Material thermal flow management in cooled lines

Abstract

The present invention relates, inter alia, to a cable comprising: a) at least one core, wherein each core has a conductor and core insulation surrounding the conductor, b) at least one coolant channel, wherein the cable comprises an electrically insulating heat transfer layer, wherein this heat transfer layer comprises: i) at least one polymer, and ii) one or more inorganic fillers in a proportion of 35 to 65 wt.%, based on the weight of the heat transfer layer, wherein the one or more inorganic fillers have a hydrophobic surface modification, wherein the heat transfer layer is used (i) as the sheathing material of the at least one coolant channel, (ii) as core insulation of the at least one core, and / or (iii) as a solid cable filler material enclosing the at least one core and the at least one coolant channel.

Description

[0001] The present invention relates to a cooled cable with a heat transfer layer that enables material-based heat flow management in the cable. State of the art

[0002] Depending on the cable geometry, at certain high currents, such as those found in charging cables and high-voltage cables of electric vehicles, the resulting heat loss can no longer be passively dissipated via the insulation and sheath. Reducing heat loss by increasing the conductor cross-section is also impractical due to handling difficulties and space limitations. Therefore, these cables are actively cooled using one or more hoses through which a cooling medium flows. Until now, the focus for optimizing cooling performance has primarily been on the general cable design and, in particular, the geometric design of the hoses.

[0003] The unmodified polymers commonly used as hose materials are generally poor thermal conductors, with thermal conductivity in the range of 0.2 W / mK. This creates a barrier in the overall heat flow of the pipe, significantly hindering the targeted coupling of heat energy into the cooling medium and allowing heat to dissipate into other pipe components.

[0004] Particularly in high-voltage cables, poor heat dissipation leads to a reduction in the potential current-carrying capacity of the cable, as defined limits for, e.g., surface or conductor temperature are reached and exceeded sooner. By selectively increasing the thermal conductivity of the hose material, the heat flow could be better directed and the dissipation of heat into the cooling medium significantly improved.This is not readily possible for electrical conductors according to the current state of the art, since classic fillers that increase the thermal conductivity of polymeric materials either have a metallic character and therefore massively impair electrical properties, primarily the volume resistance and dielectric strength, which are essential for the safe operation of the conductor, or are of mineral origin and therefore, in the necessary high concentration, impair the mechanical properties of the material used, for example the flexibility, to such an extent that its practical use in a conductor is no longer possible.

[0005] The increase in thermal conductivity in a cable through the use of metallic components is described in EP 2 652 754 B1 and DE 10 2017 105 985 A1.

[0006] CN 114342009 A describes an actively cooled charging cable in which the dissipation of heat loss is improved by introducing a liquid silicone polymer between the conductive metal of the cable and the coolant tube. Furthermore, thermally conductive pastes with inorganic additives are described in JP 2010 278 115 A and JP 2 930 298 B1.

[0007] Patent specification CN 106366621 A proposes an improvement in heat dissipation through the use of a mixture of a thermoplastic polyurethane elastomer, polyvinyl chloride and other compounds, including a small proportion of aluminum oxide and aluminum nitride, in a cable.

[0008] Another thermally conductive material for use in a cable is disclosed in CN 110452443 A. Boron nitride is embedded in a matrix of cross-linked polyethylene with a weight fraction of 14.5 - 35.9 wt.%.

[0009] The use of an inorganic filler treated with organosilanes, in combination with an ethylene-based polymer, for use as an insulating material for electrical conductors was described in US 3802913. The increase in thermal conductivity was not considered in this case.

[0010] A key element of the present invention is the incorporation of a mineral filler with a matrix-active surface modification, which on the one hand increases the thermal conductivity to a sufficient level, while on the other hand, through the physical binding of the filler into the polymer matrix, sufficiently maintains the mechanical properties. The fundamental electrical properties of the material remain unaffected due to the mineral nature of the filler. This combination of properties enables the present invention to implement a thermal management concept through the targeted control of heat flow in flexible, current-carrying applications.

