CN105247293B

CN105247293B - Heat pump system

Info

Publication number: CN105247293B
Application number: CN201480029131.0A
Authority: CN
Inventors: 河野秀勇; 太田孝二; 田中宏和
Original assignee: Sharp Corp; Rinnai Corp
Current assignee: Sharp Corp; Rinnai Corp
Priority date: 2013-05-22
Filing date: 2014-03-10
Publication date: 2019-04-05
Anticipated expiration: 2034-03-10
Also published as: WO2014188759A1; JP2014228193A; KR101723419B1; KR20150143845A; CN105247293A; JP5981880B2

Abstract

The present invention provides a kind of heat pump system, the heat pump system has heat pump unit, tank entities, auxiliary thermal source unit, outside air temperature testing agency and heater, wherein, heat pump unit has heat pump, which absorbs heat from outside air to heat to heat carrier；Tank entities have the storage tank for storing heat carrier；Auxiliary thermal source unit is for heating heat carrier；Outside air temperature testing agency is used to detect outside air temperature；Heater is set to the flow path that heating load carrier flows between storage tank and heat pump.In the heat pump system, heat carrier freezes in order to prevent, it can implement to be directed at the antifreeze operating that heat carrier is heated while recycling heat carrier between storage tank and heat pump, during implementing antifreeze operating, when outside air temperature is higher, heat carrier is heated by heat pump, when outside air temperature is lower, heat carrier is heated by heater.

Description

Heat pump system

Technical Field

The present invention relates to a heat pump system.

Background

Japanese laid-open patent publication No. 2009-156495 discloses a heat pump system having a heat pump unit having a heat pump that absorbs heat from outside air to heat a heat carrier (a medium substance that transfers heat), and a reservoir unit having a reservoir for storing the heat carrier. In this heat pump system, in order to prevent the heat carrier from freezing, an anti-freeze operation may be performed, in which the heat carrier is heated while circulating between the accumulator and the heat pump. In this heat pump system, the heat pump heats the heat carrier during the antifreeze operation.

In general, since the heat carrier is heated by the heat pump and the energy saving efficiency is high, it is preferable that the heat carrier is also heated by the heat pump in order to prevent the heat carrier from freezing. In a system having only a heat pump as a heat source, it is necessary to perform not only the freeze-proof operation but also the heat storage in the accumulator, for example, to store hot water for hot water supply, in a situation where the outside air temperature is low. However, when the heat pump is started in a state where the outside air temperature is low, there is a possibility that frost is formed on an evaporator that exchanges heat between a refrigerant (cooling medium) of the heat pump and the outside air. If frost forms on the evaporator, condensed water is generated as the defrosting operation proceeds, and thus additional measures are required to prevent the condensed water from freezing. In particular, in a system in which only the heat pump has a heat source, a defrosting operation must be performed first, and therefore measures for preventing condensed water from freezing must be taken. Therefore, it is desirable to keep the evaporator of the heat pump from frosting as much as possible.

Disclosure of Invention

The present invention has been made in view of the above circumstances. The purpose of the present invention is to provide a technique that can prevent the occurrence of frost formation on the evaporator of a heat pump due to the implementation of an anti-freeze operation in a heat pump system that stores heat stored in a storage tank by storing a heat carrier heated by a heat pump.

The heat pump system according to the present invention includes a heat pump unit having a heat pump that absorbs heat from outside air to heat a heat carrier, a tank unit, and an auxiliary heat source unit; the tank unit has a tank for storing a heat carrier; the auxiliary heat source unit is used for heating the heat carrier. The heat pump system is also provided with an outside air temperature detection mechanism and a heater, wherein the outside air temperature detection mechanism is used for detecting the outside air temperature; the heater is disposed in a flow path through which the heat carrier flows between the storage tank and the heat pump. In this heat pump system, in order to prevent the heat carrier from freezing, an anti-freeze operation of heating the heat carrier while circulating the heat carrier between the accumulator and the heat pump can be performed. In the process of implementing anti-freezing operation, when the outside air temperature is higher, the heat pump heats the heat carrier, and when the outside air temperature is lower, the heater heats the heat carrier.

