JP2007040590A - Heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation of heating efficiency caused by liquid accumulation occurring as a refrigerant flows into a heat pump circuit from the operating heat pump circuit when operation stops. <P>SOLUTION: The heat pump water heater is provided with a first heat pump circuit 2 having an evaporator 8b connected to a compressor 10b through a first water-refrigerant heat exchanger 6 and a first decompressor 7b, a direct water heating passage 3 for supplying supplied water heated by the first water-refrigerant heat exchanger 6 to a hot water supply port, a second heat pump circuit 4 including the evaporator 8b connected to the compressor 10b through a second water-refrigerant heat exchanger 11 and a second decompressor 7c, a heating circuit 5 for circulating hot water heated by the second water-refrigerant heat exchanger 11 with a heating source 12, and a switching means B for switching operation of the first heat pump circuit 2 and the second heat pump circuit 4. A valve of the second decompressor 7c is opened by a set amount during operation of the first heat pump circuit 2, and a valve 7b of the first decompressor is opened by a set amount during operation of the second heat pump circuit 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat pump water heater.

  As a conventional hot water supply device, for example, a hot water supply device that stores hot water obtained by burning fossil fuel in a large-capacity tank and uses the hot water stored in the tank during the day is known. According to such a hot water supply apparatus, for example, a sufficient amount of heat can be supplied even when operations such as hot water supply and heating are performed simultaneously. However, the combustion-type hot water supply apparatus has been decreasing in recent years because it may cause problems in exhaust gas treatment in addition to insufficient thermal efficiency. On the other hand, an electric water heater is known that uses late-night power with a low electricity bill, stores hot water heated by an electric heater in a large-capacity tank, and uses hot water in the tank during the day.

  On the other hand, in recent years, heat pump water heaters having higher energy efficiency than electric water heaters have begun to spread. This heat pump water heater operates the heat pump circuit using midnight power, and fills the tank with the heated water supply so that it can cover the hot water used during the day and the heat used for heating. I have to.

  For example, a heat pump water heater disclosed in Patent Document 1 operates a heat pump circuit using midnight power and stores hot water in a tank, like an electric water heater. When the amount of hot water is reduced (or the hot water temperature is lowered) and hot water having the set hot water temperature cannot be obtained, the heat pump circuit is operated again to replenish the hot water in the tank. During heating operation, the hot water in the tank is led to a heat exchanger installed in the heating tank and circulated, so that the hot water in the heating tank heated by this is passed to the radiator (heater). ing.

JP 2004-28483 A (FIG. 1)

  However, in the case of a method of storing a large amount of hot water in a tank as in Patent Document 1, the high heating efficiency of the heat pump circuit cannot be sufficiently exhibited. Also, a lot of heat is radiated from the surface of the tank, resulting in wasted energy, leading to a decrease in energy efficiency. Furthermore, with the increase in capacity of the tank, there is a problem that the installation area increases and the strength of the installation floor is required.

  In addition, in the technique of Patent Document 1, since the heating operation is performed using the hot water of the tank, the hot water may run out only by the hot water supply operation, and in addition, the occurrence of the hot water running is accelerated by performing the heating operation. there is a possibility. In addition, heat exchange between the hot water led from the tank and the circulating water for heating results in low heat exchange efficiency, and the return water temperature from the radiator also drops to the middle temperature range, disturbing the temperature distribution in the tank. There is a risk of generating a temperature range that is too low to be used for hot water supply.

  On the other hand, the first heat pump circuit and the second heat pump circuit sharing the compressor and the evaporator are connected so as to be switchable, for example, the hot water supply operation is performed by the first heat pump circuit, while the second heat pump circuit is operated. A heat pump circuit that performs heating operation is conceivable. According to this, in the water-refrigerant heat exchanger of each heat pump circuit, since heat can be directly exchanged between the water supply or the circulating water for heating and the refrigerant, high heating efficiency can be obtained.

