Control device, geothermal heat utilization system, control method, and program

Abstract

This control device comprises: an operation control unit capable of switching the operation mode of a geothermal utilization system between a heating mode in which water pumped up from a hot water well is returned to a cold water well and a cooling mode in which water pumped up from a cold water well is returned to a hot water well; a calculation unit that calculates the integrated heat storage amount of a past heating operation period during which the operation was performed in the heating mode, and the integrated heat storage amount of a past cooling operation period during which the operation was performed in the cooling mode; and an operation state adjustment unit that adjusts the operation state of the geothermal heat utilization system such that the difference between the integrated heat storage amount of a subsequent heating operation period and the integrated heat storage amount of a subsequent cooling operation period is smaller than the difference between the integrated heat storage amount of the past heating operation period and the integrated heat storage amount of the past cooling operation period.

Description

Control device, geothermal heat utilization system, control method, and program

[0001] This application claims priority to Japanese Patent Application No. 2024-090252, filed on June 3, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, geothermal energy utilization systems that utilize heat stored in wells have been proposed.

[0003] As a related technology, for example, Patent Document 1 discloses a configuration in which a heat source well facility equipped with a hot water well and a cold water well is controlled so that the annual pumped water volume and the return water volume of each of the hot water well and the cold water well are equal, and a heat storage auxiliary facility including at least one of a heating device and a cooling device is controlled so that the annual pumped water heat quantity and the return water heat quantity of both the hot water well and the cold water well are equal.

[0004] Japanese Patent Application Publication No. 2023-149312

[0005] However, depending on the region where the geothermal energy utilization system is installed, the utilization status of the heat storage in the geothermal energy utilization system, etc., even if the configuration disclosed in Patent Document 1 is adopted, it may be difficult to balance the heat quantity between the heating operation period and the cooling operation period.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a control device, a geothermal energy utilization system, a control method, and a program that can achieve a good heat balance between heating operation periods and cooling operation periods.

[0007] In order to solve the above problems, the control device according to the present disclosure is a control device for a geothermal utilization system equipped with a heat source well facility including a hot water well, a cold water well, and a heat exchanger provided in a pipe connecting the hot water well and the cold water well, and the control device has a heating mode in which heating operation is performed by using water pumped from the hot water well to perform heat exchange in the heat exchanger, and the water that has passed through the heat exchanger is returned to the cold water well, and a cooling mode in which cooling operation is performed by using water pumped from the cold water well to perform heat exchange in the heat exchanger, and the water that has passed through the heat exchanger is returned to the hot water well; a calculation unit that calculates the accumulated heat storage amount during a past heating operation period when the system was operated in the heating mode and the accumulated heat storage amount during a past cooling operation period when the system was operated in the cooling mode; and an operation state adjustment unit that adjusts the operation state of the geothermal utilization system so that the difference between the accumulated heat storage amount during a next heating operation period and the accumulated heat storage amount during a next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0008] The geothermal energy utilization system according to the present disclosure includes the control device described above and the heat source well facility.

[0009] The control method according to the present disclosure operates a geothermal utilization system by switching the operating mode of the system between a heating mode in which heating operation is performed by heat exchange using water pumped from a hot water well and the heat-exchanged water is returned to the cold water well, and a cooling mode in which cooling operation is performed by heat exchange using water pumped from the cold water well and the heat-exchanged water is returned to the hot water well, calculates the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode, and adjusts the operating state of the geothermal utilization system so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0010] The program of the present disclosure causes a computer to operate a geothermal utilization system by switching the operating mode of the geothermal utilization system between a heating mode in which heating operation is performed by heat exchanging water pumped from a hot water well and the heat-exchanged water is returned to the cold water well, and a cooling mode in which cooling operation is performed by heat exchanging water pumped from the cold water well and the heat-exchanged water is returned to the hot water well, calculate the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode, and adjust the operating state of the geothermal utilization system so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0011] According to the control device, geothermal heat utilization system, control method, and program of the present disclosure, a good heat balance can be achieved between the heating operation period and the cooling operation period.

[0012] 1 is a system diagram of a geothermal energy utilization system according to an embodiment of the present disclosure; 2 is a block diagram of a control device according to an embodiment of the present disclosure; 3 is a flowchart of a control method according to an embodiment of the present disclosure;

[0013] Embodiments Hereinafter, a control device, a geothermal energy utilization system, a control method, and a program according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 4. FIG.

[0014] (Configuration of Geothermal Energy Utilization System) As shown in Fig. 1, the geothermal energy utilization system 1 includes a heat source well facility 10, an auxiliary heat source 30, a heat exchanger 40, and a control device 50. When the heat load LD (e.g., air conditioning load) is operating in heating mode, the geothermal energy utilization system 1 uses the heat of the hot water stored in the heat source well facility 10 for heating and simultaneously stores the waste cold heat. When the heat load LD is operating in cooling mode, the geothermal energy utilization system 1 uses the cold of the cold water stored in the heat source well facility 10 for cooling and simultaneously stores the waste hot heat.

