WO2016031275A1 - Heat storage device - Google Patents

Abstract

A heat storage device 1 according to one embodiment of the present invention is provided with: a heat storage tank 3; a heat storage material 4 that is contained in the heat storage tank 3 and is able to be supercooled; an anode electrode 5 that is immersed in the heat storage material 4; a cathode electrode 6 that is immersed in the heat storage material 4 at a position apart from the anode electrode 5; a voltage application means 12 that applies a voltage between the anode electrode 5 and the cathode electrode 6; and a narrow space that is formed in the anode electrode 5 and is provided with a plurality of particle-like projections 8 on surfaces 7A facing each other.

Description

Heat storage device

Embodiment of this invention is related with the thermal storage apparatus which can accumulate | store heat | fever and can discharge | release it outside.

A heat storage device that uses supercooling of a heat storage material capable of phase change is known. 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.

It is called “nucleation” to release the supercooled state of the heat storage material in the liquid phase after being supercooled and to change the phase of the heat storage material from liquid to solid. If 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

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, voltage applying means for applying a voltage between the anode electrode and the cathode electrode, a narrow space formed in the anode electrode and having a plurality of particle-like convex portions formed on the surfaces of the opposing surfaces, Is provided.

The schematic diagram which showed the thermal storage apparatus of 1st Embodiment. The schematic diagram which expanded and showed the narrow space (groove part) of the anode electrode of the thermal storage apparatus shown in FIG. The schematic diagram which showed the other example of the shape of the narrow space (groove part) of the anode electrode of the thermal storage apparatus shown in FIG. The electron micrograph which expanded and showed the several particle-shaped convex part in the narrow space (groove part) shown in FIG. FIG. 5 is an electron micrograph of a cross section of the narrow space (groove) shown in FIG. 4 along the F5-F5 line direction (a direction crossing the narrow space (groove)). The schematic diagram which showed the crystal nucleus formed with the positive curvature (contact angle (theta)) concerning a reference example. The schematic diagram which shows the concept of the holding | maintenance state of the crystal nucleus of this embodiment, and shows the state in which the crystal nucleus was formed with the negative curvature (contact angle (theta)) with respect to the foundation | substrate (anode electrode 5). The schematic diagram which shows the concept of the holding | maintenance state of the crystal nucleus of this embodiment more concretely, and shows the state in which the crystal nucleus was formed with the negative curvature (contact angle (theta)) with respect to the foundation | substrate (anode electrode 5). The schematic diagram which showed the process in which an anode electrode becomes thin by multiple cycles of heat discharge | release, when providing the several particle-form convex part (crystal nucleus) on the surface of the anode electrode concerning the comparative example 1. FIG. FIG. 3 is a schematic diagram showing a process in which the anode electrode is thinned by multi-cycle heat release in the first embodiment. The heat storage apparatus of 1st Embodiment WHEREIN: When changing the width dimension (groove width) of the groove part of an anode electrode, the table | surface which shows the 1st experimental result which compared the nucleation probability after 30 second. The graph corresponding to the table | surface shown in FIG. The table | surface which shows the experimental result of the 2nd experiment which investigated the probability that a supercooled state will be maintained after 10-hour progress in the thermal storage apparatus of 1st Embodiment. 14 is a graph corresponding to the table shown in FIG. In the heat storage device according to the first embodiment, when the groove width of the groove and the average particle diameter (convex diameter) of the convex portion are changed as in Examples 1 to 7, the experimental results of examining the nucleation waiting time are shown. Table shown. The schematic diagram which showed the thermal storage apparatus of 2nd Embodiment. The schematic diagram which expanded and showed typically the circumference of an anode electrode in the modification of a 2nd embodiment.

[First embodiment]
Hereinafter, a heat storage device according to an embodiment of the present invention will be described in detail with reference to FIGS. As shown in FIG. 1, the heat storage device 1 includes a heat storage unit 2 and a control unit 11.

The control unit 11 includes a voltage application unit 12 and a control unit 13. The control unit 11 forms a unit, for example, and is provided on the outside (outer surface) of the heat storage tank 3, for example. The control unit 11 may be provided separately from the heat storage tank 3. Further, the control unit 11 may be connected to or incorporated in, for example, an air conditioner control system including the heat storage device 1. Further, the control unit 11 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 voltage applying means 12 is connected to the anode electrode 5 described later via the first power supply line 14. The negative electrode of the voltage application unit 12 is connected to the cathode electrode 6 described later via the second power supply line 15. That is, the voltage applying unit 12 can apply a voltage between the anode electrode 5 and the cathode electrode 6.

