JP5387102B2 - 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. 6, 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.

  Further, 31 is a hot water storage tank, 32 is a circulation pump, and 33 is a three-way valve. A hot water storage circuit that returns from the lower part of the hot water storage tank 31 to the upper part or the lower part of the hot water storage tank 31 through the circulation pump 32, the radiator 2, and the three-way valve 33. 36 is constituted. Further, 34 is a hot water mixing valve, 35 is a boiling temperature sensor, the hot water mixing valve 34 is provided in the mixing portion of the hot water supply pipe from the hot water storage tank 31, and the boiling temperature sensor 35 is provided for the radiator 2. It is equipped so that it may contact from the outer side of piping on water side exit piping.

The operation of the heat pump water heater configured as described above will be described below.
During the boiling operation, the compressor 1 circulates the refrigerant in the heat pump cycle 5, and the circulation pump 32 circulates the water in the hot water storage circuit 36. 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 31 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 is attached to the evaporator 4, the heating operation is switched to the defrosting operation in order to remove the frost. When the defrosting operation is started, the circulation pump 32 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 boiling operation in order 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 31 is selected by the three-way valve 33 depending on the boiling temperature (heating temperature) at the outlet of the radiator 2 and is returned to the hot water storage tank 31. The three-way valve 33 selects a flow path that returns to the lower part of the hot water storage tank 31 while the boiling temperature is lower than the target heating temperature by a certain temperature difference or more. When the boiling temperature is within a certain temperature difference with respect to (temperature), switching is performed so as to select a flow path returning to the upper part of the hot water storage tank 31.

  By operating the three-way valve 33 as described above, the lowering of the hot water temperature due to the reflux of the intermediate hot water to the lower part of the hot water storage tank 31 is suppressed, and heat is stored in the hot water storage tank 31 when the boiling is completed. It acts so that the amount of heat becomes larger (see, for example, Patent Document 1).

  However, when the medium temperature water is returned to the lower part of the hot water storage tank 31, the cold water temperature at the lower part of the hot water storage tank 31 rises, so that the incoming water temperature supplied to the radiator 2 rises, and the energy efficiency during the heating operation by the heat pump cycle 5 is increased. It will decline. In particular, when the defrosting operation is repeatedly performed, the supply water temperature increases greatly.

  Therefore, from the viewpoint of improving the energy efficiency in the boiling operation, it is not a good measure to recirculate a large amount of the medium-temperature water generated as described above to the lower part of the hot water storage tank 31, and the boiling temperature can be quickly increased to the target heating temperature. It is reasonable to reduce the amount of intermediate temperature water returned to the lower part of the hot water storage tank 31.

JP 2002-162108 A

  Since the flow path switching means such as the three-way valve 33 in the conventional heat pump water heater recirculates a large amount of medium-temperature water generated in the return process from the defrosting operation to the lower part of the hot water storage tank 31, every time the defrosting operation is performed, the water enters. The temperature rises, and the energy efficiency during the heating operation by the heat pump cycle 5 is greatly reduced.

  Moreover, the heat pump water heater described in Patent Document 1 delays the circulation pump to a predetermined output, or stops or reduces the output in the process of returning from the defrosting operation. The object of the invention itself is to suppress a decrease in the hot water storage temperature due to a large amount of the intermediate warm water produced being returned to the upper part of the hot water storage tank 11, but the purpose of suppressing the production amount of the intermediate warm water is common, It is also effective for issues.

  However, the amount of medium-temperature water generated differs depending on the target heating temperature. Depending on the target heating temperature, the amount of medium-temperature water generated increases, the incoming water temperature rises, and the energy efficiency during the heating operation by the heat pump cycle 5 is large. There was a problem of a decrease.

  The present invention solves the above-described problem, and a heat pump water heater capable of suppressing a rise in the temperature of water entering the radiator and performing a boiling operation with high energy efficiency in the return process from the defrosting operation. The purpose is to provide.

