JP2017053528A - Heat storage device and overcooling release device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat storage device with high reliability.SOLUTION: A heat storage device according to one embodiment includes: a heat storage tank; a heat storage material stored in the heat storage tank and enabling overcooling; an anode electrode immersed into the heat storage material; a cathode electrode immersed into the heat storage material at a position separate from the anode electrode; an electric supply unit applying voltage between the anode electrode and the cathode electrode; a plurality of groove parts provided on a surface of the anode electrode; and a nucleation start part provided between the plurality of grooves. Surface roughness Ra of the groove part in the anode electrode is within a range of 0.05-4.0 μm.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a heat storage device capable of accumulating or releasing heat and a supercooling release device used therefor.

  There is known a heat storage device that uses supercooling of a heat storage material capable of phase change. This heat storage device stores heat in a supercooled state in this heat storage material, and when a heat release request is made, releases the supercooling state and changes the phase of the heat storage material from a liquid to a solid, and the latent heat released along with it. Is used.

  Canceling the supercooled state of the heat storage material that has been supercooled and in the liquid phase state to change the phase of the heat storage material from a liquid to a solid is called “nucleation”. When the nucleation operation is performed while the heat storage material is in the liquid phase, crystal nuclei are formed in the heat storage material that is supercooled and in the liquid phase, and crystallization starts from that.

JP 2012-32130 A JP 2014-102014 A Japanese Patent Laying-Open No. 2015-83882

  In recent years, there has been a demand for a heat storage device from the viewpoint of efficient use of energy, and a highly reliable heat storage device has been demanded.

  The heat storage device of the embodiment includes a heat storage tank, a heat storage material accommodated in the heat storage tank and capable of being supercooled, an anode electrode immersed in the heat storage material, and a cathode immersed in the heat storage material at a position separated from the anode electrode An electrode, a power supply unit for applying a voltage between the anode electrode and the cathode electrode, a plurality of groove portions provided on the surface of the anode electrode, and a nucleation starting point portion provided between the plurality of groove portions The surface roughness Ra of the anode electrode is 0.05 μm or more and 4.0 μm or less.

Drawing 1 is a mimetic diagram showing the heat storage device and supercooling release device of an embodiment. FIG. 2 is a schematic diagram showing the surface processing state of the anode electrode of the heat storage device and the supercooling release device shown in FIG. FIG. 3 is a table showing the nucleation waiting time, supercooling holding time, and anode electrode processing method of Examples 1 to 17 and Comparative Examples 1 to 6 in the heat storage device and the supercooling release device of the embodiment. FIG. 4 is an electron micrograph showing the surface of the anode electrode of Example 4 shown in FIG. FIG. 5 is an electron micrograph showing the surface of the anode electrode of Example 7 shown in FIG. FIG. 6 is a graph in which the height of the unevenness is measured with a surface roughness measuring instrument for a part of the surface of the anode electrode of Example 4 shown in FIG. FIG. 7 is a graph in which the height of the unevenness is measured with a surface roughness measuring instrument for a part of the surface of the anode electrode of Example 7 shown in FIG.

  Hereinafter, a heat storage device according to an embodiment of the present invention will be described in detail with reference to FIGS. In recent years, there has been a demand for a heat storage device from the viewpoint of efficient use of energy, and a highly reliable heat storage device has been demanded. Applications for heat storage devices include use of solar heat during the day as hot water at night, start-up assistance for air conditioning heating, use for engine warm-up and heating assistance for automobile winter, heat transport use, and unsteady heat Use application etc. are mentioned.

  As shown in FIG. 1, the heat storage device 1 includes a heat storage unit 2 and a control unit 8. The control unit 8 includes a power supply unit 9 and a control circuit 10. The control unit 8 forms a unit, for example, and is provided on the outside (outer surface) of the heat storage tank 3, for example. The control unit 8 may be provided separately from the heat storage tank 3. The control unit 8 may be connected to or incorporated in, for example, an air conditioner control system including the heat storage device 1. Furthermore, the control unit 8 may be connected to or incorporated in another system including the heat storage device 1 such as a network home appliance control system that controls the entire air conditioner and other home appliances.