  By the way, in such a heat pump circuit, for example, when the decompression device of the first heat pump circuit is opened and the heat pump circuit is operating, the decompression device of the second heat pump circuit is closed, and the second heat pump circuit The operation has stopped. However, since the second heat pump circuit communicates with the first heat pump circuit on the discharge side of the compressor, a part of the high-temperature and high-pressure refrigerant discharged from the compressor flows into the second heat pump circuit. However, it may be cooled and condensed by the second water refrigerant heat exchanger. That is, when the refrigerant flows into the second heat pump circuit and condenses, resulting in a liquid pool, the amount of refrigerant circulating in the first heat pump circuit decreases accordingly, so that the heating capacity is maintained. For example, the number of rotations of the compressor must be increased, which may cause a reduction in heating efficiency.

  An object of the present invention is to suppress a decrease in heating efficiency caused by a refrigerant flowing from a heat pump circuit in operation into a heat pump circuit in which the operation is stopped to cause a liquid pool.

  In order to solve the above problems, the present invention provides a first heat pump circuit having an evaporator connected to a compressor via a first water refrigerant heat exchanger and a first pressure reducing device, and a first water refrigerant. A second heat pump having a direct hot water supply path for supplying hot water heated by a heat exchanger to a hot water supply port, and an evaporator connected to the compressor via a second water refrigerant heat exchanger and a second decompression device A circuit, a heating circuit that circulates hot water heated by the second water-refrigerant heat exchanger with a heating source, and switching means for switching between the operation of the first heat pump circuit and the second heat pump circuit, During operation of the first heat pump circuit, a set amount of the valve of the second decompression device is opened.

  Thus, during operation of the first heat pump circuit, the refrigerant flowing into the second heat pump circuit by opening a set amount of the valve of the second decompression device is the second water refrigerant heat exchanger, the second It returns to the 1st heat pump circuit through the decompression device. As a result, the refrigerant flowing into the second heat pump circuit is restrained from the liquid pool due to the retention, so that the decrease in the amount of refrigerant in the first heat pump circuit can be suppressed, and the decrease in heating efficiency can be suppressed. Further, during operation of the second heat pump circuit, the same effect can be obtained by opening a set amount of the valve of the first pressure reducing device.

  Moreover, it is preferable that a 1st water refrigerant | coolant heat exchanger has the refrigerant | coolant flow path of the 3rd heat pump circuit independent of the 1st and 2nd heat pump circuit. According to this, a hot water supply and heating operation can be performed simultaneously by making a 3rd heat pump circuit into the heat pump circuit only for hot water supply, and switching a 1st heat pump circuit to a 2nd heat pump circuit as needed.

  According to the heat pump water heater of the present invention, it is possible to suppress a decrease in heating efficiency due to liquid pooling.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram showing an example of a heat pump water heater to which the present invention is applied. FIG. 2 is an enlarged configuration diagram showing a part of FIG.

  The heat pump water heater of the present embodiment circulates the hot water supply circuit 3 (not including a bathtub 16 described later) for supplying hot water heated by the heat pump circuits 1 and 2 and the hot water heated by the heat pump circuit 4. A heating circuit 5 that performs heating, heat pump control units A and B that control operation of the heat pump circuits 1, 2, and 4, and a hot water supply control unit C that controls the hot water supply circuit 3 are provided in a single container. It is stored.

  First, the heat pump circuit 1 constitutes a closed circuit in which a first water refrigerant heat exchanger 6, a decompression device 7a, an evaporator 8a, and a compressor 10a are sequentially connected by a refrigerant pipe, and the heat pump circuit 2 has a first water A closed circuit in which the refrigerant heat exchanger 6, the decompression device 7b, the evaporator 8b, and the decompression device 10b are sequentially connected by a refrigerant pipe is configured.

