DE102017000645A1 - Heat exchanger with porous Wärmeleitabschnitt - Google Patents

Abstract

The invention relates to a usable as a reactor and in particular as a microreactor heat exchanger with at least two fluidly separated by at least one wall Fluidleitbereichen, wherein at least one side of the wall at least one integrally manufactured porous Wärmeleitabschnitt is arranged. The invention is further directed to a method of making a corresponding heat exchanger.

Description

The invention relates to a usable as a reactor and in particular as a microreactor heat exchanger with at least two fluidly separated by at least one wall Fluidleitbereichen, wherein at least one side of the wall at least one integrally manufactured porous Wärmeleitabschnitt is arranged.

When designing heat exchangers, a significant factor to consider is the different thermal conductivities of solids and fluids, which can differ by up to five orders of magnitude. Furthermore, the transfer of heat in a heat exchanger from a first fluid phase 1 to a second fluid phase 2 first always makes a heat transfer to a solid phase necessary. In the following, the solid phase corresponds to the wall of the heat exchanger. This heat transfer to the wall takes place only on the surface of the solid phase or wall, which separates the hot from the cold heat transfer fluid.

The transmittable heat flow of a heat exchanger apparatus or heat exchanger is thus proportional to its inner surface, which is effectively available for the exchange of heat. By enlarging this inner surface thus a higher heat output can be transmitted.

It is known that a large number of porous / spongy materials have high internal surfaces. Known methods of fabricating unstructured porous metallic electrodes by selective laser melting (SLM) can be used to produce heat exchangers with very high internal surfaces with the heat exchange advantages already mentioned. So far, similar surface-to-volume ratios have only been achieved by micro heat exchangers, which are made of very complex and often multi-part constructions. The heat exchangers manufactured in the SLM process can be manufactured in just one process step with previously unattainable geometrical design possibilities.

Through the use of catalytically active production materials or subsequent coating process, the use of these heat exchangers is also very suitable as reactors or microreactors for the use or for performing highly heat-colored reactions, since here the large inner surface both on the heat transfer and the Reaction has a positive effect.

Against this background, it is an object of the invention to provide a usable as a reactor and in particular as a microreactor heat exchanger with an enlarged inner surface for more effective exchange of heat.

This object is achieved by a heat exchanger with the features of claim 1. Advantageous embodiments are the subject of the dependent claims. Accordingly, a heat exchanger which can be used in particular as a microreactor is provided with at least two fluid guide sections which are fluidically separated by at least one wall. At least one side of the wall is at least one integrally manufactured, porous, that is pores comprehensive, Wärmeleitabschnitt arranged.

The term porosity of the heat-conducting section is to be interpreted broadly and means that pores are provided in the structure of the heat-conducting section. By a pore is here meant the geometry of a non-closed cavity, which is bounded at least in part or predominantly by non-planar and in particular complex curved and / or angled and / or concave wall sections. Pores occurring according to the invention thus differ substantially from embodiments of the heat-conducting sections known from the prior art. In contrast to the pores provided according to the invention, the known heat-conducting sections have simple planar and / or simply curved geometries which can be produced by means of conventional production methods, by means of which pores can not be represented in the sense of the invention. The conventional production methods are, for example, bar pressing methods. The pores provided according to the invention can each communicate with one pore or with a plurality of adjacent pores, so that the pores do not constitute closed cavities. It is also a heterogeneous configuration of the pores conceivable in which a part of the pores communicates with only one adjacent pore and another part of the pores communicates with more than one adjacent pore. The heat transfer of the Wärmeleitabschnitts takes place in any case over the wall sections surrounding the pores. Due to the configuration of the heat-conducting section as a porous component, the inner surface of the heat-conducting section can be enlarged and thus a higher heat output can be transmitted. In the present case may be mentioned by Fluidleitabschnitten or Fluidleitbereichen or by Wärmeleitabschnitten or Wärmeleitbereichen, the terms may each have the same meaning.

