JP2012007858A - Heat pump water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump water heater that can suppress an increase of cost and efficiently perform defrosting operation without complicating a refrigeration cycle circuit or degrading the reliability of a system.SOLUTION: The heat pump water heater 50 includes: a refrigeration cycle circuit 100 wherein a compressor 3, a water refrigerant heat exchanger 4, an expansion valve 5, and an evaporator 6 are connected in a refrigerant flow passage in this order; a hot-water supply circuit 200 wherein a hot-water storage tank 9, a water feed pump 8, a three-way valve 40, a return flow passage 10b, an upper flow passage 10c, and a lower flow passage 10e are provided; and a controller (11 and 13). The three-way valve 40 can be changed to a condition for making the return flow passage 10b communicate with the upper flow passage 10c or the lower flow passage 10e, as well as a condition for intercepting the return flow passage 10b, and the controller (11 and 13) changes the three-way valve 40 to the condition for intercepting the return flow passage 10b and actuates the water feed pump 8 at very low speed during defrosting operation of the evaporator 6.

Description

  The present invention relates to a heat pump type water heater.

  At the evaporator of the refrigeration cycle circuit, the atmospheric heat is absorbed by the refrigerant, and further the refrigerant compressed by the compressor is heated to a water refrigerant heat exchanger. The water refrigerant heat exchanger heats the water in the hot water supply water circuit. Heat pump type water heaters are widely used. When frost adheres to the evaporator of the refrigeration cycle circuit, heat exchange in the evaporator is hindered, and the efficiency of the heat pump decreases. For this reason, when the frost has adhered to the evaporator, the defrosting operation for removing this frost is performed.

  In Patent Document 1 below, as a method of performing the defrosting operation, the expansion valve of the refrigeration cycle circuit is set to a large opening and the water pump of the hot water supply circuit is stopped (hereinafter referred to as “first prior art”). In addition, a hot gas bypass passage that bypasses the water-refrigerant heat exchanger and an electromagnetic valve that opens and closes the hot gas bypass passage are provided. A method of supplying the discharged refrigerant (hot gas) to the inlet of the evaporator through the hot gas bypass (hereinafter referred to as “second prior art”) is also disclosed.

JP 2001-108256 A

  However, the first prior art has the following problems. Even if the water supply pump of the hot water supply circuit is stopped, the difference in specific gravity due to the temperature difference of the water and the influence of the installation environment (for example, there is a difference in height between the installation location of the heat pump unit and the installation location of the hot water storage tank unit) In some cases, the water in the water-refrigerant heat exchanger may move. When the water in the water-refrigerant heat exchanger moves, the heat of the refrigerant (hot gas) is taken away by the water in the water-refrigerant heat exchanger, so that the heat energy necessary for defrosting is not supplied to the evaporator, There is a possibility that the operation time may be extended or the defrosting may not be completed within the defrosting operation end time.

  Further, in the case of the second prior art, since it is necessary to add a hot gas bypass path and an electromagnetic valve to the refrigeration cycle circuit, the structure becomes complicated and the structure becomes expensive. In addition, the refrigeration cycle circuit is complicated, so that there is a problem that reliability is lowered. Furthermore, during the defrosting operation, the solenoid valve of the hot gas bypass passage is opened and the flow of the refrigerant changes, so that there is a problem that the sound of the refrigerant and the sound of the electromagnetic valve are generated.

  The present invention has been made in order to solve the above-described problems. The defrosting operation is performed without complicating the refrigeration cycle circuit, reducing the reliability of the system, and suppressing an increase in cost. It aims at providing the heat pump type hot water heater which can be performed efficiently.

  The heat pump type hot water heater according to the present invention includes a compressor that compresses a refrigerant, a water refrigerant heat exchanger for heating water by the refrigerant compressed by the compressor, an expansion valve, and an evaporator in this order. A refrigeration cycle circuit connected by a flow path, a hot water storage tank, a water supply pump provided in the middle of the flow path for sending water taken from the lower part of the hot water storage tank to the water refrigerant heat exchanger, a three-way valve, and a water refrigerant A return flow path connecting the water outlet of the heat exchanger and the three-way valve, an upper flow path connecting the three-way valve and the upper part of the hot water tank, and a lower flow path connecting the three-way valve and the lower part of the hot water tank. And a control means for controlling the refrigeration cycle circuit and the hot water supply circuit, and the three-way valve communicates the return flow path with the upper flow path and the return flow path with the lower flow path. Can be switched between a state and a state where the return flow path is blocked There, the control means is for driving the defrosting operation to perform defrosting of the evaporator, the water pump switches the three-way valve in a state of blocking the return channel at a very slow speed.

