Refrigeration cycle apparatus
Patent Information
- Application Number
- PCT/JP2026/011515
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-23
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026011515_01102026_PF_FP_ABST
Abstract
Description
Refrigeration cycle device
[0001] The present invention relates to a refrigeration cycle device that uses geothermal heat.
[0002] In a refrigeration cycle device using geothermal heat, there is known a geothermal heat utilization device in which a geothermal heat exchanger and a heat source heat pump (air source heat pump) are connected to a circulating water line (for example, Patent Document 1). In this device, a temperature sensor is installed near the outlet of the geothermal heat exchanger, and the heat source heat pump is operated when the temperature of the circulating water falls below a threshold value. This can suppress a decrease in the coefficient of performance (COP) of the heat pump even when the amount of heat collected from the ground decreases (heat depletion).
[0003] Japanese Unexamined Patent Application Publication No. 2009-198102
[0004] It takes time from startup for the refrigerant circuit provided in the heat source heat pump to achieve the required capacity. Specifically, after startup, the refrigerant circuit needs to be operated to ensure the reliability of the compressor, for example, by operating the compressor at a low rotational speed until the discharge superheat reaches a predetermined value. Therefore, if the heat source heat pump is started after the temperature of the circulating water on the outlet side of the geothermal heat exchanger falls below the threshold as in the conventional art, there will be a period in which the required capacity cannot be obtained, which may lead to a decrease in comfort.
[0005] An object of the present invention is to provide a refrigeration cycle device that can suppress a decrease in comfort even when the amount of heat collected from the ground decreases.
[0006] To achieve the above objective, a refrigeration cycle apparatus according to one aspect of the present invention comprises an air conditioning unit, a heat transfer medium supplied to the air conditioning unit, a geothermal heat exchanger that exchanges heat between the heat transfer medium and soil, an air heat source unit that exchanges heat between the heat transfer medium and outside air, and a control device that controls the air conditioning unit and the air heat source unit. The control device includes a capacity acquisition unit that acquires the required capacity, which is the capacity necessary for the air conditioning unit to perform air conditioning operation; a heat extraction limit acquisition unit that acquires the upper limit of the amount of heat that the geothermal heat exchanger can extract from the soil; and an operation determination unit that compares the required capacity and the heat extraction limit to determine whether or not to operate the air heat source unit.
[0007] According to one aspect of the present invention, even if the amount of heat extracted from the ground decreases, a decrease in comfort can be suppressed.
[0008] This is a refrigerant circuit diagram showing an example of the schematic configuration of a refrigeration cycle device according to one embodiment of the present invention. This is a flowchart showing an example of the control flow of a refrigeration cycle device according to one embodiment of the present invention. This is a diagram illustrating processing example 1 in the control of a refrigeration cycle device according to one embodiment of the present invention, and is a graph schematically showing an example of the change in the temperature of the heat medium at the outlet of the ground heat exchanger with respect to the operating time of the refrigeration cycle device. This is a diagram illustrating processing example 3 in the control of a refrigeration cycle device according to one embodiment of the present invention, and is a graph schematically showing an example of the change in the temperature of the heat medium at the outlet of the ground heat exchanger with respect to the operating time of the operating mode, obtained in the heat extraction upper limit measurement operation mode performed to determine the heat extraction upper limit. This is a diagram illustrating processing example 4 in the control of a refrigeration cycle device according to one embodiment of the present invention, and is a graph schematically showing an example of the change in the temperature of the heat medium at the outlet of the ground heat exchanger with respect to the operating time of the refrigeration cycle device, used to find a relational expression for determining the start timing of operation of the air heat source unit. This is a diagram illustrating processing example 5 in the control of a refrigeration cycle device according to one embodiment of the present invention, and is a graph schematically showing an example of the change in the temperature of the heat medium at the outlet of the ground heat exchanger with respect to the operating time of the refrigeration cycle device, used to find a relational expression for determining the start timing of operation of the air heat source unit. This figure illustrates a processing example 6 in the control of a refrigeration cycle device according to one embodiment of the present invention, and is a schematic graph showing an example of the effect of the thermal conductivity of the soil on the temperature characteristics of the heat transfer medium at the outlet of the ground heat exchanger with respect to the operating time of the refrigeration cycle device.
[0009] The embodiments of the present invention illustrate apparatus and methods for realizing the technical idea of the present invention, and the technical idea of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.
[0010] [Configuration of the Refrigeration Cycle System] A refrigeration cycle system according to one embodiment of the present invention will be described using Figures 1 to 7. First, the configuration of the refrigeration cycle system according to this embodiment will be described using Figure 1. Figure 1 is a refrigerant circuit diagram showing an example of the schematic configuration of the refrigeration cycle system in this embodiment.
[0011] As shown in Figure 1, the refrigeration cycle device 1 comprises air conditioning units 11a and 11b, a heat transfer medium 12 supplied to the air conditioning units 11a and 11b, a geothermal heat exchanger 13 that exchanges heat between the heat transfer medium 12 and the soil 2, an air heat source unit 14 that exchanges heat between the heat transfer medium 12 and the outside air, and a control device 15 that controls the air conditioning units 11a and 11b and the air heat source unit 14.
[0012] The refrigeration cycle device 1 includes a heat transfer medium piping 10 that connects the air conditioning units 11a and 11b, the ground heat exchanger 13, and the air heat source unit 14. In Figure 1, for ease of understanding, the heat transfer medium 12 flowing through the heat transfer medium piping 10 is illustrated with arrows. As shown in Figure 1, the multiple air conditioning units 11a and 11b are connected in parallel in the direction of flow of the heat transfer medium 12. In this embodiment, water is used as the heat transfer medium 12, but other heat transfer mediums may also be used.
[0013] The heat transfer medium piping 10 is positioned between the inlet 131 and outlet 132 of the underground heat exchanger 13. An air heat source unit 14 and air conditioning units 11a and 11b are provided along the heat transfer medium piping 10. The heat transfer medium piping 10 branches upstream of the heat exchanger 111 provided in the air conditioning unit 11a and connects to the air conditioning unit 11b, and is formed to merge downstream of the heat exchanger 111. As a result, the heat transfer medium 12 flowing out from the outlet 132 of the underground heat exchanger 13 flows through the heat transfer medium piping 10 to the air heat source unit 14 and air conditioning units 11a and 11b, and flows into the underground heat exchanger 13 from the inlet 131.
[0014] In addition to the air heat source unit 14 and the air conditioning units 11a and 11b, the heat transfer fluid piping 10 also includes a circulation pump 17, a three-way valve 18a, a flow control valve 19, and a three-way valve 18b, located on the outlet 132 side of the ground heat exchanger 13. Part of the heat transfer fluid piping 10 is also located between the three-way valves 18a and 18b. The circulation pump 17 is controlled, for example, by a control device 15, and circulates the heat transfer fluid 12 through the heat transfer fluid piping 10 and the ground heat exchanger 13.
