JP5169873B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater that uses hot water boiled using a heat pump.

  Conventionally, this type of heat pump water heater has a structure as shown in FIG.

  In FIG. 5, 1 is a compressor, 2 is a radiator, 3 is an expansion valve, and 4 is an evaporator. These are configured in an annular shape in this order to form a heat pump cycle 5 and arranged in the heat pump unit 21. It is installed. A heat exchanger 7 exchanges heat between the high-pressure refrigerant after passing through the radiator 2 and the low-pressure refrigerant after passing through the evaporator 4 in the heat pump cycle 5.

  Further, 11 is a hot water storage tank, 12 is a circulation pump, and 13 is a three-way valve. The water is recirculated from the lower part of the hot water storage tank 11 to the upper or lower part of the hot water storage tank 11 via the circulation pump 12, the radiator 2 and the three-way valve 13. A circuit 16 is configured. Further, 19 is a hot water supply mixing valve, 15 is a temperature sensor, the hot water supply mixing valve 19 is provided in the mixing portion of the supply water piping and the hot water supply piping from the hot water storage tank 11, and the temperature sensor 15 is the water side outlet piping of the radiator 2. The hot water storage unit 22 is provided on each of them.

  The operation of the heat pump water heater configured as described above will be described below.

  During the hot water storage operation, the compressor 1 circulates the refrigerant in the heat pump cycle 5, and the circulation pump 12 circulates water in the boiling circuit 16. If the heated hot water temperature is sufficiently high, the compressor 1 boils up. The warm water is returned to the upper part of the hot water storage tank 11 and stored.

  In the heat pump cycle 5, the refrigerant is supplied to the radiator 2 after being made high temperature and high pressure in the compressor 1, and after heat is exchanged with water and radiated, the refrigerant is decompressed by the expansion valve 3 to become low temperature and low pressure. Then, it receives heat from the atmosphere and is supplied to the compressor 1 again.

  On the other hand, when the outside air temperature is low and frost adheres to the evaporator 4, the hot water storage operation is switched to the defrost operation in order to remove the frost. When the defrosting operation is started, the circulation pump 12 is stopped, the amount of pressure reduction in the expansion valve 3 is reduced, and a refrigerant of 0 ° C. or higher is supplied to the evaporator 4 to melt and remove the attached frost. .

  When the adhering frost has been sufficiently removed, the operation is switched from the defrosting operation to the hot water storage operation to boil the hot water again. At this time, the flow path communicating with either the upper part or the lower part of the hot water storage tank 11 is selected by the three-way valve 13 depending on the boiling temperature at the outlet of the radiator 2 and is returned to the hot water storage tank 11. The three-way valve 13 selects a flow path that returns to the lower part of the hot water storage tank 11 while generating warm water having a boiling temperature that is lower than a certain temperature difference with respect to the target boiling temperature. When the boiling temperature falls within a certain temperature difference, switching is performed so as to select a flow path that returns to the upper part of the hot water storage tank 11.

  By operating the three-way valve 13 as described above, the lowering of the hot water temperature in the upper part due to the reflux of the intermediate hot water to the lower part of the hot water storage tank 11 is suppressed, and heat is stored in the hot water storage tank 11 when the boiling is completed. It works to increase the amount of heat.

  However, when the intermediate temperature water is returned to the lower part of the hot water storage tank 11, the cold water temperature at the lower part of the hot water storage tank 11 rises, so that the incoming water temperature supplied to the radiator 2 rises and the energy efficiency during the hot water storage operation by the heat pump cycle 5 decreases. Resulting in. In particular, when the defrosting operation is repeatedly performed, the incoming water temperature greatly increases.

Therefore, from the viewpoint of improving the energy efficiency in the hot water storage operation, it is not a good idea to recirculate the medium-temperature water generated as described above to the lower part of the hot-water storage tank 11, but only when heat storage with high-temperature hot water is necessary. It is reasonable to return the medium-temperature water to be returned to the lower part of the hot water storage tank 11.
JP 2003-279136 A

  The flow path switching means such as the three-way valve 13 in the conventional heat pump water heater returns to the lower part of the hot water storage tank 11 the intermediate hot water generated when the hot water storage operation is resumed immediately after the defrosting operation is completed, regardless of the necessity of heat storage with hot hot water. Therefore, every time the defrosting operation is performed, the incoming water temperature rises, and the energy efficiency during the hot water storage operation by the heat pump cycle 5 is lowered.

