JP5604190B2 - Heat storage system - Google Patents

Description

  The present invention relates to a heat storage system using a latent heat storage material.

  Conventional heat storage technologies include sensible heat of substances and latent heat storage using latent heat generated when the phase changes from solid to liquid. In latent heat storage, the amount of heat that can be stored is the sum of sensible heat and phase change heat (latent heat), so the heat storage density is larger than heat storage using only sensible heat that stores heated water as it is in a hot water tank. . As a result, the heat storage tank can be reduced in size.

  In latent heat storage, a range of applicable phase change temperatures is determined according to the temperature of the heat source to be used, and a latent heat storage material having a phase change temperature (melting point) within such a range is selected. For example, for a heat source of about 80 to 110 ° C., a hydrate or an inorganic material described in Non-Patent Document 1 can be used as a latent heat storage material. Patent Document 1 proposes a mixed latent heat storage material having a melting point of 34 to 56 ° C.

  On the other hand, as a heat storage system used as a water heater, a heat storage system using a heat pump as a heat source for heating the latent heat storage material is well known (for example, see Patent Document 2). In such a heat storage system, generally, a heat exchanger is provided in a heat storage tank filled with a latent heat storage material. Then, during heat storage, the latent heat storage material is heated and melted by passing high-temperature water heated by a heat pump through the heat exchanger. During heat dissipation, low-temperature water supplied from the water supply pipe is passed through the heat exchanger. Thus, heat is released from the latent heat storage material to the water, and the heated water is distributed to the user side as hot water.

  However, in such a configuration, when the temperature of the heat storage tank rises during heat storage, the temperature of water flowing into the radiator that performs heat exchange between the refrigerant and water in the heat pump increases. For this reason, the amount of heat exchanged in the radiator decreases, and there arises a problem that the heating efficiency of the heat pump decreases.

  In order to solve such a problem, Patent Document 2 proposes a heat storage system 100 as shown in FIG. The heat storage system 100 includes a heat storage circuit 120 that passes through a radiator 111 of a heat pump 110 and a high temperature side heat storage tank 151 and a low temperature side heat storage tank 152 that are separated from each other by a partition wall. The high temperature side heat storage tank 151 contains a high temperature latent heat storage material 161 having a melting point of 50 to 70 ° C., and the low temperature side heat storage tank 152 contains a low temperature latent heat storage material 162 having a melting point of 20 to 40 ° C. Yes. In addition, a water supply pipe 141 and a hot water supply pipe 142 are connected to the heat storage circuit 120.

  At the time of heat storage, the water heated by the radiator 111 of the heat pump circuit 110 exchanges heat with the high-temperature latent heat storage material 161 and then exchanges heat with the low-temperature latent heat storage material 162 and flows into the radiator 111. Thereby, since the temperature of the water which flows into the heat radiator 111 can be made into the melting | fusing point vicinity of the low-temperature latent heat storage material 162, the fall of the heating efficiency of the heat pump circuit 110 can be suppressed.

  At the time of heat dissipation, the water supplied from the water supply pipe 141 exchanges heat with the low-temperature latent heat storage material 162 and then exchanges heat with the high-temperature latent heat storage material 161 and is supplied to the hot water supply pipe 142. Thus, the water whose temperature has risen to some extent by heat exchange with the low-temperature latent heat storage material 162 exchanges heat with the high-temperature latent heat storage material 161, and thus the temperature drop of the high-temperature latent heat storage material 161 is suppressed.

  By the way, in the latent heat storage material, there are many substances that cause a so-called supercooling phenomenon that does not cause a phase change from a liquid to a solid even when cooled to the melting point. FIG. 11 is a graph showing the change over time in the temperature of the heat storage material when the latent heat storage material having a melting point of 56 ° C. containing sodium acetate trihydrate as a main component is cooled. From FIG. 11, it is understood that the supercooled state is maintained until the latent heat storage material is cooled to about 25 ° C. (supercooling release temperature). In addition, immediately after supercooling is cancelled | released, the temperature of a latent-heat storage material rises rapidly to 56 degreeC vicinity which is melting | fusing point.

  Such subcooling of the latent heat storage material is performed, for example, as described in Patent Document 3, by applying a heat medium (water) having a temperature lower than the supercooling release temperature to a part of the latent heat storage material in a supercooled state. It can be released by bringing it into contact.

Special table 2003-507524 gazette Japanese Patent No. 3903804 Japanese Patent No. 3447295

Katsuhiko Narita, Junjiro Kai, “Latent Heat Storage Material”, The Journal of Electrical Engineering, The Institute of Electrical Engineers of Japan, 1981, Vol. 101, No. 1, p. 15-22

  In the heat storage system 100 shown in FIG. 10, when a latent heat storage material that causes a supercooling phenomenon is used, the temperature of the water supplied from the water supply pipe 141 is usually higher than the supercooling release temperature of the low temperature latent heat storage material 162. Therefore, even if supercooling occurs in the low-temperature latent heat storage material 162, the supercooling is released immediately. However, since water heated by the low-temperature latent heat storage material 162 flows into the high-temperature side heat storage tank 151, if supercooling occurs in the high-temperature latent heat storage material 161, the supercooled state of the high-temperature latent heat storage material 161 is low-temperature heat storage. This is maintained until the temperature of the water flowing out of the tank 152 falls below the supercooling release temperature of the high-temperature latent heat storage material 161. That is, the temperature of the high-temperature latent heat storage material 161 continues to decrease for a certain period of time after reaching the melting point, and during that time, hot water having a desired hot-water temperature or higher cannot be taken out from the high-temperature side heat storage tank 151.

