Device for measuring impurities in a flow channel

Abstract

The invention relates to a device for measuring impurities in a flow channel (1), comprising two measuring electrodes (2) provided in the flow channel (1) so as to not contact each other. The aim of the invention is to allow a reliable detection of impurities, in particular locally limited impurities, largely independently of the flow conditions and the flow channel geometries. This is achieved in that the measuring electrodes (2) have multiple through-openings (7) which are adjacent transversely to the flow direction (3) and each of which is delimited by a conductor portion (8).

Description

[0001] Device for measuring impurities in a flow channel

[0002] Technical field

[0003] The invention relates to a device for measuring impurities in a flow channel with two measuring electrodes arranged in the flow channel without contact with each other.

[0004] State of the art

[0005] US Patent 20060185977A1 ​​discloses a device for measuring impurities in a liquid flowing through a flow channel. For this purpose, several rod-shaped measuring electrodes, supplied with voltage via an electrical circuit, are arranged in the flow channel without contact with each other, i.e., spaced apart in the direction of flow. Following the amperometric measuring principle, impurities in the liquid can be quantified by the current measured in the circuit if the impurities undergo a redox reaction with the measuring electrodes. A disadvantage of this method, however, is that impurities can only be detected if they contain redox-active components.Furthermore, the problem arises that, especially at high flow velocities of the liquid being analyzed, the short residence time of the contaminant and / or large flow channel diameters result in insufficient interaction between the measuring electrodes and the contaminants due to steric conditions. Consequently, the contaminants pass through the measuring electrodes undetected, or their measurement signals become unreliable. Solids or locally confined contaminants, in particular, can pass through the measuring electrodes undetected. [Representation of the invention.]

[0006] The invention is therefore based on the objective of proposing a device for measuring impurities in a liquid flowing through a flow channel, which allows reliable detection of impurities, in particular locally occurring impurities, largely independent of the flow conditions and the flow channel geometries.

[0007] The invention solves the stated problem by providing the measuring electrodes with several adjacent through-openings perpendicular to the flow direction, each bounded by a conductor section. A flow suction effect is created in the flow channel through the through-openings of the measuring electrodes, forcing the impurities towards the conductor sections. This makes the impurities more spatially accessible to the conductor sections, both for potential redox reactions and for actual contact. In this way, a measured signal or a measured signal change by the measuring electrodes can indicate not only dissolved impurities resulting from redox reactions at the measuring electrode, but also conductive solids resulting from contact between the solid and the measuring electrode.The through-holes, which are adjacent perpendicular to the flow direction, can be evenly distributed across the measuring electrode surface, thus facilitating interaction between contaminants and the measuring electrodes. The number, size, and distribution of the through-holes on the measuring electrode, and the associated design of the conductor sections bordering the through-holes, allow the measuring electrode to be adapted to different flow conditions and liquids to be analyzed. The device is preferably used for measuring contaminants in a coolant, particularly battery coolant. To create advantageous measuring conditions for coolants or liquids with similar rheological properties, at least 10, preferably at least 50, and more preferably at least 100 through-holes adjacent perpendicular to the flow direction can be provided per measuring electrode.The free diameter of the passage openings, together with the distance between the measuring electrodes, determines the measuring volume, i.e., the volume that a contaminant must occupy at least in order to be reliably detected by the device according to the invention.

[0008] The device can include a contamination quantification unit for quantifying the measured contamination. This allows the contamination to be quantified continuously and directly during the measurement without having to modify the measurement setup. The contamination quantification unit can, for example, be a separate current measuring device, in particular an ammeter, which is connected to the measuring electrodes via an electrical circuit. A voltage source can also be arranged in the circuit. This results in a device for measuring contaminants in a flow channel with two measuring electrodes arranged without contact to each other in the flow channel, which are connected via an electrical circuit to an current measuring device and a voltage source, wherein the measuring electrodes have several adjacent through-openings perpendicular to the flow direction, each bounded by a conductor section.Preferably, the measuring electrodes are supplied with a voltage of 0.1 V to 100 V, more preferably 0.1 V to 50 V, and particularly 1 to 10 V. The best results with regard to measuring accuracy and device robustness can be achieved at voltages of 2 V to 6 V, and particularly at 3 V to 4 V.

[0009] A simple way to ensure that the measuring electrodes are not in contact with each other can be achieved by spacing them apart in the direction of flow. However, to enable a particularly compact device, the conductor sections of the different measuring electrodes can be arranged at an angle to each other, lie partially in the same plane, and be kept in contact with each other by insulators provided at the intersection points. This way, the measuring electrodes are electrically isolated from each other, and any current flow only occurs via impurities in the flow channel.It has been found that contaminants can be detected with a sufficiently high probability, without incurring excessive flow losses, if at least one measuring electrode, and in particular all measuring electrodes, extend transversely to the flow direction over at least 50%, preferably at least 80%, of the free cross-sectional area of ​​the flow channel. This means that the surface, i.e., the area of ​​the outline of the measuring electrode, extends over at least 50%, preferably at least 80%, of the free cross-sectional area of ​​the flow channel. Preferably, the measuring electrode is arranged centrally in the flow channel. The free cross-sectional area of ​​the flow channel is defined as the unobstructed cross-sectional area through which the liquid can flow freely.

