Microstructured apparatus for heating a fluid
In a microstructure apparatus for heating a fluid with an inner body received in an outer tube, circumferential micro-passages are formed into the inner surface of the outer tube or the outer surface of the inner body so as to form a flow passage which is provided with inlet and outlet flow structures and heating means are incorporated into the inner body for heating the fluid conducted through the micro-structured flow passages.
This is a Continuation-In-Part Application of International Application PCT/EP03/007954 filed Jul. 22, 2003 and claiming the priority of German application 102 34 043.9 filed Jul. 26, 2002.
BACKGROUND OF THE INVENTIONThe invention relates to a microstructure apparatus for heating a fluid, comprising an inner tube surrounded by an outer tube and a microstructure formed at the interface between the inner and the outer tubes.
Microstructure apparatus for heating fluids are used particularly for a position-independent condensation-free evaporation of liquids and for continuous flow heating particularly of gases. Preferred areas of utilization are chemical or pharmaceutical processes and generally the chemical engineering field.
It is generally known to heat fluids by way of electric heating elements. This has the advantage that the heat transfer can be controlled rapidly and in a simple manner by controlling the electric power input. In this connection, micro-structure apparatus have the advantage that, because of the principally smaller dimensions, the heat transfer paths are short and a large specific heat transfer surface can be provided such that the volume-based heat transfer can be relatively high.
DE 199 17 521 A1 discloses such a microstructure apparatus including direct and indirect electrical resistance heaters for heating fluids. The microstructure apparatus comprises layers including microwave channels for the passage of a fluid to be heated and layers including electrical heaters. In comparison with a conventional heat exchanger which is not microstructured, a volume-specific increase of the heat transfer of at least the factor 100 is mentioned. The proposed inner structured apparatus however requires several heating elements with dimensions in the micro-range. For designing the microstructure apparatus for larger fluid flows a number of such heating elements are required and that number increases with the flow volume for added capacity. This is necessary particularly if the volume-specific heat transfer capacity of the microstructure apparatus must not be reduced.
It is therefore the object of the present invention to provide a microstructure apparatus for heating fluids which has heating elements that are simple in their design and which, furthermore, does not have the disadvantages incurred with the design of such apparatus for larger fluid flow volumes.
SUMMARY OF THE INVENTIONIn a microstructure apparatus for heating a fluid with an inner body received in an outer tube, circumferential micro-passages are formed into the inner surface of the outer tube or the outer surface of the inner body so as to form flow passages which is provided with inlet and outlet structures and healing means are incorporated into the inner body for heating the fluid conducted through the microstructure flow passages.
It is particularly important that a relatively large or macroscopic heating element is used which has operational advantages in comparison with several micro-heating elements, such as comparatively simple handling and low cost and also use advantages, in combination with a microstructure with its advantage of high efficiency in the transfer of heat to a fluid as pointed out earlier.
The materials of which the microstucture apparatus is manufactured are determined mainly by the application for the apparatus. Basically any materials such as ceramics or other inorganic, non-metallic materials, metals, plastics or combinations or compounds of these materials are suitable.
Below the invention will be described in greater detail on the basis of some embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The first embodiment, as shown in
The microstructure is essentially encased between the inner and the outer tubes wherein, ideally, the inner and outer tubes are in sealing engagement at the contact areas.
The microstructure 5 is in the embodiment shown in
The inner tube 1, which is shown in all figures to be longer than the outer tube 2 extends at both ends from the outer tube 2, although this not necessary. This is also true for a body with a cylindrical outer surface which may be used in place of an inner tube 1 as mentioned earlier. The inner tube or such inner body is in all the embodiments directly or indirectly part of a heating structure. As a direct part of a heating structure, the tube or the body is an integral component of a heating device for example in the form of a resistance heating element. As an indirect part, the tube or the body is for example a heat conductor which conducts heat from a separate heater to the fluid to be heated. These may be separate heaters arranged within the inner tube or adaptively connected to the body. As heaters, electric resistance heating elements are considered to be particularly suitable. Alternatively, a heating medium may be conducted through the inner tube for heating the inner tube 1.
In a third embodiment as shown in
Basically, also other embodiments are possible wherein both connections are provided by open ends of the thread-like microstructure passages. Such an arrangement could be miniaturized in a particularly advantageous manner since separate connectors or sealed connections would not be needed.
Such an embodiment could furthermore be used as continuous flow heater installed between two separate fluid volumes. Since, with such an arrangement, no fluid losses could occur by leakages, sealed connections between the inner and outer tubes would also not be necessary. Further uses for embodiments with the thread-like passages open at least at one end of the outer tube would be for example the atomizing of a liquid to a spray or an aerosol or in the gasification or vaporization of a liquid wherein the particular advantage of the microstructure apparatus resides in its particularly sensitive and accurately adjustable flow control capability.
