Heat storage system

Abstract

In a heat storage system including a plurality of heat storage units that store a heat medium heated by a heat collection unit, and a heat utilization unit that lowers a temperature of the heat medium stored in the heat storage units by using heat of the heat medium stored in the plurality of heat storage units, when heat radiation target switching control for sequentially switching and setting a heat radiation target to the plurality of heat storage units according to a heat storage temperature is executed, a significant temperature rise of the heat medium in the heat utilization unit is suppressed.SOLUTION: In the heat radiation target switching control in which the heat radiation target switching units 2a to 2c are controlled based on the detection results of the heat storage temperature detection units 3A to 3F, and the heat radiation target Y is sequentially switched and set to the plurality of heat storage units 1A to 1F according to the heat storage temperature t2, the heat radiation target Y is switched before the heat storage temperature 1F of the heat storage units 1A to set to the heat radiation target Y decreases to a predetermined heat radiation completion heat storage temperature when it is determined that the heat radiation is completed. t2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat storage system including a plurality of heat storage units that store a heat medium heated in a heat collection unit, and a heat utilization unit that uses the heat of the heat medium stored in the plurality of heat storage units to lower the temperature of the heat medium stored in the heat storage units. [Background technology]

[0002] A heat storage system is known in which solar heat collected by a solar heat collection unit (an example of a heat collection unit) is stored in the heat storage unit as the temperature of the heat medium stored in the heat storage unit increases, and the heat stored in the heat storage unit is released to a heat utilization unit as the temperature of the heat medium stored in the heat storage unit decreases (see, for example, Patent Document 1). The heat storage system described in Patent Document 1 is configured to store heat collected by a solar heat collection unit, which fluctuates greatly depending on weather and other factors, in multiple small-capacity heat storage units, rather than storing it in a single large-capacity heat storage unit.With this configuration, even if the amount of solar heat collected by the solar heat collection unit is small, the temperature of the heat medium stored in some of the heat storage units can be sufficiently increased, thereby solving the problem of insufficient temperature of the heat medium used in the heat utilization unit.Also, even if the amount of solar heat collected by the solar heat collection unit is large, the heat can be stored in multiple heat storage units with sufficient heat storage capacity, solving the problem of insufficient heat storage capacity.

[0003] The heat storage system described in Patent Document 1 is provided with a heat storage target switching unit (four-way valve 10) that can switch the heat storage target to which the heat medium is supplied from the solar heat collection unit for the multiple heat storage units, and a heat dissipation target switching unit (four-way valve 13) that can switch the heat dissipation target to which the heat medium is supplied to the heat utilization unit for the multiple heat storage units.These heat storage target switching units and heat dissipation target switching units are controlled based on the detection results of a heat storage temperature detection unit that detects the temperature of the heat medium stored in each of the multiple heat storage units as the heat storage temperature, so that the heat storage target and heat dissipation target for the multiple heat storage units are sequentially switched and set according to the heat storage temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 58-159448 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional heat storage system with multiple heat storage units, a heat dissipation target is sequentially selected for the multiple heat storage units according to the heat storage temperature. Generally, when the heat storage temperature of the heat storage unit selected as the heat dissipation target drops to a predetermined heat dissipation completion temperature at which heat dissipation is determined to be complete, the heat dissipation target is switched to another heat storage unit storing a relatively high-temperature heat medium. When the heat dissipation target is switched, the temperature of the heat medium supplied to the heat utilization unit rises significantly in a short period of time from the relatively low heat dissipation completion heat storage temperature. This rapid and significant temperature rise of the heat medium supplied to the heat utilization unit can cause discomfort to users. In view of this situation, the main object of the present invention is to provide a technology for suppressing a significant temperature rise of the heat medium in the heat utilization unit when performing heat dissipation target switching control in a heat storage system that includes a plurality of heat storage units that store a heat medium heated in a heat collection unit, and a heat utilization unit that uses the heat of the heat medium stored in the plurality of heat storage units to lower the temperature of the heat medium stored in the heat storage units, in which the heat dissipation target is sequentially switched and set for the plurality of heat storage units according to the heat storage temperature. [Means for solving the problem]

[0006] A first characteristic configuration of the present invention is a heat transfer device including a plurality of heat storage units for storing a heat medium heated by a heat collecting unit; a heat utilization unit that utilizes heat of the heat medium stored in the plurality of heat storage units to lower the temperature of the heat medium stored in the heat storage units, a heat dissipation target switching unit that can switch a heat dissipation target that serves as a supply source of heat medium to the heat utilization unit for the plurality of heat storage units; a heat storage temperature detection unit that detects the temperature of the heat medium stored in each of the plurality of heat storage units as a heat storage temperature; an operation control unit that controls the heat dissipation target switching unit based on a detection result of the heat storage temperature detection unit, and executes heat dissipation target switching control to sequentially switch and set the heat dissipation target for the plurality of heat storage units according to the heat storage temperature, The operation control unit, in the heat dissipation target switching control, switches the heat dissipation target before the heat storage temperature of the heat storage unit set as the heat dissipation target drops to a predetermined heat dissipation completion heat storage temperature at which it is determined that heat dissipation is complete.