The voltage applying means 12 is configured as a power supply unit including a plurality of batteries and a switch circuit, for example. 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 voltage application means 12 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 by a switch circuit. The voltage applying means 12 may be a constant voltage power source or the like that can set the voltage applied between the anode electrode 5 and the cathode electrode 6 to an arbitrary value.

The control means 13 includes a memory, a calculation unit, an applied voltage controller, and the like. Various data necessary for controlling the heat storage device 1 is stored in the memory of the control means 13. The application voltage controller of the control means 13 and the voltage application means 12 are electrically connected via a signal line 16.

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 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. The 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. As shown in FIG. 1, the cathode electrode 6 is provided separately from the anode electrode 5. For example, the cathode electrode 6 is disposed so as to be entirely immersed in the heat storage material 4, but even if a part of the cathode electrode 6 is immersed in the heat storage material 4. Good.

As shown in FIG. 1, the anode electrode 5 is disposed, for example, in a state where the whole is immersed in the heat storage material 4, but a part of the anode electrode 5 may be immersed in the heat storage material 4. Therefore, the groove portion 7 formed in the anode electrode 5 is also 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. The anode electrode 5 is provided with one or a plurality of narrow spaces serving as a nucleation starting point of the heat storage material 4 in a part thereof. In the present embodiment, each of the narrow spaces is constituted by, for example, a groove portion 7 formed on the surface of the anode electrode 5. The groove portion 7 extends, for example, in a direction crossing the longitudinal direction L of the round bar-shaped anode electrode 5. For example, as shown in FIG. 2, the groove portion 7 has a surface 7 </ b> A that is adjacently opposed to each other as shown in FIG. 2, and a particle-like convex portion 8 (unevenness) is formed on the surface of the facing surface 7 </ b> A. In the present embodiment, the groove portion 7 has a shape (slit shape) in which the dimension between the opposing surfaces 7A (the groove width W) is substantially the same from the vicinity of the opening to the back of the groove portion 7. Is formed. In the present embodiment, the dimension between the opposing surfaces 7A is set to 0.5 to 300 μm. The shape of the groove portion 7 is not limited to the above-described slit shape. For example, as shown in FIG. 3, the width dimension W of the groove portion 7 gradually decreases from the vicinity of the opening portion to the deep portion of the groove portion V. It may be a letter shape.

FIG. 4 shows an electron micrograph of the groove 7 as viewed from above, and FIG. 5 shows an electron micrograph of a cross section of the groove 7. In the groove portion 7, a plurality of particulate convex portions 8 (unevenness) are formed. As apparent from FIGS. 4 and 5, the plurality of particulate projections 8 are formed over a plurality of layers and form a porous layer as a whole. As shown in these figures, a plurality of particulate projections 8 having a diameter of 0.1 to 1 μm are formed in the groove 7. For this reason, in this embodiment, the average particle diameter of the convex part 8 is 1 micrometer or less.

Subsequently, a method of creating a plurality of particulate projections 8 in the groove 7 of the anode electrode 5 will be described. First, the groove portion 7 is formed by cutting a silver round bar having a diameter of about 2 mm using a cutter with a blade angle of 30 ° to 40 °. Next, the groove width is adjusted to 0.5 to 300 μm by pressing the opening of the groove 7 and crushing the periphery of the opening.

Next, the silver bar provided with the groove 7 serving as the anode electrode 5 is connected to the positive electrode of the power source, and a separately prepared silver round bar is connected to the negative electrode of the power source. These positive electrode side silver bar and negative electrode side silver bar are immersed in an electrolytic solution, and a pulse wave of 0 V to 2 V is applied 1000 times between the positive electrode and the negative electrode in the electrolytic solution. The electrolyte solution is not particularly limited as long as it is a conductive liquid, and for example, saline solution, dilute hydrochloric acid, or the heat storage material 4 heated to a melting point or higher and melted may be used. The anode electrode 5 produced in this way is as shown in the photographs shown in FIGS. On the surface of the groove portion 7, particle-like convex portions 8 (unevenness) having a diameter of about 0.5 μm are formed.

