Water heating system

Abstract

The present invention provides a water supply heating system. Further efficiency improvement is sought in a water supply heating system that uses a heat pump circuit and a heat recovery heat exchanger at the same time. The water supply heating system comprises: a steam compression heat pump circuit, which connects a compressor, a condenser, an expansion valve, and an evaporator in a ring shape through a refrigerant circulation pipeline, and extracts heat in the condenser by driving the compressor; a heat recovery heat exchanger; a heat source fluid pipeline, which causes the heat source fluid to flow in the order of the heat recovery heat exchanger and the evaporator; a water supply pipeline, which causes the water supply to flow in the order of the heat recovery heat exchanger and the condenser; a refrigerant flow adjustment unit, which adjusts the refrigerant flow based on the superheat of the gas refrigerant flowing into the compressor; a water supply flow adjustment unit, which adjusts the water supply flow based on the outlet heated water temperature of the water supply flowing out of the condenser; and a control unit, which controls the refrigerant flow adjustment unit and the water supply flow adjustment unit.

Description

Technical Field

[0001] The present invention relates to a water supply heating system. Background Art

[0002] In recent years, efforts to effectively utilize unused heat from various equipment have been underway in factories and other business locations to reduce emissions of carbon dioxide, a greenhouse gas. Consequently, as shown in Patent Documents 1 and 2, proposed unused heat utilization systems (feedwater heating systems) have been proposed that reduce boiler fuel usage by heating boiler feedwater using a heat pump circuit using wastewater as a heat source.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-210118

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-169819 Summary of the Invention

[0007] The water supply heating systems described in Patent Documents 1 and 2 are not only suitable for heating boiler water supply, but can also be used for heating water used in various production processes. The system involved in Patent Document 1 is configured so that the heat source fluid (waste water) circulates in the order of the evaporator and the heat recovery heat exchanger, and the supply water (cold water) circulates in the order of the heat recovery heat exchanger, the subcooler, and the condenser. Due to this structure, the system involved in Patent Document 1 succeeds in making the COP (coefficient of performance: energy consumption efficiency) very high compared to the existing heat pump system without a heat recovery heat exchanger and a subcooler. On the other hand, the system has the following problem: if the temperature of the heat source fluid becomes relatively low (for example, below 40°C), the heat recovery heat exchanger becomes ineffective.

[0008] In contrast, the system described in Patent Document 2 is configured to circulate the heat source fluid (wastewater) sequentially through the heat recovery heat exchanger and evaporator. This structure prevents the heat recovery heat exchanger from maximizing its effectiveness if the heat source fluid temperature is higher than the supply water. While the system described in Patent Document 2 can recover heat from a wide range of heat source fluid temperatures with a high COP, further efficiency improvements are desired in locations facing ambitious CO2 emission reduction targets.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to further improve the efficiency of a water supply heating system that uses a heat pump circuit and a heat recovery heat exchanger simultaneously.

[0010] Means for solving problems

[0011] The present invention relates to a water supply heating system, comprising: a vapor compression heat pump circuit, in which a compressor, a condenser, an expansion valve and an evaporator are connected in a ring shape through a refrigerant circulation pipeline, and heat is extracted from the condenser by driving the compressor; a heat recovery heat exchanger; a heat source fluid pipeline, in which the heat source fluid flows in the order of the heat recovery heat exchanger and the evaporator; a water supply pipeline, in which the supply water flows in the order of the heat recovery heat exchanger and the condenser; a refrigerant flow adjustment unit, which is controlled based on the superheat of the gas refrigerant flowing into the compressor and adjusts the refrigerant flow; a water supply flow adjustment unit, which is controlled based on the outlet heated water temperature of the supply water flowing out of the condenser and adjusts the water supply flow; and a control unit, which controls the refrigerant flow adjustment unit and the water supply flow adjustment unit.

[0012] Furthermore, preferably, the heat source fluid pipeline has a connection structure in which the heat source fluid and the supply water exchange heat in countercurrent in the heat recovery heat exchanger and then exchange heat between the heat source fluid and the liquid refrigerant in countercurrent in the evaporator.

[0013] In addition, it is preferred that the device is provided with: an intake temperature sensor for detecting the intake temperature of the gas refrigerant flowing into the compressor; a vapor pressure sensor for detecting the vapor pressure of the gas refrigerant flowing out of the evaporator; and a hot water temperature sensor for detecting the hot water outlet temperature of the supply water flowing out of the condenser, the control unit obtains the evaporation temperature of the liquid refrigerant based on the detection pressure of the vapor pressure sensor, and calculates the superheat of the gas refrigerant by subtracting the evaporation temperature from the detection temperature of the intake temperature sensor, controls the refrigerant flow adjustment unit so that the calculated superheat becomes the target superheat, and controls the supply water flow adjustment unit so that the detection temperature of the hot water outlet temperature sensor becomes the target hot water outlet temperature.

[0014] Furthermore, it is preferable that a heat source temperature sensor is provided to detect the temperature of the heat source fluid before flowing into the evaporator, and the control unit sets the target superheat degree according to the temperature detected by the heat source temperature sensor.

[0015] Furthermore, it is preferable that the control unit increases the target degree of superheat when determining that the variation in the temperature detected by the heat source temperature sensor is large.

[0016] Furthermore, it is preferable that the control unit decrease the target superheat degree when determining that the temperature detected by the heat source temperature sensor is stable.

[0017] Furthermore, it is preferable that a supply water temperature sensor is provided to detect the temperature of the supply water before flowing into the condenser, and the control unit sets the target outlet heated water temperature according to the temperature detected by the supply water temperature sensor.

[0018] In addition, it is preferred to have: a water supply temperature sensor for detecting the temperature of the supply water before flowing into the condenser, and the target hot water outlet temperature can be set to a value between an upper limit value and a lower limit value, and the lower limit value is a value obtained by adding a given value to the detection temperature of the water supply temperature sensor, and the value is higher as the detection temperature of the water supply temperature sensor is higher.

[0019] In addition, it is preferred to have: 1 or 2 bypass pipelines, which allow the water supply to bypass the heat recovery heat exchanger and / or allow the heat source fluid to bypass the heat recovery heat exchanger; and a preheating mode switching unit, which switches the water supply preheating mode and the preheating stop mode, wherein in the water supply preheating mode, the water supply and the heat source fluid are simultaneously circulated to the heat recovery heat exchanger, and in the preheating stop mode, at least one of the water supply and the heat source fluid is circulated to the bypass pipeline.

[0020] In addition, it is preferred to have: a water supply temperature sensor before the heat exchanger flows into the heat exchanger, which detects the temperature of the water supply before flowing into the heat recovery heat exchanger; and a heat source temperature sensor before the heat exchanger flows into the heat recovery heat exchanger, which detects the temperature of the heat source fluid before flowing into the heat exchanger, the control unit compares the first detection temperature of the water supply temperature sensor before the heat exchanger flows into the heat exchanger and the second detection temperature of the heat source temperature sensor before the heat exchanger flows into the heat exchanger, and when the first detection temperature is lower than the second detection temperature, controls the preheating mode switching unit to execute the water supply preheating mode, and when the first detection temperature is higher than the second detection temperature, controls the preheating mode switching unit to execute the preheating stop mode.

[0021] In addition, preferably, the control unit has: a signal input unit that receives a preheating mode designation signal that specifies the category of the water supply preheating mode or the preheating stop mode; and a preheating mode switching control unit that controls the preheating mode switching unit according to the preheating mode designation signal input into the signal input unit so that the water supply preheating mode or the preheating stop mode is executed.

[0022] Effects of the Invention

[0023] According to the present invention, in a water supply heating system using both a heat pump circuit and a heat recovery heat exchanger, further improvement in efficiency can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a diagram schematically showing a water supply and heating system according to one embodiment of the present invention.

[0025] Figure 2 This is a block diagram showing the control unit of the above embodiment.

[0026] Figure 3 It is a graph showing the change in the temperature detected by the heat source temperature sensor.

[0027] Figure 4 This is a diagram showing the settable range of the target outlet heated water temperature in the above embodiment.

[0028] Figure 5 It is a Mollier diagram used to illustrate the heat pump cycle.

[0029] Figure 6A 3 is a state transition diagram of the water flow mode switching control in the above embodiment.

[0030] Figure 6B 1 is a flowchart showing the flow of a target superheat setting process in the above-described embodiment.

[0031] Figure 6C 1 is a flowchart showing the flow of preheating mode switching control in the above embodiment.

[0032] Figure 7 It is a diagram schematically showing a water supply and heating system according to a modified example of the above-mentioned embodiment.

[0033] Description of Reference Numerals

[0034] 1 Water supply heating system

[0035] 10 Heat pump circuit

[0036] 11 Compressor

[0037] 12 Condenser

[0038] 12A condenser

[0039] 12B subcooler

[0040] 13 Expansion valve (refrigerant flow adjustment unit)

[0041] 14 Evaporator

[0042] 17 Suction temperature sensor

[0043] 18 Steam pressure sensor

[0044] 21 Water supply pump (water supply flow adjustment unit, water flow mode switching unit)

[0045] 24 No. 1 water supply temperature sensor (water supply temperature sensor before heat exchanger inflow, water supply temperature sensor)

[0046] 25 Three-way valve (preheating mode switching unit)

[0047] 26 Second water supply temperature sensor (water supply temperature sensor)

[0048] 27 Outlet hot water temperature sensor

[0049] 31 Reflux pump (water supply flow adjustment unit, water flow mode switching unit)

[0050] 40 Heat exchanger for heat recovery

[0051] 50 heat source water tank

[0052] 53 Heat source supply pump

[0053] 54 1st heat source temperature sensor (heat source temperature sensor before heat exchanger inflow, heat source temperature sensor)

[0054] 55 Second heat source temperature sensor (heat source temperature sensor)

[0055] 60 hot water tank

[0056] 61 Hot water temperature sensor

[0057] 62 Water level detection unit

[0058] 63 Hot water supply pump

[0059] 70 water supply tank

[0060] 100 Control Department

[0061] 111 Target superheat setting unit

[0062] 112 Superheat calculation unit

[0063] 113 Refrigerant flow control unit

[0064] 121 Target hot water temperature setting range determination unit

[0065] 122 Target hot water temperature setting unit

[0066] 123 Water supply flow control unit

[0067] 130 Water flow mode switching control unit

[0068] 140 Preheating mode switching control unit

[0069] 150 signal input unit

[0070] 151 1st signal input unit

[0071] 152 Second signal input unit

[0072] L1 water supply line

[0073] L2 return line

[0074] L3 bypass line

[0075] L4 hot water supply line

[0076] L5 heat source fluid pipeline

[0077] L9 refrigerant circulation pipeline

[0078] R Refrigerant (gas refrigerant, liquid refrigerant)

[0079] W Make-up water

[0080] W1 Water Supply

[0081] W2 Hot water

[0082] W5 heat source water (heat source fluid) DETAILED DESCRIPTION

[0083] Hereinafter, a preferred embodiment of the water supply and heating system 1 of the present invention will be described with reference to the drawings. In this specification, the term "pipeline" is a general term for pipelines such as flow paths, pathways, and pipes through which fluid can flow.

