JPWO2018225193A1 - Hot water supply system - Google Patents

Abstract

In the hot water supply system, a heating unit that heats the primary heat medium and a cascade heat exchanger that exchanges heat between the primary heat medium and the secondary heat medium are connected by a primary pipe, and the primary heat medium circulates. A secondary-side circulation circuit in which a primary-side circulation circuit, a cascade heat exchanger, and a tank that stores a secondary-side heat medium are connected by a secondary-side pipe, and a secondary-side heat medium circulates; A secondary outlet temperature sensor that detects a secondary outlet temperature of the secondary heat medium flowing out from the secondary outlet temperature sensor, and a secondary outlet temperature detected by the secondary outlet temperature sensor is set to the secondary target temperature. A control unit having a flow rate control unit for controlling the primary circulation flow rate of the primary heat medium and the secondary circulation flow rate of the secondary heat medium.

Description

  In the present invention, the primary heat medium flowing in the primary circulation circuit and the secondary heat medium flowing in the secondary circulation circuit are heat-exchanged by the cascade heat exchanger, and the heated secondary heat medium is supplied. The present invention relates to a hot water supply system.

  Conventionally, as a hot water supply system, a heat pump water heater that generates hot water using a heat pump is known. A hot water supply system using a heat pump water heater has, for example, a heat pump circuit, a primary circulation circuit, and a secondary circulation circuit. The heat pump circuit is provided in the heat source unit, and a hot water storage tank is connected to the secondary side circulation circuit. The primary circulation circuit is connected between the heat pump circuit and the secondary circulation circuit via a cascade heat exchanger. In the hot water supply system, water flowing in the secondary circulation circuit is heated by the heat supplied from the heat source unit, and the heated water is stored in a hot water storage tank. In the hot water supply system, the water flowing directly into the secondary circulation circuit is not heated by the heat supplied from the heat pump circuit, but is heated through the primary circulation circuit. For this reason, it is possible to use well water with high hardness and low cost without being affected by water quality limitation and pressure limitation in the heat pump circuit. However, in order to control the outlet temperature of the secondary circuit, the amount of heat medium flowing into the primary circuit, the temperature of the heat medium flowing into the cascade heat exchanger, and the amount of water flowing through the secondary circuit are required. In addition, it is necessary to control the temperature of the hot water supplied to the supply target.

  As a hot water supply system that performs heating control of a secondary circulation circuit, Patent Document 1 discloses a primary outlet water temperature at which water flows into a cascade heat exchanger in a primary circulation circuit, and a water supply system in a secondary circulation circuit. There is disclosed a hot water supply system that controls the flow rate of water in a secondary circulation circuit so that the temperature difference between the secondary side hot water temperature flowing out of the cascade heat exchanger and the secondary side hot water temperature becomes constant. Also in Patent Document 2, similarly to Patent Document 1, the flow rate of water in the secondary-side circulation circuit is controlled such that the temperature difference between the primary-side tapping temperature and the secondary-side tapping temperature becomes a constant temperature difference. A hot water supply system is disclosed. Patent Document 2 detects an abnormality when the temperature difference between the primary side tapping temperature and the secondary side tapping temperature is large. Further, Patent Literature 3 discloses a hot water supply apparatus that takes out hot water of a hot water storage tank preferentially from a medium-temperature hot water supply passage connected to an intermediate portion of the hot water storage tank and uses the hot water for hot water supply.

JP-A-2006-75425 JP 2010-65852 A JP 2005-172324 A

  As described above, in the conventional hot water supply systems such as Patent Literature 1 and Patent Literature 2, in the control of the secondary tapping temperature, the temperature difference between the primary tapping temperature and the secondary tapping temperature becomes a constant temperature difference. In addition, the flow rate of water in the secondary circuit is controlled. However, in Patent Literature 1 and Patent Literature 2, the primary circulation circuit and the secondary circulation circuit are separately controlled, and the flow rate of water in the primary circulation circuit and the flow rate of water in the secondary circulation circuit are different. different. For this reason, the heat exchange efficiency in the cascade heat exchanger is poor. Further, in Patent Literature 1 and Patent Literature 2, there is a possibility that the temperature of hot water discharged to the hot water storage tank does not reach the target temperature. In Patent Document 3, there is no circuit corresponding to the primary side circulation circuit. For this reason, controlling the primary side tapping temperature and the secondary side tapping temperature is not considered.

  The present invention has been made in order to solve the above-described problems, and provides a hot water supply system that improves heat exchange efficiency in a cascade heat exchanger.

  In the hot water supply system according to the present invention, the heating unit that heats the primary heat medium, and a cascade heat exchanger that exchanges heat between the primary heat medium and the secondary heat medium are connected by a primary pipe, and the primary heat A primary-side circulation circuit in which the medium circulates, a cascade heat exchanger, and a tank that stores the secondary-side heat medium are connected by a secondary-side pipe, and a secondary-side circulation circuit in which the secondary-side heat medium circulates, A secondary outlet temperature sensor that detects the secondary outlet temperature of the secondary heat medium flowing out of the cascade heat exchanger, and a secondary outlet temperature detected by the secondary outlet temperature sensor is a secondary target temperature. A controller having flow control means for controlling the primary circulation flow rate of the primary heat medium and the secondary circulation flow rate of the secondary heat medium so as to reach a temperature.

  According to the present invention, the flow control means controls the primary circulation flow and the secondary circulation flow. For this reason, in the cascade heat exchanger, the primary heat medium and the secondary heat medium flow without excess and deficiency. Therefore, the heat exchange efficiency in the cascade heat exchanger can be improved.

1 is a circuit diagram showing a hot water supply system 1 according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a control unit 40 of the hot water supply system 1 according to Embodiment 1 of the present invention. 5 is a graph showing the relationship between the secondary outlet temperature and the amount of scale attached in Embodiment 1 of the present invention. 1 is a circuit diagram showing a hot water supply system 1 according to Embodiment 1 of the present invention. 4 is a flowchart illustrating an operation of a flow rate control according to the first embodiment of the present invention. 5 is a flowchart illustrating an abnormal stop operation according to the first embodiment of the present invention. 5 is a flowchart illustrating an abnormal stop operation according to the first embodiment of the present invention. It is a circuit diagram showing a hot water supply system 2 according to Embodiment 2 of the present invention. FIG. 9 is a circuit diagram showing a hot water supply system 3 according to Embodiment 3 of the present invention. FIG. 9 is a circuit diagram showing a hot water supply system 4 according to Embodiment 4 of the present invention. It is a circuit diagram showing a hot water supply system 5 according to Embodiment 5 of the present invention. It is a circuit diagram showing a hot water supply system 6 according to Embodiment 6 of the present invention. It is a circuit diagram showing a hot water supply system 7 according to Embodiment 7 of the present invention. It is a circuit diagram showing a hot water supply system 8 according to Embodiment 8 of the present invention. It is a circuit diagram showing a hot water supply system 9 according to Embodiment 9 of the present invention.

Embodiment 1 FIG.
Hereinafter, embodiments of a hot water supply system according to the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a hot water supply system 1 according to Embodiment 1 of the present invention. The hot water supply system 1 will be described based on FIG. As shown in FIG. 1, the hot water supply system 1 includes a heat source unit 11, a cascade heat exchanger 13, a tank 22, and a control unit 40. Further, the heat source unit 11 is provided with a heat pump circuit 11 a and a part of the primary side circulation circuit 14, and the primary side circulation circuit 14 and the secondary side circulation circuit 15 are connected by the cascade heat exchanger 13. Have been. In the hot water supply system 1, the heat generated by the heat pump circuit 11a is sent to the secondary heat medium flowing to the secondary circulation circuit 15 via the primary circulation circuit 14, and the secondary heat medium is heated.