Subsequently, with reference to FIG. 6 to FIG. 10, the operation of the heat storage device 1 of the present embodiment and the principle of nucleation will be described.

When heat is input to the heat storage tank 3, 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. As a result, the heat storage material 4 is dissolved and becomes a liquid phase. When the heat input is completed, the heat storage material 4 is lowered to a temperature below its melting point. Since the heat storage material 4 is a substance that can be supercooled as described above, the heat storage material 4 maintains the liquid phase state without solidifying even when the temperature drops from the liquid phase state to the melting point or lower. The heat storage material 4 is in a supercooled state and continues to store latent heat.

When the heat storage material 4 is held in a supercooled state, the control means 13 controls 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 to take out the latent heat of the heat storage material 4 is given to the control means 13 from the outside, the control means 13 performs control to apply the voltage set by the voltage application means 12 between both electrodes. In this case, as the voltage applied between both electrodes, the set voltage may be applied continuously for a certain period of time, or the set voltage may be applied in a plurality of times in the form of pulses.

When a voltage is applied between both electrodes by the voltage applying means 12, metal ions are eluted from the anode electrode 5 in contact with the heat storage material 4. Thereby, the supercooling of the heat storage material 4 in a liquid phase state is released. In this case, as the voltage applied between both electrodes, it is preferable to use a minimum voltage that can cancel the supercooling of the heat storage material 4 in the liquid phase state (nucleate the heat storage material 4). The inventors may apply a voltage of 1.0 V or more and 2.0 V or less, and more preferably a voltage of 1.5 V or more and 1.9 V or less when silver is used for the anode electrode 5. I found.

When a predetermined voltage is applied between the anode electrode 5 in contact with the heat storage material 4 made of sodium acetate trihydrate and the cathode electrode 6, the anode electrode 5 is formed on the surface of the groove 7 (nucleation start point). A metal oxidation reaction occurs, a water reduction reaction occurs on the cathode electrode 6 side, and a current flows through the heat storage material 4.

Nucleation of the heat storage material 4 is started from the groove 7 (nucleation start point) of the anode electrode 5. 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.

Here, if the crystal nucleus of the heat storage material 4 is present at the nucleation starting point, the voltage nucleation can be surely and instantaneously generated. However, when storing heat in the heat storage tank 3 as described above, it is necessary to raise the temperature of the heat storage material 4 to the melting point or higher, and a positive curvature (contact angle) is formed on the base (anode electrode 5) as shown in FIG. The crystal nuclei formed in θ) melt. On the other hand, if crystal nuclei are formed with a negative curvature (contact angle θ) with respect to the base (anode electrode 5) as shown in FIG. 7, they can exist stably even at temperatures above the melting point.

Based on such a theory, the groove portion 7 (nucleation start point portion) of the anode electrode 5 of the present invention is provided with a particle-like convex portion 8 (unevenness) on the surface thereof. Thereby, as shown in FIG. 8, the crystal nucleus which exists between the several adjacent particle-like convex parts 8 has a negative curvature. For this reason, even when exposed to the melting point or higher, crystal nuclei can exist stably, and the function as a starting point of voltage nucleation in a supercooled state can be maintained. The size of the crystal nucleus is preferably smaller than the critical diameter for nucleus growth in order to maintain supercooling. For this reason, it is preferable that the average particle diameter L of the granular convex part 8 is 1 micrometer or less.

Here, with reference to FIG. 9, an example (Comparative Example 1) in which a plurality of particulate projections 8 (crystal nuclei) are provided on the surface of the round bar-like anode electrode 5 will be described. As described above, when a voltage is applied between both electrodes by the voltage applying means 12, metal ions are eluted from the surface of the anode electrode 5. Therefore, when crystal nuclei exist only on the electrode surface as shown in FIG. 9, the electrode is thinned as nucleation is repeated, and the crystal nuclei disappear.

On the other hand, as shown in FIG. 10, in the present embodiment, particulate convex portions 8 (unevenness) are formed on the surface 7 </ b> A of the groove portion 7 which is a narrow space, and crystal nuclei are formed on the convex portions 8. Exists. Therefore, even if the surface of the anode electrode 5 is thinned by voltage application, the plurality of particulate projections 8 (unevenness) in the groove 7 are maintained, and the crystal nuclei existing there are also maintained.