  In view of such circumstances, the present invention quickly releases the supercooling even if supercooling occurs in the high melting point side latent heat storage material in a heat storage system using two or more types of latent heat storage materials having different melting points. The purpose is to make it possible.

  In order to solve the above-mentioned problem, the present invention is a heat storage system using two or more types of latent heat storage materials having different melting points, a heat storage tank that individually accommodates each of the latent heat storage materials, and the latent heat storage A flow passage for passing a heat medium that exchanges heat with a material, and passing through the heat storage tank in order of increasing melting point of the latent heat storage material in the heat storage tank, one interposed between the heat storage tanks Alternatively, a flow path having a plurality of communication portions, a supply path for supplying a heat medium to one end on the low melting point side of the latent heat storage material in the flow path, and the other end on the high melting point side of the latent heat storage material in the flow path A distribution path for taking out the heat medium from the supply path, one or a plurality of bypass paths branched from the supply path to each of the connecting portions, and the supply path through the bypass path provided in each of the bypass paths From the above contact And a flow control means to allow or prohibit the flow of heat medium to provide a thermal storage system.

  According to the above configuration, water from the supply path can be directly supplied to the individual heat storage tanks, so even if supercooling occurs in the latent heat storage material on the high melting point side, the supercooling can be performed quickly. Can be released.

The block diagram of the thermal storage system which concerns on 1st Embodiment of this invention. The figure which shows the flow of the refrigerant | coolant and water at the time of the thermal storage driving | operation in the thermal storage system of FIG. The figure which shows the flow of the water of the steady state at the time of the thermal radiation operation in the thermal storage system of FIG. The figure which shows the flow of the water of the 1st bypass state at the time of the thermal radiation operation in the thermal storage system of FIG. The figure which shows the flow of the water of the 2nd bypass state at the time of the thermal radiation operation in the thermal storage system of FIG. The graph showing the transition of the temperature of water flowing out from each heat storage tank during the heat radiation operation in the heat storage system of FIG. The figure which shows the flow of the water of the 1st bypass state at the time of the thermal radiation driving | operation in the thermal storage system which concerns on 2nd Embodiment of this invention. The figure which shows the flow of the water of the 2nd bypass state at the time of the thermal radiation driving | operation in the thermal storage system which concerns on 2nd Embodiment of this invention. The graph showing transition of the temperature of the water which flows out from each heat storage tank at the time of heat radiation operation in the heat storage system concerning a 2nd embodiment of the present invention. Configuration diagram of conventional heat storage system Graph showing transition of temperature of heat storage material relative to cooling time

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a heat storage system 1A according to the first embodiment of the present invention. In this heat storage system 1A, three types of latent heat storage materials 31 to 33 having different melting points are used. However, the kind of the latent heat storage material of the present invention is not limited to three kinds, and may be two kinds or four or more kinds. The heat storage system 1A is used as a hot water heater, and water is used as a heat medium that exchanges heat with the latent heat storage material.

  Specifically, the heat storage system 1A is configured to pass water that extends through the first to third heat storage tanks 21 to 23 and the first to third heat storage tanks 21 to 23 that individually store the latent heat storage materials 31 to 33. The flow path 4 for flowing and the heat storage path 50 which comprises the heat storage circuit 5 with the flow path 4 are provided. Moreover, 1 A of heat storage systems are provided with the heat pump 10 as a heat source for water heating.

  The heat pump 10 has a refrigerant circuit 15 for circulating the refrigerant. The refrigerant circuit 15 includes a compressor 11 that compresses the refrigerant, a radiator (heating means) 12 that radiates the compressed refrigerant and heats the water, an expansion means 13 that expands the radiated refrigerant, and evaporates the expanded refrigerant. An evaporator 14 is included. These devices 11 to 14 are connected in this order by piping. The expansion means 13 may be an expansion valve or an expander that recovers power from the expanding refrigerant. As the refrigerant, carbon dioxide is used in the present embodiment, but R410A or propane, for example, can also be used.

  The heat storage path 50 extends via the radiator 12 of the heat pump 10. The heat storage path 50 is provided with a water supply pump 53 so that water flows from one end to the other end. One end, which is the upstream end of the heat storage path 50, is connected to one end 4 a of the flow path 4 via the first three-way valve 51, and the other end, which is the downstream end of the heat storage path 50, via the second three-way valve 52. And connected to the other end 4 b of the flow passage 4. The first three-way valve 51 is connected to a supply path 71 for supplying water from an unillustrated water source (for example, water supply) to one end 4 a of the flow path 4, and the second three-way valve 52 is connected to the flow path 4. A distribution path 72 is connected to take out water from the other end 4b and distribute it to a hot water tap (not shown).

