Hot water supply system

Abstract

A hot water supply system (1) comprises: a vapor compression heat pump circuit (10) which connects a compressor (11), a first heat dissipation heat exchanger (12A), a second heat dissipation heat exchanger (12B), an expansion valve (13) and a heat absorption heat exchanger (14) in a ring shape via a refrigerant circulation line (L9); the first heat dissipation heat exchanger (12A) and / or the second heat dissipation heat exchanger (12B) are driven by the compressor (11); and a hot water storage tank (60) which stores feed water ( W2); a water circulation line (L1) for circulating stored water (W3) in a hot water storage tank (60) in a first heat dissipation heat exchanger (12A); a feed water line (L2) for circulating feed water (W2) in a second heat dissipation heat exchanger (12B) and supplying the feed water to the hot water storage tank (60); a refrigerant temperature adjustment unit (50) for adjusting the temperature of the liquid refrigerant (R) flowing into the expansion valve (13); and a control unit (100) for controlling the refrigerant temperature adjustment unit (50).

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2020-131897 filed in Japan on August 3, 2020, the contents of which are incorporated herein by reference.

[0002] The invention relates to a hot water supply system. Background Art

[0003] As is well known, the energy efficiency of a heat pump water heater is expressed in terms of COP (coefficient of performance). Various improvements have been made to the refrigeration cycle to improve this COP. For example, Patent Documents 1 and 2 describe a water heating system configured such that a subcooler is provided downstream of the condenser in the heat pump circuit. This system heats the stored water in the hot water tank by circulating it through the condenser, while preheating the feed water supplied to the hot water tank by circulating it through the subcooler.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 2-27582

[0007] Patent Document 2: Japanese Utility Model Application Laid-Open No. 3-3665 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] In a configuration where the stored water in the hot water tank is heated solely by circulating it through a condenser, the temperature difference between the stored water and the heat source air increases as the stored water temperature rises, making it difficult to maintain a high COP. In contrast, the hot water supply systems described in Patent Documents 1 and 2 enhance the overall system heating capacity by preheating the low-temperature makeup water using a subcooler, thereby improving the COP.

[0010] However, in such hot water supply systems, when the make-up water source temperature is low, for example, the liquid refrigerant flowing into the expansion valve may be extremely cooled by passing through the condenser and subcooler. When highly subcooled liquid refrigerant is supplied to the evaporator, wet vapor, insufficiently vaporized in the evaporator, is delivered to the compressor. If the compressor draws in wet vapor, it could be damaged by liquid hammer caused by liquid compression.

[0011] The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a hot water supply system that can prevent damage to a compressor in a structure in which a heat exchanger for heating stored water and a heat exchanger for heating feed water are provided in a heat pump circuit.

[0012] Solutions to Problems

[0013] The present invention relates to a hot water supply system, comprising: a vapor compression heat pump circuit, wherein a compressor, a first heat dissipation heat exchanger, a second heat dissipation heat exchanger, an expansion valve, and a heat absorption heat exchanger are connected in a loop via a refrigerant circulation line, and heat energy is extracted from the first heat dissipation heat exchanger and / or the second heat dissipation heat exchanger by driving the compressor; a hot water storage tank storing make-up water; a water circulation line circulating the stored water in the hot water storage tank through the first heat dissipation heat exchanger; a make-up water line circulating the make-up water through the second heat dissipation heat exchanger and supplying the make-up water to the hot water storage tank; a refrigerant temperature adjustment unit adjusting the temperature of the liquid refrigerant flowing into the expansion valve; and a control unit controlling the refrigerant temperature adjustment unit.

[0014] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor, which detects the temperature of the liquid refrigerant flowing into the expansion valve; a first bypass line, which is connected to the refrigerant circulation line so that the refrigerant bypasses the second heat dissipation heat exchanger; and a first distribution valve, which adjusts the distribution amount of the refrigerant supplied to the second heat dissipation heat exchanger and the refrigerant supplied to the first bypass line, and the control unit controls the first distribution valve in a manner that makes the temperature detected by the temperature sensor become the target temperature during the driving of the compressor.

[0015] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor that detects the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor that detects the pressure of the liquid refrigerant flowing into the expansion valve; a first bypass line that is connected to the refrigerant circulation line so that the refrigerant bypasses the second heat dissipation heat exchanger; and a first distribution valve that adjusts the distribution amount of the refrigerant supplied to the second heat dissipation heat exchanger and the refrigerant supplied to the first bypass line. When driving the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the supercooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the first distribution valve in such a manner that the calculated supercooling degree becomes a target supercooling degree.

[0016] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor, which detects the temperature of the liquid refrigerant flowing into the expansion valve; a second bypass line, which is connected to the feed water line so that the feed water bypasses the second heat exchanger for heat dissipation; and a second distribution valve, which adjusts the distribution amount of the feed water supplied to the second heat exchanger for heat dissipation and the feed water supplied to the second bypass line, and the control unit controls the second distribution valve in a manner that the temperature detected by the temperature sensor becomes the target temperature during the driving of the compressor.

[0017] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor that detects the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor that detects the pressure of the liquid refrigerant flowing into the expansion valve; a second bypass line that is connected to the feed water line so that the feed water bypasses the second heat dissipation heat exchanger; and a second distribution valve that adjusts the distribution amount of the feed water supplied to the second heat dissipation heat exchanger and the feed water supplied to the second bypass line. When driving the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the subcooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the second distribution valve in such a manner that the calculated subcooling degree becomes the target subcooling degree.

[0018] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor, which detects the temperature of the liquid refrigerant flowing into the expansion valve; a third bypass line, which is connected to the refrigerant circulation line so that the refrigerant bypasses the first heat dissipation heat exchanger; and a third distribution valve, which adjusts the distribution amount of the refrigerant supplied to the first heat dissipation heat exchanger and the refrigerant supplied to the third bypass line, and the control unit controls the third distribution valve in a manner that the temperature detected by the temperature sensor becomes the target temperature during the driving of the compressor.

[0019] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor that detects the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor that detects the pressure of the liquid refrigerant flowing into the expansion valve; a third bypass line that is connected to the refrigerant circulation line so that the refrigerant bypasses the first heat dissipation heat exchanger; and a third distribution valve that adjusts the distribution amount of the refrigerant supplied to the first heat dissipation heat exchanger and the refrigerant supplied to the third bypass line. When driving the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the supercooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the third distribution valve in such a manner that the calculated supercooling degree becomes the target supercooling degree.

[0020] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor, which detects the temperature of the liquid refrigerant flowing into the expansion valve; a fourth bypass line, which is connected to the water circulation line so that the circulating water bypasses the first heat dissipation heat exchanger; and a fourth distribution valve, which adjusts the distribution amount of the circulating water supplied to the first heat dissipation heat exchanger and the circulating water supplied to the fourth bypass line, and the control unit controls the fourth distribution valve in a manner that the temperature detected by the temperature sensor becomes the target temperature during the driving of the compressor.

[0021] In addition, preferably, the refrigerant temperature adjustment unit of the hot water supply system includes: a temperature sensor that detects the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor that detects the pressure of the liquid refrigerant flowing into the expansion valve; a fourth bypass line that is connected to the water circulation line so that the circulating water bypasses the first heat dissipation heat exchanger; and a fourth distribution valve that adjusts the distribution amount of the circulating water supplied to the first heat dissipation heat exchanger and the circulating water supplied to the fourth bypass line. When driving the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the supercooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the fourth distribution valve in such a manner that the calculated supercooling degree becomes the target supercooling degree.

[0022] Effects of the Invention

[0023] According to the present invention, there is provided a hot water supply system capable of preventing damage to a compressor in a configuration in which a heat exchanger for heating stored water and a heat exchanger for heating feed water are provided in a heat pump circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a diagram schematically showing the configuration of a hot water supply system according to the first embodiment of the present invention.

