phase change materials.

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