[0011] The present invention therefore enables a significant increase in the current-carrying capacity of the conductor while maintaining the conductor geometry. Summary of the invention

[0012] The invention relates to a cable with a heat transfer layer that ensures effective heat transfer from the current-carrying conductors of the cable to the coolant guide, and thus enables a high current-carrying capacity while adhering to specified maximum surface temperatures of the cable.

[0013] In particular, the invention relates to a cable comprising: a) at least one conductor, each conductor comprising a conductor and conductor insulation surrounding the conductor, b) at least one coolant guide, wherein the cable includes an electrically insulating heat transfer layer, wherein this heat transfer layer comprises: i) at least one polymer, and ii) one or more inorganic fillers in a proportion of 35 to 65 wt.%, based on the weight of the heat transfer layer, wherein one or more inorganic fillers have a hydrophobic surface modification, wherein the heat transfer layer (i) is used as sheath material of the at least one coolant guide, (ii) as conductor insulation of the at least one conductor and / or (iii) as solid cable filler material enclosing the at least one conductor and the at least one coolant guide.

[0014] Furthermore, the invention also relates to a hose comprising a polymer comprising or consisting of polyurethane, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, styrene-isoprene rubber, polyethylene terephthalate, polyamide, polystyrene, polyester, polyether, polycarbonate, or a mixture thereof, and one or more inorganic fillers in a proportion of 35 to 65 wt.%, based on the weight of the hose, comprising or consisting of at least one selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbonates, metal sulfates, metal phosphates and mixtures thereof, preferably metal hydroxides, metal oxides and mixtures thereof, and preferably comprising aluminum oxide, wherein the one or more inorganic fillers have a hydrophobic surface modification, wherein the surface modification comprises a silane with at least one silicon-carbon bond, and preferably comprises vinylsilane.wherein the hose i) has a specific thermal conductivity of more than 0.2 Wm⁻¹ < K⁻¹ < , ii) has a specific volume resistivity of at least 10 GΩ·mm at 20 °C, measured according to ISO 19642, iii) has a tensile strength, measured according to DIN EN 60811-501, of at least 10 MPa, and iv) has sufficient cold flexibility so that the hose passes a cold coiling test according to ISO 19642 at -40 °C.

[0015] Furthermore, the invention relates to a cable containing a hose according to the invention.

[0016] The invention further relates to a method for heat flow management of a cable, comprising a) the provision of a cable according to the invention, b) the transmission of electrical energy through the cable, c) the active transport of a suitable coolant, preferably a cooling liquid, through which at least one coolant guide is located during the operation of the cable, where the surface temperature of the charging cable is measured at a power current of 525 A, using a cable with a nominal conductor cross-section of at least 25 mm² 2 , does not exceed a temperature of 70 °C. Detailed description of the invention

[0017] The present invention, as defined in the claims, describes a cable with at least one core and at least one coolant channel. The at least one core comprises a conductor and core insulation surrounding the conductor. The cable includes an electrically insulating heat transfer layer with at least one polymer and one or more inorganic fillers, wherein the one or more fillers have a hydrophobic surface modification. The heat transfer layer is used as the sheathing material of the at least one coolant channel, as core insulation of the at least one core, and / or as a solid cable filler material enclosing the at least one core and the at least one coolant channel. The coolant channel is designed such that a coolant can be contained and / or transported within it. The terms coolant and cooling medium are used synonymously.

[0018] The heat transfer layer is electrically insulating and comprises one or more polymers and one or more inorganic fillers. In the cable according to the invention, the heat transfer layer is used as the sheathing material of the at least one coolant conductor, as conductor insulation of the at least one conductor, and / or as a solid cable filler material.

[0019] The conductors contained within a cable can be current-carrying conductors, used for transmitting energy and / or power. In addition to these current-carrying conductors, the cable can also contain other conductors that serve as signal lines, carrying information signals. Information signals are electrical impulses that transmit information, not energy. A conductor comprises an electrical conductor, such as a metal, and insulation made of an electrically insulating plastic. A conductor may also include a coolant channel. The transmission of energy in the form of electric current in a current-carrying conductor leads to heating of the conductor and thus to heating of the conductor itself. The generated heat is dissipated via the coolant in the coolant channel. For this purpose, the heat dissipates through the components of the cable.The heat transfer layer improves heat transfer between components of the cable.