[0025] Figure 2 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the above-described embodiment.

[0026] Figure 3 It is a diagram schematically showing the configuration of a hot water supply system according to a second embodiment of the present invention.

[0027] Figure 4 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the above-described embodiment.

[0028] Figure 5 It is a diagram schematically showing the configuration of a hot water supply system according to a third embodiment of the present invention.

[0029] Figure 6 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the above-described embodiment.

[0030] Figure 7 It is a diagram schematically showing the configuration of a water heating system according to a fourth embodiment of the present invention.

[0031] Figure 8 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the above-described embodiment. DETAILED DESCRIPTION

[0032] <First embodiment>

[0033] Hereinafter, a first embodiment of the hot water supply system 1 of the present invention will be described with reference to the accompanying drawings. Note that "pipeline" in this specification is a general term for pipelines such as flow paths, pathways, and pipes through which fluid can flow.

[0034] Figure 1 Schematically shows the structure of the hot water supply system 1 of this embodiment. Figure 1 As shown, the hot water supply system 1 of this embodiment includes a heat pump circuit 10, a hot water storage tank 60, a water circulation line L1 that circulates stored water W3 in the hot water storage tank 60 as circulating water W1, a make-up water line L2 that supplies make-up water W2 to the hot water storage tank 60, and a control unit 100.

[0035] The hot water supply system 1 is a system that supplies stored water W3 in a hot water storage tank 60 heated by a heat pump circuit 10 as hot water W4 to locations requiring hot water or thermal energy.

[0036] Heat pump circuit 10 is a vapor compression heat pump circuit. A compressor 11, a first heat-dissipating heat exchanger 12A (condenser 12A), a second heat-dissipating heat exchanger 12B (subcooler 12B), an expansion valve 13, and a heat-absorbing heat exchanger 14 (evaporator 14) are connected in a loop via a refrigerant circulation line L9. Driven by compressor 11, heat is absorbed by heat-absorbing heat exchanger 14, while heat energy is extracted by first heat-dissipating heat exchanger 12A and / or second heat-dissipating heat exchanger 12B. Refrigerant R flows through this refrigerant circulation line L9.

[0037] The compressor 11 has an electric motor 15 as a driving source, which compresses a gaseous refrigerant R (gas refrigerant R) such as Freon gas to form a high-temperature and high-pressure refrigerant R. The first heat exchanger 12A for heat dissipation is a condenser that condenses and liquefies the refrigerant R from the compressor 11 by dissipating heat to the circulating water W1 supplied through the water circulation line L1. The second heat exchanger 12B for heat dissipation is a subcooler that dissipates heat to the feed water W2 supplied through the feed water line L2 and subcools the refrigerant R (liquid refrigerant R) that has passed through the first heat exchanger 12A for heat dissipation. The expansion valve 13 allows the refrigerant R supplied from the second heat exchanger 12B to pass through, thereby reducing the pressure and temperature of the refrigerant R. The heat exchanger 14 for heat absorption is an evaporator that absorbs heat from the heat source fluid and evaporates the refrigerant R supplied from the expansion valve 13. Various fluids such as heat source air and heat source water can be used as the heat source fluid.

[0038] The first heat exchanger 12A for storing water heating indirectly exchanges heat between the circulating water W1 and the refrigerant R, dissipating latent heat and sensible heat of the refrigerant R. The first heat exchanger 12A condenses and liquefies the refrigerant R using the circulating water W1 and heats the circulating water W1 using the refrigerant R.

[0039] The second heat exchanger 12B for heating the feed water indirectly exchanges heat between the feed water W2 and the refrigerant R to dissipate sensible heat of the refrigerant R. The second heat exchanger 12B uses the feed water W2 to subcool the refrigerant R and also uses the refrigerant R to heat the feed water W2.

[0040] In this way, the heat exchanger is easily designed and cost can be reduced by dividing the heat exchanger into the condensation and subcooling functions of the refrigerant R. In addition, a general-purpose heat exchanger can also be used.

[0041] Note that, depending on operating conditions and the like, when condensation and liquefaction of the gas refrigerant R stops as a local phase change in the first heat exchanger 12A, the remaining gas refrigerant R is condensed and liquefied in the second heat exchanger 12B.

[0042] The expansion valve 13 is configured as a proportional control needle valve. The needle valve stroke is changed by controlling the rotation speed of a driving stepping motor, and the flow rate of the refrigerant R flowing in the refrigerant circulation line L9 can be adjusted by adjusting the valve opening.

[0043] As described above, in the heat pump circuit 10, the refrigerant R absorbs heat from the outside and vaporizes in the heat-absorbing heat exchanger 14. Meanwhile, in the first and second heat-dissipating heat exchangers 12A, 12B, the refrigerant R dissipates heat to the outside, condensing and liquefying, thereby being subcooled. Using this principle, the heat pump circuit 10 extracts heat from the heat source fluid in the heat-absorbing heat exchanger 14, heats the circulating water W1 in the first heat-dissipating heat exchanger 12A, and heats the feed water W2 in the second heat-dissipating heat exchanger 12B.

[0044] The heat pump circuit 10 of this embodiment also includes a refrigerant temperature sensor 16 as a temperature sensor for detecting the temperature of the liquid refrigerant R flowing into the expansion valve 13, a first bypass line L11 connected to the refrigerant circulation line L9 and allowing the liquid refrigerant R to bypass the second heat exchanger 12B for heat dissipation, and a first distribution valve 31 for adjusting the distribution amount of the liquid refrigerant R supplied to the second heat exchanger 12B for heat dissipation and the liquid refrigerant R supplied to the first bypass line L11.

[0045] The first bypass line L11 branches off from the refrigerant circulation line L9 on the upstream side of the second heat exchanger 12B for heat dissipation (between the first heat exchanger 12A and the second heat exchanger 12B for heat dissipation) and merges with the refrigerant circulation line L9 on the downstream side of the second heat exchanger 12B for heat dissipation (between the second heat exchanger 12B for heat dissipation and the expansion valve 13).

[0046] The refrigerant temperature sensor 16 is disposed downstream of the confluence of the refrigerant circulation line L9 and the first bypass line L11 and upstream of the expansion valve 13. More preferably, the refrigerant temperature sensor 16 is disposed upstream of the expansion valve 13 and in the vicinity of the expansion valve 13 in order to measure the temperature of the refrigerant R immediately before it flows into the expansion valve 13.

[0047] The first distributing valve 31 is provided in the first bypass line L11. The first distributing valve 31 is configured to have an adjustable valve opening. Adjusting the valve opening of the first distributing valve 31 adjusts the amount of liquid refrigerant R supplied to the second heat exchanger 12B and to the first bypass line L11.

[0048] Here, when the first distributing valve 31 is open, the first subflow of refrigerant R flowing through the refrigerant circulation line L9, which flows through the first bypass line L11, only experiences relatively small friction losses within the valve chamber while passing through the first distributing valve 31. Meanwhile, the second subflow flowing through the refrigerant circulation line L9, where the second heat dissipation heat exchanger 12B is located, experiences relatively large friction losses within the second heat dissipation heat exchanger 12B while passing through the second heat dissipation heat exchanger 12B. Consequently, the refrigerant R flow rate ratio becomes "first subflow > second subflow," with the majority of refrigerant R flowing through the first bypass line L11. Therefore, even with this simple configuration, the amount of liquid refrigerant R supplied to the second heat dissipation heat exchanger 12B and the amount of liquid refrigerant R supplied to the first bypass line L11 can be adjusted by adjusting the valve opening of the first distributing valve 31.

[0049] The refrigerant temperature sensor 16 , the first bypass line L11 , and the first distribution valve 31 constitute a refrigerant temperature adjustment unit 50 of this embodiment. The refrigerant temperature adjustment unit 50 is controlled by a control unit 100 described later and adjusts the temperature of the liquid refrigerant R flowing into the expansion valve 13 .