[0015] The three-way valve 18a has inlets and outlets for the heat transfer medium 12 on the outlet 132 side of the ground heat exchanger 13, the air heat source unit 14 side, and the three-way valve 18b side. The three-way valve 18b has inlets and outlets for the heat transfer medium 12 on the three-way valve 18a side, the air heat source unit 14 side, and the air conditioning unit 11a side. When the air heat source unit 14 is not operating, the three-way valve 18a connects the outlet 132 side of the ground heat exchanger 13 to the three-way valve 18b side, and the three-way valve 18b connects the three-way valve 18a side to the air conditioning unit 11a side. As a result, when the air heat source unit 14 is not operating, the heat transfer medium 12 does not flow to the air heat source unit 14 but circulates through the heat transfer medium piping 10 and the ground heat exchanger 13. Hereinafter, the state in which the three-way valves 18a and 18b are switched so that the three-way valve 18a connects the outlet 132 side of the ground heat exchanger 13 to the three-way valve 18b side, and the three-way valve 18b connects the three-way valve 18a side to the air conditioning unit 11a side will be referred to as "switching state α".
[0016] On the other hand, when the air heat source unit 14 is operating, the three-way valve 18a connects the outlet 132 side of the ground heat exchanger 13 to the air heat source unit 14 side, and the three-way valve 18b connects the air heat source unit 14 side to the air conditioning unit 11a side. As a result, when the air heat source unit 14 is operating, the heat transfer medium 12 flows through the heat transfer medium piping 10 while flowing to the air heat source unit 14. Hereinafter, the state in which the three-way valves 18a and 18b are switched so that the three-way valve 18a connects the outlet 132 side of the ground heat exchanger 13 to the air heat source unit 14 side, and the three-way valve 18b connects the air heat source unit 14 side to the air conditioning unit 11a side will be referred to as "switched state β". The three-way valves 18a and 18b are controlled by the control device 15 to switch the flow direction of the heat transfer medium 12 flowing through the heat transfer medium piping 10.
[0017] The flow control valve 19 is controlled by the control device 15 to adjust the flow rate of the heat transfer medium 12 flowing through the heat transfer medium piping 10. The flow control valve 19 is not required.
[0018] The refrigeration cycle device 1 includes a plurality of (two in this embodiment) air conditioning units 11a, 11b, but it may also include one air conditioning unit or three or more air conditioning units.
[0019] Air conditioning units 11a and 11b have the same configuration. Therefore, the configurations of air conditioning units 11a and 11b will be explained using air conditioning unit 11a as an example.
[0020] As shown in Figure 1, the air conditioning unit 11a is capable of both cooling and heating operation. The air conditioning unit 11a includes heat exchangers 111 and 112, a compressor 113, a four-way valve 114, an expansion valve 115, and a room temperature sensor 116. The four-way valve 114 is located on the discharge side of the compressor 113. An accumulator may be located on the suction side of the compressor 113. The air conditioning unit 11a includes a blower (not shown) for supplying air from the room in which the air conditioning unit 11a is located to the heat exchanger 112, and a drive motor (not shown) for driving the blower.
[0021] The heat exchanger 111 is, for example, a plate-type heat exchanger and has a heat transfer medium channel 111a connected to the heat transfer medium piping 10 and a refrigerant channel 111b through which the refrigerant used for heat exchange in the heat exchanger 111 flows. Therefore, in the heat exchanger 111, heat is exchanged between the heat transfer medium 12 flowing from the heat transfer medium piping 10 into the heat transfer medium channel 111a and the refrigerant flowing through the refrigerant channel 111b.
[0022] The room temperature sensor 116 is located inside the air conditioning unit 11a. The room temperature sensor 116 detects the temperature of the indoor air drawn into the air conditioning unit 11a before it passes through the heat exchanger 112.
[0023] The ground heat exchanger 13 is buried in the soil 2 and connected to the heat transfer medium piping 10 by an inlet 131 and an outlet 132. The outlet 132 of the ground heat exchanger 13 is connected to the air heat source unit 14 via a circulation pump 17 and a three-way valve 18a, and the inlet 131 of the ground heat exchanger 13 is connected to the air heat source unit 14 via an air conditioning unit 11a, a three-way valve 18b and a flow control valve 19. Therefore, the ground heat exchanger 13 and the air heat source unit 14 are connected in series with the parallel-connected air conditioning units 11a and 11b in the direction in which the heat transfer medium 12 flows when the three-way valves 18a and 18b are in the switched state β.
[0024] The air heat source unit 14 operates together with the ground heat exchanger 13 to heat or cool the heat transfer medium 12. During periods when the air conditioning units 11a and 11b are operating in heating mode (for example, in winter), the air heat source unit 14 performs an operation to heat the heat transfer medium 12 flowing through the heat transfer medium piping 10. Furthermore, during periods when the air conditioning units 11a and 11b are operating in cooling mode (for example, in summer), the air heat source unit 14 performs an operation to cool the heat transfer medium 12 flowing through the heat transfer medium piping 10.
[0025] In other words, when the air conditioning units 11a and 11b are operating in heating mode, the air heat source unit 14 absorbs heat from the outside air to heat the heat transfer medium 12. Conversely, when the air conditioning units 11a and 11b are operating in cooling mode, the air heat source unit 14 releases heat to the outside air to cool the heat transfer medium 12.
[0026] The air heat source unit 14 includes heat exchangers 141 and 142, a compressor 143, a four-way valve 144, and an expansion valve 145. The four-way valve 144 is located on the discharge side of the compressor 143. An accumulator may be located on the suction side of the compressor 143. The air heat source unit 14 also includes a blower (not shown) for supplying outside air to the heat exchanger 142, and a drive motor (not shown) for driving the blower.
[0027] The heat exchanger 141 is, for example, a plate-type heat exchanger and has a heat transfer medium channel 141a connected to the heat transfer medium piping 10 and a refrigerant channel 141b through which the refrigerant used for heat exchange in the air heat source unit 14 flows. Therefore, in the heat exchanger 141, heat is exchanged between the heat transfer medium 12 flowing from the heat transfer medium piping 10 into the heat transfer medium channel 141a and the refrigerant flowing through the refrigerant channel 141b.
[0028] As shown in Figure 1, the control device 15 includes a capacity acquisition unit 151, a heat extraction upper limit acquisition unit 152, an operation determination unit 153, and a storage unit 154. The control device 15 is, for example, a computer and is composed of, for example, one or more central processing units (CPUs) or microprocessing units (MPUs). A part of the control device 15 functions as a functional element or functional unit. The control device 15 executes an air conditioning control program stored in the storage unit 154 as one of its computer programs, so that the part that functions as a functional element or functional unit functions as the capacity acquisition unit 151, the heat extraction upper limit acquisition unit 152, and the operation determination unit 153.
[0029] The capacity acquisition unit 151 acquires the required capacity, which is the capacity necessary for the air conditioning units 11a and 11b to perform air conditioning operation. The capacity acquisition unit 151 acquires the required capacity based on the number and capacity information of the air conditioning units provided in the refrigeration cycle device 1, and the indoor load, which is the load during air conditioning operation of the air conditioning units. In this embodiment, the refrigeration cycle device 1 is equipped with two air conditioning units 11a and 11b. For example, the storage unit 154 stores the capacity information of each of the air conditioning units 11a and 11b. Here, the capacity information is unique information predetermined for each model of air conditioning unit 11a and 11b, and is, for example, the refrigeration capacity (e.g., rated capacity) that the air conditioning units 11a and 11b exhibit per unit time under predetermined conditions, or information correlated with the heat transfer area of the heat exchanger 111 provided in each of the air conditioning units 11a and 11b. The capacity acquisition unit 151 calculates the indoor load from the temperature difference between the set temperature set by the user for the air conditioning units 11a and 11b and the room temperature obtained from the room temperature sensors 116 provided in each of the air conditioning units 11a and 11b. Based on the capacity information read from the storage unit 154 and the calculated indoor load, the capacity acquisition unit 151 acquires the required capacity for each of the air conditioning units 11a and 11b. The required capacity acquired by the capacity acquisition unit 151 corresponds to the amount of heat required for the air conditioning operation of the air conditioning units 11a and 11b. The refrigeration cycle device 1 can set the capacity required for the current air conditioning operation of the air conditioning units 11a and 11b as the required capacity.
