Liquid separator

Abstract

The invention relates to a liquid separator (17) for a gas stream carrying liquid, having an inner volume space (21) with at least one impact element (23) and with a collection region (24) for the separated liquid, characterized in that in the collection region (24) a heat-conducting element (30) made of a material that conducts heat well is arranged, which projects into the gas stream (25) in the inner volume space (21) in the direction of the at least one impact element (23), wherein the impact element (23) is composed of a material that conducts heat worse than the heat-conducting element (30).

Description

Technical Field

[0001] This invention relates to a liquid separator for a liquid-carrying gas stream, the type detailed in the preamble of claim 1. The invention also relates to applications of such a liquid separator. Background Technology

[0002] Liquid separators or water separators are known in principle from the prior art. These liquid separators typically have impingement elements at which a liquid-carrying gas stream abruptly changes its flow direction, thereby separating the liquid and causing it to flow down the impingement elements, for example, due to gravity. A corresponding example is shown in DE 3109 240A1.

[0003] Liquid separators are now frequently used in fuel cell systems, where separating water from the fuel cell exhaust is crucial because this water, typically a byproduct of fuel cells, is prone to freezing due to its purity. This can cause problems at temperatures near the freezing point, particularly affecting fuel cell startup, as components and / or flow paths may become blocked by ice. In this regard, for example, DE 10 2007 023 417 A1 describes a water separator in which a heat-conducting element connected to an electrically heated element allows the water separator to be heated and thawed as needed.

[0004] While this thawing, which is performed when needed, ensures the functionality of the structure, it is complex in terms of structural design and typically incurs additional electrical energy demands, which adversely affects the overall energy balance of such a system. Summary of the Invention

[0005] Therefore, the object of the present invention is to describe an improved liquid separator that avoids these disadvantages and ensures efficient operation with reduced risk of icing, at least during operation.

[0006] According to the invention, this objective is achieved by a liquid separator having the features of claim 1, and in particular the features of the characterizing portion of claim 1. Advantageous designs and improvements are derived from the associated dependent claims. Furthermore, a particularly preferred application of such a liquid separator is described in claim 10.

[0007] The liquid separator according to the invention has an internal volume space having at least one impact element, as in the prior art. In addition to the impact element, a collection area for the separated liquid is typically arranged in the volume space such that, in the intended use, the collection area is located below the impact element along the direction of gravity, or in the lower region of the impact element, so that the separated liquid reaches the collection area by gravity.

[0008] According to the present invention, a heat-conducting element made of a thermally conductive material is arranged in the collection area. The heat-conducting element extends into the gas flow within the volume space toward the impact element. The impact element itself is made of a material with lower thermal conductivity than the heat-conducting element. This causes the liquid to be separated at the impact element, as in a conventional liquid separator. The liquid then drips downwards, for example, due to gravity, and either drips or flows into the collection area. A heat-conducting element in contact with the liquid is present in the collection area, extending from the collection area toward the gas flow and thus toward the impact element. Its function is to separate the liquid and drip downwards when the fluid carrying droplets encounters the impact element. Due to the poor thermal conductivity of the impact element, the separated liquid remains relatively warm. The gas flow, with its droplets largely removed, then flows at least partially along the heat-conducting element, transferring its heat to the element, which in turn introduces this heat into the collection area and the liquid collected there. Thus, heat is transferred to the collection area through the separated droplets and the heat-conducting element. Therefore, the collection area can be passively and effectively heated without the need for external heating or connection to electric heating elements, heat exchangers through which the heated medium flows, or similar devices, although these devices are still possible and conceivable as supplements. Thus, it is possible to largely prevent, or at least significantly reduce, the conversion of liquid to solid state, such as freezing when it is water, compared to existing structures.

[0009] A highly advantageous improvement to this approach is that, in this configuration, the heat-conducting element is connected to the impact element, so that in any case, the largest portion or preferably all of the gas flow is in contact with the heat-conducting element and can transfer heat to it.