[0084] Figure 1 Schematically shows the structure of the water supply and heating system 1 according to this embodiment. Figure 1 As shown, the feed water heating system 1 is a system that supplies feed water W1 heated by the heat recovery heat exchanger 40 and the heat pump circuit 10 as hot water W2 to a location requiring hot water.

[0085] In more detail, the water supply heating system 1 of this embodiment includes: a feed water tank 70 for storing feed water W to be used as feed water W1; a heat recovery heat exchanger 40 and a heat pump circuit 10 for heating the feed water W1; a hot water tank 60 for storing the heated feed water W1 as hot water W2; and a heat source water tank 50 for storing heat source water W5 as a heat source fluid.

[0086] In addition, the water supply heating system 1 of this embodiment includes: a water supply pipeline L1 that allows the supply water W1 to flow in the order of the heat recovery heat exchanger 40 and the condenser 12 of the heat pump circuit 10; a return pipeline L2 that allows the hot water W2 in the hot water tank 60 to flow back to the upstream side of the heat recovery heat exchanger 40; a bypass pipeline L3 that allows the supply water W1 to bypass the heat recovery heat exchanger 40; a hot water supply pipeline L4 for supplying the hot water W2 in the hot water tank 60 to a location where hot water is required; and a heat source fluid pipeline L5 that allows the heat source water W5 as a heat source fluid to flow to the heat recovery heat exchanger 40 and the evaporator 14 of the heat pump circuit 10.

[0087] The make-up water tank 70 is a tank for storing make-up water W used as feed water W1 heated by the heat recovery heat exchanger 40 and the heat pump circuit 10 , and is connected to a water supply line L1 .

[0088] The heat recovery heat exchanger 40 is an indirect heat exchanger that performs indirect heat exchange between the supply water W1 flowing through the water supply line L1 and the heat source water W5 flowing through the heat source fluid line L5. More specifically, the heat recovery heat exchanger 40 performs heat exchange between the supply water W1 before passing through the condenser 12 of the heat pump circuit 10 and the heat source water W5 before passing through the evaporator 14 of the heat pump circuit 10.

[0089] The supply water W1 of the water supply line L1 passes through the heat recovery heat exchanger 40 and the condenser 12 in this order, and the heat source water W5 of the heat source fluid line L5 passes through the heat recovery heat exchanger 40 and the evaporator 14 in this order.

[0090] The heat pump circuit 10 is a vapor compression heat pump circuit, with a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14 connected in a loop via a refrigerant circulation line L9. The compressor 11 is driven to extract heat in the condenser 12. Refrigerant R flows through the refrigerant circulation line L9.

[0091] The compressor 11 includes an electric motor 15 as a driving source, and compresses a gaseous refrigerant R, such as Freon gas, into a high-temperature, high-pressure refrigerant R. The condenser 12 releases heat to the supply water W1 fed through the water supply line L1, condensing and liquefying the refrigerant R from the compressor 11. The expansion valve 13 allows the refrigerant R fed from the condenser 12 to pass through, thereby reducing the pressure and temperature of the refrigerant R. The evaporator 14 absorbs heat from the heat source water W5 fed through the heat source fluid line L5, evaporating the refrigerant R fed from the expansion valve 13.

[0092] Thus, in the heat pump circuit 10, the refrigerant R absorbs heat from the outside and vaporizes in the evaporator 14, while the refrigerant R releases heat to the outside and condenses in the condenser 12. Using this principle, the heat pump circuit 10 absorbs heat from the heat source water W5 in the evaporator 14 and heats the supply water W1 in the water supply line L1 in the condenser 12.

[0093] The refrigerant circulation line L9 of the heat pump circuit is provided with a suction temperature sensor 17 for detecting the suction temperature of the gas refrigerant R flowing into the compressor 11 and a vapor pressure sensor 18 for detecting the vapor pressure of the gas refrigerant R flowing out of the evaporator 14 .

[0094] Here, the expansion valve 13 constitutes a refrigerant flow control unit that adjusts the flow rate of the refrigerant R flowing in the refrigerant circulation line L9 of the heat pump circuit 10. Specifically, the expansion valve 13 is configured as a proportional control needle valve, and the needle valve stroke can be changed by controlling the speed of the driving stepping motor, and the flow rate of the refrigerant R can be adjusted by adjusting the valve opening.

[0095] The hot water tank 60 is a tank that stores the feed water W1 heated by the heat recovery heat exchanger 40 and the heat pump circuit 10 as hot water W2.

[0096] The hot water W2 stored in the hot water tank 60 can be circulated and heated. Specifically, the hot water W2 in the hot water tank 60 can flow through the return line L2 to merge with the water supply line L1. The hot water W2 can then pass through the heat recovery heat exchanger 40 and the condenser 12 through the water supply line L1 to be heated and returned to the hot water tank 60.

[0097] Furthermore, the hot water tank 60 is provided with a hot water temperature sensor 61 for detecting the temperature of the hot water W2 in the hot water tank 60. Furthermore, the hot water tank 60 is provided with a water level detection unit 62 for detecting the water level in the hot water tank 60. In this embodiment, the water level detection unit 62 includes an electrode-type water level detector having a plurality of electrode rods. Specifically, two electrode rods 621 and 622 of different lengths are inserted and held at different heights of their lower ends. In this embodiment, the electrode rods 621 and 622 are inserted into the hot water tank 60 while sequentially lowering the heights of their lower ends. Each electrode rod 621 and 622 detects the presence or absence of water at its lower end by determining whether its lower end is immersed in water.

[0098] In this embodiment, the control unit 100 performs switching control of the water flow mode described later using detection results of the hot water temperature sensor 61 and the water level detection unit 62. The details of this control will be described later.

[0099] The heat source water tank 50 stores heat source water W5, which serves as the heat source fluid for the heat pump circuit 10. For example, waste water from a factory is used as heat source water W5. An overflow line (not shown) is provided in the heat source water tank 50 to allow the heat source water above a predetermined level to overflow. Furthermore, a water level detector (not shown) is provided in the heat source water tank 50 to monitor whether the heat source water level falls below a predetermined minimum level.

[0100] The water supply line L1 is connected on its upstream side to the makeup water tank 70 and on its downstream side to the hot water tank 60. Furthermore, arranged in this order, from the upstream side, on the water supply line L1 are a water supply pump 21, a first check valve 23, a first water supply temperature sensor 24, a three-way valve 25 arranged at a branching portion of the bypass line, a heat recovery heat exchanger 40, a second water supply temperature sensor 26, a condenser 12, and a hot water outlet temperature sensor 27.

[0101] The speed of the water supply pump 21 can be controlled by an inverter. By varying the speed of the water supply pump 21, the water flow rate flowing through the water supply line L1 to the hot water tank 60 in the single-pass water flow mode, described later, can be adjusted. In other words, the water supply pump 21 constitutes a water flow rate adjustment unit for the single-pass water flow mode.

[0102] The first check valve 23 is provided upstream of a junction of a return line L2 to be described later, thereby preventing the hot water W2 from flowing into the makeup water tank 70 during a water circulation mode to be described later.

[0103] The first supply water temperature sensor 24 is a pre-heat exchanger supply water temperature sensor that detects the temperature of the supply water W1 before it flows into the heat recovery heat exchanger 40. The first supply water temperature sensor 24 is provided upstream of the branch portion of the bypass line L3.

[0104] A three-way valve 25 is located at the branch point of the bypass line L3. This valve switches whether the feed water W1 bypasses the heat recovery heat exchanger 40, constituting a preheating mode switching unit. The bypass line L3 bypasses the feed water W1 bypassing the heat recovery heat exchanger 40.

[0105] The second water supply temperature sensor 26 detects the temperature of the water supply W1 before it flows into the condenser 12 of the heat pump circuit 10. The second water supply temperature sensor 26 is arranged upstream of the condenser 12, and in this embodiment, downstream of the heat recovery heat exchanger 40.

[0106] The outlet heated water temperature sensor 27 detects the outlet heated water temperature of the heated feed water W1 flowing out of the condenser 12 .

[0107] The return line L2 is connected to the hot water tank 60 at its upstream side and to the water supply line L1 at its downstream side. A return pump 31 (circulation pump 31) and a second check valve 33 are arranged in this order from the upstream side in the return line L2.

[0108] The return pump 31 can have its rotational speed controlled by an inverter. By varying the rotational speed of the return pump 31, the flow rate of water circulating through the return line L2 and the supply line L1 and returning to the hot water tank 60 in the water circulation mode (described later) can be adjusted. In other words, the return pump 31 constitutes the water flow rate adjustment unit used in the water circulation mode.

[0109] The second check valve 33 is provided in the return line L2 upstream of the confluence of the water supply line L1 and the return line L2 to prevent the makeup water W from the makeup water tank 70 from flowing into the hot water tank 60 in the one-way water flow mode described later.

[0110] By providing such a supply water line L1 and return water line L2, if the supply water pump 21 is operated while the return water pump 31 is stopped, the makeup water W from the makeup water tank 70 can be used as supply water W1, passing through the heat recovery heat exchanger 40 and the condenser 12 in that order, where it is heated, and then supplied to the hot water tank 60. This is referred to as a single-pass water flow mode. On the other hand, if the return water pump 31 is operated while the supply water pump 21 is stopped, the hot water W2 in the hot water tank 60 can be used as supply water W1, passing through the heat recovery heat exchanger 40 and the condenser 12 in that order, where it is reheated, and then returned to the hot water tank 60, thereby circulating the stored water in the hot water tank 60. This is referred to as a circulating water flow mode. Furthermore, if both the supply water pump 21 and the return water pump 31 are stopped, the water flow to the heat recovery heat exchanger 40 and the condenser 12 can be stopped. This is referred to as a water flow stop mode.

[0111] That is, in this embodiment, the water supply pump 21 and the return pump 31 constitute a water flow mode switching unit that switches the following modes: a one-way water flow mode in which the hot water W2 is passed to the condenser 12 without flowing to the return line L2; a circulating water flow mode in which the hot water W2 is passed to the condenser 12 while flowing to the return line L2; and a water flow stop mode in which the water flow to the condenser 12 is stopped.

[0112] Then, the hot water W2 in the hot water tank 60 is supplied to a location requiring hot water through the hot water supply line L4.

[0113] A hot water supply pump 63 is provided on the hot water supply line L4. As an example of a location requiring hot water, water supply utilization by a steam boiler is cited. However, the utilization destination of the hot water W2 is not limited to the steam boiler. For example, the hot water W2 produced by the water supply heating system 1 of the present embodiment can also be utilized in the washing of containers for food / beverages / medicines, pasteurization (sterilization of bottles), etc. In this case, the supply of hot water W2 in a high temperature range of about 60°C to 80°C is sometimes required at all times. According to the water supply heating system 1 of the present embodiment, in applications requiring the supply of hot water at a temperature always within such a given temperature range, for example, in a system that supplies only heated water W1 to the hot water tank 60 (a system that does not directly supply unheated make-up water to the hot water tank 60), the hot water can be heated particularly suitably and efficiently, and can be supplied while maintaining its temperature.