[0015] (Configuration of Heat Source Well Facility) The heat source well facility 10 includes a hot water well 11 , a cold water well 12 , and piping 13 .

[0016] The hot water well 11 and the cold water well 12 each extend from the ground into the aquifer LY. The hot water well 11 and the cold water well 12 each include a casing with a screen, and are configured to take in groundwater from the aquifer LY and return groundwater from the inside of the hot water well 11 and the cold water well 12 to the aquifer LY. During steady-state operation of the geothermal energy utilization system 1, hot water is stored in the aquifer LY around the hot water well 11, and cold water is stored in the aquifer LY around the cold water well 12. The hot water well 11 and the cold water well 12 are located at a distance from each other that is sufficient to prevent the stored hot water and cold water from mixing.

[0017] In the geothermal energy utilization system 1, the heat source well facility 10 pumps groundwater from one of the hot water well 11 and the cold water well 12 to the surface, performs heat exchange on the surface for heat utilization, and injects the water into the other of the hot water well 11 and the cold water well 12. In other words, the heat source well facility 10 has two operating modes: one in which groundwater is pumped from the hot water well 11 and injected into the cold water well 12, and one in which groundwater is pumped from the cold water well 12 and injected into the hot water well 11.

[0018] Piping 13 connects hot water well 11 and cold water well 12. One end of piping 13, that is, a first end 131, extends into the hot water well 11 and is immersed in the groundwater inside hot water well 11. The other end of piping 13, that is, a second end 132, extends into the cold water well 12 and is immersed in the groundwater inside cold water well 12.

[0019] Each of the first end 131 and the second end 132 is provided with a pump PP, an adjusting valve RV, a check valve CV, etc., and is configured to adjust the flow rate of water in the pipe 13. The pump PP can change its output by inverter control in response to a command from the control device 50. The adjusting valve RV can change its opening in response to a command from the control device 50.

[0020] (Configuration of Auxiliary Heat Source) The auxiliary heat source 30 is, for example, a heat pump. This heat pump includes a condenser, an evaporator, a compressor, etc., and cools or heats the heat load LD.

[0021] (Configuration of Heat Exchanger) The heat exchanger 40 exchanges heat between the water in the pipe 13 and the medium on the heat load LD side. Specifically, the heat exchanger 40 exchanges heat between groundwater pumped from the hot water well 11 and flowing through the pipe 13, which serves as the water in the pipe 13, and the medium on the heat load LD side. The groundwater after heat exchange flows from the heat exchanger 40 through the pipe 13 and is injected into the cold water well 12. Conversely, the heat exchanger 40 exchanges heat between the groundwater pumped from the cold water well 12 and flowing through the pipe 13, which serves as the water in the pipe 13, and the medium on the heat load LD side. The groundwater after heat exchange flows from the heat exchanger 40 through the pipe 13 and is injected into the hot water well 11. The heat exchanger 40 is provided midway through the pipe 13, which extends above ground.

[0022] If the water that has passed through the heat exchanger 40 is hot water, hot water heat storage is performed in the hot water well 11. If the water that has passed through the heat exchanger 40 is cold water, cold water heat storage is performed in the cold water well 12. Here, "hot water" refers to water with a temperature higher than the initial underground temperature of the groundwater in the aquifer LY, and "cold water" refers to water with a temperature lower than the initial underground temperature of the groundwater in the aquifer LY. For example, the initial underground temperature of the groundwater in the aquifer LY is 18°C.

[0023] (Configuration of Control Device) As shown in FIG. 2, the control device 50 includes, as its hardware configuration, a CPU 51, a memory 52, a communication interface 53, and a recording medium 54.

[0024] The CPU 51 is a processor that performs various functions by operating in accordance with a pre-prepared program. The functions of the CPU 51 will be described later.

[0025] The memory 52 has a storage area necessary for the operation of the CPU 51 .

[0026] The communication interface 53 is a connection interface for connecting to other devices via a communication line so that it can communicate with them, and is configured to be able to send commands to other devices and receive responses from other devices.

[0027] The recording medium 54 is a local recording medium provided within the housing of the control device 50, and is a large-capacity storage device such as an HDD or SSD.

[0028] The control device 50 functionally includes an operation control unit 501, a recording unit 502, a calculation unit 503, and an operation state adjustment unit 504. The operation control unit 501, the recording unit 502, the operation control unit 501, the calculation unit 503, and the operation state adjustment unit 504 are functionally realized by the CPU 51 operating in accordance with a program prepared in advance.

[0029] (Configuration of the operation control unit) The operation control unit 501 controls the operation of the entire geothermal energy utilization system 1. The operation control unit 501 can switch the operation mode of the geothermal energy utilization system 1 between a heating mode and a cooling mode. In the heating mode, the operation control unit 501 performs heating operation with a heat load LD by performing heat exchange in the heat exchanger 40 using groundwater (hot water) pumped from the hot water well 11. The groundwater (cold water) whose temperature has been lowered by heat exchange in the heat exchanger 40 is returned to the cold water well 12. In the cooling mode, the operation control unit 501 performs cooling operation with a heat load LD by performing heat exchange in the heat exchanger 40 using groundwater (cold water) pumped from the cold water well 12. The groundwater (hot water) whose temperature has been increased by heat exchange in the heat exchanger 40 is returned to the hot water well 11. Furthermore, the operation control unit 501 may perform heating and cooling using the auxiliary heat source 30 in addition to heat exchange in the heat exchanger 40 in at least one of the heating mode and the cooling mode.

