JP5252282B2 - Heat storage device - Google Patents

Description

  The present invention relates to a heat storage device that stores waste heat generated in a heat source facility such as a power plant or a waste incineration plant.

  Waste heat generated in heat source facilities (for example, power plants, waste incinerators, steelworks, chemical plants) is effectively discarded in heat utilization facilities (for example, office buildings, hospitals, hotels, and Kurhaus). There is known a heat storage device that stores heat in a heat storage tank, transports the heat storage tank to a heat utilization facility, and performs hot water supply, air conditioning, and the like using the heat storage tank as a heat source (Patent Document 1).

  The heat storage device includes a heat storage tank that stores a latent heat storage material and a heat medium oil having a specific gravity smaller than that of the latent heat storage material in two upper and lower layers, and a discharge pipe that discharges the heat medium oil into the heat storage tank. And a recovery pipe that opens the suction port in the heat transfer oil layer in the heat storage tank, and the heat transfer oil is circulated between the heat source facility (or heat utilization facility) and the heat storage tank through the discharge pipe and the recovery pipe. Let it be used. At this time, the heat transfer oil discharged from the discharge pipe into the heat storage tank is in direct contact with the latent heat storage material and exchanges heat while rising in the latent heat storage material layer due to a specific gravity difference from the latent heat storage material.

Here, the latent heat storage material is a heat storage material that stores and releases heat using heat (latent heat) that is absorbed and discharged when the phase changes between the solid phase and the liquid phase. Heat is absorbed from the surroundings when changing, and heat is discharged when changing from a liquid phase to a solid phase. In addition, since the temperature of the latent heat storage material does not change when the phase changes between the solid phase and the liquid phase, it is possible to radiate heat at a constant temperature. As such a latent heat storage material, for example, sodium acetate trihydrate, erythritol, and mannitol are used.
JP 2007-147093 A

  By the way, since the heat storage device directly contacts the heat transfer oil with the latent heat storage material in the heat storage tank, when the heat transfer oil is circulated between the heat source facility or the heat utilization facility and the heat storage tank, The latent heat storage material of the phase flows out of the heat storage tank together with the heat transfer oil, and the latent heat storage material is cooled in the pipe outside the heat storage tank to become a solid phase, and the latent heat storage material adheres to the inner surface of the pipe and There is a risk of blockage.

  In particular, if the flow rate of the heat transfer oil is increased in order to increase the speed of heat storage and release, the latent heat storage material in the heat storage tank is agitated by the heat transfer oil, so that the latent heat storage material tends to flow out of the heat storage tank. There is a possibility that the piping outside the heat storage tank may be blocked by the leaked latent heat storage material. Once the piping is closed, the heat transfer oil cannot flow into the piping, so it is difficult to return the latent heat storage material in the piping to the liquid phase, and it is not easy to remove the latent heat storage material in the piping.

  The problem to be solved by the present invention is to prevent the piping outside the heat storage tank from being blocked by the latent heat storage material flowing out from the heat storage tank.

  In order to solve the above-mentioned problems, the inventor of the present invention, when increasing the flow rate of the heat medium oil and mixing the latent heat storage material into the heat medium oil layer, the latent heat storage material is located above the suction port of the recovery pipe. It was found that a supernatant composed of a heat transfer oil not mixed with water was formed, and the supernatant was used to prevent clogging of piping outside the heat storage tank.

  Specifically, a second recovery pipe is provided that branches from the recovery pipe outside the heat storage tank and opens a suction port in the heat transfer medium oil layer in the heat storage tank, and the suction port of the second recovery pipe serves as the recovery pipe. And a valve that is arranged above the suction port and switches between which of the recovery pipe and the second recovery pipe is used to recover the heat transfer oil.

  By doing this, even when the latent heat storage material flows out into the pipe outside the heat storage tank during the heat storage and heat dissipation operation, the valve is switched so that the heat transfer oil passes through the second recovery pipe after the heat storage and heat dissipation operation is completed. The heat transfer oil that does not contain the latent heat storage material can flow into the piping outside the heat storage tank. As a result, the heat medium oil mixed with the latent heat storage material in the pipe outside the heat storage tank is replaced with the heat medium oil not mixed with the latent heat storage material, so the pipe outside the heat storage tank is not blocked.