  The flow passage 4 passes through the first heat storage tank 21, the second heat storage tank 22, and the third heat storage tank 23 in this order from the one end 4a to the other end 4b. The first heat storage tank 21 contains a low-temperature latent heat storage material 31 with the lowest melting point, the third heat storage tank 23 contains a high-temperature latent heat storage material 33 with the highest melting point, and the second heat storage tank 22 contains A medium-temperature latent heat storage material 32 having a melting point between them is accommodated. In other words, the flow passage 4 passes through the first to third heat storage tanks 21 to 23 in order from the lowest melting point of the latent heat storage material in the heat storage tank. That is, one end 4a of the flow passage 4 is a low melting point side of the latent heat storage materials 31 to 33, and the other end 4b is a high melting point side of the latent heat storage materials 31 to 33.

  More specifically, the flow passage 4 includes first to third heat exchange units 42, 44, and 46 disposed in the heat storage tanks 21 to 23. The 1st-3rd heat exchange parts 42, 44, and 46 comprise the heat exchanger which performs heat exchange between latent heat storage materials 21-23 and water with a fin not illustrated. Moreover, the flow path 4 is interposed between the 1st heat storage tank 21 and the 2nd heat storage tank 22, and the 1st communication part 43 which connects the 1st heat exchange part 42 and the 2nd heat exchange part 44, and 2nd heat storage It has the 2nd communication part 45 which intervenes between the tank 22 and the 3rd heat storage tank 23, and connects the 2nd heat exchange part 44 and the 3rd heat exchange part 46. As shown in FIG. Further, the flow passage 4 is located on the opposite side of the first communication portion 43 with the first heat storage tank 21 interposed therebetween, and the flow passage 4 guides water from one end 4a of the communication passage 4 to the first heat exchanger portion 42 or vice versa. The first input / output unit 41 and the third heat storage tank 23 are located on the opposite side of the second communication unit 45, and the third heat exchange unit 46 guides water to the other end 4b of the communication path 4 or vice versa. 2 input / output unit 47.

  The latent heat storage materials 31 to 33 housed in the first to third heat storage tanks 21 to 23 have a melting point of the high-temperature latent heat storage material 33 equal to or higher than the design hot water supply temperature (for example, 40 ° C.) and all the latent heat storage materials. The subcooling release temperature of 31 to 33 is not particularly limited as long as it is equal to or higher than the temperature of water supplied through the supply path 71 (for example, 9 ° C.). However, the latent heat storage materials 31 to 33 are the temperature of the water flowing out from the second heat storage tank 22 when the medium temperature latent heat storage material 32 undergoes a phase change from liquid to solid, the overcooling release temperature of the high temperature latent heat storage material 33, and the low temperature latent heat. The condition that the temperature of the water flowing out from the first heat storage tank 21 when the heat storage material 31 undergoes a phase change from liquid to solid and the subcooling release temperature of the intermediate temperature latent heat storage material 32 are satisfied in this order are satisfied. preferable.

  As such latent heat storage materials 31 to 33, for example, hydrate heat storage materials can be used. Examples of the hydrate heat storage material include a calcium chloride hydrate-containing heat storage material, a sodium acetate hydrate-containing heat storage material, and a sodium sulfate hydrate-containing heat storage material. Especially, it is preferable to use together and use a sodium acetate hydrate containing heat storage material and a sodium sulfate hydrate containing heat storage material from a viewpoint of producing | generating the hot water of the temperature suitable for hot water supply on said preferable conditions.

  In this embodiment, as an example, the high-temperature latent heat storage material 33 has a melting point and a supercooling release temperature of 56 ° C. and 25 ° C., respectively, and a heat storage material mainly composed of sodium acetate hydrate (from sodium acetate trihydrate) A medium temperature latent heat storage material 32 having a melting point and a supercooling release temperature of 32 ° C. and 15 ° C., respectively, and a heat storage material mainly composed of sodium sulfate hydrate (sodium sulfate 10 to 10). A heat storage material mainly composed of sodium sulfate hydrate having a melting point and a supercooling release temperature of 23 ° C. and 10 ° C., respectively, as the low-temperature latent heat storage material 31. (Including water that would give sodium sulfate 25-26 hydrate).

  Further, a first temperature sensor 61 for detecting the temperature of the low-temperature latent heat storage material 31 is disposed in the first heat storage tank 21, and a first temperature sensor 61 for detecting the temperature of the intermediate temperature latent heat storage material 32 is provided in the second heat storage tank 22. A second temperature sensor 62 is disposed, and a third temperature sensor 63 that detects the temperature of the high-temperature latent heat storage material 33 is disposed in the third heat storage tank 23.

  Furthermore, 1 A of heat storage systems of this embodiment are the 1st bypass path 73 branched from the supply path 71 to the 1st connection part 43, and the 2nd bypass path branched from the supply path 71 to the 2nd connection part 45. 74. The distribution path 72 is provided with a mixing valve 76, and a short circuit path 75 branched from the supply path 71 is connected to the mixing valve 76.