[0007] According to this configuration, when heat dissipation target switching control is executed to sequentially switch and set the heat dissipation target for a plurality of heat storage units according to the heat storage temperature, the heat dissipation target is switched before the heat storage temperature of the heat storage unit set as the heat dissipation target drops to a predetermined heat dissipation completion heat storage temperature at which heat dissipation is determined to be complete. This makes it possible to reduce the temperature rise of the heat medium supplied to the heat utilization unit at the time of switching the heat dissipation target, compared to when the heat dissipation target is switched when the heat storage temperature of the heat storage unit set as the heat dissipation target drops to the heat dissipation completion heat storage temperature. Therefore, according to the present invention, in a heat storage system having a plurality of heat storage sections that store a heat medium heated in a heat collection section, and a heat utilization section that uses the heat of the heat medium stored in the plurality of heat storage sections to lower the temperature of the heat medium stored in the heat storage sections, a technology can be provided for suppressing a significant temperature rise of the heat medium in the heat utilization section when performing heat dissipation target switching control that sequentially switches and sets the heat dissipation target for the plurality of heat storage sections according to the heat storage temperature.

[0008] A second characteristic feature of the present invention is that the heat collection section is a solar heat collection section that absorbs solar heat and heats the heat medium.

[0009] According to this configuration, the solar heat collected by the solar heat collection unit, which fluctuates greatly depending on the weather, is stored in multiple small-capacity heat storage units rather than in a single large-capacity heat storage unit. With this configuration, even if the amount of solar heat collected by the solar heat collection unit is small, the temperature of the heat medium stored in some of the heat storage units can be sufficiently increased, thereby eliminating the problem of insufficient temperature of the heat medium used in the heat utilization unit. Furthermore, even if the amount of solar heat collected by the solar heat collection unit is large, the heat can be stored in multiple heat storage units with sufficient heat storage capacity, eliminating the problem of insufficient heat storage capacity. When storing the solar heat collected by the solar heat collector in multiple heat storage units in this manner, as described above, heat dissipation target switching control is performed to switch the heat dissipation target before the heat storage temperature of the heat storage unit drops to the heat dissipation completion heat storage temperature, thereby making it possible to appropriately utilize the solar heat while suppressing a significant temperature increase of the heat medium in the heat utilization unit.

[0010] A third characteristic configuration of the present invention is that, in the heat dissipation target switching control, the operation control unit switches the heat dissipation target so that the temperature decrease range of the heat storage temperature of the heat storage unit currently set as the heat dissipation target relative to the heat storage temperature of the heat storage unit that will be set as the heat dissipation target next does not exceed a predetermined allowable temperature difference.

[0011] According to this configuration, when heat dissipation target switching control is executed to sequentially switch and set the heat dissipation target for a plurality of heat storage units according to the heat storage temperature, the heat dissipation target is switched before the temperature drop in the heat storage temperature of the heat storage unit currently set as the heat dissipation target from the heat storage temperature of the heat storage unit set as the next heat dissipation target exceeds a predetermined allowable temperature difference, thereby making it possible to appropriately reduce the temperature rise in the heat medium supplied to the heat utilization unit at the time of switching the heat dissipation target.

[0012] A fourth characteristic configuration of the present invention includes a heat storage target switching unit that can switch a heat storage target to which the heat medium is supplied from the heat collection unit to the plurality of heat storage units, the operation control unit controls the heat storage target switching unit based on the detection result of the heat storage temperature detection unit, and executes heat storage target switching control to sequentially switch and set the heat storage target for the plurality of heat storage units according to the heat storage temperature; The operation control unit, in the heat storage target switching control, switches the heat storage target in a predetermined heat storage target switching order, and executes a heat storage target switching order change process that changes the heat storage target switching order depending on the state of the heat storage unit.

[0013] According to this configuration, when executing heat storage target switching control that sequentially switches and sets the heat storage target for the multiple heat storage units according to the heat storage temperature, the heat collected by the heat collection unit can be stored in the multiple heat storage units by switching the heat storage target according to a predetermined heat storage target switching order. Then, this heat storage target switching order can be changed according to the state of the heat storage units, and an appropriate heat storage unit can be determined as the next heat storage target. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing the configuration of a heat storage system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram illustrating the timing of switching the heat storage target in accordance with the heat storage temperature in each heat storage unit in the heat storage target switching control. [Figure 3] FIG. 10 is a diagram illustrating the timing of switching the heat dissipation target in accordance with the heat storage temperature in each heat storage unit in the heat dissipation target switching control. [Figure 4] FIG. 10 is a diagram illustrating the timing of switching the heat dissipation target in accordance with the heat storage temperature in each heat storage unit in the heat dissipation target switching control. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the heat storage system of this embodiment (hereinafter referred to as "this heat storage system") comprises a plurality of sealed hot water storage tanks 1A, 1B, 1C, 1D, 1E, 1F (an example of a heat storage unit) that store hot water (an example of a heat medium) heated by a solar heat collector 10 (an example of a heat collector), a heat utilization unit 35 such as a hot water supply unit such as a hot water tap or a bathtub or a heat dissipation unit such as a hot water heating device that uses the heat of the heat medium stored in the plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, 1F to lower the heat storage temperature t2, which is the temperature of the hot water stored in the hot water storage tanks 1A, 1B, 1C, 1D, 1E, 1F, and an operation control unit 50 that controls the operation of various devices. In other words, this heat storage system is configured to store solar heat collected by the solar heat collection section 10 in hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F as the heat storage temperature t2 increases, and to dissipate the heat stored in the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to the heat utilization section 35 as the heat storage temperature t2 decreases. In this embodiment, the number of installed solar heat collectors 10 is four, but the number can be changed as appropriate. Also, in this embodiment, the number of installed hot water tanks 1A, 1B, 1C, 1D, 1E, and 1F is six, but the number can be changed as appropriate as long as it is plural. In FIG. 1, open valves are shown in white, closed valves are shown in black, and arrows on each pipe indicate the flow direction of the heat transfer medium and hot water.