  In addition, the above-described problem is that a storage tank that stores heat transfer oil is provided separately from the heat storage tank, and a second recovery pipe that branches from the recovery pipe outside the heat storage tank and opens a suction port in the storage tank is provided. The problem can also be solved by providing a valve for switching between the recovery pipe and the second recovery pipe through which the heat transfer oil is recovered.

  By doing this, even when the latent heat storage material flows out into the pipe outside the heat storage tank during the heat storage and heat dissipation operation, the valve is switched so that the heat transfer oil passes through the second recovery pipe after the heat storage and heat dissipation operation is completed. The heat transfer oil that does not contain the latent heat storage material can flow into the piping outside the heat storage tank. As a result, the heat medium oil mixed with the latent heat storage material in the pipe outside the heat storage tank is replaced with the heat medium oil not mixed with the latent heat storage material, so the pipe outside the heat storage tank is not blocked.

  In these heat storage devices, during the heat storage and heat dissipation operation, the valve is switched so that the heat transfer oil passes through the recovery pipe, and after the heat storage and heat release operation, the valve is set so that the heat transfer oil passes through the second recovery pipe. A control unit for switching can be provided.

  When the control unit is provided, the heat storage tank is provided with a latent heat storage material detection sensor for detecting whether or not a latent heat storage material is mixed in the heat transfer medium oil layer, and the control unit is the latent heat storage material detection sensor. It is preferable that the valve is switched after the end of the heat storage and heat radiation operation only when mixing of the latent heat storage material is detected. This is efficient because the switching of the valve after the end of the heat storage and heat radiation operation is performed only when the latent heat storage material flows out into the piping outside the heat storage tank.

  Further, when the control unit is provided, the recovery pipe is provided with a latent heat storage material detection sensor that detects whether or not a latent heat storage material is mixed in the heat transfer medium oil flowing in the recovery pipe, and the control unit has its latent heat Only when the mixing of the latent heat storage material is detected by the heat storage material detection sensor, switching of the valve after the end of the heat storage and heat radiation operation may be performed. Even if it does in this way, switching of the valve | bulb after completion | finish of a thermal storage heat | fever operation is efficient because it is performed only when a latent heat storage material flows out into piping outside a thermal storage tank.

  As the latent heat storage material detection sensor, for example, a capacitance for detecting the latent heat storage material based on a change in capacitance when the latent heat storage material comes into contact with a capacitance detection probe inserted in the heat transfer oil A sensor can be employed.

  Since the heat storage device of this invention can clean the inside of piping outside a heat storage tank with the heat transfer oil in which the latent heat storage material is not mixed after completion | finish of a thermal storage heat radiation operation, piping outside a heat storage tank does not obstruct | occlude. Therefore, it is possible to increase the flow rate of the heat transfer oil to increase the speed of heat storage and release.

  In FIG. 1, waste heat generated in a heat source facility 1 (for example, a power plant, a waste incineration plant, a steel mill, a chemical plant) is converted into a heat utilization facility 2 (for example, an office building, a hospital, a hotel, This shows a heat transfer system that can be used in Kurhaus.

  This heat transfer system is detachably connected to the waste heat pipe 3 through which a waste heat medium (for example, hot water or steam) generated in the heat source facility 1 flows, and the heat storage device 4 according to the embodiment of the present invention. A heat exchanger 6 that performs heat exchange between the heat medium pipe 5 and the waste heat pipe 3 and the heat medium pipe 5 is provided, and the circulation pump 7 is operated with the heat storage device 4 connected to the heat medium pipe 5. Thus, the heat medium oil in the heat medium pipe 5 can be circulated between the heat storage device 4 and the heat exchanger 6. At this time, heat is transferred from the waste heat medium flowing through the waste heat pipe 3 to the heat medium oil flowing through the heat medium pipe 5, and the heat of the heat medium oil is stored in the heat storage device 4.

  Moreover, this heat transfer system includes a heat utilization pipe 8 through which a heat utilization medium (for example, heating water or hot water supply water) flows, and a heat medium pipe 9 detachably connected to the heat storage device 4 on the heat utilization facility 2 side. A heat exchanger 10 that performs heat exchange between the heat utilization pipe 8 and the heat medium pipe 9 is provided, and heat is generated by operating the circulation pump 11 with the heat storage device 4 connected to the heat medium pipe 9. The heat transfer oil in the medium tube 9 can be circulated between the heat storage device 4 and the heat exchanger 10. At this time, heat is transmitted from the heat medium oil flowing through the heat medium pipe 9 to the hot water supply water and heating water flowing through the heat utilization pipe 8, and hot water supply and air conditioning are performed by the heat.

