JP6024544B2 - Biofilm formation sensor and electronic device cooling system - Google Patents

Description

  The present disclosure relates to a biofilm formation sensor and an electronic device cooling system.

  Conventionally, a water treatment method using a sensor for monitoring microbial soil adhesion provided with a metal material subjected to sensitization treatment, and when both of the two chemical injection pumps reach the threshold value, And when this electric potential falls to a normal value, the structure which performs a chemical injection only with one pump is known (for example, refer patent document 1). In this configuration, a reference electrode is provided together with a sensor (a metal material subjected to sensitization) in a test tube, and the potential of the sensor is measured with reference to the reference electrode.

Japanese Patent Laid-Open No. 2001-4590

  By the way, the biofilm which causes microbial corrosion tends to be formed in a portion having a small flow velocity in the flow path (a flow retaining portion). Therefore, in order to detect early signs of biofilm formation at any location in the entire flow path, it is important to perform sensing at a location where the biofilm is likely to be formed in the entire flow path (flow retention portion). Become.

  In this regard, since the configuration described in Patent Document 1 is configured to perform sensing in the test tube, there is a possibility that a sign of biofilm formation cannot be detected early depending on the flow rate in the test tube. For example, when the flow velocity in the test tube is larger than the flow velocity in the other pipe, there is a possibility that the biofilm is formed in the other pipe before the biofilm is detected in the test pipe.

  Therefore, the disclosed technology aims to provide a biofilm formation sensor or the like that can perform sensing at a flow retention portion.

According to one aspect of the present disclosure, a metal electrode disposed in the flow path;
A reference electrode disposed in the flow path;
There is provided a biofilm formation sensor comprising a cover portion formed of a non-metallic material and covering an upstream surface in the flow direction of the metal electrode in the flow path.

  According to the technique of the present disclosure, a biofilm formation sensor or the like that can perform sensing at a flow retention portion is obtained.

It is a figure which shows an example of the electronic device cooling system. It is sectional drawing which shows an example of the arrangement | positioning state of the biofilm formation sensor. It is a figure which shows an example (1st embodiment) of a structure of the copper electrode part 21, (A) is the top view seen from the downstream, (B) is the top view seen from the upstream, (C ) Is a cross-sectional view along line AA in (A). 3 is an exploded view showing an example of a copper electrode portion 21. FIG. It is an image figure from the biofilm formation in the electronic device cooling system 1 to a biofilm removal. It is a figure which shows an example of a structure of copper electrode part 21 'by another example (2nd embodiment), (A) is the top view seen from the downstream, (B) is the top view seen from the upstream (C) is a sectional view along line AA in (A). It is a figure which shows the cooling system 1B for electronic devices which concerns on the comparative example 1. FIG. It is a figure which shows a survey result (test result). It is sectional drawing which shows another example of the arrangement | positioning state of the biofilm formation sensor.

  Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating an example of an electronic device cooling system 1.

In the electronic device cooling system 1, the refrigerant C ₀ is circulated through the circulation line 2 by the driving force of the circulation pump 13, and the electronic device 7 such as an electronic computer is cooled by the cooling unit 3. The cooling unit 3 includes a manifold 4 for diverting the refrigerant C ₀ in the electronic device 7, a rubber tube 5 through which the refrigerant C ₀ exiting the manifold 4 passes, a copper pipe 8, a cooling plate (cooling plate) 6, Is provided. The cooling plate 6 may be provided for each semiconductor device such as an LSI (large-scale integration) mounted on the electronic device 7. In this case, each semiconductor device is individually cooled by the cooling plate 6. As a material for the cooling plate 6, it is preferable to use copper which has a high thermal conductivity and can easily take the heat of the electronic device 7.

