Propulsion element including a catalyzing reactor

Abstract

A propulsion element including a catalyzing reactor is disclosed. The catalyzing reactor comprises a reactor entrance and a reactor exit and an internal structure arranged for flowing a reacting medium through the reactor from the reactor entrance to the reactor exit. The reactor structure comprising at least one thin walled reactor channel arranged between the entrance and the exit of the reactor. The channel having a channel wall that includes a catalyst and that defines a flow path, in which channel in use, a catalyzed exothermic reaction takes place in the medium as it flows along the flow path. The at least one channel is looped to have a portion of its flow path that is downstream with respect to the reactor entrance in heat exchanging contact with a portion of a flow path that is that is more upstream with respect to the reactor entrance, so as to transfer heat between a downstream portion of the reacting medium to an upstream portion thereof.

Claims

1. A propulsion element including a catalyzing reactor, the catalyzing reactor having a reactor entrance, a reactor exit, and an internal structure configured for flowing a reacting medium from the reactor entrance to the reactor exit, the internal structure comprising at least one reactor channel having a channel wall that includes a catalyst for catalyzing a reaction of the reacting medium, wherein the reactor channel defines a flow path between the reactor entrance and the reactor exit, and wherein the reactor channel is looped such that a first portion of the flow path that is relatively more downstream with respect to the reactor entrance is proximate, and in heat exchanging contact with, a second portion of the flow path that is relatively more upstream with respect to the reactor entrance, the reactor channel being configured for transferring heat between the reacting medium present in the first portion of the flow path and the reacting medium present in the second portion of the flow path.

2. The propulsion element of claim 1, wherein a ratio of a thickness of the channel wall to a minimum inner diameter of the reactor channel is less than 0.05.

3. The propulsion element of claim 2, wherein the ratio of the thickness of the channel wall to the minimum inner diameter of the reactor channel is between 0.01 and 0.05.

4. The propulsion element of claim 2, wherein the ratio of the thickness of the channel wall to the minimum inner diameter of the reactor channel is less than 0.01.

5. The propulsion element of claim 1, wherein a ratio of a thickness of the channel wall to a length of the channel is less than 0.001.

6. The propulsion element of claim 5, wherein the ratio of the thickness of the channel wall to the length of the channel is less than 0.0001.

7. The propulsion element of claim 1, wherein the channel wall is shared between the first portion of the flow path that is relatively more downstream with respect to the reactor entrance and the second portion of the flow path that is relatively more upstream with respect to the reactor entrance.

8. The propulsion element of claim 1, wherein the internal structure comprises a bundle of reactor channels, wherein each reactor channel of the bundle defines a respective flow path between the reactor entrance and the reactor exit.

9. The propulsion element of claim 8, wherein the respective flow paths of the reactor channels are not in fluid communication with each other.

10. The propulsion element of claim 8, wherein each respective flow path has a respective, relatively more downstream portion and a respective, relatively more upstream portion, wherein each respective, relatively more downstream portion of the flow path shares a common wall with (i) the respective, relatively more upstream portion of the flow path, (ii) an adjacent reactor channel of the bundle of reactor channels, or (iii) both (i) and (ii).

11. The propulsion element of claim 10, wherein each respective, relatively more downstream portion of the flow path shares a common wall with the respective, relatively more upstream portion of the flow path.

12. The propulsion element of claim 1, wherein the reactor channel has at least one reversed section for looping the reactor channel back onto itself and/or at least one other reactor channel of a bundle of reactor channels of the internal structure.

13. The propulsion element of claim 12, wherein the at least one reversed section is part of a U-shaped form, an N-shaped form, or an S-shaped form.

14. The propulsion element of claim 1, wherein the reactor channel has, at an entrance end, an entrance cross section in a plane of the reactor entrance and has, at an exit end, an exit cross section in a plane of the reactor exit, said plane of the reactor exit being spaced apart from said plane of the reactor entrance.

