HEAT EXCHANGER

Description

[0001] The invention relates to a heat exchanger, in particular a heat exchanger which can be used modularly for a dehumidifier.

[0002] Non-nuclear-powered submarines are increasingly using fuel cell systems to enhance their operational capability while submerged. A key type of fuel cell is the recirculating fuel cell. However, the gas flowing in the recirculation loop must be dehumidified. This is achieved by cooling the gas in a first heat exchanger, causing the water to condense out. In a second heat exchanger, the gas is reheated so that it enters the fuel cell at approximately its operating temperature, thus minimizing aging, particularly of the membrane.

[0003] This results in several requirements for the heat exchangers used under these conditions. In addition to a compact design, high efficiency with the lowest possible flow resistance is necessary. Furthermore, a certain degree of modularity is advantageous.

[0004] From DE 10 2020 210 532 B3 a dehumidifier for a recirculation circuit of a fuel cell device is known.

[0005] A plate heat exchanger is known from DE 10 2020 210 310 A1.

[0006] A heat exchanger according to the preamble of claim 1 is known from JP H10-30893 A.

[0007] A heat exchanger is known from JP H11-23182 A.

[0008] A cross-flow heat exchanger is known from US patent 2010 / 0285727 A1.

[0009] A heat exchanger is known from WO 2009 / 003817 A2.

[0010] A heat exchanger is known from CH 611 819 A5.

[0011] The object of the invention is to provide a heat exchanger that can be used, in particular, in a dehumidifier of a recirculation circuit of a recirculation fuel cell on board a submarine.

[0012] This problem is solved by the heat exchanger with the features specified in claim 1. Advantageous further developments are described in the dependent claims, the following description, and the drawings.

[0013] The heat exchanger according to the invention has a rectangular base shape. For example, the heat exchanger can be cuboid, and in particular cube-shaped. The base shape refers here to the internal area through which the fluid flows. On the outside, features necessary for mounting additional components can be arranged. Likewise, the internal area can have inlet and / or outlet areas attached to the rectangular base shape. The heat exchanger has a first side and a second side of the rectangular base shape, with the first side and the second side being opposite each other. Thus, the first side and the second side are parallel to each other. Tubes are arranged between the first side and the second side. Such a heat exchanger is also referred to as a shell-and-tube heat exchanger.

[0014] According to the invention, the pipes have an elliptical cross-section. In an ellipse, the sum of the distances of any point on the ellipse (i.e., any point on the surface, here the pipe) from any two predetermined points, the foci, is the same for all points. The ellipse thus represents a special form of the oval. The elliptical shape optimizes the flow resistance for a gas flowing through the heat exchanger while simultaneously ensuring effective heat exchange with the heat exchange medium flowing in the pipes. At the same time, the oval shape optimizes use in a cooling heat exchanger, where condensation occurs. The elliptical shape allows the condensate to drain efficiently downwards, enabling counterflow dehumidification.

[0015] The advantage of the elliptical shape is that its symmetry allows for independent flow direction. Therefore, such a heat exchanger can be used particularly efficiently in a modular design.

[0016] In a further embodiment of the invention, all principal axes of the elliptical tubes are arranged parallel. Preferably, all principal axes are perpendicular to the first side and the second side.

[0017] According to the invention, a distributor head for introducing a heat exchange medium is arranged on the first side of the heat exchanger, and a collector head for discharging the heat exchange medium is arranged on the second side of the heat exchanger. Preferably, the heat exchanger and the distributor head, as well as the heat exchanger and the collector head, can be connected to one another by means of screws or welding. This separate design is particularly practical for a modular construction. Furthermore, this allows for installation or replacement even in confined spaces, for example, and especially in a fuel cell device on board a submarine. At the same time, the modular design allows for the use of essential modules for multiple components. In addition, different manufacturing techniques can be used for the various modular components. According to the invention, the distributor head and the collector head have a pyramidal shape.The apex of the pyramidal shape can preferably be flattened (truncated pyramid). This allows the heat exchange medium to be distributed across all tubes and ensures uninterrupted return flow. A connection for supplying or discharging the heat exchange medium can be located either on the top surface of the truncated pyramid or on one of its side faces. In particular, the pyramidal base can also be rounded, especially at the outermost end, for example, to facilitate mounting on the rectangular base of the heat exchanger and to optimize internal flow.

[0018] According to the invention, the distributor head and the collector head are identical in construction. This allows fluid to flow in both directions, and also reduces the number of different components, thus simplifying both manufacturing and spare parts inventory.

[0019] In a further embodiment of the invention, the distributor head and the collector head each have at least one first and one second connection, wherein the first and second connections are suitable for connection to a heat exchange medium distribution system, and wherein the first and second connections are arranged spatially differently. During normal operation, the heat exchange medium distribution system is connected only to the first or the second connection, and the other is closed. This makes it possible to address different steric requirements with only one distributor head or collector head. For example, the first connection is arranged centrally and horizontally, and the second connection is arranged at an angle.Alternatively, the first connection can be directed upwards and the second connection downwards, which is particularly useful in a tower-shaped arrangement, for example in a cascaded series connection to extend the heat exchanger, since then the upper first connection of the lower heat exchanger can be connected to the lower second connection of the upper heat exchanger.

