JP6052215B2 - Heat storage device - Google Patents

Description

  The present invention relates to a heat storage device.

  Conventionally, a hot water supply apparatus combining a heat pump cycle and a solar heat collector has been proposed. Patent Document 1 below describes a hot water storage operation in which when the amount of remaining hot water in the hot water storage tank is small and the surface temperature of the solar heat collector is high, hot water heated by the heat pump circuit flows into the high temperature solar heat collector to store hot water. An apparatus for performing is disclosed.

Japanese Patent No. 5187184 (FIG. 2)

  In the apparatus shown in Patent Document 1, when the heat pump is stopped, the low-temperature water taken out from the lower part of the hot water storage tank is heated by the solar heat collector, and solar energy can be effectively used. Can not. In addition, a large number of water circuit flow path switching valves (first three-way valve 58, second three-way valve 60, third three-way valve 86, fourth three-way valve 87, etc.) are required, the water circuit configuration is complicated, and the equipment cost is low. Increase.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a heat storage device that can effectively use solar energy with a simple water circuit configuration.

  The heat storage device according to the present invention is a heat storage tank that stores a liquid by forming a temperature stratification with a high temperature on the upper side and a low temperature on the lower side, a heat pump heating means that heats the liquid, a solar heat heating means that heats the liquid with solar heat, A lower feed path for sending the liquid taken out from the lower part of the heat storage tank to the heat pump heating means, an intermediate return path for returning the liquid from the heat pump heating means to a height position between the upper and lower parts of the heat storage tank, and an upper part of the heat storage tank A middle feed path for sending the liquid taken out from the position between the height and the lower part to the solar heating means, and an upper return path for returning the liquid from the solar heating means to the upper part of the heat storage tank.

  According to the present invention, solar energy can be effectively used with a simple water circuit configuration.

It is a block diagram which shows the thermal storage apparatus of Embodiment 1 of this invention. It is the graph which showed the relationship between the heating temperature of a heat pump unit, the solar energy utilization efficiency of the heat pump unit driven with photovoltaic power, and the solar energy utilization efficiency of a solar heat collector.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a heat storage device according to Embodiment 1 of the present invention. As shown in FIG. 1, the heat storage device according to the first embodiment includes a hot water storage unit 1, a heat pump unit 2, and a solar heat collector 3. The hot water storage unit 1 includes a heat storage tank 6 (hot water storage tank). The heat storage tank 6 stores a liquid (water in the first embodiment) by forming a temperature stratification with a high temperature on the upper side and a low temperature on the lower side. The heat storage tank 6 has a shape that is long in the vertical direction so as to allow temperature stratification due to a difference in water density. In the present invention, liquids other than water (for example, antifreeze liquid, brine, etc.) may be stored in the heat storage tank 6.

  A water supply pipe 4 is connected to the lower part of the heat storage tank 6. Low-temperature water supplied from a water source such as water supply flows into the lower part of the heat storage tank 6 through the water supply pipe 4. A hot water supply pipe 5 is connected to the upper part of the heat storage tank 6. When a hot water supply request is generated, high-temperature water at the top of the heat storage tank 6 is supplied to the load side through the hot water supply pipe 5. At this time, the low temperature water from the water supply pipe 4 flows into the lower part of the heat storage tank 6 so that the heat storage tank 6 is maintained in a full water state. In the present invention, the liquid stored in the heat storage tank 6 may be sent to the heating equipment or the like through the hot water supply pipe 5, and the liquid passing through the heating equipment or the like may return to the heat storage tank 6 through the water supply pipe 4. good.

  The heat pump unit 2 is a heat pump heating means for heating the liquid (water). The heat pump unit 2 has a refrigeration cycle circuit in which a compressor 13, a hot water heat exchanger 14, an expansion valve 15, and an evaporator 16 are sequentially connected by a refrigerant pipe. The evaporator 16 is provided with a blower 17 for adjusting the amount of heat exchange between the outside air and the refrigerant. The refrigeration cycle circuit of the heat pump unit 2 collects heat from the outside air by the evaporator 16 and performs an operation of heating water by the hot water heat exchanger 14.

  The lower part of the heat storage tank 6 and the water inlet of the hot water heat exchanger 14 are connected via a lower feed path 26. The position of the height between the upper part and the lower part of the heat storage tank 6 and the water outlet of the hot water heat exchanger 14 are connected via a middle return path 27. A water pump 7 is disposed in the middle return path 27.