(Heat pump circuit 11a)
In the heat pump circuit 11a, the compressor 61, the heating unit 12, the expansion unit 62, and the heat source heat exchanger 63 are connected by a heat pump pipe, and the refrigerant circulates. The compressor 61 sucks the refrigerant in a low-temperature and low-pressure state, compresses the sucked refrigerant into a high-temperature and high-pressure state refrigerant, and discharges the refrigerant. The heating unit 12 is a refrigerant heat medium heat exchanger that exchanges heat between the refrigerant and the primary heat medium. The heating unit 12 heat-exchanges the refrigerant and the primary heat medium to heat the primary heat medium. The expansion section 62 is a pressure reducing valve or an expansion valve that decompresses and expands the refrigerant. The expansion section 62 is, for example, an electronic expansion valve whose opening is adjusted. The heat source heat exchanger 63 exchanges heat between the refrigerant and the heat medium. As the refrigerant, for example, a CO ₂ refrigerant is used. In the first embodiment, the heating of the primary-side heat medium by the heating unit 12 is performed using a heat pump. However, as long as it supplies heat to the outside, regardless of its configuration, for example, a heater or the like may be used. It may be performed using.

(Primary circuit 14)
In the primary circulation circuit 14, the primary pump 16, the primary flow control valve 18, the heating unit 12, and the cascade heat exchanger 13 are connected by the primary pipe 14c, and the primary heat medium circulates. The primary circulation circuit 14 is connected to the heat pump circuit 11a via the heating unit 12. Here, the primary side pipe 14c has a primary side outlet pipe 14a and a primary side inlet pipe 14b. The primary-side outlet pipe 14a connects the downstream side of the heating unit 12 and the upstream side of the cascade heat exchanger 13. The primary inlet pipe 14 b connects the downstream side of the cascade heat exchanger 13 and the upstream side of the heating unit 12.

  The primary side pump 16 conveys a primary side heat medium. The primary flow rate adjusting valve 18 is a valve that adjusts the primary circulation flow rate V1 of the primary heat medium, and is, for example, an electronic expansion valve whose opening degree is adjusted. The cascade heat exchanger 13 exchanges heat between the primary heat medium and the secondary heat medium. The cascade heat exchanger 13 exchanges heat between the primary heat medium and the secondary heat medium to heat the secondary heat medium. As the primary heat medium, for example, water or brine is used. In the case where the primary heat medium is water, tap water may be used, or water with high hardness such as well water may be used.

  The primary circulation circuit 14 includes a primary flow sensor 20, a primary inlet temperature sensor 31, and a primary outlet temperature sensor 32. The primary flow sensor 20 detects a primary circulation flow rate V1 of the primary heat medium. The primary-side inlet temperature sensor 31 detects a primary-side inlet temperature T1low of the primary-side heat medium flowing out of the cascade heat exchanger 13 and flowing into the heating unit 12. The primary-side outlet temperature sensor 32 detects a primary-side outlet temperature T1 of the primary-side heat medium flowing out of the heating unit 12 and flowing into the cascade heat exchanger 13. In addition, the primary side outlet temperature T1 is also called primary side hot water temperature.

(Secondary circuit 15)
The secondary-side circulation circuit 15 is a circuit in which the secondary-side pump 17, the secondary-side flow control valve 19, the cascade heat exchanger 13, and the tank 22 are connected by the secondary-side pipe 15d, and the secondary-side heat medium circulates. is there. The secondary circuit 15 is connected to the primary circuit 14 via the cascade heat exchanger 13. Here, the secondary pipe 15d has a secondary outlet pipe 15a and a secondary inlet pipe 15b. The secondary outlet pipe 15 a connects the downstream side of the cascade heat exchanger 13 and the upstream side of the tank 22. The secondary inlet pipe 15b connects the downstream side of the tank 22 and the upstream side of the cascade heat exchanger 13. The secondary pump 17 conveys a secondary heat medium. The secondary flow rate adjusting valve 19 is a valve that adjusts the secondary circulation flow rate V2 of the secondary heat medium, and is, for example, an electronic expansion valve whose opening is adjusted. The tank 22 is a container that stores the secondary heat medium. As the secondary heat medium, for example, water is used.

  The tank 22 is provided with an upper inlet 71, a lower outlet 72, an upper supply port 73, a supply port 74, and an upper return port 75. The upper inlet 71 is an opening provided in the upper part of the tank 22 and through which the secondary heat medium flowing out of the cascade heat exchanger 13 flows. The lower outlet 72 is an opening provided at a lower portion of the tank 22 and through which the secondary-side heat medium flows out of the tank 22. The upper supply port 73 is an opening that is connected to the supply pipe 51 above the tank 22 and through which the secondary-side heat medium flows out to the supply target through the supply pipe 51. The supply port 74 is an opening that is connected to the supply pipe 52 in the upper part of the tank 22 and is supplied with a secondary-side heat medium from a supply source. The upper return port 75 is an opening through which the secondary heat medium supplied to the supply target is returned and flows in from the return pipe 53.

  Inside the tank 22, a high-temperature secondary-side heat medium is stored in the upper part, and a low-temperature secondary-side heat medium is stored in the lower part. That is, the inside of the tank 22 has a temperature stratification in which the upper portion has a high temperature, the lower portion has a low temperature, and the middle portion has a medium temperature. When a supply load occurs in the supply target of the tank 22, the high-temperature secondary-side heat medium flows out from the upper supply port 73 and is supplied to the supply target. When the high-temperature secondary-side heat medium is supplied to the supply target, the low-temperature secondary-side heat medium is supplied into the tank 22 from the supply source through the supply port 74.

  The secondary-side circulation circuit 15 is provided with a secondary-side flow sensor 21 and a secondary-side outlet temperature sensor 33. The secondary flow sensor 21 detects a secondary circulation flow rate V2 of the secondary heat medium. The secondary outlet temperature sensor 33 detects a secondary outlet temperature T2 of the secondary heat medium flowing out of the cascade heat exchanger 13 and flowing into the tank 22. In addition, the secondary side outlet temperature T2 is also called a secondary side hot water temperature.

  Here, the compressor 61, the heating unit 12, the expansion unit 62, the heat source heat exchanger 63, the primary pump 16, the primary flow control valve 18, the primary flow sensor 20, the primary inlet temperature sensor 31, the primary outlet temperature. The sensor 32 and the control unit 40 are housed in the heat source unit 11. The heat source unit 11 is a unit called a heat pump water heater. Here, in the primary side circulation circuit 14, since the primary side heat medium which is not the refrigerant circulates, clogging of the scale in the heat source unit 11 is suppressed. For this reason, water of high quality such as well water can be used. The hot water supply system 1 includes a notification unit 85 that notifies an abnormality (see FIG. 2). The notification unit 85 is configured by, for example, a display device or a speaker.

(Hot water supply operation)
Next, the hot water supply operation will be described. First, the flow of the refrigerant in the heat pump circuit 11a will be described. In the heat pump circuit 11a, the refrigerant drawn into the compressor 61 is compressed by the compressor 61 and discharged in a high-temperature, high-pressure gas state. The high-temperature and high-pressure refrigerant discharged from the compressor 61 flows into the heating unit 12, where the refrigerant exchanges heat with the primary heat medium and is cooled. At this time, the low-temperature primary-side heat medium is heated. The cooled refrigerant flows into the expansion section 62 and is expanded and decompressed in the expansion section 62. Then, the expanded and decompressed refrigerant flows into the heat source heat exchanger 63, where the refrigerant exchanges heat with the heat medium and is heated. The heated low-temperature low-pressure refrigerant is sucked into the compressor 61.

  Next, the flow of the primary heat medium in the primary circulation circuit 14 will be described. In the primary side circulation circuit 14, the primary side heat medium sucked into the primary side pump 16 is conveyed toward the heating unit 12. The transported primary-side heat medium flows into the heating unit 12 through the primary-side flow control valve 18, and is heated by exchanging heat with the refrigerant in the heating unit 12. The heated primary-side heat medium flows into the cascade heat exchanger 13, where the heat is exchanged with the secondary-side heat medium and cooled. At this time, the low-temperature secondary heat medium is heated. Then, the cooled primary heat medium is sucked into the primary pump 16.