[0016] Furthermore, this heat storage system stores the heat collected by solar heat collection unit 10, which fluctuates greatly depending on the weather, etc., in multiple small-capacity hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, rather than storing it in a single large-capacity hot water storage tank. This makes it possible to sufficiently increase the heat storage temperature t2 in some of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F even when the amount of solar heat collected by solar heat collection unit 10 is small, thereby eliminating the problem of insufficient hot water temperature used in heat utilization unit 35. Furthermore, even when the amount of solar heat collected by solar heat collection unit 10 is large, the heat can be stored in multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, which have sufficient heat storage capacity, thereby eliminating the problem of insufficient heat storage capacity.

[0017] The solar heat collection section 10 is provided with a plurality of solar heat collection panels 11 that collect solar heat, a heat collection circulation circuit 15 that circulates a heat collection heat medium to each solar heat collection panel 11, and a heat exchanger 19 that exchanges heat between the heat collection heat medium flowing through the heat collection circulation circuit 15 and hot water flowing through a heat storage circulation circuit 25 described later.

[0018] Furthermore, the heat collection circulation circuit 15 has a plurality of solar thermal collection panels 11 connected in parallel, and is provided with a heat collection forward piping 16 that sends the heat collection medium discharged from the heat exchanger 19 to each solar thermal collection panel 11, and a heat collection return piping 17 that sends the heat collection medium discharged from each solar thermal collection panel 11 to the heat exchanger 19. That is, by operation of a circulation pump 18 provided in the heat collection circulation circuit 15, the heat collection medium at a relatively low temperature, which has passed through the heat exchanger 19 and lost heat through heat exchange with hot water in a heat storage circulation circuit 25 described below, is introduced into each solar thermal collection section 10 through the heat collection forward piping 16. At the same time, the heat collection medium at a relatively high temperature, which has passed through the solar thermal collection section 10 and been heated by solar heat, is introduced into the heat exchanger 19 through the heat collection return piping 17. Therefore, in the heat exchanger 19, the hot water flowing through the heat storage circulation circuit 25 described later is heated by heat exchange with the heat collection heat medium which has become hot by absorbing the solar heat collected by each solar heat collection panel 11. The heat collection supply pipe 16 is provided with a heat collection supply temperature sensor 12 that detects, as a heat collection supply temperature t12, the temperature of the relatively low-temperature heat collection medium supplied from the heat exchanger 19 to the solar heat collection panel 11. On the other hand, the heat collection return pipe 17 is provided with a heat collection return temperature sensor 13 that detects, as a heat collection return temperature t13, the temperature of the heat collection medium sent from the solar heat collection panel 11 to the heat exchanger 19. The temperatures t12 and t13 detected by these temperature sensors 12 and 13 are input to the operation control unit 50.

[0019] Furthermore, this heat storage system is provided with a heat storage circulation circuit 25 through which hot water circulates between the heat exchanger 19 of the solar heat collection section 10 and the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, and a heat dissipation circulation circuit 30 through which hot water circulates between the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F and the heat utilization section 35.

[0020] A plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F are connected in parallel to the heat storage circulation circuit 25, and are provided with a heat storage forward pipe 26 that sends hot water discharged from the heat exchanger 19 to the top 1a of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, and a heat storage return pipe 27 that sends hot water discharged from the bottom 1b of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to the heat exchanger 19. That is, by operating a circulation pump 28 provided in the heat storage circulation circuit 25, relatively high-temperature hot water that has passed through the heat exchanger 19 and been heated by heat exchange with the heat collection heat medium of the heat collection circulation circuit 15 is introduced through the heat storage forward pipe 26 into the top 1a of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F. At the same time, relatively low temperature hot water discharged from the bottoms 1b of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F is introduced into the heat exchanger 19 through the heat storage return pipe 27. As a result, in the sealed hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, the solar heat collected by the solar heat collector 10 can be stored inside the tank in a manner that increases the amount of hot water in the upper high-temperature layer and decreases the amount of hot water in the lower low-temperature layer, while maintaining a temperature stratification consisting of an upper high-temperature layer where high-temperature hot water is stored and a lower low-temperature layer where low-temperature hot water is stored.