[0030] The heat extraction limit acquisition unit 152 acquires the heat extraction limit amount, which is the upper limit of the amount of heat that the geothermal heat exchanger 13 can extract from the soil 2. The heat extraction limit acquisition unit 152 may acquire a value predetermined in a test as the heat extraction limit amount, or it may acquire the heat extraction limit amount based on past operating data.
[0031] The operation determination unit 153 compares the required capacity with the heat extraction limit to determine whether or not to operate the air heat source unit 14. The heat extraction limit is the upper limit of the amount of heat that the ground heat exchanger 13 can extract from the soil 2. The required capacity corresponds to the amount of heat that the air conditioning units 11a and 11b need to air condition their respective rooms. Therefore, if the heat extraction limit is greater than the required capacity, the amount of heat extracted by the ground heat exchanger 13 from the soil 2 is sufficient to supply the amount of heat that the air conditioning units 11a and 11b need to air condition their respective rooms. In other words, the refrigeration cycle device 1 can use the soil 2 as a heat source to enable the air conditioning units 11a and 11b to air condition their respective rooms. On the other hand, if the heat extraction limit is less than the required capacity, the soil 2 cannot supply the amount of heat that the air conditioning units 11a and 11b need to air condition their respective rooms.
[0032] Therefore, the operation determination unit 153 determines that the operation of the air heat source unit 14 is unnecessary if the maximum heat extraction amount obtained by the heat extraction limit acquisition unit 152 is greater than the required capacity obtained by the capacity acquisition unit 151. On the other hand, the operation determination unit 153 determines that the operation of the air heat source unit 14 is necessary to replenish the amount of heat insufficient for air conditioning operation by the air conditioning units 11a and 11b if the maximum heat extraction amount obtained by the heat extraction limit acquisition unit 152 is smaller than the required capacity obtained by the capacity acquisition unit 151. In this way, the refrigeration cycle device 1 can appropriately control the air heat source unit 14 to either an ON state (operating state, i.e., running state) or an OFF state (stopped state) so as to be able to supply the amount of heat necessary to air condition the room by comparing the required capacity of the air conditioning units 11a and 11b with the maximum heat extraction amount.
[0033] The temperature sensor 16a is located near the inlet 131 of the ground heat exchanger 13. The temperature sensor 16a detects the temperature of the heat transfer medium 12 flowing from the heat transfer medium piping 10 into the ground heat exchanger 13. The temperature sensor 16a transmits the detected temperature value to the control device 15.
[0034] The temperature sensor 16b is located near the outlet 132 of the ground heat exchanger 13. The temperature sensor 16b detects the temperature of the heat transfer medium 12 flowing from the ground heat exchanger 13 into the heat transfer medium piping 10. The temperature sensor 16b transmits the detected temperature value to the control device 15.
[0035] [Operation of the Refrigeration Cycle System] The operation of the refrigeration cycle system 1 according to this embodiment will be explained with reference to Figure 1 and using Figure 2. Figure 2 is a flowchart showing an example of the operation flow of the refrigeration cycle system 1. The operation of the refrigeration cycle system 1 shown in Figure 2 is controlled by the control device 15.
[0036] The control device 15 (see Figure 1) starts the operation of the refrigeration cycle device 1 (see Figure 1) by operating the circulation pump 17 (see Figure 1) after setting the state of the three-way valves 18a and 18b (see Figure 1) to state α. As shown in Figure 2, when the control device 15 starts the operation of the refrigeration cycle device 1, it first determines in step ST10 whether or not the air conditioning units 11a and 11b (see Figure 1) have started operating. If the control device 15 determines that at least one of the air conditioning units 11a and 11b has started operating (Yes in step ST10), it proceeds to the process of step ST20. On the other hand, if the control device 15 determines that neither of the air conditioning units 11a and 11b has started operating (No in step ST10), it repeats the process of step ST10. The control device 15 repeatedly executes the process of step ST10 at predetermined time intervals unless it proceeds to the process of step ST20.
[0037] For example, when the air conditioning units 11a and 11b perform cooling operation, the refrigerant, which has been compressed to a high temperature and pressure by the compressor 113 (see Figure 1), flows through the refrigerant flow path 111b (see Figure 1) of the heat exchanger 111 via the four-way valve 114 (see Figure 1). The high temperature and pressure refrigerant flowing through the refrigerant flow path 111b dissipates heat by exchanging heat with the heat transfer medium 12 (see Figure 1) flowing through the heat transfer medium flow path 111a (see Figure 1) of the heat exchanger 111.
[0038] The refrigerant that has dissipated heat by passing through the heat exchanger 111 is depressurized by the expansion valve 115 (see Figure 1). The depressurized refrigerant then flows through the heat exchanger 112. The heat exchanger 112 functions as an evaporator, and the refrigerant flowing through the heat exchanger 112 exchanges heat with the room air blown by a fan (not shown) and absorbs heat. The room air that has absorbed heat from the refrigerant flowing through the heat exchanger 112 is cooled. The heat-absorbing refrigerant returns to the compressor 113 and is compressed again to high temperature and high pressure. In other words, the air conditioning units 11a and 11b are configured with a refrigerant circuit in which, in cooling operation, the refrigerant flows in the following order: compressor 113, four-way valve 114, heat exchanger 111 (which functions as a condenser), expansion valve 115, heat exchanger 112 (which functions as an evaporator), and compressor 113.
[0039] When the air conditioning units 11a and 11b perform heating operation, the refrigerant flows in the reverse direction from the cooling operation by switching the four-way valve 114. During heating operation, the refrigerant, which has been compressed to high temperature and pressure by the compressor 113, flows through the heat exchanger 112 via the four-way valve 114. The heat exchanger 112 functions as a condenser, and the high temperature and pressure refrigerant flowing through the heat exchanger 112 releases heat by exchanging heat with the indoor air blown by the fan, and the indoor air that has exchanged heat with the high temperature and pressure refrigerant is warmed. The refrigerant that has released heat after passing through the heat exchanger 112 is depressurized by the expansion valve 115. The depressurized refrigerant flows through the refrigerant flow path 111b of the heat exchanger 111. The refrigerant flowing through the refrigerant flow path 111b exchanges heat with the heat transfer medium 12 flowing through the heat transfer medium flow path 111a of the heat exchanger 111 and absorbs heat. The refrigerant that has absorbed heat returns to the compressor 113 and is compressed to high temperature and pressure again.