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 for storing hot fluid heated by the radiator. A tank, a circulation 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, and the radiator and the hot water storage tank. A hot water storage circuit having flow path switching means for switching between a lower flow path communicating with a substantially lower portion, the upper flow path and the lower flow path, and heated by the radiator A temperature sensor for detecting the temperature of the fluid to be heated, and a control unit, and from the defrosting operation for removing frost formation of the evaporator, the circulating pump and the compressor are operated and the radiator Adding the heated fluid After change to the hot water storage operation for the hot water storage to the hot water storage tank, wherein, when the detected temperature of the temperature sensor becomes equal to or higher than a predetermined temperature, the flow path switching means from the state in communication with the lower passage In addition, when switching to communicate with the upper flow path, and after the defrosting operation is completed, and when the flow path switching means is in communication with the lower flow path, the output of the circulation pump is: It is characterized in that it is set so as to be smaller as the target heating temperature of the fluid to be heated set in advance in the radiator is higher. When switching from the defrosting operation to the boiling operation, the target heating is performed. By operating the circulation pump with different output depending on the temperature, it is possible to suppress the amount of intermediate temperature water returning to the substantially lower part of the hot water storage tank in the return process from the defrosting operation. The cold water temperature of substantially lower portion of the tank is kept low, it is possible to obtain an effect that it is possible to perform boiling with high energy efficiency operation.

  ADVANTAGE OF THE INVENTION According to this invention, in the return process from a defrost operation, the raise of the incoming water temperature to a radiator can be suppressed, and the heat pump water heater which can perform a boiling operation with high energy efficiency can be provided.

Configuration diagram of heat pump water heater in Embodiment 1 of the present invention Flow chart for determining the flow path selected by the three-way valve and the output of the circulation pump Correspondence diagram of flow path switching temperature Ta and circulation pump switching temperature Tb with respect to the target heating temperature Tw2. Correspondence diagram of output Pb of circulation pump with respect to the target heating temperature Tw2 Correspondence diagram with flow path switching temperature Ta with respect to target heating temperature Tw2 in Embodiment 2 of the present invention Configuration diagram of conventional heat pump water heater

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 that stores a heated fluid heated by the radiator, and the heated fluid that radiates the heated fluid. A circulation pump that recirculates to the hot water storage tank via a heater, an upper flow path that communicates the radiator and a substantially upper portion of the hot water storage tank, and a lower flow path that communicates the radiator and a substantially lower portion of the hot water storage tank A hot water storage circuit having channel switching means for switching between the channels by selecting either the upper channel or the lower channel, and a temperature sensor for detecting the temperature of the heated fluid heated by the radiator And the control means, and from the defrosting operation for removing the frost formation of the evaporator, the circulating pump and the compressor are operated to heat the heated fluid with the radiator and the hot water storage tank Change to hot water storage operation to store hot water Later, the control means, when the detection temperature of the temperature sensor becomes equal to or higher than a predetermined temperature, the flow path switching means from the state in communication with said lower passage, with switched so as to communicate with the upper channel When the defrosting operation is completed and the flow path switching unit is in communication with the lower flow path, the output of the circulation pump is a preset fluid to be heated in the radiator. as the target heating temperature is high, characterized in that it is set to be smaller, when changing to the hot-water stocking operation from defrosting operation, when the pressure and temperature of the high-pressure side is higher in the steady operating state of the heat pump Operate the circulation pump with a small output, reduce the flow rate of water flowing through the radiator, and quickly reach the pressure and temperature on the high-pressure side to the steady-state pressure and temperature to return from the defrosting operation. Excessive The amount of boiling of the medium-temperature water generated in is reduced, the rise of the chilled water temperature in the lower part of the hot water storage tank due to the reflux is suppressed, and the incoming water temperature is kept low even if the number of defrosting operations is increased, It can be operated with high energy efficiency.

Further, the amount of boiling of the medium temperature water generated in the return process from the defrosting operation is reduced, and the upper flow path is selected while the flow path switching means is operating the circulation pump at a predetermined output. By suppressing the rise of the chilled water temperature at the lower part of the hot water storage tank due to the reflux of the medium temperature water, even if the number of defrosting operations is increased, the incoming water temperature can be kept low and the operation can be performed with high energy efficiency .