  According to the present invention, since the defrosting operation can be performed without changing the refrigerant circulation path of the refrigeration cycle circuit, the refrigeration cycle circuit can be prevented from being complicated, the cost can be reduced, and the reliability of the system can be reduced. Can be prevented. In addition, during the defrosting operation, it is possible to prevent the refrigerant (hot gas) discharged from the compressor from radiating heat with the water refrigerant heat exchanger as much as possible, and to the evaporator while maintaining the refrigerant reliably at a high temperature. Since it can be sent, defrosting can be performed quickly and efficiently.

It is a figure which shows the whole structure of the heat pump type hot water heater which concerns on Embodiment 1 of this invention. It is sectional drawing of the three-way valve with which the heat pump type water heater shown in FIG. 1 is provided (a state in which the return flow path communicates with the upper flow path). FIG. 2 is a cross-sectional view of a three-way valve provided in the heat pump hot water supply device shown in FIG. 1 (a state in which a return flow path is communicated with a lower flow path). It is sectional drawing (state which interrupts | blocks a return flow path) of the three-way valve with which the heat pump type water heater shown in FIG. It is sectional drawing (state which interrupts | blocks a return flow path) of the three-way valve with which the heat pump type water heater shown in FIG. It is sectional drawing (state which interrupts | blocks a return flow path) of the three-way valve with which the heat pump type water heater shown in FIG. It is sectional drawing (state which interrupts | blocks a return flow path) of the three-way valve with which the heat pump type water heater shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an overall configuration of a heat pump type hot water heater 50 according to Embodiment 1 of the present invention. As shown in FIG. 1, the heat pump type hot water heater 50 of this embodiment includes a heat pump unit 1 and a hot water storage tank unit 2. In the heat pump unit 1, a compressor 3, a water / refrigerant heat exchanger 4, an expansion valve 5 and an evaporator 6 are sequentially connected in an annular manner, and the outside air is sent to the refrigeration cycle circuit 100 in which the refrigerant circulates and the evaporator 6. A fan 7 is mounted.

  In the hot water storage tank unit 2, a water supply pump 8 that sends water, which is a load-side medium, to the water refrigerant heat exchanger 4, and a hot water storage tank 9 that stores high temperature water generated by being heated by the water refrigerant heat exchanger 4. And a three-way valve 40 is mounted. The lower part of the hot water storage tank 9 and the suction port of the water supply pump 8 are connected by a forward flow path 10d. The discharge port of the water pump 8 and the water inlet of the water-refrigerant heat exchanger 4 are connected by the forward flow path 10a. The water outlet of the water-refrigerant heat exchanger 4 and the three-way valve 40 are connected by a return channel 10b. One end of the upper channel 10c and one end of the lower channel 10e are further connected to the three-way valve 40. The other end of the upper flow path 10 c is connected to the upper part of the hot water storage tank 9. The other end of the lower flow path 10 e is connected to the lower part of the hot water storage tank 9. In the present embodiment, the hot water supply circuit 200 is configured by the above-described elements. The water pump 8 is not necessarily installed in the hot water storage tank unit 2 and may be installed on the heat pump unit 1 side.

  A water supply pipe 30 for supplying water into the hot water storage tank 9 is further connected to the lower part of the hot water storage tank 9. In the middle of the water supply pipe 30, a pressure reducing valve 31 for reducing the water supply pressure to a predetermined pressure or less is installed. A mixed hot water supply pipe 32 is further connected to the upper part of the hot water storage tank 9. The mixed hot water supply pipe 32, the mixed water supply pipe 33 branched from the water supply pipe 30, and the hot water supply pipe 35 for supplying hot water to a hot water supply destination (for example, a bathtub, a shower, a kitchen faucet, etc.) It is connected to the. The hot water supply mixing valve 34 supplies hot water whose temperature is adjusted by mixing high temperature water from the mixed hot water supply pipe 32 and low temperature water from the mixed hot water supply pipe 33 to the hot water supply pipe 35.