It is preferable that the space | interval of 7 A of opposing surfaces of the groove part 7 is 300 micrometers or less. This is because, when the gap is further widened, the elution of metal ions from the facing surface at the time of voltage application increases as in the case where a plurality of particle-like convex portions 8 are provided on the electrode surface of Comparative Example 1. This is because crystal nuclei disappear. Moreover, in order to ensure the durability of the anode electrode 5 by elution of metal ions, it is preferable to provide a plurality of groove portions 7 (nucleation start point portions).

11 and 12, in the heat storage device 1 of the present embodiment, when the width dimension (groove width) of the groove portion 7 of the anode electrode is changed, the experimental results comparing the nucleation probabilities after 30 seconds. (First Experiment Result) will be described. The experiment was performed for each condition (groove width: 0.5 μm, 1 μm, 5 μm, 10 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm) in which the width of the groove was changed in the range of 0.5 μm to 600 μm. . On the inner surface of each groove portion 7, particle-like convex portions 8 having an average particle diameter of 0.5 μm are formed.

In the experiment, first, a nucleation operation in which a constant voltage of 1.7 V, for example, is applied between the electrodes (the anode electrode 5 and the cathode electrode 6) to the supercooled heat storage material 4 is repeated 1000 times. Then, after applying the voltage at the 1000th time, it was examined whether or not nucleation occurred within 30 seconds. The experiment was performed on three samples for each of the above conditions.

FIG. 11 shows a table of experimental results (probability of nucleation within 30 seconds after the voltage is applied for the 1000th time). FIG. 12 shows a graph representing the experimental results. As is clear from FIGS. 11 and 12, it was found that if the groove width was 300 μm or less, good nucleation response was exhibited even after 1000 cycles. On the other hand, it was found that when the groove width is larger than 300 μm, the nucleation response after 1000 cycles is extremely deteriorated.

Referring to FIGS. 13 and 14, in the heat storage device 1 of the present embodiment, when the particle diameter of the convex portion 8 in the groove portion 7 of the anode electrode 5 is changed, the supercooled state is maintained even after 10 hours. An experimental result (second experimental result) comparing the probabilities of being present will be described. The experiment was performed under various conditions (projection diameters: 0.1 μm, 0.5 μm, 1.0 μm, and 1.2 μm) in the range of 0.1 μm to 2.0 μm. 5 μm, 2.0 μm). In this second experiment, the width dimension of the groove 7 is set to 100 μm.

In the second experiment, the heat storage material 4 was heated and melted in the heat storage device 1 and then returned to room temperature to examine whether or not the supercooled state was maintained without spontaneous nucleation after 10 hours. The experiment was performed on three samples for each condition described above.

FIG. 13 shows a table of experimental results of the second experiment (probability of maintaining the supercooled state after 10 hours). FIG. 14 shows a graph representing the experimental results. As is clear from FIGS. 13 and 14, it was found that the supercooled state can be maintained when the particle diameter of the convex portion 8 is 1.0 μm or less. On the other hand, when the particle diameter of the convex portion 8 is larger than 1.0 μm, it is understood that the probability that the supercooled state cannot be maintained is extremely deteriorated (the probability that spontaneous nucleation occurs while being held at room temperature is increased). . If spontaneous nucleation occurs, the heat stored in the heat storage device 1 is released, and cannot be used as the heat storage device 1.

Referring to FIG. 15, the experimental results of examining the nucleation waiting time when the groove width of the groove 7 and the average particle diameter (convex diameter) of the protrusion 8 are changed as in Examples 1 to 6 are shown. explain.

(Example 1)
A groove 7 having a groove width of about 300 μm was formed by cutting a cutter having a blade angle of 40 ° into a silver round bar having a diameter of 2 mm to a depth of about 400 μm. Next, the silver bar in which the groove 7 is formed is connected to the positive electrode of the power source, and a silver electrode separately prepared for the negative electrode is connected, and the positive electrode and the negative electrode are immersed in the electrolyte. By applying a pulse wave of 0V to 2V in the electrolytic solution between both electrodes, particulate projections 8 (unevenness) having an average particle diameter of about 1 μm were formed on the surface of the groove 7.

The heat storage device 1 shown in FIG. 1 was configured using the prepared electrode as the anode electrode 5 and a silver bar having a diameter of 2 mm as the cathode electrode 6. In the nucleation operation, a constant voltage of 1.7 V is applied in a step waveform between both electrodes (the anode electrode 5 and the cathode electrode 6), and the crystallization of the heat storage material 4 starts from the time when this application is started. The time until was measured as the nucleation latency. When the nucleation start time passed 60 seconds, it was judged that crystallization was impossible (nucleation was impossible).