  As described above, this heat transfer system uses waste heat of the heat source facility 1 as heat energy of the heat utilization facility 2 by moving the heat storage device 4 back and forth between the heat source facility 1 and the heat utilization facility 2. It is.

  As shown in FIG. 2, the heat storage device 4 includes a cylindrical heat storage tank 12 whose central axis is horizontal. In the heat storage tank 12, a latent heat storage material 13 and a heat transfer oil 14 having a specific gravity smaller than that of the latent heat storage material 13 are accommodated. The latent heat storage material 13 and the heat medium oil 14 are separated into two upper and lower layers by the difference in specific gravity to form a heat medium oil layer 15 and a latent heat storage material layer 16.

  The latent heat storage material 13 absorbs heat from the surroundings when the phase changes from the solid phase to the liquid phase, and discharges heat when the phase changes from the liquid phase to the solid phase. As such latent heat storage material 13, for example, sodium acetate trihydrate, erythritol, mannitol, magnesium chloride hexahydrate and the like can be used.

  In addition, the heat storage device 4 includes a discharge pipe 17 that discharges the heat medium oil 14 into the heat storage tank 12, a recovery pipe 18 and a second recovery pipe 19 that recover the heat medium oil 14 from the heat storage tank 12, and latent heat storage material detection. Sensor 20.

  The discharge pipe 17 is provided horizontally in the latent heat storage material layer 16 in the heat storage tank 12. The discharge pipe 17 is formed with a number of downward discharge ports 21 through which the heat transfer oil 14 supplied from the outside of the heat storage tank 12 is discharged into the latent heat storage material layer 16.

  The recovery pipe 18 is provided horizontally in the heat medium oil layer 15 in the heat storage tank 12, and a number of upward suction ports 22 that open into the heat medium oil layer 15 are formed. The heat transfer oil 14 sucked from the suction port 22 passes through the recovery pipe 18 and is recovered outside the heat storage tank 12.

  The latent heat storage material detection sensor 20 is attached to the wall surface of the heat storage tank 12, and the capacitance detection probe 23 is inserted into the heat transfer oil layer 15. Here, the latent heat storage material detection sensor 20 detects the latent heat storage material 13 based on a change in capacitance when the latent heat storage material 13 comes into contact with the capacitance detection probe 23 inserted in the heat transfer oil 14. This is a capacitance sensor that detects whether or not the latent heat storage material 13 is mixed in the heat medium oil 14 in the vicinity of the suction port 22 of the recovery pipe 18 in the heat medium oil layer 15.

  The second recovery pipe 19 branches from the recovery pipe 18 outside the heat storage tank 12 and opens the suction port 24 in the heat transfer medium oil layer 15 in the heat storage tank 12. The suction port 24 of the second recovery pipe 19 is disposed above the suction port 22 of the recovery pipe 18.

  The recovery pipe 18 is provided with an electric valve 25 closer to the heat storage tank 12 than a branch portion of the second recovery pipe 19, and an electric valve 26 is also provided in the middle of the second recovery pipe 19. By operating 25 and 26, it is possible to switch between the recovery pipe 18 and the second recovery pipe 19 to collect the heat transfer oil 14.

  That is, when the electric valve 25 of the recovery pipe 18 is opened and the electric valve 26 of the second recovery pipe 19 is closed, the heat transfer oil 14 is recovered through the recovery pipe 18 and the electric valve 25 of the recovery pipe 18 is closed. At the same time, when the electric valve 26 of the second recovery pipe 19 is opened, the heat transfer oil 14 is recovered through the second recovery pipe 19.

  The heat storage device 4 is provided with a control unit (not shown) that controls these electric valves 25 and 26. The control unit switches the electric valves 25 and 26 so that the heat transfer oil 14 passes through the recovery pipe 18 during the heat storage and heat dissipation operation, and after the heat storage and heat release operation, the heat transfer oil 14 passes through the second recovery pipe 19. The electric valves 25 and 26 are switched to each other. In addition, the control unit is configured to receive a detection signal of the latent heat storage material detection sensor 20, and only when the latent heat storage material detection sensor 20 detects the mixing of the latent heat storage material 13 during the heat storage and release operation. The electric valves 25 and 26 are switched after the end of the heat storage and heat dissipation operation.