  The heat pump type hot water heater 50 of the present embodiment includes a control device 11 and a system control device 13 as control means. The control device 11 provided in the heat pump unit 1 is based on measurement information by a temperature sensor (not shown) or the like, contents of operation command information instructed by a user via a remote control device (not shown), and the like. The compressor 3 has a function of controlling the operation method (pressure, temperature, etc. of discharged refrigerant), the opening degree of the expansion valve 5, the operation method of the fan 7, and the operation method of the water pump 8. The system control device 13 provided in the hot water storage tank unit 2 has a function of controlling the entire heat pump unit 1 and the hot water storage tank unit 2 as a system.

  FIG. 1 shows only the basic configuration of the heat pump type hot water heater 50, and it is possible to arbitrarily add a configuration for other purposes. In addition, as the refrigerant of the heat pump type hot water heater 50, a refrigerant capable of producing high temperature hot water, for example, a refrigerant such as carbon dioxide, R410A, and propane is suitable, but is not particularly limited thereto.

  2 to 7 are cross-sectional views of the three-way valve 40 provided in the heat pump type water heater 50 shown in FIG. As shown in these drawings, a valve body 15 having a substantially “L” -shaped hole through which water can flow is rotatably installed inside the three-way valve 40. The three-way valve 40 can be switched to the state shown in FIGS. 2 to 7 as the valve body 15 rotates. FIG. 2 shows a state in which the return channel 10b communicates with the upper channel 10c. At the time of the heating operation described later, the three-way valve 40 is in the state shown in FIG. In this state, the water in the lower flow path 10e exists without being mixed with the water in the return flow path 10b and the upper flow path 10c.

  FIG. 3 shows a state in which the return channel 10b communicates with the lower channel 10e. In this state, the water in the upper flow path 10c exists without being mixed with the water in the return flow path 10b and the lower flow path 10e. In the heat pump type water heater 50, when the temperature of the water coming out of the water refrigerant heat exchanger 4 is not stable, the water discharged from the water refrigerant heat exchanger 4 is switched by switching the three-way valve 40 to the state shown in FIG. Can be returned to the lower part of the hot water storage tank 9. Thereby, it is possible to prevent non-high temperature water from flowing into the upper part of the hot water storage tank 9.

  FIG. 4 shows a state where the return flow path 10b is blocked. In the three-way valve 40 of the present embodiment, in this state, the upper flow path 10c and the lower flow path 10e are simultaneously blocked. For this reason, in this state, the water in the return flow path 10b, the upper flow path 10c, and the lower flow path 10e can exist without being mixed with each other. Further, not only when the valve body 15 is stopped at the position shown in FIG. 4, but also when the valve body 15 is stopped at any of the positions shown in FIGS. The flow path 10c and the lower flow path 10e are blocked. In the following description, the state of the three-way valve 40 shown in FIGS. 4 to 7 is referred to as a “cut-off state”.

(Boiling operation)
Next, the operation | movement operation | movement with this heat pump type hot-water supply machine 50 is demonstrated. First, the boiling operation will be described. In the boiling operation, the refrigeration cycle circuit 100 and the hot water supply circuit 200 are operated, the low-temperature water is discharged from the lower part of the hot water storage tank 9 by the water supply pump 8, and is supplied to the water refrigerant heat exchanger 4 for water refrigerant heat exchange. In this operation, heat is exchanged with the refrigerant in the vessel 4 to produce high-temperature water, and this high-temperature water is returned to the upper part of the hot water storage tank 9.

  In the refrigeration cycle circuit 100 of the heat pump unit 1, the high-temperature and high-pressure gas refrigerant discharged from the compressor 3 decreases in temperature while radiating heat (heats water) to the hot water supply circuit 200 side by the water-refrigerant heat exchanger 4. At this time, if the high-pressure side refrigerant pressure is equal to or higher than the critical pressure, the refrigerant radiates heat by lowering the temperature without undergoing a gas-liquid phase transition in a supercritical state. If the high-pressure side refrigerant pressure is equal to or lower than the critical pressure, the refrigerant radiates heat while liquefying. That is, hot water supply heating (boiling) is performed by applying heat radiated from the refrigerant to the load-side medium (here, water flowing through the hot water supply water circuit 200). The high-pressure and low-temperature refrigerant flowing out of the water-refrigerant heat exchanger 4 through hot water heating passes through the expansion valve 5.