[0020] In a further embodiment of the invention, the heat exchanger has a third and a fourth side of the rectangular base, wherein the third and fourth sides are opposite each other. Thus, the third and fourth sides are parallel to each other. Due to their perpendicularity, the third and fourth sides are each perpendicular to the first and second sides, respectively. The elliptical cross-section of the tubes is arranged such that the principal axes of the elliptical cross-sections are perpendicular to the third and fourth sides. This results in minimal flow resistance for a fluid flowing from the third to the fourth side. Preferably, the fluid is introduced through the third side and flows out through the fourth side. The fluid can, in particular, be a moisture-laden gas.The fluid can be a gas containing gaseous water or it can contain liquid water, for example in droplet form. Preferably, a liquid phase can condense out of the fluid in the heat exchanger or be separated in some other way.

[0021] In a further embodiment of the invention, the gas passage in the third and fourth sides extends over at least 80%, preferably at least 90%, of the surface area of ​​the third and fourth sides, respectively. Thus, apart from the necessary side wall and, for example, connecting elements, the gas passage occurs as completely as possible through the third and fourth sides. This is particularly advantageous when at least two heat exchangers are to be arranged one above the other, for example, to form a dehumidifier or to create a longer heat exchanger using a modular design.

[0022] In a further embodiment of the invention, the third side is designed for direct connection with the fourth side of another heat exchanger according to the invention. This allows two or more heat exchangers to be easily stacked on top of each other.

[0023] In a further embodiment of the invention, the third side of the heat exchanger can be connected to the fourth side of another heat exchanger according to the invention. This allows the heat exchanger to be extended in a modular design. In this case, the heat exchange medium preferably flows first through the first heat exchanger and then through the second heat exchanger, while the gas flows first through the second heat exchanger and then into the first heat exchanger. Alternatively, and more preferably, the lower second heat exchanger is operated as a cooler and thus a dehumidifier, and the upper first heat exchanger as a heater, so that the combination of the two heat exchangers results in dehumidification with no or only a minimal temperature change of the gas flowing from the incoming to the outgoing gas.

[0024] In a further embodiment of the invention, the heat exchanger has a fifth and a sixth side of the rectangular base, with the fifth and sixth sides being opposite each other. The fifth and sixth sides each have a closed surface. The closed surface preferably consists of successive semi-ellipses, which have the same shape as the tubes. Two embodiments result when assuming tubes arranged in a staggered row. The semi-ellipses can alternately point inwards and outwards. This results in a corrugated surface, which provides a relatively constant distance between the tubes and between the tubes and the outer wall. Alternatively, all semi-ellipses are preferably convex.

[0025] In a further embodiment of the invention, the heat exchanger is rotationally symmetrical about a first twofold axis of rotation, the first axis of rotation being perpendicular to the first and second sides. The advantage of this is that, with a bottom-to-top flow, the heat exchanger can be installed in any orientation. This means that the third and fourth sides are identical, as are the fifth and sixth sides. This simplifies installation, replacement, and maintenance, especially in confined spaces, such as in a fuel cell device on board a submarine, making it less prone to errors. The heat exchanger then only distinguishes between an "inlet" and an "outlet" for the heat exchange medium; the "top" and "bottom" positions can be interchanged during installation.

[0026] In a further embodiment of the invention, the heat exchanger is rotationally symmetrical about a second twofold axis of rotation, the second axis being perpendicular to the third and fourth sides. The advantage of this is that the heat exchanger can thus be installed in any direction in the heat exchange medium circuit. This means that the first and second sides are identical, as are the fifth and sixth sides. This results in simpler and less error-prone installation, replacement, or maintenance, especially in confined spaces, for example, in a fuel cell device on board a submarine. In this embodiment, only the "top" and "bottom" orientation needs to be considered during installation.

[0027] In a further embodiment of the invention, the pipes are arranged in rows. Adjacent rows are offset by half the distance between the centers of adjacent pipes in a row.

[0028] In a further embodiment of the invention, the pipes have an outwardly directed thickening of the wall thickness at at least one end. In this case, the inner diameter and thus the flow resistance for the heat exchange medium preferably remains constant. This results in improved power transmission.

[0029] In a further embodiment of the invention, the heat exchanger is manufactured using additive manufacturing. In particular, the heat exchanger is manufactured from a metal powder using laser beam melting.

[0030] In another aspect, the invention relates to a dehumidifier with a first heat exchanger and a second heat exchanger according to the invention. The first heat exchanger is arranged below the second heat exchanger. The third side of the second heat exchanger is connected to the fourth side of the first heat exchanger. The first heat exchanger is configured for cooling, and the second heat exchanger is configured for heating. A water drain is arranged below the first heat exchanger to remove condensate that is separated from a gas stream in the dehumidifier. The advantage is that a dehumidifier can be built using a simple, modular design. This allows for a compact design of the individual components and, at the same time, a very small number of different components.This means that such a dehumidifier is particularly suitable for use in very compact and confined spaces, for example in a fuel cell device on board a submarine.