In this investigation, the nucleation waiting time in the first cycle (initial) and the nucleation waiting time after 1000 cycles (1000 times after nucleation) were measured. Here, one cycle means that after the heat storage material 4 is crystallized to be in a solid phase state, heat is applied to the heat storage material 4 to melt the crystal into a liquid phase state. It refers to the process until cooling. The initial cycle is the first cycle in which the first measurement is performed, and the 1000 cycle indicates that the above process is repeated 1000 times.

The results of the experiment are shown in the table in FIG. In Example 1, nucleation occurred instantaneously simultaneously with the voltage application in the initial cycle. In addition, good performance was maintained with a nucleation waiting time of 10 seconds even after 1000 cycles.

(Example 2)
A groove having a groove width of about 200 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 400 μm. Next, particulate projections 8 (unevenness) having an average particle diameter of about 1 μm were formed on the surface of the groove portion 7 in the same manner as in Example 1.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 2, nucleation occurred instantaneously at the same time as the voltage application in the initial cycle. In addition, good performance was maintained with a nucleation waiting time of 5 seconds even after 1000 cycles.

(Example 3)
A groove having a groove width of about 100 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 200 μm. Next, particulate projections 8 (unevenness) having an average particle diameter of about 1 μm were formed on the surface of the groove portion 7 in the same manner as in Example 1.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 3, nucleation occurred instantaneously at the same time as the voltage application in the initial cycle. In addition, good performance was maintained with a nucleation waiting time of 2 seconds even after 1000 cycles.

Example 4
A groove having a groove width of about 100 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 200 μm. Furthermore, the groove width was reduced to 10 μm by pressing the groove portion 7 to crush the electrode. Next, particulate projections (unevenness) having an average particle diameter of about 0.5 μm were formed on the surface of the groove portion 7 in the same manner as in Example 1.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 4, nucleation occurred instantaneously at the same time as voltage application in the initial cycle. In addition, even after 1000 cycles, nucleation occurred instantaneously simultaneously with the application of voltage, and good performance was maintained.

(Example 5)
A groove having a groove width of about 100 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 200 μm. Further, the groove width was reduced to 5 μm by pressing the groove portion 7 to crush the electrode. Next, in the same manner as in Example 1, particulate projections 8 (unevenness) having an average particle diameter of about 0.5 μm were formed on the surface of the groove.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 5, nucleation occurred instantaneously simultaneously with the voltage application in the initial cycle. In addition, even after 1000 cycles, nucleation occurred instantaneously simultaneously with the application of voltage, and good performance was maintained.

(Example 6)
A groove having a groove width of about 100 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 200 μm. Furthermore, the groove width was reduced to 1 μm by pressing the groove portion 7 and crushing the electrode. Next, particulate projections (unevenness) having an average particle diameter of about 0.5 μm were formed on the surface of the groove by the same method as in Example 1.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 6, nucleation occurred instantaneously simultaneously with the voltage application in the initial cycle. In addition, even after 1000 cycles, nucleation occurred instantaneously simultaneously with the application of voltage, and good performance was maintained.

(Example 7)
A groove having a groove width of about 100 μm was formed by cutting a cutter having a blade angle of 30 ° into a silver round bar having a diameter of 2 mm to a depth of about 200 μm. Further, the groove width was narrowed to 0.5 μm by pressing the groove portion 7 to crush the electrode. Next, in the same manner as in Example 1, particulate projections (irregularities) having an average particle diameter of about 0.1 to 0.3 μm were formed on the surface of the groove.

The produced electrode was used as the anode electrode 5, the heat storage device 1 of FIG. 1 was configured, and the same nucleation cycle test as in Example 1 was performed.

The results of the experiment are shown in the table in FIG. In Example 7, nucleation occurred instantaneously simultaneously with the voltage application in the initial cycle. In addition, even after 1000 cycles, nucleation occurred instantaneously simultaneously with the application of voltage, and good performance was maintained.

As in Example 1-7 above, in the electrode in which the facing surface 7A is formed adjacent to the anode electrode 5 and the particle-like convex portions 8 (unevenness) are formed on the surface of the facing surface 7A, It was found that good nucleation response was maintained even after 1000 nucleation cycles.

