DE102011082204A1 - Thermoelectric unit for converting heat into electric current in electrically-driven motor car, has thermoelectric elements arranged between differently oriented outer sides of inner and outer fluid guide elements - Google Patents

Abstract

The thermoelectric unit (100) has an inner fluid guide element (110) in which fluid channels (120) are arranged. Each of the fluid channels is arranged in two outer fluid guide elements (140). Two thermoelectric elements (130) i.e. Peltier elements, are arranged between an outer side of the inner fluid guide element and a differently oriented outer side of the outer fluid guide elements. The inner and outer fluid guide elements have material blocks i.e. metal blocks in which apertures or holes are formed as the fluid channels.

Description

The present invention relates to a thermoelectric unit according to the main claim.

In the electrically powered motor vehicle, for example, the battery, power electronics and electric machine experience waste heat, which must be dissipated at a moderate temperature level. Under certain environmental conditions, these components must also be heated. This can be done in a self-sufficient way, i. H. independent of the air conditioner, via Peltier elements that can be switched only by reversing the current flow between cooling and heating. By means of such an apparatus with two coolant sides (ie via a warm fluid and a cold fluid), the components to be tempered can be connected on one side and, for example, a contact to the environment can be established on the other side (eg cooler in the front module a vehicle). Alternatively, if no Peltier elements are used, the "apparatus" can be a chiller through which coolant and refrigerant flow, but would then be thermally coupled to the conventional air conditioning system again.

The basic problem of such a plant is that the efficiency of the Peltier effect with small adjacent temperature differences (eg 10 K) can certainly keep up with the efficiency of conventional evaporative refrigeration systems, with larger temperature differences, which unfortunately usually the usage profile but are significantly inferior very quickly. This means that the heat transfer between Peltier element and fluid should be optimally designed so that only small, additional temperature losses occur. This problem also high heat flux densities escape, especially when working with a few high-performance elements instead of many standard elements. High-performance elements can be accommodated in a small space if a high heat transfer to the fluid is forced by a high pressure drop.

A disadvantage of the prior art that either many Peltier elements must be used (for example, in terms of space, cost, etc.), or using high-performance elements, a high pump pressure is required, which is normally not applied in the vehicle. For example, an exemplary electric coolant pump provides a maximum of 0.8 bar pressure build-up even at low speeds / throughputs, and this must be sufficient for several components through which flow is effected, including lines.

It is the object of the present invention to provide an improved thermoelectric unit.

This object is achieved by a thermoelectric unit according to the main claim.

• – einem inneren Fluidführungselement, das eine Mehrzahl von Außenflächen aufweist und in dem mehrere Fluidkanäle angeordnet sind;
• – zumindest zwei äußeren Fluidführungselementen, in welchen je mehrere Fluidkanäle angeordnet ist; und
• – zumindest zwei thermoelektrische Elemente, die je zwischen einer der Außenseiten des inneren Fluidführungselementes und einer Außenseite eines unterschiedlichen der äußeren Fluidführungselemente angeordnet sind.

The present invention provides a thermoelectric unit having the following features:

• - An inner fluid guide element having a plurality of outer surfaces and in which a plurality of fluid channels are arranged;
• - At least two outer fluid guide elements, in each of which a plurality of fluid channels is arranged; and
• - At least two thermoelectric elements, which are each arranged between one of the outer sides of the inner fluid guide element and an outer side of a different one of the outer fluid guide elements.

In this case, a thermoelectric element can be understood as meaning a semiconductor component which is capable of converting heat into electrical current and, conversely, also converting electrical energy into heat.

The invention is based on the finding that an optimum flow of heat from the fluid channels of the outer fluid-guiding element to fluid channels of the inner fluid-guiding element can now take place through an arrangement of fluid channels in different fluid-guiding elements and a corresponding arrangement of thermoelectric elements. This is ensured by the fact that now the thermoelectric elements are no longer arranged only on two (main) surfaces of the inner fluid guide element, but on different sides d. H. Outer surfaces of the inner fluid guide element. It is particularly advantageous if the thermoelectric elements are arranged at an angle from an angular range to each other, wherein, for example, the angle range angle of 5 degrees to 90 degrees. In this way it can be made possible that the thermoelectric elements are attached to differently oriented outer surfaces of the inner fluid guiding element, which are not only formed by two opposing main surfaces of the inner fluid guiding element. In this way, the three-dimensional propagation of heat in the inner fluid guiding element can be exploited very favorably to dissipate this heat efficiently and at least partially converted into electrical energy in the thermoelectric elements.