  The refrigerant that has passed through the expansion valve 5 is decompressed to a low-pressure gas-liquid two-phase state. The refrigerant that has passed through the expansion valve 5 flows into the evaporator 6, where it absorbs heat from the outside air and is evaporated into gas. The low-pressure refrigerant exiting the evaporator 6 is sucked into the compressor 3 and circulated to form a refrigeration cycle.

  On the hot water supply circuit 200 side, the water in the hot water storage tank 9 is guided from the lower part of the hot water storage tank 9 by the water supply pump 8, passes through the forward flow paths 10 d and 10 a, and is conveyed into the water refrigerant heat exchanger 4. The Then, it is heated (boiling) by exchanging heat with the refrigerant, and flows into the hot water storage tank 9 from the upper part of the hot water storage tank 9 through the return flow path 10b, the three-way valve 40, and the upper flow path 10c. By performing such a boiling operation, high-temperature water is stored in the hot water storage tank 9 sequentially from the upper part to the lower part of the hot water storage tank 9.

(Defrosting operation)
Next, the defrosting operation in the heat pump type hot water heater 50 will be described. The defrosting operation is an operation for melting the frost attached to the evaporator 6 with the heat of the high-temperature refrigerant (hot gas) discharged from the compressor 3. When performing the boiling operation, if frost adheres to the evaporator 6, heat exchange in the evaporator 6 is hindered, and the heating capacity is reduced. For this reason, when frost has adhered to the evaporator 6, the boiling operation is temporarily interrupted to perform the defrosting operation, and the frost in the evaporator 6 is removed.

  The refrigerant circulation path during the defrosting operation in the heat pump hot water heater 50 is the same as that during the boiling operation. That is, the refrigerant discharged from the compressor 3 reaches the evaporator 6 via the water refrigerant heat exchanger 4 and the expansion valve 5. In order to efficiently perform this defrosting operation, the heat energy of the refrigerant (hot gas) discharged from the compressor 3 is kept as high as possible without giving the heat energy in the hot water supply circuit 200 as much as possible. It is important to send to the evaporator 6. When water in the hot water supply circuit 200 circulates and water flows in the water-refrigerant heat exchanger 4, heat exchange occurs in the water-refrigerant heat exchanger 4, and the heat energy of the refrigerant (hot gas) is reduced to water. Will be taken away by. Therefore, conventionally, the water pump 8 is stopped during the defrosting operation, and the circulation of water in the hot water supply circuit 200 is stopped.

  However, even when the water pump 8 is in a stopped state, the difference in specific gravity due to the temperature difference of water or the influence of the installation environment (for example, the difference in height between the installation location of the heat pump unit 1 and the installation location of the hot water storage tank unit 2) In some cases, the water in the hot water supply circuit 200 may move. When the water in the hot water supply circuit 200 moves, heat is transferred from the refrigerant (hot gas) to the water inside the water-refrigerant heat exchanger 4, and the heat energy of the refrigerant (hot gas) is taken away by the water. End up. As a result, the heat energy supplied to the evaporator 6 decreases, and the problem that the defrosting operation time is extended or the defrosting is not completed within the defrosting operation end time occurs.

  Therefore, in the present embodiment, during the defrosting operation, the three-way valve 40 is switched to the shut-off state (any of the states shown in FIGS. 4 to 7), and the water pump 8 is driven at a very low speed (for example, the minimum rotation speed). It was. By setting the three-way valve 40 to the shut-off state, the return flow path 10b is cut off, so that the water in the water-refrigerant heat exchanger 4 is reliably prevented from flowing out to the return flow path 10b. Further, by driving the water pump 8 at a slow speed, it is reliably prevented that the water in the water-refrigerant heat exchanger 4 flows backward to the forward flow path 10a side (the water pump 8 side). Therefore, the water in the water-refrigerant heat exchanger 4 does not flow into the return flow path 10b side or the forward flow path 10a side, and stops completely. For this reason, heat transfer from the refrigerant (hot gas) to water is reliably prevented inside the water refrigerant heat exchanger 4, and the refrigerant can be sent to the evaporator 6 while being reliably maintained at a high temperature. It becomes. Therefore, it can defrost efficiently and rapidly.