In the heat pump system, the heating mechanism used in the freeze-proof operation is switched according to the outside air temperature. When the outside air temperature is higher, the heat pump heats the heat carrier, so that the energy-saving efficiency can be improved. In addition, when the outside air temperature is low, the heat carrier is heated by the heater, and the heat carrier is not heated by the heat pump, so that the frost formation on the evaporator of the heat pump can be prevented. The heat pump system can prevent frost formation on the evaporator of the heat pump caused by the anti-freezing operation. In the heat pump system, even if the heat pump unit is not started up when the outside air temperature is low, the heat carrier can be heated by the heat source auxiliary unit, and hot water for supplying hot water, for example, can be generated and supplied, so that convenience is not impaired. The auxiliary heat source unit may be, for example, a gas heat source device, a gas engine cogeneration unit (gas cogeneration), a fuel cell, a heater, or the like, as long as it is a heat source that does not frost with the start-up.

In the heat pump system, the heater may be provided in the flow path inside the accumulator unit.

With the heat pump system, the detection value of the thermistor (thermistor for detecting the temperature of the heat carrier, or thermistor for detecting the temperature of the refrigerant circulating in the heat pump) in the heat pump unit can be prevented from being affected by the heat emitted from the heater.

In the heat pump system, the heater may be provided in a flow path through which the heat carrier returns from the heat pump to the storage tank.

Generally, the probability of freezing of the heat carrier in the flow path for transporting the heat carrier from the storage tank to the heat pump is higher than the probability of freezing of the heat carrier in the flow path for returning the heat carrier from the heat pump to the storage tank. Therefore, the determination as to whether or not the freeze-proof operation is to be performed is often performed based on the heat carrier temperature detected in the flow path for conveying the heat carrier from the accumulator to the heat pump. In the heat pump system, the heater is provided in the flow path through which the heat carrier is returned from the heat pump to the storage tank, and therefore, the detection value of the thermistor provided in the flow path through which the heat carrier is transferred from the storage tank to the heat pump can be prevented from being affected by the heat emitted from the heater.

The heat pump system according to the present invention can prevent the occurrence of frost formation on the evaporator of the heat pump due to the anti-freeze operation.

Drawings

Fig. 1 is a schematic structural view of a hot water supply system 10 according to an embodiment.

Fig. 2 is a flowchart for explaining the antifreeze operation performed by the hot water supply system 10 according to the embodiment.

Fig. 3 is a schematic configuration diagram of a modification of the hot water supply system 10 according to the embodiment.

Detailed Description

(examples)

Fig. 1 shows a configuration of a hot water supply system 10 according to the present embodiment. As shown in fig. 1, the water supply system 10 has a hot water storage unit 20, an HP heat source unit 40, a gas heat source unit 50, and a controller 11.

The HP heat source unit 40 has a heat pump 40a, the heat pump 40a includes a compressor 41, a 1 st heat exchanger 43 as a condenser, an expansion valve 44, and a 2 nd heat exchanger 45 as an evaporator. In the heat pump 40a, the discharge side of the compressor 41, the four-way valve 42, the refrigerant passage 43a of the 1 st heat exchanger 43, the expansion valve 44, the 2 nd heat exchanger 45, the four-way valve 42, and the suction side of the compressor 41 are connected in this order by a refrigerant pipe 46, and the refrigerant circulates in this order. The refrigerant may be R744 (CO), for example₂Refrigerant) may be R410A (HFC refrigerant). The 1 st heat exchanger 43 has a refrigerant flow path 43a and a circulating water flow path 43 b. A fan 45a is provided near the 2 nd heat exchanger 45. The 2 nd heat exchanger 45 exchanges heat between the outside air sent from the fan 45a and the refrigerant. A defrosting path 47 is connected to the refrigerant pipe 46, and the defrosting path 47 is connected between the discharge side of the compressor 41 and the four-way valve 42, and between the expansion valve 44 and the 2 nd heat exchanger 45. A defrost valve 47a is provided in the defrost path 47.

The circulating water flow path 43b of the 1 st heat exchanger 43 has an inlet side connected to the circulation outward connection path 48 and an outlet side connected to the circulation return connection path 49. An inlet-side thermistor 48a is provided in the circulation leading connection path 48, and an outlet-side thermistor 49a is provided in the circulation returning connection path 49. The inlet-side thermistor 48a detects the temperature of the circulating water flowing into the circulating water flow path 43b of the 1 st heat exchanger 43, and the outlet-side thermistor 49a detects the temperature of the circulating water flowing out of the circulating water flow path 43b of the 1 st heat exchanger 43. In practice, the thermistors 48a and 49a output detection signals in accordance with the water temperature, and the signals are input to the controller 11 to detect the water temperature. In the following description, the expression that the thermistor or the sensor detects the temperature or the flow rate means that the detection signal is actually input to the controller 11 to detect the temperature or the flow rate of the water.