[0020] The heat transfer layer comprises at least one polymer and at least one inorganic filler with a weight fraction of 35–65 wt.%, preferably 40–60 wt.%, and particularly preferably 40–50 wt.%. The heat transfer layer can also include the at least one polymer with a weight fraction of 35–65 wt.%, preferably 40–60 wt.%, and particularly preferably 50–60 wt.%.

[0021] The heat transfer layer is characterized by a higher thermal conductivity than the corresponding polymer without inorganic filler. The thermal conductivity, measured according to DIN EN ISO 22007-1:2018-03 (method using a heat flux plate device; preferably measured with a TA Instruments FOX 50 test device), can be greater than 0.2 W / m²K, preferably greater than 0.3 W / m²K, and most preferably greater than 0.35 W / m²K.

[0022] The heat transfer layer is electrically insulating. It can have a specific volume resistance of at least 10 GΩ·mm, preferably at least 12 GΩ·mm, and particularly preferably at least 15 GΩ·mm at 20 °C, measured according to ISO 19642.

[0023] The addition of inorganic filler is expected to impair the mechanical properties of the polymer used, such as its tensile strength. The tensile strength of the heat transfer layer, measured according to DIN EN 60811-501: 2019; test on a standard-sized rod; thickness 1 mm; tensile speed 25 mm / min for PE-X; 250 mm / min for all other materials, can be at least 10 MPa, preferably at least 12 MPa, and particularly preferably at least 15 MPa. If the heat transfer layer is used as a coolant guide for the cable, the tensile strength of the coolant guide, measured using a method as described above, can be at least 10 MPa, preferably at least 12 MPa, and particularly preferably at least 15 MPa.

[0024] The heat transfer layer is used in the cable as conductor insulation of the at least one conductor, as sheathing material of the at least one coolant channel and / or as cable filling material that surrounds the at least one conductor and the at least one coolant channel.

[0025] The cable of the present invention can comprise a cable filling material. The cable filling material is a solid material and surrounds the at least one conductor and the at least one coolant channel of the cable and can consist of the heat transfer layer.

[0026] Possible embodiments include the use of the heat transfer layer as conductor insulation of the at least one conductor, or as sheath material of the at least one coolant channel, or as cable filling material, or as conductor insulation of the at least one conductor and as sheath material of the at least one coolant channel, or as conductor insulation of the at least one conductor and as cable filling material, or as sheath material of the at least one coolant channel and as cable filling material, or as conductor insulation of the at least one conductor and as sheath material of the at least one coolant channel and as cable filling material.

[0027] The heat transfer layer can be in direct contact with the conductor of at least one wire. Additionally or independently, the heat transfer layer can be in direct contact with the coolant contained within the coolant guide, particularly if the sheathing material of the coolant guide encompasses the heat transfer layer.

[0028] Direct contact between the heat transfer layer and the conductor and / or the coolant enables improved heat transfer from the conductor, which acts as a heat source during cable operation and from which heat needs to be dissipated, to the coolant, which acts as a heat sink during cable operation. This allows for improved heat dissipation from the conductor to the coolant during cable operation. During cable operation, the coolant typically has a lower temperature than the conductor of at least one core.

[0029] The coolant is located in the cavity of the coolant guide and is optionally actively pumped through the coolant guide during cable operation. The coolant guide comprises or consists of sheathing material and forms a tube. The coolant guide contains the coolant in its cavity, which is enclosed by the sheathing material. The sheathing material comprises a polymeric material and may preferably consist of the heat transfer layer. If the sheathing material consists of the heat transfer layer, improved heat transfer within the cable is enabled. The coolant guide can optionally be located within a conductor, in which case the coolant guide may be surrounded by the conductor of the conductor, and the conductor, together with the coolant guide, may be enclosed by the conductor insulation.

[0030] The coolant guide can have a tensile strength, measured according to the method described above, of at least 10 MPa, preferably at least 15 MPa, and particularly preferably at least 20 MPa.