  The positive electrode of the power supply unit 9 is connected to the anode electrode 5 described later via the first power supply line 11. The negative electrode of the power supply unit 9 is connected to the cathode electrode 6 to be described later via the second feeder line 12. That is, the power supply unit 9 can apply a voltage between the anode electrode 5 and the cathode electrode 6.

  The power supply unit 9 includes, for example, a plurality of batteries and a switch circuit. The switch circuit can electrically connect the anode electrode 5 and the cathode electrode 6 and the battery, and can interrupt the electrical connection state of the anode electrode 5 and the cathode electrode 6 and the battery. The power supply unit 9 can set the voltage applied between the anode electrode 5 and the cathode electrode 6 to an arbitrary value by switching the connection state of a plurality of batteries with a switch circuit. The power supply unit 9 may be a constant voltage power supply that can set the voltage applied between the anode electrode 5 and the cathode electrode 6 to an arbitrary value.

  The control circuit 10 includes a memory, a calculation unit, an applied voltage controller, and the like. Various data necessary for controlling the heat storage device 1 are stored in the memory of the control circuit 10. The applied voltage controller of the control circuit 10 and the power supply unit 9 are electrically connected via a signal line 13.

  The heat storage unit 2 includes a heat storage tank 3, a heat storage material 4, an anode electrode 5, and a cathode electrode 6.

  The heat storage material 4 is accommodated in the heat storage tank 3. As the heat storage material 4, a latent heat storage material (PCM; Phase change material) having supercooling performance is used. The heat storage material 4 has a characteristic of maintaining the liquid phase state without solidifying even when the temperature is lowered from the liquid phase state to be below the melting point. Such a heat storage material 4 is referred to as a latent heat storage material or a phase change heat storage material having supercooling performance.

  As the heat storage material 4, for example, sodium acetate such as sodium acetate trihydrate or sodium sulfate such as sodium sulfate hydrate can be used. When the heat storage temperature is high, it is desirable to use sodium acetate trihydrate as the heat storage material 4. General physical properties of sodium acetate trihydrate are a melting point of 40 to 58 ° C., a latent heat of 100 to 264 kj / kg, and a specific heat of 1 to 4 kJ / kg / K.

  The cathode electrode 6 is formed of a conductive metal material such as stainless steel, titanium, silver, or the like, and can apply a negative voltage to the heat storage material 4. More specifically, the cathode electrode 6 is made of a metal mainly composed of silver, such as silver or a silver alloy. As shown in FIG. 1, the cathode electrode 6 is provided separately from the anode electrode 5, and is arranged in a state where a part or all of the cathode electrode 6 is immersed in the heat storage material 4. The cathode electrode 6 has, for example, a round bar shape.

  As shown in FIG. 1, the anode electrode 5 is arranged in a state where a part or the whole is immersed in the heat storage material 4. Similarly, the groove 7 formed in the anode electrode 5 is immersed in the heat storage material 4.

  The anode electrode 5 has, for example, a round bar shape. The anode electrode 5 is formed of a conductive metal material, and can apply a positive voltage to the heat storage material 4. Suitable materials for the anode electrode 5 include silver, copper, copper amalgam and the like. More specifically, the anode electrode 5 is made of a metal mainly composed of silver, such as silver or a silver alloy. As shown in the schematic diagram of FIG. 2, the surface of the anode electrode 5 is formed at a position sandwiched between a plurality of linear groove portions 7 formed at different angles and a pair of intersecting groove portions 7. And a plurality of corners. The groove part 7 (the inner surface of the groove part 7) is a part that easily elutes metal ions as compared with other parts of the anode electrode 5, and constitutes a so-called nucleation starting point part. That is, when a voltage is applied between the anode electrode 5 and the cathode electrode 6, the metal ions eluted from the groove 7 serve as a starting point for crystallizing (nucleating) the supercooled heat storage material 4.