The hot-water storage unit 20 has a hot-water storage tank 21 and a mixer 24. The bottom of the hot water storage tank 21 is connected to a water supply path 22, and the water supply path 22 is used to supply tap water to the hot water storage tank 21. A pressure reducing valve 23 is provided in the vicinity of the tap water inlet 22a of the water supply path 22. The pressure reducing valve 23 adjusts the feed water pressure to the feed water path 22. A portion of the feed water path 22 on the downstream side of the pressure reducing valve 23 is connected to a mixed feed water path 26 of the mixer 24. The mixed water feed path 26 is provided with a water feed control valve 26a, a water feed flow sensor 26b, and a water feed thermistor 26 c. The feed water control valve 26a is used to adjust the flow rate of the tap water flowing through the mixed feed water path 26. The feed water flow sensor 26b and the feed water thermistor 26c are used to detect the flow rate and temperature of the tap water flowing through the mixed feed water path 26. When the hot water in the hot water storage tank 21 decreases or the water supply control valve 26a opens, the pressure on the downstream side of the pressure reducing valve 23 decreases. When the pressure on the downstream side decreases, the pressure reducing valve 23 opens, and at this time, the pressure reducing valve 23 maintains the pressure at a predetermined pressure adjustment value. Therefore, when the warm water in the hot-water storage tank 21 decreases or the water supply control valve 26a of the mixer 24 is opened, the tap water is supplied accordingly.

The water feed path 22 is connected to the drain path 31 at a portion located downstream of the connection portion of the mixed water feed path 26. A drain valve 32 is provided in the middle of the drain path 31. The drain valve 32 can be opened and closed manually. When the drain valve 32 is opened, the water in the hot-water storage tank 21 is discharged to the outside through the drain path 31.

The bottom of the hot water storage tank 21 is connected to one end of the circulation outward path 33, and the upper portion of the hot water storage tank 21 is connected to one end of the circulation return path 34. The other end of the circulation outward path 33 is connected to a circulation outward path connecting path 48 of the HP heat source unit 40, and the other end of the circulation return path 34 is connected to a circulation return path connecting path 49. The outgoing circulation path 33 is provided with an outgoing thermistor 36 and a circulation pump 37. The outgoing thermistor 36 detects the temperature of the water flowing from the hot water storage tank 21 into the circulation outgoing path 33. When the circulation pump 37 is activated, water is sucked into the circulation outward passage 33 from the lower portion of the hot-water storage tank 21, and the water flows through the circulation water flow passage 43b of the 1 st heat exchanger 43 and returns to the upper portion of the hot-water storage tank 21 through the circulation return passage 34. In this way, a circulation path is formed between the hot-water storage tank 21 and the heat pump 40 a.

An antifreeze heater 34a for using electricity is provided in the circulation return path 34 inside the hot water storage unit 20. The circulation return passage 34 is connected to a pressure release passage 38 at a middle portion thereof, and a relief valve 38a is provided in the pressure release passage 38. The valve opening pressure of the relief valve 38a is set to be slightly larger than the pressure adjustment value of the pressure reducing valve 23. When the pressure cannot be adjusted by the pressure reducing valve 23, the relief valve 38a is opened to prevent the pressure in the hot water storage tank 21 from exceeding the pressure that the hot water storage tank 21 can receive. An upper thermistor 39 is attached to the hot water storage tank 21 at a predetermined amount (for example, 30 liters) from the upper end thereof. The upper thermistor 39 detects the temperature of water in the upper portion of the hot water storage tank 21. The hot water storage unit 20 is provided with an outside air temperature thermistor 35 for detecting an outside air temperature.

The hot water path 25 of the mixer 24 is connected to the upper part of the hot water storage tank 21. The warm water path 25 is provided with a warm water control valve 25a, a warm water flow sensor 25b, and a warm water thermistor 25 c. The warm water control valve 25a is used to adjust the flow rate of water flowing from the hot water storage tank 21 into the warm water path 25. The hot water flow sensor 25b detects the flow rate of water flowing from the hot water storage tank 21 into the hot water path 25. The warm water thermistor 25c is used to detect the temperature of the water flowing through the warm water path 25. The junction of the warm water path 25 and the mixed water supply path 26 and the 1 st mixing path

Stopping working, and finishing the anti-freezing operation.