[0031] The coolant routing can exhibit sufficient cold flexibility to pass a cold winding test according to ISO 19642 at -40 °C.

[0032] The coolant can be a liquid suitable for use in cooling systems. The coolant can include water. The coolant can include alcoholic compounds.

[0033] The heat transfer layer comprises at least one polymer. The expression "at least one polymer" "This means that more than one type of polymer may be present. The polymer may include polyurethane, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, styrene-isoprene rubber, polyethylene terephthalate, polyamide, polystyrene, polyester, polyether, polycarbonate, or a mixture thereof.

[0034] The heat transfer layer comprises at least one inorganic filler with a hydrophobic surface modification. The inorganic particles of the filler, together with the surface modification, form a core-shell structure with a bulk-forming inorganic material in the interior and an outer shell consisting of the hydrophobic surface modification, which is typically present as a single layer on the particles. The inorganic material predominates by weight over the surface modification.

[0035] The inorganic fillers are present in the heat transfer layer in a total proportion of 35 to 65 wt.% relative to the heat transfer layer.

[0036] The inorganic filler can have a specific thermal conductivity, measured according to DIN EN ISO 22007-1:2018-03 (method using a heat flow plate device; preferably measured with a TA Instruments FOX 50 test device), of at least 25 W / (m·K). The bulk-forming inorganic material of the inorganic filler can be selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbonates, metal sulfates, metal phosphates and mixtures thereof, preferably comprising or, more preferably, consisting of metal hydroxides, metal oxides and mixtures thereof, and preferably comprising aluminum oxide.

[0037] The metal in the inorganic material can be selected from the group consisting of Al, Mg, Ca, B, Si, Zn, Ba, Sr, Fe, Mn, Cr, Sb, and Pb, and preferably includes Al. The inorganic material of the inorganic filler does not contain any hydrocarbon compounds.

[0038] The inorganic filler can have a particle size distribution with D50 of 1.3 - 2.0 µm, preferably of 1.4 - 1.8 µm, and particularly preferably of 1.6 µm, and with D100 of 15 - 25 µm, preferably of 18 - 22 µm, and particularly preferably of 20 µm, measured by laser diffraction, preferably measured with a " Mastersizer 2000 " Malvern Panalytical with ethanol (95%) as eluent. The inorganic filler can have a specific surface area of ​​2.0 - 5.0 m² / g, preferably 2.5 - 4.5 m² / g, particularly preferably approximately 3.5 m² / g, measured according to ISO 9277:2010 with nitrogen (N₂).

[0039] The inorganic filler has a hydrophobic surface modification.

[0040] The surface modification can be achieved by treating the surface of the inorganic material of the inorganic filler with a suitable reagent. The reagent can comprise a silane with at least one silicon-carbon bond, and preferably vinylsilane. The reagent reacts with an oxygen or nitrogen atom on the surface of the inorganic material of the inorganic filler, preferably forming a covalent bond. Depending on the type of inorganic material of the inorganic filler, the covalent bond can be formed between the silicon of the reagent and oxygen on the surface, or between the silicon of the reagent and nitrogen on the surface.

[0041] In this process, a surface modification is formed. This modification can comprise a silane with at least one silicon-carbon bond, and preferably a vinylsilane. The surface modification can preferably be covalently bonded to the surface of the inorganic filler material, forming either a silicon-oxygen bond or a silicon-nitrogen bond, depending on the type of inorganic filler material. The hydrophobic surface modification has a different chemical composition than the inorganic filler material to which it is bonded. The use of such a surface modification allows for the maintenance of mechanical properties despite high levels of inorganic filler in the polymer. Depending on the type of polymer used, it may be necessary to adapt the surface modification of the inorganic filler.The reagent for forming the surface modification must be selected according to the polymer used. Choosing an inorganic filler and a polymer with similar hydrophobicity is advantageous. A suitable combination is characterized by a homogeneous mixture of filler and polymer.

[0042] The heat transfer layer can be produced by compounding the polymer with the filler, preferably on a machine with a co-rotating twin screw.