  The decompression devices 7a and 7b radiate heat from the first water refrigerant heat exchanger 6 and decompress the high-pressure refrigerant whose temperature has been lowered. The valve opening degree can be freely controlled by commands from the heat pump control units A and B. It can be adjusted. The evaporators 8a and 8b function as air refrigerant heat exchangers that exchange heat between air and refrigerant by taking in outdoor air by the fans 9a and 9b and evaporating low-temperature and low-pressure refrigerant, respectively. .

  The compressors 10a and 10b are rotated from a low speed (for example, 2000 rotations / minute) to a high speed (for example, 8000 rotations / minute) by PWM control, voltage control (for example, PAM control) and rotation speed control combining them. Can be freely controlled. In particular, when supplying hot water directly from the first water-refrigerant heat exchanger 6, the heat pump controllers A and B operate with the compressors 10a and 10b set at a high speed.

  The first water-refrigerant heat exchanger 6 includes a refrigerant-side heat transfer tube and a water supply-side heat transfer tube, and the refrigerant of the heat pump circuits 1 and 2 flows through the refrigerant-side heat transfer tubes 6a and 6b, respectively. The side heat transfer tubes 6c and 6d are respectively supplied with water from a bath reheating circuit and a direct hot water supply circuit (or a bath hot water circuit) described later. In addition, the flow direction of the refrigerant flowing in the pipe of the refrigerant side heat transfer tube and the flow direction of the water supply flowing in the pipe of the water supply side heat transfer tube are opposite to each other.

  The hot water supply circuit 3 includes a direct hot water supply path, a tank hot water storage circuit, a bath hot water filling circuit, and a bath reheating circuit.

  The direct hot water supply path includes a water supply source (not shown), a pressure reducing check valve 13, a water supply path for sequentially connecting the first water refrigerant heat exchanger 6 with a water supply pipe 15, a first water refrigerant heat exchanger 6, and a mixing valve 17. The flow rate adjusting valve 19 and a hot water supply path that sequentially connects hot water supply ports (not shown) through a hot water supply pipe 21 are provided. A water pipe 22 (bypass circuit) branched from the water supply pipe 15 is connected to the downstream side of the mixing valve 17 of the hot water supply pipe 21, whereby hot water and water supplied by the first water refrigerant heat exchanger 6 are connected. The water branched and supplied from the path can be mixed and adjusted to a predetermined hot water temperature set by the hot water controller C. The adjustment of the hot water supply temperature controls the mixing amount of the water supply by adjusting the valve opening degree of the mixing valve 23 installed in the water pipeline 22. The flow rate adjusting valve 19 controls the flow rate so that the hot water supply amount does not exceed the planned total amount.

  In addition, a tank 25 is provided in parallel with the first water refrigerant heat exchanger 6 between the water supply path and the hot water supply path, and the top of the tank 25 is connected to the hot water supply pipe 21 via the mixing valve 17. On the other hand, the bottom is connected to the water supply pipe 15. That is, by mixing the hot water heated by the first water-refrigerant heat exchanger 6 and the hot water of about 60 to 90 ° C. stored in the tank 25 directly into the hot water supply path through the mixing valve 17. For example, before the heat pump circuit 1 is started, hot water having a set hot water supply temperature (for example, 35 to 60 ° C.) can be supplied. In the heat pump water heater of the present embodiment, for example, for a short time before the heat pump circuit 1 is started up, the low temperature water that has flowed through the first water refrigerant heat exchanger 6 and the hot water in the tank 25 are mixed, and the set temperature is reached. Hold it in the hot water supply. And after the heat pump circuit 1 is started and the operation is stabilized, the use of the hot water in the tank 25 is stopped, and the hot water heated by the first water refrigerant heat exchanger 6 can be directly supplied to the use terminal. The capacity of the tank 25 can be reduced.