[0040] In step ST20, the capacity acquisition unit 151 (see Figure 1) provided in the control device 15 acquires the required capacity based on the number of air conditioning units 11a and 11b (two in this embodiment), capacity information, and the indoor load which is the load during air conditioning operation, and then proceeds to the processing in step ST30.
[0041] In step ST30, the heat extraction limit acquisition unit 152 (see Figure 1) provided in the control device 15 acquires the heat extraction limit amount, which is the upper limit of the amount of heat that the geothermal heat exchanger 13 can extract from the soil 2 (see Figure 1), and proceeds to the process in step ST40.
[0042] In step ST40, the operation determination unit 153 (see FIG. 1) provided in the control device 15 compares the required capacity obtained by the capacity acquisition unit 151 in the processing of step ST20 with the maximum heat collection amount obtained by the maximum heat collection acquisition unit 152 in the processing of step ST30, and determines whether the required capacity is larger than the maximum heat collection amount. If the required capacity is larger than the maximum heat collection amount (Yes in step ST40), the operation determination unit 153 proceeds to the processing of step ST50. On the other hand, if the required capacity is equal to or smaller than the maximum heat collection amount (No in step ST40), the operation determination unit 153 proceeds to the processing of step ST60.
[0043] In step ST50, the control device 15 determines whether the air heat source unit 14 has already started operation and is in operation. If the control device 15 determines that the air heat source unit 14 is in operation (Yes in step ST50), it proceeds to the processing of step ST60. On the other hand, if the control device 15 determines that the air heat source unit 14 is not in operation (No in step ST50), it proceeds to the processing of step ST80.
[0044] Here, when the air heat source unit 14 is not in operation (No in step ST50), the flow of the heat medium 12 is as follows. When the air conditioning units 11a and 11b perform cooling operation, the heat medium 12, which is heated (releases heat from the refrigerant) when flowing through the heat medium flow path 111a of the heat exchanger 111, flows into the underground heat exchanger 13 from the inlet 131 of the underground heat exchanger 13, exchanges heat with the soil 2, and is cooled. The heat medium 12 flowing out from the outlet 132 of the underground heat exchanger 13 is sucked into the circulation pump 17, sent to the heat exchanger 111, heated again by the refrigerant flowing through the refrigerant flow path 111b after passing through the heat medium flow path 111a, and then flows out toward the underground heat exchanger 13.
[0045] When the air conditioning units 11a and 11b perform heating operation, the heat transfer medium 12, which is cooled (heat absorbed by the refrigerant) as it flows through the heat transfer medium channel 111a of the heat exchanger 111, flows into the underground heat exchanger 13 from the inlet 131 of the underground heat exchanger 13, and is heated by exchanging heat with the soil 2. The heat transfer medium 12 that flows out from the outlet 132 of the underground heat exchanger 13 is sucked into the circulation pump 17, sent to the heat exchanger 111, and after passing through the heat transfer medium channel 111a and being cooled again by the refrigerant flowing through the refrigerant channel 111b, it flows out towards the underground heat exchanger 13.
[0046] In step ST60, the control device 15 determines whether the air conditioning units 11a and 11b have finished operating. If the control device 15 determines that both air conditioning units 11a and 11b have finished operating (Yes in step ST60), it proceeds to the process in step ST70. On the other hand, if the control device 15 determines that at least one of the air conditioning units 11a and 11b is still operating (No in step ST60), it repeats the process in step ST60. The control device 15 repeatedly executes the process in step ST60 at predetermined time intervals unless it proceeds to the process in step ST70.
[0047] In step ST70, the control device 15 stops the circulation pump 17 and then stops the refrigeration cycle device 1.
[0048] In step ST80, the control device 15 determines the timing to start the operation of the air heat source unit 14 on the basis of the temperature of the heat medium 12 flowing out from the underground heat exchanger 13, the heat collection amount which is the amount of heat collected from the soil 2 by the underground heat exchanger 13, and the preliminary operation of the air heat source unit 14, and proceeds to the process of step ST90. Here, the preliminary operation of the air heat source unit 14 is an operation performed after the air heat source unit 14 is activated until a predetermined capacity is obtained, as in Processing Example 5 described later, for ensuring the reliability of the compressor 143. When the air heat source unit 14 operates, power consumption for the air heat source unit 14 increases, which may reduce the operating efficiency of the entire refrigeration cycle device 1. For this reason, the refrigeration cycle device 1 is operated as much as possible by the heat source of the underground heat of the soil 2 alone by adjusting the operation start timing of the air heat source unit 14. Accordingly, the refrigeration cycle device 1 can suppress a decrease in operating efficiency. After determining the timing, the control device 15 calculates a standby time until the timing.
[0049] In step ST90, the control device 15 determines whether it is the timing to start the operation of the air heat source unit 14. If the control device 15 determines that the standby time calculated in step ST80 has elapsed and it is the operation start timing determined in step ST80 (Yes in step ST90), the process proceeds to step ST100. On the other hand, if the control device 15 determines that the standby time calculated in step ST80 has not elapsed and it is not the operation start timing determined in step ST80 (No in step ST90), the process of step ST90 is repeated.
[0050] In step ST100, the control device 15 switches the state of the three-way valves 18a and 18b to the switching state β, and proceeds to the process of step ST110.
[0051] In step ST110, the control device 15 starts the operation of the air heat source unit 14, and proceeds to the process of step ST60.
[0052] For example, when the air heat source unit 14 operates to cool the heat transfer medium 12 (i.e., when the air conditioning units 11a and 11b perform cooling operation), the refrigerant, which has been compressed to high temperature and high pressure by the compressor 143 (see Figure 1), flows through the four-way valve 144 (see Figure 1) to the heat exchanger 142 (see Figure 1). The heat exchanger 142 functions as a condenser, and the high temperature and high pressure refrigerant flowing through the heat exchanger 142 dissipates heat by exchanging heat with outside air blown by a blower (not shown). The refrigerant that has dissipated heat by passing through the heat exchanger 142 is depressurized by the expansion valve 145 (see Figure 1). The depressurized refrigerant flows through the refrigerant flow path 141b (see Figure 1) of the heat exchanger 141. The refrigerant flowing through the refrigerant flow path 141b exchanges heat with the heat transfer medium 12 flowing through the heat transfer medium flow path 141a (see Figure 1) of the heat exchanger 141, absorbing heat and cooling the heat transfer medium 12. The refrigerant that has absorbed heat returns to the compressor 143 and is compressed again to high temperature and pressure.
[0053] When heating the heat transfer medium 12 (i.e., when the air conditioning units 11a and 11b perform heating operation), the refrigerant flows in the reverse direction compared to when cooling the heat transfer medium 12, due to the switching of the four-way valve 144. The refrigerant, which has been compressed to high temperature and pressure by the compressor 143, flows through the refrigerant flow path 141b of the heat exchanger 141 via the four-way valve 144. The high temperature and pressure refrigerant flowing through the refrigerant flow path 141b exchanges heat with the heat transfer medium 12 flowing through the heat transfer medium flow path 141a of the heat exchanger 141, releasing heat and heating the heat transfer medium 12. The refrigerant that has released heat after passing through the heat exchanger 141 is depressurized by the expansion valve 145. The depressurized refrigerant flows through the heat exchanger 142. The heat exchanger 142 functions as an evaporator, and the refrigerant flowing through the heat exchanger 142 exchanges heat with the outside air blown by the fan and absorbs heat. The refrigerant that has absorbed heat returns to the compressor 143 and is compressed again to high temperature and pressure.