  The solar heat collector 3 is solar heat heating means for heating a liquid (water) with solar heat. The position of the height between the upper part and the lower part of the heat storage tank 6 and the water inlet of the solar heat collector 3 are connected via the middle feed path 28. A water pump 8 is disposed in the middle of the middle feed path 28. The upper part of the heat storage tank 6 and the water outlet of the solar heat collector 3 are connected via an upper return path 29. In the first embodiment, the upper return path 29 is connected to the top 20 of the heat storage tank 6.

  A temperature sensor 9 and a temperature sensor 10 are attached to the heat storage tank 6. The temperature sensor 9 is attached at a position lower than the connection position 12 between the middle feed path 28 and the heat storage tank 6. The temperature sensor 10 is attached at a position higher than the connection position 12.

  The heat pump unit 2 can be operated with electric power generated by the solar power generation panel 22 (solar power generation means). The photovoltaic power generation panel 22 is connected to the power conditioner 23. The power conditioner 23 is connected to the system power line 24. The power conditioner 23 is connected to the heat pump unit 2 via the heat pump unit power line 25. In the power conditioner 23, it is possible to select whether the power generated by the photovoltaic power generation panel 22 is sold to the grid power via the grid power line 24 or supplied to the heat pump unit 2 via the heat pump unit power line 25. It has become. The heat pump unit 2 can also be operated with electric power supplied from the system power line 24.

  The heat storage device according to the first embodiment includes a control unit 50. The control unit 50 is configured by, for example, a microcomputer, and includes a storage unit including a ROM, a RAM, a nonvolatile memory, and the like, an arithmetic processing device (CPU) that executes arithmetic processing based on a program stored in the storage unit, And an input / output port for inputting / outputting external signals to / from the arithmetic processing unit. The control unit 50 is connected to various actuators and sensors of the heat storage device. The operation of the heat storage device is controlled by the control unit 50.

  Next, the operation | movement operation | movement of the thermal storage apparatus of this Embodiment 1 is demonstrated. When a hot water supply request is generated and high temperature water in the heat storage tank 6 is supplied to the hot water supply pipe 5, low temperature water (for example, 10 ° C.) from the water supply pipe 4 flows into the lower part of the heat storage tank 6. The temperature sensor 9 is a temperature sensor that detects the minimum required hot water storage amount. When the temperature detected by the temperature sensor 9 is equal to or lower than a predetermined temperature (for example, 40 ° C.), the control unit 50 determines that the amount of stored hot water is insufficient, and performs a heat storage operation using the heat pump unit 2 (hereinafter referred to as “heat storage operation”). (Referred to as “heat pump heat storage operation”).

  In the heat pump heat storage operation, the compressor 13 is operated, the refrigerant that has received heat from the outside air and evaporated by the evaporator 16 is compressed by the compressor 13, and the high-temperature and high-pressure refrigerant is sent to the hot water heat exchanger 14. Moreover, the low temperature water taken out from the connection position 21 between the heat storage tank 6 and the lower feed path 26 is sent to the hot water heat exchanger 14 by operating the water pump 7. In the hot water heat exchanger 14, the high-temperature and high-pressure refrigerant and water exchange heat, and the water is heated. The water heated by the hot water heat exchanger 14 flows into the heat storage tank 6 from the connection position 11 between the heat storage tank 6 and the middle return path 27. By such a heat pump heat storage operation, the water layer heated by the hot water heat exchanger 14 of the heat pump unit 2 expands downward from the connection position 11 in the heat storage tank 6.

  A temperature sensor 18 is provided on the water outlet side of the solar heat collector 3. The control unit 50 determines whether there is solar radiation based on the temperature detected by the temperature sensor 18. When the temperature detected by the temperature sensor 18 is equal to or higher than a predetermined temperature (for example, 70 ° C.), the control unit 50 determines that there is solar radiation and starts the solar heat collecting operation. In the solar heat collecting operation, the water pump 8 is operated, so that the water taken out from the connection position 12 between the heat storage tank 6 and the middle feed path 28 is sent to the solar heat collector 3. The water heated by the solar heat collector 3 flows into the heat storage tank 6 from the top 20. By such solar heat collection operation, in the heat storage tank 6, the layer of water heated by the solar heat collector 3 expands downward from the top 20 and is stored in a range above the connection position 12. The The solar heat collector 3 can use the amount of heat of about 60% of the amount of solar radiation for warm water heating without being substantially affected by the outside air temperature and the incoming water temperature. It is preferable to perform solar heat collection operation whenever there is solar radiation.