[0043] The cable according to the invention described herein enables an increase in the achievable current output through efficient dissipation of the waste heat generated in the conductor, whereby the surface temperature of the cable during operation is lower than in an identical cable without a heat transfer layer. For example, a cable according to the invention can be designed such that, at a current of 525 A, measured on a cable with a nominal conductor cross-section of at least 25 mm², a temperature of 70 °C, preferably 60 °C, and particularly preferably 55 °C, is not exceeded.

[0044] The cable according to the invention can be used in mobile applications, in particular as a traction cable and as a charging cable for electric vehicles and electric aircraft. During operation of the cable, electrical energy is conducted through the cable and preferably a coolant is transported through the coolant channel.

[0045] The present invention further describes a hose comprising a polymer comprising or consisting of polyurethane, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, styrene-isoprene rubber, polyethylene terephthalate, polyamide, polystyrene, polyester, polyether, polycarbonate, or a mixture thereof. The hose comprises one or more inorganic fillers in a proportion of 35 to 65% by weight, based on the weight of the hose, comprising or consisting of at least one selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbonates, metal sulfates, metal phosphates and mixtures thereof, preferably metal hydroxides, metal oxides and mixtures thereof, and preferably aluminum oxide.The one or more inorganic fillers have a hydrophobic surface modification, wherein the surface modification comprises a silane with at least one silicon-carbon bond, and preferably vinylsilane. The hose has a specific thermal conductivity, measured according to DIN EN ISO 22007-1:2018-03 (method using a heat flow meter; preferably measured with a TA Instruments FOX 50 test device), of more than 0.2 W / m²K, preferably more than 0.3 W / m²K, and particularly preferably more than 0.35 W / m²K. The hose has a specific volume resistivity, measured according to ISO 19642, of at least 10 GΩ·mm at 20 °C, preferably at least 12 GΩ·mm, and particularly preferably at least 15 GΩ·mm at 20 °C. The hose has a tensile strength, measured according to DIN EN 60811-501, of at least 10 MPa, preferably at least 15 MPa, and particularly preferably at least 20 MPa.The hose exhibits sufficient cold flexibility to pass a cold coiling test according to ISO 19642 at -40 °C. The hose is leak-proof and therefore suitable for conveying and containing gases and / or liquids.

[0046] In one embodiment, the coolant line is a hose as described above.

[0047] The present invention further relates to a cable containing one or more hoses according to the invention as described above. A coolant, preferably a cooling liquid, can be transported in the at least one hose.

[0048] Furthermore, the present invention relates to a cable according to the invention, and preferably to an outer sheath made of an insulating plastic, which encloses the at least one conductor and the at least one cooling hose.

[0049] The present invention also describes a method for heat flow management of a cable according to the invention. The cable is provided in an embodiment as described herein, electrical energy is transmitted through the cable, and a suitable coolant, preferably a cooling liquid, is actively transported through the at least one coolant channel during operation of the cable. Description of the characters

[0050] Figure 1: Figure 1 shows an internally cooled single wire. Figure 2: Figure 2 shows a cable with internally cooled conductors. Figure 3: Figure 3 shows a cable with externally cooled conductors.

[0051] Figure 1Figure 1 shows an internally cooled single conductor (1) with a coolant guide (4) that encloses a cavity (5) through which a coolant can be transported. The coolant guide (4) consists of the heat transfer layer and is shaped like a tube. The coolant guide (4) is surrounded by a conductor (3). The single conductor (1) is enclosed by conductor insulation (2).

[0052] Figure 2 Figure 6 shows a cable (6) according to the present invention with two internally cooled conductors (1). The internally cooled conductors comprise a conductor (3) that surrounds the coolant guide (4). The coolant guide (4) consists of the heat transfer layer and is a tube. The cable further comprises another conductor (9) with a conductor (3) and conductor insulation. The cable contains several signal lines (8). The cable is enclosed by an outer sheath (7).