The present invention offers the advantage of good thermodynamics at high heat flux densities. At the same time, a special favorable production method and a high modularity of a thermoelectric system to be created and a simple connection possibility of the presented here thermoelectric unit to further fluid-carrying components possible.

It is particularly advantageous for a thermoelectric element to be arranged on more than two outer surfaces along a circumference of the inner fluid guiding element, each of which is in thermal contact with an outer surface of an outer fluid guiding element, in particular a thermoelectric element on each outer surface of the inner fluid guiding element on each of the thermoelectric elements, an outer fluid guide element is arranged. Such an embodiment of the present invention offers the advantage of a very advantageous possibility for heat transfer, since the inner fluid guide element can accommodate a large number of individual fluid channels (three-dimensional package construction instead of two-dimensional, thin fluid guidance layers). In operating states in which the inner fluid guiding element is connected to the warm side of the Peltier elements, this advantage is particularly effective since the heat output to be dissipated corresponds to the sum of the cooling capacity of the outer fluid guiding elements and the electric power to be expended and thus to the power to be transmitted significantly exceeds the outer fluid guide elements.

Also advantageous is an embodiment of the present invention, wherein the inner fluid guide element consists of a block of material, in particular a metal block, in which openings or bores are introduced as fluid channels and / or at least one outer fluid guide element consists of a block of material, in particular of a metal block , in which openings or bores are introduced as fluid channels. Such an embodiment of the present invention offers the advantage of a particularly simple and thus inexpensive manufacturability of the inner or / the outer fluid guide elements (s), whereby the entire thermoelectric unit can be made inexpensively and still very functional with respect to a heat transfer property.

Particularly efficient in terms of heat transfer from the inner fluid guide element or into the inner fluid guide element is a thermoelectric element in which the inner fluid guide element has a cubic shape.

In order to ensure a simple supply of the fluid into the fluid channels, the fluid channels of the inner fluid guide element can be arranged parallel to the fluid channels of the at least one outer fluid guide element.

Also, according to another embodiment of the present invention, the inner fluid guide member may have a hexagonal or octagonal shape in cross section normal to a fluid flow direction of a fluid in the fluid passages. Also, such an embodiment of the present invention provides the advantage of good heat flux density, such that a high amount of heat from the fluid flowing through the fluid passages of the inner or outer fluid guide element can be transmitted through the thermoelectric elements to the inner or outer outer fluid guide elements.

In order to achieve the largest possible packing density of fluid channels in the inner fluid guide element and thus a high transmission power and a homogeneous heat density as possible on the outer surfaces of the inner fluid guide element, the fluid channels may be arranged in the form of a matrix in a plurality of rows and columns in the inner fluid guide element.

Good heat dissipation in the outer fluid guide elements can be achieved if, according to a further embodiment of the present invention, the fluid channels are arranged in at least one of the outer fluid guide elements, in particular in all outer fluid guide elements, in a single row and a plurality of columns.

A particularly good property for heat transfer can be achieved if the fluid channels of the inner fluid guide element and / or at least one of the outer fluid guide elements have a circular and / or circular cross section and / or a cross section with recesses, in particular a star-shaped cross section.

According to their present use for pumping heat, the thermoelectric elements have been advantageously designed for their application as Peltier elements.