  Next, the flow of the secondary heat medium in the secondary circulation circuit 15 will be described. In the secondary side circulation circuit 15, the secondary side heat medium sucked into the secondary side pump 17 is conveyed toward the cascade heat exchanger 13. The transported secondary-side heat medium flows into the cascade heat exchanger 13 through the secondary-side flow control valve 19, where the cascade heat exchanger 13 exchanges heat with the primary-side heat medium and is heated. The heated secondary-side heat medium flows into the upper inlet 71 of the tank 22. Thereby, a high-temperature secondary-side heat medium is stored in the upper part of the tank 22.

(Control unit 40)
Next, the control unit 40 will be described. The controller 40 controls the primary circulation flow rate V1 of the primary heat medium detected by the primary flow rate sensor 20, the secondary circulation flow rate V2 of the secondary heat medium detected by the secondary flow sensor 21, Based on the primary inlet temperature T1low detected by the inlet temperature sensor 31, the primary outlet temperature T1 detected by the primary outlet temperature sensor 32, and the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 33. The operation of the hot water supply system 1 is controlled.

  FIG. 2 is a block diagram showing control unit 40 of hot water supply system 1 according to Embodiment 1 of the present invention. As shown in FIG. 2, the control unit 40 includes a target setting unit 90, a first determination unit 82, a second determination unit 83, a flow control unit 81, an abnormality determination unit 86, a map creation unit 87, and a flow determination unit 88. And abnormal stop means 89.

(Target setting means 90)
The target setting means 90 sets a primary-side target temperature T1m, which is a target value of the primary-side outlet temperature T1, and a secondary-side target temperature T2m, which is a target value of the secondary-side outlet temperature T2. Further, the target setting means 90 sets a primary target flow rate V1m, which is a target value of the primary circulation flow rate V1, and a secondary target flow rate V2m, which is a target value of the secondary circulation flow rate V2.

(First judgment means 82, second judgment means 83)
The first determination unit 82 determines whether the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 33 is lower than the secondary target temperature T2m. The second determination unit 83 determines whether the primary target temperature T1m set as the target value of the primary outlet temperature T1 of the primary heat medium flowing out of the heating unit 12 is the target upper limit temperature T1mmmax. The second determination unit 83 determines whether the primary circulation flow rate V1 and the secondary circulation flow rate V2 are the same, or whether the primary circulation flow rate V1 is larger than the secondary circulation flow rate V2. Note that the target upper limit temperature T1mmmax is, for example, 90 [° C.]. Further, a secondary target upper limit value T2mmax of the secondary target temperature T2m may be determined. In this case, the secondary target upper limit value T2mmmax is obtained, for example, from the following equation (1).

[Equation 1]
T2mmmax = T1mmmax-β (1)

  Here, β [° C.] satisfies 2 <β <20, and the initial value is set to, for example, 5 [° C.].

(Flow control means 81)
The flow rate control means 81 controls the primary-side circulating flow rate V1 and the secondary-side heat medium so that the secondary-side outlet temperature T2 detected by the secondary-side outlet temperature sensor 33 becomes the secondary-side target temperature T2m. The secondary circulation flow rate V2 of the heat medium is controlled. The flow rate control means 81 may control the primary circulation flow rate V1 of the primary heat medium by the primary pump 16 or the primary flow control valve 18. Here, the flow control means 81 controls the primary circulation flow V1 of the primary heat medium detected by the primary flow sensor 20 so as to be the primary target flow V1m. Further, the flow rate control means 81 may control the secondary-side circulation flow rate V2 of the secondary-side heat medium with the secondary-side pump 17 or the secondary-side flow rate adjusting valve 19. Here, the flow control means 81 controls the primary circulation flow rate V1 of the secondary heat medium detected by the secondary flow sensor 21 so as to be the secondary target flow rate V2m.

(Abnormality determination means 86)
The abnormality determining means 86 determines an abnormality. The abnormality determination unit 86 determines whether the difference between the secondary outlet temperature T2 and the secondary target temperature T2m exceeds a secondary temperature difference threshold. The secondary-side temperature difference threshold is set as a value at which the secondary-side outlet temperature T2 and the secondary-side target temperature T2m are so far apart that inspection or the like is necessary. Then, the notification unit 85 determines the difference between the secondary-side outlet temperature T2 detected by the secondary-side outlet temperature sensor 33 and the secondary-side target temperature T2m by the abnormality determination unit 86 as a secondary-side temperature difference threshold. If it is determined that it has exceeded, an abnormality is notified.

  The abnormality determining means 86 determines that the difference between the primary outlet temperature T1 detected by the primary outlet temperature sensor 32 and the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 33 is a temperature difference threshold. Is determined.

(Map creation means 87)
The map creating means 87 creates a primary flow map indicating the flow rate of the primary heat medium in the primary circulation circuit 14 and a secondary flow map indicating the flow rate of the secondary heat medium in the secondary circulation circuit 15. I do. In the primary circulation circuit 14, the map creator 87 performs the primary circulation of the primary heat medium detected by the primary flow sensor 20 for each of the opening of the primary pump 16 and the opening of the primary flow regulating valve 18. The flow rate V1 is acquired, and a flow rate map of the primary side circulation circuit 14 is created. That is, the primary flow rate map indicates, for example, the flow rate of the primary heat medium for each of the opening degree of the primary pump 16 and the opening degree of the primary flow control valve 18. Further, in the secondary circulation circuit 15, the map creating means 87 outputs the secondary flow rate detected by the secondary flow rate sensor 21 for each of the opening degree of the secondary pump 17 and the opening degree of the secondary flow rate regulating valve 19. The secondary circulation flow rate V2 of the side heat medium is acquired, and a flow map of the secondary circulation circuit 15 is created. That is, the secondary flow map indicates the flow rate of the secondary heat medium for each opening of the secondary pump 17 and the opening of the secondary flow control valve 19, for example.

(Flow rate determining means 88)
The flow rate determining means 88 determines whether the flow rate value of the primary flow rate map created by the map creating means 87 and the amount of the primary heat medium actually flowing exceed the primary flow rate difference threshold, or It is determined whether the flow rate value of the secondary flow rate map and the flow rate of the secondary heat medium that have actually flowed have exceeded the secondary flow rate difference threshold. Further, the flow rate determining means 88 determines whether the temperature change rate of the primary outlet temperature T1 and the secondary outlet temperature T2 is equal to or lower than the speed threshold. Here, the temperature change speed is a value obtained by dividing the temperature change amount ΔT [° C.] by the time [min]. When the temperature change rate exceeds the speed threshold, the flow rate determining means 88 determines that the amount of the primary heat medium flowing and the amount of the secondary heat medium flow are the specified amounts.

  On the other hand, when the temperature change rate is equal to or less than the speed threshold, the flow rate determining unit 88 determines that the amount of the primary heat medium flowing and the amount of the secondary heat medium flowing are insufficient. Then, the flow rate determination means 88 further determines whether the difference between the flow rate value of the primary flow rate map created by the map creation means 87 and the amount of the primary heat medium actually flowing exceeds the primary flow rate difference threshold, or It is determined whether or not the difference between the flow rate value of the secondary flow rate map created by the map creation means 87 and the actual flow amount of the secondary heat medium exceeds the secondary flow rate difference threshold.

(Abnormal stop means 89)
The abnormality stopping unit 89 stops the operation of the heat source unit 11 when the abnormality determining unit 86 determines that the difference between the primary outlet temperature T1 and the secondary outlet temperature T2 exceeds the temperature difference threshold. When the difference between the primary outlet temperature T1 and the secondary outlet temperature T2 is large, it is determined that the amount of the primary heat medium flowing and the amount of the secondary heat medium flowing are insufficient. In the primary-side circulation circuit 14 or the secondary-side circulation circuit 15, if a scale or foreign matter is clogged, the primary-side heat medium or the secondary-side heat medium becomes difficult to flow. Therefore, the abnormal stop unit 89 stops the operation of the heat source unit 11.