Another embodiment of the microstructure apparatus is shown in
The microstructure passages 5 or the microstructure flow chain may be accessed at any location by additional connections. In this way, fluid amounts with an intermediate temperature can be withdrawn or introduced. Applications for such arrangements are present particularly in chemical engineering, wherein certain reactants or catalysts for chemical reactions must be introduced within a narrow temperature range or small fluid amounts with a certain temperature or a temperature profile must be withdrawn for example for an analysis.
Basically, the microstructure apparatus may be conceived as a chemical micro-reactor. Depending on the application, one or more reaction chambers, that is, one or more areas with increased volume of the passages may be provided in the microstructure or microstructure chain. Further, the manufacture of the whole microstructure apparatus or parts thereof, for example the inner, the intermediate or the outer tube of a catalytic material or a coating of the microstructure 5 at the contact areas with the fluid is possible. A further increase in the volume-specific heat transfer capability can be achieved by an increase in the volume-specific heat transfer area in the microstructure 5, for example, by a porous coating or by roughening of the heat transfer surface areas. The porous coating may also consist of a catalyst or the roughened heat transfer area may consist of a catalyst or be coated by a catalyst. In addition, to avoid corrosion and cavitation, the heat transfer surfaces may be provided with a protection layer consisting for example of a chemically resistant plastic or metallic material or with a wear layer of a chemically or physically deposited metal, hard material or ceramic material.
Claims
1. A microstructure apparatus for heating a fluid, comprising an inner body (1) having an outer surface and including a heating structure,
- an outer tube (2) concentrically surrounding said inner body (1) and having an inner surface in sealing contact with said inner body (1),
- a microstructure formed in one of the inner surface of the outer tube (2) and the outer surface of the inner body (1) so as to form a fluid flow passage (5) between the inner body (1) and the outer tube (2), and
- connectors in communication with said fluid flow passage (5) for conducting a fluid to and from said fluid flow passage (5).
2. A microstructure apparatus according to claim 1, wherein said microstructure is in the form of a groove (5) extending thread-like around the inner body (1).
3. A microstructure apparatus according to claim 1, wherein said microstructure is a groove (5) formed like an internal thread into the inner surface of the outer tube (2).
4. A microstructure apparatus according to claim 1, whereby sealing rings (3) are disposed between the inner body (1) and the outer tube (2) at least one end of the outer tube.
5. A microstructure apparatus according to claim 1, wherein at least a fluid admission connector and a fluid discharge connector are provided at opposite ends of the outer tube (2) and a screw-like flow passage forms the only communications path between the fluid admission and discharge connectors.
6. A microstructure apparatus according to claim 1, wherein at least one intermediate tube (7) is disposed between the inner body (1) and the outer tube (2) and each intermediate tube (7) is provided with a microstructure forming a screw thread-like passage between the intermediate tube (7) and a radially adjacent tube or body, the passages being in communication with one another by communication openings (8) extending through said intermediate tubes (7) so as to join the flow passages in a series flow arrangement.
7. A microstructure apparatus according to claim 1, wherein the connectors (4) are in communication with longitudinal fluid inlet and outlet passages (6) extending over the length of the outer tube (2) at radially opposite sides and providing for communication between the circumferential fluid flow passages (5″) and providing for parallel flow arrangement for the circumferential passages between the inlet and outlet passages (6).
8. A microstructure apparatus according to claim 1, wherein at least one enlarged cross-sectional area is provided in said fluid flow passage forming a reaction chamber between the inlet and outlet connectors (4).
9. A microstructure apparatus according to claim 1, wherein the channel walls formed by the microstructure flow passages (5) have a rough surface.
10. A microstructure apparatus according to claim 9, wherein the channel walls are provided with a porous coating.
11. A microstructure apparatus according to claim 1, wherein the channels formed by said microstructure are provided with a wear-resistant coating.
12. A microstructure apparatus according to claim 1, wherein the channels formed by said microstructure are provided with a corrosion resistant coating.
13. A microstructure apparatus according to claim 1, wherein at least parts of the microstructure apparatus consist of a catalytically active material.
14. A microstructure apparatus according to claim 1, wherein the channels formed by said microstructures 5 are coated with a catalytically active material.
15. A microstructure apparatus according to claim 1, wherein the heating structure is an electric resistance heating element.
16. A microstructure apparatus according to claim 15, wherein said inner body (1) is an inner tube and the heating element is arranged in the inner tube.
17. A microstructure apparatus according to claim 15, wherein the heating element is an integral component of the inner body (1).
18. A microstructure apparatus according to claim 1, wherein the inner body (1) is in the form of a resistance heating element.
Type: Application
Filed: Nov 12, 2004
Publication Date: Mar 24, 2005
Inventors: Klaus Schubert (Karlsruhe), Jurgen Brandner (Heidelberg)
Application Number: 10/987,684