15. The propulsion element of claim 1, wherein the reactor channel has a varying cross section along the flow path.

16. The propulsion element of claim 1, wherein the channel wall is made from a heat conducting catalytic material.

17. The propulsion element of claim 1, wherein the propulsion element is part of a thruster and/or an igniter and is configured to decompose the reacting medium into reaction products including an accelerated superheated gas to provide thrust.

18. The propulsion element of claim 17, wherein the thruster and/or the igniter is a component of a spacecraft.

19. The propulsion element of claim 1, wherein the catalyzing reactor is formed by adding successive layers of material to each other.

20. The propulsion element of claim 1, wherein the reacting medium is a liquid or a gaseous propellant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be further elucidated on the basis of an exemplary embodiment which is represented in a drawing. In the drawing:

(2) FIG. 1 shows a catalytic reactor;

(3) FIG. 2 shows a cutaway of one of the channels of the catalytic reactor of FIG. 1;

(4) FIG. 3 shows a cross section of the channel of the catalytic reactor of FIG. 1;

(5) FIG. 4 shows a cross section of the channel according to a second embodiment of the catalytic reactor;

(6) FIG. 5 shows a cross section of the channel according to an embodiment of the catalytic reactor.

(7) It is noted that the figures are merely schematic representations of a preferred embodiment of the invention, which is given here by way of non-limiting exemplary embodiment. In the description, the same or similar part and elements have the same or similar reference signs.

DETAILED DESCRIPTION

(8) In FIG. 1 a catalyzing reactor 1 is shown. The reactor 1 is in this exemplary embodiment shown as a cylinder. However, other shapes are also possible such as a triangle, ellipsoid or rectangular. The reactor 1 may have a reactor entrance 2 and a reactor exit 3 and an internal structure 4 wherein a reacting medium can flow through the reactor 1 from the reactor entrance 2 to the reactor exit 3. The reactor structure 4 may comprise at least one reactor channel 5 with a relative thin channel wall 6 in comparison with the diameter, minimum width and/or minimum length of the reactor channel 5. Preferably, as shown in FIG. 1, the internal structure 4 may, for example, be designed as a honeycomb structure with a bundle of thin-walled heat conducting channels 5. The channels 5 can be arranged between the entrance 2 and the exit 3 of the reactor 1. The channels 5 may have a channel wall 6 that is made from a catalytic material or a non-catalytic support material and then coated with a catalytic material. In FIG. 2 a cutaway of one of the channel 5 of the reactor 1 is shown. The channel 5 may have a thin channel wall 6 and an inlet 7 and outlet 8 in which a medium can flow. When in use, the medium may flow through these plurality of channels 5 and the medium may react via the catalytic material on the inside of the channels 5, in particular, via the catalyst arranged on the channel wall 6 and thus a catalyzed exothermal reaction may take place inside the channels 5 as the medium flows along the flow path F from the entrance 2 to the exit 3 of the reactor 1. Due to the exothermal reaction, heat may be released on the inside of the channel 5 along the flow path F where more heat may be released on a portion of the flow path that is more downstream with respect the reactor entrance 2.

(9) FIGS. 2-3 show that one or more channels 5 may be looped along its flow path F of the channel 5 for looping the channel 5 back and/or in other directions, for example, downwards, upwards and/or sideward. The channel 5 may be looped onto itself or the channel 5 may be looped onto adjacent channels. Furthermore, in FIG. 2 is shown that a looped channel 5 may be of such design that its channel sections together form a substantially tube-shaped structure, e.g. a hexagonal structure, having outer sides that are substantially parallel to each other. Hence, such looped channels 5 may be provided in a stacked configuration together with one or more correspondingly formed looped channels and/or with one or more substantially straight and/or non-looped channels having outer wall sides being substantially parallel to each other. The channel wall of the channel 5 facing adjacent channel (not shown) is substantially parallel to the adjacent channel. The two adjacent channels share a common wall, e.g. integrally forming the outer walls of said two adjacent channels, for instance when the channels are formed by means of a 3D-printing technique.

