JP5776314B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater, and more particularly to a technique that can be suitably applied to a heat pump water heater using a hydrocarbon (HC) refrigerant such as propane as a refrigerant.

Conventionally, a compressor, a hot water supply heat exchanger, a decompression means, and a heat source heat exchanger are connected in order by a refrigerant circulation pipe, and water supplied to the hot water supply heat exchanger by a water supply pump is supplied by the compressor. 2. Description of the Related Art There is known a heat pump water heater provided with a hot water supply circuit that is used for hot water supply by heat exchange heating with a compressed high-pressure refrigerant. In such a heat pump water heater, it has been proposed to control the operation of the compressor, the pressure reducing means, and the water supply pump so that the discharge temperature of the high-pressure refrigerant that is compressed and discharged by the compressor becomes a predetermined target temperature. (For example, see Patent Documents 1 to 3). In each of these heat pump water heaters, carbon dioxide (CO ₂ ) is used as a refrigerant, and heat exchange heating is performed using the refrigerant in a supercritical state by compressing the carbon dioxide (CO ₂ ) above the critical pressure with a compressor. .

Japanese Patent No. 3601369 Japanese Patent No. 3843963 JP 2004-361046 A

The inventors of the present invention use hydrocarbon (HC) refrigerants such as propane, which are known as a kind of refrigerant, but have various difficulties and have not been used as refrigerants in the past. We have been developing a heat pump water heater. Such an HC refrigerant can be used with a compressor having a lower compression capacity than a CO ₂ refrigerant, but condenses due to heat exchange in the hot water heat exchanger, resulting in a phase change. Management has problems that it is difficult to control the temperature of the hot water and that it is difficult to achieve good energy consumption efficiency. That is, the heat exchange in the hot water supply heat exchanger is heat exchange with sensible heat that does not cause a phase change in the case of a CO2 refrigerant. In the case of a system refrigerant, heat exchange is performed with latent heat that changes to a gas / liquid phase, so that it is difficult to manage the tapping temperature. In order to cope with this, it is conceivable to manage the condensing temperature in the heat exchanger for hot water supply instead of the discharge temperature from the compressor as in the case of the CO2 refrigerant. This is accompanied by unnecessary energy consumption, which hinders optimization of energy consumption efficiency.

  This invention is made | formed in view of such a situation, The place made into the objective is providing the heat pump water heater which can aim at the optimization of energy consumption efficiency, controlling a tapping temperature accurately. is there.

In order to achieve the above object, in the present invention , the compressor, the hot water supply heat exchanger, the pressure reducing means, and the heat source heat exchanger are sequentially connected by the refrigerant circulation pipe, and the water supply pump The heat pump water heater provided with a hot water supply circuit that heats and heats the water that has entered the heat exchanger for hot water supply with the refrigerant discharged from the compressor to be discharged is provided with the following specific items. . Sunawa Chi, with HC-based refrigerant as the refrigerant circulated in the refrigerant circuit, and the discharge temperature detection means for detecting the discharge temperature of the refrigerant discharged from the pre-Symbol compressor, outside air temperature detection means for detecting an outside air temperature And an incoming water temperature detecting means for detecting an incoming water temperature entering the hot water supply heat exchanger, and a hot water temperature for detecting the temperature of hot water that is heated by heat exchange and passed through the hot water heat exchanger. a temperature difference between the detecting means, and discharge temperature of the refrigerant discharged from the pre-Symbol compressor, a hot water temperature of the hot water to be tapped from the hot water supply heat exchanger is detected by the outside temperature detecting means Suppose that it comprises target temperature difference determination processing means for determining a target temperature difference corresponding to the detected outside air temperature, the detected incoming water temperature detected by the incoming water temperature detecting means, and the set hot water temperature. In addition, the tapping so that the detected hot water temperature detected by the temperature detecting means becomes the set hot water temperature, a first control means for changing control of the operation control amount before Symbol compressor, detected by the discharge temperature detecting means A second control unit that changes and controls the operation control amount of the decompression unit so that the temperature difference between the detected discharge temperature and the detected tapping temperature becomes the target temperature difference determined by the target temperature difference determination processing unit. Control means . Then, the control control amount of the compressor is changed and controlled by the first control means, and then the operation of the compressor is kept constant with the operation control amount controlled by the change control. The operation control amount of the pressure reducing means is changed and controlled (Claim 1 ).