[0054] [Processing Example] The process for obtaining the maximum heat extraction amount in the refrigeration cycle device according to this embodiment will be explained using Figures 3 to 7 with reference to Figures 1 and 2.
[0055] (Processing Example 1) As Processing Example 1, the process for obtaining the maximum heat extraction amount in the refrigeration cycle device 1 according to this embodiment will be explained with reference to Figures 1 and 2 and with reference to Figure 3. This processing example is characterized in that the heat extraction limit acquisition unit 152 acquires a value predetermined by testing as the maximum heat extraction amount.
[0056] Figure 3 is a schematic graph showing an example of the change in the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the operation mode, which is obtained in the heat extraction limit measurement operation mode that is performed to determine the heat extraction limit during heating operation. "HEA_S", "HEA_M", and "HEA_L" shown in Figure 3 all represent the temperature characteristics of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 when the operation mode is continued with a constant heat extraction amount. Temperature characteristic HEA_S is the characteristic when the amount of heat extracted is smaller than that of temperature characteristics HEA_M and temperature characteristics HEA_L (i.e., the smallest amount of heat extracted among the three). Temperature characteristic HEA_L is the characteristic when the amount of heat extracted is larger than that of temperature characteristics HEA_S and temperature characteristics HEA_M (i.e., the largest amount of heat extracted among the three). The temperature characteristic HEA_M represents a heat extraction amount that is approximately midway between the heat extraction amount in temperature characteristic HEA_S and the heat extraction amount in temperature characteristic HEA_L. "HTth" shown in Figure 3 indicates the minimum temperature (threshold temperature) of the heat source required to obtain the necessary capacity of the air conditioning units 11a and 11b. The horizontal axis of the graph shown in Figure 3 represents the operating time of the operating mode, and the vertical axis of the graph shown in Figure 3 represents the temperature (water temperature) of the heat transfer medium 12 (water in this example) at the outlet 132 of the ground heat exchanger 13.
[0057] As shown by the temperature characteristics HEA_S, HEA_M, and HEA_L in Figure 3, the temperature of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 decreases monotonically with respect to the operating time in the heat extraction upper limit measurement operation mode. The larger the amount of heat extracted from the soil 2, the more heat is removed from the soil 2 as the operation mode continues. Therefore, the temperature change of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 becomes larger as the amount of heat extracted increases. Also, if the amount of heat extracted during the operation of the heat extraction upper limit measurement operation mode is constant, the temperature of the heat transfer medium 12 flowing out of the geothermal heat exchanger 13 decreases as the operation mode continues. However, the amount of decrease decreases as the operating time of the operation mode progresses, and the temperature converges to a predetermined value corresponding to the amount of heat extracted.
[0058] Therefore, as shown in Figure 3, even if the temperature value of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 is approximately the same at the start of the heat extraction upper limit measurement operation mode, the larger the amount of heat extracted, the more likely it is to fall below the threshold temperature HTth as the operation mode continues. In other words, even if the temperature value of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 is approximately the same at the start of the heat extraction upper limit measurement operation mode, the smaller the amount of heat extracted, the less likely it is to fall below the threshold temperature HTth as the operation mode continues. In the example shown in Figure 3, only the temperature of the heat transfer medium corresponding to the temperature characteristic HEA_L when the amount of heat extracted is largest falls below the threshold temperature HTth.
[0059] Furthermore, the rate of temperature change of the heat transfer medium 12 flowing out of the geothermal heat exchanger 13 is the same with respect to the operating time of the heat extraction upper limit measurement operation mode, regardless of the temperature value (initial value) at the start of the operation mode. In other words, the temperature characteristics HEA_S, HEA_M, and HEA_L shift to the lower temperature side overall as the initial value decreases. Therefore, even if the amount of heat extracted is the same, the temperature of the heat transfer medium 12 flowing out of the geothermal heat exchanger 13 will converge to a lower temperature value as the temperature value at the start of the heat extraction upper limit measurement operation mode decreases.
[0060] The amount of heat extracted is the amount of heat exchanged in the ground heat exchanger 13, and can be calculated using the following formula (1): Amount of heat extracted = Temperature difference between the inlet and outlet of the ground heat exchanger 13 × Flow rate of the heat transfer medium ... (1) Also, since the amount of heat extracted is also the amount of heat exchanged in the heat exchangers 111 provided in the air conditioning units 11a and 11b (i.e., the amount of heat required for the air conditioning operation of the air conditioning units 11a and 11b (required capacity)), it can also be calculated using the following formula (2): Amount of heat extracted = Enthalpy difference between the inlet and outlet of the heat exchanger 111 provided in the air conditioning units 11a and 11b × Flow rate of the refrigerant ... (2)
[0061] The refrigeration cycle device 1 includes a temperature sensor 16a located near the inlet 131 of the geothermal heat exchanger 13, a temperature sensor 16b located near the outlet 132 of the geothermal heat exchanger 13, and a circulation pump 17. Therefore, the refrigeration cycle device 1 can obtain the temperature of the heat transfer medium 12 at the inlet 131 and outlet 132 of the geothermal heat exchanger 13 using the temperature sensors 16a and 16b. Furthermore, the refrigeration cycle device 1 can control the flow rate of the heat transfer medium 12 using the circulation pump 17. Therefore, in this embodiment, the amount of heat extracted is calculated using, for example, equation (1).
[0062] In this example, a predetermined test is performed before the refrigeration cycle device 1 is installed, and a table is created showing the relationship between the amount of heat extracted and the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13. In this example, the test is performed by, for example, a Thermal Response Test (TRT). Table 1 shows an example of such a table. The values shown in the table in Table 1 are for explanatory purposes only and are not values obtained from an actual thermal response test. The "Ground Outlet Temperature [°C]" shown in Table 1 indicates the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13.
[0063]
[0064] The temperature value stored in the "Ground Outlet Temperature [°C]" column of the table shown in Table 1 corresponds to the temperature at which the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 converges, assuming that heat extraction continues at the heat extraction amount shown in the "Heat Extraction Amount [kW]" column of Table 1. The convergence value of the ground outlet temperature relative to the heat extraction amount is obtained through tests conducted before the installation of the refrigeration cycle device 1, and the table shown in Table 1 is created. The created table is stored in the storage unit 154 (see Figure 2) provided in the control device 15.
[0065] The "Ground Outlet Temperature [°C]" in the table shown in Table 1 corresponds to the temperature value at which the temperature of the heat transfer medium 12 converges at the outlet 132 of the ground heat exchanger 13. Therefore, by referring to this table, it is possible to predict the temperature value at which the temperature of the heat transfer medium 12 converges at the outlet 132 of the ground heat exchanger 13 from the amount of heat extracted at the start of operation of the air conditioning units 11a and 11b.
[0066] In other words, by referring to the table shown in Table 1, it is possible to obtain the temperature at which the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 finally converges (the temperature in the "Ground Outlet Temperature [°C]" column in Table 1) based on the amount of heat extracted (i.e., required capacity) calculated when the air conditioning units 11a and 11b start operation.