The hot water storage unit 20 has a 1 st hot water supply path 29. The 1 st hot water supply path 29 is provided with a hot water supply thermistor 29 a. The front end of the 1 st feed water path 29 is connected to a hot water tap 60. The hot water taps 60 are disposed in a bathroom, a washing room, a kitchen, etc. (in fig. 1, only one hot water tap 60 represents these hot water taps 60). The 1 st mixing path 27 and the 1 st hot water supply path 29 are connected by a hot water supply bypass 28. A bypass control valve 28a is provided in the hot water supply bypass 28. The mixed water having passed through the 1 st mixing path 27 flows into the hot water supply bypass 28 in a state where the bypass control valve 28a is open, and the mixed water having passed through the 1 st mixing path 27 flows into the 2 nd mixing path 51 of the gas heat source unit 50 described later in a state where the bypass control valve 28a is closed.

The gas heat source unit 50 has a heat exchanger 52, a burner 53, and the like. The mixed water from the 1 st mixing path 27 of the hot water storage unit 20 flows into the heat exchanger 52 through the 2 nd mixing path 51. The 2 nd mixing path 51 is provided with an inlet thermistor 51a, a hot water supply flow sensor 51b, and a water amount control mechanism 51 c. The inlet thermistor 51a and the hot water supply flow rate sensor 51b are used to detect the temperature and flow rate of water flowing through the 2 nd mixing path 51, respectively. The water amount control mechanism 51c is used to adjust the flow rate of water flowing through the 2 nd mixing path 51. The heat exchanger 52 is heated by a gas burner 53. The water heated in the heat exchanger 52 flows into the 1 st hot water supply path 29 of the hot water storage unit 20 through the 2 nd hot water supply path 54. In the 2 nd hot water supply path 54, a tank thermistor 55 is provided near the outlet of the heat exchanger 52, and a hot water discharge thermistor 56 is provided downstream of the tank thermistor 55. The downstream side of the water amount control mechanism 51c in the 2 nd mixing path 51 is connected to one end of a heat source device bypass 57, and the other end of the heat source device bypass 57 is connected between the tank thermistor 55 and the hot water discharge thermistor 56 in the 2 nd hot water supply path 54. A heat source device bypass control valve 58 is provided at a connection portion between the 2 nd mixing path 51 and the heat source device bypass 57. By adjusting the opening degree of the heat-source-device bypass control valve 58, a part of the water flowing through the 2 nd mixing path 51 can be made to flow into the heat-source-device bypass 57, and the flow rate of the water flowing into the heat-source-device bypass 57 can be adjusted.

The controller 11 has a CPU, ROM, RAM, and the like. The ROM stores programs for executing various operations. The RAM temporarily stores various signals input to the controller 11 and various data generated during execution of processing by the CPU. Specifically, the detection signals of the various thermistors 25c, 26c, 27a, 29a, 35, 36, 39, 48a, 49a, 51a, 55, 56 and the flow sensors 25b, 26b, 51b are input to the RAM, and the RAM temporarily stores these pieces of information. The CPU of the controller 11 outputs activation signals to various devices of the hot water storage unit 20, the HP heat source unit 40, and the gas heat source unit 50 based on information stored in the ROM or the RAM. In addition, the controller 11 is connected to a remote controller 13. The remote controller 13 is provided with a switch 16 for operating the water supply system 10, a liquid crystal display 17 for displaying an operation state of the water supply system 10, and the like, and information set by the remote controller 13 is input to the controller 11.

(regenerative operation)

The hot water supply system 10 can perform a heat storage operation in which water in the hot water storage tank 21 is heated by the heat pump 40a to obtain high-temperature hot water, and the hot water is stored in the hot water storage tank 21.

In the heat storage operation state, the compressor 41 in the HP heat source unit 40 is started. The refrigerant compressed by the compressor 41 flows through the refrigerant passage 43a of the 1 st heat exchanger 43, and the refrigerant heats the circulating water flowing through the circulating water passage 43b when flowing through the refrigerant passage 43. The refrigerant flowing out of the refrigerant passage 43a is expanded and cooled by the expansion valve 44, and the cooled refrigerant absorbs heat from the outside air and increases in temperature when passing through the 2 nd heat exchanger 45. The refrigerant having been heated flows into the compressor 41 and is compressed again, thereby further heating the refrigerant.