In the case of the present invention, even if a refrigeration cycle in which the refrigerant is condensed by the heat exchange with water in the heat exchanger for hot water supply to cause a phase change by the change control by the first control means is executed in the refrigerant circulation circuit, It becomes possible to control the temperature so that the hot water that has undergone heat exchange heating in the hot water supply heat exchanger becomes the set hot water temperature. In addition, when the refrigeration cycle using the heat in the latent heat region for heat exchange as described above is executed in the refrigerant circulation circuit by the change control based on the target temperature difference by the second control means. Even in this case, the optimization can be achieved from the viewpoint of energy consumption without wasting energy associated with the operation of the compressor. In particular, even if an HC refrigerant that is condensed and phase-changed by heat exchange with water in a hot water supply heat exchanger is used as a refrigerant in a heat pump water heater, energy is controlled with high accuracy as described above. It is also possible to optimize consumption efficiency. Further, the condensation temperature detecting means detects the condensation temperature of the refrigerant condensed by heat exchange in the hot water supply heat exchanger, and compresses the detected condensation temperature to a target condensation temperature determined based on the set hot water temperature. Compared with the case where the first control means is configured to change and control the operation control amount of the machine , the condensation temperature detecting means can be omitted, and the number of parts and cost can be reduced.

As the target temperature difference determination processing means in the present invention described above, the temperature difference at which the energy consumption efficiency on the refrigerant circuit side is maximized (coefficient of performance: COP is maximized) with respect to the operation amount of the compressor. (Claim 2 ). By doing in this way, it becomes possible to perform the driving | operation which optimized the energy consumption efficiency reliably by the change control by the said 2nd control means.

As described above, according to the heat pump water heater of the present invention , the refrigeration in which the refrigerant condenses due to heat exchange with water in the hot water heat exchanger due to the change control by the first control means. Even if the cycle is executed in the refrigerant circulation circuit, the temperature can be controlled so that the hot water that has undergone heat exchange heating in the hot water supply heat exchanger becomes the set hot water temperature. In addition, when the refrigeration cycle using the heat in the latent heat region for heat exchange as described above is executed in the refrigerant circulation circuit by the change control based on the target temperature difference by the second control means. Even in this case, optimization can be achieved from the viewpoint of energy consumption without wasting energy associated with the operation of the compressor. In particular, even if the HC-based refrigerant will change phase and condensed by heat exchange with the water in the hot water supply heat exchanger is adopted as the refrigerant of the heat pump water heater, the accuracy with good hot water temperature control as, It is possible to optimize energy consumption efficiency. Further, the condensation temperature detecting means detects the condensation temperature of the refrigerant condensed by heat exchange in the hot water supply heat exchanger, and compresses the detected condensation temperature to a target condensation temperature determined based on the set hot water temperature. Compared to the case where the first control means is configured to change and control the operation control amount of the machine , the condensation temperature detection means can be omitted, and the number of parts and cost can be reduced.

In particular, according to claim 2 , by determining the value of the temperature difference at which the output heat amount on the refrigerant circulation circuit side becomes the maximum with respect to the operating amount of the compressor as the target temperature difference, by the change control by the second control means As a result, it is possible to reliably perform an operation that optimizes the energy consumption efficiency.