  The tank hot water storage circuit mixes the path connecting the bottom of the tank 25 to the water supply port of the first water refrigerant heat exchanger 6 via the circulation pump 27 and the hot water outlet of the first water refrigerant heat exchanger 6. A closed circuit having a path connected to the top of the tank 25 via the valve 17 is provided. The tank 25 is provided with temperature sensors 29, 31, and 33 from the top to the bottom. For example, when hot water having a temperature equal to or higher than the set temperature in the tank 25 becomes less than a set amount, the circulation pump 27 is operated to The hot water extracted from the tank is heated by the first water-refrigerant heat exchanger 6, and the heated water is returned from the top into the tank 25, whereby the tank 25 is boiled back.

  The hot water bathing circuit includes a water supply source (not shown), a pressure reducing check valve 13, a water supply path for sequentially connecting the first water refrigerant heat exchanger 6 with a water supply pipe 15, a first water refrigerant heat exchanger 6, and a mixing valve. 17, a flow rate adjusting valve 19, a pouring electromagnetic valve 35, a circulation pump 37, and a hot water supply path for sequentially connecting the bathtub 16 with water pipes.

  The bath reheating circuit is a closed circuit in which the bathtub 16, the circulation pump 37, the pouring solenoid valve 35, the first water refrigerant heat exchanger 6, and the bathtub 16 are connected by a water pipe.

  On the other hand, the heat pump circuit 4 shares the compressor 10b and the evaporator 8b with the heat pump circuit 2, and has a configuration in which the discharge side of the compressor 10b and the entrance side of the evaporator 8b are bypassed. That is, the heat pump circuit 4 is a closed circuit in which the compressor 10b, the second water refrigerant heat exchanger 11, the decompression device 7c, and the evaporator 8b are sequentially connected by the refrigerant pipe. The second water refrigerant heat exchanger 11 includes a refrigerant side heat transfer tube 11a and a water supply side heat transfer tube 11b. The refrigerant of the heat pump circuit 4 flows through the refrigerant side heat transfer tube 11a, and the water supply side heat transfer tube 11b passes through the refrigerant. The circulating water of the heating circuit 5 flows.

  The heating circuit 5 is a closed circuit in which the second water-refrigerant heat exchanger 11, the heating panel 12, and the circulation pump 14 are sequentially connected by water piping.

  Further, in the heat pump water heater of the present embodiment, in addition to the temperature sensors 29, 31, 33 of the tank 25 described above, a flow rate sensor 41 for detecting the feed water flow rate, a temperature sensor 43 for detecting the feed water temperature, and the first water refrigerant. A temperature sensor 44 that detects the temperature of the water discharged from the heat exchanger 6, and a temperature sensor that detects the temperature of the mixed water of the water supplied from the tank 25 and the water supplied from the first water-refrigerant heat exchanger 6. 45, a temperature sensor 47 that detects the final hot water supply temperature, temperature sensors 51a and 51b that detect intermediate temperatures of the evaporators 8a and 8b, temperature sensors 53a and 53b that detect refrigerant suction temperatures of the compressors 10a and 10b, and heating Each part is provided with a thermistor 61 for detecting the circulating water temperature of the circuit 5.

  The heat pump control units A and B correspond to, for example, the heat pump circuit 1 and the heat pump circuits 2 and 4, respectively. The heat pump circuits 1 and 2 are based on the operation / setting of the hot water remote control, the heating remote control, and the detection values of the sensors. , 4 and the rotation speed control of the compressors 10a and 10b. The hot water supply control unit C controls, for example, the mixing valves 17 and 23, the flow rate adjustment valve 19 and the like based on the detection values of the sensors.

  The heat pump circuits 1, 2 and 4, the hot water supply circuit including the tank 25, and other devices other than the bathtub 16 and the heating panel 12 are all housed in a box (not shown).

  In the heat pump water heater configured as described above, the operation of each part when the use terminal is used will be described.