[0114] The heat source fluid line L5 is provided with a heat source supply pump 53 , a first heat source temperature sensor 54 , a heat recovery heat exchanger 40 , a second heat source temperature sensor 55 , and an evaporator 14 in this order from the upstream side.

[0115] By operating the heat source supply pump 53 , the heat source water W5 from the heat source water tank 50 can be circulated in this order through the heat recovery heat exchanger 40 and the evaporator 14 .

[0116] The first heat source temperature sensor 54 is a pre-heat exchanger heat source temperature sensor that detects the temperature of the heat source water W5 before it flows into the heat recovery heat exchanger. In this embodiment, the first heat source temperature sensor 54 is provided in the heat source fluid line L5, but the sensor may also be provided in the heat source water tank 50.

[0117] The second heat source temperature sensor 55 detects the temperature of the heat source fluid that exchanges heat with the refrigerant R in the evaporator 14. In this embodiment, the second heat source temperature sensor 55 detects the temperature of the heat source water W5 before it flows into the evaporator 14. The second heat source temperature sensor 55 is located upstream of the evaporator 14, and in this embodiment, downstream of the heat recovery heat exchanger 40.

[0118] As described above, the heat source fluid line L5 has a connection structure in which the heat source water W5 flows through the heat recovery heat exchanger 40 and the evaporator 14 in this order.

[0119] By allowing the heat source water W5 to flow to the heat recovery heat exchanger 40 first, the preheating capacity of the feed water W1 can be increased, thereby improving the heat output of the heat recovery heat exchanger 40. The higher the temperature of the heat source water W5, the greater the effect of improving the heat output.

[0120] In addition, if Figure 1As shown, the heat source fluid line L5 has a connection structure in which the heat source water W5 and the feed water W1 are heat-exchanged by counterflow in the heat recovery heat exchanger 40 , and then the heat source water W5 and the liquid refrigerant R are heat-exchanged by counterflow in the evaporator 14 .

[0121] In this way, the heat recovery amount can be maximized by flowing the heat source water W5 in the order of the heat recovery heat exchanger 40 and the evaporator 14 and flowing in the heat recovery heat exchanger 40 and the evaporator 14 in the countercurrent direction relative to the flow direction of the feed water W1.

[0122] Next, the control unit 100 of the water supply and heating system 1 according to the embodiment will be described. Figure 2 This is a block diagram of a control unit 100, which serves as the control unit of the water supply heating system 1 according to this embodiment. The control unit 100 includes a target superheat setting unit 111, a superheat calculation unit 112, a refrigerant flow rate control unit 113, a target outlet heated water temperature setting range determination unit 121, a target outlet heated water temperature setting unit 122, a water supply flow rate control unit 123, a water flow mode switching control unit 130, a preheating mode switching control unit 140, a signal input unit 150, and a storage unit 160.

[0123] The target superheat setting unit 111 obtains the temperature of the heat source water W5 (heat source fluid), detected by the second heat source temperature sensor 55 (heat source temperature sensor), and sets the target superheat according to the temperature detected by the second heat source temperature sensor 55. When the temperature of the heat source water W5 (heat source fluid) is low, the target superheat is set lower. This increases the circulation flow rate of the refrigerant R, and can increase the amount of heat recovered even from low-temperature heat source water W5.

[0124] Thus, by setting an appropriate target superheat according to the temperature of the heat source water W5 as the heat source fluid, damage to the compressor 11 due to liquid compression or poor lubrication can be prevented while increasing the amount of heat recovered in the evaporator 14 .

[0125] Furthermore, the target superheat degree setting unit 111 may perform control to increase the target superheat degree when determining that the fluctuation in the detected temperature of the second heat source temperature sensor 55 is large.

[0126] Figure 3 The vertical axis is the detected temperature T of the second heat source temperature sensor 55 and the horizontal axis is the time t, and the graph shows the change of the detected temperature of the second heat source temperature sensor 55. For example, Figure 3As shown, when the amount of change ΔT per unit time t0 of the temperature detected by the second heat source temperature sensor 55 exceeds a given threshold value ΔT0, it is determined that the change in the temperature detected by the second heat source temperature sensor 55 is large, and control is performed to increase the target superheat. For example, assuming ΔT0 = 5°C and t0 = 1min, when there is a change greater than 5°C / min, control is performed to increase the target superheat. In this case, for example, if the target superheat has been set to 5°C, the target superheat is set to 10°C. Figure 3 In the example, the decrease ΔT of the detected temperature T per unit time t0 is larger than the predetermined threshold ΔT0. Therefore, it is considered that the temperature of the heat source water W5 has suddenly changed, and the target superheat degree is changed to, for example, 10°C.

[0127] Thus, even when a situation in which a sudden change in the temperature of the heat source water W5 serving as the heat source fluid is detected, the heat pump circuit 10 can be driven stably.

[0128] For example, even when the temperature of the heat source water W5 drops rapidly due to a sudden change in temperature, the refrigerant R can be reliably vaporized in the evaporator 14 by setting the target superheat to a high value, thereby preventing damage to the compressor 11 due to liquid compression.

[0129] Furthermore, the target superheat degree setting unit 111 may perform control to reduce the target superheat degree when it is determined that the temperature detected by the second heat source temperature sensor 55 is stable.

[0130] For example, if the temperature T detected by the second heat source temperature sensor 55 remains within a predetermined temperature range for a predetermined period of time, the temperature detected by the second heat source temperature sensor 55 is determined to be stable. Alternatively, if the change ΔT in the detected temperature T per unit time t0 during a predetermined period of time is less than a predetermined threshold value ΔT0, the temperature detected by the second heat source temperature sensor 55 is determined to be stable. In this case, control is performed to reduce the target superheat. For example, if the target superheat has previously been set to 10°C, the target superheat is changed to, for example, 5°C.

[0131] Furthermore, by setting the lower limit of the target superheat to, for example, 5°C, damage to the compressor 11 due to liquid compression can be prevented. Furthermore, by setting the upper limit of the target superheat to, for example, 10°C, the circulation flow rate of the refrigerant R can be maintained above a predetermined flow rate, thereby preventing a decrease in the amount of heat recovery.

[0132] In this way, when the temperature of the heat source water W5 as the heat source fluid is stable, by setting the target superheat degree to a low value, the circulation flow rate of the refrigerant R can be increased, and the amount of heat recovered in the evaporator 14 can be increased.

[0133] In this embodiment, the temperature detected by the second heat source temperature sensor 55 is used as the heat source temperature sensor when setting the target superheat. However, the first heat source temperature sensor 54 may also be used as the heat source temperature sensor to detect the temperature of the heat source water W5 before it flows into the evaporator 14 (the pre-evaporator heat source temperature). Although not immediately before it flows into the evaporator 14, the first heat source temperature sensor 54 can indirectly detect the temperature of the heat source fluid that is exchanging heat with the refrigerant R in the evaporator 14, thereby confirming any sudden changes in the temperature of the heat source water W5. It is more preferable to use the second heat source temperature sensor 55 to measure the temperature of the heat source water W5 immediately before it flows into the evaporator 14.

[0134] The superheat degree calculation unit 112 calculates the superheat degree of the refrigerant R flowing into the compressor 11 .

[0135] Specifically, the superheat calculation unit 112 obtains the evaporation temperature of the liquid refrigerant R based on the pressure detected by the vapor pressure sensor 18 , and calculates the superheat of the gas refrigerant R by subtracting the evaporation temperature from the temperature detected by the suction temperature sensor 17 .

[0136] The refrigerant flow control unit 113 controls the refrigerant flow control unit to adjust the flow rate of the refrigerant R so that the calculated superheat (the calculated value of the superheat calculation unit 112) becomes the target superheat (the set value of the target superheat setting unit 111).

[0137] As a specific control, for example, feedback control is preferably employed in which the valve opening of the expansion valve 13 is adjusted using the calculated superheat calculated in real time by the superheat calculation unit 112 as a feedback value so that the calculated superheat converges to the target superheat. Feedback control can employ not only proportional control (P control) but also a calculation algorithm for the manipulated variable that combines this with integral control (I control) and / or differential control (D control).

[0138] In this way, by accurately calculating the superheat of the gas refrigerant R by the superheat calculation unit 112 and then controlling the refrigerant flow rate control unit 113 to maintain this value, the heat output of the condenser 12 to the supply water W1 is stabilized. As a result, the flow rate of the supply water W1 supplied as hot water after being heated is reduced to a small amount.

[0139] The target outlet heated water temperature setting range determination unit 121 obtains the temperature of the supply water W1 before it flows into the condenser 12 , as detected by the second supply water temperature sensor 26 , and determines the target outlet heated water temperature setting range according to the temperature detected by the second supply water temperature sensor 26 .

[0140] Figure 4This is a diagram showing a settable range of the target outlet heated water temperature determined according to the temperature detected by the second supply water temperature sensor 26 . Figure 4 The horizontal axis represents the temperature detected by the second supply water temperature sensor 26 (supply water temperature before the condenser flows in), and the vertical axis represents the corresponding target outlet heated water temperature.

[0141] In this embodiment, the settable range of the target outlet heated water temperature is defined by the triangular area indicated by the settable range A. Specifically, in this embodiment, the target outlet heated water temperature can be set between an upper limit and a lower limit. The lower limit is the value obtained by adding a predetermined value to the temperature detected by the second supply water temperature sensor 26, and increases as the temperature detected by the second supply water temperature sensor 26 increases. More specifically, the lower limit is the value obtained by adding 15°C to the temperature detected by the second supply water temperature sensor 26, while the upper limit is a fixed temperature, which in this embodiment is 75°C.

[0142] A given value (e.g., 15°C) for setting the lower limit is stored in the storage unit 160 described later. In this case, the given value is preferably set by external input, etc. Alternatively, a lower limit based on the given value may be stored in the storage unit 160.

[0143] In this way, by setting the area shown in the settable range A as the settable range of the target heated water temperature, the system will be controlled so that the temperature difference between the supply water W1 on the inlet side and the outlet side of the condenser 12 is sufficiently large, thereby preventing insufficient supercooling of the refrigerant R flowing through the heat pump circuit 10, and in the control of the water supply flow adjustment unit performed by the water supply flow control unit 123 described later, the excessive water supply flow of the water supply W1 can be suppressed.

[0144] Furthermore, even when the settable range of the target outlet heated water temperature is set to a quadrilateral region with fixed upper and lower limits, that is, even when the lower limit is fixed, as long as, for example, Figure 4 The range shown in the settable range B can prevent insufficient supercooling of the refrigerant R and suppress excessive flow rate of the supply water W1. However, in this case, the range of the allowable heat source water temperature and the settable range of the target outlet heated water temperature are narrowed.