  The temperature sensor 10 detects the upper hot water storage temperature representing the region heated by the solar heat collector 3. On a clear day, the temperature of the upper hot water storage is raised to, for example, about 70 ° C., and the amount of heat stored in the heat storage tank 6 increases. Thus, when the heat storage amount by the solar heat collection operation is large, the heat storage amount by the heat pump heat storage operation may be relatively small. For this reason, when the heat storage amount by the solar heat collection operation is large, the control unit 50 sets the temperature detected by the temperature sensor 9 when the heat pump heat storage operation is terminated to a relatively low temperature (for example, about 45 ° C.).

  When the amount of heat collected by the solar heat collector 3 is low, such as when a cloudy day continues, the amount of heat stored by the solar heat collection operation becomes small. When the heat storage amount by the solar heat collection operation is small, the heat storage amount by the heat pump heat storage operation is made relatively large in order to make the total heat storage amount of the heat storage tank 6 more than necessary. In this case, the control unit 50 sets the temperature detected by the temperature sensor 9 when the heat pump heat storage operation is terminated to a relatively high temperature (for example, about 55 ° C.).

  By supplying the hot water in the heat storage tank 6 to the hot water supply pipe 5, the layer of water heated by the heat pump unit 2 stored in the heat storage tank 6 moves upward. Thereby, the layer of water heated by the heat pump unit 2 stored in the heat storage tank 6 contacts the connection position 12. Therefore, in the solar heat collecting operation, water heated by the heat pump unit 2 stored in the heat storage tank 6 is taken out from the connection position 12 to the middle feed path 28 and heated by the solar heat collector 3.

  The solar heat collector 3 can use the heat energy collected from the sun as it is for warm water heating, regardless of the incoming water temperature. For this reason, rather than heating low temperature water with the solar heat collector 3 and producing | generating intermediate temperature water, the direction which heats medium temperature water with the solar heat collector 3 and produces | generates high temperature water has a large exergy obtained. That is, the exergy obtained is higher when the temperature of water entering the solar heat collector 3 is higher. In this Embodiment 1, since the water (medium temperature water) heated with the heat pump unit 2 stored in the heat storage tank 6 can be heated with the solar-heat collector 3, and high temperature water can be produced | generated, the obtained Excel Gee increases and solar energy can be used more effectively. In addition, when producing | generating high temperature water with the solar-heat collector 3, in order to reduce the heat dissipation loss from the solar-heat collector 3, it is desirable to make the solar-heat collector 3 into a structure with high heat insulation.

  The heat storage tank 6 can be reduced in size by setting the hot water stored in the heat storage tank 6 as high as possible. In this Embodiment 1, since the water (for example, 50 degreeC) heated with the heat pump unit 2 can be heated with the solar-heat collector 3, high temperature water (for example, 70 degreeC) can be produced | generated, Thermal storage of the thermal storage tank 6 The density can be increased and the heat storage tank 6 can be downsized. On the other hand, when heating from low temperature water to high temperature water by solar heat, the amount of high temperature water obtained is small, and the heat storage density of the heat storage tank 6 cannot be increased.

  In the first embodiment, even when the heat pump unit 2 is stopped, the water heated by the heat pump unit 2 stored in the heat storage tank 6 can be supplied to the solar heat collector 3. For this reason, even when the heat pump unit 2 is stopped during the solar heat collecting operation, the temperature of water entering the solar heat collector 3 can be increased. Moreover, in this Embodiment 1, it can suppress that a water circuit becomes a complicated structure with a flow-path switching valve etc., and can use solar energy effectively with a simple water circuit structure.

  The lower the temperature of the water coming out of the heat pump unit 2, that is, the heating temperature of the heat pump unit 2, the higher the efficiency of the heat pump unit 2. In Embodiment 1, since the water heated by the heat pump unit 2 is further heated by the solar heat collector 3, the heating temperature of the heat pump unit 2 may be relatively low. For this reason, the efficiency of the heat pump unit 2 can be increased.