  In the present embodiment, the first upstream region 74 a of the second bypass channel 74 is a common channel with the upstream region 73 a of the first bypass channel 73, and the upstream region 75 a of the short circuit 75 is the second bypass channel 74. The flow path is common to the second upstream area 74b including the first upstream area 74a. In other words, in the present embodiment, the short-circuit path 75 and the first connecting portion 43 are bridged in the downstream region of the first bypass passage 73, and the short-circuit passage 75 and the second connecting portion 45 are downstream of the second bypass passage 74. It can be said that it is bridged in the area. However, the first bypass path 73, the second bypass path 74, and the short circuit path 75 may each be a single flow path.

  The supply passage 71 is provided with a main flow opening / closing valve 81 downstream of the position where the bypass passages 73 and 74 are branched. The first bypass path 73 is provided with a branch opening / closing valve 82 on the downstream side of the upstream area 73a, and the second bypass path 74 is provided with a branch opening / closing valve 83 on the downstream side of the second upstream area 74b. It has been.

  The tributary on-off valve 82 permits or prohibits the flow of water from the supply path 71 through the first bypass path 73 to the first connecting portion 43, and the tributary on-off valve 83 from the supply path 71 through the second bypass path 74. The distribution of water to the second communication unit 45 is permitted or prohibited. That is, the branch opening / closing valves 82 and 83 function as the flow restricting means of the present invention.

  The main flow opening / closing valve 81 is opened while all the branch flow opening / closing valves 82, 83 are closed, and is closed when one of the branch flow opening / closing valves 82, 83 is opened.

  The control device 9 controls the heat pump 10, the water pump 53, and the various valves described above to perform a heat storage operation and a heat dissipation operation. In particular, during the heat radiation operation, the control device 9 controls the main flow opening / closing valve 81 and the branch flow opening / closing valves 82 and 83 based on the temperatures detected by the first to third temperature sensors 61 to 63. Specifically, the tributary on-off valve 82 has a temperature of the intermediate temperature latent heat storage material 32 housed in the second heat storage tank 22 located on the distribution path 72 side of the first connecting portion 43 to which the first bypass path 73 is connected (that is, the first The branch opening / closing valve 83 is accommodated in the third heat storage tank 23 located on the distribution path 72 side of the second connecting portion 45 to which the second bypass path 74 is connected. It is controlled based on the temperature of the high-temperature latent heat storage material 33 (that is, the temperature detected by the third temperature sensor 63).

  Next, a heat storage operation and a heat radiation operation performed by the control device 9 will be described with reference to FIGS. In the following description, the precondition is that water is heated to 70 ° C. by the radiator 12 during the heat storage operation, the temperature of the water supplied through the supply path 71 during the heat dissipation operation is 9 ° C., and the desired tapping temperature is 40 ° C. Assume that it is in ° C.

(Heat storage operation)
FIG. 2 shows the flow of refrigerant and water during the heat storage operation. At the time of the heat storage operation, the control device 9 first switches the three-way valves 51 and 52 to a state where the flow passage 4 and the heat storage passage 50 communicate with each other. And the control apparatus 9 operates the heat pump 10 and the water pump 53, and heats water in the radiator 12.

  The water heated by the radiator 12 flows through the flow path 4 from the other end 4b to the one end 4a, so that the high temperature latent heat storage material 33 in the third heat storage tank 23 and the medium temperature latent heat storage material 32 in the second heat storage tank 22 are obtained. After the heat is radiated sequentially to the low-temperature latent heat storage material 31 in the first heat storage container 21, the heat flows again into the radiator 12 and is heated. By repeating this operation, the latent heat storage materials 31 to 33 are dissolved, and the latent heat storage materials 31 to 33 are stored.

  The temperature of the water that radiates heat to the latent heat storage materials 31 to 33 and flows into the radiator 12 again is the temperature near the melting point of the low temperature latent heat storage material 31 in the first heat storage tank 21 through which water finally passes (that is, 23 ° C. Therefore, the heating efficiency of the heat pump 10 is higher than that of the heat storage system in which only the high-temperature latent heat storage material having a melting point higher than the design hot water supply temperature is installed.

  In addition, when the low-temperature latent heat storage material 31 in the first heat storage tank 21 is completely dissolved, the temperature of the water flowing into the radiator 12 rises as the temperature of the low-temperature latent heat storage material 31 rises. When the temperature of the water flowing into the radiator 12 reaches 60 ° C., for example, the heat storage operation is finished.

(Heat dissipation operation)
FIG. 3 shows the flow of water in a steady state during the heat radiation operation. In addition, below, the case where the thermal radiation operation is started from the state in which all the latent heat storage materials 31 to 33 in the heat storage tanks 21 to 23 become a high-temperature liquid close to 70 ° C. will be described.