The refrigerant C ₀ is optional, but may be formed, for example, by dissolving an inhibitor (corrosion inhibitor) in pure water. As the inhibitor, it is preferable to use benzotriazole effective for preventing corrosion of copper material. In this case, the inhibitor concentration may be, for example, 100 ppm. The copper material of the copper pipe 8 and the cooling plate 6 is stable in a pH range of neutral to weak alkali, but if it is weakly acidic to acidic, elution of copper ions occurs easily and causes corrosion of the pipe. The resin hose material that may be used in the pipeline of the circulation line 2 and the O-ring rubber material of the connecting joint coupler are likely to be deteriorated when acidic or alkaline. For this reason, it is preferable to use a pH adjuster for the refrigerant. For example, the pH adjuster may be sodium hydroxide (NaOH). The concentration of the pH adjusting agent may be 20 ppm, for example. By using this way the inhibitors and pH adjusting agent for copper, a portion in contact with the coolant C ₀ in copper cooling plate 6 is prevented from eluting by the refrigerant C _0, the deterioration of the hose material and O- ring member Is prevented.

The refrigerant C ₀ warmed by the electronic device 7 enters the heat exchanger 16 provided in the circulation line 2 downstream of the cooling unit 3. In the heat exchanger 16, the refrigerant C ₀ is air-cooled by a fan, the heat of the refrigerant C ₀ is radiated to the outside. A copper material may be used for a portion in contact with the refrigerant C ₀ in the heat exchanger 16. In this case as well, by adding an inhibitor for copper to the refrigerant C ₀ , corrosion of the heat exchanger 16 can be suppressed and water leakage in the heat exchanger 16 can be prevented.

  A tank 18 is provided in the circulation line 2. A sterilizer tank 14 is connected to the tank 18 via a pump 15 and an open / close valve 17. A bactericidal agent is stored in the bactericidal agent tank 14. The bactericide is optional, but may include 5-chloro-2-methyl-4-isothiazolin-3-one and the like. When the open / close valve 17 is in the open state, the sterilizing agent in the sterilizing agent tank 14 is introduced into the tank 18 and supplied into the circulation line 2. At this time, the pump 15 sends the disinfectant in the disinfectant tank 14 to the tank 18. It is also possible to send the sterilizing agent in the sterilizing agent tank 14 to the tank 18 by using gravity, and in this case, the pump 15 may be omitted.

  As shown in FIG. 1, the electronic device cooling system 1 is provided with a biofilm formation sensor 20 for monitoring signs of biofilm formation. The biofilm formation sensor 20 includes a copper electrode portion 21 and a reference electrode 28. Reference electrode 28 may be, for example, a silver / silver chloride / saturated potassium chloride electrode. The biofilm formation sensor 20 may include a potentiometer 23. The potentiometer 23 measures a potential difference (natural potential) between the copper electrode portion 21 and the reference electrode 28. The potentiometer 23 may be a separate product from the biofilm formation sensor 20 (may be retrofitted). Details of the structure of the biofilm formation sensor 20 (particularly the structure of the copper electrode portion 21) will be described later.

  The biofilm formation sensor 20 may be provided at any location in the circulation line 2. However, preferably, the biofilm formation sensor 20 is provided at a location where the flow rate in the circulation line 2 is low. In the example shown in FIG. 1, the biofilm formation sensor 20 is provided in the piping part 2 a in the circulation line 2. As schematically shown in FIG. 1, the pipe part 2 a may be a part having a larger diameter than other pipe parts.

  The electronic device cooling system 1 includes a controller 30 as shown in FIG. The controller 30 may be formed by a computer, for example. The potentiometer 23 and the open / close valve 17 are connected to the controller 30. The controller 30 opens and closes the open / close valve 17 based on the potential difference from the potentiometer 23. For example, the controller 30 opens the opening / closing valve 17 (and drives the pump 15) when the potential difference from the potentiometer 23 exceeds a predetermined threshold, and the sterilizing agent is transferred from the sterilizing agent tank 14 into the circulation line 2. And supply. The supply amount of the sterilizing agent may be adjusted by opening / closing control of the opening / closing valve 17.