In the hot-water storage unit 20, the circulation pump 37 is operated, and the water in the hot-water storage tank 21 is sucked out from the bottom of the hot-water storage tank 21 to the circulation path 33. The water sucked out to the circulation outward passage 33 is heated and rises in temperature when passing through the circulation water flow passage 43b of the 1 st heat exchanger 43 of the HP heat source unit 40. The warm water having the increased temperature returns to the upper portion of the hot water storage tank 21 through the circulation return passage 34. By performing this circulation, a high-temperature layer is stacked on the low-temperature layer in the hot water storage tank 21, thereby forming a temperature layer. The hot water of high temperature continuously returns to the hot water storage tank 21, and the thickness (depth) of the high temperature layer gradually increases, and when the maximum heat storage state is reached, the hot water of high temperature is stored in the whole hot water storage tank 21. When the temperature layer is formed in the hot-water storage tank 21, high-temperature hot water can be supplied to the hot-water path 25 connected to the upper portion of the hot-water storage tank 21 even if the maximum amount of stored heat is not reached.

(supply hot water running)

In the hot water supply operation state, a 1 st hot water supply operation or a 2 nd hot water supply operation is performed, wherein the 1 st hot water supply operation is that the temperature of the mixed water is adjusted to the hot water supply set temperature by the mixer 24, the mixed water adjusted to the hot water supply set temperature reaches the hot water faucet 60 through the hot water supply bypass 28, and the hot water is supplied by the hot water faucet 60; in the 2 nd hot water supply operation, the temperature of the mixed water is adjusted to a temperature lower than the set temperature of the hot water supply by the mixer 24, the temperature-adjusted mixed water is heated by the gas heat source unit 50, and then the hot water is supplied from the hot water faucet 60.

When the temperature of the water detected by the upper thermistor 39 of the hot water storage tank 21 is not lower than the 1 st reference temperature (for example, the hot water supply set temperature +5 ℃) higher than the hot water supply set temperature set by the remote controller 13, the 1 st hot water supply operation is executed. In the 1 st water supply operation, the controller 11 opens the bypass control valve 28a and fully closes the water level control mechanism 51 c. The controller 11 adjusts the opening degree of the warm water control valve 25a and the opening degree of the feedwater control valve 26a so that the temperature of the water detected by the mixing thermistor 27a reaches the feedwater set temperature. The mixed water adjusted to the set temperature of the hot water is supplied from the hot water tap 60 by passing through the 1 st mixing path 27, the hot water bypass 28, and the 1 st hot water supply path 29.

When the water temperature detected by the upper thermistor 39 does not reach the 1 st reference temperature, the 2 nd water supply operation is executed. In the 2 nd water supply operation state, the controller 11 sets the bypass control valve 28a in the fully closed state and sets the opening degree of the water level control mechanism 51c to a predetermined opening degree. The controller 11 adjusts the opening degree of the warm water control valve 25a and the opening degree of the hot water supply control valve 26a so that the temperature of the water detected by the mixing thermistor 27a reaches the 2 nd reference temperature (for example, the hot water supply set temperature-5 c) lower than the hot water supply set temperature. The mixed water adjusted to the 2 nd reference temperature flows through the 1 st mixing path 27, then flows through the 2 nd mixing path 51 of the gas heat source unit 50, flows into the heat exchanger 52, and is heated by the burner 53. The heating capacity of the burner 53 is controlled so that the water temperature detected by the tank thermistor 55 provided at the outlet of the heat exchanger 52 is 60 ℃ or higher. This can suppress the generation of condensed water in the pipe. Part of the mixed water flowing through the 2 nd mixing path 51 flows into the 2 nd hot water supply path 54 through the heat source device bypass 57, and the water having a temperature of 60 ℃ or higher from the heat exchanger 52 is mixed with the water having a temperature of the 2 nd reference temperature from the heat source device bypass 57 to become water having a temperature set for the hot water supply, and is sent to the 1 st hot water supply path 29. In this way, the water whose temperature is adjusted to the hot water supply set temperature reaches the hot water faucet 60 through the 1 st hot water supply path 29, and the hot water is supplied from the hot water faucet 60. Thus, even when the hot water stored in the hot water storage tank 21 is used up in the 1 st hot water supply operation, the hot water adjusted to the hot water supply set temperature can be continuously supplied.