[0145] Furthermore, when the target outlet heated water temperature is set to a temperature lower than the lower limit value indicated in the settable range A, for example, if the temperature detected by the second supply water temperature sensor 26 does not change much, the refrigerant R may be insufficiently supercooled.

[0146] use Figure 5 The Mollier line diagram (ph line diagram) shown is used to illustrate this.

[0147] The vertical axis of the Mollier diagram represents the refrigerant pressure (p), and the horizontal axis represents the refrigerant specific enthalpy (h). Furthermore, the Mollier diagram shows a saturated liquid line Y1 and a saturated vapor line Y2. This Mollier diagram can be used to characterize the state changes of the refrigerant R in the heat pump cycle. The refrigerant R becomes a subcooled liquid state (the state of the liquid refrigerant R) to the left of the saturated liquid line Y1, becomes a gas-liquid mixed state, or wet vapor, between the saturated liquid line Y1 and the saturated vapor line Y2, and becomes a superheated vapor state (the state of the gas refrigerant R) to the right of the saturated vapor line Y2.

[0148] exist Figure 5 The solid line shown by R (a→b→c→d) in FIG. 1 represents the transition of the state of the refrigerant R in the heat pump cycle in an appropriate state.

[0149] The gas refrigerant R in the superheated vapor state sucked by the compressor 11 is adiabatically compressed in the compressor 11 and becomes a gas refrigerant R in the superheated vapor state of high temperature and high pressure (a→b). Thereafter, it is condensed / supercooled in the condenser 12 and becomes a liquid refrigerant R in the supercooled liquid state (b→c). Further, it is adiabatically expanded through the expansion valve 13 and becomes a refrigerant R in the wet vapor state (c→d). Then, the refrigerant R in the wet vapor state is evaporated / heated in the evaporator 14 and becomes a gas refrigerant R in the superheated vapor state (d→a). In such a cycle, the refrigerant R circulates. In addition, if the details are described, Figure 5 In the process (b→c), the condenser 12 releases the latent heat and sensible heat of the gas refrigerant R, changes the gas refrigerant R into the liquid refrigerant R, and supercools the liquid refrigerant R.

[0150] Here, when the target outlet heated water temperature is set to a temperature lower than the lower limit value shown in the settable range A, since the temperature difference between the water supply W1 on the inlet side and the outlet side of the condenser 12 becomes smaller, the refrigerant R may not be fully condensed / supercooled (b→c') in the condenser 12. As a result, the position of "c'", which indicates the state of the refrigerant R after passing through the condenser 12, deviates to the right compared to the appropriate situation. That is, the refrigerant R in the state of "c'" becomes insufficiently supercooled. In addition, it is also possible that the refrigerant R cannot fully become a liquid refrigerant. In this case, it cannot be said that the operation can be performed with an appropriate heat pump cycle.

[0151] However, in this embodiment, since the lower limit is set to the value obtained by adding a given value to the temperature detected by the second water supply temperature sensor 26, the system is controlled so that the temperature difference between the water supply W1 at the inlet and outlet sides of the condenser 12 is at least greater than the given value, thus avoiding the above-mentioned problem. In other words, the heat pump cycle can be operated in an appropriate state.

[0152] The target outlet heated water temperature setting unit 122 sets the target outlet heated water temperature within the aforementioned target outlet heated water temperature settable range, based on the temperature detected by the second water supply temperature sensor 26. For example, within the aforementioned settable range A, any target outlet heated water temperature can be set based on the requirements of the hot water demanding location, etc.

[0153] Specifically, the target outlet heated water temperature setting unit 122 obtains the temperature detected by the second water supply temperature sensor 26 and sets the target outlet heated water temperature by adding a predetermined value to the obtained temperature detected by the second water supply temperature sensor 26, with the lower limit being a value that increases as the temperature detected by the second water supply temperature sensor 26 increases. This allows the heat pump cycle to operate in an appropriate state and broadens the setting range of the target outlet heated water temperature.

[0154] Alternatively, a configuration may be adopted in which a value obtained by adding a predetermined value to the temperature detected by the second supply water temperature sensor 26 is automatically set as the target outlet heated water temperature.

[0155] The water flow control unit 123 controls the water flow adjustment unit to adjust the flow rate of the water supply W1 so that the temperature detected by the hot water temperature sensor 27 reaches the target outlet hot water temperature (the setting value of the target outlet hot water temperature setting unit 122 ).

[0156] As a specific example, feedback control is preferably employed. The outlet heated water temperature, detected in real time by the outlet heated water temperature sensor 27, is used as a feedback value to adjust the drive frequency of the water supply pump 21 or the return pump 31 so that the outlet heated water temperature converges to the target outlet heated water temperature. In addition to proportional control (P control), feedback control can also employ a calculation algorithm that combines this with integral control (I control) and / or differential control (D control).

[0157] In the one-way water flow mode described later, the inverter-controlled water supply pump 21 constitutes the water supply flow rate adjustment unit, and in the circulating water flow mode, the inverter-controlled return pump 31 constitutes the water supply flow rate adjustment unit.

[0158] The water supply flow rate adjustment unit can also be configured in other ways. For example, if the water supply pump 21 and the return pump 31 are pumps that can only be turned on and off, a proportionally controlled flow rate adjustment valve can be installed downstream of each pump to serve as the water supply flow rate adjustment unit. Alternatively, a proportionally controlled flow rate adjustment valve can be installed downstream of the confluence of the supply and return lines L1 and L2 to serve as the water supply flow rate adjustment unit.

[0159] In addition, as a structure to replace the water supply pump 21 and the return pump 31, on the basis of setting an on-off valve on the water supply pipeline L1 and the return pipeline L2, or on the basis of setting a three-way valve at the confluence of the water supply pipeline L1 and the return pipeline L2, a pump capable of inverter control can be set on the downstream side of the confluence of the water supply pipeline L1 and the return pipeline L2, and this can be used as a water supply flow adjustment unit.

[0160] In this way, by setting an appropriate target outlet heated water temperature according to the temperature of the feed water W1 before flowing into the condenser 12 , insufficient supercooling in the condenser 12 , excessive feed water flow rate, and the like can be prevented.

[0161] Furthermore, by setting the lower limit of the settable target outlet heated water temperature range according to the temperature of the supply water W1 before it flows into the condenser 12, insufficient subcooling in the condenser 12 can be reliably prevented, and the amount of heat recovered in the evaporator 14 can be stabilized. Furthermore, an excessive flow rate of the supply water W1 can be prevented, thereby suppressing degradation of the water supply pump 21 and other components due to overloading.

[0162] In this embodiment, the temperature detected by the second water supply temperature sensor 26 is used to set the target outlet heated water temperature. However, the first water supply temperature sensor 24 may also be used as a water supply temperature sensor to indirectly detect the temperature of the water supply W1 before it flows into the condenser 12 (the pre-condenser supply water temperature). However, for more stable control, it is preferable to use the second water supply temperature sensor 26 to measure the temperature of the water supply W1 immediately before it flows into the condenser 12.

[0163] As described so far, the water supply heating system 1 of the present embodiment circulates the heat source water W5 in the order of the heat recovery heat exchanger 40 and the evaporator 14. Furthermore, the water supply heating system 1 of the present embodiment is provided with a refrigerant flow rate adjustment unit that is controlled based on the superheat of the gas refrigerant R flowing into the compressor 11 and adjusts the refrigerant flow rate. In addition, it is provided with a water supply flow rate adjustment unit that is controlled based on the outlet heated water temperature of the supply water W1 flowing out of the condenser 12 and adjusts the water supply flow rate. Furthermore, the control unit 100 is provided with: a refrigerant flow rate control unit 113 that controls the refrigerant flow rate adjustment unit; and a water supply flow rate control unit 123 that controls the water supply flow rate adjustment unit.

[0164] Thus, by causing the heat source water W5 to flow to the heat recovery heat exchanger 40 first, the heat output of the heat recovery heat exchanger 40 is increased, and the preheating capacity of the supply water W1 is increased. Furthermore, the higher the heat source water temperature, the greater the effect of increasing heat output. If the amount of heat recovered by the heat recovery heat exchanger 40 is increased, the amount of heat recovered by the heat pump circuit 10 can be relatively reduced. In other words, while achieving the same system heat output as when the heat source water W5 flows sequentially through the evaporator 14 and the heat recovery heat exchanger 40, the compressor output can be reduced, thereby reducing the power consumption of the heat pump circuit 10.

[0165] At this time, although the temperature of the heat source water W5 flowing into the evaporator 14 will be reduced due to the fact that the heat source water W5 flows to the heat recovery heat exchanger 40 first, the COP of the system can be greatly improved in the structure in which the heat source water W5 flows to the heat recovery heat exchanger 40 first by utilizing multiple effects, wherein the multiple effects are brought about by adding further control, that is, the multiple effects brought about by the combination of adjustment of the refrigerant flow rate based on superheat and adjustment of the water supply flow rate based on the outlet hot water temperature, for example, the multiple effects of increased heat input to the evaporator 14 brought about by the adjustment of the refrigerant flow rate corresponding to the low superheat setting and further increased heat output of the heat recovery heat exchanger 40 brought about by the adjustment of the water supply flow rate corresponding to the low outlet hot water temperature setting, as well as the increased heat output of the evaporator 14.

[0166] The water flow mode switching control unit 130 performs water flow mode switching control to switch between a one-way water flow mode, a circulating water flow mode, and a water flow stop mode. More specifically, the water flow mode switching control unit 130 controls the water supply pump 21 and the return pump 31, which serve as water flow mode switching means, to switch between a one-way water flow mode in which hot water W2 is not passed to the return line L2 but is passed to the condenser 12, a circulating water flow mode in which hot water W2 is passed to the return line L2 and is passed to the condenser 12 simultaneously, and a water flow stop mode in which water flow to the condenser 12 is stopped.

[0167] Furthermore, in the water-flow mode, the return pump 31 is stopped, while the water supply pump 21 is driven, and the heat source supply pump 53 and the compressor 11 of the heat pump circuit 10 are driven. In the water-circulation mode, the water supply pump 21 is stopped, while the return pump 31 is driven, and the heat source supply pump 53 and the compressor 11 of the heat pump circuit 10 are driven. In the water-flow stop mode, the water supply pump 21 and the return pump 31 are stopped, and the compressor 11 of the heat pump circuit 10 is also stopped. Furthermore, it is preferable that the heat source supply pump 53 is also stopped.

[0168] In this embodiment, the water supply pump 21 and the return pump 31 constitute the water flow mode switching unit. However, the water flow mode switching unit may also be configured in other forms. For example, the water flow mode switching unit may be formed by a three-way valve located at the confluence of the supply line L1 and the return line L2, and a water supply pump located downstream of the confluence of the supply line L1 and the return line L2. In this case, the water flow mode is switched by switching the three-way valve and turning the water supply pump on and off.