  In the case of a general refrigerant, the predetermined threshold is preferably set to a range of 100 to 200 mV (saturated silver / silver chloride electrode standard), and the threshold is preferably set to 180 mV to 190 mV. This is because the pitting corrosion potential of the copper tube is 194 mV with respect to the reference electrode 28, and if this value is exceeded, corrosion tends to occur. The controller 30 may close the open / close valve 17 and stop the supply of the bactericidal agent when the potential difference from the potentiometer 23 becomes less than a predetermined threshold value.

  The configuration of the electronic device cooling system 1 shown in FIG. 1 is merely an example, and various changes can be made. For example, the biofilm formation sensor 20 is disposed in the front stage of the electronic device 7, but may be disposed in the rear stage of the electronic device 7. A plurality of biofilm formation sensors 20 may be arranged in the circulation line 2. Further, the positions of the circulation pump 13 and the tank 18 are arbitrary, and may be arranged at a position other than the position shown in FIG.

  FIG. 2 is a cross-sectional view showing an example of an arrangement state of the biofilm formation sensor 20. In FIG. 2, the flow of the refrigerant is schematically shown by arrows P and P1.

  The copper electrode part 21 and the reference electrode 28 of the biofilm formation sensor 20 may be disposed so as to face each other in the flow direction, as shown in FIG. Further, the copper electrode portion 21 may be disposed upstream of the reference electrode 28 in the flow direction. The copper electrode portion 21 and the reference electrode 28 may be connected to the potentiometer 23 by a lead wire 23a such as an enameled wire (covered copper wire) as shown in FIG.

  As shown in FIG. 2, the copper electrode portion 21 includes a copper plate 210 that forms a copper electrode (an example of a metal electrode) and a cover portion 220.

  The copper plate 210 may have a flat plate shape. The copper plate 210 is preferably arranged so that the direction perpendicular to the plane (the normal direction of the flat plate) is parallel to the flow direction.

  The cover part 220 covers the upstream surface 210 a in the flow direction of the copper plate 210. At this time, the cover 220 preferably covers the entire upstream surface 210 a of the copper plate 210. Thereby, since the copper plate 210 is not exposed in the flow direction of the refrigerant, the refrigerant having a high flow velocity is prevented from hitting the copper plate 210. Therefore, the copper plate 210 is exposed on the downstream side where the flow velocity is low, and stable sensing is possible in an environment where a biofilm is easily formed. In other words, the surface 210b on the downstream side of the copper plate 210 is exposed from the copper plate 210, and stable sensing is possible in an environment with a small flow rate suitable as a living environment for microorganisms.

  In the example shown in FIG. 2, the cover part 220 has a laminated structure, and from the upstream side, the first resin plate 222, the first rubber member 224, the second rubber member 226, the third rubber member 228, Second resin plate 230. The third rubber member 228 and the second resin plate 230 are formed with an opening (window) 70 at the center. The copper plate 210 is fitted into the center portion of the third rubber member 228. As a result, the side surface of the copper plate 210 is covered, and only the surface 210 b on the downstream side of the copper plate 210 is exposed to the coolant through the opening 70. Since the flow rate of the refrigerant in the opening 70 becomes substantially zero (because it becomes a refrigerant retention part), sensing in an environment where a biofilm is easily formed becomes possible.

  As described above, according to the present embodiment, by using the copper electrode portion 21 including the cover portion 220, it is possible to perform sensing by forming a refrigerant retention portion in a simulated manner. Thereby, the natural potential corresponding to the place where the biofilm is most likely to be formed in the entire piping system (the place where the refrigerant is likely to stay) can be monitored. As a result, it is possible to detect signs of biofilm formation at an early stage and administer the bactericidal agent to prevent corrosion deterioration of the metal piping.

  On the downstream side of the copper electrode portion 21, as indicated by an arrow P <b> 2, the flow (rear flow) is disturbed by the edge portion of the copper electrode portion 21, and a component (convection component) toward the upstream side can be generated. In this regard, in the example shown in FIG. 2, since only the central portion of the surface 210b on the downstream side of the copper plate 210 is exposed (because the outer peripheral portion is covered), the influence of such convection can be reduced.