[0021] Furthermore, at the connection points of each hot water storage tank 1A, 1B, 1C, 1D, 1E, 1F to the heat storage supply pipe 26, there are provided heat storage side opening / closing control valves 2A, 2B, 2C, 2D, 2E, 2F which can interrupt the supply of hot water from the heat storage supply pipe 26 to the hot water storage tanks 1A, 1B, 1C, 1D, 1E, 1F, and these are controlled to open and close by the operation control unit 50. By selectively opening the heat-storage-side on-off control valves 2A, 2B, 2C, 2D, 2E, and 2F, the operation control unit 50 can set the hot water tanks 1A, 1B, 1C, 1D, 1E, and 1F (hot water storage tank 1D in the example shown in FIG. 1) corresponding to the opened heat-storage-side on-off control valves 2A, 2B, 2C, 2D, 2E, and 2F (heat-storage-side on-off control valve 2D in the example shown in FIG. 1) as the heat storage target X to which hot water is supplied from the heat exchanger 19 of the solar thermal collector 10 through the heat-storage supply pipe 26, accompanied by the extraction of hot water from the bottom 1b to the heat-storage return pipe 27. Then, in the hot water storage tank (hot water storage tank 1D in the example shown in FIG. 1) set as the heat storage target X, the relatively high-temperature hot water heated by the heat exchanger 19 is introduced from the top 1a, and the relatively low-temperature hot water is extracted from the bottom 1b, so that the heat storage temperature t2 rises. In other words, these heat storage side opening / closing control valves 2A, 2B, 2C, 2D, 2E, and 2F function as heat storage target switching units that can switch the heat storage target X to which hot water is supplied from the heat exchanger 19 of the solar heat collector 10 to multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F.

[0022] Furthermore, the operation control unit 50 is configured to perform a heat storage operation in which the solar heat collected by the solar heat collection unit 10 is stored in the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F only when the heat collection return temperature t13 is equal to or higher than a predetermined heat storage operation start temperature (e.g., t2 + 10°C) based on the heat storage temperature t2 of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F. Also, the operation control unit 50 is configured to stop the heat storage operation when the heat collection return temperature t13 drops to a predetermined heat storage operation stop temperature (e.g., t2 + 5°C) based on the heat storage temperature t2 of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F during the heat storage operation.

[0023] A plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F are connected in parallel to the heat radiation circulation circuit 30, and is provided with a heat radiation forward pipe 31 that sends hot water dispensed from the top 1a of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to the heat utilization section 35, and a heat radiation return pipe 32 that sends hot water dispensed from the heat utilization section 35 to the bottom 1b of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F. A water supply pipe 39 is connected to the heat radiation return pipe 32 to replenish the hot water consumed in the heat utilization section 35. That is, by the operation of a circulation pump (not shown) provided on the heat utilization section 35 side of the heat radiation circulation circuit 30 and the consumption of hot water in the heat utilization section 35, relatively high temperature hot water discharged from the top 1a of each hot water storage tank 1A, 1B, 1C, 1D, 1E, 1F is supplied to the heat utilization section 35 through the heat radiation forward pipe 31. At the same time, relatively low temperature hot water discharged from the heat utilization section 35 or relatively low temperature hot water replenished from the water supply pipe 39 is introduced through the heat radiation return pipe 32 into the bottom 1b of each hot water storage tank 1A, 1B, 1C, 1D, 1E, 1F. As a result, the sealed hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F can dissipate the heat stored inside to the heat utilization section 35 by reducing the amount of hot water in the upper high-temperature layer and increasing the amount of hot water in the lower low-temperature layer while maintaining the above-mentioned temperature stratification. The hot water discharged from the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to the heat dissipation pipeline 31 may be supplied to the heat utilization section 35 as is, or it may be supplied to the heat utilization section 35 after adjusting the temperature appropriately by mixing it with low-temperature feed water or heating it with an auxiliary heat source.

[0024] Furthermore, at the connection points of each hot water storage tank 1A, 1B, 1C, 1D, 1E, 1F to the heat radiation return pipe 32, heat radiation side opening / closing control valves 3A, 3B, 3C, 3D, 3E, 3F are provided which can interrupt the supply of hot water from the heat radiation return pipe 32 to the hot water storage tanks 1A, 1B, 1C, 1D, 1E, 1F, and these are controlled to open and close by the operation control unit 50. By selectively opening the heat dissipation side on-off control valves 3A, 3B, 3C, 3D, 3E, 3F, the operation control unit 50 can set the hot water tanks 1A, 1B, 1C, 1D, 1E, 1F (hot water storage tank 1A in the example shown in FIG. 1) corresponding to the opened heat dissipation side on-off control valves 3A, 3B, 3C, 3D, 3E, 3F (heat dissipation side on-off control valve 3A in the example shown in FIG. 1) as heat dissipation target Y, which is the supply source of hot water through the heat dissipation forward pipe 31 to the heat utilization unit 35, accompanied by the introduction of hot water from the heat dissipation return pipe 32 to the bottom 1b. Then, in the hot water storage tank set as the heat dissipation target Y (hot water storage tank 1A in FIG. 1), relatively low-temperature hot water is introduced from the bottom 1b and relatively high-temperature hot water is drawn out from the top 1a, so that the heat storage temperature t2 drops. In other words, these heat dissipation side opening / closing control valves 3A, 3B, 3C, 3D, 3E, and 3F function as heat dissipation target switching units that can switch the heat dissipation target Y that is the source of hot water supplied to the heat utilization unit 35 for multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F.

