JP3917581B2 - Heat pump water heater - Google Patents

Description

  The present invention uses a heat pump cycle in which a compressor, a hot water supply heat exchanger, an expansion valve, and an evaporator are connected by piping, carbon dioxide is used as a refrigerant, and the compressor is operated in a state exceeding the critical pressure on the high pressure side. The present invention relates to a heat pump water heater.

Conventionally, various hot water supply devices using a heat pump cycle have been proposed. For example, hot water heated by a heat exchanger using a heat pump cycle is stored in a hot water storage tank, and the stored hot water and a heat insulation circuit for keeping the bathtub warm A hot water supply apparatus having an external heat exchanger that exchanges heat with hot water flowing through the water has been proposed (see, for example, Patent Document 1).
JP 2001-263812 A (Claim 1 and FIG. 1)

However, in the conventional heat pump water heater, the water at the bottom of the hot water storage tank is fed to the heat exchanger by the water pump for boiling water, the heat is exchanged by the heat exchanger, and then the heated hot water is placed in the upper part of the hot water storage tank. In the case of so-called medium temperature water whose temperature at the bottom of the hot water storage tank is, for example, about 50 ° C. when performing the returning water boiling operation, it becomes difficult to absorb heat from the outside air in the evaporator of the heat pump cycle, so-called COP (cooling capacity and compression) In order to carry out bathing, the hot water is drawn from the upper part of the hot water storage tank and heat is exchanged with an external heat exchanger, and then the cooled hot water is stored in the hot water storage tank. When returning to the bottom of the tank, the capacity of the external heat exchanger is low, and the heat of the heat pump circuit during the boiling operation is lowered because the hot water is not sufficiently exchanged and medium temperature hot water is returned to the bottom of the tank. Bet there was. In particular, in the case of a carbon dioxide refrigerant, the pressure on the high pressure side may increase to the extent that the operation of the equipment is hindered by the operation of the compressor.
Moreover, in order to avoid such a situation, it was necessary to prepare a large external heat exchanger having a high heat exchange capability.

The present invention solves such problems, and can reduce the temperature of hot water that is exchanged with an external heat exchanger and returned to a hot water storage tank when bathing, and can realize space saving. The purpose is to provide.
It is another object of the present invention to provide a heat pump hot water supply apparatus that reduces the size and weight of the external heat exchanger and simplifies the installation work of the external heat exchanger.

The heat pump hot water supply apparatus of the present invention according to claim 1 has a compressor and a radiator, uses carbon dioxide as a refrigerant, and operates with a heat pump circuit operating in a state exceeding a critical pressure on the high pressure side by the compressor. A hot water storage circuit for heating water in the lower part of the tank to the upper part of the hot water storage tank after being heated by the radiator, and hot water cooled by the external heat exchanger by introducing the hot water in the hot water storage tank into the external heat exchanger A heat pump comprising a primary side water supply circuit for returning to a hot water storage tank, and a secondary side water supply circuit for introducing the water in the bathtub into the external heat exchanger and returning the hot water heated by the external heat exchanger into the bathtub. A hot water supply device using a plate-type heat exchanger as the external heat exchanger, deriving hot water to be introduced into the external heat exchanger from an upper part of the hot water storage tank, and warm water cooled by the external heat exchanger in front And introducing from the lower portion of the hot water storage tank.
According to a second aspect of the present invention, in the heat pump hot water supply device according to the first aspect, the plate heat exchanger is caused to flow from the upper part to the lower part in the water supply direction of the primary side water supply circuit, and the secondary side water supply circuit. The water supply direction is arranged so as to flow from the lower part to the upper part.
According to a third aspect of the present invention, in the heat pump hot water supply device according to the first or second aspect, a water supply pump is provided in the secondary side water supply circuit, and the water pump is arranged upstream of the plate heat exchanger. It was set up.
According to a fourth aspect of the present invention, in the heat pump hot water supply apparatus according to the first, second, or third aspect, a heat exchanger is provided on a side surface of the hot water storage tank, and the plate heat exchanger is attached to the heat exchanger. It is characterized by.
According to a fifth aspect of the present invention, in the heat pump hot water supply apparatus according to any one of the first to fourth aspects, a display unit indicating a vertical direction is provided on a surface of the plate heat exchanger, and the plate heat exchanger is Covering with a heat insulating material, providing a door or an opening in the heat insulating material, and making the door or the opening correspond to the position of the display unit.