[0050] The hot water tank 60 stores circulating water W1 and makeup water W2 heated by the heat pump circuit 10 as stored water W3. The stored water W3 in the hot water tank 60 is supplied as hot water W4 to locations requiring hot water or thermal energy via a hot water supply line L4.

[0051] The hot water tank 60 includes a hot water temperature sensor 61 for detecting the temperature of the stored water W3 in the hot water tank 60. The hot water temperature sensor 61 monitors the temperature of the stored water W3 supplied as hot water W4 to a location requiring hot water or a location requiring thermal energy.

[0052] The hot water tank 60 is equipped with a water level sensor 62 for detecting the water level within the hot water tank 60. In this embodiment, the water level sensor 62 is an electrode-type water level detector comprising multiple electrode rods. Specifically, multiple electrode rods of varying lengths are inserted and held at different heights. Each electrode rod detects the presence or absence of water at its lower end by determining whether its lower end is immersed in water. Thus, the water level sensor 62 detects the water level of the stored water W3 within the hot water tank 60.

[0053] The water circulation line L1 is connected to the hot water tank 60 on its upstream side and also on its downstream side. The water circulation line L1 forms a circulation path that circulates the stored water W3 in the hot water tank 60 as circulating water W1. The stored water W3 in the hot water tank 60 passes through the water circulation line L1 and is heated by the first heat exchanger 12A, returning to the hot water tank 60. Disposed along the water circulation line L1, from the upstream side, are a water circulation pump 21, the first heat exchanger 12A, and a first temperature sensor 22.

[0054] The rotation speed of the water circulation pump 21 can be controlled by an inverter. By changing the rotation speed of the water circulation pump 21, the flow rate of the circulating water W1 circulating in the water circulation line L1 can be adjusted.

[0055] The first temperature sensor 22 is disposed on the downstream side of the first heat exchanger 12A for heat radiation, and detects the temperature of the circulating water W1 flowing out of the first heat exchanger 12A for heat radiation.

[0056] The upstream side of the makeup water line L2 is connected to a makeup water source such as a makeup water tank (not shown), and the downstream side is connected to the hot water storage tank 60. The makeup water line L2 is a line that flows makeup water W2 toward the second heat exchanger 12B and supplies it to the hot water storage tank 60. The makeup water line L2 is provided with, in order from the upstream side, a makeup water valve 25, the second heat exchanger 12B, and a second temperature sensor 26.

[0057] The makeup water valve 25 is configured to be able to adjust the valve opening. By adjusting the valve opening of the makeup water valve 25, the flow rate of the makeup water W2 flowing through the makeup water line L2 can be adjusted.

[0058] The second temperature sensor 26 is disposed on the downstream side of the second heat exchanger 12B for heat radiation, and detects the temperature of the makeup water W2 flowing out of the second heat exchanger 12B for heat radiation.

[0059] The makeup water line L2 includes a second bypass line L12 serving as a makeup water bypass line. The second bypass line L12 allows the makeup water W2 to bypass the second heat exchanger 12B. A second distribution valve 32 serving as a makeup water distribution valve is disposed on the second bypass line L12.

[0060] The second distribution valve 32 adjusts the amount of makeup water W2 supplied to the second heat exchanger 12B and to the second bypass line L12. The second distribution valve 32 can also be opened automatically or manually by a valve opening adjustment. For example, if a sudden drop in the water level of the stored water W3 in the hot water storage tank 60 is detected, the second distribution valve 32 can be opened automatically or manually. This allows the makeup water W2, which has not been heated by the second heat exchanger 12B, to be rapidly supplied to the hot water storage tank 60, preventing the hot water storage tank 60 from running out of water.

[0061] The stored water W3 in the hot water storage tank 60 heated by the water circulation line L1 and the makeup water line L2 is supplied as hot water W4 to a location requiring hot water or a location requiring thermal energy through the hot water supply line L4.

[0062] Hot water-requiring locations refer to various production facilities within a factory that consume stored water W3 by utilizing hot water W4 for fluid utilization. Examples of hot water-requiring locations include equipment for washing containers (rinsers) for food, beverages, and pharmaceuticals, and equipment for heating and sterilizing bottled, boxed, and bagged products (pasteurizers).

[0063] On the other hand, heat-requiring locations include production equipment, for example, that utilizes only the thermal energy of the hot water W4 without consuming the stored water W3. Thermal energy is utilized via various heat exchangers, and the hot water W4, whose temperature has been lowered by the extraction of thermal energy, is returned to the hot water storage tank 60 via a return hot water line (not shown). Examples of heat-requiring locations include degreasing tanks and chemical conversion tanks in metalworking equipment, and air handling units in air conditioning equipment.

[0064] Next, the control unit 100 (control unit 100) of the hot water supply system 1 of this embodiment will be described. The control unit 100 is composed of a microprocessor including a CPU and memory. The control unit 100 includes a water circulation pump control unit 110 as a circulating water flow rate control unit, a makeup water valve control unit 120 as a makeup water flow rate control unit, and a distribution valve control unit 130 as a refrigerant temperature control unit as functional blocks.

[0065] Here, Figure 1 The dotted lines in FIG. 1 represent the main electrical connection paths of this embodiment. It should be noted that these electrical connections actually pass through the control unit 100, but this point is omitted.

[0066] The water circulation pump control unit 110 obtains the temperature detected by the first temperature sensor 22 and controls the drive frequency of the water circulation pump 21, which constitutes the circulating water flow adjustment unit, based on the detected temperature. Specifically, the water circulation pump control unit 110 controls the drive frequency of the water circulation pump 21 and adjusts the flow rate of the circulating water W1 so that the temperature detected by the first temperature sensor 22 reaches the target outlet heated water temperature. As a more specific control, for example, the following feedback control is preferably adopted: using the outlet heated water temperature detected in real time by the first temperature sensor 22 as a feedback value, the drive frequency of the water circulation pump is adjusted so that the outlet heated water temperature approaches the target outlet heated water temperature. In addition to proportional control (P control), feedback control can also adopt an operation algorithm that combines the operation amount of integral control (I control) and / or differential control (D control).

[0067] Thus, the circulating water W1 supplied from the hot water tank 60 to the first heat dissipation heat exchanger 12A is heated to the target hot water outlet temperature (e.g., 60°C) by the first heat dissipation heat exchanger 12A, and then returns to the hot water tank 60 at a constant temperature. Therefore, even if the temperature of the heat source fluid (e.g., heat source air) supplied to the heat absorption heat exchanger 14 fluctuates seasonally, or even if the temperature of the makeup water W2 heated by the second heat dissipation heat exchanger 12B fluctuates, hot water at a desired temperature (e.g., the hot water supply temperature required by a hot water-demanding area or a thermal energy-demanding area) can be quickly stored in the hot water tank 60.

[0068] The makeup water valve control unit 120 obtains water level information of the stored water W3 in the hot water storage tank 60, detected by the water level sensor 62. Based on this water level information, it controls the valve opening of the makeup water valve 25, which constitutes the makeup water flow rate adjustment unit. Specifically, the makeup water valve control unit 120 controls the makeup water valve 25 so that the makeup water flow rate decreases as the water level detected by the water level sensor 62 increases. Conversely, the makeup water valve 25 opens so that the makeup water flow rate increases as the water level detected by the water level sensor 62 decreases. For example, when the water level is full, the makeup water valve 25 opens to 0% (fully closed). At a level just before water shortage, the valve opening is set to 100% (fully open). At intermediate water levels, the valve opening of the makeup water valve 25 is set to between 5% and 95%.