[0169] By enabling operation in a circulating water flow mode in addition to the single-pass water flow mode, the hot water tank 60 can be circulated and heated as needed to maintain the stored hot water temperature. Furthermore, in the circulating water flow mode, the stored water in the hot water tank 60 is directed to flow immediately before the heat recovery heat exchanger 40 using the return line L2. Therefore, when the temperature of the heat source water W5 is higher than that of the hot water W2 stored in the hot water tank 60, the hot water W2 flowing as the supply water W1 is not only heated by the condenser 12 but also heated by the heat recovery heat exchanger 40 beforehand. This allows for efficient heating.

[0170] Here, the water flow mode switching control unit 130 controls the water supply to the hot water tank 60 and can also control the switching of the water flow mode based on the temperature of the hot water W2 in the hot water tank 60 .

[0171] Specifically, when new water supply is executed to the confluence part of the return pipeline L2, the water flow mode switching control unit 130 controls the water flow mode switching unit to execute the one-way water flow mode and stop the new water supply to the confluence part. When the detection temperature of the hot water temperature sensor 61 is lower than the given set temperature, the water flow mode switching unit is controlled to execute the circulation water flow mode and stop the new water supply to the confluence part. When the detection temperature of the hot water temperature sensor 61 is higher than the given set temperature, the water flow mode switching unit is controlled to execute the water flow stop mode.

[0172] Regarding the water flow mode switching control, use Figure 6A The state transition diagram shown is explained in detail.

[0173] During each water flow mode, the water flow mode switching control unit 130 monitors the water level of the hot water W2 in the hot water tank 60 via the water level detection unit 62 and the temperature of the hot water W2 in the hot water tank 60 via the hot water temperature sensor 61. During the water flow stop mode, if the water level exceeds the detection position of the electrode rod 622 of the water level detection unit 62 and the temperature detected by the hot water temperature sensor 61 exceeds the first set temperature (for example, a temperature 2 to 3°C lower than the target hot water outlet temperature), the water flow mode switching control unit 130 continues the water flow stop mode.

[0174] <Event E1>

[0175] During the water flow stop mode, if the water level in the hot water tank 60 drops below the detection position of the electrode rod 622 of the water level detector 62, the water flow mode switching control unit 130 drives the water supply pump 21 while the return pump 31 is stopped. This operation of the water supply pump 21 supplies new makeup water W to the confluence of the return line L2. Consequently, the water flow mode switching control unit 130 drives the heat source supply pump 53 and the compressor 11, shifting to the single-pass water flow mode. In the single-pass water flow mode, hot water W2 adjusted to a predetermined target outlet water temperature is supplied to the hot water tank 60.

[0176] <Event E2>

[0177] During the one-pass water flow mode, if the water level in the hot water tank 60 rises above the detection position of the electrode rod 621 of the water level detector 62, the water flow mode switching control unit 130 stops the water supply pump 21 while the return pump 31 is stopped. This stops the supply of new makeup water W to the confluence of the return line L2. Consequently, the water flow mode switching control unit 130 stops the heat source supply pump 53 and the compressor 11, transitioning to the water flow stop mode. In the water flow stop mode, the supply of hot water W2 to the hot water tank 60 is stopped.

[0178] <Event E3>

[0179] During the water supply stop mode, if the temperature detected by the hot water temperature sensor 61 is lower than the set temperature, the return pump 31 is driven while the supply water pump 21 remains stopped. This operation of the return pump 31 circulates the stored water while stopping the supply of new make-up water W to the confluence of the return line L2. Consequently, the water supply mode switching control unit 130 drives the heat source supply pump 53 and compressor 11 to shift to the circulating water supply mode. In the circulating water supply mode, hot water W2, reheated to a predetermined target outlet water temperature, is supplied to the hot water tank 60.

[0180] <Event E4>

[0181] During the water circulation mode, if the temperature detected by the hot water temperature sensor 61 exceeds the set temperature, the water flow mode switching control unit 130 stops the return pump 31 while maintaining the water supply pump 21 at rest. The heat source supply pump 53 and the compressor 11 are then stopped, transitioning to the water flow stop mode. In the water flow stop mode, the circulation of hot water W2 to the hot water tank 60 is stopped.

[0182] <Event E5>

[0183] During the circulation mode, if the water level in the hot water tank 60 drops below the detection position of the electrode rod 622 of the water level detector 62, the water mode switching control unit 130 stops the return pump 31 and activates the water supply pump 21. This operation of the water supply pump 21 supplies new makeup water W to the confluence of the return line L2. Consequently, the water mode switching control unit 130 switches to the single-pass mode while maintaining the operation of the heat source supply pump 53 and the compressor 11. In the single-pass mode, hot water W2 adjusted to a predetermined target outlet water temperature is supplied to the hot water tank 60.

[0184] In this embodiment, the system does not transition from single-pass water flow mode to circulating water flow mode. This is because the system transitions to single-pass water flow mode when demand for hot water is high, prioritizing the supply of makeup water W to the hot water tank 60 and rapidly restoring the water level. Furthermore, the outlet hot water temperature in single-pass water flow mode is higher than the stored hot water temperature in the hot water tank 60, allowing the stored hot water temperature to rise quickly.

[0185] The set temperature for determining whether to continue the water stop mode and the set temperature for determining whether to switch from the water stop mode to the circulating water mode may be the same or different. If they are different, the set temperature for the latter is set lower than the set temperature for the former.

[0186] In addition, when performing the switching control of the water flow mode, it is possible to determine whether to supply new water such as makeup water W to the confluence portion of the return line L2 based on the driving state of the water supply pump 21 (driving instruction signal or driving feedback signal).

[0187] Alternatively, a flow rate sensor (not shown) may be disposed upstream of the confluence point of the return line L2 in the water supply line L1 and determination may be made based on the detection result of the flow rate sensor.

[0188] According to follow Figure 6A The mode switching control shown in the state transition diagram allows operation in the single-pass water flow mode, which maximizes the system COP, when hot water demand is high and makeup water W is required. Furthermore, when hot water demand is low and makeup water W is not required, the temperature of the stored water in the hot water tank 60 can be raised in the circulating water flow mode as the temperature decreases. Furthermore, when hot water demand is low and makeup water W is not required, the system can enter standby mode in the water flow stop mode as long as the temperature of the stored water in the hot water tank 60 does not substantially decrease.

[0189] With the above-described structure, hot water W2 at a set temperature or higher can be always ensured in the hot water tank 60. In addition, the circulating water mode is executed only when the temperature of the stored water in the hot water tank 60 drops, so there is no unnecessary power consumption due to excessive water circulation.

[0190] The preheating mode switching control unit 140 performs preheating mode switching control to switch between a water supply preheating mode and a preheating stop mode. More specifically, the preheating mode switching control unit 140 controls the three-way valve 25, which serves as the preheating mode switching unit, to switch between a water supply preheating mode, in which both the supply water W1 and the heat source water W5 flow simultaneously to the heat recovery heat exchanger 40, and a preheating stop mode, in which the supply water W1 flows to the bypass line L3.

[0191] In this embodiment, the three-way valve 25 constitutes the preheating mode switching unit, but the preheating mode switching unit may also be configured in other forms. For example, two-way valves may be provided upstream of the confluence of the water supply line L1 with the bypass line L3 and in the bypass line L3, respectively, to form the preheating mode switching unit.

[0192] The bypass line is not limited to the one that bypasses the heat recovery heat exchanger 40. The heat source water W5 may also be bypassed to bypass the heat recovery heat exchanger 40. In this case, the heat source water W5 is allowed to flow through the bypass line in the preheating stop mode.

[0193] That is, it is provided with one or two bypass pipelines for bypassing the supply water W1 relative to the heat recovery heat exchanger 40 and / or for bypassing the heat source water W5 relative to the heat recovery heat exchanger 40, and the preheating mode switching unit only needs to be a form that switches between a water supply preheating mode in which the supply water W1 and the heat source water W5 are simultaneously circulated to the heat recovery heat exchanger 40 and a preheating stop mode in which at least one of the supply water W1 and the heat source water W5 is circulated to the bypass pipeline.

[0194] Thereby, the heat recovery heat exchanger 40 can be selectively used according to the situation.

[0195] Here, the preheating mode switching control unit 140 obtains the first detection temperature (water supply temperature before heat exchanger inflow) of the first water supply temperature sensor 24 (water supply temperature sensor 24 before heat exchanger inflow) for detecting the temperature of the supply water W1 before flowing into the heat recovery heat exchanger 40 and the second detection temperature (heat source temperature before heat exchanger inflow) of the first heat source temperature sensor 54 (heat source temperature sensor 54 before heat exchanger inflow) for detecting the temperature of the heat source water W5 before flowing into the heat recovery heat exchanger 40, and can perform switching control of the preheating mode based on the first detection temperature and the second detection temperature.

[0196] Specifically, the preheating mode switching control unit 140 compares the first detection temperature of the first water supply temperature sensor 24 and the second detection temperature of the first heat source temperature sensor 54. When the first detection temperature is lower than the second detection temperature, the preheating mode switching unit is controlled to execute the water supply preheating mode. When the first detection temperature is higher than the second detection temperature, the preheating mode switching unit is controlled to execute the preheating stop mode.

[0197] By automatically switching the preheating mode in accordance with the supply water temperature and the heat source water temperature, the system COP can be maximized.

[0198] Furthermore, the preheating mode switching control unit 140 can switch the preheating mode switching unit between the preheating modes at least when the water flow mode is the circulating water flow mode. In this case, the preheating mode switching control unit 140 can set the preheating mode switching unit to the preheating mode when the water flow mode is the single-pass water flow mode, and set the preheating mode switching unit to the preheating stop mode when the water flow mode is the water stop mode.

[0199] Thus, for example, in a one-way water flow mode in which the make-up water W, which is mostly at a relatively low temperature, is used as the supply water W1, the heat recovery heat exchanger can be actively and effectively utilized. On the other hand, in a circulating water flow mode in which the stored water in the hot water tank 60, which is mostly at a relatively high temperature, is used as the supply water W1, the heat recovery heat exchanger can be selectively and effectively utilized according to the relationship between the temperatures of the supply water W1 and the heat source water W5.

[0200] Among them, in order to achieve high-efficiency heating under various conditions of feed water temperature and heat source water temperature, the preheating mode switching control unit 140 can be configured to enable the preheating mode switching unit to switch between various preheating modes when the water flow mode is a circulating water flow mode or a one-way water flow mode.

[0201] The signal input unit 150 includes a first signal input unit 151 that receives a water flow mode designation signal for designating any one of the one-way water flow mode, the circulating water flow mode, and the water flow stop mode.

[0202] The water flow mode switching control unit 130 controls the water flow mode switching unit to execute the water flow mode, the circulating water flow mode, or the water flow stop mode according to the water flow mode designation signal input to the first signal input unit 151. Furthermore, when executing the circulating water flow mode or the water flow stop mode, the water flow mode switching control unit 130 controls the water supply pump 21 and other devices to stop the new water supply to the confluence point of the return line L2.