(defrosting operation)

When the heat pump 40a is started in a state where the outside air temperature is low, such as in winter, frost may form on the 2 nd heat exchanger 45. If frost forms on the 2 nd heat exchanger 45, the heat exchange efficiency with the outside air is reduced, and the heating capacity of the heat pump 40a for the circulating water is reduced. Therefore, in the hot water supply system 10 according to the present embodiment, when frost is formed on the 2 nd heat exchanger 45, a defrosting operation for removing the frost from the 2 nd heat exchanger 45 can be performed. In the defrosting operation, the HP heat source unit 40 starts the compressor 41 with the defrosting valve 47a opened. Accordingly, as indicated by a dotted arrow in fig. 1, the high-temperature refrigerant discharged from the compressor 41 flows into the 2 nd heat exchanger 45 through the defrosting path 47, and then returns to the compressor 41, thereby circulating. By passing the high-temperature refrigerant through the 2 nd heat exchanger 45, frost can be removed from the 2 nd heat exchanger 45.

(anti-freeze run)

When the heat storage operation is not performed for a long time in a state where the outside air temperature is low such as in winter, the circulating water remaining in the circulating water flow path 43b, the outward circulation path 33, the outward circulation path connection path 48, the return circulation path connection path 49, and the return circulation path 34 of the 1 st heat exchanger 43 may freeze in the pipes. If the circulating water is frozen, the heat storage operation cannot be performed until the frozen circulating water is melted. Therefore, in the hot water supply system 10 according to the present embodiment, when the outside temperature is low and the temperature of the circulating water is lowered, the anti-freeze operation for preventing the freezing of the circulating water can be performed. Next, the antifreeze operation performed by the hot water supply system 10 will be described with reference to fig. 2.

In step S202, it is determined whether or not the circulating water temperature is lower than a predetermined temperature (for example, 10 ℃). In the following description, the circulating water temperature is the lower one of the circulating water temperature in the outgoing circulation path 33 detected by the outgoing thermistor 36 and the circulating water temperature in the outgoing circulation path connection path 48 detected by the incoming thermistor 48 a. When the judgment result shows that the circulating water temperature is equal to or higher than the predetermined temperature (NO in step S202), the operation returns to the starting state and starts again from step S202. If the determination result is that the circulating water temperature is lower than the predetermined temperature (step S202: YES), the flow proceeds to step S204.

In step S204, it is determined whether or not the outside air temperature detected by the outside air temperature thermistor 35 is lower than a predetermined temperature (for example, 5 ℃). When the outside air temperature is equal to or higher than the predetermined temperature as a result of the determination (NO at step S204), the process returns to step S202. If the outside air temperature is lower than the predetermined temperature as a result of the determination (yes in step S204), the process proceeds to step S206.

In step S206, the circulation pump 37 is started. Thus, the circulating water is sucked out from the lower portion of the hot water storage tank 21, flows through the outward circulation path 33, the outward circulation path connection path 48, the circulating water flow path 43b of the 1 st heat exchanger 43, the return circulation path connection path 49, and the return circulation path 34 in this order, and then returns to the upper portion of the hot water storage tank 21. By thus flowing the circulating water, the circulating water inside the outward circulation path 33, the outward circulation path connecting path 48, the circulating water flow path 43b of the 1 st heat exchanger 43, the return circulation path connecting path 49, and the return circulation path 34 is replaced.

In step S208, it is determined whether or not the circulating water temperature (lower one of the circulating water temperature in the outward circulation path 33 detected by the outward thermistor 36 and the circulating water temperature in the outward circulation path connection path 48 detected by the inlet thermistor 48 a) is equal to or higher than a predetermined temperature (for example, 13 ℃). When the freeze preventing operation is started in step S206 and residual heat remains in the hot-water storage tank 21, the circulation pump 37 is activated so that the circulating water in the outward circulation path 33, the outward circulation path connection path 48, the circulating water flow path 43b of the 1 st heat exchanger 43, the return circulation path connection path 49, and the return circulation path 34 is replaced with relatively warm circulating water from the hot-water storage tank 21. At this time, it is not necessary to continue the freeze preventing operation. Therefore, when the determination result in step S208 is that the circulating water temperature is equal to or higher than the predetermined temperature (when the determination result is yes), the routine proceeds to step S228, and the operation of the circulating pump 37 is stopped to end the anti-freeze operation. If the determination result in step S208 is that the circulating water temperature is lower than the predetermined temperature (if the determination result is "no"), the process proceeds to step S210.