[0069] In this way, the valve opening of the makeup water valve 25 decreases as the water level detected by the water level sensor 62 increases, while the valve opening of the makeup water valve 25 increases as the water level detected by the water level sensor 62 decreases. Consequently, the makeup water flow rate increases or decreases in response to increases or decreases in the demand for hot water. Specifically, as long as the demand for hot water does not reach zero, the makeup water valve 25 remains open, and makeup water W2 continues to flow to the second heat dissipation heat exchanger 12B. This allows for continued subcooling of the liquid refrigerant R, even when the demand for hot water is low, thereby improving the COP.

[0070] Note that the makeup water valve control unit 120 may also control the valve opening of the makeup water valve 25 based on the temperature detected by the second temperature sensor 26, which detects the temperature of the makeup water W2 flowing out of the second heat dissipation heat exchanger 12B, in addition to the water level detected by the water level sensor 62. In this case, the makeup water valve control unit 120 adjusts the valve opening of the makeup water valve 25, which constitutes the makeup water flow rate adjustment unit, based on the water level information detected by the water level sensor 62. Furthermore, if the temperature detected by the second temperature sensor 26 exceeds the target outlet heated water temperature (e.g., 60°C) of the first heat dissipation heat exchanger 12A, the valve opening of the makeup water valve 25 is controlled so that the temperature detected by the second temperature sensor 26 does not exceed the target outlet heated water temperature (e.g., 60°C). This allows for the rapid supply of hot water to the hot water storage tank 60 at a temperature not exceeding the required temperature (e.g., the hot water supply temperature required by a hot water-demanding area or a thermal energy-demanding area) while maintaining subcooling of the liquid refrigerant R.

[0071] The distribution valve control unit 130 obtains the temperature detected by the refrigerant temperature sensor 16 and, based on the detected temperature, controls the valve opening of the first distribution valve 31 constituting the refrigerant temperature adjustment unit 50. Specifically, the distribution valve control unit 130 controls the first distribution valve 31 during the operation of the compressor 11 so that the temperature detected by the refrigerant temperature sensor 16 reaches the target temperature. As a more specific control, for example, the following feedback control is preferably employed: using the refrigerant temperature detected in real time by the refrigerant temperature sensor 16 as a feedback value, the valve opening of the first distribution valve 31 is adjusted so that the refrigerant temperature approaches the target temperature. In addition to proportional control (P control), feedback control can also employ an operation algorithm that combines an operation variable with integral control (I control) and / or differential control (D control).

[0072] Here, the target temperature is set manually or automatically according to the device status and the like.

[0073] Thus, the amount of the liquid refrigerant R bypassing the second heat exchanger 12B for heat dissipation is adjusted, and the amount of cooling of the liquid refrigerant R in the second heat exchanger 12B for heat dissipation is suppressed.

[0074] The above configuration allows the temperature of the liquid refrigerant R flowing into the expansion valve to be maintained at a constant temperature, preventing it from becoming excessively subcooled, even when the source temperature of the makeup water is low. This prevents the supply of highly subcooled liquid refrigerant R to the heat-absorbing heat exchanger 14, and prevents the compressor 11 from being hindered from sucking in wet vapor refrigerant R. This prevents damage to the compressor 11 and allows the refrigeration cycle to operate optimally.

[0075] Next, a modification of the first embodiment will be described with reference to the drawings. Figure 2 This diagram schematically illustrates the configuration of a hot water supply system according to a modified example of the first embodiment. In this modified example, a refrigerant pressure sensor 17 is further provided for detecting the pressure of the liquid refrigerant R flowing into the expansion valve 13. A distribution valve control unit 130 controls the first distribution valve 31 based on the temperature detected by the refrigerant temperature sensor 16 and the pressure detected by the refrigerant pressure sensor 17.

[0076] like Figure 2 As shown, the heat pump circuit 10 of this modification includes a refrigerant pressure sensor 17 for detecting the pressure of the liquid refrigerant R flowing into the expansion valve 13. In addition, the control unit 100 of this modification includes a subcooling degree calculation unit 140 for calculating the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13.

[0077] The refrigerant pressure sensor 17, like the refrigerant temperature sensor 16, is disposed downstream of the confluence of the refrigerant circulation line L9 and the first bypass line L11 and upstream of the expansion valve 13. More preferably, the refrigerant pressure sensor 17 is disposed upstream of the expansion valve 13 and in the vicinity of the expansion valve 13 in order to measure the pressure of the refrigerant R immediately before it flows into the expansion valve 13.

[0078] In this modification, the refrigerant pressure sensor 17 , the refrigerant temperature sensor 16 , the first bypass line L11 , and the first distribution valve 31 constitute a refrigerant temperature adjustment unit 50 .

[0079] The subcooling degree calculation unit 140 calculates the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13. Specifically, the subcooling degree calculation unit 140 obtains the condensation temperature of the gas refrigerant R based on the pressure detected by the refrigerant pressure sensor 17, and calculates the subcooling degree of the liquid refrigerant R by subtracting the temperature detected by the refrigerant temperature sensor 16 from the condensation temperature.

[0080] The distributing valve control unit 130 controls the first distributing valve 31 constituting the refrigerant temperature adjustment unit 50 so that the calculated degree of subcooling (based on the value calculated by the degree of subcooling calculation unit 140) reaches the target degree of subcooling, thereby adjusting the degree of subcooling of the liquid refrigerant R flowing into the expansion valve 13. Specifically, feedback control is preferably employed, for example, in which the valve opening of the first distributing valve 31 is adjusted so that the calculated degree of subcooling, calculated in real time by the degree of subcooling calculation unit 140, approaches the target degree of subcooling, using the calculated degree of subcooling as a feedback value. Feedback control can employ, in addition to proportional control (P control), a calculation algorithm that combines the manipulated variable with integral control (I control) and / or differential control (D control).

[0081] Thus, the amount of the liquid refrigerant R bypassing the second heat exchanger 12B for heat dissipation is adjusted, and the degree of subcooling of the liquid refrigerant R flowing into the expansion valve 13 is adjusted.

[0082] Here, the target degree of subcooling is set manually or automatically according to the device status and the like.

[0083] In this manner, the subcooling degree calculation unit 140 accurately calculates the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13, and the distribution valve control unit 130 controls the first distribution valve 31 so that the calculated subcooling degree reaches the target subcooling degree. This adjusts the amount of liquid refrigerant R bypassing the second heat exchanger 12B, thereby suppressing the amount of cooling of the liquid refrigerant R in the second heat exchanger 12B. Consequently, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0084] It should be noted that in this embodiment, the first distributing valve 31 is provided in the first bypass line L11, but this is not limiting. The first distributing valve 31 only needs to have the function of adjusting the amount of liquid refrigerant R supplied to the second heat dissipation heat exchanger 12B and the amount of liquid refrigerant R supplied to the first bypass line L11. For example, it may be a three-way valve provided at the branching portion where the first bypass line L11 branches off from the refrigerant circulation line L9.

[0085] In the case of a three-way valve, a valve opening command signal ranging from 0 to 100% is input to the actuator circuit that adjusts the valve opening. This adjusts the valve opening on the first outlet port side of the second heat dissipation heat exchanger 12B and the valve opening on the second outlet port side of the first bypass line U1. This adjusts the flow rate ratio between the liquid refrigerant R flowing into the second heat dissipation heat exchanger 12B and the liquid refrigerant R flowing into the first bypass line L11. However, the sum of the flow rate ratios on the first and second outlet ports is always 100%. The three-way valve opening is based on the valve opening on the first outlet port. If the valve opening on the first outlet port changes from 0% to 25% to 50% to 75% to 100%, the valve opening on the second outlet port changes from 100% to 75% to 50% to 25% to 0%. When using such a three-way valve, for example, the following feedback control is preferably adopted: the refrigerant temperature detected in real time by the refrigerant temperature sensor 16 and the calculated subcooling degree calculated in real time by the subcooling degree calculation unit 140 are used as feedback values to adjust the valve opening of the three-way valve in such a way that these refrigerant temperature and calculated subcooling degree approach the target value.