The second invention, as the target heating temperature of the preset heated fluid in front Symbol radiator is high, and the target heating temperature, the heat radiation at the time of the channel switching means communicates with the upper channel When the target heating temperature is high, the upper flow path is selected even if the boiling temperature has a large deviation from the target heating temperature. By reducing the amount of boiling of relatively hot medium-temperature water generated during the return process from the defrosting operation and suppressing the rise of the chilled water temperature in the lower part of the hot water storage tank due to the recirculation, the number of defrosting operations Even if the water temperature increases, it is possible to operate with high energy efficiency while keeping the water temperature low.

The third 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 the refrigerant is brought to a supercritical state and heated to a hot water temperature reaching 90 ° C. The medium temperature water generated during operation is returned to the upper part of the hot water storage tank to suppress an increase in the incoming water temperature during the boiling operation, and the boiling operation can be performed with high energy efficiency.

The fourth invention is characterized in that carbon dioxide is used as the refrigerant of the heat pump cycle, and the boiling 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)
First, the configuration of the heat pump water heater in Embodiment 1 of the present invention will be described. In FIG. 1, 13 is a three-way valve which is a flow path switching means, 14 is a circulation pump control means, 15 is a three-way valve control means, and 16 is a boiling temperature sensor.

  Next, the operation and action of the heat pump water heater configured as described above will be described.

  Since the operation and action when the deviation between the boiling temperature and the target heating temperature is within a certain temperature difference are the same as those of the conventional heat pump water heater, a detailed explanation is omitted. Here, the defrosting operation to the boiling operation is omitted. The operation and action when restarting will be described.

During the defrosting operation, the circulation pump 12 is stopped, the expansion valve 3 is fully opened, and a refrigerant at 0 ° C. or higher is supplied to the evaporator 4 to melt and remove the attached frost. When it is determined that the defrosting operation is finished, the expansion valve 3 is throttled to restart the heating pump, and at the same time, the circulation pump 12 also restarts the operation. In the return process from the defrosting operation immediately after resuming the boiling operation, the temperature of the hot water discharged from the radiator 2 is not sufficiently high with respect to the target heating temperature Tw2, and the three-way valve 13 communicates with the lower part of the hot water storage tank 11. A flow path is selected.

  The circulation pump control means 14 operates the circulation pump 12 with a fixed output that is predetermined and smaller than the output in the steady operation state. When the boiling temperature (heating temperature) detected by the boiling temperature sensor 16 becomes higher than a predetermined channel switching temperature of the three-way valve 13, the three-way valve control means 15 switches the three-way valve 13 to change the hot water storage tank 11. When the flow path communicating with the upper part is selected and the boiling temperature detected by the boiling temperature sensor 16 becomes higher than the predetermined circulation pump switching temperature of the three-way valve 13, the circulation pump control means 14 outputs the output of the circulation pump 12. Is switched by feedback control according to the boiling temperature.

  FIG. 2 shows a flowchart of the three-way valve control means 15 for determining the flow path selected by the three-way valve 13 and the output of the circulation pump 12 and the circulation pump control means 14. FIG. 3 shows a correspondence table between the flow path switching temperature Ta and the circulation pump switching temperature Tb with respect to each target heating temperature Tw2, and FIG. 4 shows a correspondence table of the output Pb of the circulation pump 12.

  As shown in FIG. 2, when frost formation on the evaporator 4 is confirmed, the three-way valve 13 is switched to select a flow path communicating with the lower part of the hot water storage tank 11, and the operation of the circulation pump 12 is stopped and removed. The frost operation is started. Then, if it confirms that the frost adhering to an evaporator was removed, a defrost operation will be complete | finished and a heat pump will restart a boiling operation.

  At this time, the circulation pump 12 is operated with a fixed output smaller than the output in the steady operation state. The output at this time corresponds to the target heating temperature Tw2 in the correspondence table of the output Pb of the circulation pump 12 shown in FIG. To be determined. For example, if the target heating temperature is 65 ° C., the circulation pump control means 14 is operated by controlling so that the output of the circulation pump 12 is 20%.