  In the heat pump water heater described in Patent Document 1, when the boiling temperature is equal to or higher than a certain temperature difference with respect to the target boiling temperature, the generated medium-temperature water is supplied again to the radiator via the bypass circuit. Therefore, there is no problem as described above. However, there is a problem that the energy efficiency when boiling the warm water once supplied to the radiator again through the bypass circuit is extremely low, and the amount of power consumed for the hot water storage operation is increased.

  This invention solves said subject, and it aims at providing the heat pump water heater which can suppress the raise of incoming water temperature and can perform hot water storage operation with high energy efficiency.

In order to achieve the above object, a heat pump water heater of the present invention includes a heat pump cycle in which a compressor, a radiator, a decompression means, and an evaporator are connected in order, and a hot water storage tank for storing hot fluid heated by the radiator. A circulating pump that recirculates the heated fluid to the hot water storage tank via the radiator, an upper flow path that communicates the radiator and a substantially upper portion of the hot water storage tank, a substantially lower portion of the radiator and the hot water storage tank, A hot water storage circuit having flow path switching means for switching the flow path by selecting either the upper flow path or the lower flow path, and the heated fluid after passing through the radiator A temperature detecting means for detecting the temperature, and a control means, in order to remove the frost formation of the evaporator, from the defrosting operation in which the circulation pump is stopped and the compressor is operated, the circulation pump, the compression Luck It is allowed Oite when the change to the hot water storage operation for the hot water storage to the hot water storage tank to heat the heated fluid at the radiator, when the temperature difference between the detected temperature of the target boiling temperature to the temperature sensing means is within a predetermined value The control means performs switching so that the flow path switching means selects the upper flow path, and the predetermined value is smaller in the midnight time zone than in the daytime time zone .

Thus, by controlling the operation of the flow path switching means by a control method that differs depending on the time zone, in the time zone where there is no need for heat storage with high-temperature hot water, By switching the switching means so as to communicate with the upper flow path communicating with the substantially upper part of the hot water storage tank and returning the warm water to the upper side of the hot water storage tank, it is possible to suppress an increase in the incoming water temperature .

  Therefore, a heat pump water heater capable of performing hot water storage operation with high energy efficiency can be provided.

In addition, during the midnight hours, the medium temperature water generated when the hot water storage operation is resumed immediately after the end of the defrosting operation is returned to the lower part of the hot water storage tank to increase the amount of heat stored in the hot water storage tank when the midnight boiling is completed. In the time zone, hot water storage operation is performed with high energy efficiency by suppressing the rise of the incoming water temperature during hot water storage operation by returning the medium temperature water generated when resuming the hot water storage operation immediately after the defrost operation is completed to the upper part of the hot water storage tank. Can do.

  According to the present invention, it is possible to provide a heat pump water heater that stores a large amount of heat in a hot water storage tank in a necessary time zone and performs hot water storage operation with high energy efficiency.

A first invention includes a heat pump cycle in which a compressor, a radiator, a decompression unit, and an evaporator are connected in order, a hot water storage tank for storing a heated fluid heated by the radiator, and the heated fluid as the radiator. A circulation pump that recirculates to the hot water storage tank via the upper passage, an upper flow passage that communicates the radiator and a substantially upper portion of the hot water storage tank, a lower flow passage that communicates the radiator and a substantially lower portion of the hot water storage tank, A hot water storage circuit having a flow path switching means for switching between the flow paths by selecting either the upper flow path or the lower flow path, a temperature detection means for detecting the temperature of the heated fluid after passing through the radiator, Control means, and in order to remove frost formation of the evaporator, from the defrosting operation in which the circulation pump is stopped and the compressor is operated, the circulation pump and the compressor are operated, and the radiator Heat the heated fluid The Oite when changing to a hot water storage operation for the hot water storage to the hot water storage tank, the temperature difference between the detected temperature of the target boiling temperature to the temperature sensing means is within a predetermined value, said control means, said flow path switching unit is the In addition to switching to select the upper flow path, the predetermined value is smaller in the midnight time zone than in the daytime time zone .

Thus, by controlling the operation of the flow path switching means by a control method that differs depending on the time zone, in the time zone where there is no need for heat storage with high-temperature hot water, By switching the switching means so as to communicate with the upper flow path communicating with the substantially upper part of the hot water storage tank and returning the warm water to the upper side of the hot water storage tank, it is possible to suppress an increase in the incoming water temperature .

Therefore, a heat pump water heater capable of performing hot water storage operation with high energy efficiency can be provided .

