The invention relates to a heat exchanger.
US 2007 15 85 84 A has disclosed a heat sink comprising a main body from which a multiplicity of carbon nanotubes extend.
In the field of electrical engineering, especially in high performance electronics, output peaks which result in large amounts of heat from the high performance electronic components occur during operation, for example in electric vehicles. These amounts of heat must be dissipated. This has hitherto been achieved through liquid cooling. Such cooling systems are complex and costly, since the necessary components such as cooling circuit, cooling water and pump generate considerable additional weight and considerable costs.
The invention relates to a heat exchanger having a main body which is in thermal communication with carbon nanostructure-based fibers which are especially produced from carbon nanotubes or graphene/graphite platelets. At least one gas channel which is at least partially formed by the main body is provided, wherein the carbon nanostructure-based fibers at least in regions extend in the gas channel. The gas channel results in very efficient cooling. The invention is elucidated hereinbelow with reference to a cooling. However, the invention also encompasses the configuration in the form of a heating, i.e. in such a case a component in thermal communication with the main body is heated by means of a gas heating stream flowing through the gas channel. In the case of cooling, a component to be deheated in thermal communication with the main body, in particular a high performance electronic element, emits its heat to the main body, i.e. the gas channel, wherein the gas channel, more particularly: at least one portion of a wall of the gas channel, transfers the heat to the carbon nanostructure-based fibers which at least in regions are present in the gas channel. The deheating according to the invention of high performance electronics is thus preferably carried out against the ambient air as the heat sink. An optional medium channel uses cooling liquid (coolant) to pass the heat from the high performance electronics to the gas channel. In the gas channel, the heat is transferred from the fibers into the gas/the air. The main body is in thermal communication with the carbon nanostructure-based fibers/yarns. The term “gas channel” describes the channel in which the carbon nanostructure-based fibers are located. The very large surface area greatly facilitates heat transfer into the gas (in particular air) and thus increases efficiency. The medium channel is in particular liquid-traversable. It serves to connect a heat source with the heat sink (i.e. the gas channel). Forced convection of the coolant is especially employed, preferably a blower which blows for example air through the medium channel, in particular gas channel, so that the recited disadvantages of liquid cooling do not occur. The invention nevertheless achieves very effective and cost-efficient cooling.
A development of the invention provides that the carbon nanostructure-based fibers extend along the cross section, in particular a cross-sectional area, preferably cross-sectional plane, of the gas channel, wherein the cross section extends transversely, in particular perpendicularly, to the longitudinal extent of the gas channel. As a result of this configuration, the cooling medium stream, in particular the cooling air, impacts the carbon nanostructure-based fibers transversely, thus achieving very good heat dissipation.
In a preferred development of the invention, the heat exchanger is directly connected to a heat source. The heat source is for example in direct contact with a wall section of the heat exchanger to ensure direct heat transfer from the heat source to the heat exchanger. Alternatively, the heat exchanger preferably comprises—as mentioned previously—a medium channel which is traversable or traversed by a cooling liquid for indirect connection to the heat source. The cooling liquid transports the heat from the heat source to the heat exchanger and thus provides the indirect connection. The cooling liquid advantageously flows in the direction from the heat source to the heat exchanger.
A development of the invention provides that the carbon nanostructure-based fibers at least in regions extend substantially parallel to one another. The carbon nanostructure-based fibers thus form a kind of parallel structure in the gas channel.
It may preferably be provided that the carbon nanostructure-based fibers form a net, preferably in the manner of a wire mesh. In this case, a network structure then takes the place of the recited parallel structure.
It may especially be provided that the carbon nanostructure-based fibers form a braid. The fibers are braided with one another, thus also providing them with improved mechanical stability and ensuring they are not deformed by the gas stream.
It may preferably be provided that the carbon nanostructure-based fibers form a weave.
It is preferably provided that the carbon nanostructure-based fibers form a knit.
The various measures such as for example the braid, the weave or the recited knit ensure a particularly large surface area of the structure formed by the carbon nanostructure-based fibers in the gas channel, thus improving heat dissipation.