[0053] Figure 3Figure 1 shows a cable (10) according to the present invention with several externally cooled conductors (9), each comprising a conductor (3) and conductor insulation. The cable contains three coolant channels (4), each enclosing a cavity (5). The coolant channels (4) consist of the heat transfer layer and each form a tube. The cable contains several signal lines (8). The cable is enclosed by an outer sheath (7). Examples

[0054] The following section outlines the material adjustments, the computationally possible improvements and the improvements actually measured on a prototype with regard to current-carrying capacity through application of the concept according to the invention. The following measurement methods were used: Method 1: Tensile strength and elongation at break

[0055] According to DIN EN 60811-501: 2019. Test on standard-sized rod specimen; thickness test range 1 mm; tensile speed 25 mm / min for PE-X; 250 mm / min for all other materials. Method 2: Surface area determination using BET

[0056] According to ISO 9277:2010. Measurement with nitrogen. Method 3: Thermal conductivity

[0057] According to DIN EN ISO 22007-1: 2018-03. Method using heat flux plate measuring device; test instrument TA Instruments FOX 50.

[0058] Alternatively, determination by means of a heat flow meter (ISO8301; Heat Flow Meter "HFM") and / or plate meter (ISO8302; Guarded Hot Plate "GHP"). Method 4: Particle size determination

[0059] Laser diffraction, optionally Mastersizer 2000 (Malvern Panalytical) or CILAS 1064 (3P Instruments); Eluent Ethanol 95%. Method 5: Contact resistance

[0060] According to ISO 19642 Method 6: Cold Wrap Test

[0061] According to ISO 19642. 4 h at -40 °C, weight: 5 kg, speed: 1 s -1< , mandrel diameter: 21.5 mm. Method 7: Electrical breakdown test

[0062] Performed with 1 min / 1 kV. Example 1: Material-related adjustments

[0063] The starting point for these exemplary considerations is the TPE-U compound Elastollan 3090 HPM from BASF Polyurethanes, which is used, for example, as a sheathing material for cables of temperature class D according to ISO 6722. This is a thermoplastic polyurethane for continuous operating temperatures up to 150 °C with excellent resistance to hydrolysis; its soft phase is based on a macromolecular carbonate ester. It therefore possesses the necessary low-temperature flexibility as well as thermal resistance.

[0064] The following properties were considered for the TPE-U compound Elastollan 3090 HPM: Tensile strength: 54 MPa, Elongation at break: 525 %, Thermal conductivity: 0.22 Wm -< 1K -1< .

[0065] To ensure its suitability as a cooling hose, the objective is to achieve an optimal compromise between increased thermal conductivity and mechanical properties (tensile strength, elongation at break).

[0066] The TPE-U compound Elastollan 3090 HPM was supplemented with aluminum oxide (Martoxid TM-2250) from Martinswerk, which featured a compatibilizing surface modification based on vinylsilane, at concentrations of 40, 50, 60, and 70 wt%. The following changes resulted with regard to the property spectrum described above: Fill level, wt.% 0 40 50 60 70 Tensile strength, MPa 54 34 24 16 11,8 Elongation at break 525% 822% 709% 542% 58% Thermal conductivity, 0,22 0,36 0,49 0,58 0,69 Wm -1< K -1<

[0067] This resulted in an increase in thermal conductivity of 63% to 213%. Additionally, and unexpectedly, a significant improvement in elongation at break was observed for dosages of 40 wt% and 50 wt%. However, since dosages above 50 wt% could only be produced at very low throughput and the tensile strength also fell below the initial value, only the 40% and 50% variants were considered for further analysis. Example 2: Cold coil test and electrical breakdown test

[0068] In this example, the heat transfer layer according to the invention consists of 50 wt% of the polymer TPE-U 1195 A10 and 50 wt% of the filler material TM-2250 and has the form of a conductor insulation. A conductor insulation made of the same polymer without filler was used for comparison.