In addition, during the midnight hours, the medium temperature water generated when the hot water storage operation is resumed immediately after the end of the defrosting operation is returned to the lower part of the hot water storage tank to increase the amount of heat stored in the hot water storage tank when the midnight boiling is completed. In the time zone, hot water storage operation is performed with high energy efficiency by suppressing the rise of the incoming water temperature during hot water storage operation by returning the medium temperature water generated when resuming the hot water storage operation immediately after the defrost operation is completed to the upper part of the hot water storage tank. Can do.

The second invention is characterized in that during hot water storage operation, the high pressure side of the heat pump cycle is operated at supercritical pressure, and hot water can be stored.

The third invention is characterized in that carbon dioxide is used as the refrigerant of the heat pump cycle, and the hot water storage operation can be performed with high energy efficiency without risk of ignition or explosion of the refrigerant.

  Hereinafter, a heat pump water heater in an embodiment of the present invention will be described with reference to the drawings.

  Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat pump water heater in the first embodiment of the present invention. In FIG. 1, 13 is a three-way valve, 14 is a three-way valve control means, and 15 is a temperature sensor for detecting the boiling temperature.

  Hereinafter, the operation and action of the heat pump water heater will be described.

  Since the operation and action when the deviation between the boiling temperature and the target boiling temperature is within a certain temperature difference are the same as those of a conventional heat pump water heater, a detailed description thereof will be omitted. The operation and action when resuming operation will be described.

  During the defrosting operation, the circulation pump 12 is stopped, the opening degree of the expansion valve 3 is maximized, and the high-temperature compressed refrigerant is supplied from the compressor 1 to the evaporator 4 to melt and remove the attached frost. . When the end of the defrosting operation is determined, the operation of the circulation pump 12 is started, and the expansion valve 3 is throttled to restart the hot water storage operation. Immediately after resuming the hot water storage operation, the temperature of the hot water exiting the radiator 2 is lower than the target boiling temperature, so the three-way valve 13 selects the flow path 18 communicating with the lower part of the hot water storage tank 11. When the detected temperature becomes higher than a predetermined temperature, the three-way valve control means 14 switches the three-way valve 13 and selects the flow path 17 communicating with the upper part of the hot water storage tank 11.

  A flowchart of the three-way valve control means 14 for determining the flow path selected by the three-way valve 13 is shown in FIG. As shown in FIG. 2, when the start of the defrosting operation is determined, the three-way valve 13 is switched to select the flow path 18 communicating with the lower part of the hot water storage tank 11, and the current time is the daytime time zone (7:00 am -11pm) or midnight time zone (11:00 am to 7:00 am).

If the current time is in the daytime period, when the hot water storage operation is resumed immediately after the defrosting operation is finished, the temperature of the hot water that is the boiling temperature after passing through the radiator 2 detected by the temperature sensor 15 and the target boiling temperature are calculated. It is determined whether the difference is 45 ° C. or less (for example, if the target boiling temperature is 70 ° C., the boiling temperature is 25 ° C. or more). If the temperature difference is 45 ° C., the three-way valve control means 14 The three-way valve 13 is switched to the flow path 17 communicating with the upper part of the hot water storage tank 11.

  On the other hand, if the current time is midnight, the difference between the temperature detected by the temperature sensor 15 and the target boiling temperature is 15 ° C. or less (for example, if the target boiling temperature is 70 ° C., the boiling temperature 55 When the temperature becomes equal to or higher than [° C.], the three-way valve control means 14 switches the three-way valve 13 to the flow path 17 communicating with the upper part of the hot water storage tank 11.

  As described above, by controlling the three-way valve 13 to operate, during the daytime period, the medium temperature water whose temperature difference is within 45 ° C with respect to the target boiling temperature is relatively low, By recirculating to the upper part of the heat pump cycle 5, the cold water temperature at the lower part of the hot water storage tank 11 that has been raised every time the defrosting operation is performed is kept low, and the rise of the incoming water temperature supplied to the radiator 2 is suppressed. Can improve the energy efficiency during hot water storage operation.

  On the other hand, in the midnight time zone, the hot water having a relatively high temperature whose boiling temperature is within a temperature difference of 15 ° C. with respect to the target boiling temperature is also returned to the lower part of the hot water tank 11, so that the hot water storage tank The temperature drop of the hot water of 11 upper part is suppressed, and the calorie | heat amount stored in the hot water storage tank 11 at the time of completion of midnight boiling can be enlarged.