[0030] The operation control unit 501 controls the return temperature of the groundwater returned to the hot water well 11 and the cold water well 12 after heat exchange in the heat exchanger 40 in each of the heating mode and the cooling mode so that it becomes a preset return temperature. The operation control unit 501 controls the pump PP in each of the heating mode and the cooling mode so that the flow rate of the groundwater flowing through the pipe 13 becomes a preset average flow rate. The operation control unit 501 also controls the pump PP so that the amount of water pumped from the hot water well 11 and the amount of water returned from the cold water well 12 during the heating operation period in the heating mode are equal to the amount of water pumped from the cold water well 12 and the amount of water returned from the hot water well 11 during the cooling operation period in the cooling mode.

[0031] (Configuration of Recording Unit) The recording unit 502 records the operating time, the pumped water volume, return water volume, average flow rate, average injected water temperature, average pumped water temperature, etc. of each of the hot water well 11 and the cold water well 12 during each heating operation period in heating mode and each cooling operation period in cooling mode. The recording unit 502 writes each piece of recorded data to the recording medium 54. The recording unit 502 also calculates the accumulated heat storage amount in the hot water well 11 and the cold water well 12 based on the operating time, the pumped water volume, return water volume, average flow rate, initial underground temperature, average injected water temperature, average pumped water temperature, etc. of each of the hot water well 11 and the cold water well 12, and records the calculation results in the recording unit 502. The recording unit 502 may record the most recent heating operation period or cooling operation period (i.e., for the most recent year), or the most recent multiple heating operation periods or cooling operation periods (i.e., for the most recent multiple years).

[0032] (Configuration of Calculation Unit) The calculation unit 503 calculates the accumulated heat storage amount during a past heating operation period in which operation was performed in heating mode, and the accumulated heat storage amount during a past cooling operation period in which operation was performed in cooling mode. Here, accumulated heat storage amount = (return water temperature - pumped water temperature) × pumped water volume × specific heat of water / 860. The calculation unit 503 may calculate the accumulated heat storage amount during one past heating operation period in which operation was performed in heating mode, and the accumulated heat storage amount during one past cooling operation period in which operation was performed in cooling mode. The calculation unit 503 may calculate the accumulated heat storage amount during multiple past heating operation periods in which operation was performed in heating mode, and the accumulated heat storage amount during multiple past cooling operation periods in which operation was performed in cooling mode.

[0033] (Configuration of the Operational State Adjustment Unit) The operational state adjustment unit 504 sets the operational state of the geothermal utilization system 1 for the next heating operation period and the next cooling operation period based on the actual values ​​of the past heating operation period and the next cooling operation period. The operational state adjustment unit 504 adjusts the operational state of the geothermal utilization system 1 so that the difference between the accumulated heat storage amount for the next heating operation period and the accumulated heat storage amount for the next cooling operation period is smaller than the difference between the accumulated heat storage amount for the past heating operation period and the accumulated heat storage amount for the past cooling operation period. In other words, the operational state adjustment unit 504 attempts to equalize the accumulated heat storage amount for the next heating operation period and the accumulated heat storage amount for the next cooling operation period.

[0034] If the accumulated heat storage amount in the past cooling operation period is greater than the accumulated heat storage amount in the past heating operation period, the operation state adjustment unit 504 may heat water in the next heating operation period using the auxiliary heat source 30. If the accumulated heat storage amount in the past heating operation period is greater than the accumulated heat storage amount in the past cooling operation period, the operation state adjustment unit 504 may cool water in the next cooling operation period using the auxiliary heat source 30.

[0035] Furthermore, when the accumulated heat storage amount in a past cooling operation period is greater than the accumulated heat storage amount in a past heating operation period, the operation state adjustment unit 504 may adjust the operation state of the geothermal energy utilization system 1 so that the accumulated heat storage amount in the next cooling operation period is smaller. Specifically, the operation state adjustment unit 504 may reduce the accumulated heat storage amount in the next cooling operation period by reducing the operation time in the cooling mode in the next cooling operation period. Furthermore, the operation state adjustment unit 504 may reduce the accumulated heat storage amount in the next cooling operation period by reducing the pumped water volume from the cold water well 12 and the returned water volume from the hot water well 11.