  During the heat radiation operation, the control device 9 first switches the three-way valves 51 and 52 to a state in which the flow path 4, the supply path 71, and the distribution path 72 communicate with each other. Then, as a steady state, the control device 9 closes the branch on-off valves 82 and 83 and opens the main flow on-off valve 81 so that the water from the supply path 71 flows into only the first heat storage tank 21.

  The water flowing into the first heat storage tank 21 is heated by the low-temperature latent heat storage material 31, flows out from the first heat storage tank 21, and flows into the second heat storage tank 22. The water flowing into the second heat storage tank 22 is heated by the intermediate temperature latent heat storage material 32, flows out of the second heat storage tank 22, and flows into the third heat storage tank 23. The water flowing into the third heat storage tank 23 is heated by the high-temperature latent heat storage material 33 and flows out of the third heat storage tank 23. The water flowing out from the third heat storage tank 23 is mixed with the water extracted from the supply path 71 through the short-circuit path 75 by the mixing valve 76 in the middle of flowing through the distribution path 72 and adjusted to a desired hot water temperature. It is distributed to an abbreviated hot water tap.

  As the heat radiation operation proceeds, the temperature of the latent heat storage materials 31 to 33 is lowered, and the temperature of the water flowing out from the respective heat storage tanks 21 to 23 is also lowered as shown in FIG. In addition, the a line in FIG. 6 shows the temperature of the water which flows out out of the 1st heat storage tank 21, The b line in FIG. 6 shows the temperature of the water out of the 2nd heat storage tank 22, and in FIG. The c line indicates the temperature of the water flowing out from the third heat storage tank 23.

  Since the low-temperature latent heat storage material 31 first exchanges heat with the water flowing through the flow passage 4, the temperature lowers earlier than the intermediate-temperature latent heat storage material 32 and the high-temperature latent heat storage material 33. When the temperature of the low-temperature latent heat storage material 31 becomes the melting point (23 ° C.) or lower, supercooling occurs in the low-temperature latent heat storage material 31, but the temperature of water supplied through the supply path 71 (9 ° C.) Since it is lower than the supercooling release temperature (10 ° C.), the supercooling of the low-temperature latent heat storage material 31 is released as soon as it occurs. For this reason, the temperature of the low-temperature latent heat storage material 31 is maintained in the vicinity of the melting point as it is after reaching the melting point. The temperature of the water flowing out of the first heat storage tank 21 when the low-temperature latent heat storage material 31 undergoes a phase change from liquid to solid is about 18 ° C., which is slightly lower than the melting point of the low-temperature latent heat storage material 31.

  Further, when the heat radiation operation time elapses and the temperature of the intermediate temperature latent heat storage material 32 falls below the melting point (32 ° C.), the intermediate temperature latent heat storage material 32 is overcooled. Here, the temperature of the water flowing out from the first heat storage tank 21 when the low-temperature latent heat storage material 31 undergoes a phase change from liquid to solid is higher than the supercooling release temperature (15 ° C.) of the intermediate temperature latent heat storage material 32. For this reason, if nothing is controlled, the supercooled state of the intermediate temperature latent heat storage material 32 is maintained for a long period of time, and the temperature of the water flowing out of the second heat storage tank 22 greatly decreases as shown by the line b 'in FIG. . In order to prevent this, the control device 9 shifts to the first bypass state as shown in FIG.

  Specifically, when the temperature detected by the second temperature sensor 62 becomes equal to or lower than the first intermediate temperature set temperature TM1, the control device 9 closes the main flow opening / closing valve 81 and opens the branch flow opening / closing valve 82. Thereby, the flow of water through the first bypass path 73 is started, and the water from the supply path 71 flows directly into the second heat storage tank 22. Since the temperature (9 ° C.) of the water supplied through the supply path 71 is lower than the overcooling release temperature of the intermediate temperature latent heat storage material 32, the overcooling of the intermediate temperature latent heat storage material 32 is released immediately after the transition to the first bypass state.

  Here, the first intermediate temperature set temperature TM1 is a temperature determined in advance according to the melting point of the intermediate temperature latent heat storage material 32. For example, the first intermediate temperature set temperature TM1 may be equal to the melting point of the intermediate temperature latent heat storage material 32, or may be slightly higher or lower (for example, a temperature within the range of the melting point ± 2 ° C.). Good.

  Even if the supercooling of the intermediate temperature latent heat storage material 32 is released, the detected intermediate temperature latent heat storage material 32 until the crystallization of the intermediate temperature latent heat storage material 32 propagates from the vicinity of the upstream end of the heat exchange unit 44 to the vicinity of the temperature detection unit. The temperature continues to drop. When the crystallization of the intermediate temperature latent heat storage material 32 propagates to the vicinity of the temperature detection unit, the detected temperature of the intermediate temperature latent heat storage material 32 starts to increase and rises to the melting point. That is, the supercooling release can be detected by detecting the temperature rise of the intermediate temperature latent heat storage material 32.

  Therefore, when the supercooling of the intermediate temperature latent heat storage material 32 is released, the control device 9 returns from the first bypass state to the steady state shown in FIG. Specifically, the control device 9 closes the branch opening / closing valve 82 and opens the main flow opening / closing valve 81 when the temperature detected by the second temperature sensor 62 becomes equal to or higher than the second intermediate temperature set temperature TM2. Thereby, the flow of water through the first bypass path 73 is stopped, and the water from the supply path 71 flows into only the first heat storage tank 21 again.