According to the first embodiment, the heat storage device 1 includes a heat storage tank 3, a heat storage material 4 accommodated in the heat storage tank 3 and capable of being supercooled, an anode electrode 5 immersed in the heat storage material 4, and the anode electrode 5. The cathode electrode 6 immersed in the heat storage material 4 at the separated position, the voltage applying means 12 for applying a voltage between the anode electrode 5 and the cathode electrode 6, and the surface of the opposing surface 7A formed on the anode electrode 5 A narrow space in which a plurality of particulate convex portions 8 are formed.

Generally, when a metal is used for the nucleation electrode, metal ions eluted from the anode 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 indispensable for voltage nucleation, and even if a nucleation member is provided on the electrode surface, if the nucleation operation is repeated, the metal electrode is thinned and the nucleation member is detached, resulting in nucleation. Loss of function.

According to the above configuration, since the plurality of particle-shaped convex portions 8 are arranged in the narrow space, even if the surface of the anode electrode 5 is thinned by applying a plurality of cycles of voltage, the plurality of particles are in the narrow space. The convex portion 8 is maintained. For this reason, even after a plurality of times of voltage application, crystal nuclei that do not melt even when the melting point is exceeded can be formed between the convex portions 8, and nucleation responsiveness can be improved. Thereby, the progress of the deterioration of the anode electrode 5 can be moderated. As described above, it is possible to provide a highly reliable heat storage device 1 that has a short nucleation waiting time and that has high repeated durability against the nucleation operation.

The narrow space is formed by the groove portion 7 provided in the anode electrode 5. According to this configuration, a narrow space can be easily formed with respect to the anode electrode 5.

The distance between the opposing surfaces of the narrow space is 0.5 to 300 μm. According to this structure, the space | interval of 7 A of opposing surfaces can be made very small. Thus, a plurality of particulates are obtained by performing heat extraction in a plurality of cycles (a cycle in which the solid phase is heated to become a liquid phase and then cooled and the heat storage material 4 is subcooled and nucleates when necessary). It is possible to reduce the probability that the convex portion 8 is eluted, and it is possible to prevent the crystal nuclei from being lost after the multiple cycles of heat extraction.

The average particle diameter of the plurality of particulate projections 8 is 0.1 to 1 μm. According to this configuration, the size of crystal nuclei (crystal nuclei that do not melt even when the heat storage material 4 is equal to or higher than the melting point) formed in the gap between the convex portions 8 can be made smaller than the critical diameter of the nucleus growth. it can. This can reduce the risk of nucleation and release of heat when not intended.

The surface of the facing surface 7A in the narrow space is porous by the plurality of particulate projections 8. According to this configuration, a large number of gaps can be formed between the protrusions 8, and crystal nuclei that do not melt even at the melting point or higher can be formed in the gaps. Thereby, the responsiveness of nucleation can be improved.

The anode electrode 5 is 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 of the heat storage device 1, the supercooled heat storage material can be stably nucleated.

[Second Embodiment]
Then, 2nd Embodiment of a thermal storage apparatus is described with reference to FIG. The second embodiment of the heat storage device 1 is different from the first embodiment in the configuration of the anode electrode 5, but the other parts are the same as those in the first embodiment. For this reason, parts different from the first embodiment will be mainly described below, and illustrations or descriptions of parts common to the first embodiment will be omitted.

The anode electrode 5 is formed, for example, by bending a metal (eg, silver) plate member having a thickness of about 0.1 to 0.2 mm into a “U” shape as shown in FIG. 16, for example. Is done. The material of the anode electrode 5 is not limited to silver but can be formed of a copper plate, a copper amalgam plate, or the like.

The anode electrode 5 is provided with a narrow space 21 serving as a nucleation starting point of the heat storage material 4 inside the “U” shape. The narrow space 21 is formed such that the dimension L in the depth direction is sufficiently longer than the dimension in the width direction W. On the surface of the opposing surface 7A of the narrow space 21, a particulate convex portion 8 (unevenness) is formed. In the present embodiment, the narrow space 21 is formed in a shape (slit shape) in which the dimension between the facing surfaces 7A is substantially the same from the vicinity of the opening to the back of the narrow space 21. . In the present embodiment, the dimension between the opposing surfaces 7A is set in the range of 0.5 to 300 μm, as in the first embodiment. The dimension between the opposing surfaces 7A is in the range of 0.5 to 300 μm by folding a silver plate-like member into a “U” shape and then applying a predetermined pressure to the narrow space 21 to crush it. Can be adjusted appropriately. Further, the dimension between the opposing surfaces 7A can be confirmed by observing a section of the anode electrode 5 bent in a “U” shape with an electron microscope.