  Thereafter, it is determined whether or not the boiling temperature detected by the boiling temperature sensor 16 has reached the flow path switching temperature Ta shown in FIG. 3 (25 ° C. when the target heating temperature is 65 ° C.). If the temperature has reached the flow path switching temperature Ta, the three-way valve control means 15 switches the three-way valve 13 to a flow path communicating with the upper part of the hot water storage tank 11.

  Further, it is determined whether or not the boiling temperature detected by the boiling temperature sensor 16 has reached the circulating pump replacement temperature Tb (50 ° C. when the target heating temperature is 65 ° C.) shown in FIG. If the temperature has reached the flow path switching temperature Tb, the circulation pump control means 14 determines the output Pb of the circulation pump by feedback control using the boiling temperature detected by the boiling temperature sensor 16 as a controlled variable.

  By controlling and operating the circulation pump 12 and the three-way valve 13 as described above, the amount of medium-temperature water having a low boiling temperature is suppressed, and the three-way valve 13 switches the flow path at an early stage so that the upper portion of the hot water storage tank 11 is The temperature of the cold water in the lower part of the hot water storage tank 11 that has risen every time the defrosting operation is performed can be kept low, and the rise of the incoming water temperature supplied to the radiator 2 can be suppressed.

  By doing in this way, the energy efficiency at the time of the boiling operation by a heat pump can be made high, and power consumption can be reduced.

According to the present embodiment, with the above configuration, when the boiling operation is resumed immediately after the end of the defrosting operation, until the boiling temperature reaches the predetermined circulation pump switching temperature Tb, the predetermined output is used. When the target heating temperature Tw2 is higher, the circulating pump 12 is smaller in operation, and when the boiling temperature reaches a predetermined flow path switching temperature Ta, the hot water tank 11 communicates from the lower part to the upper part. A three-way valve 13 for switching the flow path is provided, the circulation pump switching temperature Tb is set higher than the flow path switching temperature Ta, and the amount of medium-temperature water generated during the return process from the defrosting operation is suppressed, and the lower part of the hot water storage tank 11 By suppressing the amount of medium-temperature water that is recirculated to the water, high energy efficiency can be achieved during the boiling operation.

(Embodiment 2)
Next, the configuration of the heat pump water heater in the second embodiment of the present invention is the same as that in the first embodiment, and the description thereof is omitted. The circulation pump 12 and the three-way valve 13 in this embodiment are controlled and operated by the circulation pump control means 14 and the three-way valve control means 15 according to a flowchart as shown in FIG.

  FIG. 2 shows a flowchart of the three-way valve control means 15 for determining the flow path selected by the three-way valve 13 and the output of the circulation pump 12 and the circulation pump control means 14. FIG. 3 shows a correspondence table between the flow path switching temperature Ta and the circulation pump switching temperature Tb for each target heating temperature Tw2, and FIG. 4 shows a correspondence table for the circulation pump output Pb.

  As shown in FIG. 2, when frost formation on the evaporator 4 is confirmed, the three-way valve 13 is switched to select a flow path communicating with the lower part of the hot water storage tank 11, and the operation of the circulation pump 12 is stopped and removed. The frost operation is started. Then, if it confirms that the frost adhering to an evaporator was removed, a defrost operation will be complete | finished and a heat pump will restart a boiling operation.

  At this time, the circulation pump 12 is operated with a fixed output smaller than the output in the steady operation state. The output at this time corresponds to the target heating temperature Tw2 in the correspondence table of the output Pb of the circulation pump 12 shown in FIG. To be determined.

  For example, if the target heating temperature is 65 ° C., the circulation pump control means 14 operates by controlling the output of the circulation pump 12 to be 20%. Thereafter, whether or not the boiling temperature (heating temperature) detected by the boiling temperature sensor 16 has reached the flow path switching temperature Ta (25 ° C. when the target heating temperature is 65 ° C.) shown in FIG. If the boiling temperature has reached the flow path switching temperature Ta, the three-way valve control means 15 switches the three-way valve 13 to a flow path communicating with the upper part of the hot water storage tank 11.