(10) Further, it is shown that the cross sectional surface of the channel 5 is decreasing continuously from the inlet 7 to the outlet 8, but it is noted that it is also possible that the cross sectional surface of the channel 5 is increasing continuously from the inlet 7 to the outlet 8.

(11) Preferably, the channel 5 may be looped at a portion of the flow path where there is more released heat, due to the exothermic reaction, as compared to a portion of the flow path where there is less released heat. More preferably, a more downstream portion 9 of the flow path F with respect the reactor entrance 2 may be looped such that the more downstream portion 9 with respect to the reactor entrance 2 is in direct heat transferring contact with the portion of the flow path that is more upstream 10 with respect to the reactor entrance 2. The released heat of the reacting medium in the more downstream portion 9 may then be fed to the more upstream portion 10 thereof.

(12) Additionally, the downstream portion 9 of the flow path F may be looped back such that the downstream portion 9 shares a common thin wall 6 with its more upstream portion 10 or with the channel wall 6 of other channels 5 of the bundle of channels, as shown in FIG. 4. Released heat in the more downstream portion 9 of the flow path may then be looped back such that this heat may be in heat exchanging contact with the more upstream portion 10 thereof via the thin-wall 6.

(13) In FIG. 3 is shown that in this exemplary embodiment, due to its looping, the flow path F of the medium may be divided in three sections I, II, and III. In this example, section I may be the upstream portion of the flow path F as compared to the more downstream portion 9 of the flow path F in section II. Further, section II may be the more upstream portion 10 of the flow path in comparison with the more downstream portion 9 of the flow path F in section III. Released heat in section III may be transferred to section II via the channel wall 6 and released heat in section II may be transferred to section I via its channel wall 6. By looping the more downstream portion 9 of the flow path F such that heat may be fed to the more upstream portion 10 of the flow path, the catalytic reactor may have an improved cold start performance in comparison with, for example, a catalytic reactor without a loop.

(14) The honeycomb structure 4 of the reactor 1 may comprise a bundle of channels, and the channel of the bundle of channels may share a common thin wall 6 with an adjacent channel of the bundle of channels and/or share a common thin wall 6 with itself. The channels 5 may each be looped but in FIG. 4 is shown that the channels 5 may also be looped alternately with adjacent channels 5.

(15) To have a loop in the channel 5, the channel 5 may have one or more reversed section 11 for looping the channel 5, and preferably for looping the channel 5 back onto itself and/or other channels. The reversed section 11 may for example be shaped as an U-shaped section but may also have a meandering flow path F. Further, the channel wall 6 may have a degree of porosity to improve the heat exchange between the downstream portion 9 of the flow path F of the channel 5 to the upstream portion 10 of the flow path F of the same channel 5 and/or adjacent channels 5. Specifically, the wall 6 between the channels 5 may be made thin such that they may become partially porous and the medium may pass the wall 6 in a balanced way, so heat transfer upstream may be optimized.

(16) As shown in FIG. 1 of this exemplary embodiment the entrance 2 and the exit 3 of the reactor 1 are in mutually spaced apart planes. Preferably, the entrance 2 of the reactor may be arranged at a plane of the reactor 1 where the medium enters the reactor 1 and the exit 3 of the reactor is arranged on an opposite plane of the reactor where the medium may leave the reactor. Preferably, the channel 5 may extend substantially along the longitudinal axis X of the reactor from the entrance 2 to the exit 3.

(17) Along the flow path F of the medium, the channel 5 may have varying cross section, such as a convergent and/or divergent section such that the flow velocity and the pressure within the channel can be controlled. Additionally, the channel may have a hexagonal, triangular, rectangular, ellipsoid or any polygonal cross section, which may vary in shape along the length of the channel 5. The channel may be e.g. divergent and/or convergent. For example, the cross sectional surface of the channel 5 may change substantially continuously along the flow path F, or at least along a part of its flow path.

(18) Further, a bundle of channels 5 may be stacked together to form an polygonal cross section e.g. hexagonal shaped cross section.