  FIG. 3 is a view showing an example of the configuration of the copper electrode portion 21 (first embodiment), (A) is a top view seen from the downstream side, and (B) is a top view seen from the upstream side. (C) is a sectional view along line AA in (A).

  The copper electrode portion 21 shown in FIG. 3 has substantially the same configuration as the copper electrode portion 21 shown in FIG. However, as shown in FIG. 3, the copper electrode portion 21 shown in FIG. 3 has a depth of holes formed by the openings 70 (that is, the thickness of the third rubber member 228 and the second resin plate 230). 2 is larger than the copper electrode portion 21 shown in FIG. The greater the depth of the hole formed by the opening 70, the closer the flow rate of the coolant in contact with the downstream surface 210b of the copper plate 210 is to zero. The closer the flow rate of the refrigerant in contact with the surface 210b on the downstream side of the copper plate 210 is closer to zero, the easier it is to form a biofilm. Therefore, the depth of the hole formed by the opening 70 may be set so that the flow rate of the refrigerant hitting the surface 210b on the downstream side of the copper plate 210 is substantially zero. Alternatively, the depth of the hole formed by the opening 70 may be adjusted (adapted) in accordance with the flow velocity at the position where the biofilm is most easily formed in the circulation line 2. That is, assuming that the flow velocity at the portion where the biofilm is most easily formed in the entire circulation line 2 is Vo, the depth of the hole formed by the opening 70 is determined by the flow velocity of the refrigerant contacting the surface 210b on the downstream side of the copper plate 210 as Vo. It may be set to be. The opening 70 where the copper plate 210 is in contact with the refrigerant only needs to have a size of about 2 mm × 2 mm, and the second resin plate 230 with the opening 70 may have a size of about 7 mm × 5 mm. The third rubber member 228 may have a thickness of about 10 to 20 mm.

  FIG. 4 is an exploded view showing an example of the copper electrode portion 21. As shown in FIG. 4, the copper electrode portion 21 includes a first resin plate 222, a first rubber member 224, a second rubber member 226 in which the copper plate 210 is fitted in the center portion, a third rubber member 228, The second resin plate 230 may be laminated. Each member, such as between the first resin plate 222 and the first rubber member 224, may be closely coupled with an adhesive or the like. The second rubber member 226 may be penetrated by the lead wire 23a. The lead wire 23a may be coupled to the copper plate 210 by welding or the like.

  In addition, the specific structure of the copper electrode part 21 shown in FIG.3 and FIG.4 is an example to the last, and various changes are possible. For example, any of the first resin plate 222 and the first rubber member 224 may be omitted, and / or any of the third rubber member 228 and the second resin plate 230 may be omitted. Further, the copper electrode portion 21 may be formed by resin molding or the like. That is, the copper electrode portion 21 may be formed by sealing the copper plate 210 with a resin. Moreover, a sealing material etc. may be added.

  FIG. 5 is an image diagram from biofilm formation to biofilm removal in the electronic device cooling system 1, (A) schematically shows a state in which a biofilm is formed, and (B) shows a disinfectant. (C) shows a state in which the biofilm is removed by the bactericidal agent.

  As shown in FIG. 5A, the biofilm includes bacteria, polysaccharides secreted by the bacteria, and the like. When a biofilm starts to be formed, a biofilm also starts to be formed on the copper electrode portion 21. This is because, as described above, the copper electrode portion 21 is formed with a portion (particularly in the opening portion 70) where the biofilm easily adheres. When the biofilm adheres to the copper electrode portion 21, the potential difference (natural potential) measured by the potentiometer 23 increases and exceeds a predetermined threshold value. As a result, as shown in FIG. 5 (B), the bactericide is introduced, and the removal of the biofilm is started. Finally, as shown in FIG. 5 (C), the biofilm is removed. Along with this, the potential difference (natural potential) measured by the potentiometer 23 decreases, and finally returns to a normal value as shown in FIG.