  When the high temperature water in the heat storage tank 6 is supplied to the hot water supply pipe 5 and the low temperature water from the water supply pipe 4 flows into the lower part of the heat storage tank 6, the lower low temperature water layer in the heat storage tank 6 expands upward. To go. When the lower low temperature water layer in the heat storage tank 6 reaches the connection position 12 between the middle feed path 28 and the heat storage tank 6, the incoming water temperature to the solar heat collector 3 decreases. On the other hand, in the first embodiment, heat storage is started by starting the heat pump heat storage operation based on the temperature detected by the temperature sensor 9 located at a position lower than the connection position 12 between the middle feed path 28 and the heat storage tank 6. The heat pump heat storage operation can be performed before the lower low temperature water layer in the tank 6 reaches the connection position 12. For this reason, it can suppress reliably that the incoming water temperature to the solar-heat collector 3 falls.

  Immediately after the heat pump unit 2 is activated, the temperature of the water coming out of the heat pump unit 2 is low, so that low temperature water may flow into the heat storage tank 6 from the connection position 11. In addition, the water pump 7 may be operated without starting the heat pump unit 2 in a freeze prevention operation or the like, and low temperature water may flow into the heat storage tank 6 from the connection position 11. Since the low-temperature water has a high density, the low-temperature water flowing into the heat storage tank 6 from the connection position 11 diffuses downward. Therefore, even if low temperature water flows into the heat storage tank 6 from the connection position 11, the temperature of the hot water above the connection position 11 does not decrease. In this Embodiment 1, even if low temperature water flows in into the thermal storage tank 6 from the connection position 11 because the connection position 11 is in a position lower than the connection position 12, the temperature of the hot water of the connection position 12 does not fall. Therefore, even if the low temperature water flows into the heat storage tank 6 from the connection position 11, it is possible to reliably suppress a decrease in the incoming water temperature to the solar heat collector 3.

  Then, the electric power supply method to the heat pump unit 2 in this Embodiment 1 is demonstrated. The power supply system of the heat pump unit 2 can select and use two systems of power generated by the solar power generation panel 22 and power supplied from the system power line 24.

  When the heat pump heat storage operation is requested, the power conditioner 23 selects the power generated by the solar power generation panel 22 (hereinafter referred to as “solar power generation power”) with priority. At this time, the solar heat collector 3 is also operated, and the heat pump heat storage operation and the solar heat collection operation are simultaneously performed. In this case, as shown in FIG. 2, the operation efficiency of the entire system changes depending on how much each of the heat pump heat storage operation and the solar heat collection operation is heated.

  FIG. 2 is a graph showing the relationship between the heating temperature of the heat pump unit 2, the solar energy utilization efficiency of the heat pump unit 2 driven by photovoltaic power generation, and the solar energy utilization efficiency of the solar heat collector 3. As described above, in the solar heat collecting operation, water heated by the heat pump unit 2 stored in the heat storage tank 6 flows into the solar heat collector 3. For this reason, the incoming water temperature to the solar heat collector 3 is substantially equal to the heating temperature of the heat pump unit 2. The solar energy utilization efficiency of the solar heat collector 3 is almost constant (about 60%), being less affected by the heating temperature of the heat pump unit 2 (≈water temperature entering the solar heat collector 3) and the outside air temperature. On the other hand, the solar energy utilization efficiency of the heat pump unit 2 driven by solar power generation varies greatly depending on the heating temperature of the heat pump unit 2. That is, the lower the heating temperature of the heat pump unit 2, the higher the solar energy utilization efficiency of the heat pump unit 2 driven by solar power. Moreover, the higher the evaporation temperature of the evaporator 16, the higher the solar energy utilization efficiency of the heat pump unit 2 driven by the photovoltaic power. The higher the outside air temperature, the higher the evaporation temperature of the evaporator 16.

  When the heating temperature of the heat pump unit 2 is low, the solar energy utilization efficiency of the heat pump unit 2 driven by photovoltaic power is higher than the solar energy utilization efficiency of the solar heat collector 3. As the heating temperature of the heat pump unit 2 increases, the difference between the solar energy utilization efficiency of the heat pump unit 2 driven by photovoltaic power generation and the solar energy utilization efficiency of the solar heat collector 3 is reduced, and the magnitude relationship is further increased. Reverse. That is, when the heating temperature of the heat pump unit 2 is high, the solar energy utilization efficiency of the heat pump unit 2 driven by photovoltaic power is lower than the solar energy utilization efficiency of the solar heat collector 3.