  On the other hand, in this embodiment, in addition to the heat storage device 1 described above, the inventive concept of a supercooling release device is realized. As shown in FIG. 1, the supercooling release device 14 is configured to include a part of the components of the heat storage device 1 described above. The supercooling release device 14 includes a control unit 8 and an electrode unit 17. The control unit 8 includes the power supply unit 9 described above, the control circuit 10 described above, and the signal line 13 described above. The electrode portion 17 includes the anode electrode 5 in which the groove portion 7 is formed, the cathode electrode 6 described above, the first power supply line 11 described above, and the second power supply line 12 described above. The supercooling release device 14 is used by inserting the anode electrode 5 and the cathode electrode 6 into a heat storage material such as the above-described heat storage material 4 in a supercooled state. In this state, the supercooling release device 14 can release the supercooling state of the heat storage material by applying a voltage to the heat storage material, and can extract heat from the heat storage material.

  Then, the effect | action of the thermal storage apparatus 1 and the supercooling cancellation | release apparatus 14 of this embodiment is demonstrated.

  Prior to use, the heat storage material 4 in the heat storage tank 3 is heated in advance to a temperature equal to or higher than the melting point (heat input). As a result, the heat storage material 4 is dissolved to be in a liquid phase. In addition, since the heat storage material 4 is a latent heat storage material that can be supercooled, even if the heat storage material 4 falls below the melting point after completion of heat input, it maintains a liquid phase state without solidifying (becomes a supercooled state). ). In this state, the heat storage material 4 continues to store latent heat.

  When the heat storage material 4 is kept in a supercooled state, the control circuit 10 performs control so that no voltage is applied between both electrodes (the anode electrode 5 and the cathode electrode 6). While the heat storage material 4 is maintained in the supercooled state by this control, the heat storage material 4 is stable in the supercooled liquid phase state, and the heat storage material 4 is not crystallized (nucleated). For this reason, the latent heat stored in the heat storage material 4 is not released.

  When a command for taking out the latent heat of the heat storage material 4 is given to the control circuit 10 from the outside, the control circuit 10 controls the power supply unit 9 to apply a predetermined voltage between both electrodes. At this time, a predetermined voltage may be continuously applied between the electrodes for a certain period of time, or the predetermined voltage may be applied in a pulsed manner divided into a plurality of times.

  When a predetermined voltage is applied between the anode electrode 5 and the cathode electrode 6, an oxidation reaction of the metal constituting the anode electrode 5 occurs on the surface of the groove 7 (nucleation start point), and water is reduced on the cathode electrode 6 side. A reaction occurs and a current flows through the heat storage material 4. As the voltage applied between the electrodes by the power supply unit 9 increases, metal ions are eluted from the anode electrode 5 by the oxidation reaction.

  As a result, the heat storage material 4 in the liquid phase is crystallized and the supercooled state is released. When nucleation occurs, the supercooled heat storage material 4 undergoes a phase displacement from the liquid phase state to the solid phase state, thereby releasing latent heat. The released latent heat is used as thermal energy.

  In addition, it is preferable that the voltage applied between both electrodes uses the minimum voltage which can cancel | release the supercooling of the thermal storage material 4 in a liquid phase state (nucleating the thermal storage material 4). When using silver as the anode electrode 5, the inventors prefer that the voltage applied between both electrodes is preferably 1.0 V or more and 2.0 V or less, and that the voltage applied between both electrodes is 1.5 V. It has been found that the 1.9 V or less is more preferable in terms of enhancing the nucleation responsiveness and nucleation lifetime characteristics of the heat storage material 4.

  Subsequently, Examples 1 to 17 and Comparative Examples 1 to 6 in which conditions (depth of the groove 7, that is, surface roughness Ra) of the anode electrode 5 are changed will be described. The table of FIG. 3 shows the conditions of each example and each comparative example.