It is a mimetic diagram of a heat pump hot-water supply machine concerning an embodiment of the present invention. It is a control block diagram of the reference form using the heat pump water heater of FIG. Tests for changes in discharge temperature, tapping temperature, and condensation temperature when the expansion valve opening is changed with the compressor operating at a constant speed under a certain combination of outside air temperature, incoming water temperature, and set hot water temperature It is a relationship figure which shows an example of the result obtained. Output heat quantity and COP at that time when the opening of the expansion valve is changed with the operating speed of the compressor kept constant under the same combination of outside air temperature, incoming water temperature and set hot water temperature as in FIG. It is a related figure which shows an example of the result of having tested and calculated about the change of (score of performance). It is a control flowchart concerning the hot water temperature control of FIG. It is a control block diagram of the implementation form using a heat pump water heater of FIG. It is a 3 equivalent diagram for explaining a table used in the implementation form. 7 is a control flowchart according to the tapping temperature control of FIG. 6. It is a related figure which shows an example of the result of having tested about the change of the discharge temperature and the condensation temperature at the time of changing the incoming flow rate with respect to the heat exchanger for hot water supply.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a heat pump water heater according to an embodiment of the present invention. This heat pump water heater is a combination of a refrigerant circulation circuit 1 and a hot water supply circuit 2 using an HC refrigerant (for example, propane; hereinafter simply referred to as “refrigerant”). The water can be heat exchange heated. In the refrigerant circulation circuit 1, a compressor 11, a hot water supply heat exchanger (condenser) 12, an expansion valve 13 as a pressure reducing means, and a heat source heat exchanger (evaporator) 14 are connected in order through a refrigerant circulation pipe 15. It is a thing. The hot water supply circuit 2 is also provided with a hot water storage tank 21, a water circulation pipe 22 for circulating hot water stored in the hot water storage tank 21 between the hot water supply heat exchanger and water from the bottom of the hot water storage tank 21. A water supply pump 23 is provided which is pumped to the heat exchanger 12 and led from the hot water supply heat exchanger 12 to the top of the hot water storage tank 21 after heating. Then, the refrigerant circulation circuit 1 and the hot water supply circuit 2 are operated and controlled by the controller 3, and in the hot water supply heat exchanger 12, water is heated to a set hot water temperature input and set to a remote controller (not shown), and a hot water storage tank 21. Hot water is stored in the room.

  The compressor 11 is operated by an electric motor, and the operation of the compressor 11 is controlled by the controller 3 with the rotation speed as an operation control amount. The rotational speed is controlled by changing the operating frequency given from the controller 3. In order to compress to a higher pressure, the rotational speed is increased, and to lower the pressure, the rotational speed is decreased. By being compressed by the compressor 11, the refrigerant in a high-temperature gas phase state is discharged from the compressor 11 to the refrigerant circulation pipe 15, the discharge temperature is detected by the discharge temperature sensor 16, and the detected discharge temperature is output to the controller 3. Will be. Here, since the HC refrigerant is used in the present embodiment, the compressor 11 can be configured with a compressor having a significantly lower compression capacity than when the CO2 refrigerant is used.

  In the hot water supply heat exchanger 12, a part of the refrigerant circulation pipe 15 is passed through the inside, while a part of the water circulation pipe 22 is passed through the inside from the reverse direction to exchange heat therebetween. . That is, the high-temperature gas-phase refrigerant discharged from the compressor 11 to the refrigerant circulation pipe 15 and the water supplied from the bottom of the hot water storage tank 21 by the water supply pump 23 are subjected to heat exchange, and the water becomes hot water by heat exchange heating. The refrigerant that has been deprived of heat by the heat exchange condenses and changes into a liquid phase. The condensation temperature at the time of this phase change is detected by the condensation temperature sensor 17, and this detected condensation temperature is output to the controller 3. The detection of the condensation temperature by the condensation temperature sensor 17 is to detect the temperature of the refrigerant at an intermediate position in the heat exchange process in the hot water supply heat exchanger 12.

  The expansion valve 13 depressurizes the refrigerant that has been in the liquid phase in the hot water supply heat exchanger 12. The operation of the expansion valve 13 is controlled by the controller 3 using the opening degree as an operation control amount.