In step S210, it is determined whether or not the outside air temperature is equal to or higher than a predetermined temperature (for example, 6 ℃). After the start of the freeze-proofing operation in step S206, when the outside air temperature rises to a temperature at which the circulating water is not frozen, there is no need to continue the freeze-proofing operation. Therefore, when the outside air temperature is equal to or higher than the predetermined temperature as a result of the determination in step S210 (when the determination result is yes), the process proceeds to step S228, and the operation of circulation pump 37 is stopped to end the freeze-proofing operation. If the outside air temperature is lower than the predetermined temperature as a result of the determination in step S210 (if the determination result is no), the process proceeds to step S212.

In step S212, it is determined whether or not a predetermined time (for example, 30 minutes) has elapsed after circulation pump 37 is started in step S206. When the judgment result is that the predetermined time has not elapsed (step S212: NO), the process returns to step S208. When the predetermined time has elapsed as a result of the judgment (YES at step S212), the flow proceeds to step S214. The condition for the process from step S212 to step S214 is that the circulating water temperature is lower than the predetermined temperature (that is, no residual heat remains in the hot-water storage tank 21) and the outside air temperature does not rise until the predetermined time elapses after the circulation pump 37 is started. In this case, the hot water supply system 10 according to the present embodiment performs the processing after step S214 to heat the circulating water.

In step S214, it is determined whether or not the outside air temperature is lower than a predetermined temperature (for example, -10 ℃). In general, the energy saving efficiency of heating the circulating water by the heat pump 40a is high, and therefore, it is preferable that the heat pump 40a also heats the circulating water to prevent freezing. However, when the heat pump 40a performs heating in a situation where the outside air temperature is low, frost may form on the 2 nd heat exchanger 45. If frost forms on the 2 nd heat exchanger 45, condensed water is generated as the defrosting operation proceeds, and thus additional measures are required to prevent the condensed water from freezing. Therefore, it is preferable to prevent the 2 nd heat exchanger 45 from frosting as much as possible. Therefore, in the water supply system 10 according to the present embodiment, when the circulating water is heated in the freeze-protected operation, the heating mechanism is switched according to the outside air temperature.

If the outside air temperature is equal to or higher than the predetermined temperature as a result of the determination in step S214 (if the determination result is no), the process proceeds to step S216. In step S216, the compressor 41 is started to start heating the circulating water by the heat pump 40 a. In step S218, the circulation water temperature (lower one of the circulation water temperature in the circulation outward path 33 detected by the outward thermistor 36 and the circulation water temperature in the circulation outward path connection path 48 detected by the inlet thermistor 48 a) is kept in a standby state until it rises to a predetermined temperature (for example, 30 ℃). When the temperature of the circulating water rises to the predetermined temperature or higher in step S218 (yes in the determination result), the flow proceeds to step S220, where the operation of the compressor 41 is stopped, and the heating of the circulating water by the heat pump 40a is completed. Thereafter, the process proceeds to step S228, where circulation pump 37 is stopped to terminate the freeze-proofing operation.

If the outside air temperature is lower than the predetermined temperature as a result of the determination in step S214 (if the determination result is yes), the process proceeds to step S222. In step S222, the antifreeze heater 34a is turned on, and heating of the circulating water by the antifreeze heater 34a is started. In step S224, the system is in a standby state until the outside air temperature rises to a predetermined temperature (for example, -8 ℃). When the outside air temperature rises to the predetermined temperature or higher in step S224 (yes in the determination result), the routine proceeds to step S226, where the antifreeze heater 34a is turned off, and heating of the circulating water by the antifreeze heater 34a is terminated. Thereafter, the process proceeds to step S228, where circulation pump 37 is stopped to terminate the freeze-proofing operation.

As described above, in the water supply system 10 according to the present embodiment, during the freeze prevention operation, when the outside air temperature is high, the heat pump 40a heats the circulating water, and when the outside air temperature is low, the freeze prevention heater 34a heats the circulating water. With this configuration, it is possible to prevent the occurrence of the frost formation on the 2 nd heat exchanger 45 of the heat pump 40a due to the freeze preventing operation.