In a preferred embodiment of the invention is conceivable that on both sides of the Wall is arranged in one piece manufactured in particular porous Wärmeleitabschnitt. If a cold fluid is present in a first fluid-conducting region while a hot fluid is present in the second fluid-conducting region separated from the first fluid region by the wall, heat transfer can take place via the corresponding heat-conducting sections in both fluid-conducting regions. The maximum transferable heat output is thereby further increased.

In a further preferred embodiment, it may further be provided that the wall and at least one of the heat-conducting sections are manufactured in one piece or that the wall, at least one of the heat-conducting sections and a housing section of the heat exchanger are manufactured in one piece. The one-piece production of said components, the entire manufacturing cost of the heat exchanger can be further reduced and thus the corresponding manufacturing costs can be further reduced. In the present case, the term "housing section" may refer to a part or the entire housing of the heat transfer, wherein in particular fluid connections and / or mechanical connections or further components in and / or on the housing may also be manufactured in one piece with the above-mentioned components, in particular by means of selective laser melting ,

In a particularly preferred embodiment, the basic structure of the integrally manufactured component or components can be manufactured in a single production step, wherein the production step is an additive production step, in particular selective laser melting.

In the present context, the term "basic structure" refers to the structure which can be produced in the individual production step, wherein changes or additions to the basic structure carried out in subsequent production steps, such as, for example, in process steps for coating or finishing the basic structure, are not included. The individual production step for producing the basic structure thus comprises the additive production or additive production of the geometry or of the basic body of the corresponding components or of the corresponding components from the material used in the additive production or the materials used therein. The term component refers in the present case to the abovementioned constituents of the heat exchanger, such as the at least one heat-conducting section, the wall, the at least one fluid-conducting region, the housing or parts of the housing, mechanical connections, fluid connections and / or further components required in particular for the operation of the heat exchanger.

By using an additive manufacturing step, it is possible to produce even complex pore geometries particularly easily and thus to provide a cost-optimized geometry of the pores and the further microstructure of the heat exchanger that is better adapted to the flow conditions and / or the temperature conditions in the heat exchanger.

In a further preferred embodiment, it may further be provided that at least the heat-conducting section of the heat exchanger is coated. It is thus possible to subject the heat-conducting section and optionally further components of the heat transfer after the one-piece production or during the one-piece production to a coating process or step in which increased corrosion protection and / or catalytic properties of the coating can be utilized to form the heat-conducting section by appropriate application of the coating to modify.

In a further preferred embodiment, it is further conceivable that the pores positioned closer to the wall communicate with the pores further apart from the wall, wherein in particular all adjacent or a part of the adjacent pores communicate with one another. Corresponding communication channels or connections between the pores have, on the one hand, the function of enabling a flow of fluid between the pores so as to ensure or improve the functioning of the heat exchanger and, on the other hand, the non-molten or not to be disposed of during the production process of the heat exchanger to remove used residues of the material powder used or to remove them from the structure of the heat-conducting section.

In a further preferred embodiment, it is conceivable that at least a portion of the pores furthest from the wall communicates directly with the associated fluid guide section. This may be a configuration in which a fluid-conducting section spaced from the respective heat-conducting section is arranged on a side of the heat-conducting section opposite the wall, wherein the heat-conducting section and the fluid-conducting section are at least partially not penetrated or spatially separated from one another. A fluid guide section and a heat conduction section are then associated with each other when the fluid in the fluid guide section contacts the heat conduction section. By direct communication is meant in the present case that no further pores are provided between the pores spaced apart from the wall and the fluid-conducting section, but, for example, passages from the pores to the fluid-conducting section.

In a further preferred embodiment, it is conceivable for the fluid-conducting section and the heat-conducting section to penetrate one another at least partially or completely, wherein the fluid-conducting section is arranged at least partially within the pores of the heat-conducting section.

By the at least partial arrangement of the Fluidleitabschnitts within the pores of the Wärmeleitabschnitts the largest possible flowed through or flowed surface of the Wärmeleitabschnitts can be ensured and thereby the most effective heat transfer between the Fluidleitabschnitten be ensured. In particular, it is conceivable for the fluid-conducting section to be arranged completely within the pores of the heat-conducting section.