[0069] No breaks occurred in either the inventive conductor insulation or the comparison object during the cold coiling test, and the electrical breakdown test was passed. Object Wire insulation made of heat transfer layer (fill level 50 wt.%) Wire insulation without filler according to standard type ISO 6722-1:2011 ISO 6722-1:2011 FLY-6.0mm 2< FLY-6.0mm 2< Specification Measurement result Specification Measurement result Method 6 no cracks, no breaks no cracks, no breaks no cracks, no breaks no cracks, no breaks Method 7 no breakthrough no breakthrough no breakthrough no breakthrough Example 3: Calculatively possible improvements

[0070] The potential of the present invention disclosure will be demonstrated with specific reference to the hose materials shown in Example 1, using thermal simulations of selected cooled conduit constructions. This involves an internally cooled single-core cable of the type "Hivocar Cool" ( Fig. 1 ), to use a multi-core EVC (Electric Vehicle Charging) charging cable with internally cooled power conductors ( Fig. 2 ) as well as with externally cooled power lines ( Fig. 3 ).

[0071] In the case of the internally cooled single conductor, the use of the heat transfer layer as hose material results in an improvement in current carrying capacity of 45 - 80% compared to the state without a heat transfer layer.

[0072] In the case of the internally cooled EVC line, a calculated improvement of 43-70% results compared to the state without a heat transfer layer.

[0073] In the case of the externally cooled EVC cable, a calculated improvement of approximately 7–10% is achieved compared to the condition without a heat transfer layer. This demonstrates the significantly negative impact of poorly thermally conductive polymers and the benefit of the inventive concept of material-based thermal management. Furthermore, if the conductors and hoses are located in a common, highly thermally conductive polymeric cable filler material, instead of in a loose stranded bundle, a significant improvement compared to the condition without a heat transfer layer is possible due to improved coupling of the waste heat into the hoses.

[0074] The calculations and simulations clearly demonstrate the advantages of the concept: A significant increase in current-carrying capacity is possible, particularly with direct contact between the heat source (copper conductor) and the cooling hose. This is achievable using common and well-known hose materials, such as TPE-U. The calculations will be verified on prototypes below. The internally cooled single conductor, as in Fig. 1 It was presented and investigated. Example 4: Implementation of the concept on a selected prototype

[0075] Based on the reasons outlined in Example 3, two variants of an internally cooled single conductor were manufactured and measured, each with a nominal conductor cross-section of 25 mm². Type A was constructed using the standard tubing made of the material "XLPE T4-POLYEV". "The cooling hose, type B, supplied by ACI, was filled with the TPE-U described in Example 1, which was 50% by weight. Under current-controlled measurement, the following reductions in surface temperature were observed at defined current strengths. Surface temperature Current through conductor 400 A 500 A 525 A XLPE T4-POLYEV (average) 46 °C 63 °C 67 °C TPE-U - 50% filled 37 °C 48 °C 51 °C Change in temperature -37% -35% -35% Summary

[0076] The inventive concept of material-based thermal management for cooled pipes is fundamentally based on replacing conventional, poorly thermally conductive hose materials with comparable polymer types possessing similar mechanical and electrical properties, but with significantly improved heat dissipation achieved through modification with a highly thermally conductive filler. Example 1 demonstrates, using a TPE-U as an example, that such a modification was achieved while largely maintaining or even improving the tested mechanical properties. Since compatibility is based on the selection of the respective surface modifier for the filler, the available data indicate that the inventive concept is applicable to other hose materials (e.g., XLPE, PVC, SiR).

[0077] Examples 3 and 4 demonstrate the feasibility and potential of the concept both theoretically and practically, also illustrating the necessary targeted heat conduction: Simply replacing the tubing material of an externally cooled EVC cable results in a relatively small increase in current-carrying capacity compared to internally cooled types. Further improvement can be achieved by creating a heat conduction path, for example, using a thermally conductive cable filler.

Claims

1. Cable comprising: a) at least one core, each core comprising a conductor and core insulation surrounding the conductor, b) at least one coolant channel, the cable comprising an electrically insulating heat transfer layer, the heat transfer layer comprising: i) at least one polymer, and ii) one or more inorganic fillers in a proportion of 35 to 65 wt.%, based on the weight of the heat transfer layer, the one or more inorganic fillers having a hydrophobic surface modification, the heat transfer layer being used (i) as the sheathing material of the at least one coolant channel, (ii) as the core insulation of the at least one core, and / or (iii) as the solid cable filler material surrounding the at least one core and the at least one coolant channel.