  When hot water supply is started from the use terminal (hot water supply port), water supplied from a water supply fitting (not shown) due to water pressure flows through the water supply pipe 15 via the pressure reducing check valve 13. At this time, when the flow sensor 41 detects water supply, the operation of the compressors 10a and 10b is started by the heat pump controllers A and B, and the operation of the heat pump circuits 1 and 2 is started. When the water supplied by the water pressure flows into the first water-refrigerant heat exchanger 6, the hot water heated to a predetermined temperature is discharged by heat exchange, and directly from the use terminal via the mixing valve 17 and the flow rate adjusting valve 19. Hot water is supplied.

  Until the heat pump circuits 1 and 2 are started up, the temperature of the hot water heated by the first water-refrigerant heat exchanger 6 is lower than the set hot water temperature, so the hot water stored in the tank 25 is mixed. By mixing a predetermined amount by the valve 17, the hot water temperature is adjusted to be close to the hot water supply temperature. Here, the hot water stored in the tank 25 by opening the inlet of the mixing valve 17 on the tank 25 side is pushed out of the tank 25 from the top by the water pressure of tap water flowing into the tank 25 from the bottom. It is. Thus, in the initial stage of operation, the amount of hot water supplied from the tank 25 is large, and the amount of hot water supplied through the first water refrigerant heat exchanger 6 is small (mixing operation mode). Therefore, by reducing the amount of hot water supplied to the first water-refrigerant heat exchanger 6, hot water at a set hot water supply temperature (for example, 35 to 60 ° C.) can be supplied more quickly.

  In this mixing operation mode, for example, when the hot water temperature of the use terminal detected by the temperature sensor 47 is equal to or higher than the set temperature, the mixing valve 23 is opened and water is mixed from the water line 22 to reach the set temperature. Adjusted.

  When the operation is continued in this state, the heat pump circuits 1 and 2 start to stabilize gradually, the temperature of the hot water discharged from the first water refrigerant heat exchanger 6 also becomes high, and the tank 25 and the first water refrigerant heat The mixing valve 17 for mixing the hot water supplied from the exchanger 25 gradually narrows down the hot water supply from the tank 25. And when the hot water temperature from the 1st water refrigerant | coolant heat exchanger 6 turns into preset temperature, the inlet by the side of the tank 25 of the mixing valve 17 is fully closed, and only the hot water heated by the heat pump circuits 1 and 2 is used. It is controlled to supply hot water to the terminal in use (instant water heating mode).

  In order to supply hot water to the use terminal at the set temperature at this time, based on the temperature detected by the temperature sensor 45, the hot water supplied from the first water refrigerant heat exchanger 6 through the mixing valve 17 and the water conduit 22 are used. The mixing ratio of the feed water supplied through the mixing valve 23 is adjusted. That is, water is mixed directly into the hot water supply path, bypassing the water refrigerant heat exchanger 6 and the tank 25. This path is called a bypass circuit. As a result, hot water adjusted to the set temperature is supplied to the use terminal. In particular, when the required hot water supply amount or the required temperature decreases, the hot water discharged from the first water-refrigerant heat exchanger 6 may become higher than the set temperature. For this reason, by adjusting the mixing valve 23 and appropriately adjusting the mixing amount of the water supply, hot water at the set temperature can be quickly supplied (water mixing mode). In consideration of efficiency, it is preferable to control the heating capacity of the water refrigerant heat exchanger 6 by controlling the number of rotations of the compressor so that water is not mixed as much as possible, but it is possible to improve responsiveness by mixing water. it can.

  On the other hand, in the boil-back operation in the tank 25, the water temperature on the outlet side of the first water-refrigerant heat exchanger 6 is detected by the temperature sensor 44 while the heat pump circuits 1 and 2 are operated, and the detected temperature is a predetermined temperature, That is, when the hot water storage temperature is reached, the circulation pump 27 is operated. Thereby, in the tank hot water storage circuit, the water accumulated in the lower part of the tank 25 is extracted from the tank 25 and guided to the first water refrigerant heat exchanger 6 and heated to a predetermined temperature, and then the mixing valve 17. Through the top of the tank 25 and returned to the tank 25 again.