  The surface roughness (arithmetic average roughness) Ra of the anode electrode 5 of each example was measured in a temperature-controlled room at 21 ° C. and 40% using a surface roughness measuring instrument (for example, Foam Talysurf PGI820). The surface roughness (arithmetic average roughness) Ra value (JIS B 0031) (JIS B 0601) is determined by extracting only the reference length from the roughness curve in the direction of the average line, and X in the direction of the average line of the extracted portion. The axis is defined as a value obtained from an equation when the Y axis is taken in the direction of the vertical magnification and the roughness curve is represented by an integral equation. In the following examples and comparative examples, irregularities were formed in the silver rod used as the anode electrode 5 in the range of the surface roughness Ra value of 0.01 to 100 μm.

  Nucleation responsiveness was evaluated by measuring nucleation waiting time. The nucleation waiting time is measured by applying a constant voltage of 1.7 V in a step waveform between the anode electrode 5 and the cathode electrode 6 and measuring the time from the start of application until the crystallization of the heat storage material 4 starts. Asked. And in each Example, the nucleation waiting time of the first 1st cycle (initial stage) and the nucleation waiting time after performing nucleation 1000 times were measured. The supercooling holding time was maintained by heating the heat storage material 4 in the heat storage device 1 to melt it, then returning to normal temperature, and continuing how many hours the supercooled state was maintained without spontaneous nucleation. The nucleation responsiveness and the supercooling holding time were tested for 10 samples for each example, and the average value was used as the measurement result.

  In Example 1, the surface of a silver round bar having a diameter of 2 mm was polished with sand paper of # 30 to form a plurality of groove portions 7 (nucleation start point portions), and the anode electrode 5 was created. The surface roughness Ra of the surface of the anode electrode 5 was 4 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 1 second and the nucleation response (reliability) was good. The supercooling holding time was 16 hours.

  In Example 2, the surface of a silver round bar having a diameter of 2 mm was polished with # 40 sandpaper to form a plurality of groove portions 7 (nucleation start point portions), and thus the anode electrode 5 was formed. The surface roughness Ra of the surface of the anode electrode 5 was 3 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was 51 hours.

  In Example 3, in Example 1, the surface of a silver round bar having a diameter of 2 mm was polished with # 50 sand paper to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. did. The surface roughness Ra of the surface of the anode electrode 5 was 2 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was 73 hours.

  In Example 4, the surface of a silver round bar having a diameter of 2 mm was polished with # 80 sand paper to form a plurality of groove portions 7 (nucleation start point portions), and thus an anode electrode 5 was formed. The surface roughness Ra of the surface of the anode electrode 5 was 1.6 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In FIG. 4, the electron micrograph which shows the state of the surface of the anode electrode 5 of Example 4 is shown. FIG. 6 shows the measurement results of the height (roughness) from the average line of the surface of the anode electrode 5 of Example 4. 4 and 6 (particularly FIG. 6), in Example 4, it can be confirmed that the surface of the anode electrode 5 actually has a surface roughness of about Ra = 1.6 μm.

  In Example 5, the surface of a silver round bar having a diameter of 2 mm was polished with sandpaper of # 600 to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. The surface roughness Ra of the surface of the anode electrode 5 was 0.8 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 3 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 6, the surface of a silver round bar with a diameter of 2 mm was polished with # 1200 sand paper to form a plurality of groove portions 7 (nucleation start point portions), and the anode electrode 5 was created. The surface roughness Ra of the surface of the anode electrode 5 was 0.2 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 5 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 7, the surface of a silver round bar having a diameter of 2 mm was polished with # 2000 sand paper to form a plurality of groove portions 7 (nucleation start point portions), and thus the anode electrode 5 was formed. The surface roughness Ra of the surface of the anode electrode 5 was 0.1 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 7 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In FIG. 5, the electron micrograph which shows the state of the surface of the anode electrode 5 of Example 7 is shown. FIG. 7 shows the measurement results of the height (roughness) from the average line on the surface of the anode electrode 5 of Example 7. 5 and 7 (particularly FIG. 7), in Example 7, it can be confirmed that the surface of the anode electrode 5 actually has a surface roughness of about Ra = 0.1 μm.