  In addition, the abnormal stop means 89 determines whether the difference between the flow rate value of the primary flow rate map and the actual flow rate of the primary heat medium has exceeded the primary flow rate difference threshold, or If it is determined that the difference between the flow value on the map and the amount of the secondary heat medium that actually flows exceeds the secondary flow difference threshold, the operation of the heat source unit 11 is stopped. When the flow rate value of the primary flow rate map and the actual flow rate of the primary heat medium exceed the primary flow rate difference threshold, it is determined that the flow rate of the primary heat medium is insufficient. When the flow rate value of the secondary flow rate map and the actual flow rate of the secondary heat medium exceed the secondary flow rate difference threshold, it is determined that the flow rate of the secondary heat medium is insufficient. .

  In the primary-side circulation circuit 14 or the secondary-side circulation circuit 15, if a scale or foreign matter is clogged, the primary-side heat medium or the secondary-side heat medium becomes difficult to flow. Therefore, the abnormal stop unit 89 stops the operation of the heat source unit 11. As described above, in the hot water supply system 1, in the primary side circulation circuit 14 or the secondary side circulation circuit 15, the flow rate of the primary side heat medium or the secondary side heat medium decreased due to clogging of scale, clogging of foreign matter, freezing, or the like. Can be detected.

FIG. 3 is a graph showing the relationship between the secondary outlet temperature and the amount of scale adhered in the first embodiment of the present invention. In FIG. 3, the horizontal axis is the secondary outlet temperature T2 [° C.], and the vertical axis is the calcium scale adhesion amount [μg / cm ² / hr]. In the first embodiment, the scale of calcium will be exemplified. The target setting means 90 sets the secondary target temperature T2m to a temperature at which the amount of scale deposited on the secondary pipe 15d is less than the threshold for the amount of deposition. As shown in FIG. 3, the smaller the secondary outlet temperature T2, the smaller the scale adhesion amount. Therefore, the target setting means 90 suppresses the secondary target temperature T2m to a predetermined temperature or less. Thereby, scale clogging in the secondary side circulation circuit 15 can be suppressed.

(Detailed description of the flow control means 81)
FIG. 4 is a circuit diagram showing hot water supply system 1 according to Embodiment 1 of the present invention. Next, the control will be described in detail. In this control, in order to improve the heat exchange efficiency in the cascade heat exchanger 13, control is performed so that the primary circulation flow rate V1 and the secondary circulation flow rate V2 are the same. In the following description, as shown in FIG. 4, the primary outlet temperature T1, the secondary outlet temperature T2, the primary target temperature T1m, the secondary target temperature T2m, the primary circulation flow rate V1, and the secondary circulation flow rate V2 , A primary target flow rate V1m and a secondary target flow rate V2m.

  FIG. 5 is a flowchart showing the flow control operation according to the first embodiment of the present invention. As shown in FIG. 5, the target setting means 90 compares the primary side circulation flow rate V1 and the secondary side circulation flow rate V2 during the hot water supply operation (step ST1), and the secondary side circulation flow rate V2 is V1 × α1 ≦ If V2m ≦ V1 × α2, the primary circulation flow rate V1 and the secondary circulation flow rate V2 are regarded as the same flow rate. In the case of V1 × α1> V2m or V2m> V1 × α2, it is determined that the primary circulation flow V1 and the secondary circulation flow V2 are different. If it is determined that the flow rates are different, the secondary flow map is corrected by multiplying the flow rate of the secondary flow map of the secondary circulation circuit 15 by the value of α3 (correction A, step ST2). ). Further, the secondary-side target flow rate V2m is corrected to V2m = V1 (correction B, step ST3). In this way, control is performed so that the primary side circulation flow rate V1 and the secondary side circulation flow rate V2 are the same. That is, the mode setting means of the control unit 40 sets the same flow control mode. Note that ΔT1, α1, α2, and α3 are predetermined values.

  After the primary circulation flow rate V1 and the secondary circulation flow rate V2 are controlled to be the same, the primary exit temperature T1 is controlled so that the secondary exit temperature T2 becomes the secondary target temperature T2m. You. If the secondary outlet temperature T2 satisfies T2m ≦ T2 ≦ T2m + ΔT2 (step ST4) and the primary outlet temperature T1 satisfies T1m ≦ T1 ≦ T1m + ΔT1 (step ST5), no correction is performed. On the other hand, if the secondary outlet temperature T2 satisfies T2m ≦ T2 ≦ T2m + ΔT2, but the primary outlet temperature T1 is T1m> T1 or T1> T1m + ΔT1 and deviates from the primary target temperature T1m, the primary target temperature T1m. Is corrected to T1m + β1 (correction C, step ST6). If the condition of step ST4 is not satisfied, T2 and T2m are compared (step ST7). When the secondary outlet temperature T2 is T2m> T2, the primary outlet temperature T1 is corrected to T1m + β2 (correction D, step ST8). Further, when the secondary outlet temperature T2 is T2> T2m + ΔT2, the primary target temperature T1m is corrected to T1m + β3 (correction E, step ST9). Note that ΔT2, β1, β2, and β3 are predetermined values.

  By the control shown in FIG. 5, the primary side circulation flow rate V1 and the secondary side circulation flow rate V2 become the same flow rate. Further, the primary-side outlet temperature T1 and the secondary-side outlet temperature T2 are controlled so as to be the target temperatures, respectively. As described above, the primary-side circulation flow rate V1 and the secondary-side circulation flow rate V2 are controlled to be the same, and the heat exchange efficiency in the cascade heat exchanger 13 is improved.

  The primary side target temperature T1m and the secondary side target temperature T2m may be obtained not only by addition and subtraction but also by multiplication and division. Here, the rate at which the secondary flow rate is reduced is determined by a calculation formula. First, the unknown secondary-side inlet temperature T2low is determined. From the primary circulation flow rate V1, the secondary circulation flow rate V2, the primary inlet temperature T1low, the primary outlet temperature T1, the secondary outlet temperature T2, and the secondary inlet temperature T2low, the following heat exchange equation (2) is obtained. To establish.

[Equation 2]
V1 × (T1-T1low) = V2 × (T2-T2low) (2)

  The unknown secondary inlet temperature T2low is obtained from the following equation (3) obtained by converting the above equation (2).

[Equation 3]
T2low = (V2 × T2-V1 × (T1-T1low)) / V2 (3)

  After the secondary inlet temperature T2low is obtained from the above equation (3), a secondary target flow rate V2m is obtained. Here, the following equation (4) for heat exchange is established.

[Equation 4]
V1 × (T1−T1low) = V2m × (T2m−T2low) (4)

  The secondary target flow rate V2m is obtained from the following equation (5) obtained by converting the above equation (4).

[Equation 5]
V2m = (V1 × (T1−T1low)) / (T2m−T2low) (5)

  The lower limit of the secondary circulation flow rate V2 is, for example, 3.3 [L / min]. However, the initial flow rate at startup of the hot water supply system 1 is assumed to be lower than the lower limit value, and the lower limit value is applied, for example, when returning from the defrosting operation.

(Abnormal stop operation)
FIG. 6 is a flowchart showing the operation of the abnormal stop according to the first embodiment of the present invention. Next, the operation of the abnormal stop will be described. As shown in FIG. 6, when the operation of the hot water supply system 1 is started, the target setting means 90 sets the primary target temperature T1m or the secondary target flow in the same flow control mode in any of the patterns in Table 1. V2m is changed (step ST11). Then, the abnormality determining means 86 determines whether the difference between the primary outlet temperature T1 and the secondary outlet temperature T2 exceeds the temperature difference threshold (step ST12). When the difference between the primary outlet temperature T1 and the secondary outlet temperature T2 is equal to or less than the temperature difference threshold value (No in step ST12), the process returns to step ST11. On the other hand, when the difference between the primary-side outlet temperature T1 and the secondary-side outlet temperature T2 exceeds the temperature difference threshold (Yes in step ST12), the abnormal stop means 89 stops the heat source unit 11.