It is advantageous when the carbon nanostructure-based fibers are directly connected to the main body. In such a case, the main body can directly emit its heat to the carbon nanostructure-based fibers.
It may preferably be provided that the carbon nanostructure-based fibers are held by a thermally conductive holder body which is arranged in the gas channel and is in thermal communication therewith. During construction of the heat exchanger, the carbon nanostructure-based fibers are thus secured to a holder body, wherein the latter is in turn arranged in the gas channel. This simplifies production. When arranging the holder body in the medium channel, said holder body is put into thermal communication with the latter so that the main body can transfer its heat to the holder body and said holder body can transfer to the carbon nanostructure-based fibers.
The holder body may preferably be configured as a holder frame. This holder frame is then “strung” with the carbon nanostructure-based fibers.
A development of the invention provides that a plurality of holder bodies and/or cross sections, in particular cross-sectional areas, formed by carbon nanostructure-based fibers are serially arranged in the gas channel along the longitudinal extent thereof. The plurality of holder bodies/plurality of cross sections altogether achieve a correspondingly large surface area of the carbon nanostructure-based fibers, with the result that the heat can be very well dissipated.
The invention is elucidated with reference to exemplary embodiments in the figures, in which:
The gas channel 3 has a cross section 9. Located in a cross-sectional plane 10 which extends perpendicularly to the longitudinal extent of the gas channel 3 are a multiplicity of carbon nano-based fibers (CNB) which are in the form of carbon nanotubes (CNT). In the exemplary embodiment of
Arranged on the outside of the gas channel 3, in the exemplary embodiment of
The exemplary embodiment of
Not shown is an exemplary embodiment which corresponds to
The exemplary embodiment of
The exemplary embodiment of
The invention is especially employable in the field of electric vehicles, namely for cooling output peaks of high performance electronic components. It is preferable when forced convection of air is generated in the medium channel 3 using a blower. The large heat exchanger surface area generated by the carbon nanostructure-based fibers (CNB) is advantageous, this ensuring very good heat transfer from the solid to the flowing gas, especially to the flowing air. It is preferable to employ carbon nanostructure-based fibers (CNB), in particular fibers composed of CNT or graphene platelets, having a diameter of 5 μm and especially having a thermal conductivity >800 W/mK. In addition, such a material has a very high tensile strength >1 GPa, thus making it possible to realize very delicate structures having sufficient resilience. It is further advantageous that textile methods, such as knitting, braiding or weaving, may be employed to achieve structures with the carbon nanostructure-based fibers (CNB) through which the cooling medium, namely the cooling gas, in particular the air, may flow. Such textile elements are also particularly amenable to prefabrication.
Employed for example is a heat exchanger 1 provided with a holder frame 13, wherein the holder frame 13 has a width of 10 cm and a height of 3 cm. Said frame can accommodate preferably 2000 windings of the carbon nanostructure-based fibers (CNB). These carbon nanostructure-based fibers (CNB) especially have a diameter of 10 μm. Such a holder frame 13 results in a heat exchanger surface area of 0.0037 m2. When about 30, preferably 33, such holder frames 13 are serially arranged in a medium channel 3 of a heat exchanger 1, this results in a heat exchanger surface area of 0.124 m2. This makes it possible to realize an effective heat exchanger 1 even in a small space and by the simplest means of production.
The same applies to heat exchangers 1 which comprise carbon nanostructure-based fibers (CNB) in the form of a braid of a net cloth (in particular wire mesh) or which comprise a knit or weave. A knit or weave preferably comprises numerous weft threads, since these form a direct connection with the medium channel 3.
The highly efficient heat exchangers 1 according to the invention are—as mentioned—employable especially in high performance electronics. However, further applications include air-conditioning systems, household appliances and the like. As mentioned hereinabove, such heat exchangers 1 are suitable not only for cooling, but also for heating.
Number | Date | Country | Kind |
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10 2018 218 826.2 | Nov 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/077755 | 10/14/2019 | WO | 00 |