Furthermore, an embodiment is conceivable in which the size and / or shape of the pores and / or the porosity depend at least partially on the temperature gradient to be achieved and / or on the fluid flow to be achieved and / or on the heat flow to be achieved within the heat exchanger, In particular, the pores and / or the porosity in areas with high heat transfer or high temperature difference between the Fluidleitabschnitten is smaller or larger and / or wherein the pores and / or porosity in areas with low heat transfer or low temperature difference between the Fluidleitabschnitten larger or smaller are / are in other areas, and / or wherein the pores are configured to generate a constant or a defined changing flow resistance over all or part of the Fluidleitabschnittes. The term heat transfer can in this case mean the heat transfer between a fluid and the respective heat-conducting section and / or the heat transfer between a fluid-conducting section and another fluid-conducting section via the intermediate wall and at least one heat-conducting section. The corresponding design of the pores or the porosity makes it possible to better adapt the respective section of the heat exchanger to the heat and / or fluid transfers occurring therein. When using the heat transfer as a reactor, for example, the changing during a reaction fluid behavior can be taken into account, whereby the reaction sequence can be improved and / or the reactor can be made smaller and therefore less expensive. The precise pore geometry can thus be defined as part of an optimization task, whereby all relevant parameters occurring at the heat exchanger, such as the fluid temperatures, the heat transfer coefficients, the fluid viscosities, the flow resistances or the pressure losses occurring at the pores, can be taken into account. Accordingly, a heat exchanger geometry with the smallest possible dimension, the highest possible heat transfer, the lowest possible pressure loss and / or other properties depending on the respective parameters can be determined.

The invention is further directed to a reactor, in particular microreactor comprising features of the heat exchanger according to one of claims 1 to 7.

The invention is also directed to a method of manufacturing a heat exchanger according to any one of claims 1 to 7, wherein at least one heat conducting section is produced by selective laser melting. Particularly preferably, in this case the at least one heat-conducting section and at least one further component of the heat exchanger can be manufactured in one piece.

• 1: schematische Darstellung des Wärmeübergangs zweier unterschiedlich temperierter fluider Phasen an einer Feststoffwand; und
• 2: ein Ausführungsbeispiel eines erfindungsgemäßen Wärmeübertragers.

Further details and advantages of the invention are explained with reference to the embodiments shown by way of example in the figures. Showing:

• 1 : schematic representation of the heat transfer of two differently tempered fluid phases on a solid wall; and
• 2 : An embodiment of a heat exchanger according to the invention.

1 shows the heat transfer and the temperature distribution of two different temperature-controlled fluid phases, by means of a solid wall or a wall 2 are fluidly separated from each other. In the left area of the 1 is a first Fluidleitbereich 3 shown with a first fluid therein. In a second Fluidleitbereich 4 a corresponding second fluid is provided. In this case, the second fluid has a lower temperature than the first fluid in accordance with the temperature curve highlighted in bold. In 1 The higher the corresponding temperature, the higher the temperature curve is. Left and right of the wall 3 are shown by dashed line thermal boundary layers in which the fluid temperature of the surface temperature of the respective side of the wall 3 approaches. Inside the wall 3 a linear temperature profile is shown, which may vary depending on the temperature gradient between the first and the second fluid different steep and depending on the design of the wall may not be linear.

2 shows a heat exchanger according to the invention 1 in sectional view and with two Fluidleitbereichen 3 . 4 which are separated from each other by means of a wall 2 are fluidically isolated. In the embodiment of 2 are on both sides of the wall 3 Wärmeleitabschnitte 31 . 41 arranged, the porous may be formed or a plurality of pores 10 may include

For a better overview because of the reference numerals 31 . 41 only part of the structure of the Wärmeleitabschnitte 31 . 41 and with the reference numeral 10 only a part of the pores 10 designated. The term porosity is to be construed broadly and can include any free geometries or surface courses in which plane and / or non-planar sections of the heat-conducting section 31 . 41 Form pore walls, wherein a fluid flow over the pores thus formed 10 and a heat transfer across the pores 10 surrounding material is possible. As 2 it can be seen, the Wärmeleitabschnitte 31 . 41 from the pores 10 consist of surrounding or forming material and be made in each case or together in one piece. In contrast to known Wärmeleitabschnitten form Wärmeleitabschnitte invention 31 . 41 pore 10 from whose walls may consist partially or predominantly of concave wall sections, and / or wherein the individual pores 10 communicate with each other.