  By doing so, a large amount of heat can be stored in the hot water storage tank 11 in a necessary time zone, and the energy efficiency during hot water storage operation can be increased, and the amount of power consumption can be reduced.

  According to the present embodiment, with the above-described configuration, when the boiling temperature reaches a predetermined temperature in the daytime time zone and midnight time zone when the hot water storage operation is resumed immediately after the defrosting operation is finished, the lower part of the hot water storage tank 11 The flow path is switched so as to communicate with the upper part from the top.

  Then, by setting the flow path switching temperature in the midnight hours higher than the flow path switching temperature in the daytime hours, during the daytime hours, the medium-temperature water generated at the start of the hot water storage operation or after the defrosting operation is stored. By returning to the upper part of the tank 11 and returning the intermediate temperature water to the lower part of the hot water storage tank 11 in the midnight time zone, it is possible to realize high energy efficiency during hot water storage operation while storing a large amount of heat in the required time zone. There is an effect.

( Reference Example 1 )
Next, the configuration of the heat pump water heater in Reference Example 1 of the present invention is the same as the configuration in the first embodiment. The three-way valve 13 in this reference example is controlled and operated by the three-way valve control means 14 according to different control methods in the daytime time zone and the midnight time zone according to the flowchart as shown in FIG.

  In the daytime period, when the hot water storage operation is resumed immediately after the end of the defrosting operation, the circulation pump 12 is started to circulate water through the boiling circuit 16, and at the same time, the three-way valve 13 is controlled by the three-way valve control means 14. It is switched to the flow path communicating with the upper part. On the other hand, in the midnight time zone, when the temperature detected by the temperature sensor 15 falls within 15 ° C. with respect to the target boiling temperature when the hot water storage operation is resumed immediately after the defrosting operation is finished, the three-way valve control means 14 The three-way valve 13 is switched to a flow path communicating with the upper part of the hot water storage tank 11.

By operating the three-way valve 13 as described above, during the daytime period, the circulation pump 12 is started, and the medium-temperature water generated when the hot water storage operation is resumed immediately after the defrosting operation is returned to the upper part of the hot water storage tank 11 to be removed. The rise of the cold water temperature at the lower part of the hot water storage tank 11 is suppressed every time the frost operation is performed, and the rise of the incoming water temperature supplied to the radiator 2 is suppressed, thereby improving the energy efficiency during the hot water storage operation by the heat pump cycle 5. On the other hand, in the midnight time zone, when the hot water storage operation is resumed immediately after the end of the defrosting operation, the medium hot water whose boiling temperature is more than 15 ° C. with respect to the target boiling temperature is recirculated to the lower part of the hot water storage tank 11. The temperature drop of the hot water in the upper part of the tank 11 is suppressed, and the amount of heat stored in the hot water storage tank 11 at the completion of midnight boiling can be increased.

  By doing so, a large amount of heat can be stored in the hot water storage tank 11 in a required time zone, and the energy efficiency during hot water storage operation can be increased, thereby reducing the amount of power consumption.

According to this reference example , with the above configuration, in the daytime period, when the hot water storage operation is resumed immediately after the defrosting operation is completed, the flow path is switched so as to communicate from the lower part of the hot water storage tank 11 to the upper part when the circulation pump is started. When the hot water storage operation resumes immediately after the end of the defrosting operation, the three-way valve 13 that switches the flow path is provided in the midnight time zone, and the defrosting operation ends in the daytime time zone. The intermediate warm water generated when the hot water storage operation is resumed immediately after is returned to the upper part of the hot water storage tank 11, and the intermediate warm water is returned to the lower part of the hot water storage tank 11 in the late-night time period, thereby storing a large amount of heat in the necessary time zone. It has the effect of realizing high energy efficiency during hot water storage operation.

( Reference Example 2 )
Next, the configuration of the heat pump water heater in Reference Example 2 of the present invention is the same as the configuration in the first embodiment. The three-way valve 13 in this reference example is controlled and operated by the three-way valve control means 14 according to different control methods in the daytime time zone and the midnight time zone according to the flowchart as shown in FIG.

  In the daytime period, when the hot water storage operation is resumed immediately after the defrosting operation is started, the air blowing means 6 that guides air to the evaporator starts, and at the same time, the three-way valve control means 14 causes the three-way valve 13 to communicate with the upper part of the hot water storage tank 11. Switch to the road. On the other hand, in the midnight time zone, when the temperature detected by the temperature sensor 15 falls within 15 ° C. with respect to the target boiling temperature when the hot water storage operation is resumed immediately after the defrosting operation is finished, the three-way valve control means 14 The three-way valve 13 is switched to a flow path communicating with the upper part of the hot water storage tank 11.