  Moreover, in this embodiment, not only the return flow path 10b but the upper flow path 10c and the lower flow path 10e are simultaneously cut off by setting the three-way valve 40 to the cut-off state during the defrosting operation. For this reason, the movement of the water in the hot water supply circuit 200 can be more reliably prevented, and the occurrence of heat exchange within the water refrigerant heat exchanger 4 can be more reliably prevented.

  Furthermore, in the heat pump type water heater 50 of the present embodiment, it is not necessary to add a new configuration (bypass passage, electromagnetic valve, etc.) to the refrigeration cycle circuit 100 for the defrosting operation, so that the cost can be reduced. Further, since the refrigeration cycle circuit 100 is not complicated, high reliability can be obtained. In addition, since the refrigerant circulation path does not change when the heating operation is switched to the defrosting operation, it is possible to suppress the generation of the sound of the refrigerant, the operation sound of the electromagnetic valve, and the like.

In the heat pump type hot water heater 50, when the defrosting operation is completed and the boiling operation is restarted, the heat energy (sensible heat) remaining in the water refrigerant heat exchanger 4 is effectively used for boiling. Therefore, it is desirable to control in the following order.
(1) The three-way valve 40 is switched to a state where the return flow path 10b communicates with the upper flow path 10c.
(2) The rotational speed of the water pump 8 is increased. At this time, the temperature sensor (not shown) detects the temperature of the high-temperature water coming out of the water-refrigerant heat exchanger 4, and the temperature of the high-temperature water coming out of the water-refrigerant heat exchanger 4 becomes a predetermined boiling temperature. The rotation speed of the water pump 8 is controlled.
(3) The fan 7 is operated to adjust the rotational speed of the compressor 3.

  By performing the control in the above order and restarting the boiling operation, the heat in the defrosting operation remaining in the water-refrigerant heat exchanger 4 can be reliably recovered and stored in the hot water storage tank 9. As a result, the energy efficiency is improved, the time required for adjusting the compressor 3 and the expansion valve 5 necessary for heating can be shortened, and the rotational speed of the water supply pump 8 can be increased quickly. . For this reason, it becomes possible to restart boiling operation at an early stage.

DESCRIPTION OF SYMBOLS 1 Heat pump unit 2 Hot water storage tank unit 3 Compressor 4 Water refrigerant | coolant heat exchanger 5 Expansion valve 6 Evaporator 7 Fan 8 Water supply pump 9 Hot water storage tank 10a Outward flow path 10b Return flow path 10c Upper flow path 10e Lower flow path 11 Control apparatus 13 System control device 15 Valve body 40 Three-way valve 50 Heat pump water heater 100 Refrigeration cycle circuit 200 Hot water supply circuit

Claims (3)

A refrigeration cycle circuit in which a compressor for compressing refrigerant, a water refrigerant heat exchanger for heating water by the refrigerant compressed by the compressor, an expansion valve, and an evaporator are connected in this order through a refrigerant flow path When,
A hot water storage tank, a water supply pump provided in the middle of a flow path for sending water taken from a lower part of the hot water storage tank to the water refrigerant heat exchanger, a three-way valve, and an outlet of water of the water refrigerant heat exchanger A hot water supply having a return flow path connecting the three-way valve, an upper flow path connecting the three-way valve and the upper part of the hot water storage tank, and a lower flow path connecting the three-way valve and the lower part of the hot water storage tank Water circuit,
Control means for controlling the refrigeration cycle circuit and the hot water supply circuit,
The three-way valve can be switched between a state in which the return channel communicates with the upper channel, a state in which the return channel communicates with the lower channel, and a state in which the return channel is blocked.
In the defrosting operation for defrosting the evaporator, the control means switches the three-way valve to shut off the return flow path and drives the water pump at a slow speed. Water heater. The three-way valve can be switched to a state of blocking the return channel, the upper channel, and the lower channel,
2. The heat pump hot water supply according to claim 1, wherein the control means switches the three-way valve to a state in which the return flow path, the upper flow path, and the lower flow path are each blocked during the defrosting operation. Machine.   When the control means ends the defrosting operation and restarts the boiling operation, the control means switches the three-way valve to a state in which the return flow path communicates with the upper flow path, and then the number of rotations of the water pump The heat pump type hot water heater according to claim 1 or 2, wherein the number of revolutions of the compressor is adjusted after that.

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