[0025] Each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F is provided with a heat storage temperature detector for detecting the heat storage temperature t2, which includes an upper heat storage temperature sensor 2a that detects the heat storage temperature t2a on the upper side near the top 1a, a middle heat storage temperature sensor 2b that detects the heat storage temperature t2b in the middle between the top and bottom, and a lower heat storage temperature sensor 2c that detects the heat storage temperature t2c on the lower side near the bottom 1b. The heat storage temperatures t2a, t2b, and t2c detected by these heat storage temperature sensors 2a, 2b, and 2c are input to the operation control unit 50. In this embodiment, the operation control unit 50 is configured to recognize the heat storage temperature t2b at the middle part of the upper and lower sides, among the heat storage temperature t2a at the upper side, the heat storage temperature t2b at the middle part of the upper and lower sides, and the heat storage temperature t2c at the lower side, as the heat storage temperature t2, which is the temperature of the hot water stored in the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, but it may also be configured to recognize the heat storage temperature t2a at the upper side or the heat storage temperature t2c at the lower side as the heat storage temperature t2.

[0026] The operation control unit 50 executes a predetermined computer program to function as a heat storage target switching control means 51 that executes heat storage target switching control to sequentially switch and set the heat storage target X to an appropriate state according to the heat storage temperature t2, and a heat dissipation target switching control means 52 that executes heat dissipation target switching control to sequentially switch and set the heat dissipation target Y to an appropriate state according to the heat storage temperature t2. The heat storage target switching control executed by the heat storage target switching control means 51 and the heat dissipation target switching control executed by the heat dissipation target switching control means 52 will be described in detail below.

[0027] [Heat storage target switching control] The heat storage target switching control is executed by a heat storage target switching control means 51, which controls the heat storage side opening / closing control valves 2A, 2B, 2C, 2D, 2E, and 2F, which are heat storage target switching units, based on the detection results of the heat storage temperature sensors 2a, 2b, and 2c, which are heat storage temperature detection units, to sequentially switch and set the heat storage target X for the multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F according to the heat storage temperature t2. Furthermore, in the heat storage target switching control, the heat storage target X is switched in accordance with a predetermined heat storage target switching order, and a heat storage target switching order change process is executed to change the heat storage target switching order depending on the state of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F.

[0028] That is, when heat storage target switching control is executed to sequentially switch and set the heat storage target X for the plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F according to the heat storage temperature t2, the heat collected by the solar heat collector 10 can be stored in the plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F by switching the heat storage target X according to the heat storage target switching order. Then, this heat storage target switching order can be changed according to the states of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, and an appropriate hot water storage tank 1A, 1B, 1C, 1D, 1E, and 1F can be determined as the next heat storage target X1 (see FIG. 2).

[0029] A specific example of a method for switching the heat storage target X by the heat storage target switching control will be described with reference to FIG. 2 shows how the heat storage temperature t2 of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F changes in the order of (a), (b), and (c). In addition, in FIG. 2, the hot water storage tank designated with the symbol X is the hot water storage tank set as the heat storage target X at that time, and the hot water storage tank designated with the symbol X1 is the hot water storage tank set as the heat storage target X at the next time. In this embodiment, the hot water storage tank 1C is set as the heat release target Y.

[0030] In this embodiment, the heat storage target switching order, which indicates the switching order of the heat storage target X, is predetermined to be in the order of hot water storage tank 1A, followed by hot water storage tank 1B, then hot water storage tank 1C, then hot water storage tank 1D, then hot water storage tank 1E, then hot water storage tank 1F, and then hot water storage tank 1A. In the heat storage target switching order change process described above, the hot water storage tank set as the heat dissipation target Y (hot water storage tank 1C in Figure 2) is not set as the heat storage target X, and by changing the heat storage target switching order, it is possible to avoid each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F being set as both the heat dissipation target Y and the heat storage target X at the same time. Furthermore, in the heat storage target switching order change process, the heat storage target switching order is changed in a periodically rotating manner, thereby suppressing uneven wear of the heat storage side opening / closing control valves 2A, 2B, 2C, 2D, 2E, and 2F, whose operation is controlled in accordance with the switching of the heat storage target X.

[0031] As shown in (a) of Figure 2, it is assumed that the hot water storage tank 1A is set as the heat storage target X. Then, the heat storage temperature t2 of the hot water storage tank 1A rises. At this time, according to the heat storage target switching order, the hot water storage tank 1B is set as a candidate for the next heat storage target X1.

[0032] Next, when the heat storage temperature t2 of the hot water storage tank 1A set as the heat storage target X reaches a preset heat storage completion heat storage temperature TH (for example, 80°C), the heat storage target X is switched to the hot water storage tank 1B, as shown in (b) of FIG. 2. Then, the heat storage temperature t2 of the hot water storage tank 1B rises. At this time, according to the heat storage target switching order, the hot water storage tank 1C should be set as the next heat storage target X1, but since the hot water storage tank 1C is set as the heat release target Y, it is skipped, and the hot water storage tank 1D is set as a candidate for the next heat storage target X1 based on the heat storage target switching order.

