JP2016011787A - Heat storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve improvement of a heat storage amount and simplification of a structure.SOLUTION: A heat storage tank 2 is configured by including an inner tank 4 and an outer tank 5 partitioned by a partition wall 3 with a heater 20 for partitioning. In the inner tank 4, a heat storage material 6 for phase change which goes through a phase change within a heat storage temperature range and in which density of a solid phase is larger than that of a liquid phase is charged. At an upper position of the inner tank 4, a heat transfer pipe 16 for heat take-out is arranged by being submerged in the heat storage material 6 for phase change. A solid heat storage material 7 is charged in the outer tank 5. A heat storage system 1 is formed by providing a hot plate 10 for heating the inner tank 4 for heat storage and each of the heat storage materials 6, 7 in the outer tank 5 at a lower end part of the heat storage tank 2. In the heat storage tank 2, a heat storage amount per unit volume of the heat storage tank 2 is improved by performing heat storage by utilizing latent heat when the heat storage material 6 for phase change in the inner tank 4 goes through solid-liquid phase change and the solid heat storage material 7 in the outer tank 5. It is not necessary that the heat transfer pipe 16 for heat take-out and the hot plate 10 are distributed to the entire heat storage tank 2.

Description

  The present invention relates to a heat storage system used for heat storage.

  In solar thermal power generation, sunlight is collected and collected in a heat collection area, steam is generated by the collected heat, and a steam turbine is driven by the steam to generate power.

  In this type of solar thermal power generation, a heat storage system is generally provided in order to compensate for power generation during nighttime or when the amount of solar radiation cannot be obtained and to suppress a transient change in output power.

  This type of heat storage system initially uses a molten salt that becomes a liquid phase in the entire heat storage temperature range, or a solid phase in the entire heat storage temperature range, such as magnesia. A method of storing heat by using sensible heat of these heat storage materials has been adopted.

  Moreover, as a heat storage system for improving the heat storage density, a heat storage tank is filled with a heat storage material that causes a phase change between a solid phase and a liquid phase in the heat storage temperature range, and heat storage is performed using the latent heat of the heat storage material. Conventionally, a heat storage system of the type that performs the above has been considered.

Examples of heat storage materials that cause a phase change between a solid phase and a liquid phase in this type of heat storage temperature range include CsNO ₃ and NaNO ₃ , LiNO ₃ and LiOH, LiNO ₃ and NaNO ₃ , KNO ₃ and NaNO ₃ , and NaNO _3. It has been proposed to use a heat storage material composed of a binary mixed salt of a combination of RbNO ₃ , RbNO ₃ , LiBr and LiOH, LiBr and NaNO ₃ (for example, see Patent Document 1).

  Furthermore, as another type of heat storage system, a heat storage tank is filled with a solid-liquid mixed heat storage material obtained by mixing a solid heat storage material such as magnesia with a heat storage material that causes a solid-liquid phase change in the heat storage temperature range. A heat storage system has been proposed in the past. According to such a heat storage system, since the solid heat storage material has a specific heat larger than that of the phase change heat storage material, the amount of heat stored per unit volume in the heat storage tank can be improved (for example, patents). Reference 2).

  However, in the conventional heat storage system using both the phase change heat storage material and the solid heat storage material, since the fluidity of the solid-liquid mixed heat storage material filled in the heat storage tank is poor, the solid heat storage tank is filled with the solid heat storage material. A heater for heating the liquid mixed heat storage material for heat storage and a heat transfer tube for taking out heat from the solid-liquid mixed heat storage material need to be arranged over the entire area of the heat storage tank. Therefore, the structure of the heater and the heat transfer tube is increased, and the structure in the heat storage tank is complicated. Further, as the structure in the conventional heat storage tank becomes complicated, the manufacturing cost increases.

JP 2013-224343 A Japanese Patent Laid-Open No. 5-256591

  Therefore, the present invention aims to improve the amount of heat stored per unit volume of the heat storage tank by performing heat storage using both a heat storage material that causes a solid-liquid phase change in the heat storage temperature range and a solid heat storage material. It is possible to reduce the configuration of the heating means and the heat transfer tubes without having to distribute the heating means for heating for heat storage provided in the heat storage tank and the heat transfer tubes for taking out heat throughout the heat storage tank. Thus, an object of the present invention is to provide a heat storage system that can simplify the structure.