• – einer ersten thermoelektrischen Einheit, wie sie vorstehend beschrieben wurde; und
• – einer zweiten thermoelektrischen Einheit wie sie vorstehend beschrieben wurde,

wobei die Fluidkanäle des inneren Fluidführungselementes der erste thermoelektrischen Einheit mit den Fluidkanäle des inneren Fluidführungselementes der zweiten thermoelektrischen Einheit verbunden sind und die die Fluidkanäle zumindest eines äußeren Fluidführungselementes der ersten thermoelektrischen Einheit mit den Fluidkanäle zumindest eines der äußeren Fluidführungselemente der zweiten thermoelektrischen Einheit verbunden sind,
insbesondere wobei ein Klebematerial und/oder ein Dichtungsring zur Verbindung der Fluidkanäle des inneren Fluidführungselementes der ersten thermoelektrischen Einheit mit den Fluidkanälen des inneren Fluidführungselementes der zweiten thermoelektrischen Einheit und/oder zur Verbindung der Fluidkanäle zumindest eines äußeren Fluidführungselementes der ersten thermoelektrischen Einheit mit den Fluidkanälen zumindest eines der äußeren Fluidführungselemente der zweiten thermoelektrischen Einheit verwendet wird.According to another embodiment of the present invention can be achieved by a coupling of a plurality of thermoelectric units, as described above. Thus, a thermoelectric system with the following features is particularly advantageous:

• A first thermoelectric unit as described above; and
• A second thermoelectric unit as described above,

wherein the fluid channels of the inner fluid guiding element of the first thermoelectric unit are connected to the fluid channels of the inner fluid guiding element of the second thermoelectric unit and the fluid channels of at least one outer fluid guiding element of the first thermoelectric unit are connected to the fluid channels of at least one of the outer fluid guiding elements of the second thermoelectric unit,
in particular wherein an adhesive material and / or a sealing ring for connecting the fluid channels of the inner fluid guiding element of the first thermoelectric unit with the fluid channels of the inner fluid guiding element of the second thermoelectric unit and / or for connecting the fluid channels at least one outer fluid guiding element of the first thermoelectric unit with the fluid channels at least one the outer fluid guide elements of the second thermoelectric unit is used.

Advantageous embodiments of the present invention will be explained below with reference to the accompanying drawings. Show it:

1 a cross-sectional view through an embodiment of the present invention as a thermoelectric unit;

2 Side view of an embodiment of the present invention as a thermoelectric unit;

3 Top view of a thermoelectric system according to an embodiment of the present invention, which comprises a plurality of thermoelectric units according to the embodiment of the 1 respectively. 2 used;

4a a representation of a round (flow) cross-section of a fluid channel for use in an embodiment according to the present invention;

4b a representation of a star-shaped (flow) cross-section of a fluid channel for use in an embodiment according to the present invention; and

5 a cross-sectional view through another embodiment of the present invention as a thermoelectric unit.

In the following description of the preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various drawings and similar, and a repeated description of these elements will be omitted.

The invention presented here serves the purpose of shifting the (economically reasonable) performance limit of thermoelectric heaters / coolers towards higher transferable heat outputs and thereby to make do with small pressure losses in the fluid channels.

1 shows a cross-sectional view through an embodiment of the present invention as a thermoelectric unit 100 , Here is an inner fluid guide element 110 , which may also be referred to as a warm side body provided. At the in 1 shown thermoelectric unit 100 has the inner fluid guide element 110 a cubic, ie cube-shaped body, which is made for example of a solid material (ie, a block of material, such as a metal block) and with fluid channels 120 is traversed. The fluid channels are introduced in the inner fluid guide body, for example as a bore or opening, which extends through the solid material of the inner fluid guide element 110 extend. Alternatively, the fluid channels may also be formed as a rod press profile, wherein the inner fluid guide element 110 then should not be made of a solid material. The fluid channels 120 are matrix-shaped, ie in a plurality of columns and a plurality of rows in the inner fluid guide element 110 arranged. Furthermore, the thermoelectric unit 100 four thermoelectric elements 130 on, which are configured for example as a Peltier element. Each of these thermoelectric elements 130 is on another outer surface of the (cubic) inner fluid guide element 110 arranged along a circumference thereof. This means that on those sides of the inner fluid guide element 110 via which fluid into the fluid channels 120 flows, no thermoelectric element 130 is arranged to allow fluid flow into the fluid channels 120 not to hinder. At each of the thermoelectric elements 130 is still an external fluid guide element 140 arranged, wherein each of these outer fluid guide elements 140 at an inner fluid guide element 110 opposite side of the associated thermoelectric element 130 is arranged. The connections between the thermoelectric elements 130 and the inner fluid guiding element 110 and between the outer fluid guide elements 140 and the respective associated thermoelectric elements 130 is formed thermally conductive to the best possible heat transfer or heat dissipation or heat absorption from the inner fluid guide element 110 to ensure. The fluid guide channels 120 in the outer fluid guide element 140 are in a single line, but in arranged in several columns. As in the critical operating case of pumping heat from the outer fluid guide elements 140 over the thermoelekrischen elements 130 in the inner fluid guide element 110 The latter has a much larger amount of heat to absorb than the outer fluid guide elements 140 have to submit, sufficient for the outer fluid guide elements a smaller inner surface of fluid guide channels 120 and suffices (in a preferred embodiment) said single-line structure.