2. The cable according to claim 1, wherein one or more inorganic fillers have a specific thermal conductivity of at least 25 W / m². -1 K -1 exhibits and / or the heat transfer layer is in direct contact with the conductor of the at least one wire and / or the coolant of the at least one coolant guide.

3. The cable according to claim 1 or 2, wherein the heat transfer layer has a specific thermal conductivity of more than 0.2 W / m²K -1 K -1 exhibits.

4. The cable according to any of the preceding claims, wherein the heat transfer layer has a specific volume resistance of at least 10 GΩ·mm at 20 °C, measured according to ISO 19642.

5. The cable according to any of the preceding claims, wherein the heat transfer layer and / or the coolant guide has a tensile strength, measured according to DIN EN 60811-501, of at least 10 MPa.

6. The cable according to any of the preceding claims, wherein the coolant guide has sufficient cold flexibility such that said coolant guide passes a cold winding test according to ISO 19642 at -40 °C.

7. The cable according to any of the preceding claims, wherein the polymer comprises or consists of polyurethane, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, styrene-isoprene rubber, polyethylene terephthalate, polyamide, polystyrene, polyester, polyether, polycarbonate, or a mixture thereof.

8. The cable according to any of the preceding claims, wherein the heat transfer layer comprises the polymer in a proportion of 35 to 65 wt.% based on the weight of the heat transfer layer; and / or wherein the inorganic filler comprises or consists of at least one selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbonates, metal sulfates, metal phosphates and mixtures thereof, preferably metal hydroxides, metal oxides and mixtures thereof, and preferably aluminum oxide.

9. The cable according to one of the preceding claims, wherein the inorganic filler has a particle size distribution with D50 of 1.3 - 2.0 µm and with D100 of 15 - 25 µm, measured by laser diffraction, and / or a specific surface area of ​​2.0 - 5.0 m² 2 / g, measured according to ISO 9277:2010 using nitrogen.

10. The cable according to any of the preceding claims, wherein the surface modification of the inorganic filler comprises a silane with at least one silicon-carbon bond, and preferably comprises vinylsilane; and / or wherein the surface modification is covalently bonded to the surface of the inorganic filler.

11. The cable according to one of the preceding claims, wherein the surface temperature of the cable is measured at a power current of 525 A on a cable with a conductor cross-section of at least 25 mm². 2 , does not exceed a temperature of 70 °C.

12. The cable according to one of the preceding claims, for use in mobile applications, in particular as a traction cable and as a charging cable for electric vehicles and electric aircraft.

13. Hose comprising a polymer comprising or consisting of polyurethane, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, styrene-isoprene rubber, polyethylene terephthalate, polyamide, polystyrene, polyester, polyether, polycarbonate, or a mixture thereof, and one or more inorganic fillers in a proportion of 35 to 65 wt.-%, based on the weight of the hose, comprising or consisting of at least one selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbonates, metal sulfates, metal phosphates and mixtures thereof, preferably metal hydroxides, metal oxides and mixtures thereof, and preferably comprising aluminum oxide, wherein one or more inorganic fillers have a hydrophobic surface modification, wherein the surface modification comprises a silane with at least one silicon-carbon bond, and preferably comprises vinylsilane, wherein the hose i) has a specific thermal conductivity of more than 0.2 Wm. -1 K -1, ii) a specific volume resistivity of at least 10 GΩ·mm at 20 °C, measured according to ISO 19642, iii) a tensile strength, measured according to DIN EN 60811-501, of at least 10 MPa, and iv) has sufficient cold flexibility so that the hose passes a cold coiling test according to ISO 19642 at -40 °C.

14. Cable comprising a hose according to claim 13.

15. Method for heat flow management of a cable, comprising a) the provision of a cable according to any one of claims 1-12, b) the transmission of electrical energy through the cable, c) the active transport of a suitable coolant, preferably a cooling liquid, through which at least one coolant guide is provided during the operation of the cable, wherein the surface temperature of the charging cable at a power current of 525 A, measured on a cable with a conductor cross-section of at least 25 mm² 2 , does not exceed a temperature of 70 °C.

Images