[0031] In another aspect, the invention relates to a recirculating fuel cell module, wherein the recirculating fuel cell module comprises at least one fuel cell stack and at least one first dehumidifier according to the invention. The fuel cell stack has at least one first inlet and one first outlet. The first outlet is fluidically connected to the third side, and the fourth side is fluidically connected to the first inlet. The first dehumidifier is particularly preferably arranged on the cathode side. Optionally, the recirculating fuel cell module has a second dehumidifier, wherein the second dehumidifier is arranged on the anode side. The modular design allows for quick installation and removal, and thus replacement, of the recirculating fuel cell module.

[0032] In another aspect, the invention relates to a fuel cell device with a dehumidifier according to the invention. Preferably, the dehumidifier is arranged in the recirculation circuit of the fuel cell device.

[0033] In another aspect, the invention relates to a submarine with a fuel cell device according to the invention.

[0034] The heat exchanger according to the invention is explained in more detail below with reference to an embodiment shown in the drawings. Fig. 1 View of first page Fig. 2 View of third page Fig. 3 View of page five Fig. 4 Dehumidifier

[0035] In Fig. 1 The view of the first page 10 is shown. The pipes 70 are visible, which are arranged in staggered rows and whose main axis 72 is arranged perpendicular to the third page 30 and to the fourth page 40.

[0036] Fig. 2 The view shows the third page 30; the pipes 70 run from the first page 10 to the second page 20.

[0037] In Fig. 3 The view shows the fifth side. A distributor head 12 is arranged on the first side 10, for example, welded in place. The heat exchange medium entering through the heat exchange medium inlet 90 is distributed by the distributor head 12 to the tubes 70. The heat exchange medium exiting the tubes 70 on the second side is collected in the manifold 22 and directed to the heat exchange medium outlet 92. The gas enters the heat exchanger at the bottom through the gas inlet on the third side and exits again through the gas outlet 82 on the fourth side 40.

[0038] In Fig. 4 A dehumidifier consisting of two heat exchangers is shown, with the representation of the representation of the Fig. 3This corresponds to the view on the fifth side. The heat exchange medium enters the lower heat exchanger via the heat exchange medium inlet 90 and cools and dehumidifies the gas stream. The heat exchange medium leaves the lower heat exchanger and passes through the connecting line 100 into the upper heat exchanger. There, the heat is transferred back to the cooled and dehumidified gas, thus bringing it back to approximately its initial temperature. The heat exchange medium leaves the upper heat exchanger through the heat exchange medium outlet 92. Reference sign

[0039] 10 first page 12 distributor head 20 second page 22 manifold head 30 third page 40 fourth page 70 pipe 72 main shaft 80 gas inlet 82 gas outlet 90 heat exchange medium inlet 92 heat exchange medium outlet 100 connecting line

Claims

1. Heat exchanger, wherein the heat exchanger has a rectangular basic shape, wherein the heat exchanger has a first side (10) and a second side (20) of the rectangular basic shape, wherein the first side (10) and the second side (20) are opposite one another, wherein tubes (70) are arranged between the first side (10) and the second side (20), wherein the tubes (70) have an elliptical cross-section, wherein a distributor head for introducing a heat exchange medium is arranged on the first side (10) of the heat exchanger, wherein a collecting head for discharging the heat exchange medium is arranged on the second side (20) of the heat exchanger, characterised in that the distributor head and the collecting head have a pyramidal basic shapeand that the distributor head and the collecting head are of identical construction.

2. Heat exchanger according to claim 1, characterised in that the heat exchanger has a third side (30) and a fourth side (40) of the rectangular basic shape, the third side (30) and the fourth side (40) being opposite each other, the elliptical cross-section of the tubes (70) being arranged such that the main axes of the elliptical cross-sections are arranged perpendicular to the third side (30) and fourth side (40).

3. Heat exchanger according to claim 2, characterised in that the third side (30) of the heat exchanger can be connected to the fourth side (40) of a further heat exchanger according to the invention.

4. A heat exchanger according to any one of the preceding claims, characterised in that the heat exchanger has a fifth side and a sixth side of the basic rectangular shape, the fifth side and the sixth side being opposite each other, the fifth side and the sixth side having a closed surface, the closed surface consisting of successive half ellipses having the same shape as the tubes (70).

5. Heat exchanger according to one of the preceding claims, characterised in that the tubes (70) are arranged in rows, with each adjacent row having an offset of half the distance between the centres of adjacent tubes (70) in a row.

6. Heat exchanger according to one of the preceding claims, characterised in that the tubes (70) have an outwardly directed thickening of the wall thickness at at least one end.

7. Dehumidifier with a first heat exchanger according to one of the preceding claims and a second heat exchanger according to one of the preceding claims, wherein the first heat exchanger is arranged below the second heat exchanger, wherein the first heat exchanger is connected for cooling, wherein the second heat exchanger is connected for heating, wherein a water drain is arranged below the first heat exchanger.

8. Fuel cell device with a dehumidifier according to claim 7.

9. A submarine with a fuel cell device according to claim 8.