  The heat storage device 4 is provided with a porous plate 27 that partitions the heat storage tank 12 so as to cover the discharge pipe 17. A large number of through holes are formed in the porous plate 27 over the entire surface.

  When the heat storage device 4 performs a heat radiation operation, as shown in the lower side of FIG. 1, the heat medium pipe 9 of the heat utilization facility 2 is connected to the discharge pipe 17 and the recovery pipe 18, and the circulation pump 11 is operated in that state. The heat transfer oil 14 is circulated between the heat storage device 4 and the heat exchanger 10.

  At this time, as shown in FIG. 3, the low-temperature heat transfer oil 14 fed into the discharge pipe 17 from the heat medium pipe 9 is discharged into the heat storage tank 12 through the discharge pipe 17 and below the perforated plate 27. The heat transfer oil 14 accumulated on the side passes through the porous plate 27 and is sent out to the upper side of the porous plate 27 by the pressure of the heat transfer oil 14 discharged from the discharge pipe 17. Further, the liquid phase latent heat storage material 13 accumulated under the porous plate 27 is also sent out to the upper side of the porous plate 27 through the porous plate 27 by the pressure of the heat transfer oil 14 discharged from the discharge pipe 17. The heat transfer oil 14 sent to the upper side of the porous plate 27 through the porous plate 27 rises in the heat storage tank 12 due to the difference in specific gravity with the latent heat storage material 13, and flows out to the heat transfer medium tube 9 through the recovery pipe 18. To do.

  Here, the heat transfer oil 14 directly contacts the latent heat storage material 13 and exchanges heat in the process of rising in the heat storage tank 12. By this heat exchange, crystals of the latent heat storage material 13 are generated, and the crystals aggregate to form an aggregate. Aggregates having a certain size descend in the heat storage tank 12 and are received by the perforated plate 27 and accumulated. Therefore, when the heat radiation operation is finished, the discharge pipe 17 is in the heat transfer oil 14.

  On the other hand, when the heat storage device 4 performs a heat storage operation, as shown in the upper side of FIG. 1, the heat medium pipe 5 of the heat source facility 1 is connected to the discharge pipe 17 and the recovery pipe 18, and the circulation pump 7 is operated in this state. The heat transfer oil 14 is circulated between the heat storage device 4 and the heat exchanger 6.

  At this time, as shown in FIG. 4, the high-temperature heat medium oil 14 fed into the discharge pipe 17 from the heat medium pipe 5 is discharged into the heat medium oil 14 collected around the discharge pipe 17, and the heat After being mixed with the medium oil 14 and losing momentum, it passes through the porous plate 27 and is sent to the upper side of the porous plate 27. The heat transfer oil 14 sent to the upper side of the porous plate 27 through the porous plate 27 rises in the heat storage tank 12 due to the specific gravity difference with the latent heat storage material 13. In this ascending process, the latent heat storage material 13 in the heat storage tank 12 directly contacts the heat transfer oil 14 to receive heat, and changes from a solid phase to a liquid phase.

  As described above, the heat storage device 4 directly stores the heat medium oil 14 in contact with the latent heat storage material 13 in the heat storage tank 12 to store and release heat. Therefore, the flow rate of the heat medium oil 14 is increased in order to increase the speed of heat storage and release. Is increased, the heat transfer oil 14 stirs the latent heat storage material 13 in the heat storage tank 12, and a mixed layer 28 of the latent heat storage material 13 and the heat transfer oil 14 is temporarily formed in the heat storage tank 12. Therefore, the latent heat storage material 13 easily flows out to the heat medium pipes 5 and 9 outside the heat storage tank 12, and there is a possibility that the heat medium pipes 5 and 9 and the heat exchangers 6 and 10 are blocked by the discharged latent heat storage material 13. Arise.

  Further, since the upward flow in the heat storage tank 12 disappears in the vicinity of the suction port of the recovery pipe 18, the latent heat storage material 13 is not mixed in the heat storage tank 12 above the suction port 22 of the recovery pipe 18. A supernatant 29 made of the heat transfer oil 14 is formed.