[0010] This demonstrates that the structure of the heat-conducting element extending into the impact element, and the design of the corresponding heat-conducting element having good thermal conductivity while the impact element has poor thermal conductivity, is particularly advantageous in terms of heat transfer to the collection region. The connection ensures that the entire volumetric flow of the gas is largely in contact with the heat-conducting element. On the other hand, because the heat-conducting element is designed differently from the impact element in terms of its material and thermal conductivity, it can be made much shorter in total length than the impact element. This ensures that heat is effectively transferred to the collection region along a relatively short path. If the impact element were also made of a metal with good thermal conductivity, the heat previously absorbed and / or acquired from the droplet would be transferred back to the gas flow en route. Therefore, the original objective of this structure—to input heat into the collection region—is much less effective than the structure with a heat-conducting element with good thermal conductivity and an impact element with poor thermal conductivity. This is particularly advantageous when these elements are designed according to the structure described below.

[0011] A particularly advantageous improvement to the liquid separator according to the invention is that the heat-conducting element is made of metal, preferably of a metal alloy with good thermal conductivity, such as an aluminum alloy. The impact element can be made of plastic, which, correspondingly, has much poorer thermal conductivity than the metal of the heat-conducting element. Thus, the aforementioned advantages are ideally utilized.

[0012] Furthermore, according to another highly advantageous design of a variant of the liquid separator that connects the heat-conducting element to the impact element, the heat-conducting element can be implemented as a two-piece unit. This heat-conducting element includes, for example, a plate arranged in a region of the collection area and a connecting element between the heat-conducting plate and the impact element. The connecting element can be connected to the impact element, for example, via a plug-in connection or a clip connection.

[0013] Furthermore, another highly advantageous design of the liquid separator according to the invention is provided in which the heat-conducting element has one or more plates, or, according to the embodiment just described, at least the connecting element has one or more plates, said one or more plates having an area smaller than the cross-section through which the volume space can flow. This structure allows the use of solid plates as heat-conducting elements. These solid plates are thus able to absorb a relatively large amount of heat. These solid plates are designed to occupy a large portion, but not all, of the gas flow cross-section. The gas must then flow along these plates, be deflected accordingly, and then flow out of the liquid separator. Thus, on the one hand, an ideal heat input to the plates of the heat-conducting element is achieved; on the other hand, by deflecting the gas flow again, any liquid that may remain in the gas is separated as it flows through the plates.

[0014] The heat-conducting element, or preferably the connecting element in the above structure, may also have a perforated plate, rod, grille, or similar structure. These structures allow for placement within the gas flow, enabling heat absorption, while also allowing for adequate gas permeability, allowing the gas to approximately "fill" the entire cross-section. This simplifies both the structural design and installation. Furthermore, it allows for reliable gas passage through the perforations, grille structures, or the spacing between rods, which may be configured as intersecting rods contacting each other at their intersections.

[0015] Furthermore, another highly advantageous design of the liquid separator according to the invention allows for a configuration where the housing surrounding the internal volume space of the liquid separator and the impact element are implemented as a single piece. This structure is particularly simple and efficient in terms of manufacturing and assembly. For example, it can be configured such that both the impact element and the housing are made of plastic. This can then be constructed, for example, as a relatively simple injection-molded part, into which a heat-conducting element in the form of a plate is clipped or screwed into the housing to achieve the aforementioned functionality, and preferably the collection area is connected to the impact element.

[0016] Furthermore, another particularly advantageous design of the liquid separator according to the invention can be configured such that exactly one impacting element is disposed within the internal volume space. With proper design, this structure with only a single impacting element is sufficient for many applications, such as water separation in the anode circuit of a fuel cell system, thus ensuring an extremely simple, compact, and inexpensive structure to manufacture.

[0017] Additionally, a further highly advantageous variation of the liquid separator according to the invention can be provided whereby the collection area is connected to the surrounding environment or other components via an outlet valve. Such an outlet valve, especially when it is designed to be immediately adjacent to the collection area, and if necessary integrated with or at least thermally connected to both the liquid separator and the collection area, offers the additional advantage of allowing for the arrangement of a relatively large and heavy component with a high heat capacity at the collection area. This component can also benefit from heating via a heat-conducting element (to prevent freezing) and helps to store heat in the area up to a certain extent. Furthermore, it allows for targeted liquid discharge, for example, based on a measured, simulated, or similarly determined liquid level.