  FIG. 6 is a diagram showing an example of the configuration of the copper electrode portion 21 ′ according to another example (second embodiment), (A) is a top view seen from the downstream side, and (B) is from the upstream side. It is the top view seen, (C) is sectional drawing along line AA in (A).

  6 differs from the copper electrode part 21 according to the first embodiment shown in FIGS. 3 and 4 in the configuration of the first resin plate 222 ′. Specifically, the first resin plate 222 ′ has a quadrangular pyramid shape that is pointed toward the upstream side. Thereby, the turbulence (see arrow P2 in FIG. 2) of the wake of the copper electrode portion 21 is reduced, and the influence of convection can be further reduced.

  Various modifications can be made in the example shown in FIG. For example, the first rubber member 224 may be omitted and / or any of the third rubber member 228 and the second resin plate 230 may be omitted. The first resin plate 222 ′ may be formed of a rubber material. Further, the copper electrode portion 21 ′ may be formed by resin molding or the like. That is, the copper electrode portion 21 may be formed by sealing the copper plate 210 with a resin. The first resin plate 222 ′ may have a truncated quadrangular pyramid shape.

  By the way, generally, in the large-scale water cooling system of an electronic computer, the water quality maintenance management of a refrigerant | coolant is important. The wetted parts of a water-cooled computer are a mixture of metal piping and resin piping.To cool the heat generated by the CPU (central processing unit), a copper cooling plate with high thermal conductivity is used. Copper and stainless steel are often used. In a computer-cooled water cooling system that is not a complete closed circulation system, microorganisms present in the atmosphere are mixed in the refrigerant, the microorganisms propagate in the refrigerant, and a biofilm is formed inside the heat exchanger, resulting in cooling efficiency. There is a problem that decreases. Biofilms attached to metal surfaces are known to cause microbial corrosion. The microbial corrosion caused by the increase of bacteria in the refrigerant has a risk of deteriorating copper piping, SUS (Stainless steel) piping, and resin piping, causing holes to penetrate through the worst piping and leaking refrigerant. Since a water-cooled computer has complicated piping for carrying a refrigerant and is operated on the assumption that it always operates, it is difficult to replace the refrigerant and clean the inside of the pipe.

  In this regard, according to each of the above-described embodiments, a portion where the biofilm is most likely to adhere (retention portion of the refrigerant) in the piping of the circulation cooling system is made by the configuration of the copper electrode portions 21 and 21 ′ ( Mock up). Thereby, since the change of the natural potential by biofilm formation by the retention of a refrigerant | coolant can be measured, the sign which a biofilm adheres to the whole piping system can be detected quickly. Thereby, a sterilant can be discharge | released in the circulation line 2 from the sterilizer tank 14 at an appropriate timing (for example, before corrosion by a biofilm arises), and microbial corrosion can be reduced effectively.

  The present inventor conducted the following tests in order to confirm the effects of the above-described embodiment. Specifically, in order to confirm the effect of the copper electrode portions 21 and 21 ′ for measuring the natural potential at the location simulating the refrigerant retention portion described in the first and second embodiments of the present invention, the flow of the refrigerant is Comparison was made with a comparative example that directly hits a copper electrode. And the effect of the electronic device cooling system 1 was also investigated.

  Corrosion of the copper plate in the circulatory system by measuring the natural potential once a day by the copper electrode portions 21 and 21 'described in the first and second embodiments and introducing a bactericidal agent if necessary. We investigated how much is suppressed. That is, in this investigation, for the sake of convenience, the opening / closing valve 17 is not manually opened / closed by the controller 30, but the opening / closing valve 17 is manually opened / closed.

  In this investigation, the electronic device cooling system 1B according to Comparative Example 1 as shown in FIG. 7 was also examined. In FIG. 7, the same elements as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment. The electronic device cooling system 1B according to the comparative example 1 is different in that the cover part 220 of the copper electrode part 21 in the first embodiment is not present, and the refrigerant flow directly hits the copper plate (electrode part).