[0033] Next, when the heat storage temperature t2 of the hot water storage tank 1B set as the heat storage target X reaches a preset heat storage completion heat storage temperature TH (e.g., 80°C), the heat storage target X is switched to the hot water storage tank 1D as shown in FIG. 2(c). Then, the heat storage temperature t2 of the hot water storage tank 1D rises. At this time, according to the heat storage target switching order, the hot water storage tank 1E is selected as a candidate for the next heat storage target X1. In this way, by executing heat storage target switching control for the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F and switching the heat storage target X, the solar heat collected by the solar heat collector 10 can be stored in each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F in a manner that raises the heat storage temperature t2 of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to the heat storage completion heat storage temperature TH.

[0034] [Heat dissipation target switching control] The heat dissipation target switching control is executed by a heat dissipation target switching control means 52, which controls the heat dissipation side opening / closing control valves 3A, 3B, 3C, 3D, 3E, and 3F, which are heat dissipation target switching units, based on the detection results of the heat storage temperature sensors 2a, 2b, and 2c, which are heat storage temperature detection units, to sequentially switch and set the heat dissipation target Y for the multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F according to the heat storage temperature t2. Furthermore, in the heat dissipation target switching control, the heat dissipation target Y is switched in accordance with a predetermined heat dissipation target switching order, and a heat dissipation target switching order change process is executed to change the heat dissipation target switching order depending on the state of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F.

[0035] That is, when heat dissipation target switching control is executed to sequentially switch and set the heat dissipation target Y for the multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F according to the heat storage temperature t2, the heat dissipation target Y is switched in accordance with the heat dissipation target switching order, so that the heat stored in the multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F can be dissipated to the heat utilization unit 35. Then, this heat dissipation target switching order can be changed according to the states of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, and an appropriate hot water storage tank 1A, 1B, 1C, 1D, 1E, and 1F can be determined as the next heat dissipation target Y1 (see FIGS. 3 and 4).

[0036] A specific example of a method for switching the heat dissipation target Y by the heat dissipation target switching control will be described with reference to FIGS. 3 and 4 show how the heat storage temperature t2 of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F changes in the order of (a), (b), and (c). In addition, in Fig. 3 and Fig. 4, the hot water storage tank designated with the symbol Y is the hot water storage tank set as the heat release target Y at that time, and the hot water storage tank designated with the symbol Y1 is the hot water storage tank set as the heat release target Y at the next time. In this embodiment, the hot water storage tank 1D is set as the heat storage target X. In this embodiment, when performing the heat dissipation target switching control, it is initially assumed that the heat storage temperature t2 of the hot water storage tanks 1A, 1B, and 1C is the heat storage completion heat storage temperature TH (e.g., 80°C), and that the heat storage temperatures t2 of the other hot water storage tanks 1D, 1E, and 1F are temperatures lower than the heat storage completion heat storage temperature TH (e.g., 60°C).

[0037] In this embodiment, the heat dissipation target switching order indicating the switching order of the heat dissipation targets Y is predetermined so that the heat dissipation targets Y are selected in descending order of the heat storage temperature t2. In the above-mentioned heat dissipation target switching order change process, the hot water storage tank set as the heat storage target X (hot water storage tank 1D in Figures 3 and 4) is not set as the heat dissipation target Y, and by changing the heat dissipation target switching order, it is possible to avoid each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F being set as both the heat storage target X and the heat dissipation target Y at the same time.

[0038] 3(a), first, assume that the hot water storage tank 1A, which has the highest heat storage temperature t2, for example, the heat storage completion heat storage temperature TH, is set as the heat release target Y. Then, the heat storage temperature t2 of the hot water storage tank 1A drops. At this time, according to the heat release target switching order, the hot water storage tank 1B, which has the highest heat storage temperature t2, the heat storage completion heat storage temperature TH, is set as a candidate for the next heat release target Y1.

[0039] Next, before the heat storage temperature t2 of the hot water storage tank 1A set as the heat release target Y drops to a predetermined heat release completion heat storage temperature TL (for example, 45°C) at which it is determined that heat release is complete, the heat release target Y is switched to the hot water storage tank 1B as shown in (b) of Fig. 3. Specifically, when the temperature decrease width Δta of the heat storage temperature t2 of the hot water storage tank 1A set as the current heat release target Y with respect to the heat storage temperature t2 of the hot water storage tank 1B set as a candidate for the next heat release target Y1 (corresponding to the heat storage completion heat storage temperature TH in (a) of Fig. 3) reaches a predetermined allowable temperature difference ΔTa so as not to exceed the allowable temperature difference ΔTa, the heat release target Y is switched to the hot water storage tank 1B as shown in (b) of Fig. 3. In other words, when the heat storage temperature t2 of the hot water storage tank 1A set as the heat release target Y becomes lower by ΔTa than the heat storage temperature t2 of the hot water storage tank 1B set as the candidate for the next heat release target Y1, the heat release target Y is switched to the hot water storage tank 1B, as shown in Figure 3(b). This causes the heat storage temperature t2 of the hot water storage tank 1B to drop. At this time, according to the heat release target switching order, the hot water storage tank 1C, whose heat storage temperature t2 is the highest at the heat storage completion heat storage temperature TH, is set as the candidate for the next heat release target Y1.