  FIG. 7 is a flowchart showing the operation of the abnormal stop according to Embodiment 1 of the present invention. As shown in FIG. 7, at the time of the test operation, the map creation means 87 uses the primary-side flow map indicating the amount of the primary-side heat medium flowing in the primary-side circulation circuit 14 and the secondary-side heat medium in the secondary-side circulation circuit 15. And a secondary-side flow map indicating the flow amount is created (step ST21). Then, the test operation of hot water supply system 1 ends (step ST22). When the operation of the hot water supply system 1 is started (step ST23), the flow rate determining means 88 determines whether the temperature change rates of the primary-side outlet temperature T1 and the secondary-side outlet temperature T2 are equal to or lower than a speed threshold (step ST23). Step ST24).

  If the temperature change rates of the primary outlet temperature T1 and the secondary outlet temperature T2 are greater than the speed threshold (No in step ST24), the process returns to step ST24. On the other hand, when the temperature change rates of the primary-side outlet temperature T1 and the secondary-side outlet temperature T2 are equal to or lower than the speed threshold value (Yes in step ST24), the flow rate determining unit 88 creates the primary-side flow map created by the map creating unit 87. Or the flow rate of the primary heat medium actually exceeds the primary flow rate difference threshold, or the flow rate value and the secondary heat medium of the secondary flow map created by the map creation means 87 are Is determined to have exceeded the secondary flow rate difference threshold (step ST25). When the condition of step ST25 is not satisfied (No in step ST25), the process returns to step ST24. On the other hand, when the condition of step ST25 is satisfied (Yes in step ST25), the heat source unit 11 is stopped by the abnormal stop unit 89.

  According to the first embodiment, the flow control means 81 controls the primary circulation flow V1 and the secondary circulation flow V2. For this reason, in the cascade heat exchanger 13, the primary side heat medium and the secondary side heat medium flow without excess or shortage. Therefore, while improving the heat exchange efficiency in the cascade heat exchanger 13, the secondary outlet temperature T2 of the secondary heat medium flowing out of the cascade heat exchanger 13 in the secondary circulation circuit 15 is reduced to the secondary target temperature T2m. It can be.

  Further, the control unit 40 includes a mode setting unit 80 for setting the same circulation rate control mode in which the primary circulation flow rate V1 and the secondary circulation flow rate V2 are the same. , The primary side circulation flow rate V1 and the secondary side circulation flow rate V2 are controlled to be the same. Thereby, the heat exchange efficiency in the cascade heat exchanger 13 is improved.

  It further includes a primary outlet temperature sensor 32 for detecting a primary outlet temperature T1 of the primary heat medium flowing out of the heating unit 12, and the flow control unit 81 has a secondary outlet temperature T2, a primary circulation flow rate V1, The primary-side target temperature T1m or the secondary-side target flow rate V2m is controlled based on the secondary-side circulation flow rate V2 and the primary-side outlet temperature T1 detected by the primary-side outlet temperature sensor 32. Thus, the flow rate control can be performed such that the primary circulation flow rate V1 and the secondary circulation flow rate V2 become the same.

  Then, the controller 40 determines whether the difference between the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 33 and the secondary target temperature T2m exceeds the secondary temperature difference threshold. A notifying unit for notifying an abnormality when the abnormality determining unit 86 determines that the difference between the secondary outlet temperature T2 and the secondary target temperature T2m exceeds the secondary temperature threshold; 85 is further provided. When the secondary outlet temperature T2 and the secondary target temperature T2m are so far apart that an inspection or the like is necessary, the abnormality or the like is notified, so that an operator or the like can immediately perform an inspection or the like.

  The control unit 40 further includes a heat source unit 11 having a heating unit 12, and the control unit 40 further includes an abnormal stop unit 89 that stops operation of the heat source unit 11 when an abnormality occurs. The control unit 40 further includes a primary outlet temperature sensor 32 that detects a primary outlet temperature T1 of the primary heat medium flowing out of the heating unit 12, and the control unit 40 controls the primary outlet temperature detected by the primary outlet temperature sensor 32. The apparatus further includes abnormality determination means 86 for determining whether the difference between T1 and the secondary-side exit temperature T2 detected by the secondary-side exit temperature sensor 33 has exceeded a temperature difference threshold. When the determining unit 86 determines that the difference between the primary outlet temperature T1 and the secondary outlet temperature T2 exceeds the temperature difference threshold, the operation of the heat source unit 11 is stopped. This makes it possible to predict that clogging or freezing due to scale has occurred in the primary side circulation circuit 14 and the secondary side circulation circuit 15 and to perform an inspection or the like.

  Further, the control unit 40 generates a primary flow map indicating the flow rate of the primary heat medium in the primary circulation circuit 14 and a secondary flow map indicating the flow rate of the secondary heat medium in the secondary circulation circuit 15. The map creating means 87 to be created, and whether the difference between the flow rate value of the primary flow rate map created by the map creating means 87 and the amount of the primary heat medium actually flowing exceeds the primary flow rate difference threshold, or Flow rate determining means 88 for determining whether the difference between the flow rate value of the secondary flow rate map created by the means 87 and the actual flow rate of the secondary heat medium exceeds the secondary flow rate difference threshold. Then, the abnormality stopping means 89 determines whether the difference between the flow rate value of the primary flow map and the actual flow rate of the primary heat medium exceeds the primary flow rate difference threshold, or Map flow rate value and secondary heat medium If it is the difference between the amount actually flowing is determined to have exceeded the secondary flow rate difference threshold, stopping the operation of the heat source unit 11. This makes it possible to predict that clogging or freezing due to scale has occurred in the primary side circulation circuit 14 and the secondary side circulation circuit 15 and to perform an inspection or the like.

  The control unit 40 further includes a target setting unit 90 that sets the secondary target temperature T2m to a temperature at which the amount of scale deposited on the secondary pipe 15d is less than the threshold for the amount of deposition. Thereby, clogging of the scale in the secondary side circulation circuit 15 can be suppressed.

  Further, the control unit 40 is provided in the heat source unit 11 and comprehensively controls the operations of the primary side circulation circuit 14 and the secondary side circulation circuit 15. For this reason, since the state of the secondary side circulation circuit 15 can be grasped on the heat source unit 11 side, it is possible to immediately recognize when an abnormality occurs.

Embodiment 2 FIG.
FIG. 8 is a circuit diagram showing a hot water supply system 2 according to Embodiment 2 of the present invention. The second embodiment is different from the first embodiment in that a buffer tank 60 is provided. In the second embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 8, the buffer tank 60 is provided between the downstream side of the cascade heat exchanger 13 and the primary side pump 16 provided in the heat source unit 11 in the primary side circulation circuit 14, and supplies the primary side heat medium. It is a container to store. When the primary outlet temperature T1 on the downstream side of the cascade heat exchanger 13 suddenly changes from a low temperature to a high temperature, the operation state of the heat source unit 11 changes and the high pressure increases, and the refrigerant temperature of the heat pump circuit 11a increases. Then, there is a possibility that an abnormality such as liquid back to the compressor 61 in the heat source unit 11 may occur.

  As described above, the conventional hot water supply system has a problem that the temperature of the primary heat medium entering the heat source unit (input water temperature) changes suddenly. In the second embodiment, by providing the buffer tank 60, even if the primary outlet temperature T1 on the downstream side of the cascade heat exchanger 13 suddenly changes from a low temperature to a high temperature, the primary heat medium entering the heat source unit 11 Can be kept at a low temperature. Thereby, the heat source unit 11 can be protected. The primary circulation circuit 14 is a closed circuit. When the temperature of the primary heat medium rises, the primary heat medium expands, but the expansion of the primary heat medium can be absorbed by the buffer tank 60. .