[0018] The liquid separator according to the invention can now be implemented and manufactured accordingly simply and efficiently. In particular, the liquid separator ensures operation without additional heating even under adverse external conditions when the facility in which it is built-in is running, because by transferring heat to the area where the liquid is collected, freezing of the liquid can be largely prevented. This also applies, for example, to water, especially ultrapure water, which freezes very easily even at temperatures near its freezing point. This can be reliably prevented by a structure with heat-conducting elements and heating of the collection area. Therefore, the liquid separator according to the invention is particularly suitable as a water separator, and here especially suitable as a water separator in the exhaust gas stream of a fuel cell, in which pure water, produced as the product water of the fuel cell, is produced, is correspondingly prone to freezing. If the fuel cell is installed, for example, as a fuel cell system in a vehicle that provides electricity, then the possibility of the vehicle operating at temperatures below freezing cannot be ruled out. Therefore, the liquid separator according to the invention is particularly suitable for such applications, but is not limited thereto. Attached Figure Description

[0019] Further advantageous designs and applications of the liquid separator according to the invention are also derived from the embodiments described in detail below with reference to the accompanying drawings. Wherein:

[0020] Figure 1An exemplary vehicle with a fuel cell system is shown, the fuel cell system having a liquid separator as a water separator according to the present invention;

[0021] Figure 2 A cross-section of a possible structure of the liquid separator according to the present invention is shown. Detailed Implementation

[0022] exist Figure 1 The diagram schematically illustrates a vehicle 1, which should have a fuel cell system 2 configured to provide electricity, specifically to provide electric drive power for the vehicle. Here, fuel cells constitute the core of the fuel cell system 2, typically constructed as a stack of individual cells. This structure is also referred to below as a fuel cell stack or fuel cell pile. This structure can, for example, be constructed with a proton exchange membrane as the electrolyte, i.e., a so-called PEM fuel cell. Air is supplied to the cathode side 6 of the fuel cell stack 3 by an air delivery device 4, such as a fluid compressor, via an intake line 5 and a gas / gas humidifier 10 in the embodiment shown here. The oxygen-depleted air flows out from the cathode side 6 of the fuel cell stack 3 again through the gas / gas humidifier 10 via an exhaust line 7. Here, moisture is delivered to the air supply in the intake line 5 via the humidifier 10. The exhaust gas then enters an exhaust gas turbine 8, where it expands to recover thermal and pressure energy. The motor 11 is connected to the exhaust gas turbine 8 on one hand and to the fluid compressor on the other. This structure, also known as the electric turbocharger 20 or the motor-assisted turbocharger, is used to efficiently supply air to the fuel cell system 2, and is known from the prior art in this respect, so it does not need to be discussed further.

[0023] Hydrogen is supplied from the compressed gas storage tank 13 to the anode side 12 of the fuel cell stack 3 via a pressure regulating and metering valve 14. Unconsumed hydrogen is returned from the anode side 12 of the fuel cell stack 3 to the gas jet pump 15, which serves as a recirculation delivery device, via a recirculation line 16, and mixed with fresh hydrogen, which is also used as a propulsion jet for the gas jet pump 15, and then re-delivered to the anode side 12. Alternatively or supplementing the gas jet pump 15, a recirculation blower may also be provided here. Now, a liquid separator 17 is present in the recirculation line 16 or in the structure for recirculating unconsumed hydrogen, referred to as the anode loop, which in the embodiment shown here is connected to the surrounding environment via an outlet valve 18. It is also easy to imagine, for example, connecting it before the exhaust line 7 or, more particularly, after the exhaust turbine 8. All of this is clear to those skilled in the art of fuel cell systems, and therefore does not need to be discussed further.

[0024] The liquid separator 17 or water separator will now be described in particular in detail below. Figure 2 In the illustration, its structure is schematically shown in cross-section. The water separator, the housing marked 19, should, for example, be made of plastic as an injection-molded part. An outlet valve 18 is provided in direct contact with the housing 19 surrounding the internal volume space 21. Now, for the functionality of the liquid separator 17, a striking element 23 is provided upstream after the inlet opening 22 connected to the recirculation line 16. This striking element blocks the entire flow cross-section of the liquid-laden airflow from the recirculation line 16. This striking element 23 can preferably be one piece with the housing 19 and also made of plastic. The liquid-laden droplets flowing from the recirculation line 16 into the internal volume space 21 through the inlet opening 22 collide with this striking element 23 and are sharply deflected. The water contained therein accumulates at the impact element 23 and, as shown herein, drips downwards along the direction of gravity g under the prescribed operating conditions of the liquid separator 17 and along a portion of the housing 19 into a collection area 24 arranged below the portion of the internal volume space 21 through which the gas flows. This collection area is connected to the outlet valve 18. The gas, having been completely or largely removed from the liquid, then flows back upstream through the internal volume space 21 of the liquid separator 17 and through the outflow opening 26 into the recirculation line 16, as indicated by the arrow marked 25.