According to the present invention, since the lower part of the hot water storage tank can be kept at a low temperature even when bathing is performed in a state where a considerable amount of heat is accumulated in the hot water storage tank, The temperature can be lowered, and the heat pump circuit can be operated at a high COP.
Further, the external heat exchanger can be reduced in size, and the installation space can be saved.
Also, by supplying hot water from the primary side water supply circuit from the top and low temperature water from the secondary side water supply circuit from the bottom, the upper part of the plate heat exchanger is placed in a higher temperature state to increase heat exchange efficiency. On the other hand, it is possible to lower the temperature of the hot water returned to the hot water storage tank by lowering the temperature of the lower part.
Moreover, it can reduce that the foreign material from a bathtub is blocked by the plate type heat exchanger by arrange | positioning a water pump to the upstream of a plate type heat exchanger.
Moreover, since the installation work of the heat exchanger can be simplified and the vertical direction of the plate heat exchanger can be installed without making a mistake, the assemblability of the tank unit can be improved.

The heat pump hot water supply apparatus according to the first embodiment of the present invention uses a stacked hot water storage tank as a hot water storage tank, uses a plate heat exchanger as an external heat exchanger for bathing, and introduces it into the external heat exchanger. Hot water is led out from the upper part of the hot water storage tank, and hot water cooled by an external heat exchanger is introduced from the lower part of the hot water storage tank. According to the present embodiment, a stacked hot water storage tank is used as a hot water storage tank, a plate heat exchanger having a high heat exchange amount is used, and sufficient heat exchange is performed with this plate heat exchanger, and the cooled hot water is supplied. By returning to the lower part of the hot water storage tank, the lower part of the hot water storage tank can be kept at a low temperature even when a considerable amount of heat is accumulated in the hot water storage tank. Therefore, the temperature of the hot water introduced into the radiator of the heat pump circuit can be lowered, and the heat pump circuit can be operated with high COP (efficiency).

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a circuit configuration diagram of an embodiment of a heat pump water heater according to the present invention. The heat pump water heater according to the present embodiment includes a heat pump circuit 10 and a tank unit 20. The heat pump circuit 10 is configured by connecting a compressor 11, a radiator 12, an expansion valve 13, and an evaporator 14 in order by a pipe, and is housed in a housing. The heat pump circuit 10 preferably uses carbon dioxide, which is a natural refrigerant, as a refrigerant, and operates in a state where the critical pressure is exceeded on the high pressure side.
The tank unit 20 includes a hot water storage tank 22 and an external heat exchanger 23 for bathing in a housing 21. The hot water storage tank 22 is a stacked hot water storage tank in which high temperature water is stored in the upper part and low temperature water is stored separately in each temperature layer, and the external heat exchanger 23 is a plate type in which a plurality of heat transfer plates are stacked. Use the heat exchanger vertically. The external heat exchanger 23 is a water-water heat exchanger in which a water flow is opposed to each other. A water supply port 231 and a water discharge port 233 are provided in the upper portion, and a water discharge port 232 and a water supply port 234 are provided in the lower portion. The water supplied from 231 is drained from the lower drainage port 232, and the water supplied from the lower water supply port 234 is drained from the upper drainage port 233.
The hot water storage tank 22 is provided with a water outlet 221 and a water inlet 223 in the upper part, and a water inlet 222 and a water outlet 224 in the lower part.

Hot water is supplied to the upper water supply port 231 of the external heat exchanger 23 from the water outlet port 221 of the upper part of the hot water storage tank 22 through the pipe 24, and after exchanging heat with the external heat exchanger 23, the lower water outlet 232. Drained from. The drained water is fed into the hot water storage tank 22 from the water inlet 222 at the lower part of the hot water storage tank 22 through the pipe 26 by the tank warm water water supply pump 25. A primary side water supply circuit of the external heat exchanger 23 is formed by the pipe 24, the external heat exchanger 23, the tank hot water use water supply pump 25 and the pipe 26.
On the other hand, hot water from the bathtub 31 is supplied to the water supply port 234 at the lower part of the external heat exchanger 23 through the pipe 33 by the water supply pump 32, and is heated and heated by the external heat exchanger 23. Become. Thereafter, the hot water drained from the upper drainage port 233 is returned to the bathtub 31 through the pipe 34. A secondary side water supply circuit of the external heat exchanger 23 is formed by the pipe 33, the water supply pump 32, the external heat exchanger 23 and the pipe 34.
The water from the water outlet 224 at the lower part of the hot water storage tank 22 is supplied to the radiator 12 of the heat pump circuit 10 through the pipe 17 by the water heater 16 and heated by the radiator 12, and then the pipe 18. The water is then returned to the hot water storage tank 22 from the water inlet 223 at the top of the hot water storage tank 22. The hot water supply pump 16, the piping 17, the radiator 12, and the piping 18 constitute a hot water storage circuit. When the hot water in the hot water storage tank 22 is used for hot water supply (a hot water supply circuit is not shown), the water supply valve 27 is opened to supply city water from the water outlet 224 of the hot water storage tank 22.