  Comparative Example 2 (not shown) has a configuration in which the open / close valve 17 of the sterilizer tank 14 in FIG. 7 is kept closed (that is, a configuration substantially not including the sterilizer tank 14 or the like). Furthermore, in this investigation, the residual inhibitor concentration in the refrigerant, the conductivity of the refrigerant, and the pH of the refrigerant were also examined. The survey results are shown in FIG.

Regarding the corrosion of the copper plate, the entire surface of the test piece (50 mm × 30 mm × 3 mm) made of the copper plate was polished using No. 400 of polishing cloth. Thereafter, the total surface area was calculated from the dimensions of the test piece. Next, the test piece was washed with water, degreased with methanol and acetone, and the weight of the test piece after drying was measured. And the test piece was arrange | positioned under the partition plate 26 provided in the tank 18 of the circulation line 2 (refer FIG. 7). In this way, the part where the refrigerant stays was consciously made. The refrigerant C0 was circulated by the circulation pump 13. As the refrigerant C0, a solution obtained by dissolving benzotriazole in pure water at a concentration of 100 ppm and sodium hydroxide at 20 ppm was used. The amount of water held in the pipe is 100L. 30 L of water containing a soil component containing slime was added. In this case, 30 L of retained water was extracted, and 30 L of dirt component water was added to make the total retained water amount 100 L. The test period was 90 days and 180 days, and the temperature of the refrigerant during the test was 30 ° C. The disinfectant 5-chloro-2-methyl-4-isothiazolin-3-one was dispersed in 1 L of water so as to be 1 wt%, and placed in the disinfectant tank 14. After completion of the test, the corrosion product adhering to the test piece was removed, washed with methanol and acetone, and the weight of the test piece after drying was measured. The degree of erosion in the table was calculated using the degree of corrosion W. Corrosion degree W is the number of mg of corrosion weight loss per day with respect to 1 dm ² of the surface area of the test piece, and its unit is mdd as defined by the following equation.
W = (M1−M2) / (S × T)
The meaning of each parameter in this equation is as follows.
W: Corrosion degree (mdd)
M1: Weight of test specimen before test (mg)
M2: Weight of test specimen after test (mg)
S: surface area of the specimen (dm ² )
T: Number of test days Using this corrosion degree W, the erosion degree P is calculated as follows.
P = W × 365 × 10−4 / d
The meaning of each parameter in the formula is as follows.
P: Degree of erosion (mm / y)
W: Corrosion degree (mdd)
d: Density of test specimen (g / cm ³ )
The erosion degree P defined in this way is the erosion depth per year expressed in mm, and its unit is mm / y. The inhibitor concentration in FIG. 8 was measured with an ultraviolet spectrophotometer (U-1100, manufactured by Hitachi, Ltd.). Further, the conductivity and pH of the refrigerant were measured with a desktop conductivity meter-pH meter (F-55 manufactured by Horiba, Ltd.).

  In the biofilm coating test, a copper plate 27 (see FIG. 7) is immersed in a portion provided with the partition plate 26 in the tank 18, the copper plate 27 is taken out after a predetermined period of time, and the biofilm coating area when the surface is observed. Estimated. Next, the biofilm coverage (= biofilm coverage on the copper plate after removal / total surface area of the copper plate) was determined.

  From the results shown in FIG. 8, in the first and second embodiments, the average value of the copper natural potential is constant regardless of the test period. This is presumably because the water quality was maintained by adding the bactericidal agent when the natural potential of copper was measured in the biofilm detection unit and a potential higher than a predetermined threshold was measured.

  In the first and second embodiments, the biofilm coverage of the copper plate is a low value. In addition, in the first and second embodiments, the refrigerant inhibitor concentration is always about 100 ppm. These results are considered to be due to the addition of the bactericide component in the case of a natural potential higher than the threshold value by measuring the natural potential of copper. Thus, the pH of the refrigerant and the inhibitor concentration can be kept constant, and the corrosion prevention effect of copper by the pH and the inhibitor can be demonstrated over a long period of time, and the erosion degree is 0.005 (mm / y) or less even after 180 days. Very small value.