In the narrow space 21, a plurality of particle-like convex portions 8 are formed on the opposing surface 7 </ b> A and the bottom of the narrow space. The diameter of the plurality of particle-like convex portions 8 is 0.1 to 1 μm, as in the first embodiment. Moreover, the average particle diameter of the convex part 8 is 1 micrometer or less. When the dimension between the opposing surfaces 7A of the narrow space 21 is 1 μm, the diameter of the convex portion 8 is about 0.5 μm, and the dimension between the opposing surfaces 7A is 0.5 μm. In this case, the diameter of the convex portion 8 is 0.1 to 0.3 μm.

The method for forming the plurality of particulate protrusions 8 is the same as in the first embodiment. That is, the anode electrode 5 bent in a “U” shape is connected to the positive electrode of the power source, and a separately prepared silver round bar is connected to the negative electrode of the power source. The anode electrode 5 on the positive electrode side and the silver bar on the negative electrode side are immersed in an electrolytic solution, and a pulse wave of 0 V to 2 V is applied 1000 times between the positive electrode and the negative electrode in the electrolytic solution. The composition of the electrolytic solution is the same as in the first embodiment. In the anode electrode 5 thus manufactured, as in the first embodiment, the particle-shaped protrusions 8 (unevenness) having a diameter of about 0.1 to 1 μm are formed inside the “U” shape. On the surface of the opposing surface 7A of the narrow space 21, a plurality of particulate convex portions 8 are formed over a plurality of layers. The plurality of particle-like convex portions 8 form a porous layer as a whole.

According to the second embodiment, the anode electrode 5 is formed by bending a plate-like member into a U shape, and the narrow space 21 is formed inside the U shape. According to this configuration, since the plurality of particulate projections 8 are arranged in the narrow space 21, even if the surface of the anode electrode 5 is thinned by applying a plurality of cycles of voltage, a plurality of the convex portions 8 are formed in the narrow space 21. The particulate convex portion 8 is maintained. For this reason, it is possible to improve the nucleation response even after a plurality of voltage applications. Thereby, the progress of the deterioration of the anode electrode 5 can be moderated, and the reliability of the heat storage device 1 can be improved. Further, as in the first embodiment, the narrow space 21 can be formed with a simple structure.

The distance between the opposing surfaces 7A of the narrow space 21 is 0.5 to 300 μm. According to this structure, the space | interval of 7 A of opposing surfaces can be made small. As a result, it is possible to reduce the probability that a plurality of particulate projections 8 are eluted by executing multiple cycles of heat extraction, and to prevent the disappearance of crystal nuclei after performing multiple cycles of heat extraction. it can.

(Modification)
Then, with reference to FIG. 17, the modification of the heat storage apparatus of 2nd Embodiment is demonstrated. In this modification, the anode electrode 5 is different from the second embodiment in that the anode electrode 5 is formed by winding a silver thin film around a metal round bar (for example, a silver bar). Common to the second embodiment. For this reason, a different part from 2nd Embodiment is mainly demonstrated, and illustration and description are abbreviate | omitted about the part which is common in 2nd Embodiment.

The anode electrode 5 of this modification is made of, for example, a metal (for example, about 0.1 to 0.2 mm thick) around a metal (for example, silver) round rod (mandrel) 5A having a diameter of about 2 mm. , Silver) thin film 5B is wound a plurality of times. For this reason, the anode electrode 5 is provided with a plurality of thin film 5B layers around a round bar (mandrel) 5A. A narrow space 21 similar to that in the second embodiment is formed between adjacent thin films 5B. In this narrow space 21, a plurality of particulate projections 8 are formed. The dimension between adjacent (opposing) thin film 5B layers can be appropriately set within a range of 0.5 to 300 μm. That is, the dimension between the adjacent (opposing) thin film 5B layers is such that after the silver thin film 5B is wound around the silver round bar 5A, a predetermined pressure is applied from the upper side of the thin film 5B to form the narrow space 21. By crushing, it can be appropriately adjusted in the range of 0.5 to 300 μm. The material for the anode electrode 5 is not limited to silver. The anode electrode 5 can employ the same structure as described above using copper, copper amalgam, or the like.