[0067] As described above, the maximum heat extraction amount is the upper limit of the amount of heat that the ground heat exchanger 13 can extract from the soil 2. Therefore, the maximum heat extraction amount (unit: for example, "kilowatts (kW)") corresponds to the amount of heat that can be extracted so that the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 does not fall below the threshold temperature HTth, allowing the refrigeration cycle device 1 to continue operating. In other words, in the table shown in Table 1, the "amount of heat extracted [kW]" corresponding to the "ground outlet temperature [°C]" that is the same as or greater than and closest to the threshold temperature HTth corresponds to the maximum heat extraction amount. Therefore, by comparing the maximum heat extraction amount with the required capacity (the amount of heat extracted calculated at the start of operation of the air conditioning units 11a and 11b), it is possible to predict whether the heat transfer medium 12 can maintain a temperature higher than the threshold temperature HTth, regardless of the operating duration of the air conditioning units 11a and 11b.
[0068] In the refrigeration cycle device 1 according to this processing example, in the process of step ST30 shown in Figure 2, the heat extraction limit acquisition unit 152 (see Figure 1) acquires a value predetermined by a test as the heat extraction limit. That is, in step ST30, the heat extraction limit acquisition unit 152 acquires the amount of heat extracted that corresponds to the underground outlet temperature that is the same as or greater than and closest to the threshold temperature HTth, from among the heat extracted amounts stored in a table (see Table 1) that associates the amount of heat extracted obtained by a predetermined test (e.g., a thermal response test) with the underground outlet temperature, as the heat extraction limit. The operation determination unit 153 (see Figure 1) compares the heat extraction limit acquired in this way by the heat extraction limit acquisition unit 152 with the required capacity acquired by the capacity acquisition unit 151 (step ST20 shown in Figure 2) (step ST40 shown in Figure 2). As a result, the operation determination unit 153 can determine whether the air conditioning units 11a and 11b can perform air conditioning operation using only the heat medium 12 flowing from the ground heat exchanger 13 into the heat medium piping 10 as a heat source, regardless of the operating duration of the air conditioning units 11a and 11b (i.e., whether the operation of the air heat source unit 14 is necessary) (step ST50 shown in Figure 2).
[0069] (Processing Example 2) As Processing Example 2, the process for acquiring the maximum heat extraction amount in the refrigeration cycle device 1 according to this embodiment will be described with reference to Figures 1 and 2. The heat extraction limit acquisition unit in this processing example is characterized in that it acquires the maximum heat extraction amount based on past operating data.
[0070] In the above processing example 1, the table shown in Table 1 is created by a predetermined test performed before the installation of the refrigeration cycle device 1. In this processing example, the table is created by acquiring information necessary during the operation of the refrigeration cycle device. That is, at the time of shipment of the refrigeration cycle device 1, the table stored in the storage unit 154 has a predetermined value stored in the "heat extraction amount [kW]" column, but no value is stored in the "ground outlet temperature [°C]" column. During the air conditioning operation of the air conditioning units 11a and 11b, the heat extraction amount and the converged value of the temperature of the heat transfer medium at the outlet 132 of the ground heat exchanger 13 are acquired. Therefore, the acquired converged value is stored as the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 in the corresponding location in the "ground outlet temperature [°C]" column of the table stored in the storage unit 154.
[0071] In the refrigeration cycle device 1 according to this processing example, in the process of step ST30 shown in Figure 2, the heat extraction limit acquisition unit 152 (see Figure 1) acquires the heat extraction limit by referring to a table created by storing the temperature acquired during the air conditioning operation of the air conditioning units 11a and 11b (i.e., an example of past operating data) in the "ground outlet temperature [°C]" column, as described above. Thus, in this processing example, the heat extraction limit acquisition unit 152 acquires the heat extraction limit based on past operating data.
[0072] By setting the maximum heat extraction limit based on past operating data, it is possible to respond to short-term and long-term changes in ground temperature. As a result, the refrigeration cycle device 1 that acquires the maximum heat extraction limit using this processing example can set a threshold temperature that is suitable for the installation environment and can appropriately switch between operating and non-operating states of the air heat source unit 14.
[0073] If operation that significantly degrades the performance of the air conditioning units 11a and 11b is recorded, the recorded heat extraction amount may be set as the upper limit for heat extraction, and the air heat source unit 14 may be operated along with the refrigeration cycle device 1. In this case, the control device 15 may, for example, proceed to step ST100 after step ST40 shown in Figure 2, without executing the processes from step ST50 to step ST90. Furthermore, after executing such a process, the control device 15 may operate the air heat source unit 14 if it is predicted that the required capacity of the air conditioning units 11a and 11b will exceed the upper limit for heat extraction.
[0074] (Processing Example 3) As Processing Example 3, the process for acquiring the maximum heat extraction amount in the refrigeration cycle device 1 according to this embodiment will be explained with reference to Figures 1 and 2 and with reference to Figure 4. The heat extraction limit acquisition unit 152 in this processing example is characterized in that it acquires the maximum heat extraction amount based on past operating data, similar to Processing Example 2 above. However, in this processing example, unlike Processing Example 2 above, if the maximum heat extraction amount in the ground is unknown before starting operation of the refrigeration cycle device 1, the heat extraction limit measurement operation mode is performed after the refrigeration cycle device 1 is installed and before normal operation is performed to acquire the maximum heat extraction amount.
[0075] Figure 4 is a schematic graph showing an example of the change in the temperature (water temperature) of the heat transfer medium 12 (water in this example) at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the operation mode obtained in the heat extraction upper limit measurement operation mode. The terms "HEA_S", "HEA_M", and "HEA_L" shown in Figure 4 are the same as "HEA_S", "HEA_M", and "HEA_L" shown in Figure 3, so no explanation is given. The horizontal axis of the graph shown in Figure 4 represents the operating time of the operation mode, and the vertical axis of the graph shown in Figure 4 represents the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13.
[0076] As shown in Figure 4, in the heat extraction upper limit measurement operation mode in this processing example, for example, the amount of heat extracted is changed in steps, and the temperature value at which the underground outlet temperature (for example, the temperature of the heat transfer medium 12 at the outlet 132 of the underground heat exchanger 13) converges is recorded for each amount of heat extracted. The convergence temperature Tco_S is recorded from the temperature characteristic HEA_S when the minimum amount of heat extracted is set, the convergence temperature Tco_M is recorded from the temperature characteristic HEA_M when the intermediate amount of heat extracted is set, and the convergence temperature Tco_L is recorded from the temperature characteristic HEA_L when the maximum amount of heat extracted is set. The convergence temperatures Tco_S, Tco_M, and Tco_L are stored in the "Underground Outlet Temperature [°C]" field, corresponding to the same amount of heat extracted from the amount of heat extracted for which the temperature characteristics HEA_S, HEA_M, and HEA_L are obtained, and are stored in the storage unit 154, for example.
[0077] In the refrigeration cycle device 1 according to this processing example, in the process of step ST30 shown in Figure 2, the heat extraction limit acquisition unit 152 (see Figure 1) acquires the heat extraction limit by referring to a table created by storing the converged temperature (i.e., an example of past operating data) acquired in the heat extraction limit measurement operation mode as described above in the "underground outlet temperature [°C]" column. Thus, in this processing example, the heat extraction limit acquisition unit 152 acquires the heat extraction limit based on past operating data.