In the above-described water supply system 10, the antifreeze heater 34a is provided not inside the HP heat source unit 40 but inside the hot water storage unit 20. With this configuration, it is possible to prevent the detection values of the thermistors (the inlet-side thermistor 48a and the outlet-side thermistor 49a that detect the temperature of the circulating water, and the thermistor that detects the temperature of the refrigerant (not shown)) in the HP heat source unit 40 from being affected by the heat radiated from the antifreeze heater 34 a.

In addition, in the above-described hot water supply system 10, the following configuration may be adopted: when the outside air temperature is lower than a predetermined temperature (for example, -10 ℃) in the state of not only the freeze-proof operation but also the heat storage operation, the circulating water is not heated by the heat pump 40a, so that the frost formation on the 2 nd heat exchanger 45 is prevented. With this configuration, in the water supply system 10, by performing the 2 nd water supply operation using the gas heat source unit 50, water at the temperature set for water supply can be supplied to the hot water faucet 60. Therefore, the frost formation on the 2 nd heat exchanger 45 of the heat pump 40a can be prevented without impairing the convenience of the user.

In the above-described water supply system, the antifreeze heater 34a is provided not in the circulation outward path 33 but in the circulation return path 34. With this configuration, the detection value of the outgoing thermistor 36 can be prevented from being affected by the heat emitted from the antifreeze heater 34 a.

Further, as shown in fig. 3, even if the antifreeze heater 34a is provided in the circulation leading path 48 inside the HP heat source unit 40, by performing the antifreeze operation shown in fig. 2, it is possible to prevent the frost from forming on the 2 nd heat exchanger 45 of the heat pump 40a due to the antifreeze operation.

In the above-described embodiment, a description has been given of a configuration in which tap water (upper water) supplied for hot water supply is used as a heat carrier circulating between the heat pump 40a and the hot-water storage tank 21. A configuration different from this may be adopted, for example, in which the antifreeze is used as a heat carrier for circulating between the heat pump 40a and the hot water storage tank 21, and a heat exchanger for exchanging heat between the tap water (upper water) supplied when the hot water is supplied and the antifreeze stored in the hot water storage tank 21 is separately provided, so that the hot water is supplied by the stored heat in the hot water storage tank 21.

In the above-described embodiment, the structure in which the water supply system uses the heat carrier stored in the hot-water storage tank 21 is explained. A configuration different from this may be adopted, and the heat carrier stored in the hot-water storage tank 21 may be used in a heating system such as a geothermal heating system or a bathroom drying heating system, for example. Alternatively, the heat carrier stored in the hot water storage tank 21 may be used for both the hot water supply system and the heating system.

Specific examples of the present invention have been described above, but these are merely examples and do not limit the scope of the present invention. The means recited in the claims include various modifications and alterations to the specific examples illustrated above. The technical elements described in the specification and the drawings may be used alone or in combination to exhibit technical usefulness, and are not limited to the combination described in the claims at the time of filing. The techniques exemplified in the present specification and the drawings can achieve a plurality of objects at the same time, and can also exhibit technical usefulness for achieving one of the objects.

Claims

1. A heat pump system has a heat pump unit, a reservoir unit and an auxiliary heat source unit,

wherein,

the heat pump unit has a heat pump that absorbs heat from outside air to heat the heat carrier;

the tank unit has a tank for storing a heat carrier;

the auxiliary heat source unit is used for heating the heat carrier supplied from the storage tank to the heat carrier utilization part,

it is characterized in that the preparation method is characterized in that,

further comprising:

an outside air temperature detection means for detecting an outside air temperature;

a heater provided in a flow path through which a heat carrier flows between the storage tank and the heat pump,

in order to prevent the heat carrier from freezing, the anti-freezing operation of heating the heat carrier while circulating the heat carrier between the storage tank and the heat pump can be performed,

in the process of performing the freeze-proofing operation, the heat carrier is heated by the heat pump when the outside air temperature is equal to or higher than a predetermined temperature, and the heat carrier is heated by the heater without being heated by the heat pump when the outside air temperature is lower than the predetermined temperature.

2. The heat pump system of claim 1,

the heater is provided in the flow path inside the reservoir unit.

3. The heat pump system of claim 2,

the heater is provided in a flow path for returning the heat carrier from the heat pump to the storage tank.