[0036] When the accumulated heat storage amount in the past heating operation period is greater than the accumulated heat storage amount in the past cooling operation period, the operation state adjustment unit 504 may adjust the operation state of the geothermal energy utilization system 1 so that the accumulated heat storage amount in the next heating operation period is smaller. Specifically, the operation state adjustment unit 504 may reduce the operation time in the heating mode in the next heating operation period so that the accumulated heat storage amount in the next heating operation period is smaller. Furthermore, the operation state adjustment unit 504 may reduce the pumped water volume in the hot water well 11 and the returned water volume in the cold water well 12 so that the accumulated heat storage amount in the next heating operation period is smaller.

[0037] The operation state adjustment unit 504 may set the return water temperature to the cold water well 12 during the next heating operation period and the return water temperature to the hot water well 11 during the next cooling operation period based on the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0038] (Operation of the Control Device) The operation of the control device 50 of this embodiment will be described. The operation of the control device 50 corresponds to an embodiment of a control method. First, prior to each step shown in FIGS. 3 and 4 , the control device 50 performs a special first cycle in the operation start year. In the special first cycle, the control device 50 first records the actual values ​​of each component to obtain the accumulated heat storage amount during the heating operation period in heating mode and the accumulated heat storage amount during the cooling operation period in cooling mode of the geothermal energy utilization system 1. At this time, the recording unit 502 records the operating time, the pumped water volume, return water volume, average flow rate, average injected water temperature, average pumped water temperature, etc. of each of the hot water well 11 and the cold water well 12 during each of the heating operation period in heating mode and the cooling operation period in cooling mode, and writes the recorded data to the recording medium 54. The recording unit 502 calculates the cumulative heat storage amount in the hot water well 11 and the cold water well 12 based on the operating time, the pumped water volume, return water volume, average flow rate, initial underground temperature, average injected water temperature, average pumped water temperature, etc. of each of the hot water well 11 and the cold water well 12, and records the calculation results in the recording unit 502. In the special first cycle, the control device 50 preferably controls the pumped water volume of the hot water well 11 and the return water volume of the cold water well 12 during the heating operation period so that they are equal to the pumped water volume of the cold water well 12 and the return water volume of the hot water well 11 during the cooling operation period.

[0039] After the first special cycle is performed, the control device 50 starts the following steps shown in Figures 3 and 4 as processing for the intermediate period after the end of the heating period or the intermediate period after the end of the cooling period. First, based on records of actual values ​​for at least one heating operation period and one cooling operation period, the calculation unit 503 calculates the accumulated heat storage amount for a past heating operation period when operation was performed in heating mode and the accumulated heat storage amount for a past cooling operation period when operation was performed in cooling mode (S11).

[0040] Next, the operation state adjustment unit 504 compares the accumulated heat amount during the past heating operation period with the accumulated heat amount during the past cooling operation period. In this embodiment, the operation state adjustment unit 504 checks whether the accumulated heat amount during the past cooling operation period is greater than the accumulated heat amount during the past heating operation period (S12).

[0041] As a result, if the accumulated heat storage amount during the past cooling operation period is greater than the accumulated heat storage amount during the past heating operation period (S12: Yes), the operation state adjustment unit 504 sets the operation state of the geothermal energy utilization system 1 for the next heating operation period based on the past heating operation period in which the accumulated heat storage amount is smaller than that during the past cooling operation period. Specifically, the operation state adjustment unit 504 sets the pumped water volume and the returned water volume of each of the hot water well 11 and the cold water well 12 to be the same as those during the past heating operation period (S13).

[0042] Next, the operation state adjustment unit 504 sets the return water temperature to the cold water well 12 for the next heating operation period (S14). To do this, a correction coefficient K is calculated, for example, using the following equation (1): K=(T0-Tp) / (T0 / Trs) (1) where T0 is the initial underground temperature (fixed value), Tp is the actual value (constant value) of the past pumped water temperature, and Trs is the average value of the past return water temperatures.

[0043] Next, the average pumped water temperature Tps is calculated using the following formula (2): Tps = T0 - (T0 - Trs) x K (2) Furthermore, the amount of heat stored Q in the return water side well (cold water well 12 in heating mode, hot water well 11 in cooling mode) is calculated using the following formula (3): Q = (Tps - Trs) x Vr x γ / 860 (3) Here, Vr is the pumped water volume, and γ is the specific heat of water.

[0044] Then, the set value Trt of the return water temperature to the return water side well for the next heating operation period is calculated using the following formula (4): Trt = Tps - Q × 860 / γ / Vr (4) The operation state adjustment unit 504 sets the return water temperature to the cold water well 12 for the next heating operation period, i.e., the set return water temperature, based on the above formula (4).

[0045] Next, the operation state adjustment unit 504 determines whether or not to use the auxiliary heat source 30 (S15). Here, whether or not to use the auxiliary heat source 30 may be determined in advance by, for example, the provider or user of the geothermal energy utilization system 1.

[0046] If the auxiliary heat source 30 is to be used (S15: Yes), the operating condition adjustment unit 504 then sets the pumped water volume, return water volume, and return water temperature so that the accumulated heat storage amount during the next cooling operation period is equal to the accumulated heat storage amount during the previous heating operation period, and sets the operating conditions of the geothermal energy utilization system 1 so that the shortfall in the accumulated heat storage amount during the previous cooling operation period is made up by cooling the water with the auxiliary heat source 30 (S16), and the setting is completed.