[0078] By setting the maximum heat extraction limit based on past operating data, it is possible to respond to short-term and long-term changes in underground temperature. As a result, the refrigeration cycle device 1 that acquires the maximum heat extraction limit using this processing example can achieve the same effect as the refrigeration cycle device 1 that acquires the maximum heat extraction limit using processing example 2.
[0079] (Processing Example 4) As Processing Example 4, the process for acquiring the maximum heat extraction amount in the refrigeration cycle device 1 according to this embodiment will be explained with reference to Figures 1 and 2, and with reference to Figure 5. This processing example is characterized in that the configuration of the table referenced by the heat extraction limit acquisition unit 152 differs from that of Processing Examples 1 to 3. Figure 5 is a schematic graph showing an example of the change in the temperature (water temperature) of the heat transfer medium 12 (water in this processing example) at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the ground heat exchanger 13, which is used when creating the table referenced when acquiring the maximum heat extraction amount. "HEA_S", "HEA_M", and "HEA_L" shown in Figure 5 are the same as "HEA_S", "HEA_M", and "HEA_L" shown in Figure 3, so their explanation will be omitted. In the graph shown in Figure 5, the horizontal axis represents the operating time, and the vertical axis represents the temperature (water temperature) of the heat transfer medium 12 (water in this example) at the outlet 132 of the ground heat exchanger 13.
[0080] In this processing example, the temperature characteristics showing the change in the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the ground heat exchanger 13 may be acquired during the operation of the refrigeration cycle device 1, as in processing example 2, or may be acquired by the heat extraction upper limit measurement operation mode, as in processing example 3.
[0081] As shown in Figure 5, in this processing example, the temperature characteristics HEA_S, HEA_M, and HEA_L are used to obtain the rate of change (i.e., the temperature slope) of the temperature of the heat medium 12 at time t2, a predetermined time after time t1, relative to the temperature of the heat medium 12 at the start of operation of the ground heat exchanger 13 (e.g., time t1). The rate of change Tcr_S is recorded from the temperature characteristic HEA_S when the minimum heat extraction amount is set, the rate of change Tcr_M is recorded from the temperature characteristic HEA_M when the intermediate heat extraction amount is set, and the rate of change Tcr_L is recorded from the temperature characteristic HEA_L when the maximum heat extraction amount is set.
[0082] Table 2 shows an example of a table referenced by the heat extraction upper limit acquisition unit 152. The values shown in the table in Table 2 are for explanatory purposes only and are not values obtained from actual thermal response tests.
[0083]
[0084] In Table 2, the "Heat Extraction Amount [kW]" and "Temperature Change Rate" columns store values related to the same temperature characteristic in the same row. For example, if the temperature characteristic when the heat extraction amount is 5 [kW] is temperature characteristic HEA_S and the temperature change rate Tcr_S is "4", then as shown in Table 2, "5" and "4" will be stored correspondingly in, for example, the second row of the "Heat Extraction Amount [kW]" and "Temperature Change Rate" columns of the table. The created table is stored in the storage unit 154 (see Figure 2) provided in the control device 15.
[0085] In the refrigeration cycle device 1 according to this processing example, in the process of step ST30 shown in Figure 2, the heat extraction upper limit acquisition unit 152 (see Figure 1) acquires the heat extraction upper limit amount by referring to the table shown in Table 2.
[0086] (Processing Example 5) As Processing Example 5, the process of determining the start timing of operation of the air heat source unit 14 in the refrigeration cycle device 1 according to this embodiment (step ST80) will be explained with reference to Figures 1 to 3 and with reference to Figure 6. In this processing example, the control device 15 is characterized in that it determines the timing for operating the air heat source unit 14 based on the temperature of the heat transfer medium 12 flowing out from the geothermal heat exchanger 13, the amount of heat extracted by the geothermal heat exchanger 13 from the soil 2, and the preliminary operation of the air heat source unit 14. Figure 6 is a graph showing the process of determining the timing for operating the air heat source unit 14 in relation to the temperature characteristics of the heat transfer medium 12. In Figure 6, "HEA_1" shows the predicted temperature characteristics of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 when the temperature of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 (initial temperature of soil 2) is a first temperature at the start of heat extraction (immediately after the start of operation of the circulation pump 17). In Figure 6, "HEA_2" shows the predicted temperature characteristics of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 when the initial temperature of soil 2 is a second temperature, which is lower than the first temperature. In the graph shown in Figure 6, the horizontal axis represents the operating time of the refrigeration cycle device 1, and the vertical axis represents the temperature of the heat transfer medium 12 (water in this example) at the outlet 132 of the geothermal heat exchanger 13 (water temperature in this example).
[0087] As a prerequisite for determining the timing of operating the air heat source unit 14, when heat is extracted beyond the upper limit of heat extraction, the time from the start of heat extraction until the temperature of the heat medium 12 falls below the threshold temperature HTth varies depending on the initial temperature of the soil 2 (see Figure 3). On the other hand, if the air conditioning units 11a and 11b can be operated using the heat medium 12, which has a temperature above the threshold temperature HTth of the heat medium 12, operating the air heat source unit 14 will unnecessarily increase the power consumption of the refrigeration cycle device 1. In order to improve the operating efficiency of the refrigeration cycle device 1, it is desirable to start operating the air heat source unit 14 at an appropriate timing.
[0088] The control device 15 creates a relationship between the amount of heat extracted and the initial temperature of the soil 2 based on the results of the test in processing example 1 (e.g., thermal response test), the normal operation of the air conditioning units 11a and 11b in processing example 2, the heat extraction upper limit measurement operation mode in processing example 3, or the temperature change rate of the heat medium in processing example 4, or a combination of these processing examples.
[0089] As shown in Figure 6, for example, the control device 15 predicts the temperature characteristics at a first temperature as temperature characteristic HEA_1 based on a relational expression created for the first temperature. Also, for example, the control device 15 predicts the temperature characteristics at a second temperature, which is lower than the first temperature, as temperature characteristic HEA_2 based on a relational expression created for the second temperature.
[0090] If the initial temperature of soil 2 is the first temperature, and the air conditioning operation of air conditioning units 11a and 11b continues, then, for example, based on the temperature characteristic HEA_1 shown in Figure 6, it is expected that at time Tth_1, after time t1 when the air conditioning units 11a and 11b started operation, the temperature of the heat transfer medium 12 will fall below the threshold temperature HTth. In other words, if the initial temperature of soil 2 at time t1 when the air conditioning units 11a and 11b started operation is the first temperature, the control device 15 predicts that after time Tth_1, the operating efficiency of air conditioning units 11a and 11b will decrease if the heat source is only soil 2.
[0091] Similarly, if the initial temperature of soil 2 is the second temperature, and the air conditioning operation of air conditioning units 11a and 11b continues, then, based on the temperature characteristic HEA_2 shown in Figure 6, for example, the temperature of the heat transfer medium 12 is expected to fall below the threshold temperature HTth at time Tth_2, after time t1 when the air conditioning units 11a and 11b started operation. In other words, if the initial temperature of soil 2 at time t1 when the air conditioning units 11a and 11b started operation is the second temperature, the control device 15 predicts that the operating efficiency of air conditioning units 11a and 11b will decrease from time Tth_2 onward if the heat source is only soil 2.