  In Example 8, the surface of a silver round bar with a diameter of 2 mm was polished with # 2500 sand paper to form a plurality of groove portions 7 (nucleation starting point portions), and the anode electrode 5 was formed. The surface roughness Ra of the surface of the anode electrode 5 was 0.05 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 10 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 9, the anode electrode 5 was created by performing sand blasting as a dry etching technique on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). In sandblasting, fine abrasive grains (projection material) are jetted onto a workpiece at high speed using compressed air, and fine processing is performed according to the brittle fracture principle. In the sandblasting process, a sandblasting apparatus was used, and glass beads of about 50 μm were used as the projection material. A fixed amount of the projection material was supplied, the injection amount was 30 g / min, the pressure was 0.8 MPa, and the injection time was 5 minutes. The surface roughness Ra of the surface of the anode electrode 5 subjected to sandblasting was 1.0 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 10, the anode electrode 5 was formed by performing sandblasting on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). In the sandblasting process, a sandblasting apparatus was used, and glass beads of about 20 μm were used as the projection material. A fixed amount of the projection material was supplied, the injection amount was 30 g / min, the pressure was 0.8 MPa, and the injection time was 5 minutes. The surface roughness Ra of the surface of the anode electrode 5 subjected to sandblasting was 0.1 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 7 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 11, the anode electrode 5 was created by performing sandblasting on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). In the sandblasting process, a sandblasting apparatus was used, and glass beads of about 70 μm were used as the projecting material. A fixed amount of the projection material was supplied, the injection amount was 30 g / min, the pressure was 0.8 MPa, and the injection time was 5 minutes. The surface roughness Ra of the surface of the anode electrode 5 subjected to sandblasting was 1.6 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 12, a chemical etching process was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. Known chemicals (for example, nitric acid, sulfuric acid, etc.) can be used for the chemical etching treatment. The surface roughness Ra of the surface of the anode electrode 5 subjected to the chemical etching treatment was 1.0 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 13, a chemical etching process was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. Known chemicals (for example, nitric acid, sulfuric acid, etc.) can be used for the chemical etching treatment. The surface roughness Ra of the surface of the anode electrode 5 subjected to the chemical etching treatment was 1.0 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 14, a chemical etching treatment was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. Known chemicals (for example, nitric acid, sulfuric acid, etc.) can be used for the chemical etching treatment. The surface roughness Ra of the surface of the anode electrode 5 subjected to the chemical etching treatment was 1.6 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 15, laser processing was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), and the anode electrode 5 was formed. For example, a laser marking device used for product printing or the like is used for laser processing. However, a laser fine processing device used for a semiconductor manufacturing process or the like, or a general laser processing machine can also be used. The surface roughness Ra of the surface of the anode electrode 5 subjected to laser processing was 1.0 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 16, laser processing was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), and the anode electrode 5 was formed. For example, a laser marking device used for product printing or the like was used for laser processing. The surface roughness Ra of the surface of the anode electrode 5 subjected to laser processing was 0.1 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 7 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Example 17, laser processing was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation starting point portions), and thus the anode electrode 5 was formed. For example, a laser marking device used for product printing or the like was used for laser processing. The surface roughness Ra of the surface of the anode electrode 5 subjected to laser processing was 1.6 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the nucleation waiting time was 2 seconds, and the nucleation response (reliability) was good. The supercooling holding time was one week (168 hours or more).

  In Comparative Example 1, the anode electrode 5 was formed by brushing the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). As an example, the brushing process uses a SK channel brush made of stainless steel or iron and having different brush inner diameter standards, but a general brush processing machine can also be used. The surface roughness Ra of the surface of the brushed anode electrode 5 was 5 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the waiting time for nucleation was 1 second. The supercooling holding time was 5 hours.

  In Comparative Example 2, the anode electrode 5 was created by brushing the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). The surface roughness Ra of the surface of the brushed anode electrode 5 was 10 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the waiting time for nucleation was 1 second. The supercooling holding time was shorter than 1 hour.