  In order to solve the above-mentioned problem, the present invention comprises a partition wall extending in the circumferential direction at a position near the outer periphery in the tank, corresponding to claim 1, wherein the inner region is the inner region, and the outer region. A heat storage tank having an outer tank and a phase change heat storage material that fills the inner tank and causes a solid-liquid phase change in a preset heat storage temperature range, and the solid phase density is greater than the liquid phase density. And a solid heat storage material filled in the outer tank, which becomes a solid phase in the heat storage temperature range, and at the lower end of the heat storage tank, provided at the bottom of the inner tank and the outer tank, for each of the heat storage materials A hot plate that performs heating for heat storage, and a heat transfer tube for taking out the heat possessed by the phase change heat storage material, provided at an upper position of the inner tub and immersed in the phase change heat storage material, And a partition wall heater for heating the partition wall to a solid-liquid phase change temperature of the phase change heat storage material. And thermal storage system.

  Further, corresponding to claim 2, in the configuration corresponding to claim 1, the outer tank of the heat storage tank is filled with a solid heat storage material in the form of small pieces, and the partition wall of the heat storage tank is filled with the solid heat storage material. The phase change heat storage material is provided with a communication hole that allows passage of the liquid phase of the phase change heat storage material so that the inner tank and the outer tank communicate with each other. It is set as the structure filled with the clearance gap between the small pieces of the said solid heat storage material by moving to an outer tank through this communicating hole.

  Furthermore, corresponding to claim 3, in the configuration corresponding to claim 1, the outer tank of the heat storage tank is filled with a solid heat storage material in the form of small pieces, and the pieces of the solid heat storage material in the outer tank are filled with each other. The gap is filled with a molten salt heat storage material.

According to the heat storage system of the present invention, the following excellent effects are exhibited.
(1) By storing heat using both the latent heat of the solid-liquid phase change in the heat storage temperature range of the phase change heat storage material and the sensible heat of the solid heat storage material, the amount of heat storage per unit volume of the heat storage tank Improvement can be achieved.
(2) In the heat storage tank, it is possible to eliminate the need to distribute the heating means for heating for heat storage and the heat transfer tube for taking out heat throughout the heat storage tank. Therefore, the structure of the heating means and the heat transfer tube can be reduced, and the structure can be simplified.

It is a general | schematic cutting side view which shows one Embodiment of the thermal storage system of this invention. It is a general | schematic cutting side view which shows the other form of implementation of this invention. It is a general | schematic cutaway side view which shows other form of implementation of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows one embodiment of the heat storage system of the present invention.

  The heat storage tank 2 used in the heat storage system 1 of the present invention includes a partition wall 3 extending in the circumferential direction at a position near the outer periphery in the tank, and an inner region partitioned by the partition wall 3 is an inner tank 4, and an outer region. Is configured as an outer tub 5.

In the inner tank 4, a phase change occurs between a solid phase and a liquid phase in a preset heat storage temperature range (T _min <T <T _max ), and the density of the solid phase is higher than the density of the liquid phase. A large phase change heat storage material 6 is filled. In FIG. 1, the solid phase of the phase change heat storage material 6 is hatched. The details of the phase change heat storage material 6 will be described later.

The outer tub 5 is filled with a solid heat storage material 7 that is always in a solid phase in the heat storage temperature range (T _min <T <T _max ) in a small piece. For example, magnesia may be used as the solid heat storage material 7. Thereby, in the said outer tank 5, while performing the thermal storage using the sensible heat of the said solid heat storage material 7, the heat retention of the said inner tank 4 using the magnitude | size of the specific heat of this solid heat storage material 7 is performed. The heat storage and heat retaining layer 8 is formed.

  The partition wall 3 is provided with a plurality of communication holes 9 penetrating in the inner and outer directions to communicate the inner tub 4 and the outer tub 5 in the vertical and circumferential directions. The size of the communication hole 9 is set to be smaller than the size of the small piece of the solid heat storage material 7 and allows the liquid phase of the phase change heat storage material 6 to pass while blocking the passage of the solid heat storage material 7. I have to do it.

  Thereby, in the heat storage tank 2, a part of the liquid phase of the phase change heat storage material 6 filled in the inner tank 4 passes through the communication hole 9 of the partition wall 3 and moves to the outer tank 5. For this reason, in the outer tub 5, the liquid phase of the phase change heat storage material 6 is filled in the gaps between the filled pieces of the solid heat storage material 7. In the solid heat storage material 7 in this state, since the liquid phase of the phase change heat storage material 6 exists in the gap between the small pieces, the thermal resistance between the small pieces is reduced.