  Here, when the temperature of the hot water discharged from the first water / refrigerant heat exchanger 6 is detected by the temperature sensor 44, the rotation speeds of the compressors 10 a and 10 b are adjusted so that the detected temperature becomes the hot water storage temperature of the tank 25. The discharge flow rate of the circulation pump 27 is controlled. Then, when the completion of the boiling of the tank 25 is detected by the temperature sensor 33 at the bottom of the tank 25, the boil-back operation in the tank 25 is finished and a standby state is entered.

  In addition, when filling the bathtub 16 with hot water, the same operation as described above (mixing operation mode, instantaneous boiling mode, water mixing mode) is performed in the bath hot water circuit, and the pouring solenoid valve 35 is opened by a predetermined amount. Then, hot water filling operation is performed. Further, when reheating the bathtub 16, in the bath reheating circuit, the circulation pump 37 is operated, and the bathtub water extracted from the bathtub 16 is guided to the first water / refrigerant heat exchanger 6 to perform heat exchange and heating. The returned hot water is returned to the bathtub 16 to perform a chasing operation.

  Next, the heating operation using the heat pump water heater of this embodiment will be described. As described above, in the present embodiment, by providing the heat pump circuit 2 and the heat pump circuit 4 that share the compressor 10b and the evaporator 8b in a switchable manner, for example, a hot water supply operation and a heating operation can be switched freely. That is, when there is a request for hot water supply and heating from the use terminal side, hot water supply is performed by operating the heat pump circuit 1 and heating is performed by operating the heat pump circuit 4, respectively.

  Here, when switching between the hot water supply operation and the heating operation, for example, when a request for the heating operation is received while the heat pump circuit 2 is in operation, the valve of the decompression device 7b is fully closed by the command of the heat pump control units A and B, and the decompression is performed. The valve of the device 7c is opened. As a result, the refrigerant (dotted arrow in FIG. 2) that has been circulating in the heat pump circuit 2 until then circulates in the heat pump circuit 4 (solid arrow in FIG. 2). Then, when a request to change the heating temperature is received from the use terminal during the heating operation, for example, the discharge flow rate of the circulation pump 14 or the rotation speed of the compressor 10b is adjusted based on the detected temperature of the thermistor 61. Thus, the heating temperature of the heating panel 12 can be adjusted.

  By the way, for example, in the hot water supply operation, when the heat pump circuit 2 is operated and the heat pump circuit 4 is stopped, a part of the high-temperature and high-pressure refrigerant discharged from the compressor 10b is a refrigerant pipe on the discharge side of the compressor 10b. May flow into the refrigerant pipe of the heat pump circuit 4 formed by branching. That is, the refrigerant that has flowed into the refrigerant pipe of the heat pump circuit 4 may be condensed, liquefied, and accumulated in the second water refrigerant heat exchanger 11 disposed on the entry side of the decompression device 7c, for example. Thus, when a refrigerant | coolant is accumulate | stored in the heat pump circuit 4, the circulation amount of the refrigerant | coolant in the heat pump circuit 2 will reduce, and a heating capability will fall. In order to compensate for the decrease in the refrigerant amount, it is conceivable to increase the rotational speed of the compressor 10b. However, according to this, the heating efficiency of the heat pump circuit 2 is reduced. Also, in the heating operation, the same problem as in the hot water supply operation occurs, the amount of refrigerant circulating in the heat pump circuit 4 decreases, and the heating capacity decreases.