[0047] Furthermore, if the auxiliary heat source 30 is not used (S15: No), the operation state adjustment unit 504 reduces the operating time of the geothermal energy utilization system 1 during the cooling operation period so that the accumulated heat storage amount during the next cooling operation period is equal to the accumulated heat storage amount during the previous heating operation period (S17). Next, the operation state adjustment unit 504 sets the return water temperature to the hot water well 11 during the next cooling operation period based on the above formulas (1) to (4) in accordance with the reduced operating time (S18), and ends the setting.

[0048] Furthermore, if the accumulated heat storage amount during the previous cooling operation period is not greater than the accumulated heat storage amount during the previous heating operation period (S12: No), as shown in FIG. 4 , the operation state adjustment unit 504 sets the operation state of the geothermal energy utilization system 1 for the next cooling operation period based on the previous cooling operation period in which the accumulated heat storage amount was smaller than that during the previous heating operation period (S19). Specifically, the operation state adjustment unit 504 sets the pumped water volume and the return water volume of the hot water well 11 and the cold water well 12 to be the same as those during the previous cooling operation period. Next, the operation state adjustment unit 504 sets the return water temperature to the hot water well 11, which is the return water well, for the next cooling operation period based on the above formulas (1) to (4) (S20).

[0049] Next, the operation state adjustment unit 504 determines whether or not to use the auxiliary heat source 30 (S21).

[0050] If the auxiliary heat source 30 is used (S21: Yes), the operating condition adjustment unit 504 sets the pumped water volume, return water volume, and return water temperature so that the accumulated heat storage amount during the next heating operation period is equal to the accumulated heat storage amount during the previous cooling operation period, and then sets the operating conditions of the geothermal energy utilization system 1 so that the shortfall in the accumulated heat storage amount during the previous heating operation period is made up by heating water with the auxiliary heat source 30 (S22), and the setting is completed.

[0051] Furthermore, if the auxiliary heat source 30 is not used (S21: No), the operation state adjustment unit 504 reduces the operation time of the geothermal energy utilization system 1 during the heating operation period so that the accumulated heat storage amount during the next heating operation period is equal to the accumulated heat storage amount during the previous cooling operation period (S23). Next, the operation state adjustment unit 504 sets the return water temperature to the hot water well 11, which is the return water side well, during the next heating operation period based on the above formulas (1) to (4) (S24), and ends the setting.

[0052] (Operation and Effect) According to this embodiment, the control device 50 calculates the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period, and adjusts the operating state of the geothermal energy utilization system 1 so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period. This makes it possible to achieve a good heat balance between the heating operation period and the cooling operation period.

[0053] Furthermore, according to this embodiment, if the accumulated heat storage amount during a past cooling operation period is greater than the accumulated heat storage amount during a past heating operation period, the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period can be reduced by heating water using the auxiliary heat source 30 during the next heating operation period.

[0054] Furthermore, according to this embodiment, if the accumulated heat storage amount during a past heating operation period is greater than the accumulated heat storage amount during a past cooling operation period, the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period can be reduced by cooling water using the auxiliary heat source 30 during the next cooling operation period.

[0055] Furthermore, according to this embodiment, if the accumulated heat storage amount during a past cooling operation period is greater than the accumulated heat storage amount during a past heating operation period, the operating state of the geothermal energy utilization system 1 can be adjusted so that the accumulated heat storage amount during the next cooling operation period is smaller, thereby reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0056] Furthermore, according to this embodiment, by reducing the operating time in cooling mode during the next cooling operation period, the accumulated heat storage amount during the next cooling operation period can be reduced, and the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period can be reduced.

[0057] In addition, according to this embodiment, by reducing the pumped water volume in the cold water well 12 and the return water volume in the hot water well 11, the accumulated heat storage amount in the next cooling operation period can be reduced, and the difference between the accumulated heat storage amount in the next heating operation period and the accumulated heat storage amount in the next cooling operation period can be reduced.

[0058] Furthermore, according to this embodiment, if the accumulated heat storage amount during a past heating operation period is greater than the accumulated heat storage amount during a past cooling operation period, the operating state of the geothermal energy utilization system 1 can be adjusted so that the accumulated heat storage amount during the next heating operation period is smaller, thereby reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0059] Furthermore, according to this embodiment, by reducing the operating time in heating mode in the next heating operation period, the accumulated heat storage amount in the next heating operation period can be reduced, and the difference between the accumulated heat storage amount in the next heating operation period and the accumulated heat storage amount in the next cooling operation period can be reduced.

[0060] In addition, according to this embodiment, the accumulated heat storage amount in the next heating operation period, which reduces the pumped water volume in the hot water well 11 and the returned water volume in the cold water well 12, can be reduced, and the difference between the accumulated heat storage amount in the next heating operation period and the accumulated heat storage amount in the next cooling operation period can be reduced.