  The heat source heat exchanger 14 includes a fan 14a that blows outside air by its rotational operation, and heat exchange is performed between the outside air and the refrigerant decompressed by the expansion valve 13, thereby evaporating the refrigerant to a gas phase state. It is supposed to convert. The refrigerant in the gas phase is compressed again in the compressor 11 and becomes a high temperature gas phase.

  On the other hand, in the hot water supply circuit 2, when the water in the hot water storage tank 21 is pumped to the hot water supply heat exchanger 12 by the operation of the water supply pump 23, heat exchange is performed by the incoming water temperature sensor 24 in front of the inlet of the hot water supply heat exchanger 12. The incoming water temperature before heating is detected, and this detected incoming water temperature is output to the controller 3. Further, when the hot water is heated by heat exchange by passing through the hot water supply heat exchanger 12, the hot water temperature is detected by the hot water temperature sensor 25 on the outlet side of the hot water heat exchanger 12, and the detected hot water temperature is determined by the controller. 3 is output. In addition, the outside air temperature is detected by the outside air temperature sensor 26 and output to the controller 3. The hot water heated by the hot water supply heat exchanger 12 is returned to the top side of the hot water storage tank 21 and stored, and used for subsequent hot water supply. If the amount of hot water in the hot water storage tank 21 is reduced by hot water supply, water is supplied accordingly.

  The above-described operation control of the heat pump water heater is executed by the controller 3 having an MPU, a memory, and the like. The controller 3 has a set hot water temperature as a target temperature and a hot water supply heat exchanger 12 for controlling the hot water supply circuit 2 to heat the water on the hot water supply circuit 2 side to the set hot water temperature, and a target temperature difference used for the control. A target temperature difference determination processing means 32 for determining, and a storage means 33 in which a target value table 331, an FF value (feedforward control value) table 332 and the like used for determining the target temperature difference and the like are stored and set in advance. Yes.

The hot water temperature control means 31 in the reference form includes a compressor control unit 311 as a first control means and an expansion valve control unit 312 as a second control means. The compressor control unit 311 changes and controls the rotational speed of the compressor 11 so that the detected condensing temperature becomes a target condensing temperature determined based on the set hot water supply temperature, while the expansion valve control unit 312 controls the rotational speed of the compressor 11. The opening degree of the expansion valve 13 is changed and controlled so that the temperature difference between the detected discharge temperature and the detected condensing temperature becomes the target temperature difference determined by the target temperature difference determination processing means 32 in a state where the pressure is kept constant. ing.

  The target temperature difference determination processing means 32 discharges from the compressor 11 in a combination of the detected outside air temperature from the outside air temperature sensor 26 at the time of the current operation, the detected incoming water temperature from the incoming water temperature sensor 24, and the set hot water temperature. The temperature difference between the temperature and the condensing temperature in the hot water supply heat exchanger 12 and the temperature difference at which the energy consumption efficiency is maximized (coefficient of performance: COP is maximized) is determined as the target temperature difference. Yes. In this determination process, the target temperature difference is determined from the target value table 331 based on the combination of the detected outside air temperature, the detected incoming water temperature, and the set hot water temperature. In the target value table 331, a value of a temperature difference between the discharge temperature and the condensing temperature at which the COP is maximized under various combinations of the outside air temperature, the incoming water temperature, and the set hot water temperature is obtained in advance by testing and calculation. It has been established.