  On the other hand, in Comparative Example 1, although the natural potential was not so high, the biofilm coverage was high, and the pH and inhibitor concentration were reduced. It can be seen that the potential could not be measured. In Comparative Example 1, the effect of preventing corrosion was not sufficiently exhibited.

  In the comparative example 2, it is a thing of the structure which cannot replenish a disinfectant. The increase in the natural potential of the copper plate and the biofilm coverage increased along with the test period, and the pH and the inhibitor concentration decreased. Therefore, it is considered that the inhibitor component was consumed as the water quality deteriorated. Thus, due to the increase in natural potential, the decrease in pH, and the decrease in inhibitor components, the effect of preventing corrosion was not sufficiently exhibited in Comparative Example 2, and the erosion degree of copper was increased.

  From such investigation results, it is possible to make a potential detection part in the refrigerant retention part as in the first and second embodiments, and to add a bactericide when the natural potential is measured and the threshold value is exceeded. It has been proved that it is effective in preventing corrosion.

  As mentioned above, although each embodiment was explained in full detail, it is not limited to a specific embodiment, A various deformation | transformation and change are possible within the range described in the claim. It is also possible to combine all or a plurality of the constituent elements of the above-described embodiment.

  For example, in the embodiment described above, copper is used as the metal material of the electrode as in the copper electrode portion 21 (the copper electrode portion 21 ′ is the same), but the electrode may be formed of a metal material other than copper. . At this time, a material that can be corroded earliest among materials of a member (a liquid contact member) in contact with the refrigerant may be employed as the electrode material. For example, in a configuration in which copper is not used at all as the material of the liquid contact member and stainless steel is used, stainless steel may be used as the metal material of the electrode. In this case, the predetermined threshold of the determination condition for introducing the bactericide may be set according to the pitting corrosion potential of stainless steel.

  In the above-described embodiment, as shown in FIG. 2, the copper electrode portion 21 (also the copper electrode portion 21 ′ is the same) is arranged near the center (near the center) in the radial direction in the pipe portion 2a. It may be arranged more radially outward. For example, as shown in FIG. 9, the copper electrode part 21 may be arrange | positioned in the aspect in which the edge part of the copper electrode part 21 follows the internal peripheral surface of the piping part 2a. In this case, as shown in FIG. 9, since the flow along the inner peripheral surface of the pipe portion 2a is blocked by the copper electrode portion 21, it stays in the wake of the copper electrode portion 21 on the inner peripheral surface side of the pipe portion 2a. Part is formed. Accordingly, the stay is formed by the inner peripheral surface of the pipe portion 2a, so that the stay portion can be formed more efficiently.

  In the embodiment described above, the biofilm formation sensor 20 is provided in the circulation line 2, but may be provided in a dedicated pipe branched from the circulation line 2. However, according to the above-described embodiment, the retention portion can be formed in the circulation line 2 as described above, and therefore there is no need to provide a dedicated pipe (dedicated pipe for biofilm detection).

  Moreover, in the embodiment described above, as a preferable example, the copper plate 210 in the copper electrode portion 21 (the same applies to the copper electrode portion 21 ′) includes the upstream surface 210 a, the side surface, and a part of the downstream surface 210 b as the cover portion 220. Covered by. However, only the upstream surface 210 a of the copper electrode portion 21 may be covered by the cover portion 220, or only the upstream surface 210 a and the side surface may be covered by the cover portion 220. Also in this case, since the surface 210a on the upstream side of the copper plate 210 is covered with the cover portion 220, sensing at a location where the flow velocity is relatively low by the surface 210b on the downstream side of the copper plate 210 is still possible.