  Furthermore, in the heat storage tank 2, since a part of the phase change heat storage material 6 is in direct contact with the solid heat storage material 7 in the outer tank 5, the phase change heat storage material 6 and the solid heat storage material 7 The mutual heat transfer efficiency is high.

  At the lower end of the heat storage tank 2, a hot plate 10 is provided in series below the inner tank 4 and the outer tank 5 as plate-like heating means for performing heat storage.

  The hot plate 10 includes a plate member 11 for forming the inner bottom surface of the inner tub 4 and the inner bottom surface of the outer tub 5 as flat surfaces, and heating means provided below the plate member 11. It is configured.

  The plate member 11 is configured to disperse the solid phase of the phase change heat storage material 6 that is generated and settles in the inner tank 4 when the temperature of the heat storage tank 2 is lowered, on the upper side of the plate member 11. This is because it is preferable to deposit and to receive the load of the deposit distributed on the surface of the plate member 11.

  The heating means of the hot plate 10 has a configuration in which, for example, a heat medium flow path 12 through which the heating heat medium 13 is circulated is provided below the plate member 11. The heat medium flow path 12 is a flow path of the heating medium 13 in the plane of the plate member 11 so that the entire surface of the plate member 11 can be heated as uniformly as possible by the heat of the heating medium 13. Of course, the arrangement, shape, cross-sectional area of the flow path, etc. may be set as appropriate. In FIG. 1, for convenience of illustration, the flow path of the heating heat medium 13 in the heat medium flow path 12 is simplified.

  A heating heat medium supply line 14 is connected to the upstream end of the heat medium flow path 12 for guiding the heating heat medium 13 from an external heating medium supply means (not shown). A heating heat medium return for returning the heating heat medium 13 after flowing through the heat medium flow path 12 to the heating heat medium supply means is provided at the downstream end of the heat medium flow path 12. Line 15 is connected. Further, the heating medium supply means includes a heat exchanging unit for supplying the heating medium 13 with heat from a heat source (not shown) such as a heat collecting unit of solar thermal power generation for heating. And

For the heating heat medium 13, a heat medium that is in a liquid phase is selected and used over the entire heat storage temperature range (T _min <T <T _max ), or even a slightly higher temperature range, or Steam should be used.

  Thereby, the heated heating medium 13 can be circulated and supplied to the heating medium flow path 12 of the hot plate 10 from the heating medium supplying means. Therefore, in the hot plate 10, the phase change in the inner tub 4 is performed via the plate member 11 by the heat of the heating medium 13 that is sequentially supplied to the heating medium flow path 12 in a heated state. The heat storage material 6 and the solid heat storage material 7 and the phase change heat storage material 6 in the outer tub 5 can be heated from below.

  At the upper position in the inner tank 4, a heat transfer tube 16 for heat extraction is provided so as to be immersed in the phase change heat storage material 6. It is assumed that the heat transfer tube 16 is supported from the wall surface of the inner tank 4 or the ceiling portion of the heat storage tank 2 through a support member (not shown).

  The surface (outer surface) in contact with the phase change heat storage material 6 in the heat transfer tube 16 is preferably made of glass. According to the heat transfer tube 16 having such a configuration, the solid phase of the heat storage material for phase change 6 generated by solidifying around the heat transfer tube 16 is prevented from adhering to the surface of the heat transfer tube 16 as will be described later. it can.

  A heat extraction heat medium supply line 18 for guiding the heat extraction heat medium 17 from an external heat extraction heat medium supply means (not shown) is connected to the upstream end of the heat transfer tube 16. A heat extraction heat medium return line for returning the heat extraction heat medium 17 after flowing through the heat transfer pipe 16 to the heat extraction heat medium supply means is provided at the downstream end of the heat transfer pipe 16. 19 is connected. Furthermore, the heat extraction heat medium supply means includes a heat exchanging section for applying the heat of the heat extraction heat medium 17 to a desired heat load (not shown).

  Thus, the heat extraction heat medium 17 can be circulated and supplied to the heat transfer tube 16 from the heat extraction heat medium supply means. Therefore, the heat extraction heat medium 17 that flows through the heat transfer tube 16 is sequentially heated by heat exchange with the phase change heat storage material 6 existing around the heat transfer tube 16, Heat held by the heat extraction heat medium 17 recovered by the heat extraction heat medium supply means in a heated state is applied to the heat load.