(19) As indicated with dashed lines in FIG. 4, by looping the channel 5 such that the flow may travel the length of the reactor e.g. three times, it may be possible that the channel diverge and/or converge without increasing the cross section of the bundle of channels. This way, more bundle of channels can be stacked into the cylinder shaped reactor, thus increasing the efficiency of the reactor.

(20) In FIG. 5 is shown that the channel 5 having the reversed section 11 has a continuously increasing cross sectional surface along its flow path F from the inlet 7 to the outlet 8. The channel wall 6 of the channel 5 having the reversed section 11, facing towards the adjacent channel shares a common channel wall 6 with the adjacent channel.

(21) When the medium is flowing through the channel 5, a heterogeneous catalytic reaction may occur between the medium flowing through the channel 5 and the catalyst arranged on the channel wall 6. The reactor 1 may be used as a thruster or an igniter with an improved cold start performance, and the medium flowing through the channel 5 is a fluid preferably a liquid medium such as hydrogen peroxide. The reactor 1 may then decompose a mass flow of hydrogen peroxide into water and superheated gaseous medium such as superheated oxygen gas. Alternatively or additionally, other propellants may be used.

(22) Especially in case the catalyzing reactor 1 is used as thruster, the entrance 2 and the exit 3 of the reactor 1 may be in a mutually space apart plane while preserving the complex internal reactor structure 4 of reciprocating channels 5.

(23) Further, due to the complex internal structure 4 of the reactor 1, the reactor is preferably made by a manufacturing process wherein successive layers of material are added to each other to form the reactor 1.

(24) The catalytic reactor may be used as a thruster having an improved cold start performance in space propulsion. The catalytic reactor may decompose a medium, preferably a gaseous or liquid medium, into an accelerated superheated gas to provide for thrust for a spacecraft.

(25) The catalytic reactor with its complex internal structure may relatively easily and inexpensively be manufactured using an additive layer method, e.g. 3D printing or laser sintering. Using an additive layer method, a complex internal structure can be made, for example, a honeycomb structure with thin walled reciprocating channels which are also leak tight or porous such that the reacting medium cannot escape from the channel. Preferably, a heat conducting catalytic material is used, for example, silver. The powder used for the production of the reactor may comprise some additives for improving the 3D printing process or optimizing the i.e. mechanical characteristics of the reactor, e.g. an amount of copper. However, the presence of copper or another support material that is mixed with silver may affect the efficiency of the catalyzing reactor. In such a case, an additional coating process step may be applied to improve the performance of the bed. The reactor is produced under computer control. The computer uses a 3D image file to obtain the cross sections of reactor. The reactor is produced by first applying a thin layer of powdered material onto a bed. Then a high power laser is applied in two dimensions, to fuse the layer of powdered material according to a predetermined pattern. The powdered bed is then lowered and a new layer of powdered material is applied onto bed and the laser radiation is applied again to fuse a new layer such that a three dimensional object can be formed. The powdered material is a powdered catalyst or a powdered catalyst support material. When the powdered material is not a catalyst but a catalyst support material, optionally a catalytic material may be applied to the shaped object. Another advantage of this process method is that control over the production of the reactors by additive manufacturing enables more reproducible reactors.

(26) As for the purpose of this disclosure, it is pointed out that technical features which have been described may be susceptible of functional generalization. It is further pointed out that—insofar as not explicitly mentioned—such technical features can be considered separately from the context of the given exemplary embodiment, and can further be considered separately from the technical features with which they cooperate in the context of the example.

(27) It is pointed out that the invention is not limited to the exemplary embodiment represented here, and that many variants are possible.

(28) For example, the channels within the reactor may extend along the longitudinal axis of the reactor. However, in alternative embodiments of the catalyzing reactor, the channels may also extend along a transverse axis of the reactor. Further, the flow path may be spiral or helical. It is further noted that it is also possible that the reaction that takes place in the channel may not be exothermal. In that case the upstream portion of the flow path may transfer heat to the downstream portion of the flow path. Particularly, heat may be redistributed over the reactor during non-stationary and/or stationary functioning. Such variants will be clear to the skilled person, and are considered to be within the scope of the invention as defined in the appended claims.