  The target temperature difference value in the target value table 331 may be obtained as follows. FIG. 3 shows a case where the opening degree of the expansion valve 13 is changed in a state where the rotation speed of the compressor 11 is kept constant under certain specific outside air temperature, incoming water temperature and set hot water temperature (for example, 65 ° C.). In addition, how the discharge temperature, the tapping temperature and the condensing temperature change is determined by a test. FIG. 4 shows a case where the opening degree of the expansion valve 13 is changed with the rotation speed of the compressor 11 kept constant under the same conditions of the outside air temperature, the incoming water temperature and the set hot water temperature as in FIG. In addition, how the output heat quantity changes is obtained in the test, and the COP at that time is obtained by calculation. Here, looking at FIG. 4, the output heat amount becomes maximum and the COP also shows the maximum value when the expansion valve opening degree is 90 steps. Therefore, when the temperature difference Dg between the discharge temperature and the condensation temperature when the expansion valve opening is 90 steps is read from FIG. In this way, the value of the temperature difference Dg between the discharge temperature and the condensing temperature at which the COP is maximized under the conditions of the specific outside air temperature, the incoming water temperature and the set hot water temperature (for example, 65 ° C.) is 25 ° C. Will be obtained. Accordingly, under the conditions of the specific outside air temperature, the incoming water temperature and the set hot water temperature (for example, 65 ° C.), 25 ° C. is set as the target temperature difference Dg between the discharge temperature and the condensation temperature, and this target temperature difference is set. By adjusting and controlling the opening of the expansion valve 13 so as to be Dg, the heat exchange heating to the set hot water temperature is accurately performed in combination with the control by the compressor control unit 311 while realizing the optimum energy consumption efficiency. Will be able to do. And about the value of such target temperature difference Dg, various external temperature (for example, 0 degreeC-35 degreeC), various incoming water temperature (for example, 5 degreeC-25 degreeC), and various setting hot water temperature (for example, 60 degreeC-80 degree). The target temperature difference Dg obtained by a test under a combination condition of [° C.] is set in the target value table 331 as a relation table with the corresponding combination condition.

  Further, the FF value table 332 is a table in which control amounts at the start of operation for the rotation speed of the compressor 11 and the opening degree of the expansion valve 13 are set in advance as FF values. This FF value is also predetermined in relation to the combination conditions of the outside air temperature, the incoming water temperature, and the set hot water temperature. Accordingly, at the start of operation, the corresponding FF value is calculated based on the detected outside air temperature, the detected incoming water temperature, and the set hot water temperature at that time, and set as the control amount at the start of operation.

  Hereinafter, the hot water temperature control will be described with reference to the flowchart of FIG. First, the rotation speed FF value of the corresponding compressor 11 and the opening of the expansion valve 13 are opened from the FF value table 332 based on the set hot water temperature, the detected incoming water temperature, and the detected outside air temperature set and input to a remote controller (not shown). Similarly, a target temperature difference between the discharge temperature and the condensing temperature corresponding to the target value table 331 is determined based on the set hot water temperature, the detected incoming water temperature, and the detected outside air temperature (step). S1). Further, a target condensation temperature is determined based on the set hot water temperature (step S2). The target condensing temperature is also determined by determining from a table in which the relationship between the preset hot water temperature and the target condensing temperature is determined in advance. That is, if the condensing temperature of the refrigerant at the position of the condensing temperature sensor 17 is how many times, whether or not the temperature of the hot water coming out from the outlet of the hot water supply heat exchanger 12 becomes the set hot water temperature is obtained by a test or calculation in advance. A table defining the relationship between the condensation temperature and the set hot water temperature is stored and set in advance.

  Next, the operation is started by starting the operation of the compressor 11 by the rotation speed FF value and the expansion valve 13 by the opening degree FF value (step S3). Then, the rotational speed (operation control amount) of the compressor 11 is changed and controlled so that the detected condensation temperature becomes the target condensation temperature. That is, if the detected condensing temperature is lower than the target condensing temperature, the rotational speed is increased, and conversely if it is higher, the rotational speed is decreased, and the rotational speed is adjusted so that the detected condensing temperature matches the target condensing temperature. (Step S4). Then, the temperature difference between the detected discharge temperature of the refrigerant discharged from the compressor 11 and the detected condensing temperature is calculated in a state where the rotation speed at that time is kept constant, and the value of the temperature difference becomes the target temperature difference. The opening degree of the expansion valve 13 is changed and controlled (step S5). That is, if the actual temperature difference is larger than the target temperature difference, the opening degree of the expansion valve 13 is opened, and conversely, if the actual temperature difference is smaller, the opening degree of the expansion valve 13 is narrowed to the closing side. Thereby, the temperature difference between the discharge temperature of the refrigerant discharged from the compressor 11 and the condensation temperature in the hot water supply heat exchanger 12 is maintained at the target temperature difference.