  Moreover, in the embodiment mentioned above, the reference electrode 28 is arrange | positioned in the aspect which opposes the copper plate 210 in the flow direction in the downstream rather than the copper electrode part 21 (the copper electrode part 21 'is the same) in the flow direction. However, the reference electrode 28 does not necessarily have to be disposed downstream of the copper electrode portion 21 in the flow direction, and does not necessarily have to face the copper plate 210 in the flow direction.

In addition, the following additional remarks are disclosed regarding the above embodiment.
(Appendix 1)
A metal electrode disposed in the flow path;
A reference electrode disposed in the flow path;
A biofilm formation sensor comprising: a cover portion that is formed of a non-metallic material and covers an upstream surface in the flow direction of the metal electrode in the flow path.
(Appendix 2)
The biofilm formation sensor according to appendix 1, wherein the metal electrode has a flat plate shape and is arranged so that a perpendicular direction is parallel to a flow direction in the flow path.
(Appendix 3)
The biofilm formation sensor according to appendix 1 or 2, wherein the cover portion further covers a side surface of the metal electrode and an outer peripheral portion of a surface on the downstream side in the flow direction of the metal electrode in the flow path.
(Appendix 4)
The biofilm formation sensor according to any one of appendices 1 to 3, further including a potentiometer that measures a potential between the metal electrode and the reference electrode.
(Appendix 5)
The bio according to any one of appendices 1 to 4, wherein the reference electrode is disposed downstream of the metal electrode in the flow direction in the flow path and faces the metal electrode in the flow direction. Film formation sensor.
(Appendix 6)
A flow path through which a refrigerant for cooling an electronic device flows;
A metal electrode disposed in the flow channel in the flow channel;
A reference electrode disposed in the flow path;
A cover part that is formed of a non-metallic material and covers an upstream surface in the flow direction of the metal electrode in the flow path;
A disinfectant tank for storing disinfectant,
A valve provided between the disinfectant tank and the flow path;
An electronic device cooling system comprising: a control device that opens the valve and introduces the sterilizing agent from the sterilizing agent tank into the flow path when a potential difference between the metal electrode and the reference electrode becomes a predetermined threshold value or more. .

DESCRIPTION OF SYMBOLS 1 Electronic device cooling system 2 Circulation line 2a Piping part 3 Cooling part 4 Manifold 5 Rubber tube 6 Cooling plate 7 Electronic device 8 Copper piping 13 Circulation pump 14 Disinfectant tank 15 Pump 16 Heat exchanger 17 Opening and closing valve 18 Tank 20 Biofilm formation Sensor 21, 21 ′ Copper electrode part 23 Potentiometer 23 a Lead wire 28 Reference electrode 30 Controller 70 Opening part 210 Copper plate 210 a, 210 b Surface 220 Cover part 222, 222 ′ First resin plate 224 First rubber member 226 Second rubber member 228 Third rubber member 230 Second resin plate

Claims (4)

A metal electrode disposed in the flow path;
A reference electrode disposed in the flow path;
A biofilm formation sensor comprising: a cover portion that is formed of a non-metallic material and covers an upstream surface in the flow direction of the metal electrode in the flow path.   The biofilm forming sensor according to claim 1, wherein the metal electrode has a flat plate shape and is arranged so that a perpendicular direction is parallel to a flow direction in the flow path.   The biofilm formation sensor according to claim 1 or 2, wherein the cover portion further covers a side surface of the metal electrode and an outer peripheral portion of a downstream surface of the metal electrode in a flow direction in the flow path. A flow path through which a refrigerant for cooling an electronic device flows;
A metal electrode is placed in the flow channel,
A reference electrode disposed in the flow path;
A cover part that is formed of a non-metallic material and covers an upstream surface in the flow direction of the metal electrode in the flow path;
A disinfectant tank for storing disinfectant,
A valve provided between the disinfectant tank and the flow path;
An electronic device cooling system comprising: a control device that opens the valve and introduces the sterilizing agent from the sterilizing agent tank into the flow path when a potential difference between the metal electrode and the reference electrode becomes a predetermined threshold value or more. .

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