[0040] Before and after switching the heat dissipation target Y, the temperature of the hot water supplied to the heat utilization unit 35 through the heat dissipation outgoing pipe 31 changes from the heat storage temperature t2 of the hot water tank 1A, which is the heat dissipation target Y before the switching, to the heat storage temperature t2 of the hot water tank 1B, which is the heat dissipation target Y after the switching, but the range of this change corresponds to the relatively small allowable temperature difference ΔTa. In other words, compared to when the heat dissipation target Y is switched when the heat storage temperature t2 of the hot water tank 1A, which is set as the heat dissipation target Y, drops to the heat dissipation completion heat storage temperature TL, the range of temperature rise of the hot water supplied to the heat utilization unit 35 at the time of switching the heat dissipation target Y can be appropriately reduced.

[0041] The allowable temperature difference ΔTa may be any temperature range that allows for a rapid change in the temperature of hot water on the heat utilization section 35 side. Furthermore, the allowable temperature difference ΔTa may be set so that the heat stored in the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F is released in stages over multiple times. For example, the allowable temperature difference ΔTa may be set to preferably 10°C or less, more preferably 5°C.

[0042] Next, when the heat storage temperature t2 of the hot water storage tank 1B set as the heat release target Y becomes lower by ΔTa than the heat storage temperature t2 of the hot water storage tank 1C set as the next heat release target Y1, as in the case of switching the heat release target Y from the hot water storage tank 1A to the hot water storage tank 1B described above (switching from (a) to (b) in FIG. 3), the heat release target Y is switched to the hot water storage tank 1C, as shown in (c) in FIG. 3. Then, the heat storage temperature t2 of the hot water storage tank 1C drops. At this time, according to the heat release target switching order described above, the hot water storage tank 1A, which has the highest heat storage temperature t2, is selected as a candidate for the next heat release target Y1.

[0043] Then, until the heat storage temperature t2 of the hot water storage tanks 1A, 1B, 1C drops to the heat storage temperature t2 of the other hot water storage tanks 1D, 1E, 1F, heat release target switching control is executed for the hot water storage tanks 1A, 1B, 1C to switch the heat release target Y. In this way, the heat storage temperature t2 of each of the hot water storage tanks 1A, 1B, 1C is gradually lowered by the above-mentioned allowable temperature difference ΔTa in multiple steps to the heat storage temperature t2 of the other hot water storage tanks 1D, 1E, 1F, and the heat stored in each of the hot water storage tanks 1A, 1B, 1C can be released to the heat utilization unit 35.

[0044] At the point when the heat storage temperatures t2 of the hot water storage tanks 1A, 1B, and 1C have dropped to the same level as the heat storage temperatures t2 of the other hot water storage tanks 1D, 1E, and 1F, it is assumed that the hot water storage tank 1C is first set as the heat release target Y, as shown in FIG. 4(a). Then, the heat storage temperature t2 of the hot water storage tank 1C drops. At this time, according to the heat release target switching order, the hot water storage tank 1D, which is among the tanks with the highest heat storage temperature t2, is selected as a candidate for the next heat release target Y1. However, because the hot water storage tank 1D is set as the heat storage target X, it is skipped, and instead, according to the heat release target switching order, the hot water storage tank 1E, which is among the tanks with the highest heat storage temperature t2, is selected as a candidate for the next heat release target Y1.

[0045] Next, as when the heat dissipation target Y is switched from the hot water storage tank 1A to the hot water storage tank 1B (when switching from (a) to (b) in FIG. 3) as described above, if the heat storage temperature t2 of the hot water storage tank 1C set as the heat dissipation target Y becomes lower by ΔTa than the heat storage temperature t2 of the hot water storage tank 1E selected as the candidate for the next heat dissipation target Y1, the heat dissipation target Y is switched to the hot water storage tank 1E, as shown in (b) in FIG. 4. Then, the heat storage temperature t2 of the hot water storage tank 1E drops. At this time, according to the heat dissipation target switching order, the hot water storage tank 1F with the highest heat storage temperature t2 is selected as the candidate for the next heat dissipation target Y1.

[0046] Before and after switching the heat dissipation target Y, the temperature of the hot water supplied to the heat utilization unit 35 through the heat dissipation outgoing pipe 31 changes from the heat storage temperature t2 of the hot water tank 1C, which is the heat dissipation target Y before the switching, to the heat storage temperature t2 of the hot water tank 1E, which is the heat dissipation target Y after the switching, but the range of this change corresponds to the relatively small allowable temperature difference ΔTa. In other words, compared to when the heat dissipation target Y is switched when the heat storage temperature t2 of the hot water tank 1C, which is set as the heat dissipation target Y, drops to the heat dissipation completion heat storage temperature TL, the range of temperature rise of the hot water supplied to the heat utilization unit 35 at the time of switching the heat dissipation target Y can be appropriately reduced.

[0047] Next, when the heat storage temperature t2 of the hot water storage tank 1E set as the heat release target Y becomes lower by ΔTa than the heat storage temperature t2 of the hot water storage tank 1F set as the next heat release target Y1, as in the case of switching the heat release target Y from the hot water storage tank 1A to the hot water storage tank 1B described above (switching from (a) to (b) in FIG. 3), the heat release target Y is switched to the hot water storage tank 1F, as shown in (c) in FIG. 4. Then, the heat storage temperature t2 of the hot water storage tank 1F drops. At this time, according to the heat release target switching order, the hot water storage tank 1A with the highest heat storage temperature t2 is selected as a candidate for the next heat release target Y1.