[0010] Preferably, at least one measuring electrode, and in particular all measuring electrodes, can extend over the entire free cross-sectional area of ​​the flow channel, thereby further reducing the probability of failing to detect contaminants. To avoid excessively increasing flow losses and thus enable resource-efficient operation of the device, it is proposed that at least one measuring electrode be a screen, and preferably that all measuring electrodes be screens. This has the further advantage that the measuring electrodes can function as separating elements and thus not only detect but even prevent the passage of particularly coarse contaminants. This allows sensitive components to be installed upstream and provides them with protection.Advantageously, the sieves are detachably arranged in the flow channel, allowing for easy cleaning by removing the sieve from the channel. For this purpose, the flow channel can have a sealable slot through which the sieve is inserted. In the case of sieves serving as measuring electrodes, the conductive sections can be formed by grid sections of the sieve. In principle, various measuring principles can be used in conjunction with the measuring electrodes. For example, the presence of electrically conductive contaminants can be measured by the change in capacitance between the measuring electrodes. Particularly advantageous measuring conditions, especially in connection with coolant fluids, result from amperometric measurement.This means that the current flowing between the non-contact, preferably spaced-apart, measuring electrodes when a voltage is applied is proportional to the detected impurities. Charge transport between the measuring electrodes in the flow channel occurs via redox-active components in the liquid being analyzed, or via solid conductors as impurities that contact both measuring electrodes simultaneously. To increase the probability of the solid impurities contacting one or both measuring electrodes, the openings of the spaced-apart measuring electrodes can be offset from each other. This can be achieved, for example, by arranging the preferably identical measuring electrodes at an angle to each other around a longitudinal axis of the flow channel.Should a contaminant pass through the orifice of the upward-facing measuring electrode without contact, the angular offset of the downstream measuring electrode promotes contact between it and the contaminant. The resulting turbulent flow between the measuring electrodes further increases the probability of contact between the upward-facing electrode and the measuring electrode. The collision probability can be further increased by offsetting the orifices of the spaced measuring electrodes.

[0011] To minimize flow losses, the proportion of all cross-sectional areas of the through-holes relative to the largest outline area of ​​the measuring electrode can be at least 5%. Preferably, the proportion of all cross-sectional areas of the through-holes relative to the largest outline area of ​​the measuring electrode is at least 30%. This measure ensures a sufficient free flow cross-section despite small measurement volumes and thus good spatial resolution.

[0012] Contact between typical contaminants found in battery coolants and the measuring electrodes is achieved when the ratio of the largest diameter of the through-holes to the diameter of the measuring electrodes is 0.001 to 0.01. The through-holes can have different geometric cross-sectional areas, preferably rectangular or oval, and more commonly circular. For through-holes with a rectangular cross-sectional area, the diagonal is considered the largest diameter. When using the device in temperature control systems for battery temperature control, it is recommended that the largest diameter of the through-hole be 0.1 to 2 mm.

[0013] To further promote the simultaneous contact of both measuring electrodes by a solid impurity, it is proposed that the ratio of the distance in the flow direction between the two measuring electrodes to the diameter of the measuring electrodes be less than 2, preferably less than 1, and particularly less than 0.5. This creates a sufficiently small measuring volume between the measuring electrodes in which an impurity is likely to electrically connect both measuring electrodes with a sufficiently high probability, thus enabling a detectable current flow. Preferably, the distance in the flow direction between the two measuring electrodes can be 0.05–1 mm.

[0014] To achieve high spatial measurement resolution at high flow velocities with a small conductor cross-section, at least one spacer can be provided between the measuring electrodes. This spacer can isolate the measuring electrodes from each other, thus preventing deformation-induced contact between the electrodes despite the small distance required for a small measuring volume, and the associated false signal. Simultaneously, the spacer can act as a vibration damper, allowing the measuring electrodes to stabilize even at high flow velocities, thereby improving measurement conditions.

[0015] Brief description of the invention

[0016] The invention is illustrated in the drawing as an example. It shows

[0017] Fig. 1 is a schematic side view of the device according to the invention, Fig. 2 is a top view of a measuring electrode according to a first embodiment in an enlarged scale,

[0018] Fig. 3 shows a top view of a measuring electrode according to a second embodiment of the invention, to the same scale and

[0019] Fig. 4 shows a schematic representation of a detail of a device according to the invention in a third embodiment.