  As described above, the higher the incoming temperature to the solar heat collector 3 (≈the heating temperature of the heat pump unit 2), the more advantageous is the exergy obtained by the solar heat collection operation. However, as shown in FIG. 2, the higher the heating temperature of the heat pump unit 2, the lower the solar energy utilization efficiency of the heat pump unit 2 driven by photovoltaic power generation. Therefore, in the first embodiment, the heat pump unit 2 is heated so that the solar energy utilization efficiency of the heat pump unit 2 driven by the photovoltaic power and the solar energy utilization efficiency of the solar heat collector 3 are substantially equal. Temperature is preferred, and the heating temperature of the heat pump unit 2 at the intersection of the graph of FIG. 2 is optimal. By controlling the heating temperature of the heat pump unit 2 to such a preferable target value, the use of solar energy of the heat pump unit 2 driven by photovoltaic power generation while sufficiently increasing the exergy obtained by the solar heat collecting operation Efficiency can be increased sufficiently.

  As described above, the optimum heating temperature of the heat pump unit 2 when the heat pump unit 2 is driven by photovoltaic power is the intersection of the graphs in FIG. Therefore, as the evaporation temperature of the evaporator 16 is higher, the optimum heating temperature of the heat pump unit 2 when the heat pump unit 2 is driven by photovoltaic power is higher. Therefore, when performing the heat pump heat storage operation driven by photovoltaic power generation, it is preferable that the control unit 50 controls the heating temperature of the heat pump unit 2 according to the evaporation temperature of the evaporator 16. That is, it is preferable that the controller 50 controls the heating temperature of the heat pump unit 2 to be higher as the evaporation temperature of the evaporator 16 is higher. In addition, the control part 50 can control the heating temperature of the heat pump unit 2 to a target value by adjusting the water flow rate by the water pump 7. The heating temperature of the heat pump unit 2 can be detected by a temperature sensor 19 provided on the outlet side of the hot water heat exchanger 14. Further, the evaporation temperature of the evaporator 16 may be detected by providing a temperature sensor at or near the evaporator 16, or the evaporation temperature may be estimated based on the outside air temperature or the like. By controlling as described above, the heating temperature of the heat pump unit 2 when the heat pump unit 2 is driven by photovoltaic power can be more reliably brought close to the optimum value.

DESCRIPTION OF SYMBOLS 1 Hot water storage unit, 2 Heat pump unit, 3 Solar thermal collector, 4 Water supply piping, 5 Hot water supply piping, 6 Heat storage tank, 7, 8 Water pump, 9, 10 Temperature sensor, 11, 12 Connection position, 13 Compressor, 14 Hot water Heat exchanger, 15 Expansion valve, 16 Evaporator, 17 Blower, 18, 19 Temperature sensor, 20 Top, 21 Connection position, 22 Solar power generation panel, 23 Power conditioner, 24 System power line, 25 Heat pump unit power line, 26 Lower part Feed path, 27 Middle return path, 28 Middle feed path, 29 Upper return path, 50 Control section

Claims (4)

A heat storage tank for storing liquid by forming a temperature stratification in which the upper side is high temperature and the lower side is low temperature;
A heat pump heating means for heating the liquid;
Solar heating means for heating the liquid with solar heat;
A lower feed path for sending the liquid taken out from the lower part of the heat storage tank to the heat pump heating means;
A middle return path for returning liquid from the heat pump heating means to a height position between the upper and lower portions of the heat storage tank;
A middle feed path for sending the liquid taken from the position between the upper and lower parts of the heat storage tank to the solar heating means;
An upper return path for returning liquid from the solar heating means to the upper part of the heat storage tank;
A heat storage device comprising:   The heat storage device according to claim 1, wherein a connection position between the middle return path and the heat storage tank is lower than a connection position between the middle feed path and the heat storage tank. A temperature sensor attached to the heat storage tank at a position lower than the connection position between the middle feed path and the heat storage tank;
The heat storage device according to claim 1 or 2, wherein a heat storage operation by the heat pump heating unit is started based on a temperature detected by the temperature sensor.   The heat storage device according to any one of claims 1 to 3, wherein the temperature of the liquid coming out of the heat pump heating unit is changed according to an evaporation temperature of an evaporator of the heat pump heating unit.

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