[0092] Incidentally, even if the air heat source unit 14 is controlled by the control device 15 to start operation, it requires a predetermined operating time from startup until it operates at a predetermined capacity. Therefore, in this processing example, the control device 15 starts the operation of the air heat source unit 14 at times ts_1 and ts_2, which are earlier by the operating time AT of the air heat source unit 14 than the times Tth_1 and Tth_2, when the temperature of the heat medium 12 is predicted to be lower than the threshold temperature HTth. As a result, the air heat source unit 14 operates at a predetermined capacity at times Tth_1 and Tth_2, and can assist the refrigeration cycle using the heat medium 12 as a heat source. Here, the operation for the operating time AT corresponds to the preliminary operation of the air heat source unit 14.
[0093] Furthermore, to enhance the effectiveness of the air heat source unit 14, the operating time AT of the air heat source unit 14 may be determined from the relationship between the ambient air temperature and the predicted required capacity, and the start time of the air heat source unit 14 may be determined and operation may begin. The required capacity of the air heat source unit 14 can be determined by subtracting the upper limit of heat extraction from the amount of heat extracted.
[0094] (Processing Example 6) As Processing Example 6, the determination process (step ST40) of whether or not to operate the air heat source unit 14 in the refrigeration cycle device 1 according to this embodiment will be explained with reference to Figures 1 and 2 and with reference to Figure 7. This processing example is characterized in that the thermal conductivity of the soil 2 is taken into consideration when determining the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13. Figure 7 is a schematic graph showing an example of the influence of the thermal conductivity of the soil 2 on the temperature characteristics of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the refrigeration cycle device 1. "HEA_h" and "HEA_l" in Figure 7 show the temperature characteristics of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 with respect to the operating time of the refrigeration cycle device 1. The temperature characteristic HEA_h is the characteristic when the amount of heat extracted is the same as that of the temperature characteristic HEA_l, and the thermal conductivity of the soil 2 is high. In the graph shown in Figure 7, the horizontal axis represents the operating time of the refrigeration cycle device 1, and the vertical axis represents the temperature of the heat transfer medium 12 (water in this example) at the outlet 132 of the ground heat exchanger 13 (water temperature in this example).
[0095] As shown in Figure 7, the temperature characteristic HEA_h tends to have a lower temperature of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 compared to the temperature characteristic HEA_l, even when the operation of the refrigeration cycle device 1 continues. Thus, even with the same amount of heat extracted, the temperature of the heat transfer medium 12 at the outlet 132 of the geothermal heat exchanger 13 tends to decrease less when the thermal conductivity of the soil 2 is high, and decreases more easily when the thermal conductivity of the soil 2 is low.
[0096] Therefore, in the refrigeration cycle device 1 according to this embodiment, the thermal conductivity of the soil 2 at the installation site may be obtained in advance, and if it is predicted that the thermal conductivity of the soil 2 will have a significant influence on the temperature of the heat transfer medium 12, the temperature of the heat transfer medium 12 at the outlet 132 of the ground heat exchanger 13 may be corrected to create at least one of the tables shown in Table 1 and Table 2 above. This improves the accuracy of the criteria for determining whether or not to operate the air heat source unit 14. As a result, the refrigeration cycle device 1 can suppress a decrease in comfort even when the amount of heat extracted from the soil 2 decreases.
[0097] As described above, the refrigeration cycle device 1 comprises air conditioning units 11a and 11b, a heat transfer medium 12 supplied to the air conditioning units 11a and 11b, a geothermal heat exchanger 13 that exchanges heat between the heat transfer medium 12 and the soil 2, an air heat source unit 14 that exchanges heat between the heat transfer medium 12 and the outside air, and a control device 15 that controls the air conditioning units 11a and 11b and the air heat source unit 14. The control device 15 includes a capacity acquisition unit 151 that acquires the required capacity which is the capacity necessary for the air conditioning units 11a and 11b to perform air conditioning operation, a heat extraction limit acquisition unit 152 that acquires the heat extraction limit which is the upper limit of the amount of heat that the geothermal heat exchanger 13 can extract from the soil 2, and an operation determination unit 153 that compares the required capacity and the heat extraction limit and determines whether or not to operate the air heat source unit 14.
[0098] A refrigeration cycle device 1 having such a configuration can suppress a decrease in comfort even when the amount of heat extracted from the ground decreases.
[0099] The present invention is not limited to the above embodiment and can be modified in various ways. In the above embodiment, the capacity acquisition unit 151 acquires the required capacity based on the number of air conditioning units, capacity information, and indoor load, but the present invention is not limited thereto. For example, if the air conditioning unit has indoor units, the capacity acquisition unit 151 may use the number of indoor units instead of the number of air conditioning units to acquire the required capacity.
[0100] 1 Refrigeration cycle device 2 Soil 10 Heat transfer piping 11a, 11b Air conditioning unit 12 Heat transfer medium 13 Geothermal heat exchanger 14 Air heat source unit 15 Control device 16a, 16b Temperature sensor 17 Circulation pump 18a, 18b Three-way valve 19 Flow control valve 111, 112, 141, 142 Heat exchanger 111a, 141a Heat transfer medium flow path 111b, 141b Refrigerant flow path 113, 143 Compressor 114, 144 Four-way valve 115, 145 Expansion valve 116 Room temperature sensor 131 Inlet 132 Outlet 151 Capacity acquisition unit 152 Heat extraction upper limit acquisition unit 153 Operation determination unit 154 Memory unit
Claims
1. A refrigeration cycle apparatus comprising: an air conditioning unit; a heat transfer medium supplied to the air conditioning unit; a geothermal heat exchanger that exchanges heat between the heat transfer medium and soil; an air heat source unit that exchanges heat between the heat transfer medium and outside air; and a control device that controls the air conditioning unit and the air heat source unit, wherein the control device comprises: a capacity acquisition unit that acquires the required capacity which is the capacity necessary for the air conditioning unit to perform air conditioning operation; a heat extraction limit acquisition unit that acquires the heat extraction limit which is the upper limit of the amount of heat that the geothermal heat exchanger can extract from the soil; and an operation determination unit that compares the required capacity and the heat extraction limit to determine whether or not to operate the air heat source unit.
2. The refrigeration cycle apparatus according to claim 1, wherein the heat extraction upper limit acquisition unit acquires a value predetermined by testing as the heat extraction upper limit amount.
3. The refrigeration cycle apparatus according to claim 1, wherein the heat extraction limit acquisition unit acquires the heat extraction limit amount based on past operating data.
4. The refrigeration cycle apparatus according to claim 1, wherein the capacity acquisition unit acquires the required capacity based on the number and capacity information of the air conditioning units and the indoor load, which is the load during the air conditioning operation.
5. The refrigeration cycle apparatus according to claim 1, wherein the control device determines the timing for operating the air heat source unit based on the temperature of the heat medium flowing out of the ground heat exchanger, the amount of heat extracted by the ground heat exchanger from the soil, and the preliminary operation of the air heat source unit.
6. A refrigeration cycle apparatus according to any one of claims 1 to 5, comprising a plurality of the air conditioning units, wherein the plurality of air conditioning units are connected in parallel in the direction of flow of the heat transfer medium.