[0048] Then, until the heat storage temperature t2 of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F drops to a predetermined heat release completion heat storage temperature TL (for example, 45°C), heat release target switching control is executed for the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F to switch the heat release target Y. In this way, the heat storage temperature t2 of each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F is lowered stepwise by the above-mentioned allowable temperature difference ΔTa multiple times to the heat release completion heat storage temperature TL, and the heat stored in each of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F can be released to the heat utilization unit 35.

[0049] [Another embodiment] Other embodiments of the present invention will be described below. Note that the configurations of the embodiments described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments.

[0050] (1) In this embodiment, the solar heat collected by the solar heat collector 10 is stored in multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F, but it may also be configured to store heat collected by a heat collector other than the solar heat collector 10 in multiple hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F.

[0051] (2) In this embodiment, the heat storage target switching control is executed to sequentially switch and set the heat storage target X for the plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F according to the heat storage temperature t2. However, without switching the heat storage target X in this manner, the heat storage target X may be set to all of the plurality of hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F as the heat storage target X, and the solar heat collected by the solar heat collector 10 may be stored in all of the hot water storage tanks 1A, 1B, 1C, 1D, 1E, and 1F simultaneously. [Explanation of symbols]

[0052] 1A Hot water tank (heat storage section) 1B Hot water tank (thermal storage section) 1C Hot water tank (heat storage section) 1D Hot water tank (thermal storage section) 1E Hot water tank (thermal storage section) 1F hot water tank (thermal storage section) 2A Heat storage side opening / closing control valve (heat storage target switching part) 2B Heat storage side opening / closing control valve (heat storage target switching part) 2C Heat storage side opening / closing control valve (heat storage target switching part) 2D Heat storage side opening / closing control valve (heat storage target switching part) 2E Heat storage side opening / closing control valve (heat storage target switching part) 2F Heat storage side opening / closing control valve (heat storage target switching part) 2a Upper heat storage temperature sensor (heat storage temperature detection part) 2b Intermediate heat storage temperature sensor (heat storage temperature detection part) 2c Lower heat storage temperature sensor (heat storage temperature detection part) 3A Heat dissipation side opening / closing control valve (heat dissipation target switching part) 3B Heat dissipation side opening / closing control valve (heat dissipation target switching part) 3C Heat dissipation side opening / closing control valve (heat dissipation target switching part) 3D Heat dissipation side opening / closing control valve (heat dissipation target switching part) 3E Heat dissipation side opening / closing control valve (heat dissipation target switching part) 3F Heat dissipation side opening / closing control valve (heat dissipation target switching part) 10 Solar heat collector (heat collector) 35 Heat Utilization Department 50 Operation control unit 51 Heat storage target switching control means 52 Heat dissipation target switching control means TH Heat storage completion temperature TL Heat radiation completion heat storage temperature X Heat storage target X1 Next heat storage target Y Heat dissipation target Y1 Next heat dissipation target t2 Heat storage temperature ΔTa Allowable temperature difference Δta Temperature drop width

Claims

1. a plurality of heat storage units that store the heat medium heated by the heat collection units; a heat utilization unit that utilizes heat of the heat medium stored in the plurality of heat storage units to lower the temperature of the heat medium stored in the heat storage units, a heat dissipation target switching unit that can switch a heat dissipation target that serves as a supply source of heat medium to the heat utilization unit for the plurality of heat storage units; a heat storage temperature detection unit that detects the temperature of the heat medium stored in each of the plurality of heat storage units as a heat storage temperature; an operation control unit that controls the heat dissipation target switching unit based on a detection result of the heat storage temperature detection unit, and executes heat dissipation target switching control to sequentially switch and set the heat dissipation target for the plurality of heat storage units according to the heat storage temperature, In the heat dissipation target switching control, the operation control unit switches the heat dissipation target before the heat storage temperature of the heat storage unit set as the heat dissipation target drops to a predetermined heat dissipation completion heat storage temperature at which heat dissipation is determined to be complete.

2. The heat storage system according to claim 1 , wherein the heat collector is a solar heat collector that absorbs solar heat to heat the heat medium.

3. The heat storage system according to claim 1 or 2, wherein the operation control unit switches the heat dissipation target in the heat dissipation target switching control so that the temperature decrease range of the heat storage temperature of the heat storage unit currently set as the heat dissipation target relative to the heat storage temperature of the heat storage unit that will be set as the heat dissipation target next does not exceed a predetermined allowable temperature difference.

4. a heat storage target switching unit that can switch a heat storage target to which the heat medium is supplied from the heat collection unit for the plurality of heat storage units; the operation control unit controls the heat storage target switching unit based on the detection result of the heat storage temperature detection unit, and executes heat storage target switching control to sequentially switch and set the heat storage target for the plurality of heat storage units according to the heat storage temperature; The heat storage system according to claim 1 or 2, wherein the operation control unit, in the heat storage target switching control, switches the heat storage target according to a predetermined heat storage target switching order, and executes a heat storage target switching order change process that changes the heat storage target switching order depending on the state of the heat storage unit.

Images