The preferably designed as high-performance Peltier elements thermoelectric elements 130 are thus attached to the circumference of a body which (in contrast to the more 2D shape such as a layer of sheet metal) comes close to a cubic shape. The cubic shape offers in contrast to z. B. a sheet has the advantage of uniform heat propagation in three dimensions. On the surface of a two-dimensional body, however, hot spots would form at the position of the Peltier elements, since the heat propagation in the plane would be limited by the low material thickness. This unit close to a cube, hereinafter referred to as "hot side body", is then of a high number of fluid channels 120 crossed, each having a small diameter. The pressure loss can be achieved by increasing the number of these channels 120 reduce, as this increases the flowed through total cross-sectional area. The laminarity and increasingly lower velocity of the flow in the channels 120 reduces the heat transfer, but due to the high number of channels 120 is overcompensated because of a high number of fluid channels 120 an increase in the heat transfer surface between the hot side body 110 and the fluid passing through the fluid channels 120 of the warm side body 110 flows.

The other fluid side is on the other side of the Peltier elements 130 and may consist of several, non-contiguous bodies 140 , hereinafter referred to as "cold side member" formed. Because these bodies 140 not in the same measure of several pages with Peltier elements 130 can be acted as the hot side body, these are to be acted upon with a lower heat flux density, which results from the energy balance (cold side heat flow = hot side heat flow minus electrical power) by itself.

2 shows side view of an embodiment of the present invention as a thermoelectric unit 100 , From the illustration according to 2 It can be seen that in the 2 invisible inner fluid guiding element along a plane of the drawing 2 directed in the scope of thermoelectric elements 130 with attached outer fluid guide elements 140 is surrounded. This is the Peltier element 130 that of the front outer fluid guide element 140 is hidden, shown in dashed lines. Through the fluid channels of the outer fluid guide elements 140 preferably flows a cold fluid 200 while through the fluid guide channels of the in the 2 invisible inner fluid guide element preferably a warm fluid 210 flows. In this case, a fluid can be understood as meaning a liquid or a gas which is designed as a temperature control medium for receiving or emitting heat.

3 shows a plan view of a thermoelectric system 300 according to an embodiment of the present invention, which comprises a plurality of thermoelectric units 100 according to the embodiment of the 1 respectively. 2 used. The individual thermoelectric units 100 are at junctions 310 by an adhesive material and / or a seal such as an O-ring connected to each other such that a fluid, which consists of the inner fluid guide element of a preceding in the flow direction thermoelectric unit 100 is passed in fluid channels of an inner fluid guide element of a downstream in the flow direction of the fluid thermoelectric unit. In contrast, by another connection point or connection 310 between two thermoelectric units 100 a fluid, which consists of one of the outer fluid guide element of a preceding in the flow direction thermoelectric unit 100 directed in fluid channels of one of the outer fluid guide elements of a post-flow downstream thermoelectric unit. At one end of the thermoelectric system 300 For example, a flange 320 (or collector) are also arranged by means of one of the above-described connection possibilities at a corresponding connection point to a fluid which is to flow through the matrix-like arranged fluid channels of the inner fluid guide element, the corresponding channels of the inner fluid guide element is supplied.

These connection points 310 or connections between individual thermoelectric units 100 and / or a flange 320 can be very simple and inexpensive to manufacture by applying the adhesive material and / or the introduction of the seal, so that the thermoelectric system 300 by the use of the thermoelectric elements described above 100 characterized by high modularity at low production costs.