  Here, the second intermediate temperature set temperature TM2 is a temperature equal to or lower than the melting point of the intermediate temperature latent heat storage material 32, and is a temperature determined in advance according to the first intermediate temperature set temperature TM1. For example, the second intermediate temperature set temperature TM2 may be equal to the melting point of the intermediate temperature latent heat storage material 32, or may be equal to the first intermediate temperature set temperature TM1 when the first intermediate temperature set temperature TM1 is lower than the melting point.

  In the first bypass state, water that has not been heated by the low-temperature latent heat storage material 31 flows into the second heat storage tank 22, so that the temperature of the water flowing out of the second heat storage tank 22 temporarily drops as shown in FIG. . However, as the temperature returns to the steady state, the temperature of the water flowing out from the second heat storage tank 22 rises, so the period during which the temperature of the water flowing out from the second heat storage tank 22 falls is short. The temperature of the water flowing out of the second heat storage tank 22 when the intermediate temperature latent heat storage material 32 undergoes a phase change from liquid to solid is about 28 ° C., which is slightly lower than the melting point of the intermediate temperature latent heat storage material 32.

  When the heat radiation operation time further elapses and the temperature of the high-temperature latent heat storage material 33 becomes equal to or lower than the melting point (56 ° C.), the high-temperature latent heat storage material 33 is overcooled. Here, the temperature of the water flowing out of the second heat storage tank 22 when the medium temperature latent heat storage material 32 undergoes a phase change from liquid to solid is higher than the supercooling release temperature (25 ° C.) of the high temperature latent heat storage material 33. For this reason, if nothing is controlled, the supercooled state of the high-temperature latent heat storage material 33 is maintained for a long period of time as indicated by line c 'in FIG. In order to prevent this, the control device 9 shifts to the second bypass state as shown in FIG.

  Specifically, the control device 9 closes the main flow opening / closing valve 81 and opens the branch flow opening / closing valve 83 when the temperature detected by the third temperature sensor 63 becomes equal to or lower than the first high temperature set temperature TH1. Thereby, the circulation of water through the second bypass path 74 is started, and the water from the supply path 71 flows directly into the third heat storage tank 23. Since the temperature (9 ° C.) of the water supplied through the supply path 71 is lower than the supercooling release temperature of the high-temperature latent heat storage material 33, the supercooling of the high-temperature latent heat storage material 33 is released immediately after the transition to the second bypass state.

  Here, the first high temperature set temperature TH1 is a temperature determined in advance according to the melting point of the high temperature latent heat storage material 33. For example, the first high-temperature set temperature TH1 may be equal to the melting point of the high-temperature latent heat storage material 33, or may be slightly higher or lower (for example, a temperature within the range of melting point ± 2 ° C.). Good.

  Even if the supercooling of the high-temperature latent heat storage material 33 is released, the detected high-temperature latent heat storage material 33 until crystallization of the high-temperature latent heat storage material 33 propagates from the vicinity of the upstream end of the heat exchange unit 46 to the vicinity of the temperature detection unit. The temperature continues to drop. When the crystallization of the high-temperature latent heat storage material 33 propagates to the vicinity of the temperature detection unit, the temperature of the detected high-temperature latent heat storage material 33 starts to increase and rises to the melting point. That is, the supercooling release can be detected by detecting the temperature rise of the high-temperature latent heat storage material 33.

  Therefore, when the supercooling of the high-temperature latent heat storage material 33 is released, the control device 9 returns from the second bypass state to the steady state shown in FIG. Specifically, when the temperature detected by the third temperature sensor 63 becomes equal to or higher than the second high temperature set temperature TH2, the control device 9 closes the branch opening / closing valve 83 and opens the main flow opening / closing valve 81. Thereby, the flow of water through the second bypass passage 74 is stopped, and the water from the supply passage 71 flows into the first heat storage tank 21 again.

  Here, the second high temperature set temperature TH2 is a temperature equal to or lower than the melting point of the high temperature latent heat storage material 32, and is a temperature determined in advance according to the first high temperature set temperature TH1. For example, the second high temperature set temperature TH2 may be equal to the melting point of the high temperature latent heat storage material 33, or may be equal to the first high temperature set temperature TH1 when the first high temperature set temperature TH1 is lower than the melting point.

  In the second bypass state, water that is not heated by the low-temperature latent heat storage material 31 and the intermediate-temperature latent heat storage material 32 flows into the third heat storage tank 23, and therefore flows out of the third heat storage tank 23 as shown in FIG. The water temperature drops once. However, since the temperature of the water flowing out from the third heat storage tank 23 increases with the return to the steady state, the period during which the temperature of the water flowing out from the third heat storage tank 23 falls is short. The temperature of the water flowing out from the third heat storage tank 23 when the high temperature latent heat storage material 33 undergoes a phase change from liquid to solid is about 50 ° C., which is slightly lower than the melting point of the high temperature latent heat storage material 33.