  2A and 2B are conceptual diagrams of a plate heat exchanger used as the external heat exchanger 23, where FIG. 2A is a front view and FIG. 2B is a side view. FIG. 3 is a sectional view of a tank unit in an embodiment of a heat pump hot water supply apparatus according to the present invention, where (a) is a plan view and (b) is a side view. The plate heat exchanger 41 is configured by laminating a plurality of heat transfer plates 42 alternately with a foil-like copper brazing material and melt-bonding them by brazing in a high-temperature vacuum furnace. A mounting bracket 43 having a screw hole 44 is attached to the back surface of the plate heat exchanger 41, and is attached by spot welding to a dead space formed on the outer periphery of the hot water storage tank as shown in FIGS. 3 (a) and 3 (b). It is attached to the heat exchanger 45 for sheet metal by screwing or the like. Therefore, the pipes 24 and 26 that connect the hot water storage tank 22 and the plate heat exchanger 41 can be shortened, and the tank unit 20 can be made compact. In addition, the plate heat exchanger 41 can be easily attached to the tank unit 20.

FIG. 4 (a) is a front view when the plate heat exchanger in the embodiment of the heat pump hot water supply apparatus according to the present invention is covered with a heat insulating material, and FIG. 4 (b) shows the door from the state of FIG. 4 (a). It is a front view when it opens. The plate heat exchanger 41 used as the external heat exchanger 23 is used vertically as described with reference to FIG. 1, but the vertical direction during use is strictly set based on the relationship between introduction and derivation of water. On the contrary, the heat exchange capability is greatly reduced. Therefore, as shown in FIG. 4B, characters and symbols 47 that indicate the vertical direction are written on the front surface of the plate heat exchanger 41. By the way, the plate heat exchanger 41 is usually used by being entirely covered with a heat insulating material 46 in order not to reduce the heat exchange amount.
When the plate heat exchanger 41 is covered with the heat insulating material 46, characters and symbols 47 are hidden by the heat insulating material 46. Therefore, as shown in FIG. 4A, a door 48 is formed by making a cut at a position corresponding to the letters and symbols 47 of the heat insulating material 46. When the door is opened, as shown in FIG. 4B, the letters and symbols 47 written on the front surface of the plate heat exchanger 41 can be confirmed. The vertical position can be confirmed when attaching to the.

  FIG. 5 shows an example in which an opening such as a window 49 is formed instead of the door 48 of FIG. In the case where the window 49 is formed, there is no heat insulating material 46 only in that portion, but the size of the window 49 may be a size that can confirm the letters and symbols 47, which affects the heat insulating effect of the plate heat exchanger 41. Will not affect.

Next, the operation will be described. In FIG. 1, the heat pump circuit 10 is operated by the hot water storage operation signal, the refrigerant is compressed by the compressor 11 to become high temperature and pressure, cooled by the radiator 12, decompressed by the expansion valve 13, and absorbs heat from the atmosphere by the evaporator 14. Evaporates and returns to the compressor 11. On the other hand, water is supplied to the radiator 12 from the water outlet port 224 in the lower part of the hot water storage tank 22 by the hot water supply pump 16, and the supplied water is heated by the radiator 12. Then, the hot water heated to a high temperature flows from the water inlet 223 at the top of the hot water storage tank 22. Accordingly, the hot water is sequentially stored from the upper part of the hot water storage tank 22.
When performing bath pursuit, in the primary side water supply circuit of the tank unit 20, the upper high temperature water in the hot water storage tank 22 is discharged from the water supply port 231, and is connected to the external heat exchanger 23, that is, the plate via the pipe 24. It flows into the lower part in the hot water storage tank 22 from the water inlet 222 through the pipe 26 through the heat exchanger 41. As a result, even when the amount of water used for hot water supply is small, the city water is hardly supplied to the bottom of the hot water storage tank 22, and bathing is carried out with a considerable amount of heat accumulated in the hot water storage tank 22, Since the plate-type heat exchanger having a high heat exchange capability can sufficiently perform heat exchange, the lower part of the hot water tank 22 can be kept at a low temperature, and the total amount of heat accumulated in the hot water tank 22 is relatively low. Even if the amount is small, it is possible to heat the bath water at a low temperature (for example, 10 ° C.) to a hot water temperature that can be bathed. In addition, since the heat exchange capability is high, a heat exchanger with a constant capability can be realized in a small size, and space saving can be realized. This circulation operation is performed by the tank hot water use water supply pump 25.
In the secondary side water supply circuit, water from the bathtub 31 is supplied to the plate heat exchanger 41 from the lower water supply port 234 through the pipe 33, and passes through the plate heat exchanger 41 from the upper drainage port 233. Circulating water is sent to the bathtub 31 through the pipe 34. This circulation operation is performed by the water pump 32.