  Therefore, in the present embodiment, for example, in the hot water supply operation, during operation of the heat pump circuit 2, the heat pump control unit B or the like controls the valve of the decompression device 7c of the heat pump circuit 4, that is, the expansion valve to open a set amount. ing. According to this, the refrigerant that has leaked from the heat pump circuit 2 into the refrigerant pipe of the heat pump circuit 4 flows through the refrigerant pipe via the second water refrigerant heat exchanger 11 and the decompression device 7c without causing a liquid pool. Then, it is returned to the heat pump circuit 2 again. For this reason, the reduction | decrease of the refrigerant | coolant amount which circulates through the heat pump circuit 2 can be suppressed, the increase in the rotation speed of the compressor 10b can be suppressed, and a hot water supply operation can be performed efficiently. In the heating operation, similarly to the above, during the operation of the heat pump circuit 4, the decompression device 7b is controlled so as to release a set amount, thereby suppressing the decrease in the amount of refrigerant circulating in the heat pump circuit 4, and the heating operation. It can be done efficiently. Needless to say, the refrigerant circulation rate can be adjusted by increasing or decreasing the opening of the decompression device in the operating heat pump circuit.

  Here, in the two switchable heat pump circuits sharing the compressor and the evaporator, for example, when operating one of the hot water supply heat pump circuits, the opening amount of the decompression device (expansion valve) of the other heating heat pump circuit Will be described with reference to the drawings.

  FIG. 3 shows the expansion valve opening (horizontal axis) of the decompression device 7c of the heating heat pump circuit, the heating capacity of the hot water supply heat pump circuit, the refrigerant circulation rate, and the compressor rotation speed (vertical) during operation of the hot water supply heat pump circuit. 4 is a diagram showing the relationship between the expansion valve opening (horizontal axis) of the decompression device 7b of the hot water supply heat pump circuit and the heating capacity of the heating heat pump circuit during operation of the heating heat pump circuit. It is a figure which shows the relationship between refrigerant | coolant circulation amount and compressor rotation speed (vertical axis).

  As apparent from FIG. 3, in order to maintain the heating capacity (Q) of the hot water supply heat pump circuit, the expansion valve opening degree of the heating heat pump circuit is set to about 5% with respect to the fully opened 100%. Efficiency) can be maximized. If the expansion valve opening is smaller than 5%, the refrigerant flowing into the heating heat pump circuit side is not supplied to the hot water supply heat pump circuit side, so that the refrigerant condenses in the water refrigerant heat exchanger of the heating heat pump circuit. Puddle occurs. For this reason, the refrigerant circulation amount (Gw) of the hot water supply heat pump circuit decreases, and in order to maintain the target heating capacity, the compressor rotational speed (N) must be increased, and the COP decreases. On the other hand, if the expansion valve opening is larger than 5%, excess refrigerant flows into the water / refrigerant heat exchanger of the heating heat pump circuit, and the required condensation heat (condensation enthalpy) of the hot water supply heat pump circuit decreases. Heat loss occurs. For this reason, the refrigerant circulation amount (Gw) of the hot water supply heat pump circuit decreases, and in order to maintain the target heating capacity, the compressor rotational speed (N) must be increased, and the COP decreases. Similarly, as is apparent from FIG. 4, the COP can be maximized by setting the expansion valve opening degree of the hot water supply heat pump circuit to about 5%. However, considering a certain width (± 2%), the expansion valve opening is preferably about 3 to 7%.

  As described above, according to the heat pump water heater of this embodiment, during operation of one heat pump circuit that can be switched, the valve of the decompression device of the other heat pump circuit is opened by a set amount (for example, 5% opening). By doing so, the refrigerant flowing into the other heat pump circuit side can be recovered to the one heat pump circuit side. As a result, an appropriate refrigerant circulation amount can be secured in one of the heat pump circuits, and the efficiency of hot water supply and heating operation can be maintained high.

  In addition, the heat pump water heater of this embodiment includes a heat pump circuit that can be switched between a hot water supply operation and a heating operation, and a heat pump circuit dedicated to the hot water supply operation, so that the hot water supply operation and the heating operation can be performed simultaneously. In addition, the hot water supply and the heating operation efficiency can be kept high without causing hot water to run out.

  Moreover, although the heat pump water heater of this embodiment is provided with the tank which stores hot water, it is good also as a structure which supplies hot water only with a direct hot water supply system, without equip | installing a tank.