  As described above, when the heat extraction heat medium 17 flowing in the heat transfer tube 16 is heated by heat exchange with the phase change heat storage material 6 existing around the heat transfer tube 16, the heat transfer tube The temperature of the phase change heat storage material 6 existing around 16 is relatively lowered. When the temperature drop of the phase change heat storage material 6 occurs at the phase change temperature between the liquid phase and the solid phase, the phase change heat storage material 6 is liquid around the heat transfer tube 16 as shown in FIG. Solidifies from the phase to form a solid phase. The solid phase of the phase change heat storage material 6 has a higher density than the liquid phase, and therefore settles in the liquid phase.

  In the inner tank 4, the heat transfer tube 16 is provided only at the upper position thereof, so that even if a solid phase of the phase change heat storage material 6 having a lowered temperature is generated around the heat transfer tube 16, The solid phase settles and is deposited on the upper side of the hot plate 10 provided at the bottom of the inner tank 4.

  Therefore, in the inner tank 4, the solid phase of the phase change heat storage material 6 does not stay around the heat transfer tube 16, and the heat transfer tube 16 has a temperature higher than the phase change temperature. The liquid phase of the phase change heat storage material 6 is continuously supplied. For this reason, it can suppress that the efficiency of the heat transfer between the said heat | fever storage material 6 for phase changes and the heat-extraction heat medium 17 which distribute | circulates the inside of the said heat exchanger tube 16 falls.

  The partition wall 3 is provided with a partition wall heater 20 for raising the temperature of the partition wall 3.

  The partition heater 20 is attached to the outer peripheral surface or inner peripheral surface of the partition 3 where it does not interfere with the communication hole 9 so as to extend over the entire length of the partition 3 in the vertical direction. FIG. 1 shows a configuration in which the partition wall heater 20 is provided on the outer peripheral surface of the partition wall 3.

  The partition wall heater 20 may be an electric heater, for example. Alternatively, similarly to the hot plate 10, the partition wall heater 20 may be a heater having a heat medium flow path for circulating steam or other liquid phase heat medium.

  Further, the partition wall heater 20 performs the heating of the partition wall 3 by the partition wall heater 20 in synchronism with the heating of the inner tank 4 and the outer tank 5 by the hot plate 10, that is, when the heat storage tank 2 stores heat. To be controlled.

  The heating temperature of the partition wall 3 by the partition wall heater 20 is set to a temperature at which the phase change heat storage material 6 becomes a liquid phase.

  Thereby, when the inner tank 4 is heated by the hot plate 10, the solid phase of the heat storage material for phase change 6 deposited on the upper side of the hot plate 10 in the inner tank 4 is heated from below. First, the liquid phase is melted from the portion in contact with the upper surface of the hot plate 10.

  At this time, by operating the partition heater 20 at the same time, the solid phase of the phase change heat storage material 6 existing in the vicinity of the inner peripheral surface of the partition wall 3 is melted in the inner tub 4 to form a liquid phase. Can be made. For this reason, the solid phase deposit of the phase change heat storage material 6 on the hot plate 10 is prevented from sticking to the inner peripheral surface of the partition wall 3. Further, the liquid phase of the phase change heat storage material 6 generated at the portion in contact with the upper surface of the hot plate 10 is caused to flow at a position along the inner peripheral surface of the partition wall 3, so that the phase change heat storage material 6 It can be moved above the solid deposit.

  As a result, in the inner tank 4, the solid phase deposit of the phase change heat storage material 6 can be pressed against the upper surface of the hot plate 10 by its own weight. The liquid phase layer of the phase change heat storage material 6 formed between the objects can be thinned. As a result, the efficiency of heat transfer from the hot plate 10 to the solid phase of the phase change heat storage material 6 can be increased.

  Further, when the outer tub 5 is heated by the hot plate 10, the temperature of the solid heat storage material 7 and the phase change heat storage material 6 in the outer tub 5 rises from those present near the lower end close to the hot plate 10. Thus, when the solid phase of the heat storage material 6 for phase change exists in the outer tub 5, the melting occurs from the lower side.