[0061] Furthermore, according to this embodiment, the return water temperature to the cold water well 12 during the next heating operation period and the return water temperature to the hot water well 11 during the next cooling operation period are set based on the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period, thereby adjusting the operating state of the geothermal energy utilization system 1 so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0062] According to the control method of this embodiment, it is possible to achieve a good heat balance between the heating operation period and the cooling operation period.

[0063] <Modifications> In the present embodiment, instead of a heat pump, a cooling tower, a solar thermal panel, a boiler, an absorption chiller / heater, or the like may be used as the auxiliary heat source 30. The auxiliary heat source 30 may be a combination of two or more of a cooling tower, a solar thermal panel, a boiler, and an absorption chiller / heater. Furthermore, although a heat pump capable of both cooling and heating a refrigerant is provided as the auxiliary heat source 30 in the above embodiment, for example, in cold regions, the auxiliary heat source 30 may be one that can only heat the refrigerant. Furthermore, for example, in warm regions, the auxiliary heat source 30 may be one that can only cool the refrigerant.

[0064] Furthermore, in step S11 of the above embodiment, when the geothermal utilization system 1 starts operating or during a trial operation prior to the operation of the geothermal utilization system 1, the accumulated heat storage amount during a heating operation period in heating mode and the accumulated heat storage amount during a cooling operation period in cooling mode are recorded for a certain period. If the difference between the accumulated heat storage amount during a previous heating operation period in heating mode and the accumulated heat storage amount during a previous cooling operation period in cooling mode during this period (referred to as the accumulated heat storage difference) is large, the operating conditions of the geothermal utilization system 1 may be adjusted to reduce the accumulated heat storage difference during the next heating operation period and the next cooling operation period. In this case, the operating conditions of the geothermal utilization system 1 may be adjusted to reduce the accumulated heat storage difference over multiple subsequent heating operation periods and multiple subsequent cooling operation periods.

[0065] In each of the above-described embodiments, a program for implementing the various functions of the control device 50 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system such as a microcomputer and executed to perform various processes. Here, the various processes of the CPU 51 of the computer system are stored in the form of a program on a computer-readable recording medium, and the computer reads and executes the program to perform the various processes. Examples of computer-readable recording media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer that receives the program may execute the program.

[0066] <Other Embodiments> Although the embodiments of the present disclosure have been described above, these embodiments are provided by way of example only and are not intended to limit the scope of the present disclosure. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the present disclosure. These embodiments and their modifications are considered to be within the scope and spirit of the present disclosure, as well as within the scope of the present disclosure and its equivalents.

[0067] <Additional Notes> The control device 50, the geothermal utilization system 1, the control method, and the program described in the embodiment can be understood, for example, as follows.

[0068] (1) The control device 50 according to the first aspect is a control device 50 for a geothermal energy utilization system 1 equipped with a heat source well facility 10 including a hot water well 11, a cold water well 12, and a heat exchanger 40 provided in a pipe 13 connecting the hot water well 11 and the cold water well 12, and has two modes: a heating mode in which heating operation is performed by using water pumped from the hot water well 11 to perform heat exchange in the heat exchanger 40, and the water that has passed through the heat exchanger 40 is returned to the cold water well 12; and a cooling mode in which cooling operation is performed by using water pumped from the cold water well 12 to perform heat exchange in the heat exchanger 40, and the water that has passed through the heat exchanger 40 is returned to the hot water well 11. a calculation unit 503 that calculates the accumulated heat storage amount during a past heating operation period when the system was operated in the heating mode and the accumulated heat storage amount during a past cooling operation period when the system was operated in the cooling mode; and an operation state adjustment unit 504 that adjusts the operation state of the geothermal utilization system 1 so that the difference between the accumulated heat storage amount during a next heating operation period and the accumulated heat storage amount during a next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0069] The control device 50 calculates the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period, and adjusts the operating state of the geothermal energy utilization system 1 so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period. This makes it possible to achieve a good heat balance between the heating operation period and the cooling operation period.

[0070] (2) The control device 50 according to the second aspect is the control device 50 of (1), and when the accumulated heat storage amount during the past cooling operation period is greater than the accumulated heat storage amount during the past heating operation period, the operation state adjustment unit 504 heats the water pumped from the hot water well 11 during the next heating operation period using an auxiliary heat source 30 provided separately from the heat exchanger 40.

[0071] As a result, if the accumulated heat storage amount during the past cooling operation period is greater than the accumulated heat storage amount during the past heating operation period, the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period can be reduced by heating water using the auxiliary heat source 30 during the next heating operation period.

[0072] (3) The control device 50 according to the third aspect is the control device 50 of (1) or (2), and when the accumulated heat storage amount during the past heating operation period is greater than the accumulated heat storage amount during the past cooling operation period, the operation state adjustment unit 504 cools the water pumped from the cold water well 12 using an auxiliary heat source 30 provided separately from the heat exchanger 40 during the next cooling operation period.

[0073] As a result, if the accumulated heat storage amount during the past heating operation period is greater than the accumulated heat storage amount during the past cooling operation period, the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period can be reduced by cooling the water using the auxiliary heat source 30 during the next cooling operation period.