  As described above, in the heat storage system 1A of the present embodiment, water from the supply path 71 is directly supplied to the heat storage tank 22 (or 23) that houses the latent heat storage material 32 (or 33) in which supercooling has occurred. Therefore, the supercooling can be quickly released.

(Second Embodiment)
Next, with reference to FIG. 7 and FIG. 8, the thermal storage system 1B which concerns on 2nd Embodiment of this invention is demonstrated. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, the main flow rate adjusting valve 85 is provided on the downstream side of the supply passage 71 from the position where the bypass passages 73 and 74 are branched. The first bypass path 73 is provided with a branch flow rate adjusting valve 86 on the downstream side of the upstream area 73a (see FIG. 1), and the second bypass path 74 has a second upstream area 74b (see FIG. 1). A tributary flow rate adjusting valve 87 is provided on the downstream side.

  The tributary flow rate adjustment valve 86 permits or prohibits the flow of water from the supply path 71 through the first bypass path 73 to the first connecting portion 43, and the tributary flow rate adjustment valve 87 is a supply path through the second bypass path 74. The distribution of water from 71 to the second communication unit 45 is permitted or prohibited. That is, the tributary flow rate adjusting valves 86 and 87 function as the flow restriction means of the present invention.

  The main flow rate adjusting valve 81 is fully opened while all the tributary flow rate adjusting valves 86 and 87 are fully closed, and a predetermined opening degree is opened when one of the tributary flow rate adjusting valves 86 and 87 is opened to a predetermined degree. Maintained. That is, in the present embodiment, the first bypass state and the second bypass state during the heat radiation operation are only slightly different from the first embodiment, and the transition from the steady state to the first bypass state and the second bypass state, The return from the first bypass state and the second bypass state to the steady state is performed in the same manner as in the first embodiment.

  Specifically, the control device 9 fully opens the main flow rate adjustment valve 85 and fully closes the branch flow rate adjustment valves 86 and 87 in a steady state during the heat radiation operation.

  In the first bypass state, as shown in FIG. 7, when the temperature detected by the second temperature sensor 62 becomes equal to or lower than the first intermediate temperature set temperature TM1, the control device 9 opens the branch flow rate adjustment valve 86 for a predetermined amount. The opening degree of the main flow rate adjusting valve 85 is reduced by a predetermined amount. Thereby, the flow of water through the first bypass path 73 is started, and the mixed water in which the water from the supply path 71 and the water flowing out from the first heat storage tank 21 are mixed flows into the second heat storage tank 22. The predetermined opening degree of both the flow rate adjusting valves 85 and 86 at this time is an opening degree at which the temperature of the mixed water becomes equal to or lower than the supercooling release temperature (15 ° C.) of the intermediate temperature latent heat storage material 32. The predetermined opening may be set in advance or may be adjusted while detecting the temperature of the mixed water. Thereby, the supercooling of the intermediate temperature latent heat storage material 32 is canceled immediately after the transition to the first bypass state.

  Further, when the temperature detected by the second temperature sensor 62 becomes equal to or higher than the second intermediate temperature set temperature TM2, the control device 9 fully closes the tributary flow rate adjustment valve 86 and fully opens the main flow rate adjustment valve 85. To do. Thereby, the flow of water through the first bypass path 73 is stopped, and the water from the supply path 71 flows into only the first heat storage tank 21 again.

  In the second bypass state, as shown in FIG. 8, when the temperature detected by the third temperature sensor 63 becomes equal to or lower than the first high temperature set temperature TH1, the control device 9 opens the tributary flow rate adjustment valve 87. The opening degree of the main flow rate adjusting valve 85 is reduced by a predetermined amount. Thereby, the flow of water through the second bypass path 74 is started, and the mixed water in which the water from the supply path 71 and the water flowing out from the second heat storage tank 22 are mixed flows into the third heat storage tank 23. The said predetermined opening degree of both the flow regulating valves 85 and 87 at this time is an opening degree from which the temperature of mixed water becomes below the supercooling cancellation | release temperature (25 degreeC) of the high-temperature latent heat storage material 33. The predetermined opening may be set in advance or may be adjusted while detecting the temperature of the mixed water. Thereby, the supercooling of the high-temperature latent heat storage material 33 is released immediately after the transition to the second bypass state.

  Further, when the temperature detected by the third temperature sensor 63 becomes equal to or higher than the second high temperature set temperature TH2, the control device 9 fully closes the tributary flow rate adjustment valve 87 and opens the main flow rate adjustment valve 85 fully. To do. Thereby, the flow of water through the second bypass passage 74 is stopped, and the water from the supply passage 71 flows into the first heat storage tank 21 again.

  By releasing supercooling with mixed water whose temperature has been adjusted as in the present embodiment, as shown in FIG. 9, it flows out from the second heat storage tank 22 in the first bypass state seen in the first embodiment. A drop in the temperature of water and a drop in the temperature of water flowing out of the third heat storage tank 23 in the second bypass state can be suppressed.