  At this time, by operating the partition heater 20 simultaneously, the solid phase of the phase change heat storage material 6 existing in the vicinity of the outer peripheral surface of the partition wall 3 in the outer tank 5 as in the inner tank 4. Can be melted into a liquid phase. For this reason, the liquid phase produced by melting of the solid phase of the phase change heat storage material 6 on the lower side in the outer tub 5 is allowed to flow at a position along the outer peripheral surface of the partition wall 3 and be moved upward. Further, it can be moved into the inner tank 4 through the communication hole 9 of the partition wall 3.

  For this reason, in the phase change heat storage material 6 existing in the gap between the small pieces of the solid heat storage material 7 filled in the outer tub 5, volume expansion occurs with the phase change from the solid phase to the liquid phase. Even so, the volume change can be easily absorbed by the flow (movement) of the liquid phase of the phase change heat storage material 6. Therefore, when the solid heat storage material 7 and the phase change heat storage material 6 in the outer tank 5 are heated, the possibility that an excessively large pressure acts locally on the heat storage tank 2 and the partition wall 3 can be prevented. is there.

Furthermore, due to unforeseen circumstances, the entire heat storage tank 2 is filled in the inner tank 4 and the outer tank 5 by lowering the temperature below the heat storage temperature range (T _min <T <T _max ). When all of the phase change heat storage materials 6 are in a solid phase, the phase change heat storage material 6 is melted in the vertical direction by operating the partition heater 20, The temperature inside the heat storage tank 2 is raised so that it can be returned to the heat storage temperature range.

  Here, the phase change heat storage material 6 will be described.

  Phase change heat storage that solidifies around the heat transfer tube 16 when the heat of the phase change heat storage material 6 in the inner tank 4 is taken out using the heat extraction heat medium 17 that circulates the heat transfer tube 16. When the solid phase of the material 6 adheres to the surface of the heat transfer tube 16, the solid phase of the phase change heat storage material 6 does not settle, leading to a decrease in heat transfer efficiency.

As a result of research conducted by the present inventors, in order to make it difficult for the solid phase of the phase change heat storage material 6 to adhere to the surface of the heat transfer tube 16, the heat storage material for phase change 6 is the heat storage material. It has been found that it is advantageous to use a non-eutectic composition binary mixed salt that is in a solid-liquid coexistence state at the minimum heat storage temperature T _min in the temperature range (T _min <T <T _max ). .

For example, when assuming application to a high-temperature system such as solar thermal power generation, the minimum heat storage temperature T _{min in} the heat storage temperature range (T _min <T <T _max ) desired for the heat storage system is 150 ° C. or higher, preferably 200 ℃ or more.

Therefore, as an example, the heat storage temperature range (T _min <T <T _max ) in the heat storage system 1 of the present invention is set such that the maximum heat storage temperature T _max is 400 ° C. and the minimum heat storage temperature T _min is 250 ° C. .

As the phase change heat storage material 6 suitable for this condition, for example, potassium nitrate (KNO ₃ ) and sodium nitrate (NaNO ₃ ) among the combinations of binary mixed salts shown in Patent Document 1 are used. There is a binary mixed salt mixed with a composition that is non-eutectic.

The mixture of potassium nitrate and sodium nitrate becomes a eutectic with a composition in which the molar fraction of sodium nitrate is 0.49. Therefore, a composition other than this eutectic is used, and the minimum heat storage temperature _Tmin . A solid-liquid coexistence state is established at 250 ° C. As a specific composition example, a composition having a sodium nitrate molar fraction of 0.786 (mass fraction of 0.755) can be used as the phase change heat storage material 6.

Further, as the phase change heat storage material 6, of the combination of the mixed salts of two-component systems the disclosed in Patent Document 1, a mixture of CsNO ₃ and NaNO _3, mixture of LiNO ₃ and NaNO _3, NaNO ₃ It is also possible to use a mixture of RbNO ₃ .

When the mixture of CsNO ₃ and NaNO ₃ is used, the molar fraction of NaNO ₃ is 0.902 (mass fraction is 0.801), and when the mixture of LiNO ₃ and NaNO ₃ is used, NaNO ₃ When the molar fraction is 0.877 (mass fraction is 0.898) and a mixture of NaNO ₃ and RbNO ₃ is used, the molar fraction of RbNO ₃ is 0.105 (mass fraction is 0.169). By doing so, a solid-liquid coexistence state can be obtained at 250 ° C., which is the minimum heat storage temperature T _min .