In the narrow space 21, a plurality of particulate convex portions 8 are formed. The diameter of the plurality of particulate projections 8 is 0.1 to 1 μm, as in the first and second embodiments. Moreover, the average particle diameter of the convex part 8 is 1 micrometer or less. In addition, when the dimension between the layers of the adjacent thin film 5B which comprises the narrow space 21 is 1 micrometer, the diameter of the convex part 8 is about 0.5 micrometer, and between the layers of the adjacent thin film 5B Is 0.5 μm, the diameter of the protrusion 8 is about 0.1 to 0.3 μm.

The method for forming the plurality of particulate projections 8 is the same as in the first embodiment and the second embodiment. That is, an anode electrode 5 in which a silver thin film 5B is wound around a silver round bar 5A is connected to the positive electrode of the power source, and a separately prepared silver round bar is connected to the negative electrode of the power source. The anode electrode 5 on the positive electrode side and the silver bar on the negative electrode side are immersed in an electrolytic solution, and a pulse wave of 0V-2V is applied 1000 times between the positive electrode and the negative electrode in the electrolytic solution. The composition of the electrolytic solution is the same as in the first embodiment. In the anode electrode 5 produced in this way, as in the first and second embodiments, the particle-shaped convex portions 8 (unevenness) having a diameter of about 0.1 to 1 μm are formed inside the narrow space 21. The On the surface of the thin film 5 </ b> B constituting the narrow space 21, a plurality of particulate projections 8 are formed over a plurality of layers. The plurality of particle-like convex portions 8 form a porous layer as a whole.

The same effect as that of the anode electrode 5 of the second embodiment can be exhibited by the anode electrode 5 of the present modification. As a result, the highly reliable heat storage device 1 with good nucleation responsiveness can be provided even after multiple voltage applications.

Although several embodiments of the present invention have been described, these embodiments are presented as examples 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, 3 ... Thermal storage tank, 4 ... Thermal storage material, 5 ... Anode electrode, 6 ... Cathode electrode, 7 ... Groove part, 7A ... Opposite surface, 8 ... Convex part, 12 ... Voltage application means, 21 ... Narrow space .

Claims (16)

1. 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;
   Voltage applying means for applying a voltage between the anode electrode and the cathode electrode;
   Formed in the anode electrode, a narrow space in which a plurality of particulate projections are formed on the surface of the facing surface; and
   A heat storage device comprising:
2. The heat storage device according to claim 1, wherein the narrow space is formed by a groove provided in the anode electrode.
3. The heat storage device according to claim 2, wherein an interval between opposing surfaces of the narrow space is 0.5 to 300 µm.
4. The heat storage device according to claim 3, wherein an average particle diameter of the plurality of particulate convex portions is 0.1 to 1 µm.
5. The heat storage device according to claim 4, wherein a surface of the facing surface of the narrow space is made porous by the plurality of particulate convex portions.
6. The heat storage device according to claim 5, wherein the anode electrode is made of a metal mainly composed of silver.
7. The anode electrode is formed by bending a plate-like member into a U shape,
   The heat storage device according to claim 1, wherein the narrow space is formed inside the U-shape.
8. The heat storage device according to claim 7, wherein an interval between opposing surfaces of the narrow space is 0.5 to 300 µm.
9. The heat storage device according to claim 8, wherein an average diameter of the plurality of particulate convex portions is 0.1 to 1 µm.
10. The heat storage device according to claim 9, wherein a surface of the facing surface of the narrow space is made porous by the plurality of particulate convex portions.
11. The heat storage device according to claim 10, wherein the anode electrode is made of a metal mainly composed of silver.
12. The anode electrode is formed by winding a metal thin film around a mandrel,
    The heat storage device according to claim 1, wherein the narrow space is formed between the adjacent thin films.
13. The heat storage device according to claim 12, wherein an interval between the thin films facing each other in the narrow space is 0.5 to 300 µm.
14. The heat storage device according to claim 13, wherein an average diameter of the plurality of particulate convex portions is 0.1 to 1 µm.
15. The heat storage device according to claim 14, wherein a surface of the facing surface of the narrow space is made porous by the plurality of particulate convex portions.
16. The heat storage device according to claim 15, wherein the anode electrode is made of a metal mainly composed of silver.

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