  In the second bypass state described above, the tributary flow rate adjustment valve 86 provided in the first bypass passage 73 was not operated. However, in the second bypass state, all the flow rate adjustment valves 85 to 87 were opened at the same time. You may adjust the temperature of the water which flows in into the 3rd thermal storage tank 23 with the opening degree of these flow regulating valves 85-87.

(Other embodiments)
In the said 1st and 2nd embodiment, although the heat radiator 12 of the heat pump 10 was used as a heating means to heat water, a heating means is not restricted to this. For example, it is also possible to use a heating means that uses exhaust heat from a fuel cell or gas engine, exhaust heat from a factory, a solar heat collector, or the like as a heat source.

  In applications other than the hot water heater, for example, an antifreeze liquid may be used as a heat medium that exchanges heat with the latent heat storage material.

  The heat storage system of the present invention can effectively release the heat stored in the latent heat storage material because it can quickly release the supercooling even if the high melting point latent heat storage material is overcooled. . Therefore, the heat storage system of the present invention is not only used as a hot water heater, but also useful for applications such as a heating system and an exhaust heat utilization system.

DESCRIPTION OF SYMBOLS 1 Heat storage system 21-23 Heat storage tank 31-33 Latent heat storage material 4 Flow path 4a One end 4b Other end 43,45 Connection part 5 Heat storage circuit 50 Heat storage path 61-63 Temperature sensor 71 Supply path 72 Distribution path 73, 74 Bypass path 81 Main flow opening / closing valve 82, 83 Branch flow opening / closing valve (flow rate regulating means)
85 Main flow rate adjusting valve 86, 87 Branch flow rate adjusting valve (flow rate regulating means)
9 Control device 10 Heat pump 12 Radiator (heating means)

Claims (12)

A heat storage system using two or more latent heat storage materials having different melting points,
A heat storage tank that individually accommodates each of the latent heat storage materials; and
A flow passage for passing a heat medium that exchanges heat with the latent heat storage material and passing through the heat storage tank in order of increasing melting point of the latent heat storage material in the heat storage tank, and interposed between the heat storage tanks A flow passage having one or more connecting portions to:
A supply path for supplying a heat medium to one end on the low melting point side of the latent heat storage material in the flow path;
A distribution path for extracting a heat medium from the other end of the latent heat storage material on the high melting point side in the flow path;
One or more bypass paths branching from the supply path to each of the connecting sections;
Distribution regulation means for permitting or prohibiting distribution of the heat medium from the supply path through the bypass path to the communication portion, provided in each of the bypass paths;
Equipped with a,
Two types of the latent heat storage materials housed in the two heat storage tanks adjacent to each other through the communication part are the excess of the latent heat storage material having a lower melting point than the latent heat storage material having a lower melting point. The condition that the temperature is higher than the cooling release temperature ,
Thermal storage system. A temperature sensor for detecting the temperature of the latent heat storage material in the heat storage tank;
A control device for controlling the flow regulating means based on the temperature detected by the temperature sensor;
The heat storage system according to claim 1, further comprising:   The controller controls each of the flow regulation means, and the temperature of the latent heat storage material accommodated in the heat storage tank located on the distribution path side of the connecting portion to which the bypass path provided with the flow regulation means is connected is determined. When the temperature becomes lower than the first set temperature, the flow of the heat medium through the bypass passage provided with the flow restriction means is started, and when the temperature becomes equal to or higher than the second set temperature, the flow restriction means is provided. The heat storage system according to claim 2, wherein the heat storage system is controlled to stop circulation of the heat medium through the bypass path.   The heat storage according to any one of claims 1 to 3, wherein the flow regulating means is an on-off valve, and an on-off valve is provided on a downstream side of a position where the bypass passage branches in the supply passage. system.   The open / close valve provided in the supply path is opened while the open / close valve provided in the bypass path is closed, and is closed when the open / close valve provided in the bypass path is opened. The heat storage system described in 1.   The said distribution control means is a flow regulating valve, The flow regulating valve is provided also in the downstream rather than the position where the said bypass path branches in the said supply path. Heat storage system.   The flow rate adjusting valve provided in the supply path is fully opened while the flow rate adjusting valve provided in the bypass path is fully closed, and the flow rate adjusting valve provided in the bypass path is opened by a predetermined opening degree. The heat storage system according to claim 6, wherein the heat storage system is maintained in a state of being opened at a predetermined opening when being operated.   The heat storage system according to any one of claims 1 to 7, wherein a mixing valve is provided in the distribution path, and a short circuit branched from the supply path is connected to the mixing valve.   The heat storage system according to any one of claims 1 to 8, wherein the latent heat storage material is a hydrate heat storage material.   The heat storage system according to claim 9, wherein the hydrate heat storage material includes a sodium acetate hydrate-containing heat storage material and a sodium sulfate hydrate-containing heat storage material.   The heat storage system as described in any one of Claims 1-10 further provided with the thermal storage path which comprises a thermal storage circuit with the said flow path via the heating means which heats a thermal medium.   The heat storage system according to claim 11, wherein the heating means is a heat pump radiator.

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