Furthermore, when the minimum heat storage temperature T _{min in} the heat storage temperature range (T _min <T <T _max ) is set to 280 ° C., the phase change heat storage material 6 is shown in Patent Document 1. Among combinations of binary mixed salts, it is possible to use a mixture of LiBr and NaNO ₃ . In this case, by setting the molar fraction of NaNO ₃ to 0.964 (mass fraction of 0.963), a solid-liquid coexistence state can be _achieved at 280 ° C., which is the lowest heat storage temperature T _min .

  When a binary mixed salt having a non-eutectic composition as described above is used as the phase change heat storage material 6, the solid phase of the phase change heat storage material 6 generated by solidifying around the heat transfer tube 16 is the cooling surface. It does not adhere strongly to the surface of the heat transfer tube 16 and is easily peeled off.

  This is because the solid fraction near the cooling surface increases locally when it begins to solidify, so that the molten salt forming a liquid phase with a relatively low melting point enters between the cooling surface and the solid phase. This is thought to be due to the progress of solidification, and is attributed to the existence of a solid-liquid coexistence region of non-eutectic molten salt with a temperature range.

  Therefore, in the heat storage system 1 of the present invention, the phase change heat storage material 6 is gradually increased from the liquid phase state in the inner tank 4, that is, the temperature is gradually decreased. It is possible to suppress the phase change heat storage material 6 that has become a solid phase from being in close contact with the surface of the heat transfer tube 16 by performing the control.

  When heat storage is performed using the heat storage system 1 of the present invention having the above-described configuration, the heating heat medium 13 supplied in a heated state through the heating heat medium supply line 14 from the heating heat medium supply means, Continuously supplied to the heat medium flow path 12 of the hot plate 10. Thereby, since the hot plate 10 is heated, the heated hot plate 10 causes the phase change heat storage material 6 in the inner tank 4, the solid heat storage material 7 and the phase change heat storage in the outer tank 5. The material 6 is heated from below.

  At this time, as described above, in the heat storage system 1 of the present invention, the efficiency of heat transfer from the hot plate 10 to the solid phase of the phase change heat storage material 6 is high. Heating can be performed efficiently. The heat applied to the phase change heat storage material 6 is used as latent heat when the phase change heat storage material 6 undergoes a phase change from a solid phase to a liquid phase, and the temperature of the phase change heat storage material 6 increases. It can be absorbed as sensible heat.

  Furthermore, since the solid heat storage material 7 in the outer tub 5 can be directly heated by the hot plate 10 provided below the outer tub 5, the solid heat storage material 7 can also be efficiently heated. . The heat applied to the solid heat storage material 7 can be absorbed as sensible heat when the temperature of the solid heat storage material 7 rises.

  Therefore, the heat storage system 1 of the present invention can increase the heat storage density and the amount of heat stored per unit volume in the heat storage tank 2 as compared with the conventional heat storage system using only the phase change heat storage material 6. Can be high.

  In the heat storage system 1 of the present invention, the heat applied from the hot plate 10 to the phase change heat storage material 6 in the inner tub 4, the solid heat storage material 7 and the phase change heat storage material 6 in the outer tub 5 is provided. When a predetermined target heat storage amount is reached, supply of the heating heat medium 13 to the hot plate 10 is stopped from the heating medium supply means.

  In this state, in the heat storage system 1 of the present invention, the heat of the phase change heat storage material 6 in the inner tub 4, the solid heat storage material 7 and the phase change heat storage material 6 in the outer tub 5 is retained.

  At this time, in the heat storage system 1 of the present invention, the outer tank 5 surrounding the entire circumferential direction is provided outside the inner tank 4 filled with the phase change heat storage material 6, and the solid heat storage material 7 having a large specific heat. Therefore, the outer tub 5 filled with the solid heat storage material 7 has the function of performing the heat storage described above, and the heat from the phase change heat storage material 6 in the inner tub 4 to the outside. The function as the heat storage and heat retaining layer 8 for suppressing the release is achieved.

  Therefore, the heat storage system 1 of the present invention has a high heat retention performance of the phase change heat storage material 6.

  When taking out the stored heat from the heat storage system 1 of the present invention, the heat extraction heat medium 17 supplied through the heat extraction heat medium supply line 18 from the heat extraction heat medium supply means is used as the heat transfer tube. 16 is continuously supplied to flow through the heat transfer tube 16. As a result, the heat extraction heat medium 17 is heated by heat exchange with the phase change heat storage material 6 existing around the heat transfer tube 16 while flowing through the heat transfer tube 16, and thus is heated. Then, heat is recovered from the heat extraction heat medium 17 taken out in the state, and the recovered heat is applied to a desired heat load.