  By operating the three-way valve 13 as described above, in the daytime time period, the blowing means 6 is started, and the medium-temperature water generated when the hot water storage operation is resumed immediately after the defrosting operation is ended is returned to the upper part of the hot water storage tank 11. Moreover, the rise in the cold water temperature at the bottom of the hot water storage tank 11 is suppressed, the rise in the incoming water temperature supplied to the radiator 2 is suppressed, and the energy efficiency during the hot water storage operation by the heat pump cycle 5 is improved. On the other hand, in the midnight time zone, when the hot water storage operation is resumed immediately after the end of the defrosting operation, the medium hot water whose boiling temperature is more than 15 ° C. with respect to the target boiling temperature is recirculated to the lower part of the hot water storage tank 11. The temperature drop of the hot water in the upper part of the tank 11 is suppressed, and the amount of heat stored in the hot water storage tank 11 at the completion of midnight boiling can be increased.

  As a result, a large amount of heat can be stored in the hot water storage tank 11 in the required time zone, and the energy efficiency during hot water storage operation can be increased, thereby reducing the amount of power consumption.

According to this reference example , with the above-described configuration, in the daytime period, when the hot water storage operation is resumed immediately after the defrosting operation is completed, the flow path is communicated from the lower part of the hot water storage tank 11 to the upper part when the blower unit 6 is started. When the hot water storage operation is resumed immediately after the end of the defrosting operation, the three-way valve 13 for switching the flow path is provided in the switching and midnight time zone, and the defrosting operation is performed in the daytime time zone. The intermediate temperature water generated at the time of resuming the hot water storage operation immediately after completion is returned to the upper part of the hot water storage tank 11, and the intermediate temperature water is returned to the lower part of the hot water storage tank 11 in the midnight time period, thereby storing a large amount of heat in a necessary time zone. This also has the effect of realizing high energy efficiency during hot water storage operation.

  The hot water storage type heat pump water heater of the present invention makes it possible to perform hot water storage operation with high energy efficiency when hot water storage operation is resumed immediately after the completion of the defrosting operation, and to generate a large amount of heat in the hot water storage tank in the required time zone. Since it has the effect of making it possible to store heat, it is useful for energy saving of the heat pump water heater and prevention of running out of hot water.

Configuration diagram of heat pump water heater in Embodiment 1 of the present invention The flowchart which determines the flow path which the three-way valve in Embodiment 1 of this invention selects The flowchart which determines the flow path which the three-way valve in the reference example 1 of this invention selects. The flowchart which determines the flow path which the three-way valve in the reference example 2 of this invention selects Configuration diagram of conventional heat pump water heater

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Expansion valve 4 Evaporator 5 Heat pump cycle 6 Blowing means 11 Hot water storage tank 12 Circulation pump 13 Three-way valve 14 Three-way valve control means 15 Temperature sensor 16 Boiling circuit

Claims (3)

A heat pump cycle in which a compressor, a radiator, a decompression unit, and an evaporator are connected in order; a hot water storage tank for storing a heated fluid heated by the radiator; and the hot water storage tank for storing the heated fluid via the radiator A circulation pump that recirculates to the heat source, an upper flow path that communicates the radiator and a substantially upper part of the hot water storage tank, a lower flow path that communicates the radiator and a substantially lower part of the hot water storage tank, the upper flow path and the lower flow path A hot water storage circuit having a flow path switching means for selecting one of the side flow paths and switching the flow path, a temperature detection means for detecting the temperature of the heated fluid after passing through the radiator, and a control means , In order to remove frost from the evaporator, the circulating pump and the compressor are operated from the defrosting operation in which the circulating pump is stopped and the compressor is operated, and the heated fluid is heated by the radiator. The hot water storage tongue Oite when changing to a hot water storage operation for the hot water storage to the temperature difference between the target water heating temperature and the detected temperature of said temperature detecting means is within a predetermined value, said control means, said flow path switching unit is the upper channel The heat pump water heater is characterized in that the predetermined value is smaller in the midnight time zone than in the daytime time zone . The heat pump water heater according to claim 1 , wherein the high pressure side of the heat pump cycle is operated at a supercritical pressure during hot water storage operation. The heat pump water heater according to claim 2 , wherein carbon dioxide is used as a refrigerant of the heat pump cycle.

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