[0203] Thus, for example, an external signal with makeup water can be used to operate in a one-way water flow mode with the maximum system COP. In addition, an external signal without makeup water can be used to keep the stored water warm in a circulating water flow mode.

[0204] The signal input unit 150 further includes a second signal input unit 152 for receiving a preheating mode designation signal for designating either the water supply preheating mode or the preheating stop mode.

[0205] The preheating mode switching control unit 140 controls the preheating mode switching means according to the preheating mode designation signal input to the second signal input unit 152 so as to execute the water supply preheating mode or the preheating stop mode.

[0206] Thus, by switching the passive warm-up mode according to an external signal, it is possible to maximize the system COP.

[0207] The storage unit 160 stores various information necessary for control, such as various threshold values.

[0208] Next, an example of a control flow performed by the control unit 100 according to this embodiment will be described.

[0209] Figure 6B 1 is a flowchart showing an example of the flow of a target superheat setting process performed by the target superheat setting unit 111 of the control unit 100 .

[0210] First, when the system is started, the target superheat setting unit 111 sets the target superheat to a high temperature, for example, 10° C., in step S1 .

[0211] Next, in step S2, it is determined whether the temperature detected by the second heat source temperature sensor 55 is stable and is below a given heat source temperature threshold (for example, 60°C). Figure 3 ) and is below the predetermined heat source temperature threshold (step S2: YES), in step S3, the target superheat degree is set to a small value, for example, 5°C. On the other hand, if it is determined that the temperature detected by the second heat source temperature sensor 55 is unstable, or if it is determined that the temperature exceeds the predetermined heat source temperature threshold (step S2: NO), the process returns to step S1 and the target superheat degree is continued to be maintained at 10°C.

[0212] After the target superheat degree is set to 5°C in step S3, in step S4, it is determined whether the variation of the temperature detected by the second heat source temperature sensor 55 is large or exceeds a predetermined heat source temperature threshold. Figure 3), or if it is determined that the temperature exceeds the predetermined heat source temperature threshold (step S4: Yes), in step S5, the target superheat degree is increased, for example, to 10°C. On the other hand, if it is determined that the temperature detected by the second heat source temperature sensor 55 does not fluctuate significantly and is below the predetermined heat source temperature threshold (step S4: No), the process returns to step S3 and the target superheat degree is continued to be maintained at 5°C.

[0213] Thus, even when a situation in which a sudden change in the temperature of the heat source water W5 serving as the heat source fluid is detected, the heat pump circuit 10 can be driven stably.

[0214] Next, the preheating mode switching control is described. Figure 6A ).

[0215] Figure 6C This flowchart illustrates an example of a preheating mode switching control process for switching between a water supply preheating mode and a preheating stop mode, performed by the preheating mode switching control unit 140 of the control unit 100. In this example, the preheating mode switching control unit 140 performs preheating mode switching control based on the detection results of the first temperature detected by the first water supply temperature sensor 24 (the water supply temperature sensor before the heat exchanger flows in) (the water supply temperature before the heat exchanger flows in) and the second temperature detected by the first heat source temperature sensor 54 (the heat source temperature sensor before the heat exchanger flows in) (the heat source temperature before the heat exchanger flows in).

[0216] In step S11, the preheating mode switching control unit 140 determines whether the circulating water mode is being executed. If the circulating water mode is being executed (step S21: Yes), in step S12, the first detected temperature of the first water supply temperature sensor 24 is compared with the second detected temperature of the first heat source temperature sensor 54. If the first detected temperature is lower than the second detected temperature (step S12: Yes), in step S13, the water supply preheating mode is executed. On the other hand, if the first detected temperature is not lower than the second detected temperature (step S12: No), in step S14, the preheating stop mode is executed.

[0217] In addition, in step S11, it is determined whether the single-pass water flow mode or the circulating water flow mode is being executed. If the single-pass water flow mode or the circulating water flow mode is being executed, the control may be transferred to step S12.

[0218] Figure 7 It is a diagram schematically showing a modified example of the water supply and heating system 1 according to the first embodiment.

[0219] The condenser 12 of the heat pump circuit 10 in this embodiment is responsible for the condensation and supercooling of the refrigerant R. However, as shown in this modified example, the condenser of the heat pump circuit 10 can also be divided into a condenser 12A that mainly performs the function of condensing the refrigerant R and a subcooler 12B that mainly performs the function of supercooling the refrigerant R. In this case, the refrigerant R of the heat pump circuit 10 appropriately releases latent heat in the condenser 12A and releases sensible heat in the subcooler 12B. That is, in the condenser 12A, the gas refrigerant R condenses to become liquid refrigerant R, and the liquid refrigerant R is supplied to the subcooler 12B, and in the subcooler 12B, the liquid refrigerant R is further cooled (supercooled).

[0220] The subcooler 12B is an indirect heat exchanger that performs heat exchange between the supply water W1 supplied to the condenser 12A and the refrigerant R flowing from the condenser 12A to the expansion valve 13. The subcooler 12B allows the supply water W1 supplied to the condenser 12A to be used to subcool the refrigerant R flowing from the condenser 12A to the expansion valve 13, and allows the refrigerant R flowing from the condenser 12A to the expansion valve 13 to be used to heat the supply water W1 supplied to the condenser 12A.

[0221] In this way, by separating the heat exchanger for condensing the refrigerant R and for supercooling the refrigerant R, the design of the heat exchanger can be simplified, and the cost can be reduced. In addition, a general-purpose heat exchanger can also be used.

[0222] In this modification, the second water supply temperature sensor 26 as a water supply temperature sensor for detecting the temperature of the water supply W1 before flowing into the condenser 12 of the heat pump circuit 10 is preferably disposed upstream of the subcooler 12B.

[0223] Furthermore, if the hot water demanding portion is a steam boiler, for example, and the temperature of the hot water W2 in the hot water tank 60 can be allowed to drop to a certain extent, a makeup water line (not shown) may be provided to allow water to be supplied directly from the makeup water tank 70 to the hot water tank 60 without passing through the heat recovery heat exchanger 40 and the heat pump circuit 10. In this case, when the water level of the hot water W2 in the hot water tank 60 drops below the detection position of the electrode rod longer than the electrode rod 622, the makeup water pump provided in the makeup water line can be driven to supply makeup water W directly from the makeup water tank 70 to the hot water tank 60.

[0224] In this embodiment, heat source water W5 is used as the heat source fluid of the heat pump circuit 10. However, the heat source fluid is not limited to heat source water W5, and various fluids such as air and exhaust gas can be used. The heat source fluid is preferably a fluid that provides heat (sensible heat) to the supply water W1 in the heat recovery heat exchanger 40 while its own temperature decreases, and provides heat (sensible heat) to the refrigerant R of the heat pump circuit 10 in the evaporator 14 while its own temperature decreases.

[0225] Furthermore, the drive source for compressor 11 of heat pump circuit 10 is not limited to an electric motor. For example, compressor 11 may be driven by a steam motor using steam-generated power, or by an internal combustion engine. In this case, the output of compressor 11 and the refrigerant flow rate can be adjusted by adjusting the steam supply to the steam motor and the gas supply to the internal combustion engine.

[0226] According to the water supply and heating system 1 of the first embodiment described above, the following effects (1A) to (11A) can be achieved.

[0227] (1A) The water supply heating system 1 of this embodiment comprises: a vapor compression type heat pump circuit 10, which connects the compressor 11, the condenser 12, the expansion valve 13 and the evaporator 14 in a ring shape through the refrigerant circulation pipeline L9, and extracts heat from the condenser 12 by driving the compressor 11; a heat recovery heat exchanger 40; a heat source fluid pipeline L5, which allows the heat source fluid to flow in the order of the heat recovery heat exchanger 40 and the evaporator 14; a water supply pipeline L1, which allows the supply water W1 to flow in the order of the heat recovery heat exchanger 40 and the condenser 12; a refrigerant flow adjustment unit, which is controlled based on the superheat of the gas refrigerant R flowing into the compressor 11 and adjusts the refrigerant flow; a water supply flow adjustment unit, which is controlled based on the outlet hot water temperature of the supply water W1 flowing out of the condenser 12 and adjusts the water supply flow; and a control unit, which controls the refrigerant flow adjustment unit and the water supply flow adjustment unit.

[0228] In this way, by allowing heat source water W5, serving as the heat source fluid, to flow first to the heat recovery heat exchanger 40, the heat output of the heat recovery heat exchanger 40 is increased, and the preheating capacity of the supply water W1 is increased. The higher the heat source water temperature, the greater the effect of increasing heat output. Since the amount of heat recovered by the heat recovery heat exchanger 40 increases, the amount of heat recovered by the heat pump circuit 10 can be relatively reduced. While achieving the same system heat output as when heat source water W5 flows through the evaporator 14 and the heat recovery heat exchanger 40 in that order, the output of the compressor 11 can be reduced, thereby reducing the power consumption of the heat pump circuit 10.

[0229] At this time, by making the heat source water W5 flow to the heat recovery heat exchanger 40 first, the temperature of the heat source water W5 flowing into the evaporator 14 will be reduced, but in the structure of making the heat source water W5 flow to the heat recovery heat exchanger 40 first by utilizing multiple effects, the COP of the system can be greatly improved, wherein the multiple effects are brought about by adding further control, that is, the multiple effects brought about by the combination of adjustment of the refrigerant flow rate based on superheat and adjustment of the water supply flow rate based on the outlet hot water temperature, for example, the heat input of the evaporator 14 is increased by adjusting the refrigerant flow rate corresponding to the low superheat setting, the further heat output of the heat recovery heat exchanger 40 is increased by adjusting the water supply flow rate corresponding to the low outlet hot water temperature setting, and the heat output of the evaporator 14 is increased.

[0230] (2A) The heat source fluid pipeline L5 of the water supply heating system 1 of this embodiment has the following connection structure: after the heat source fluid and the supply water W1 are heat exchanged by countercurrent in the heat recovery heat exchanger 40, the heat source fluid and the liquid refrigerant R are heat exchanged by countercurrent in the evaporator 14.

[0231] In this way, the heat recovery amount can be maximized by flowing the heat source water W5 in the order of the heat recovery heat exchanger 40 and the evaporator 14 and flowing in the heat recovery heat exchanger 40 and the evaporator 14 in the countercurrent direction relative to the flow direction of the feed water W1.

[0232] (3A) The water supply heating system 1 of this embodiment comprises: an intake temperature sensor 17 for detecting the intake temperature of the gas refrigerant R flowing into the compressor 11; a steam pressure sensor 18 for detecting the steam pressure of the gas refrigerant R flowing out of the evaporator 14; and a hot water outlet temperature sensor 27 for detecting the outlet hot water temperature of the supply water W1 flowing out of the condenser 12. The control unit obtains the evaporation temperature of the liquid refrigerant R based on the detection pressure of the steam pressure sensor 18, and calculates the superheat of the gas refrigerant R by subtracting the evaporation temperature from the detection temperature of the intake temperature sensor 17. The refrigerant flow adjustment unit is controlled so that the calculated superheat becomes the target superheat, and the water supply flow adjustment unit is controlled so that the detection temperature obtained by the hot water temperature sensor 27 becomes the target outlet hot water temperature.