Embodiment 3 FIG.
FIG. 9 is a circuit diagram showing a hot water supply system 3 according to Embodiment 3 of the present invention. The third embodiment is different from the first embodiment in that a secondary inlet temperature sensor 34 is provided instead of the secondary flow sensor 21. In the third embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 9, the secondary-side circulation circuit 15 is provided with a secondary-side inlet temperature sensor 34. The secondary-side inlet temperature sensor 34 is a sensor that detects the secondary-side inlet temperature T2low of the secondary-side heat medium flowing out of the tank 22 and flowing into the cascade heat exchanger 13.

  The control unit 40 has a flow rate calculating means 91. The flow rate calculating means 91 calculates the secondary side temperature based on the secondary side outlet temperature T2 detected by the secondary side outlet temperature sensor 33 and the secondary side inlet temperature T2low detected by the secondary side inlet temperature sensor 34. The secondary circulation flow rate V2 of the heat medium is determined. More specifically, in addition to the secondary outlet temperature T2 and the secondary inlet temperature T2low, the flow rate calculating means 91 includes a primary inlet temperature T1low detected by the primary inlet temperature sensor 31, a primary outlet temperature sensor A secondary-side circulation flow rate V2 is obtained based on the primary-side outlet temperature T1 detected by the P. 32 and the primary-side circulation flow rate V1 detected by the primary-side flow sensor 20.

  Since the amount of heat Q exchanged in the cascade heat exchanger 13 is equal in the primary circulation circuit 14 and the secondary circulation circuit 15, the heat amount Q is obtained from the following heat exchange equation (6).

[Equation 6]
Q = V1 × (T1-T1low) = V2 × (T2-T2low) (6)

  From the equation (6), the secondary circulation flow rate V2 can be approximately obtained. As described above, in the third embodiment, the secondary-side flow rate V2 can be approximately obtained by providing the secondary-side inlet temperature sensor 34, and thus the secondary-side flow rate sensor 21 is unnecessary. For this reason, cost can be reduced in configuring the secondary side circulation circuit 15. Usually, the same flow control mode is performed, and the primary target temperature T1m and the secondary target temperature T2m are changed so that the primary circulation flow V1 and the secondary circulation flow V2 become the same.

Embodiment 4 FIG.
FIG. 10 is a circuit diagram showing a hot water supply system 4 according to Embodiment 4 of the present invention. The fourth embodiment is different from the first embodiment in that the secondary pump 17 is an inverter pump. In the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  In the fourth embodiment, the flow control unit 81 controls the secondary circulation flow V2 by adjusting the rotation speed of the secondary pump 17 that is an inverter pump. For this reason, as shown in FIG. 10, the secondary flow control valve 19 can be omitted. Therefore, it is possible to reduce costs in configuring the secondary-side circulation circuit 15.

Embodiment 5 FIG.
FIG. 11 is a circuit diagram showing a hot water supply system 5 according to Embodiment 5 of the present invention. The fifth embodiment is different from the first embodiment in that the control unit 40 is divided into a primary control unit 40a and a secondary control unit 40b. In the fifth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 11, the primary control unit 40a is provided in the heat source unit 11, and controls the operation of the primary circulation circuit 14. Further, the secondary side control unit 40b is provided outside the heat source unit 11 and controls the operation of the secondary side circulation circuit 15. Note that the primary side control unit 40a and the secondary side control unit 40b are connected, and the primary side control unit 40a checks the status of the secondary side circulation circuit 15 via the secondary side control unit 40b. Can be. By dividing the control unit 40, more accurate control can be performed.

Embodiment 6 FIG.
FIG. 12 is a circuit diagram showing a hot water supply system 6 according to Embodiment 6 of the present invention. The sixth embodiment differs from the first embodiment in that a tank temperature sensor 35 is provided. In the sixth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 12, the tank temperature sensor 35 is provided above the tank 22 and is a sensor that detects the tank temperature of the secondary-side heat medium stored in the tank 22. Further, the target setting means 90 sets a primary target temperature T1m and a secondary target temperature T2m based on the tank temperature detected by the tank temperature sensor 35. The control unit 40 of the hot water supply system 1 operates the heat source unit 11 when the tank temperature is lower than the predetermined set temperature, and stops the heat source unit 11 when the tank temperature becomes higher than the set temperature. As described above, since the primary target temperature T1m and the secondary target temperature T2m are set based on the tank temperature, the flow control unit 81 controls the primary circulation flow V1 and the secondary circulation flow V2. Above, more precise control can be performed.

Embodiment 7 FIG.
FIG. 13 is a circuit diagram showing a hot water supply system 7 according to Embodiment 7 of the present invention. The seventh embodiment is different from the first embodiment in that the tank 22 is provided with a middle inlet 76. In the seventh embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 13, the tank 22 is provided with a middle inlet 76 in addition to the upper inlet 71. The middle inlet 76 is provided below the upper inlet 71 and is an opening through which the secondary-side heat medium flowing out of the cascade heat exchanger 13 flows. In addition, the primary side circulation circuit 14 is provided with an inflow switching unit 23. The inflow switching unit 23 switches whether the secondary-side heat medium flowing out of the cascade heat exchanger 13 flows into the upper inlet 71 or the middle inlet 76. The inflow switching unit 23 and the middle inlet 76 are connected by a middle pipe 15c.

  Further, the control unit 40 has a switching unit 92. When the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 36 is equal to or higher than the temperature threshold, the switching unit 92 switches the inflow switching unit 23 so that the secondary heat medium flows into the upper inlet 71. When the secondary outlet temperature T2 detected by the secondary outlet temperature sensor 36 is lower than the temperature threshold, the inflow switching unit 23 is switched so that the secondary heat medium flows into the middle inlet 76. The switching means 92 is, for example, a three-way valve. The secondary outlet temperature sensor 36 may be shared with the secondary outlet temperature sensor 33 of the first embodiment.

  Inside the tank 22, a high-temperature secondary-side heat medium is stored in the upper part, and a low-temperature secondary-side heat medium is stored in the lower part. That is, the inside of the tank 22 has a temperature stratification in which the upper portion has a high temperature, the lower portion has a low temperature, and the middle portion has a medium temperature. The conventional hot water supply system has a problem that the temperature stratification in the tank cannot be maintained. In the seventh embodiment, the high-temperature secondary-side heat medium flows into the tank 22 from the upper inlet 71 through the primary-side outlet pipe 14a and is stored. The medium-temperature secondary-side heat medium flows into the tank 22 from the central inlet 76 through the central pipe 15c and is stored. Thereby, it is possible to suppress the temperature stratification inside the tank 22 from being broken.

Embodiment 8 FIG.
FIG. 14 is a circuit diagram showing a hot water supply system 8 according to Embodiment 8 of the present invention. The eighth embodiment is different from the first embodiment in that the tank 22 is provided with a middle return opening 77. In the eighth embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 14, the tank 22 is provided with a middle return port 77 in addition to the upper return port 75. The middle return port 77 is provided below the upper return port 75, and the secondary heat medium supplied to the supply target is returned and flows in from the middle return pipe 54b. Further, the return pipe 54 is provided with a return switching unit 24. The return switching unit 24 switches whether the secondary heat medium supplied and returned from the tank 22 to the supply target flows into the upper return port 75 or the middle return port 77. The return switching unit 24 and the upper return port 75 are connected by an upper return pipe 54a, and the return switch unit 24 and the middle return port 77 are connected by a middle return pipe 54b. Further, the return pipe 54 is provided with a return temperature sensor 37. The return temperature sensor 37 is a sensor that detects the return temperature of the secondary heat medium supplied from the tank 22 to the supply target and returned.