  In Comparative Example 3, embossing was performed on the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions), thereby creating an anode electrode 5. For example, double-sided embossing or single-sided embossing using a metal embossing roll was used for embossing. An embossing machine equipped with an embossing roll other than metal can also be used. The surface roughness Ra of the surface of the embossed anode electrode 5 was 50 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the waiting time for nucleation was 1 second. The supercooling holding time was shorter than 1 hour.

  In Comparative Example 4, the anode electrode 5 was formed by drilling the surface of a silver round bar having a diameter of 2 mm to form a plurality of groove portions 7 (nucleation start point portions). The drilling was performed by cutting similar to the embodiment described in Japanese Patent Application Laid-Open No. 2015-83882. The surface roughness Ra of the drilled anode electrode 5 surface was 100 μm. The initial nucleation waiting time was less than 1 second, and nucleation occurred almost simultaneously with the voltage application. Even after 1000 cycles, the waiting time for nucleation was 1 second. The supercooling holding time was shorter than 1 hour.

  In Comparative Example 5, the anode electrode 5 is formed by polishing a surface of a silver round bar having a diameter of 2 mm with copy paper (or general paper) to form a plurality of groove portions 7 (nucleation start point portions). did. The surface roughness Ra of the surface of the polished anode electrode 5 was 0.03 μm. The initial nucleation waiting time was 64 seconds, and the responsiveness of nucleation was poor. Even after 1000 cycles, the nucleation waiting time was 131 seconds, and the nucleation response was further deteriorated. From the experimental results of Comparative Example 5, it was found that when the Ra value is smaller than 0.05 μm, the nucleation responsiveness at the initial stage and after 1000 cycles becomes extremely poor. The supercooling holding time was one week (168 hours or more).

  In Comparative Example 6, a silver round bar having a diameter of 2 mm was used as the anode electrode 5 as it was without performing surface treatment. The surface roughness Ra of the anode electrode 5 surface was 0.01 μm. The initial nucleation waiting time was 118 seconds, and the responsiveness of nucleation was poor. Even after 1000 cycles, the nucleation waiting time was 287 seconds, and the nucleation response was further deteriorated. The supercooling holding time was one week (168 hours or more).

  According to the present embodiment, the heat storage device 1 is separated from the heat storage tank 3, the heat storage material 4 accommodated in the heat storage tank 3 and capable of being supercooled, the anode electrode 5 immersed in the heat storage material 4, and the anode electrode 5. A cathode electrode 6 immersed in the heat storage material 4 at a position; a power supply unit 9 for applying a voltage between the anode electrode 5 and the cathode electrode 6; and a plurality of grooves 7 provided on the surface of the anode electrode 5. The surface roughness Ra of the groove 7 of the anode electrode 5 is 0.05 μm or more and 4.0 μm or less.

  According to the embodiment, the supercooling release device 14 applies a voltage between the anode electrode 5, the cathode electrode 6 provided at a position separated from the anode electrode 5, and the anode electrode 5 and the cathode electrode 6. Power supply unit 9 and a plurality of grooves 7 provided on the surface of the anode electrode 5, and the surface roughness Ra of the grooves 7 of the anode electrode 5 is 0.05 μm or more and 4.0 μm or less.

  In general, when a metal is used for the nucleation electrode, metal ions eluted from the anode electrode 5 by voltage application form a diffusion double layer on the electrode surface, and the electric field generated there becomes a driving force for nucleation. Therefore, elution of the electrode is essential for voltage nucleation, and repeating the nucleation operation results in thinning of the metal electrode and loss of the nucleation function.

  Said structure respond | corresponds to above-mentioned Examples 1-17. According to the above configuration, the initial nucleation waiting time can be shortened to less than 1 second. Moreover, even if the surface of the anode electrode 5 is thinned by voltage application of a plurality of cycles, the nucleation response can be improved by setting the surface roughness Ra within the above range. For this reason, the nucleation waiting time after 1000 cycles can be reduced to 10 seconds or less. As a result, a practically no problem level can be obtained, and the life of the nucleation cycle can be extended. From the above, it is possible to provide a highly reliable heat storage device 1 (supercooling release device 14) that has a short nucleation waiting time and that has a high durability against repeated nucleation operations.