  Next, a cleaning operation for preventing the heat medium pipes 5 and 9 and the heat exchangers 6 and 10 from being blocked using the supernatant 29 will be described.

  When the latent heat storage material detection sensor 20 detects the mixing of the latent heat storage material 13 during the heat storage operation, it is electrically driven so that the heat transfer oil 14 passes through the second recovery pipe 19 as shown in FIG. The valves 25 and 26 are switched, and thereafter, the circulation pump 7 is driven until a time preset in the timer of the control unit elapses. Thereby, the heat medium oil 14 of the supernatant 29 flows through the heat medium pipe 5 and the heat exchanger 6, and the heat medium oil 14 in the heat medium pipe 5 and the heat exchanger 6 is not mixed with the latent heat storage material 13. The heat transfer oil 14 is replaced. At this time, when the flow rate of the heat medium oil 14 is set to 0.5 m / second or more and the amount of the heat medium oil 14 that flows to the heat medium pipe 5 and the heat exchanger 6 is flowed once, heat exchange with the heat medium pipe 5 is performed. It is possible to effectively remove the latent heat storage material 13 in the vessel 6. The time for driving the circulation pump 7 is set according to the length of the heat medium pipe 5.

  If the latent heat storage material detection sensor 20 does not detect mixing of the latent heat storage material 13 during the heat storage operation, this cleaning operation is not performed.

  The above-described cleaning operation can be performed in the same manner after the heat radiation operation is completed.

  Since the heat storage device 4 cleans the heat medium pipes 5 and 9 and the heat exchangers 6 and 10 with the heat medium oil 14 in which the latent heat storage material 13 is not mixed after the heat storage and heat radiation operation ends, 9 and the heat exchangers 6 and 10 are not blocked. Therefore, it is possible to increase the flow rate of the heat medium oil 14 and increase the speed of heat storage and release.

  Further, the heat storage device 4 is efficient because the switching of the electric valves 25 and 26 after the heat storage and heat radiation operation is completed is performed only when the latent heat storage material 13 flows out of the heat storage tank 12.

  In the above embodiment, the two electric valves 25 and 26 are used as valves for switching between the recovery pipe 18 and the second recovery pipe 19 to collect the heat transfer oil 14. Instead, a three-way valve may be provided at the branch portion of the second recovery pipe 19.

  Moreover, in the said embodiment, the electrostatic capacitance detection probe 23 inserted in the heat carrier oil 14 as the latent heat storage material detection sensor 20 which detects whether the latent heat storage material 13 is mixed in the heat transfer oil layer 15 or not. Although the electrostatic capacity sensor which detects the latent heat storage material 13 based on the change of the electrostatic capacity when the latent heat storage material 13 comes into contact with is used, another type of sensor may be used. As such a sensor, for example, a cylindrical float having the same specific gravity as that of the heat transfer oil 14 is slidably fitted on the outer periphery of the rod, and the latent heat storage material 13 is mixed in the heat transfer oil 14 around the float. There is a float type sensor that detects the latent heat storage material 13 based on the ups and downs of the float.

  Moreover, in the said embodiment, the latent heat storage material detection sensor 20 is provided in the heat storage tank 12, and the latent heat storage material detection sensor 20 detects whether the latent heat storage material 13 is mixed in the heat-medium oil layer 15. FIG. However, instead of this, a latent heat storage material detection sensor 20 is provided in the recovery pipe 18, and the latent heat storage material 13 is mixed into the heat transfer oil 14 flowing in the recovery pipe 18 by the latent heat storage material detection sensor 20. You may make it detect whether it exists.

  A storage tank (not shown) for storing the heat transfer oil 14 is provided separately from the heat storage tank 12, and the suction port 24 of the second recovery pipe 19 is opened in the storage tank, and the heat stored in the storage tank. Even if the heat medium pipes 5 and 9 and the heat exchangers 6 and 10 are cleaned with the medium oil 14, the heat medium pipes 5 and 9 and the heat exchangers 6 and 10 are used with the latent heat storage material 13 flowing out from the heat storage tank 12. Can be blocked.

  Moreover, in the said embodiment, in order to relieve the stirring effect | action in the thermal storage tank 12 by the heat transfer oil 14, the perforated plate 27 which partitions off the thermal storage tank 12 so that the discharge pipe 17 may be covered is provided, but this invention Can also be applied to the heat storage device 4 in which the porous plate 27 does not exist in the heat storage tank 12.