  Further, the control unit 40 has a switching unit 93. When the return temperature detected by the return temperature sensor 37 is equal to or greater than the return temperature threshold, the switching unit 93 switches the return switching unit 24 so that the secondary heat medium flows into the upper return port 75. When the detected return temperature is lower than the return temperature threshold, the return switching unit 24 is switched so that the secondary heat medium flows into the middle return port 77. The switching means 93 is, for example, a three-way valve.

  Inside the tank 22, a high-temperature secondary-side heat medium is stored in the upper part, and a low-temperature secondary-side heat medium is stored in the lower part. That is, the inside of the tank 22 has a temperature stratification in which the upper portion has a high temperature, the lower portion has a low temperature, and the middle portion has a medium temperature. The conventional hot water supply system has a problem that the temperature stratification in the tank cannot be maintained. In Embodiment 8, when the hot water is returned after the hot water is supplied, the high-temperature secondary-side heat medium flows into the tank 22 from the upper return port 75 through the upper return pipe 54a and is stored. When the hot water is returned after the hot water is supplied, the secondary-side heat medium having a middle temperature flows into the tank 22 from the middle return port 77 through the middle return pipe 54b and is stored therein. Thereby, it is possible to suppress the temperature stratification inside the tank 22 from being broken.

Embodiment 9 FIG.
FIG. 15 is a circuit diagram showing a hot water supply system 9 according to Embodiment 9 of the present invention. The ninth embodiment is different from the first embodiment in that the tank 22 is provided with a middle supply port 78 and a middle return port 77. In the ninth embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on differences from the first embodiment.

  As shown in FIG. 15, the tank 22 is provided with a middle supply port 78 in addition to the upper supply port 73. The middle supply port 78 is provided below the upper supply port 73, is connected to the middle supply pipe 55 in the middle of the tank 22, and is an opening through which the secondary-side heat medium flows into the supply target. The tank 22 is provided with a middle return port 77 in addition to the upper return port 75. The middle return port 77 is provided below the upper return port 75, and the secondary heat medium supplied to the supply target is returned and flows in from the middle return pipe 54b. The tank 22 is provided with a middle temperature sensor 38 in addition to the tank temperature sensor 35. The middle temperature sensor 38 is a sensor that is provided below the tank temperature sensor 35 and detects the temperature of the middle of the tank 22. The temperature of the center of the tank 22 can be grasped by the middle temperature sensor 38.

  In the ninth embodiment, the high-temperature secondary-side heat medium supplied from the supply pipe 51 flows into the tank 22 from the upper return port 75 through the return pipe 53 when the hot water is returned after the supply of hot water. Is done. Further, the intermediate-temperature secondary-side heat medium supplied from the central supply pipe 55 flows into the tank 22 from the central return port 77 through the central return pipe 54b and is stored when the hot water is returned after the hot water is supplied. That is, in the ninth embodiment, two-temperature extraction is performed. Thereby, the temperature stratification inside the tank 22 is not destroyed, and a large amount of the low-temperature secondary-side heat medium accumulates in the lower portion of the tank 22. As described above, since a large amount of the low-temperature secondary-side heat medium accumulates in the lower portion of the tank 22, the secondary-side heat medium flowing out from the lower outlet 72 is kept at a low temperature. Therefore, the temperature of the primary heat medium entering the heat source unit 11 can be kept low.

  1, 2, 3, 4, 5, 6, 7, 8, 9 hot water supply system, 11 heat source unit, 11a heat pump circuit, 12 heating section, 13 cascade heat exchanger, 14 primary side circulation circuit, 14a primary side outlet pipe, 14b Primary inlet piping, 14c Primary piping, 15 Secondary circulation circuit, 15a Secondary outlet piping, 15b Secondary inlet piping, 15c Middle piping, 15d Secondary piping, 16 Primary pump, 17 Secondary Side pump, 18 Primary flow control valve, 19 Secondary flow control valve, 20 Primary flow sensor, 21 Secondary flow sensor, 22 Tank, 23 Inflow switching unit, 24 Return switching unit, 31 Primary inlet temperature sensor , 32 Primary outlet temperature sensor, 33 Secondary outlet temperature sensor, 34 Secondary inlet temperature sensor, 35 Tank temperature sensor, 36 Secondary outlet temperature sensor, 3 7 Return temperature sensor, 38 Middle temperature sensor, 40 control unit, 40a Primary control unit, 40b Secondary control unit, 51 supply pipe, 52 supply pipe, 53 return pipe, 54 return pipe, 54a top return pipe, 54b middle part Return pipe, 55 middle supply pipe, 56 middle return pipe, 60 buffer tank, 61 compressor, 62 expansion section, 63 heat source heat exchanger, 71 upper inlet, 72 lower outlet, 73 upper supply port, 74 supply port, 75 upper part Return port, 76 central inlet, 77 central return port, 78 central supply port, 81 flow control means, 82 first determination means, 83 second determination means, 85 notification means, 86 abnormality determination means, 87 map creation means, 88 flow rate determining means, 89 abnormal stopping means, 90 target setting means, 91 flow rate calculating means, 92 switching means, 93 switching means.

In the hot water supply system according to the present invention, the heating unit that heats the primary heat medium, and a cascade heat exchanger that exchanges heat between the primary heat medium and the secondary heat medium are connected by a primary pipe, and the primary heat A primary-side circulation circuit in which the medium circulates, a cascade heat exchanger, and a tank that stores the secondary-side heat medium are connected by a secondary-side pipe, and a secondary-side circulation circuit in which the secondary-side heat medium circulates, A secondary outlet temperature sensor that detects the secondary outlet temperature of the secondary heat medium flowing out of the cascade heat exchanger, and a secondary outlet temperature detected by the secondary outlet temperature sensor is a secondary target temperature. To a temperature, a control unit having flow control means for controlling the primary circulation flow rate of the primary heat medium and the secondary circulation flow rate of the secondary heat medium , a heat source unit having a heating unit, and a heating unit Detects primary outlet temperature of primary heat medium flowing out Comprising a primary outlet temperature sensor, the that, the control unit, when an abnormality occurs, the abnormal stop means for stopping the operation of the heat source unit, a primary-side outlet temperature detected by the primary side outlet temperature sensor, secondary Abnormality determining means for determining whether the difference from the side outlet temperature has exceeded the temperature difference threshold, and the abnormality stopping means determines whether the difference between the primary side outlet temperature and the secondary side outlet temperature by the abnormality determining means. When it is determined that the temperature difference threshold has been exceeded, the operation of the heat source unit is stopped .

Claims (24)