[0020] Ways to implement the invention

[0021] A device according to the invention for measuring impurities in a flow channel 1, in particular for measuring impurities in a coolant flow for temperature control of battery cells of a battery module, has, as can be seen in Fig. 1, at least two measuring electrodes 2 which are arranged without contact with each other. This can be achieved by spacing the measuring electrodes 2 apart from each other in the flow direction 3. The measuring electrodes 2 can be connected to each other via a circuit 4 comprising a voltage source 5. If the circuit 4 is closed via the measuring electrodes 2 by impurities located in the flow channel 1, for example, conductive solids or dissolved redox-active components, a current flow can be detected by an ammeter 6 as a contamination quantification unit, which indicates the presence of a contamination and, in particular, quantifies it.According to the invention, the measuring electrodes 2 have several adjacent through-openings 7 perpendicular to the flow direction 3, each of which is bounded by a conductor section 8. The through-openings 7, through which the coolant flows, force the contaminants into a flow path, so that they are guided towards the conductor sections 8, thereby improving the interaction between the contaminant and the measuring electrodes 2 and thus the measurement sensitivity.

[0022] The measuring electrodes 2 can extend transversely to the flow direction 3 over at least 50% of the free flow channel cross-sectional area 9, in particular over the entire flow channel cross-sectional area 9, whereby the contaminants can be detected distributed over the entire flow channel cross-section.

[0023] An advantageous design of the measuring electrodes 2 is achieved by using sieves, which can be designed as a grid (Fig. 2) or as a perforated sheet (Fig. 3). The sieves allow particularly coarse contaminants to be separated from the coolant, thus protecting downstream components.

[0024] As indicated in Fig. 1, the measuring electrodes 2 can be arranged in the flow channel 1 at an angle to each other about a longitudinal axis 10 of the flow channel, so that the openings 7 of the spaced-apart measuring electrodes 2 are offset from each other, thereby increasing the probability of a collision of a contaminant with the conductor sections 8. In particular, the measuring electrodes 8 can be of identical construction.

[0025] As indicated in Fig. 2, the ratio of the largest diameter 11 of the through-holes 7 to the diameter 12 of the measuring electrodes 2 can be 0.008 - 0.009. According to Fig. 3, the ratio can be 0.003 - 0.004.

[0026] The ratio of the distance 13 in the flow direction 3 between the two measuring electrodes 2 to the diameter 12 of the measuring electrodes 2 is preferably less than 2, more preferably less than 1. The distance 13 can be 0.05–1 mm to achieve sufficient measurement resolution. To prevent short circuits and reduce vibrations, a preferably annular spacer 14 can be provided against which the measuring electrodes 2 are supported. The spacer 14 can be an insulator.

[0027] Fig. 4 shows an alternative embodiment for making the measuring electrodes 2 contactless with each other in accordance with the invention. Here, the conductor sections 8 of the different measuring electrodes 2 can be arranged at angles to each other, preferably transversely to each other, and lie partially in a plane. At the intersection points 15, the conductor sections 8 of the different measuring electrodes 2 do not lie in a plane and are held contactless with each other by a spacer 14 acting as an insulator.

Claims

Patent claims 1. Device for measuring impurities in a flow channel (1 ) with two measuring electrodes (2) arranged in the flow channel (1 ) without contact with each other, characterized in that the measuring electrodes (2) have several passage openings (7) adjacent transversely to the flow direction (3), each of which is bounded by a conductor section (8).

2. Device according to claim 1, characterized in that at least one measuring electrode (2) extends transversely to the flow direction (3) over at least 50% of the free flow channel cross-sectional area (9).

3. Device according to claim 2, characterized in that at least one measuring electrode (2) extends transversely to the flow direction (3) over the entire free cross-sectional area (9) of the flow channel.

4. Device according to one of claims 1 to 3, characterized in that at least one measuring electrode (2) is a sieve.

5. Device according to one of claims 1 to 4, characterized in that the passage openings (7) of the spaced-apart measuring electrodes (2) are offset from each other.

6. Device according to one of claims 1 to 5, characterized in that the proportion of all cross-sectional areas of the through-openings in relation to the largest outline area of ​​the measuring electrode is at least 5%.

7. Device according to one of claims 1 to 6, characterized in that the ratio of the largest diameter (11) of the through-holes (7) to the diameter (12) of the measuring electrodes (2) is 0.001 - 0.

01.

8. Device according to any one of claims 1 to 7, characterized in that the ratio of the distance (13) in the flow direction (3) between the two measuring electrodes (2) to the diameter (12) of the measuring electrodes (2) is less than 2, preferably less than 1.

9. Device according to any one of claims 1 to 8, characterized in that the distance (13) in the flow direction (3) between the two measuring electrodes (2) is 0.05 - 1 mm.

10. Device according to one of claims 1 to 9, characterized in that at least one spacer (14) is provided between the measuring electrodes (2).

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