[0074] (4) The control device 50 according to the fourth aspect is any one of the control devices 50 of (1) to (3), and the operating state adjustment unit 504 adjusts the operating state of the geothermal energy utilization system 1 so that the accumulated heat storage amount in the next cooling operation period is smaller when the accumulated heat storage amount in the past cooling operation period is greater than the accumulated heat storage amount in the past heating operation period.

[0075] As a result, if the accumulated heat storage amount during a past cooling operation period is greater than the accumulated heat storage amount during a past heating operation period, the operating state of the geothermal energy utilization system 1 can be adjusted so that the accumulated heat storage amount during the next cooling operation period is smaller, thereby reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0076] (5) The control device 50 according to a fifth aspect is the control device 50 of (4), in which the operation state adjustment unit 504 reduces the operation time in the cooling mode in the next cooling operation period.

[0077] This reduces the operating time in cooling mode during the next cooling operation period, thereby reducing the accumulated heat storage amount during the next cooling operation period and reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0078] (6) The control device 50 according to the sixth aspect is the control device 50 of (4) or (5), in which the operating condition adjustment unit 504 reduces the pumping volume in the cold water well 12 and the return water volume in the hot water well 11.

[0079] This reduces the pumped water volume in the cold water well 12 and the return water volume in the hot water well 11, thereby reducing the accumulated heat storage amount in the next cooling operation period and reducing the difference between the accumulated heat storage amount in the next heating operation period and the accumulated heat storage amount in the next cooling operation period.

[0080] (7) The control device 50 according to the seventh aspect is any one of the control devices 50 of (1) to (6), and the operating state adjustment unit 504 adjusts the operating state of the geothermal energy utilization system 1 so that the accumulated heat storage amount in the next heating operation period is smaller when the accumulated heat storage amount in the past heating operation period is greater than the accumulated heat storage amount in the past cooling operation period.

[0081] As a result, if the accumulated heat storage amount during a past heating operation period is greater than the accumulated heat storage amount during a past cooling operation period, the operating state of the geothermal energy utilization system 1 can be adjusted so that the accumulated heat storage amount during the next heating operation period is smaller, thereby reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0082] (8) The control device 50 according to an eighth aspect is the control device 50 of (7), in which the operation state adjustment unit 504 reduces the operation time in the heating mode in the next heating operation period.

[0083] This reduces the operating time in heating mode during the next heating operation period, thereby reducing the accumulated heat storage amount during the next heating operation period and reducing the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0084] (9) The control device 50 according to the ninth aspect is the control device 50 of (7) or (8), in which the operating condition adjustment unit 504 reduces the pumping volume in the hot water well 11 and the return water volume in the cold water well 12.

[0085] This reduces the accumulated heat storage amount in the next heating operation period, which reduces the pumped water volume in the hot water well 11 and the returned water volume in the cold water well 12, and reduces the difference between the accumulated heat storage amount in the next heating operation period and the accumulated heat storage amount in the next cooling operation period.

[0086] (10) The control device 50 according to the tenth aspect is any one of the control devices 50 of (1) to (9), and the operating state adjustment unit 504 sets the return water temperature to the cold water well 12 during the next heating operation period and the return water temperature to the hot water well 11 during the next cooling operation period based on the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

[0087] By setting the return water temperature to the cold water well 12 during the next heating operation period and the return water temperature to the hot water well 11 during the next cooling operation period based on the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period, the operating state of the geothermal energy utilization system 1 is adjusted so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0088] (11) The geothermal energy utilization system 1 according to the eleventh aspect includes any one of the control devices 50 of (1) to (10) and the heat source well facility 10.

[0089] This makes it possible to provide a geothermal energy utilization system 1 equipped with a control device 50 that can achieve a good heat balance between heating operation periods and cooling operation periods.

[0090] (12) The control method according to the twelfth aspect switches the operating mode of the geothermal energy utilization system 1 between a heating mode in which heating operation is performed by heat exchange using water pumped from a hot water well 11 and the heat-exchanged water is returned to a cold water well 12, and a cooling mode in which cooling operation is performed by heat exchange using water pumped from the cold water well 12 and the heat-exchanged water is returned to the hot water well 11, calculates the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode, and adjusts the operating state of the geothermal energy utilization system 1 so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0091] This allows a good balance of heat quantities between the heating operation period and the cooling operation period.

[0092] (13) The program relating to the thirteenth aspect causes a computer to switch the operating mode of the geothermal energy utilization system 1 between a heating mode in which heating operation is performed by heat exchange using water pumped from a hot water well 11 and the heat-exchanged water is returned to a cold water well 12, and a cooling mode in which cooling operation is performed by heat exchange using water pumped from the cold water well 12 and the heat-exchanged water is returned to the hot water well 11, calculates the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode, and adjusts the operating state of the geothermal energy utilization system 1 so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

[0093] This makes it possible to provide a computer that can achieve a good heat balance between the heating operation period and the cooling operation period.