[0086] According to the hot water supply system 1 of the first embodiment described above, the following effects (1) to (3) are achieved.

[0087] (1) The hot water supply system 1 of this embodiment includes: a vapor compression heat pump circuit 10, which connects a compressor 11, a first heat dissipation heat exchanger 12A, a second heat dissipation heat exchanger 12B, an expansion valve 13, and a heat absorption heat exchanger 14 in a loop via a refrigerant circulation line L9, and extracts heat energy from the first heat dissipation heat exchanger 12A and / or the second heat dissipation heat exchanger 12B by driving the compressor 11; a hot water storage tank 60, which stores feed water W2; a water circulation line L1, which circulates the stored water W3 in the hot water storage tank 60 through the first heat dissipation heat exchanger 12A; a feed water line L2, which flows the feed water W2 through the second heat dissipation heat exchanger 12B and supplies it to the hot water storage tank 60; a refrigerant temperature adjustment unit 50, which adjusts the temperature of the liquid refrigerant R flowing into the expansion valve 13; and a control unit 100, which controls the refrigerant temperature adjustment unit 50.

[0088] Thus, the provision of the refrigerant temperature adjustment unit 50 for adjusting the temperature of the liquid refrigerant R flowing into the expansion valve 13 and the control unit 100 for controlling the refrigerant temperature adjustment unit 50 prevents the supply of highly subcooled refrigerant R to the heat-absorbing heat exchanger 14 (evaporator 14), thereby preventing the compressor 11 from being hindered from sucking in wet vapor. This prevents damage to the compressor 11 and allows the refrigeration cycle to operate optimally.

[0089] (2) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a first bypass line L11, which is connected to the refrigerant circulation line L9, so that the refrigerant R bypasses the second heat exchanger 12B for heat dissipation; and a first distribution valve 31, which adjusts the distribution amount of the refrigerant R supplied to the second heat exchanger 12B for heat dissipation and the refrigerant R supplied to the first bypass line L11. The control unit 100 controls the first distribution valve 31 in such a way that the temperature detected by the temperature sensor 16 becomes the target temperature during the driving of the compressor 11.

[0090] In this manner, by controlling the first distributing valve 31 so that the detected temperature of the refrigerant R flowing into the expansion valve 13 reaches the target temperature, the amount of refrigerant R bypassing the second heat exchanger 12B is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the second heat exchanger 12B. Thus, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0091] (3) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a pressure sensor 17, which detects the pressure of the liquid refrigerant R flowing into the expansion valve 13; a first bypass line L11, which is connected to the refrigerant circulation line L9 so that the refrigerant R bypasses the second heat exchanger 12B for heat dissipation; and a first distribution valve 31, which adjusts the distribution amount of the refrigerant R supplied to the second heat exchanger 12B for heat dissipation and the refrigerant R supplied to the first bypass line L11. When the compressor 11 is driven, the control unit 100 calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor 17, and calculates the subcooling degree of the liquid refrigerant R by subtracting the temperature detected by the temperature sensor 16 from the condensing temperature, and controls the first distribution valve 31 in such a manner that the calculated subcooling degree becomes the target subcooling degree.

[0092] In this manner, by controlling the first distributing valve 31 so that the calculated degree of subcooling of the refrigerant R flowing into the expansion valve 13 reaches the target degree of subcooling, the amount of refrigerant R bypassing the second heat exchanger 12B for heat dissipation is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the second heat exchanger 12B for heat dissipation. Consequently, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0093] <Second embodiment>

[0094] Next, a second embodiment will be described with reference to the drawings. Figure 3 1 is a diagram schematically showing the configuration of the hot water supply system 1 according to the present embodiment. In this embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals and their description may be omitted.

[0095] like Figure 3 As shown, the heat pump circuit 10 of this embodiment does not include the first bypass line L11 and the first distribution valve 31 .

[0096] In the present embodiment, the refrigerant temperature sensor 16 , the second bypass line L12 , and the second distributing valve 32 constitute a refrigerant temperature adjustment unit 50 .

[0097] As described above, the second bypass line L12 is a line that allows the feed water W2 to bypass the second heat exchanger 12B for heat dissipation.

[0098] The second distribution valve 32 is a valve that adjusts the distribution amount of the makeup water W2 supplied to the second heat exchanger 12B and the second bypass line L12. The second distribution valve 32 of this embodiment is controlled by the distribution valve control unit 130 of the control unit 100.

[0099] The distribution valve control unit 130 of the present embodiment obtains the temperature detected by the refrigerant temperature sensor 16 and, based on the detected temperature, controls the valve opening of the second distribution valve 32 constituting the refrigerant temperature adjustment unit 50 of the present embodiment. Specifically, the distribution valve control unit 130 controls the second distribution valve 32 so that the temperature detected by the refrigerant temperature sensor 16 becomes the target temperature during the driving of the compressor 11. As a more specific control, for example, the following feedback control is preferably adopted: the refrigerant temperature detected in real time by the refrigerant temperature sensor 16 is used as a feedback value, and the valve opening of the second distribution valve 32 is adjusted so that the refrigerant temperature approaches the target temperature. In addition to proportional control (P control), feedback control can also adopt an operation algorithm that combines the operation amount of integral control (I control) and / or differential control (D control).

[0100] Thus, the amount of the makeup water W2 bypassing the second heat exchanger 12B for heat dissipation is adjusted, and the temperature of the liquid refrigerant R flowing into the expansion valve 13 is adjusted.

[0101] The above configuration allows the temperature of the liquid refrigerant R flowing into the expansion valve to be maintained at a constant temperature, preventing it from becoming excessively subcooled, even when the source temperature of the makeup water is low. This prevents the supply of highly subcooled liquid refrigerant R to the heat-absorbing heat exchanger 14, and prevents the compressor 11 from being hindered from sucking in wet vapor refrigerant R. This prevents damage to the compressor 11 and allows the refrigeration cycle to operate optimally.

[0102] Next, a modification of the second embodiment will be described with reference to the drawings. Figure 4 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the second embodiment.

[0103] like Figure 4 As shown, the heat pump circuit 10 of this modification includes a refrigerant pressure sensor 17 for detecting the pressure of the liquid refrigerant R flowing into the expansion valve 13, similarly to the modification of the first embodiment. Furthermore, the control unit 100 of this modification includes a subcooling degree calculation unit 140, similarly to the modification of the first embodiment.

[0104] In this modification, the refrigerant pressure sensor 17 , the refrigerant temperature sensor 16 , the second bypass line L12 , and the second distributing valve 32 constitute a refrigerant temperature adjustment unit 50 .

[0105] The distributing valve control unit 130 of this embodiment controls the second distributing valve 32 based on the temperature detected by the refrigerant temperature sensor 16 and the pressure detected by the refrigerant pressure sensor 17. Specifically, the distributing valve control unit 130 of this modified example controls the second distributing valve 32 so that the calculated subcooling degree calculated by the subcooling degree calculation unit 140 reaches the target subcooling degree, thereby adjusting the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13. In this case, feedback control is also preferably employed, using the calculated subcooling degree calculated in real time by the subcooling degree calculation unit 140 as a feedback value to adjust the valve opening of the second distributing valve 32 so that the calculated subcooling degree approaches the target subcooling degree.

[0106] In this manner, the subcooling degree calculation unit 140 accurately calculates the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13, and the distribution valve control unit 130 controls the second distribution valve 32 so that the calculated subcooling degree reaches the target subcooling degree. This adjusts the amount of makeup water W2 bypassing the second heat exchanger 12B, thereby suppressing the amount of cooling of the liquid refrigerant R in the second heat exchanger 12B. Consequently, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0107] It should be noted that in this embodiment, the second distributing valve 32 is not limited to being provided in the second bypass line L12. For example, the second distributing valve 32 may be a three-way valve provided at the branching portion where the second bypass line L12 branches from the feed water line L2.