  In the above embodiment, the heat storage device 4 has been described by taking as an example the heat transfer system that makes it possible to use the waste heat of the heat source facility 1 in the heat utilization facility 2. However, the heat storage device 4 of the present invention uses solar heat and geothermal heat. It can also be used in a heat transfer system that makes it possible to use natural energy such as in the heat utilization facility 2.

The figure which shows the heat transfer system using the heat storage apparatus of embodiment of this invention Sectional view of the heat storage device shown in FIG. Sectional drawing which shows the state at the time of the thermal radiation operation of the thermal storage apparatus shown in FIG. Sectional drawing which shows the state at the time of the thermal storage driving | operation of the thermal storage apparatus shown in FIG. Sectional drawing which shows the state at the time of the cleaning driving | operation after completion | finish of the thermal storage driving | operation of the thermal storage apparatus shown in FIG.

Explanation of symbols

4 heat storage device 12 heat storage tank 13 latent heat storage material 14 heat medium oil 15 heat medium oil layer 17 discharge pipe 18 recovery pipe 19 second recovery pipe 20 latent heat storage material detection sensor 22 suction port 23 capacitance detection probe 24 suction ports 25 and 26 Electric valve

Claims (5)

The upper and lower layers of the latent heat storage material (13) with the latent heat storage material (13) having a small specific gravity thermal oil than a heat medium oil layer on top (14) and (15) and latent heat storage material layer under (16) a heat storage tank for containing the separation state (12), a discharge pipe for discharging the heat transfer oil (14) to the latent heat storage material layer of said thermal storage tank (12) in (16) and (17), the heat storage tank ( has the heat medium oil layer (15) recovery pipe which opens an inlet (22) during a 12) and (18), by the difference in specific gravity thermal oil (14) discharged from the discharge pipe (17) In the heat storage device that exchanges heat by directly contacting the latent heat storage material (13) in the heat storage tank (12) while being raised ,
A second recovery pipe (19) that branches from the recovery pipe (18) outside the heat storage tank (12) and opens the suction port (24) in the heat transfer oil layer (15) in the heat storage tank (12). The suction port (24) of the second recovery pipe (19) is disposed above the suction port (22) of the recovery pipe (18), and the recovery pipe (18) and the second recovery pipe (19 ) To provide a valve (25, 26) for switching the heat medium oil (14) to be collected ,
The heat transfer oil (14) passes through the recovery pipe (18) during the heat storage / radiation operation, and the heat transfer oil (14) passes through the second recovery pipe (19) after the heat storage / radiation operation ends. ) By switching the heat transfer oil (14) in the pipe outside the heat storage tank (12) to the heat transfer oil (14) in which the latent heat storage material (13) is not mixed. A heat storage device.   During the heat storage and heat dissipation operation, the valves (25 and 26) are switched so that the heat transfer oil (14) passes through the recovery pipe (18), and after the heat storage and heat dissipation operation is completed, the second recovery pipe (19) is connected to the heat transfer medium (14). The heat storage device according to claim 1, further comprising a control unit that switches the valves (25, 26) so that oil (14) passes therethrough.   The heat storage tank (12) is provided with a latent heat storage material detection sensor (20) for detecting whether or not the latent heat storage material (13) is mixed in the heat transfer oil layer (15), and the control unit is configured to detect the latent heat. The heat storage device according to claim 2, wherein the valve (25, 26) is switched after the heat storage and heat dissipation operation only when the heat storage material detection sensor (20) detects the mixing of the latent heat storage material (13).   The recovery pipe (18) is provided with a latent heat storage material detection sensor (20) for detecting whether or not the latent heat storage material (13) is mixed in the heat transfer oil (14) flowing in the recovery pipe (18), The said control part performs switching of the said valve | bulb (25,26) after completion | finish of a thermal storage heat dissipation, only when mixing of the latent heat storage material (13) is detected by the latent heat storage material detection sensor (20). The heat storage device described in 1.   The latent heat storage material detection sensor (20) is based on a change in capacitance when the latent heat storage material (13) contacts the capacitance detection probe (23) inserted in the heat transfer oil (14). The heat storage device according to claim 3 or 4, wherein the heat storage device is a capacitance sensor that detects the latent heat storage material (13).

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