[0233] By accurately calculating the superheat of the gas refrigerant R and maintaining that value constant, the heat output of the condenser 12 to the preheated feed water W1 is stabilized. This reduces fluctuations in the hot water flow rate. Furthermore, by appropriately increasing the feed water flow rate, for example, using the set value of the target outlet hot water temperature, and maintaining that flow rate within a constant range, a high heat output can be maintained.

[0234] (4A) The water supply heating system 1 of this embodiment includes a heat source temperature sensor that detects the temperature of the heat source fluid before flowing into the evaporator 14, and the control unit sets the target superheat according to the temperature detected by the heat source temperature sensor.

[0235] In this way, by setting an appropriate target superheat degree according to the temperature of the heat source fluid, it is possible to increase the amount of heat recovered in the evaporator 14 while preventing damage to the compressor 11 due to liquid compression.

[0236] For example, when the heat source water temperature is low, setting a low target superheat increases the refrigerant circulation flow rate. This increases the heat recovery rate even with low-temperature heat source water W5. Setting the lower limit of the target superheat to, for example, 5°C prevents damage to the compressor 11 caused by liquid compression. Furthermore, setting the upper limit of the target superheat to, for example, 10°C maintains the refrigerant circulation flow rate above a predetermined level, preventing a decrease in heat recovery.

[0237] (5A) The control unit of the water supply heating system 1 of the present embodiment increases the target degree of superheat when determining that the fluctuation in the temperature detected by the heat source temperature sensor is large.

[0238] Thus, even when a situation in which a sudden change in the temperature of the heat source fluid is confirmed, the heat pump circuit 10 can be driven stably.

[0239] For example, even when the temperature of the heat source fluid drops rapidly, the refrigerant can be reliably vaporized in the evaporator 14 by setting the target superheat to a high value, thereby preventing damage to the compressor 11 due to liquid compression.

[0240] (6A) The control unit of the water supply heating system 1 of the present embodiment reduces the target degree of superheat when determining that the temperature detected by the heat source temperature sensor is stable.

[0241] Thus, when the temperature of the heat source fluid is stable, the target superheat degree is set to a low value to increase the refrigerant circulation flow rate, thereby increasing the amount of heat recovered in the evaporator 14 .

[0242] (7A) The water supply heating system 1 of this embodiment includes a water supply temperature sensor that detects the temperature of the water supply before flowing into the condenser 12 , and a control unit that sets a target outlet heated water temperature according to the temperature detected by the water supply temperature sensor.

[0243] In this way, by setting an appropriate target outlet heated water temperature according to the supply water temperature, it is possible to prevent insufficient supercooling, excessive supply water flow rate, and the like from occurring in the condenser 12 .

[0244] (8A) The water supply heating system 1 of this embodiment includes: a water supply temperature sensor for detecting the temperature of the supply water before flowing into the condenser 12, and the target hot water outlet temperature can be set to a value between an upper limit value and a lower limit value. The lower limit value is a value obtained by adding a given value to the detection temperature of the water supply temperature sensor, and the lower limit value is a higher value as the detection temperature of the water supply temperature sensor is higher.

[0245] By thus setting the lower limit of the settable target outlet heated water temperature range according to the supply water temperature, insufficient subcooling in the condenser 12 can be reliably prevented, stabilizing the amount of heat recovered in the evaporator 14. Furthermore, the supply water flow rate can be prevented from becoming excessive, thereby suppressing degradation of the water supply pump 21 due to overloading.

[0246] (9A) The water supply heating system 1 of this embodiment comprises: one or two bypass lines for bypassing the water supply W1 relative to the heat recovery heat exchanger 40 and / or for bypassing the heat source fluid relative to the heat recovery heat exchanger 40; and a preheating mode switching unit for switching between a water supply preheating mode for simultaneously flowing the water supply W1 and the heat source fluid to the heat recovery heat exchanger 40 and a preheating stop mode for flowing at least one of the water supply W1 and the heat source fluid to the bypass line.

[0247] Thus, by bypassing the heat recovery heat exchanger 40 when the heat recovery heat exchanger 40 cannot function effectively, the pressure loss of the feed water W1 and / or the heat source water W5 can be reduced, thereby improving the system COP including the feed water pump 21 and the heat source supply pump 53.

[0248] (10A) The water supply heating system 1 of this embodiment comprises: a water supply temperature sensor 24 before the heat exchanger flows in, which detects the temperature of the supply water W1 before flowing into the heat recovery heat exchanger 40; and a heat source temperature sensor 54 before the heat exchanger flows in, which detects the temperature of the heat source fluid before flowing into the heat recovery heat exchanger 40. The control unit compares the first detection temperature of the water supply temperature sensor 24 before the heat exchanger flows in, and the second detection temperature of the heat source temperature sensor 54 before the heat exchanger flows in. When the first detection temperature is lower than the second detection temperature, the preheating mode switching unit is controlled to execute the water supply preheating mode. When the first detection temperature is higher than the second detection temperature, the preheating mode switching unit is controlled to execute the preheating stop mode.

[0249] By automatically switching the preheating mode in accordance with the supply water temperature and the heat source water temperature, the system COP can be maximized.

[0250] (11A) The control unit of the water supply heating system 1 of this embodiment includes: a signal input unit 150, which receives a preheating mode designation signal that specifies the category of the water supply preheating mode or the preheating stop mode; and a preheating mode switching control unit 140, which controls the preheating mode switching unit according to the preheating mode designation signal input to the signal input unit 150, so that the water supply preheating mode or the preheating stop mode is executed.

[0251] By switching the passive warm-up mode according to such an external signal, the system COP can be maximized.

[0252] Furthermore, according to the water supply and heating system 1 of the first embodiment described above, the following effects (1B) to (8B) can also be achieved.

[0253] (1B) The water supply heating system 1 of this embodiment comprises: a vapor compression type heat pump circuit 10, which connects a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 in a ring shape through a refrigerant circulation line L9, and extracts heat from the condenser 12 by driving the compressor 11; a heat recovery heat exchanger 40; a heat source fluid line L5, which circulates the heat source fluid to the heat recovery heat exchanger 40 and the evaporator 14; a water supply line L1, which circulates the supply water W1 in the order of the heat recovery heat exchanger 40 and the condenser 12; and a hot water supply line L2. The tank 60 stores the hot water W2 generated in the condenser 12; the return line L2 allows the hot water W2 in the hot water tank 60 to flow back to the upstream side of the heat recovery heat exchanger 40; a water flow mode switching unit switches between a one-way water flow mode in which the hot water W2 is passed to the condenser 12 without flowing to the return line L2, a circulating water flow mode in which the hot water W2 is passed to the condenser 12 while flowing to the return line L2, and a water flow stop mode in which the water flow to the condenser 12 is stopped; and a control unit controls the water flow mode switching unit.

[0254] Thus, by being able to operate in a circulating water flow mode in addition to the single-pass water flow mode, the hot water tank 60 can be circulated and heated as needed to maintain the stored hot water temperature. In the circulating water flow mode, the stored water flows into the heat exchanger 40 immediately before the heat recovery heat exchanger 40, so when the stored water temperature is lower than the heat source water temperature, efficient heating can be achieved.

[0255] (2B) The water supply heating system 1 of this embodiment comprises: one or two bypass lines for bypassing the water supply W1 relative to the heat recovery heat exchanger 40 and / or for bypassing the heat source fluid relative to the heat recovery heat exchanger 40; and a preheating mode switching unit for switching between a water supply preheating mode for simultaneously flowing the water supply W1 and the heat source fluid to the heat recovery heat exchanger 40 and a preheating stop mode for flowing at least one of the water supply W1 and the heat source fluid to the bypass line.

[0256] This allows the heat recovery heat exchanger 40 to be selectively used according to the situation.

[0257] (3B) The control unit of the water supply and heating system 1 of the present embodiment can switch the preheating mode switching unit between the water supply preheating mode and the preheating stop mode at least in the water circulation mode.

[0258] Thus, for example, the heat recovery heat exchanger 40 can be actively and effectively utilized in the one-pass water flow mode, and the heat recovery heat exchanger 40 can be selectively and effectively utilized in the circulating water flow mode.

[0259] (4B) The heat source fluid line L5 of the water supply heating system 1 of the present embodiment has a connection structure that allows the heat source fluid to flow through the heat recovery heat exchanger 40 and the evaporator 14 in this order.

[0260] Thus, by allowing the heat source water W5 as the heat source fluid to flow to the heat recovery heat exchanger 40 first, the preheating amount of the feed water W1 can be increased, thereby improving the heat output of the heat recovery heat exchanger 40. The higher the heat source water temperature, the greater the effect of improving the heat output.

[0261] (5B) The water supply and heating system 1 of this embodiment comprises: a hot water temperature sensor 61 for detecting the temperature of the hot water W2 in the hot water tank 60; a control unit for controlling the water flow mode switching unit to execute a control-through water flow mode when a new water supply is executed to the confluence portion of the return line L2; controlling the water flow mode switching unit to execute a control-through water flow mode when a new water supply to the confluence portion is stopped and the temperature detected by the hot water temperature sensor 61 is lower than a set temperature; and controlling the water flow mode switching unit to execute a control-water flow stop mode when a new water supply to the confluence portion is stopped and the temperature detected by the hot water temperature sensor 61 is higher than a set temperature.

[0262] Thus, when the demand for hot water is high and the supply of makeup water W is necessary, the system COP can be maximized by operating in the single-pass water flow mode. Furthermore, when the demand for hot water is low and the supply of makeup water W is not necessary, the temperature of the stored water in the hot water tank 60 can be raised in the circulating water flow mode when the temperature drops.

[0263] (6B) The water supply heating system 1 of this embodiment comprises: a water supply temperature sensor 24 before the heat exchanger flows in, which detects the temperature of the supply water W1 before flowing into the heat recovery heat exchanger 40; and a heat source temperature sensor 54 before the heat exchanger flows in, which detects the temperature of the heat source fluid before flowing into the heat recovery heat exchanger 40. The control unit compares the first detection temperature of the water supply temperature sensor 24 before the heat exchanger flows in, and the second detection temperature of the heat source temperature sensor 54 before the heat exchanger flows in. When the first detection temperature is lower than the second detection temperature, the preheating mode switching unit is controlled to execute the water supply preheating mode. When the first detection temperature is higher than the second detection temperature, the preheating mode switching unit is controlled to execute the preheating stop mode.

[0264] By automatically switching the preheating mode in accordance with the supply water temperature and the heat source water temperature, the system COP can be maximized.

[0265] (7B) The control unit of the water supply and heating system 1 of this embodiment includes: a first signal input unit 151, which receives a water flow mode designation signal that designates any one of a water flow mode, a circulating water flow mode, and a water flow stop mode; and a water flow mode switching control unit 130, which controls the water flow mode switching unit according to the water flow mode designation signal input to the first signal input unit 151, so that a water flow mode, a circulating water flow mode, or a water flow stop mode is executed. When the circulating water flow mode or the water flow stop mode is executed, the water flow mode switching control unit 130 stops the new water supply to the confluence part of the return pipeline L2.