  According to the above configuration, the supercooled state can be maintained for 16 hours or longer. Thereby, for example, a heat storage device can be used for the purpose of using solar heat during the daytime as hot water, which can contribute to energy saving in ordinary homes, commercial facilities, factories, and the like.

  In this case, the surface roughness Ra of the groove 7 of the anode electrode 5 is preferably 0.05 μm or more and 3.0 μm or less. This configuration corresponds to Examples 2 to 17 described above. According to this configuration, the initial nucleation waiting time can be made less than 1 second. Also, the nucleation waiting time after 1000 cycles can be set to 10 seconds or less, which is a level that is not problematic in practice. In addition, the supercooled state can be maintained for 1 day or longer (51 hours or longer). As a result, the applications can be further expanded from the above-mentioned claims, and can be used not only for the applications corresponding to the above-mentioned claims but also for, for example, engine warm-up and heating assist in automobiles. This can contribute to energy saving of automobiles.

  In this case, the surface roughness Ra of the groove portion 7 of the anode electrode 5 is preferably 0.05 μm or more and 1.6 μm or less. This configuration corresponds to Examples 4 to 17 described above. According to this configuration, the initial nucleation waiting time can be made less than 1 second. Also, the nucleation waiting time after 1000 cycles can be set to 10 seconds or less, which is a level that is not problematic in practice. In addition, the supercooled state can be maintained for one week or longer (168 hours or longer), and long-term heat storage performance can be improved. As a result, the applications are further expanded from the above-mentioned claims, and not only for applications corresponding to the above-mentioned claims but also for applications that require a long time to use heat, such as heat transport applications and unsteady heat utilization applications. Can also be used.

  The anode electrode 5 and the cathode electrode 6 are made of a metal mainly composed of silver. According to this configuration, by using silver that has already been proven as the anode electrode 5 and the cathode electrode 6 of the heat storage device 1, the heat storage material 4 in a supercooled state can be stably nucleated. Thereby, the reliability of the heat storage device can be improved.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Thermal storage apparatus, 2 ... Thermal storage part, 3 ... Thermal storage tank, 4 ... Thermal storage material, 5 ... Anode electrode, 6 ... Cathode electrode, 7 ... Groove part, 8 ... Control part, 9 ... Power supply unit, 10 ... Control circuit, 11 ... 1st feeder, 12 ... 2nd feeder, 13 ... Signal line, 14 ... Supercooling release device.

Claims (7)

A heat storage tank,
A heat storage material accommodated in the heat storage tank and capable of being supercooled;
An anode electrode immersed in the heat storage material;
A cathode electrode immersed in the heat storage material at a position separated from the anode electrode;
A power supply unit for applying a voltage between the anode electrode and the cathode electrode;
A plurality of grooves provided on the surface of the anode electrode;
With
The heat storage device in which the surface roughness Ra of the groove portion of the anode electrode is 0.05 μm or more and 4.0 μm or less.   2. The heat storage device according to claim 1, wherein a surface roughness Ra of the groove portion of the anode electrode is 0.05 μm or more and 3.0 μm or less.   2. The heat storage device according to claim 1, wherein a surface roughness Ra of the groove portion of the anode electrode is 0.05 μm or more and 1.6 μm or less.   The heat storage device according to claim 1, wherein the anode electrode is formed of a metal material mainly composed of silver.   The heat storage device according to claim 1, wherein the cathode electrode is formed of a metal material mainly composed of silver.   The heat storage device according to claim 1, wherein a voltage applied between the anode electrode and the cathode electrode is 1.0 V or more and 2.0 V or less. An anode electrode;
A cathode electrode provided at a position separated from the anode electrode;
A power supply unit for applying a voltage between the anode electrode and the cathode electrode;
A plurality of grooves provided on the surface of the anode electrode;
With
The supercooling release device, wherein the surface roughness Ra of the groove of the anode electrode is 0.05 μm or more and 4.0 μm or less.