[0108] According to the hot water supply system 1 of the second embodiment described above, in addition to (1), the following effects are achieved.

[0109] (4) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a second bypass line L12, which is connected to the feed water line L2, so that the feed water W2 bypasses the second heat exchanger 12B for heat dissipation; and a second distribution valve 32, which adjusts the distribution amount of the feed water W2 supplied to the second heat exchanger 12B for heat dissipation and the feed water W2 supplied to the second bypass line L12. The control unit 100 controls the second distribution valve 32 in such a way that the temperature detected by the temperature sensor 16 becomes the target temperature during the driving of the compressor 11.

[0110] In this manner, by controlling the second distribution valve 32 so that the detected temperature of the refrigerant R flowing into the expansion valve 13 reaches the target temperature, the amount of makeup water W2 bypassing the second heat exchanger 12B is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the second heat exchanger 12B. Thus, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0111] (5) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a pressure sensor 17, which detects the pressure of the liquid refrigerant R flowing into the expansion valve 13; a second bypass line L12, which is connected to the feed water line L2 so that the feed water W2 bypasses the second heat exchanger 12B for heat dissipation; and a second distribution valve 32, which adjusts the distribution amount of the feed water W2 supplied to the second heat exchanger 12B for heat dissipation and the feed water W2 supplied to the second bypass line L12. When the compressor 11 is driven, the control unit 100 calculates the condensation temperature of the gas refrigerant R based on the pressure detected by the pressure sensor 17, and calculates the subcooling degree of the liquid refrigerant R by subtracting the temperature detected by the temperature sensor 16 from the condensing temperature, and controls the second distribution valve 32 in such a manner that the calculated subcooling degree becomes the target subcooling degree.

[0112] In this manner, by controlling the second distributing valve 32 so that the calculated degree of subcooling of the refrigerant R flowing into the expansion valve 13 reaches the target degree of subcooling, the amount of makeup water W2 bypassing the second heat exchanger 12B is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the second heat exchanger 12B. Consequently, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0113] <Third embodiment>

[0114] Next, a third embodiment will be described with reference to the drawings. Figure 5 1 is a diagram schematically showing the configuration of the hot water supply system 1 according to the present embodiment. In this embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals and their description may be omitted.

[0115] like Figure 5 As shown, the heat pump circuit 10 of this embodiment does not include the first bypass line L11 and the first distribution valve 31. Instead, it includes a third bypass line L13 and a third distribution valve 33.

[0116] In the present embodiment, the refrigerant temperature sensor 16 , the third bypass line L13 , and the third distributing valve 33 constitute a refrigerant temperature adjustment unit 50 .

[0117] The third bypass line L13 is a line that allows the refrigerant R to bypass the first heat exchanger 12A for heat radiation.

[0118] The third distributing valve 33 is a valve that distributes the refrigerant R supplied to the first heat exchanger 12A and the refrigerant R supplied to the third bypass line L13 . The third distributing valve 33 of this embodiment is controlled by the distributing valve control unit 130 of the control unit 100 .

[0119] The distribution valve control unit 130 of the present embodiment obtains the temperature detected by the refrigerant temperature sensor 16 and, based on the detected temperature, controls the valve opening of the third distribution valve 33 constituting the refrigerant temperature adjustment unit 50 of the present embodiment. Specifically, the distribution valve control unit 130 controls the third distribution valve 33 so that the temperature detected by the refrigerant temperature sensor 16 reaches the target temperature during the operation of the compressor 11. As a more specific control, for example, the following feedback control is preferably adopted: using the refrigerant temperature detected in real time by the refrigerant temperature sensor 16 as a feedback value, the valve opening of the third distribution valve 33 is adjusted so that the refrigerant temperature approaches the target temperature. In addition to proportional control (P control), feedback control can also adopt a calculation algorithm that combines the operation amount of integral control (I control) and / or differential control (D control).

[0120] Thus, the amount of the refrigerant R bypassing the first heat exchanger 12A for heat radiation is adjusted, and the amount of cooling of the refrigerant R in the first heat exchanger 12A for heat radiation is suppressed.

[0121] Note that, as a result of the bypass, the refrigerant R that has not been condensed and liquefied in the first heat exchanger 12A for heat radiation is condensed and liquefied in the second heat exchanger 12B for heat radiation.

[0122] With the above configuration, even when the hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature, preventing it from becoming excessively subcooled. This prevents the supply of highly subcooled liquid refrigerant R to the heat-absorbing heat exchanger 14, and prevents the compressor 11 from being hindered from sucking in wet vapor refrigerant R. This prevents damage to the compressor 11 and allows the refrigeration cycle to operate optimally.

[0123] Next, a modification of the third embodiment will be described with reference to the drawings. Figure 6 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the third embodiment.

[0124] like Figure 6 As shown, the heat pump circuit 10 of this modification includes a refrigerant pressure sensor 17 for detecting the pressure of the liquid refrigerant R flowing into the expansion valve 13, similarly to the modification of the first embodiment. Furthermore, the control unit 100 of this modification includes a subcooling degree calculation unit 140, similarly to the modification of the first embodiment.

[0125] In this modification, the refrigerant pressure sensor 17 , the refrigerant temperature sensor 16 , the third bypass line L13 , and the third distributing valve 33 constitute a refrigerant temperature adjustment unit 50 .

[0126] The distributing valve control unit 130 of this embodiment controls the third distributing valve 33 based on the temperature detected by the refrigerant temperature sensor 16 and the pressure detected by the refrigerant pressure sensor 17. Specifically, the distributing valve control unit 130 of this modified example controls the third distributing valve 33 so that the calculated degree of subcooling calculated by the degree of subcooling calculation unit 140 reaches the target degree of subcooling, thereby adjusting the degree of subcooling of the liquid refrigerant R flowing into the expansion valve 13. In this case, feedback control is also preferably employed, using the calculated degree of subcooling calculated in real time by the degree of subcooling calculation unit 140 as a feedback value to adjust the valve opening of the third distributing valve 33 so that the calculated degree of subcooling approaches the target degree of subcooling.

[0127] In this way, the subcooling degree calculation unit 140 accurately calculates the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13, and the distribution valve control unit 130 controls the third distribution valve 33 so that the calculated subcooling degree reaches the target subcooling degree. This adjusts the amount of refrigerant R bypassing the first heat dissipation heat exchanger 12A, thereby suppressing the amount of cooling of the refrigerant R in the first heat dissipation heat exchanger 12A. As a result, even when the stored hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0128] Note that, in this embodiment, the third distributing valve 33 is not limited to being provided in the third bypass line L13. For example, the third distributing valve 33 may be a three-way valve provided at the branching portion where the third bypass line L13 branches from the refrigerant circulation line L9.

[0129] According to the water heating system 1 of the third embodiment described above, in addition to (1), the following effects are achieved.

[0130] (6) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a third bypass line L13, which is connected to the refrigerant circulation line L9, so that the refrigerant R bypasses the first heat exchanger 12A for heat dissipation; and a third distribution valve 33, which adjusts the distribution amount of the refrigerant R supplied to the first heat exchanger 12A for heat dissipation and the refrigerant R supplied to the third bypass line L13. The control unit 100 controls the third distribution valve 33 in such a way that the temperature detected by the temperature sensor 16 becomes the target temperature during the driving of the compressor 11.