  Further, it is determined whether or not the boiling temperature detected by the boiling temperature sensor 16 has reached the circulating pump replacement temperature Tb shown in FIG. 3, and if the boiling temperature has reached the flow path switching temperature Tb. The circulating pump control means 14 determines the output Pb of the circulating pump by feedback control using the boiling temperature detected by the boiling temperature sensor 16 as the controlled variable.

  By controlling and operating the circulation pump 12 and the three-way valve 13 as described above, the amount of medium-temperature water having a low boiling temperature is suppressed, and the three-way valve 13 switches the flow path at an early stage so that the upper portion of the hot water storage tank 11 is In particular, during the high-temperature boiling operation (for example, 85 ° C. boiling operation), the cold water temperature at the bottom of the hot water storage tank 11 that has risen every time the defrosting operation is performed is kept low and supplied to the radiator 2. The rise of the incoming water temperature can be suppressed.

  By doing in this way, the energy efficiency at the time of the boiling operation by a heat pump can be made high, and power consumption can be reduced.

  According to the present embodiment, with the above configuration, when resuming the boiling operation immediately after the end of the defrosting operation, the circulation pump 12 is determined in advance until the boiling temperature reaches the predetermined circulation pump switching temperature Tb. The circulating pump 12 is operated with a predetermined output, and the predetermined output becomes smaller as the target heating temperature Tw2 is higher. When the boiling temperature reaches a predetermined flow path switching temperature Ta, the hot water tank 11 communicates from the lower part to the upper part. The three-way valve 13 for switching the flow path is provided, and the higher the target heating temperature Tw2, the larger the deviation between the target heating temperature Tw2 and the flow path switching temperature Ta, and the medium temperature water generated in the return process from the defrosting operation. In particular, by suppressing the amount of intermediate temperature water returned to the lower part of the hot water storage tank 11 during the high temperature boiling operation An effect that can achieve high energy efficiency during heating operation.

  The hot water storage type heat pump water heater of the present invention comprises a circulation pump control means that operates at an output different depending on the target heating temperature at the time of resuming the boiling operation immediately after the end of the defrosting operation, By appropriately suppressing the amount of boiling of medium-temperature water that does not reach the target heating temperature in accordance with the target heating temperature, the temperature of the supply water supplied to the radiator is suppressed from rising every time the defrosting operation is performed. In addition, since it has an effect of enabling the boiling operation with high energy efficiency, it is useful for energy saving of the heat pump water heater.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Expansion valve 4 Evaporator 5 Heat pump cycle 11 Hot water storage tank 12 Circulation pump 13 Three-way valve 15 Three-way valve control means 16 Boiling temperature sensor 17 Hot water storage circuit 21 Heat pump unit 22 Hot water storage unit

Claims (4)

A heat pump cycle in which a compressor, a radiator, a decompressing means, and an evaporator are connected in order; a hot water storage tank for storing hot fluid heated by the radiator; and the hot water storage via the radiator A circulation pump that recirculates to the tank; an upper flow path that communicates the radiator and a substantially upper portion of the hot water storage tank; a lower flow path that communicates the radiator and a substantially lower portion of the hot water storage tank; A hot water storage circuit having flow path switching means for selecting one of the lower flow paths and switching the flow path, a temperature sensor for detecting the temperature of the heated fluid heated by the radiator, and a control means. From the defrosting operation for removing frost formation of the evaporator to the hot water storage operation in which the circulating pump and the compressor are operated to heat the heated fluid with the radiator and store the hot water in the hot water storage tank. after changes to the system Means, said when the temperature detected by the temperature sensor becomes equal to or higher than a predetermined temperature, the flow path switching means from the state in communication with the lower channel, said upper channel and communicating
When the defrosting operation is completed and when the flow path switching means is in communication with the lower flow path, the output of the circulation pump is preset by the radiator. A heat pump water heater, which is set to be smaller as the target heating temperature of the heated fluid is higher. The higher the target heating temperature of the preset fluid to be heated in the radiator, the higher the target heating temperature and the fluid to be heated in the radiator when the channel switching means communicates with the upper channel. The heat pump water heater according to claim 1 , wherein a deviation from the heating temperature is large. The heat pump water heater according to claim 1 or 2 , 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 3 , wherein carbon dioxide is used as a refrigerant of the heat pump cycle.

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