Thus, when the high temperature water of the primary side water supply circuit is supplied from the upper part and the low temperature water of the secondary side water supply circuit is supplied from the lower part, heat is easily transferred upward, so that the upper part of the plate heat exchanger 41 is more The amount of heat exchange can be increased as a high temperature state. Moreover, the lower part of the plate-type heat exchanger 41 can be made into a lower temperature, and the warm water which returns to the hot water storage tank 22 can be made into low temperature.
As described above, the water stored in the lower part of the hot water storage tank 22 is supplied to the radiator 12 of the heat pump circuit 10 to exchange heat.

By reducing the temperature of the water supplied to the radiator 12 of the heat pump circuit 10 as in this embodiment, the heat pump circuit can be operated at a high COP.
In addition, according to the present Example, the water supply pump 32 which supplies the water of the bathtub 31 is arrange | positioned in the upstream of the plate type heat exchanger 41. FIG. Therefore, it is possible to reduce the clogging of the plate heat exchanger 41 with foreign matters such as hair mixed in the water in the bathtub 31.

  The heat pump hot water supply apparatus according to the present invention is useful as a hot water heater with a bath pursuit function for supplying hot water to a bathtub in a general household. It can be used as a water heater with a heating function.

The circuit block diagram in the Example of the heat pump hot-water supply apparatus by this invention (A) is a front view of the plate type heat exchanger in the embodiment of the heat pump hot water supply apparatus according to the present invention, (b) is a side view of the plate type heat exchanger in the embodiment of the heat pump hot water supply apparatus according to the present invention. (A) is a sectional plan view of a tank unit in the embodiment of the heat pump hot water supply apparatus according to the present invention, (b) is a sectional side view of the tank unit in the embodiment of the heat pump hot water supply apparatus according to the present invention. (A) is a front view when the plate type heat exchanger in the embodiment of the heat pump water heater according to the present invention is covered with a heat insulating material, and (b) is a front view when the door is opened from the state of (a). The front view which shows the other Example when the plate type heat exchanger of the heat pump hot-water supply apparatus by this invention is covered with the heat insulating material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Heat pump circuit 11 Compressor 12 Radiator 22 Hot water storage tank 23 External heat exchanger
24, 26 Piping (Primary side water supply circuit)
31 Bathtub 32 Water supply pump 33, 34 Piping (secondary water supply circuit)
41 Plate Heat Exchanger 45 Heat Exchange 46 Heat Insulation 48 Door 49 Window (Opening)

Claims (5)

  A heat pump circuit having a compressor and a radiator, using carbon dioxide as a refrigerant, and operating at a high pressure side exceeding the critical pressure by the compressor, and after heating the water in the lower part of the hot water storage tank with the radiator A hot water storage circuit for returning to the upper part of the hot water storage tank, a primary side water supply circuit for introducing hot water of the hot water storage tank into an external heat exchanger and returning the hot water cooled by the external heat exchanger to the hot water storage tank, A heat pump hot water supply apparatus comprising a secondary side water supply circuit that introduces water into the external heat exchanger and returns hot water heated by the external heat exchanger back into the bathtub, and is a plate as the external heat exchanger A hot water introduced into the external heat exchanger is led out from an upper part of the hot water storage tank using a heat exchanger, and the hot water cooled by the external heat exchanger is introduced from the lower part of the hot water storage tank. Toponpu water heater.   The plate heat exchanger is arranged so that the water supply direction of the primary side water supply circuit flows from the upper part to the lower part, and the water supply direction of the secondary side water supply circuit flows from the lower part to the upper part. The heat pump hot water supply apparatus described in 1.   The heat pump hot water supply apparatus according to claim 1 or 2, wherein a water supply pump is provided in the secondary side water supply circuit, and the water supply pump is disposed on the upstream side of the plate heat exchanger.   The heat pump hot water supply apparatus according to claim 1, 2 or 3, wherein a heat exchanger is provided on a side surface of the hot water storage tank, and the plate heat exchanger is attached to the heat exchanger. A display unit indicating a vertical direction is provided on a surface of the plate heat exchanger, the plate heat exchanger is covered with a heat insulating material, a door or an opening is provided in the heat insulating material, and the door or the opening is provided on the display unit. The heat pump hot water supply apparatus according to any one of claims 1 to 4, wherein the heat pump hot water supply apparatus corresponds to a position.

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