[0131] In this manner, by controlling the third distributing valve 33 so that the detected temperature of the refrigerant R flowing into the expansion valve 13 reaches the target temperature, the amount of refrigerant R bypassing the first heat dissipation heat exchanger 12A is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the first heat dissipation heat exchanger 12A. Thus, even when the stored hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0132] (7) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a pressure sensor 17, which detects the pressure of the liquid refrigerant R flowing into the expansion valve 13; a third bypass line L13, which is connected to the refrigerant circulation line L9 so that the refrigerant R bypasses the first heat exchanger 12A for heat dissipation; and a third distribution valve 33, which adjusts the distribution amount of the refrigerant R supplied to the first heat exchanger 12A for heat dissipation and the refrigerant R supplied to the third bypass line L13. When the compressor 11 is driven, the control unit 100 calculates the condensation temperature of the gas refrigerant R based on the pressure detected by the pressure sensor 17, and calculates the subcooling degree of the liquid refrigerant R by subtracting the temperature detected by the temperature sensor 16 from the condensing temperature, and controls the third distribution valve 33 in such a way that the calculated subcooling degree becomes the target subcooling degree.

[0133] In this manner, by controlling the third distributing valve 33 so that the calculated degree of subcooling of the refrigerant R flowing into the expansion valve 13 reaches the target degree of subcooling, the amount of refrigerant R bypassing the first heat dissipation heat exchanger 12A is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the first heat dissipation heat exchanger 12A. Thus, even when the stored hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0134] <Fourth embodiment>

[0135] Next, a fourth embodiment will be described with reference to the drawings. Figure 7 1 is a diagram schematically showing the configuration of the hot water supply system 1 according to the present embodiment. In this embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0136] like Figure 7 As shown, the heat pump circuit 10 of this embodiment does not include the first bypass line L11 and the first distribution valve 31 , but includes a fourth bypass line L14 and a fourth distribution valve 34 instead.

[0137] In the present embodiment, the refrigerant temperature sensor 16 , the fourth bypass line L14 , and the fourth distributing valve 34 constitute a refrigerant temperature adjustment unit 50 .

[0138] The fourth bypass line L14 is a line that allows the circulating water W1 to bypass the first heat exchanger 12A for heat radiation.

[0139] The fourth distribution valve 34 is a valve that adjusts the distribution amount of the circulating water W1 supplied to the first heat exchanger 12A and the circulating water W1 supplied to the fourth bypass line L14. The fourth distribution valve 34 of this embodiment is controlled by the distribution valve control unit 130 of the control unit 100.

[0140] The distribution valve control unit 130 of the present embodiment obtains the temperature detected by the refrigerant temperature sensor 16 and, based on the detected temperature, performs control to adjust the valve opening of the fourth distribution valve 34 constituting the refrigerant temperature adjustment unit 50 of the present embodiment. Specifically, the distribution valve control unit 130 controls the fourth distribution valve 34 so that the temperature detected by the refrigerant temperature sensor 16 becomes the target temperature during the driving of the compressor 11. As a more specific control, for example, the following feedback control is preferably adopted: the refrigerant temperature detected in real time by the refrigerant temperature sensor 16 is used as a feedback value, and the valve opening of the fourth distribution valve 34 is adjusted so that the refrigerant temperature approaches the target temperature. In addition to proportional control (P control), feedback control can also adopt an operation algorithm that combines the operation amount of integral control (I control) and / or differential control (D control).

[0141] Thus, the amount of the circulating water W1 bypassing the first heat exchanger 12A for heat radiation is adjusted, and the temperature of the liquid refrigerant R flowing into the expansion valve 13 is adjusted.

[0142] Note that, as a result of the bypass, the refrigerant R that has not been condensed and liquefied in the first heat exchanger 12A for heat radiation is condensed and liquefied in the second heat exchanger 12B for heat radiation.

[0143] With the above configuration, even when the source temperature of the makeup water is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature, preventing it from becoming excessively subcooled. This prevents the supply of highly subcooled liquid refrigerant R to the heat-absorbing heat exchanger 14, and prevents the compressor 11 from hindrance to the intake of wet vapor refrigerant R. This prevents damage to the compressor 11 and allows the refrigeration cycle to operate optimally.

[0144] Next, a modification of the fourth embodiment will be described with reference to the drawings. Figure 8 It is a diagram schematically showing the configuration of a hot water supply system according to a modified example of the fourth embodiment.

[0145] like Figure 8 As shown, the heat pump circuit 10 of this modification includes a refrigerant pressure sensor 17 for detecting the pressure of the liquid refrigerant R flowing into the expansion valve 13, similarly to the modification of the first embodiment. Furthermore, the control unit 100 of this modification includes a subcooling degree calculation unit 140, similarly to the modification of the first embodiment.

[0146] In this modification, the refrigerant pressure sensor 17 , the refrigerant temperature sensor 16 , the fourth bypass line L14 , and the fourth distributing valve 34 constitute a refrigerant temperature adjustment unit 50 .

[0147] The distributing valve control unit 130 of this embodiment controls the fourth distributing valve 34 based on the temperature detected by the refrigerant temperature sensor 16 and the pressure detected by the refrigerant pressure sensor 17. Specifically, the distributing valve control unit 130 of this modified example controls the fourth distributing valve 34 so that the calculated degree of subcooling calculated by the degree of subcooling calculation unit 140 reaches the target degree of subcooling, thereby adjusting the degree of subcooling of the liquid refrigerant R flowing into the expansion valve 13. In this case, feedback control is also preferably employed, using the calculated degree of subcooling calculated in real time by the degree of subcooling calculation unit 140 as a feedback value to adjust the valve opening of the fourth distributing valve 34 so that the calculated degree of subcooling approaches the target degree of subcooling.

[0148] In this manner, the subcooling degree calculation unit 140 accurately calculates the subcooling degree of the liquid refrigerant R flowing into the expansion valve 13, and the distribution valve control unit 130 controls the fourth distribution valve 34 so that the calculated subcooling degree reaches the target subcooling degree. This adjusts the amount of makeup water W2 bypassing the first heat exchanger 12A, thereby suppressing the amount of cooling of the refrigerant R in the first heat exchanger 12A. Consequently, even when the source temperature of the makeup water W2 is low, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0149] Note that, in this embodiment, the fourth distributing valve 34 is not limited to being provided in the fourth bypass line L14. For example, the fourth distributing valve 34 may be a three-way valve provided at the branching portion of the fourth bypass line L14 from the water circulation line L1.

[0150] According to the water heating system 1 of the fourth embodiment described above, in addition to (1), the following effects are achieved.

[0151] (8) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a fourth bypass line L14, which is connected to the water circulation line L1 so that the circulating water W1 bypasses the first heat exchanger 12A for heat dissipation; and a fourth distribution valve 34, which adjusts the distribution amount of the circulating water W1 supplied to the first heat exchanger 12A for heat dissipation and the circulating water W1 supplied to the fourth bypass line L14. The control unit 100 controls the fourth distribution valve 34 in such a way that the temperature detected by the temperature sensor 16 becomes the target temperature during the driving of the compressor 11.

[0152] In this manner, by controlling the fourth distributing valve 34 so that the detected temperature of the liquid refrigerant R flowing into the expansion valve 13 reaches the target temperature, the amount of circulating water W1 bypassing the first heat exchanger 12A is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the first heat exchanger 12A. Thus, even when the stored hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0153] (9) The refrigerant temperature adjustment unit 50 of the hot water supply system 1 of this embodiment includes: a temperature sensor 16, which detects the temperature of the liquid refrigerant R flowing into the expansion valve 13; a pressure sensor 17, which detects the pressure of the liquid refrigerant R flowing into the expansion valve 13; a fourth bypass line L14, which is connected to the water circulation line L1 so that the circulating water W1 bypasses the first heat exchanger 12A for heat dissipation; and a fourth distribution valve 34, which adjusts the distribution amount of the circulating water W1 supplied to the first heat exchanger 12A for heat dissipation and the circulating water W1 supplied to the fourth bypass line L14. When the compressor 11 is driven, the control unit 100 calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor 17, and subtracts the temperature detected by the temperature sensor 16 from the condensation temperature to calculate the subcooling degree of the liquid refrigerant R, and controls the fourth distribution valve 34 in such a manner that the calculated subcooling degree becomes the target subcooling degree.