The wall 3 and both heat conducting sections 31 . 41 are in the embodiment of 2 integral with the housing 5 of the heat exchanger 1 manufactured. The method used for the production of the components mentioned can be any additive or generative production method with which metallic materials can be processed. In particular, the method may be selective laser melting, which includes the porous design and the integral fabrication of more than one component of the heat exchanger 1 particularly easy.

The surfaces of the Wärmeleitabschnitte 31 . 41 or the corresponding pore walls and optionally further surfaces of the heat exchanger 1 can be coated according to the additive production of the basic structure of the corresponding components by a coating process accordingly. The coating applied in this way can, for example, bring about corrosion protection of the correspondingly coated components and / or provision or improvement of catalytic properties of the corresponding surfaces. Especially when using the heat exchanger 1 As a reactor, by providing a catalytically active surface, a desired reactor function can be achieved. Due to the present invention particularly large surface of the Wärmeleitabschnitte 31 . 41 It is possible to form corresponding reactors particularly small than microreactors. This results in corresponding cost advantages in the production and use of the microreactors according to the invention. These can be produced with less material and require less space. In particular, when using expensive catalyst materials in the coating of the reactor, this results in a cost advantage.

As 2 It can be seen, the closer to the wall 2 positioned pores communicate with the more distant from the wall pores, in particular, the respective adjacent pores can communicate with each other. At the farthest from the wall pores may have their own Fluidleitbereich 3 . 4 connect or it may be the Fluidleitbereich 3 . 4 be within the pores or arranged. In this case, the fluid guide areas penetrate correspondingly 3 . 4 and the Wärmeleitabschnitte 31 . 41 ,

As in 1 so can also in 2 the left-hand portion is flowed through by a fluid having an elevated temperature. According to the arrow, the first Fluidleitbereich 3 flows through from the bottom to the top of the first, hot or hot fluid, wherein the first fluid is cooled during the passage of the heat exchanger. Accordingly, it leaves the first Fluidleitbereich 3 with a lower temperature than it flows into this. Thus, the first fluid has a common temperature gradient. The heat-conducting sections 31 . 41 may be formed as a function of the temperature gradient and / or the fluid flow of the respective fluids, wherein in particular the structure of the pores may be formed as a function of the temperature gradient and / or the fluid flow.

As in 2 can be seen, the pores can be designed so that they have in a region in which the first fluid has its highest temperature, their smallest dimensions or volume, while the pores in areas of the fluid in which this is its lowest temperature may have their largest volumes. Considering the individual regions of the porous structure of the Wärmeleitabschnitte 31 . 41 , it is found that in areas in which the fluid has a high temperature, the porosity and / or the pore size may be reduced, whereby in turn more material of the Wärmeleitabschnitts 31 . 41 is available for the heat transfer, while in areas with lower fluid temperature of the first fluid larger pores and / or greater porosity may occur, although less material for heat transfer within the Wärmeleitabschnitts 31 . 41 but a larger surface for the heat transfer from the fluid to the Wärmeleitabschnitt 31 . 41 is available. It is also conceivable to take into account the fluid flow and, in particular, changes occurring in it in the configuration of the pores, so that in areas with, for example, increased fluid flow due to the reaction, the pores are designed for a lower fluid resistance.

The embodiment of the second Wärmeleitabschnitts 41 which in the embodiment of the 2 is associated with the colder, second fluid can, accordingly, taking into account the temperature gradient of the colder second fluid and taking into account the from the first Wärmeleitabschnitt 31 and the wall 2 recorded or transmitted heat output can be formed.

In 2 only a simple example of heat transfer is shown. However, all common geometries of heat exchangers are conceivable in the practice of the invention.