[0266] Thus, for example, an external signal indicating the supply of makeup water can be used to operate the system in a single-pass flow mode where the system COP is maximized. Furthermore, an external signal indicating the non-supply of makeup water can be used to keep the stored water warm in a circulation mode.

[0267] (8B) The control unit of the water supply heating system 1 of this embodiment includes: a second signal input unit 152, which receives a preheating mode designation signal that designates either a water supply preheating mode or a preheating stop mode; and a preheating mode switching control unit 140, which controls the preheating mode switching unit to execute the water supply preheating mode or the preheating stop mode according to the preheating mode designation signal input to the second signal input unit 152.

[0268] This makes it possible to switch the passive warm-up mode according to an external signal, for example, and maximize the system COP.

[0269] Furthermore, according to the water supply and heating system 1 of the first embodiment described above, the following effects (1C) to (7C) can also be achieved.

[0270] (1C) The water supply heating system 1 of this embodiment comprises: a steam compression heat pump circuit 10, which connects the compressor 11, the condenser 12, the expansion valve 13 and the evaporator 14 in a ring shape through the refrigerant circulation pipeline L9, and extracts heat in the condenser 12 by driving the compressor 11; a refrigerant flow adjustment unit, which adjusts the flow of the refrigerant R flowing through the heat pump circuit 10; a heat source temperature sensor, which detects the temperature of the heat source fluid that exchanges heat with the refrigerant R in the evaporator 14; and a control unit, which controls the refrigerant flow adjustment unit, and the control unit sets the target superheat corresponding to the detected temperature of the heat source temperature sensor, and controls the refrigerant flow adjustment unit so that the superheat of the refrigerant R flowing into the compressor 11 becomes the target superheat.

[0271] By setting an appropriate target superheat degree according to the temperature of the heat source fluid in this manner, it is possible to increase the amount of heat recovered in the evaporator 14 while preventing damage to the compressor 11 due to liquid compression.

[0272] For example, when the heat source water temperature is low, setting a low target superheat increases the refrigerant circulation flow rate. This increases the amount of heat recovery even when the heat source fluid is low-temperature heat source water W5. Setting the lower limit of the target superheat to, for example, 5°C prevents damage to the compressor 11 caused by liquid compression. Furthermore, setting the upper limit of the target superheat to, for example, 10°C maintains the refrigerant circulation flow rate above a predetermined level, preventing a decrease in heat recovery.

[0273] (2C) The control unit of the water supply heating system 1 of the present embodiment increases the target degree of superheat when determining that the fluctuation in the temperature detected by the heat source temperature sensor is large.

[0274] Thus, even when a situation in which a sudden change in the temperature of the heat source fluid is confirmed, the heat pump circuit 10 can be driven stably.

[0275] For example, even when the temperature of the heat source fluid drops rapidly, the refrigerant can be reliably vaporized in the evaporator 14 by setting the target superheat to a high value, thereby preventing damage to the compressor 11 due to liquid compression.

[0276] (3C) The control unit of the water supply and heating system 1 of the present embodiment reduces the target degree of superheat when determining that the temperature detected by the heat source temperature sensor is stable.

[0277] Thus, when the temperature of the heat source fluid is stable, the target superheat degree is set to a low value to increase the refrigerant circulation flow rate and thereby increase the amount of heat recovered in the evaporator 14 .

[0278] (4C) The water supply heating system 1 of this embodiment comprises: an intake temperature sensor 17 for detecting the intake temperature of the gas refrigerant R flowing into the compressor 11; and a steam pressure sensor 18 for detecting the steam pressure of the gas refrigerant R flowing out of the evaporator 14. The control unit obtains the evaporation temperature of the liquid refrigerant R based on the pressure detected by the steam pressure sensor 18, and calculates the superheat of the gas refrigerant R by subtracting the evaporation temperature from the temperature detected by the intake temperature sensor 17, and controls the refrigerant flow rate adjustment unit so that the calculated superheat becomes the target superheat.

[0279] By accurately calculating the degree of superheat of the gas refrigerant R and maintaining this value constant, the heat output of the condenser 12 to the preheated feed water W1 is stabilized. This reduces fluctuations in the hot water flow rate.

[0280] (5C) The water supply heating system 1 of this embodiment includes: a water supply flow rate adjustment unit for adjusting the water supply flow rate flowing through the condenser 12; and a hot water outlet temperature sensor 27 for detecting the hot water outlet temperature of the water supply W1 flowing out of the condenser 12. The control unit controls the water supply flow rate adjustment unit so that the temperature detected by the hot water temperature sensor 27 becomes the target hot water outlet temperature.

[0281] Thereby, the feed water W1 can be heated to a desired temperature at all times and hot water can be discharged.

[0282] (6C) The water supply heating system 1 of this embodiment includes a water supply temperature sensor that detects the temperature of the water supply W1 before flowing into the condenser 12, and the control unit sets the target outlet heated water temperature according to the temperature detected by the water supply temperature sensor.

[0283] In this way, by setting an appropriate target outlet heated water temperature according to the temperature of the feed water W1 , it is possible to prevent insufficient supercooling in the condenser 12 , excessive feed water flow rate, and the like from occurring.

[0284] (7C) The water supply heating system 1 of this embodiment includes: a water supply temperature sensor for detecting the temperature of the supply water W1 before it flows into the condenser 12, and the target hot water outlet temperature can be set to a value between an upper limit value and a lower limit value. The lower limit value is a value obtained by adding a given value to the detection temperature of the water supply temperature sensor, and the lower limit value is a higher value as the detection temperature of the water supply temperature sensor is higher.

[0285] By setting the lower limit of the settable target outlet heated water temperature range in accordance with the supply water temperature, insufficient subcooling in the condenser 12 can be reliably prevented, stabilizing the amount of heat recovered in the evaporator 14. Furthermore, excessive supply water flow can be prevented, thereby suppressing degradation of the water supply pump 21 due to overloading.

[0286] As mentioned above, the preferred embodiment of the water supply and heating system of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be modified as appropriate.

Claims

1. A water supply heating system comprising: A vapor compression heat pump circuit connects the compressor, condenser, expansion valve, and evaporator in a circular manner through a refrigerant circulation pipeline, and extracts heat from the condenser through the drive of the compressor; heat exchangers for heat recovery; a heat source fluid pipeline for circulating the heat source fluid in the order of the heat recovery heat exchanger and the evaporator; a water supply line for circulating water in the order of the heat recovery heat exchanger and the condenser; The water supply pump or flow regulating valve is a water supply flow regulating unit installed in the water supply pipeline. The speed of the water supply pump can be controlled by an inverter, and the flow regulating valve can be proportionally controlled. a suction temperature sensor for detecting the suction temperature of the gas refrigerant flowing into the compressor; a vapor pressure sensor for detecting the vapor pressure of the gas refrigerant flowing out of the evaporator; an outlet hot water temperature sensor for detecting the outlet hot water temperature of the supply water flowing out of the condenser; as well as A control unit controls the expansion valve and the water supply flow adjustment unit, The control unit is configured to adjust the valve opening of the expansion valve by feedback control during the driving of the compressor, and simultaneously adjust the driving frequency of the water supply pump or the valve opening of the flow regulating valve by feedback control. In the feedback control of the valve opening of the expansion valve, the control unit obtains the evaporation temperature of the liquid refrigerant based on the pressure detected by the vapor pressure sensor, and subtracts the evaporation temperature from the temperature detected by the suction temperature sensor to calculate the superheat of the gas refrigerant as a feedback value. The operation amount of the expansion valve is calculated using a PID calculation algorithm so that the calculated superheat becomes the target superheat. In the feedback control of the driving frequency of the water supply pump or the valve opening of the flow regulating valve, the control unit uses the temperature detected by the outlet heated water temperature sensor as a feedback value and calculates the operation amount of the water supply pump or the flow regulating valve using a PID calculation algorithm so that the detected temperature becomes a target outlet heated water temperature. The target outlet heated water temperature can be set to a value between an upper limit value and a lower limit value, wherein the lower limit value is a value obtained by adding a given value to the temperature of the supply water after flowing out of the heat recovery heat exchanger and before flowing into the condenser, so that the refrigerant flowing into the expansion valve becomes a supercooled liquid state.

2. The water supply heating system according to claim 1, wherein: The heat source fluid pipeline has a connection structure in which the heat source fluid and the supply water exchange heat in countercurrent in the heat recovery heat exchanger and then exchange heat between the heat source fluid and the liquid refrigerant in countercurrent in the evaporator.

3. The water supply heating system according to claim 1, wherein: The water supply heating system comprises: The heat source temperature sensor detects the temperature of the heat source fluid before flowing into the evaporator. The control unit sets the target superheat degree corresponding to the detected temperature of the heat source temperature sensor.

4. The water supply heating system according to claim 3, wherein: The control unit increases the target superheat degree when it is determined that the variation in the temperature detected by the heat source temperature sensor is large.

5. The water supply heating system according to claim 3, wherein: The control unit reduces the target superheat degree when it is determined that the temperature detected by the heat source temperature sensor is stable.

6. The water supply and heating system according to claim 1 or 2, wherein: The water supply heating system comprises: one or two bypass lines for bypassing the heat recovery heat exchanger with feed water and / or bypassing the heat source fluid with respect to the heat recovery heat exchanger; and The preheating mode switching unit switches between a water supply preheating mode and a preheating stop mode, wherein in the water supply preheating mode, the water supply and the heat source fluid are simultaneously circulated to the heat recovery heat exchanger, and in the preheating stop mode, at least one of the water supply and the heat source fluid is circulated to the bypass line.

7. The water supply heating system according to claim 6, wherein: The water supply heating system comprises: a water supply temperature sensor before the heat exchanger flows in, detecting the temperature of the water supply before the water flows into the heat recovery heat exchanger; and The heat source temperature sensor before the heat exchanger flows into the heat recovery heat exchanger detects the temperature of the heat source fluid before the heat exchanger flows into the heat recovery heat exchanger. The control unit compares the first detection temperature of the water supply temperature sensor before the heat exchanger flows in and the second detection temperature of the heat source temperature sensor before the heat exchanger flows in. When the first detection temperature is lower than the second detection temperature, the control unit controls the preheating mode switching unit to execute the water supply preheating mode. When the first detection temperature is higher than the second detection temperature, the control unit controls the preheating mode switching unit to execute the preheating stop mode.

8. The water supply heating system according to claim 6, wherein: The control unit has: a signal input unit receiving a preheating mode designation signal for designating a type of the water supply preheating mode or the preheating stop mode; as well as The preheating mode switching control unit controls the preheating mode switching unit according to the preheating mode designation signal input to the signal input unit so as to execute the water supply preheating mode or the preheating stop mode.

Images