  At this time, as described above, the solid phase of the heat storage material for phase change 6 generated by solidifying around the heat transfer tube 16 is settled toward the bottom in the inner tank 4 to surround the heat transfer tube 16. Therefore, in the heat storage system 1 of the present invention, the efficiency of heat transfer from the phase change heat storage material 6 to the heat extraction heat medium 17 is increased, and the stored heat is efficiently scattered. Can do.

  Furthermore, in the present heat storage system 1 having the above-described configuration, the liquid phase of the phase change heat storage material 6 passing through the communication hole 9 provided in the partition wall 3 and the solid heat storage material 7 filled in the outer tub 5. Direct heat transfer to and from. For this reason, the heat of the solid heat storage material 7 in the outer tub 5 is efficiently transmitted to the phase change heat storage material 6 in the inner tub 4 and is efficiently used for heating the heat extracting heat medium 17. Is done.

  Thus, according to the heat storage system 1 of the present invention, heat storage is performed by using both the phase change heat storage material 6 that causes a solid-liquid phase change in the preset heat storage temperature range and the solid heat storage material 7. It is possible to improve the amount of heat stored per unit volume of the heat storage tank 2.

  Furthermore, the hot plate 10 serving as a heating means for heating the heat storage materials 6 and 7 in the heat storage tank 2 may be provided only at the lower end of the heat storage tank 2, while the phase change is performed. Since the heat transfer tubes 16 for extracting heat by heat exchange with the heat storage material 6 need only be provided at the upper position of the inner tank 4, the structure of the hot plate 10 and the heat transfer tubes 16 is reduced, and the structure Can be simplified. Therefore, the manufacturing cost can be reduced.

  Next, FIG. 2 shows another embodiment of the present invention.

  As shown in FIG. 2, the heat storage system 1A of the present embodiment has a configuration similar to that shown in FIG. 1, but instead of the configuration using the partition 3 with the communication hole 9, the partition 3a without the communication hole The tank 4 and the outer tank 5 are separated.

  In the present embodiment, the inside of the outer tub 5 is separated from the inside of the inner tub 4 by using the partition wall 3a having no communication hole.

  The outer tub 5 is filled with a small piece of the solid heat storage material 7 similar to that shown in FIG. 1 and a molten salt heat storage material 21 for filling a gap between the small pieces of the solid heat storage material 7.

  As the molten salt heat storage material 21 in the outer tub 5, a material that undergoes a solid-liquid phase change in the heat storage temperature range may be used, similarly to the phase change heat storage material 6 in the configuration of the embodiment of FIG. 1. . In this case, the molten salt heat storage material 21 may be the same as the phase change heat storage material 6 filled in the inner tank 4, for example. According to this configuration, the heat storage and heat retaining layer 8 formed in the outer tub 5 can store heat using latent heat when the molten salt heat storage material 21 undergoes a solid-liquid phase change, and thus increases the heat storage density. be able to.

  Alternatively, when the molten salt heat storage material 21 in the outer tub 5 mainly fills the gaps between the small pieces of the solid heat storage material 7 and reduces the thermal resistance between the small pieces, the heat storage temperature You may make it use what becomes a liquid phase in the whole range.

  Other configurations are the same as those shown in FIG. 1, and the same components are denoted by the same reference numerals.

  The heat storage system 1A of the present embodiment configured as described above can be used in the same manner as the heat storage system 1 of the embodiment of FIG.

  Next, FIG. 3 shows still another embodiment of the present invention.

  As shown in FIG. 3, the heat storage system 1 </ b> B of the present embodiment is replaced with a configuration in which the outer tub 5 is filled with small pieces of the solid heat storage material 7 and the molten salt heat storage material 21 in the same configuration as shown in FIG. 2. Thus, only the solid heat storage material 22 is stored in the outer tub 5.

  In this case, in order to increase the efficiency of heat transfer between the solid heat storage material 22 and the phase change heat storage material 6 in the inner tank 4 via the partition wall 3a, the solid heat storage material 22 and the partition wall 3a It is desirable to reduce the thermal resistance by eliminating the gap between the outer peripheral surface. In addition, it is desirable that there are no gaps that generate thermal resistance in the vertical direction of the solid heat storage material 22.