[0094] According to the control device, geothermal heat utilization system, control method, and program of the present disclosure, a good heat balance can be achieved between the heating operation period and the cooling operation period.

[0095] 1...Geothermal heat utilization system 10...Heat source well equipment 11...Hot water well 12...Cold water well 13...Pipe 30...Auxiliary heat source 40...Heat exchanger 50...Control device 51...CPU 52...Memory 53...Communication interface 54...Recording medium 131...First end 132...Second end 501...Operation control unit 502...Recording unit 503...Calculation unit 504...Operation state adjustment unit CV...Check valve LD...Heat load LY...Aquifer PP...Pump RV...Regulating valve

Claims

1. A control device for a geothermal energy utilization system equipped with a heat source well facility including a hot water well, a cold water well, and a heat exchanger installed in a pipe connecting the hot water well and the cold water well, comprising: an operation control unit that can switch the operation mode of the geothermal energy utilization system between a heating mode in which heating operation is performed by using water pumped from the hot water well and exchanging heat in the heat exchanger, and the water that has passed through the heat exchanger is returned to the cold water well; and a cooling mode in which cooling operation is performed by using water pumped from the cold water well and exchanging heat in the heat exchanger, and the water that has passed through the heat exchanger is returned to the hot water well; and a calculation unit that calculates the accumulated heat storage amount during a past heating operation period when the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period when the system was operated in the cooling mode. an operating state adjustment unit that adjusts the operating state of the geothermal energy utilization system so that a difference between an accumulated heat storage amount in a next heating operation period and an accumulated heat storage amount in a next cooling operation period is smaller than a difference between an accumulated heat storage amount in the past heating operation period and an accumulated heat storage amount in the past cooling operation period.

2. The control device according to claim 1, wherein the operation state adjustment unit heats water pumped from the hot water well using an auxiliary heat source provided separately from the heat exchanger during the next heating operation period when the accumulated heat storage amount during the past cooling operation period is greater than the accumulated heat storage amount during the past heating operation period.

3. The control device according to claim 1, wherein the operation state adjustment unit cools the water pumped from the cold water well using an auxiliary heat source provided separately from the heat exchanger during the next cooling operation period if the accumulated heat storage amount during the past heating operation period is greater than the accumulated heat storage amount during the past cooling operation period.

4. The control device according to claim 1, wherein the operating state adjustment unit adjusts the operating state of the geothermal energy utilization system so that the accumulated heat storage amount in the next cooling operation period is smaller when the accumulated heat storage amount in the past cooling operation period is greater than the accumulated heat storage amount in the past heating operation period.

5. The control device according to claim 4, wherein the operation state adjustment unit reduces the operation time in the cooling mode in the next cooling operation period.

6. The control device according to claim 4 or 5, wherein the operating condition adjustment unit reduces the pumping volume in the cold water well and the return water volume in the hot water well.

7. The control device according to claim 1, wherein the operating state adjustment unit adjusts the operating state of the geothermal energy utilization system so that the accumulated heat storage amount in the next heating operation period is smaller when the accumulated heat storage amount in the past heating operation period is greater than the accumulated heat storage amount in the past cooling operation period.

8. The control device according to claim 7, wherein the operation state adjustment unit reduces the operation time in the heating mode in the next heating operation period.

9. The control device according to claim 7 or 8, wherein the operating condition adjustment unit reduces the pumping volume in the hot water well and the return water volume in the cold water well.

10. A control device as claimed in any one of claims 1 to 5, 7 and 8, wherein the operation state adjustment unit sets the return water temperature to the cold water well during the next heating operation period and the return water temperature to the hot water well during the next cooling operation period based on the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period.

11. A geothermal energy utilization system comprising: a control device according to any one of claims 1 to 5, 7, and 8; and the heat source well facility.

12. A control method which switches the operating mode of a geothermal energy utilization system between a heating mode in which heating operation is performed by heat exchange using water pumped from a hot water well and the heat-exchanged water is returned to a cold water well, and a cooling mode in which cooling operation is performed by heat exchange using water pumped from the cold water well and the heat-exchanged water is returned to the hot water well, calculates the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode, and adjusts the operating state of the geothermal energy utilization system so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

13. A program that causes a computer to switch the operating modes of a geothermal energy utilization system between a heating mode in which heating operation is performed by heat exchange using water pumped from a hot water well and the heat-exchanged water is returned to a cold water well, and a cooling mode in which cooling operation is performed by heat exchange using water pumped from the cold water well and the heat-exchanged water is returned to the hot water well; calculate the accumulated heat storage amount during a past heating operation period in which the system was operated in the heating mode, and the accumulated heat storage amount during a past cooling operation period in which the system was operated in the cooling mode; and adjust the operating state of the geothermal energy utilization system so that the difference between the accumulated heat storage amount during the next heating operation period and the accumulated heat storage amount during the next cooling operation period is smaller than the difference between the accumulated heat storage amount during the past heating operation period and the accumulated heat storage amount during the past cooling operation period.

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