A heating section for heating the primary heat medium, a cascade heat exchanger for exchanging heat between the primary heat medium and the secondary heat medium are connected by a primary pipe, and a primary side on which the primary heat medium circulates. Circulation circuit,
The cascade heat exchanger, a tank for storing the secondary heat medium is connected by a secondary pipe, a secondary circulation circuit in which the secondary heat medium circulates,
A secondary outlet temperature sensor that detects a secondary outlet temperature of the secondary heat medium flowing out of the cascade heat exchanger,
The secondary-side outlet temperature detected by the secondary-side outlet temperature sensor becomes the secondary-side target temperature, so that the primary-side heat medium has a primary-side circulation flow rate and the secondary-side heat medium has a secondary-side circulation. A control unit having flow control means for controlling the flow rate,
Hot water supply system equipped with. The control unit includes:
A mode setting means for setting the primary circulation flow rate and the secondary circulation flow rate to the same flow control mode in which the same circulation control mode is provided,
The flow control means,
The hot water supply system according to claim 1, wherein in the same flow rate control mode, control is performed such that the primary circulation flow rate and the secondary circulation flow rate are the same. Further comprising a primary exit temperature sensor for detecting a primary exit temperature of the primary heat medium flowing out of the heating unit,
The flow control means,
The secondary-side outlet temperature, the primary-side circulating flow rate, the secondary-side circulating flow rate, and the primary-side outlet temperature detected by the primary-side outlet temperature sensor, based on the primary-side target temperature or the secondary-side temperature The hot water supply system according to claim 1, wherein the target flow rate is controlled. The control unit includes:
A difference between the secondary-side outlet temperature and the secondary-side target temperature, having an abnormality determination unit that determines whether the difference exceeds a secondary-side temperature difference threshold,
The system according to claim 1, further comprising: a notification unit that reports an abnormality when the abnormality determination unit determines that a difference between the secondary-side exit temperature and the secondary-side target temperature exceeds a secondary-side temperature difference threshold. The hot water supply system according to any one of Items 1 to 3. Further comprising a heat source unit having the heating unit,
The control unit includes:
The hot water supply system according to any one of claims 1 to 4, further comprising an abnormal stop unit that stops operation of the heat source unit when an abnormality occurs. Further comprising a primary exit temperature sensor for detecting a primary exit temperature of the primary heat medium flowing out of the heating unit,
The control unit includes:
An abnormality determination unit that determines whether a difference between the primary outlet temperature detected by the primary outlet temperature sensor and the secondary outlet temperature has exceeded a temperature difference threshold,
The abnormal stop means,
The hot water supply system according to claim 5, wherein when the abnormality determination unit determines that a difference between the primary outlet temperature and the secondary outlet temperature exceeds a temperature difference threshold, the operation of the heat source unit is stopped. The control unit includes:
Map creating means for creating a primary flow map indicating the flow rate of the primary heat medium in the primary circulation circuit and a secondary flow map indicating a flow rate of the secondary heat medium in the secondary circulation circuit. When,
The difference between the flow rate value of the primary flow rate map created by the map creation means and the amount of the primary heat medium actually flowing exceeds a primary flow rate difference threshold, or created by the map creation means. Flow rate determining means for determining whether the difference between the flow rate value of the secondary flow rate map and the flow rate of the secondary heat medium that actually flows exceeds a secondary flow rate difference threshold,
The abnormal stop means,
By the flow rate determining means, the difference between the flow rate value of the primary flow map and the amount of the primary heat medium actually flowing exceeds the primary flow rate difference threshold, or the flow value of the secondary flow map. The hot water supply system according to claim 5, wherein the operation of the heat source unit is stopped when it is determined that the difference from the amount of the secondary heat medium that actually flows exceeds the secondary flow rate difference threshold. The control unit includes:
The secondary-side target temperature further includes a target setting unit configured to set a temperature at which a deposition amount of scale that deposits on the secondary-side pipe is less than a deposition amount threshold, according to any one of claims 1 to 7. Hot water supply system. The hot water supply system according to any one of claims 1 to 8, further comprising a buffer tank provided in the primary side circulation circuit and storing the primary side heat medium. A primary pump provided in the primary circulation circuit and transporting the primary heat medium, further comprises:
The flow control means,
The hot water supply system according to any one of claims 1 to 9, wherein the primary side circulation flow rate is controlled by the primary side pump. A secondary pump provided in the secondary circulation circuit and transporting the secondary heat medium is further provided.
The flow control means,
The hot water supply system according to any one of claims 1 to 10, wherein the secondary circulation flow rate is controlled by the secondary pump. The secondary pump,
The hot water supply system according to claim 11, which is an inverter pump. The apparatus further includes a primary-side flow rate adjustment valve that is provided in the primary-side circulation circuit and adjusts the primary-side circulation flow rate,
The flow control means,
The hot water supply system according to any one of claims 1 to 12, wherein the primary circulation flow rate is controlled by the primary flow control valve. The secondary-side circulation circuit further includes a secondary-side flow rate adjustment valve that adjusts the secondary-side circulation flow rate,
The flow control means,
The hot water supply system according to any one of claims 1 to 13, wherein the secondary circulation flow rate is controlled by the secondary flow rate control valve. A primary flow sensor provided in the primary circulation circuit and detecting the primary circulation flow rate is further provided.
The flow control means,
The hot water supply system according to any one of claims 1 to 14, wherein the primary-side circulation flow rate detected by the primary-side flow rate sensor is controlled to be a primary-side target flow rate. A secondary flow sensor is provided in the secondary circulation circuit, and further includes a secondary flow sensor that detects the secondary circulation flow rate.
The flow control means,
The hot water supply system according to any one of claims 1 to 15, wherein the secondary circulation flow rate detected by the secondary flow rate sensor is controlled to be a secondary target flow rate. The hot water supply system according to any one of claims 1 to 16, further comprising a primary inlet temperature sensor that detects a primary inlet temperature of the primary heat medium flowing into the heating unit. Further comprising a secondary inlet temperature sensor for detecting a secondary inlet temperature of the secondary heat medium flowing into the cascade heat exchanger,
The control unit includes:
The flow rate calculating means for calculating the secondary-side circulation flow rate based on the secondary-side outlet temperature and the secondary-side inlet temperature detected by the secondary-side inlet temperature sensor, further comprising: The hot water supply system according to claim 1. Further comprising a heat source unit having the heating unit,
The control unit includes:
The hot water supply system according to any one of claims 1 to 18, wherein the hot water supply system is provided in the heat source unit. The control unit includes:
A primary-side control unit that controls the operation of the primary-side circulation circuit,
The hot water supply system according to any one of claims 1 to 19, further comprising: a secondary-side control unit that controls an operation of the secondary-side circulation circuit. A tank temperature sensor is provided on the upper portion of the tank, and further detects a tank temperature of the secondary heat medium stored in the tank,
The control unit includes:
The hot water supply system according to any one of claims 1 to 20, further comprising target setting means for setting a primary target temperature and a secondary target temperature based on the tank temperature detected by the tank temperature sensor. In the tank,
An upper inlet provided at an upper portion, through which the secondary heat medium flowing out of the cascade heat exchanger flows,
A central inlet provided below the upper inlet and into which the secondary heat medium flowing out of the cascade heat exchanger flows,
An inflow switching unit that switches whether the secondary heat medium flowing out of the cascade heat exchanger flows into the upper inlet or the middle inlet is further provided.
The control unit includes:
When the secondary outlet temperature is equal to or higher than the temperature threshold, the inflow switching unit is switched so that the secondary heat medium flows into the upper inlet, and when the secondary outlet temperature is lower than the temperature threshold, The hot water supply system according to any one of claims 1 to 21, further comprising a switching unit configured to switch the inflow switching unit so that the secondary heat medium flows into the middle inlet. In the tank,
An upper return port provided at an upper portion, into which the secondary side heat medium supplied to the supply target is returned and flows,
A middle return port is provided below the upper return port, and the secondary heat medium supplied to the supply target is returned and flows therethrough.
A return temperature sensor that detects a return temperature of the secondary heat medium that is supplied and returned from the tank to a supply target,
A return switching unit that switches whether the secondary heat medium supplied and returned from the tank to the supply target flows into the upper return port or the middle return port,
The control unit includes:
When the return temperature detected by the return temperature sensor is equal to or greater than the return temperature threshold, the return switching unit is switched so that the secondary-side heat medium flows into the upper return port, and the return temperature is less than the return temperature threshold. In the case, the hot water supply system according to any one of claims 1 to 22, further comprising a switching unit that switches the return switching unit so that the secondary heat medium flows into the middle return port. In the tank,
An upper supply port that is provided at an upper portion and the secondary heat medium flows out to a supply target,
A central supply port that is provided below the upper supply port, and the secondary-side heat medium flows out to a supply target,
An upper return port provided at an upper portion, wherein the secondary heat medium that has flowed out of the upper supply port and supplied to the supply target is returned and flows in,
A central return port provided below the upper return port to return the secondary side heat medium supplied from the central supply port to the supply target and supplied to the supply target; 24. The hot water supply system according to any one of items 23 to 23.

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