  Therefore, the solid heat storage material 22 is molded into a cylindrical integrated body having an inner diameter corresponding to the outer diameter of the partition wall 3a or a segment obtained by dividing the cylindrical shape into a plurality of segments only in the circumferential direction, and the partition wall 3a is arranged in close contact with the outer peripheral surface.

  Other configurations are the same as those shown in FIG. 1, and the same components are denoted by the same reference numerals.

  The heat storage system 1B of the present embodiment having the above configuration can be used in the same manner as the heat storage system 1 of the embodiment of FIG. 1 to obtain the same effect.

  In addition, this invention is not limited only to the said embodiment, The vertical dimension and diameter dimension of the thermal storage tank 2 shown in each figure, the diameter dimension and thickness dimension of the partition 3, 3a, and provided in the partition 3 The size and arrangement of the communication holes 9, the thickness of the heat transfer tube 16, and the dimensions of each other part are for convenience of illustration, and do not reflect actual dimensions.

  The heating medium supply line 14 and the heating medium return line 15 connected to the heating medium flow path 12 of the hot plate 10 are not arranged such that either one or both of them pass through the inside of the heat storage tank 2, The hot plate 10 may be connected directly from the side or from below.

  The hot plate 10 provided at the lower end of the heat storage tank 2 may be configured such that a heat transfer tube for making a heat medium flow path is directly attached to the lower surface side of the plate member 11 and the heating medium 13 is circulated through the heat transfer tube. Good.

  Furthermore, when the heat storage system 1, 1A, 1B of the present invention is used for the purpose of heat storage of power generated by a power generator using natural energy or other power, an electric heater is used as the hot plate 10. It is good also as a structure.

  The arrangement of the heat transfer tubes 16 at the upper position of the inner tank 4 may be any arrangement other than that illustrated in accordance with the size and shape of the inner tank 4 provided in the heat storage tank 2.

  As the heat storage material 6 for phase change, it is preferable to use the exemplified non-eutectic composition binary mixed salt, but it causes a solid-liquid phase change in a predetermined heat storage temperature range, and a solid phase. If the density of the liquid is higher than the density of the liquid phase, a single component salt (molten salt), a mixed salt of three or more components of a non-eutectic composition, a mixed salt of a plurality of components of a eutectic composition, other than salts Any heat storage material may be used.

  The heat storage temperature range may be freely changed according to the type of heat source and heat load.

  The inner tank 4 may be configured to include a solid phase peeling means for forcibly peeling the solid phase of the phase change heat storage material 6 attached to the surface of the heat transfer tube 16.

  Of course, various modifications can be made without departing from the scope of the present invention.

1, 1A, 1B heat storage system, 2 heat storage tank, 3, 3a partition wall, 4 inner tank, 5 outer tank, 6 phase change heat storage material, 7 solid heat storage material, 9 communication hole, 10 hot plate, 16 heat transfer tube, 20 Partition heater, 21 Molten salt heat storage material, 22 Solid heat storage material

Claims (3)

A heat storage tank comprising a partition wall extending in the circumferential direction at a position near the outer periphery in the tank, an inner area of the partition wall as an inner tank, and an outer area as an outer tank,
A phase change heat storage material filled in the inner tank, causing a solid-liquid phase change in a preset heat storage temperature range, and having a solid phase density larger than the liquid phase density, and
A solid heat storage material filled in the outer tub and serving as a solid phase in the heat storage temperature range;
At the lower end of the heat storage tank, provided at the bottom of the inner tank and the outer tank, a hot plate that heats the heat storage material for heat storage,
A heat transfer tube for taking out the heat held by the phase change heat storage material;
A heat storage system comprising: a partition wall heater configured to heat the partition wall to a solid-liquid phase change temperature of the phase change heat storage material. The outer tank of the heat storage tank is filled with a solid heat storage material in the form of small pieces,
The partition wall of the heat storage tank is provided with a communication hole that blocks the passage of the small pieces of the solid heat storage material and allows the liquid phase of the phase change heat storage material to pass through, so that the inner tank and the outer tank communicate with each other.
The heat storage system according to claim 1, wherein a part of the phase change heat storage material is moved from the inner tank to the outer tank through the communication hole of the partition wall to fill a gap between the small pieces of the solid heat storage material. The outer tank of the heat storage tank is filled with a solid heat storage material in the form of small pieces,
The heat storage system according to claim 1, wherein a gap between the small pieces of the solid heat storage material in the outer tank is filled with a molten salt heat storage material.

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