[0154] In this manner, by controlling the fourth distributing valve 34 so that the calculated degree of subcooling of the refrigerant R flowing into the expansion valve 13 reaches the target degree of subcooling, the amount of circulating water W1 bypassing the first heat exchanger 12A is adjusted, thereby suppressing the amount of cooling of the refrigerant R in the first heat exchanger 12A. Thus, even when the stored hot water temperature is set to a low temperature, the temperature of the liquid refrigerant R flowing into the expansion valve 13 can be maintained at a constant temperature that does not become excessively subcooled.

[0155] While preferred embodiments of the hot water supply system of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate. In addition, a plurality of embodiments can be combined.

[0156] Description of reference numerals:

[0157] 1...hot water supply system;

[0158] 10...heat pump circuit;

[0159] 11...Compressor;

[0160] 12A...first heat exchanger for heat dissipation (condenser);

[0161] 12B...second heat exchanger for heat dissipation (subcooler);

[0162] 13...Expansion valve;

[0163] 14...Heat exchanger (evaporator) for heat absorption;

[0164] 16...Refrigerant temperature sensor (temperature sensor);

[0165] 17...Refrigerant pressure sensor (pressure sensor);

[0166] 21...water circulation pump;

[0167] 22...first temperature sensor;

[0168] 25...Supply water valve;

[0169] 26...second temperature sensor;

[0170] 31...first distribution valve;

[0171] 32...second distribution valve;

[0172] 33...the third distributing valve;

[0173] 34...Fourth distribution valve;

[0174] 60...hot water storage tank;

[0175] 61...Hot water temperature sensor;

[0176] 62...water level sensor;

[0177] 100...control unit (control unit);

[0178] 110...water circulation pump control unit;

[0179] 120...Supply water valve control unit;

[0180] 130...distribution valve control unit;

[0181] 140...subcooling degree calculation unit;

[0182] L1...water circulation pipeline;

[0183] L2...Supply water line;

[0184] L4...hot water supply line;

[0185] L9...refrigerant circulation pipeline;

[0186] L11...first bypass line;

[0187] L12...second bypass line;

[0188] L13...third bypass line;

[0189] L14...fourth bypass line;

[0190] W1...circulating water;

[0191] W2...make-up water;

[0192] W3...Stored water;

[0193] W4...hot water supply;

[0194] R...Refrigerant (gas refrigerant, liquid refrigerant).

Claims

1. A hot water supply system, wherein: The hot water supply system comprises: A vapor compression heat pump circuit, wherein a compressor, a first heat dissipation heat exchanger, a second heat dissipation heat exchanger, an expansion valve, and a heat absorption heat exchanger are connected in a loop via a refrigerant circulation line, and heat energy is extracted by the first heat dissipation heat exchanger and / or the second heat dissipation heat exchanger by driving the compressor; a hot water storage tank for storing make-up water; a water circulation line for circulating the stored water in the hot water storage tank through the first heat exchanger for heat dissipation; a make-up water line for circulating make-up water through the second heat exchanger for heat dissipation and supplying make-up water to the hot water storage tank; a refrigerant temperature adjustment unit for adjusting the temperature of the liquid refrigerant flowing into the expansion valve; as well as a control unit for controlling the refrigerant temperature adjustment unit, The refrigerant temperature adjustment unit includes: a bypass line for allowing refrigerant or circulating water to bypass the first heat exchanger for heat dissipation, or for allowing refrigerant or feed water to bypass the second heat exchanger for heat dissipation; as well as A distribution valve adjusts the distribution amount of the refrigerant, circulating water or make-up water supplied to the bypass line.

2. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a first bypass line connected to the refrigerant circulation line to allow the refrigerant to bypass the second heat exchanger for heat dissipation; as well as a first distributing valve for adjusting the distribution amount of the refrigerant supplied to the second heat-radiating heat exchanger and the refrigerant supplied to the first bypass line; The control unit controls the first distribution valve so that the temperature detected by the temperature sensor becomes a target temperature during driving of the compressor.

3. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor for detecting the pressure of the liquid refrigerant flowing into the expansion valve; a first bypass line connected to the refrigerant circulation line to allow the refrigerant to bypass the second heat exchanger for heat dissipation; as well as a first distributing valve for adjusting the distribution amount of the refrigerant supplied to the second heat-radiating heat exchanger and the refrigerant supplied to the first bypass line; During the driving of the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the subcooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the first distributing valve in such a manner that the calculated subcooling degree becomes a target subcooling degree.

4. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a second bypass line connected to the feed water line so as to allow the feed water to bypass the second heat exchanger; as well as a second distributing valve for adjusting the distribution amount of the makeup water supplied to the second heat exchanger for heat dissipation and the makeup water supplied to the second bypass line; The control unit controls the second distributing valve so that the temperature detected by the temperature sensor becomes a target temperature during driving of the compressor.

5. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor for detecting the pressure of the liquid refrigerant flowing into the expansion valve; a second bypass line connected to the feed water line so as to allow the feed water to bypass the second heat exchanger; as well as a second distributing valve for adjusting the distribution amount of the makeup water supplied to the second heat exchanger for heat dissipation and the makeup water supplied to the second bypass line; During the driving of the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the subcooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the second distributing valve in such a manner that the calculated subcooling degree becomes a target subcooling degree.

6. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a third bypass line connected to the refrigerant circulation line to allow the refrigerant to bypass the first heat exchanger for heat dissipation; as well as a third distributing valve for adjusting the distribution amount of the refrigerant supplied to the first heat-radiating heat exchanger and the refrigerant supplied to the third bypass line; The control unit controls the third distributing valve so that the temperature detected by the temperature sensor becomes a target temperature during driving of the compressor.

7. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor for detecting the pressure of the liquid refrigerant flowing into the expansion valve; a third bypass line connected to the refrigerant circulation line to allow the refrigerant to bypass the first heat exchanger for heat dissipation; as well as a third distributing valve for adjusting the distribution amount of the refrigerant supplied to the first heat-radiating heat exchanger and the refrigerant supplied to the third bypass line; During the driving of the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the subcooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the third distributing valve in such a manner that the calculated subcooling degree becomes a target subcooling degree.

8. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a fourth bypass line connected to the water circulation line to allow circulating water to bypass the first heat exchanger; as well as a fourth distributing valve for adjusting the distribution amount of the circulating water supplied to the first heat exchanger for heat dissipation and the circulating water supplied to the fourth bypass line; The control unit controls the fourth distributing valve so that the temperature detected by the temperature sensor becomes a target temperature during driving of the compressor.

9. The hot water supply system according to claim 1, wherein: The refrigerant temperature adjustment unit comprises: a temperature sensor for detecting the temperature of the liquid refrigerant flowing into the expansion valve; a pressure sensor for detecting the pressure of the liquid refrigerant flowing into the expansion valve; a fourth bypass line connected to the water circulation line to allow circulating water to bypass the first heat exchanger; as well as a fourth distributing valve for adjusting the distribution amount of the circulating water supplied to the first heat exchanger for heat dissipation and the circulating water supplied to the fourth bypass line; During the driving of the compressor, the control unit calculates the condensation temperature of the gas refrigerant based on the pressure detected by the pressure sensor, and calculates the subcooling degree of the liquid refrigerant by subtracting the temperature detected by the temperature sensor from the condensing temperature, so as to control the fourth distributing valve in such a manner that the calculated subcooling degree becomes a target subcooling degree.

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