4a shows a representation of a round (flow) cross-section 400 a fluid guide channel. Such a round cross section of a fluid channel may be in the inner and / or outer Fluid guide element used to guide a fluid. Such a round cross-section of a fluid channel has the advantage that such embodiments of a fluid guide channel can be implemented very easily and inexpensively through a bore in a material of the inner fluid guide element.

4b shows a representation of a star-shaped (flow) cross-section of a fluid channel. Such a designed fluid channel can also be used in the inner or outer fluid guide element and offers the advantage that such a fluid channel (although consuming in its production, the channel, however, has a significantly higher surface area and thus has a higher ability to heat exchange.

5 shows a cross-sectional view through another embodiment of the present invention as a thermoelectric unit 100 , In this case, the inner fluid guide element 110 no cubic form now; rather, the inner fluid guide element has 110 in cross-section on a shape of an octagon. At each of the eight outer surfaces of the inner fluid guide element 110 is a thermoelectric element 130 thermally conductive on the inner fluid guide element 110 appropriate. Each of the thermoelectric elements 130 is on an inner fluid guide element 110 opposite side thermally conductive with an outer fluid guide element 140 connected. Also, such an embodiment of the present invention provides advantageous properties in terms of optimizing the heat flow density and thus efficient use of the thermoelectric elements for energy conversion of a portion of the heat from the fluid flowing through the fluid channels of the inner fluid guide element.

In a reversal of the according to the 1 to 5 arranged thermoelectric elements, for example, to switch from a cooling case to a heating case, this arrangement of components of a thermoelectric unit 100 Of course no longer advantageous. However, experience has shown that this is not a problem, since far lower requirements are placed on the efficiency of the heating case (in the worst case, it is heated with COP = 1).

In the 1 and 5 Thus, two different embodiments of a thermoelectric unit 100 shown; in both cases, the relatively equivalent extent of the hot side body is given in all three spatial directions.

A particular aspect of the present invention can be seen in the fact that a high modularizability is given: In the flow direction, any number of individual modules 100 glued or braced by z. As adhesive or lying outside the thermoelectric unit threaded rods, each using centering pins for the exact passage of the channels (as shown in the 3 is shown by way of example). For ease of implementation, the channels should preferably not seal against one another at these connection levels, since thorough mixing within the same temperature zone (hot or cold fluid) is not problematic. A seal should be ensured only to the environment. The separation of the individual components of adjacent thermal units 100 can be carried out thermally conductive or thermally insulating. Most simple variants will be thermally insulating. A thermally insulating design also has the advantage that no heat conduction (ie no temperature compensation) takes place beyond the module boundaries and so z. B. the advantageous temperature control is ensured in a countercurrent flow of fluids.

Conventional layer construction requires a complex design of the collectors at the inlet and outlet. Such a complex collector omitted here, it results in a simple flange design 320 as related to 3 is shown. Individual flanges on the cold side (in the 3 not shown) can z. B. connected via a hose system with a branch.

The arrangement of the fluid channels (which, for example, are designed as bores) need not be uniform across the cross section of the bodies (i.e., the fluid routing elements), but can be thermodynamically optimized via the heat distribution in the body, such as according to corresponding FEM simulations.

The fluid channels do not need to be round as it is in the 4a is shown. A thermodynamically more advantageous shape can be chosen if this is acceptable from the manufacturing side (eg extrusion of channels with a star-shaped cross-section, as described in US Pat 4b is shown).

The present invention offers several advantages. For example, good thermodynamics and high heat flux densities can be realized. Also, a particularly favorable method of preparation by using z. B. extruded body and a high modularity can be achieved. Finally, a simple header design and / or flange connection also facilitates a connection or the connection of the fluid guide channels of the individual inner and / or outer fluid guiding elements.

The present description thus discloses, for example, a thermoelectric liquid / liquid heater & cooler. For this purpose, Peltier elements located in a heat exchanger pump heat from one side through which liquid flows to the other side through which liquid flows, thus cooling the first fluid and heating the second fluid. The side with the higher heat flux density to be transmitted is arranged centered between the Peltier elements and ensures a high homogenization of the heat input because of its cubic shape, which is why this design is particularly suitable for high-performance Peltier elements.