[0025] A heat-conducting element 30 is present in the collection area 24, extending beyond the collection area in the direction of the gas flow according to arrow 25. This heat-conducting element is made of, for example, aluminum alloy. The heat-conducting element consists of a first plate 31, which is at least partially arranged in the collection area 24 and extends into the liquid collected there, where the liquid is shown through the liquid surface. A connecting element 32 is also made of aluminum alloy and is preferably implemented as a single piece with the plate 31, or at least connected to the plate in a highly thermally conductive manner, such as by welding. The connecting element extends toward the impact element 23 and is preferably mechanically connected to the impact element, such as by snap-fit, riveting, threaded connection, adhesive bonding, or similar means. The connecting element 32 can, in principle, be implemented as a perforated plate, a number of rods, a grid, or a similar structure. A structure consisting of one or more plates is also conceivable, which, perpendicular to the plane of the figure, largely or partially obstruct the flow cross-section of the internal volume space 21. Therefore, in the case of multiple impact elements 23, it is also conceivable to have multiple connecting elements 32 or to connect all of these multiple impact elements to each other with a single connecting element 32.

[0026] The connecting element 32 and the plate 31, which also partially includes the heat-conducting element 30, now absorb heat from the airflow flowing according to arrow 25. This, along with the heat remaining in the droplet due to the impact element 23 being made of plastic and therefore having poor thermal conductivity, results in heat being introduced into the collection area 24 over a relatively short path via the heat-conducting element 30, and more precisely, also includes the heat already contained in the liquid itself. This results in the liquid in the collection area 24 being well heated during the operation of the liquid separator 17 or water separator, thereby avoiding or at least minimizing the risk of freezing.

Claims

1. A liquid separator (17) for a liquid-carrying gas stream, the liquid separator having an internal volume space (21) having at least one impacting element (23) and a collection area (24) for the liquid to be separated, Its features are, A heat-conducting element (30) made of a thermally conductive material is arranged in the collection area (24), the heat-conducting element extending into the gas flow (25) in the internal volume space (21) toward at least one impact element (23), wherein the impact element (23) is made of a material with lower thermal conductivity than the heat-conducting element (30).

2. The liquid separator (17) according to claim 1, Its features are, The heat-conducting element (30) is connected to the at least one impact element (23).

3. The liquid separator (17) according to claim 1 or 2, Its features are, The heat-conducting element (30) is made of metal, and the at least one impact element (23) is made of plastic.

4. The liquid separator (17) according to claim 2, Its features are, The heat-conducting element (30) includes a plate element (31) and a connecting element (32) for the at least one impact element (23).

5. The liquid separator (17) according to claim 1 or 2, Its features are, The heat-conducting element (30) has one or more plates, the one or more plates having an area smaller than the cross-section through which the internal volume space (21) can be flowed.

6. The liquid separator (17) according to claim 1 or 2, Its features are, The heat-conducting element (30) has at least one perforated plate, multiple rods and / or at least one grid.

7. The liquid separator (17) according to claim 1 or 2, Its features are, The shell (19) surrounding the internal volume space (21) and the at least one impact element (23) are implemented in one piece.

8. The liquid separator (17) according to claim 1 or 2, Its features are, It is equipped with exactly one impact element (23).

9. The liquid separator (17) according to claim 1 or 2, Its features are, The collection area (24) has an outlet valve (18), or the collection area (24) is directly connected to the outlet valve, which allows the collection area (24) to be connected to the surrounding environment or other components in a switchable manner.

10. An application of the liquid separator (17) according to any one of claims 1 to 9 as a water separator in the exhaust gas flow of a fuel cell system (2).

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