Note that the refrigerant is carbon dioxide CO _2, by a refrigeration cycle which becomes supercritical at the high pressure side, the temperature of the hot water to the hot water storage tank can be a high temperature of 60 to 90 ° C..

It is a whole lineblock diagram showing an example of a heat pump water heater to which the present invention is applied. It is a block diagram which expands and shows a part of FIG. The figure which shows the relationship between the expansion valve opening degree (horizontal axis) of the heat pump circuit for heating, the heating capacity of the heat pump circuit for hot water supply, the amount of refrigerant circulation, and the rotation speed of the compressor (vertical axis) during operation of the heat pump circuit for hot water supply It is. The figure which shows the relationship between the expansion valve opening degree (horizontal axis) of the heat pump circuit for hot water supply, the heating capability of the heating pump circuit, the refrigerant circulation amount, and the compressor rotation speed (vertical axis) during the operation of the heating heat pump circuit It is.

Explanation of symbols

1, 2, 4 Heat pump circuit 5 Heating circuit 6 First water refrigerant heat exchanger 7a, 7b, 7c Pressure reducing device 8a, 8b Evaporator 10a, 10b Compressor 11 Second water refrigerant heat exchanger 12 Heating panel 14, 27, 37 Circulation pump 15 Water supply pipe 17, 23 Mixing valve 19 Flow rate adjustment valve 21 Hot water supply pipe 25 Tank A, B Heat pump controller C Hot water controller

Claims (7)

A first heat pump circuit having an evaporator connected to a compressor via a first water refrigerant heat exchanger and a first pressure reducing device, and hot water heated by the first water refrigerant heat exchanger A direct hot water supply path for supplying to the mouth, a second heat pump circuit having the evaporator connected to the compressor via a second water refrigerant heat exchanger and a second pressure reducing device, and the second water A heating circuit that circulates hot water heated by the refrigerant heat exchanger with a heating source; and a switching unit that switches operation of the first heat pump circuit and the second heat pump circuit,
During operation of the first heat pump circuit, a set amount of the valve of the second pressure reducing device is opened, and during operation of the second heat pump circuit, a set amount of the valve of the first pressure reducing device is opened. A heat pump water heater characterized by A first heat pump circuit having an evaporator connected to a compressor via a first water refrigerant heat exchanger and a first pressure reducing device, and hot water heated by the first water refrigerant heat exchanger A direct hot water supply path for supplying to the mouth, a second heat pump circuit having the evaporator connected to the compressor via a second water refrigerant heat exchanger and a second pressure reducing device, and the second water A heating circuit that circulates hot water heated by the refrigerant heat exchanger with a heating source,
When operating the first heat pump circuit without operating the heating circuit, the valve of the second pressure reducing device is opened by a set amount, and the second heat pump is not operated without operating the first heat pump circuit. When operating the circuit, a heat pump water heater having control means for controlling each of the pressure reducing devices so as to open the valve of the first pressure reducing device by a set amount. When the first heat pump circuit is operated without operating the heating circuit, the control means adjusts the refrigerant circulation amount by increasing / decreasing the opening of the first pressure reducing device, and / or 3. The refrigerant circulation amount is adjusted by increasing or decreasing an opening degree of the second decompression device when the second heat pump circuit is operated without operating the first heat pump circuit. The heat pump water heater described. The heat pump water heater according to any one of claims 1 to 3, wherein the set amount when the valve of the first or second pressure reducing device is opened is a valve opening of 3 to 7%. . 5. The heat pump water heater according to claim 4, wherein the first water refrigerant heat exchanger has a refrigerant flow path of a third heat pump circuit independent of the first and second heat pump circuits. 6. The heat pump water heater according to claim 5, further comprising a tank capable of mixing hot water stored in the direct hot water supply path and a bypass circuit capable of mixing water supplied. . The heat pump water heater according to claim 6, wherein the refrigerant circulating in each of the heat pump circuits is carbon dioxide, and is a refrigeration cycle that becomes supercritical on the high-pressure side.

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