3 shows a heat exchanger according to the invention 1 in which an undefined porous interior of the heat exchanger 1 is present. Although in the 2 structured pores 10 Unstructured pores can also be shown 10 be provided as they are in 3 are indicated. The concept of unstructured pores 10 denotes a pore geometry, in which the configuration and / or positioning of the individual pores 10 without structure or only with a structure recognizable on a macro level. It is conceivable, for example, that the pores 10 having area in two or more subareas 3a . 3b . 4a . 4b subdividable, one of which has, for example, pores 10 with an average larger or smaller pore wall surface and / or with average larger or smaller pore spacings, than the other region or as the other regions. The appearance of the pores 10 in the 2 can therefore be understood as a merely schematic representation.

According to 3 can be a first subsection 3a a first Fluidleitunterabschnitt 3 'within the pores of a first Wärmeleitunterabschnitts not shown 31 ' while a second sub-area 3b a second fluid guide subsection 3 ' within the pores, also not shown 10 a second Wärmeleitunterabschnitts 31 " can have. The pores may in particular be averaged or average in terms of their geometry and / or their distances from each other as described above between the subsections mentioned differ. The same applies to the third and fourth subareas 4a . 4b , The individual subareas 3a . 3b . 4a . 4b can in this case depending on the desired properties of the heat exchanger 1 be configured and / or positioned.

Claims (10)

Heat exchanger (1), with at least two by at least one wall (2) fluidly separated Fluidleitabschnitt (3, 4), characterized in that arranged on at least one side of the wall (2) at least one integrally manufactured, porous heat-conducting portion (31, 41) is. Heat exchanger (1) after Claim 1 , characterized in that on both sides of the wall (2) an integrally manufactured heat conducting portion (31, 41) is arranged. Heat exchanger (1) after Claim 1 or 2 , characterized in that the wall (2) and at least one heat-conducting portion (31, 41) are made in one piece or that the wall (2), at least one heat-conducting portion (31, 41) and a housing portion (5) of the heat exchanger (1) in one piece are made. Heat exchanger (1) after Claim 1 . 2 or 3 , characterized in that the basic structure of the integrally manufactured component or components is manufactured in a single manufacturing step, wherein the manufacturing step is an additive manufacturing step, in particular selective laser melting. Heat exchanger (1) according to one of the preceding claims, characterized in that at least the heat-conducting portion (31, 41) of the heat transfer (1) is coated, and / or that the closer to the wall (2) positioned pores (10) with the further from the wall (2) spaced pores (10) communicate, in particular all adjacent or a part of the adjacent pores (10) communicate with each other. Heat exchanger (1) according to one of the preceding claims, characterized in that at least a part of the farthest from the wall (2) spaced pores (10) with the associated Fluidleitabschnitt (3, 4) communicates directly, and / or that the Fluidleitabschnitt ( 3, 4) and the heat-conducting section (31, 41) penetrate each other at least partially or completely, the fluid-conducting section (3, 4) being arranged at least partially within the pores (10) of the heat-conducting section (31, 41). Heat exchanger (1) according to one of the preceding claims, characterized in that the size and / or shape of the pores (10) and / or the porosity at least partially of the temperature gradient to be achieved and / or of the fluid flow to be achieved and / or of the depend to be reached heat flow within the heat exchanger (1), in particular the Pores (10) and / or the porosity in areas with high heat transfer or high temperature difference between the Fluidleitabschnitten (3, 4) are smaller or larger / and / or wherein the pores (10) and / or porosity in low heat transfer areas or low temperature difference between the Fluidleitabschnitten (3, 4) are larger or smaller than in other areas, and / or wherein the pores (10) are adapted to a constant or defined changing flow resistance over the entire or a part of the Fluidleitabschnittes (3, 4). Reactor, in particular microreactor, characterized in that it comprises the features of the heat exchanger according to at least one of claims 1 to 7. Method for producing a heat exchanger (1) according to one of Claims 1 to 7 , characterized in that at least one heat-conducting section (31, 41) is produced by selective laser melting. Method according to Claim 9 , characterized in that the at least one heat-conducting portion (31, 41) and at least one further component of the heat exchanger (1) are made in one piece.

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