The described embodiments are chosen only by way of example and can be combined with each other.

LIST OF REFERENCE NUMBERS

100

thermoelectric unit

110

inner fluid guide element

120

Fluid guide channels

130

thermoelectric element, Peltier element

140

outer fluid guide elements

200

Flow direction of the cold fluid

210

Flow direction of the warm fluid

300

thermoelectric system

310

Joint, glue O-ring

320

Flange (on the warm side)

Claims (10)

Thermoelectric unit ( 100 ) having the following features: - an inner fluid guiding element ( 110 ) having a plurality of outer surfaces and in which a plurality of fluid channels ( 120 ) are arranged; At least two outer fluid guiding elements ( 140 ), in each of which a plurality of fluid channels ( 120 ) is arranged; and at least two thermoelectric elements ( 130 ), each between one of the outer sides of the inner fluid guide element ( 110 ) and an outer side of a different one of the outer fluid guiding elements ( 140 ) are arranged. Thermoelectric unit ( 100 ) according to claim 1, characterized in that on more than two outer surfaces along a circumference of the inner fluid guiding element ( 110 ) each a thermoelectric element ( 130 ), each of which is connected to an outer surface of an outer fluid guide element ( 110 ) is in thermal contact, in particular wherein on each outer surface of the inner fluid guide element ( 110 ) one thermoelectric element each ( 130 ) and at each of the thermoelectric elements ( 130 ) an outer fluid guide element ( 140 ) is arranged. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that the inner fluid guiding element ( 110 ) consists of a block of material, in particular a metal block, in which openings or bores as fluid channels ( 120 ) and / or wherein at least one outer fluid guiding element ( 110 ) consists of a block of material, in particular a metal block, in which openings or bores as fluid channels ( 120 ) are introduced. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that the inner fluid guiding element ( 110 ) has a cubic shape. Thermoelectric unit ( 100 ) according to one of the preceding claims 1 to 4, characterized in that the inner fluid guiding element ( 110 ) in cross-section normal to a fluid flow direction through the fluid channels ( 120 ) has a hexagonal or octagonal shape. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that in the inner fluid guiding element ( 110 ) the fluid channels ( 120 ) are arranged in a matrix shape in a plurality of rows and columns. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that the fluid channels ( 120 ) in at least one of the outer fluid guiding elements ( 140 ), in particular in all outer fluid guiding elements ( 140 ), are arranged in a single row and a plurality of columns. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that the fluid channels ( 120 ) of the inner fluid guiding element ( 110 ) and / or at least one of the outer fluid guiding elements ( 140 ) have a round and / or circular cross section and / or a cross section with recesses, in particular a star-shaped cross section. Thermoelectric unit ( 100 ) according to one of the preceding claims, characterized in that the thermoelectric elements ( 130 ) Are Peltier elements. Thermoelectric system comprising: - a first thermoelectric unit ( 100 ) according to one of the preceding claims; and a second thermoelectric unit ( 100 ) according to one of the preceding claims, wherein the fluid channels ( 120 ) of the inner fluid guiding element ( 110 ) the first thermoelectric Unit ( 100 ) with the fluid channels ( 120 ) of the inner fluid guiding element ( 110 ) of the second thermoelectric unit ( 100 ) and the fluid channels ( 120 ) at least one outer fluid guide element of the first thermoelectric unit ( 100 ) with the fluid channels ( 120 ) at least one of the outer fluid guiding elements ( 140 ) of the second thermoelectric unit ( 100 ), in particular wherein an adhesive material and / or a sealing ring for connecting the fluid channels ( 120 ) of the inner fluid guiding element ( 110 ) the first thermoelectric unit ( 100 ) with the fluid channels ( 120 ) of the inner fluid guiding element ( 110 ) of the second thermoelectric unit ( 100 ) and / or for connecting the fluid channels ( 120 ) at least one outer fluid guide element ( 140 ) the first thermoelectric unit ( 100 ) with the fluid channels ( 120 ) at least one of the outer fluid guiding elements ( 140 ) of the second thermoelectric unit ( 100 ).

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