  The above steps S4 and S5 are repeated until a stop signal (for example, an operation signal for turning off the operation switch) is output (step S6). When the stop signal is output, the control is terminated.

  According to the tapping temperature control described above, since the rotation speed of the compressor 11 is changed and controlled so that the detected condensing temperature becomes the target condensing temperature (step S4), the gas-liquid is changed from the gas phase by heat exchange with water. Even if a refrigeration cycle is configured using an HC refrigerant that changes phase from a gas / liquid phase to a liquid layer, the temperature control is performed so that the temperature of the hot water by heat exchange heating in the hot water supply heat exchanger 12 becomes the set hot water temperature. can do. In addition, the opening degree of the expansion valve 13 is changed and controlled so that the value of the temperature difference between the detected discharge temperature of the refrigerant discharged from the compressor 11 and the detected condensing temperature becomes the target temperature difference ( Step S5) Even when the HC refrigerant that uses the heat in the latent heat region for heat exchange is used as described above, the COP can be maximized. Further, by repeating the processes of steps S4 and S5, the rotational speed of the compressor 11 is converged to a substantially constant value without being frequently changed. In particular, the operation noise of the compressor 11 is generated during night operation. Can be reduced.

<Implementation form>
Figure 6 shows a controller 3a according to the implementation embodiments. This implementation embodiment only in that with the hot water temperature instead of the condensation temperature which has been used in the control of the reference embodiment, is different from the reference embodiment. The other structure is the same as the reference embodiment, the same configuration as the reference embodiment is omitted by giving the same reference numerals as reference embodiment, without redundant description.

That is, the compressor control section 311a of the first control means constituting the hot water temperature control means 31a of the implementation form, while change control the rotational speed of the compressor 11 so that the detected hot water temperature reaches the set hot water supply temperature, The expansion valve control unit 312a as the second control means is a target temperature in which the temperature difference between the detected discharge temperature and the detected hot water temperature is determined by the target temperature difference determination processing means 32a while maintaining the rotation speed of the compressor 11 constant. The opening degree of the expansion valve 13 is changed and controlled so as to be a difference.

The reason why the tapping temperature can be used instead of the condensing temperature in the reference mode is as follows. For example, as can be seen from the temperature change shown in FIG. 3, when the opening degree of the expansion valve 13 is changed while the rotation speed of the compressor 11 is kept constant, the condensation temperature in the hot water supply heat exchanger 12 is changed. Therefore, a proportional relationship is always maintained while maintaining a difference of about 5 ° C. with the temperature of the hot water discharged to the water circulation pipe 22. Therefore, even with hot water temperature instead of the condensation temperature which has been used in the control in the reference embodiment, it is considered possible to obtain the same advantageous effects as reference embodiment.

The target temperature difference determination processing means 32a is a combination of the discharge temperature from the compressor 11 and the hot water supply in the combination of the detected outside air temperature from the outside air temperature sensor 26 at the current operation time, the detected incoming water temperature from the incoming water temperature sensor 24, and the set hot water temperature. The temperature difference with respect to the temperature of the tapping water from the heat exchanger 12 for use, and the temperature difference at which the energy consumption efficiency is maximized (coefficient of performance: COP is maximized) is determined as the target temperature difference. In this determination process, the target temperature difference is determined from the target value table 331a based on the combination of the detected outside air temperature, the detected incoming water temperature, and the set hot water temperature. In the target value table 331a, the value of the temperature difference between the discharge temperature and the hot water temperature at which the COP is maximized under various combinations of the outside air temperature, the incoming water temperature, and the set hot water temperature is tested in the same manner as in the reference embodiment.・ It may be determined by calculation.

The value of the target temperature difference in the target value table 331a is obtained as follows. First, the changes in the discharge temperature, the tapping temperature, and the condensation temperature when the opening degree of the expansion valve 13 is changed under the same conditions as described in the reference mode are obtained to obtain the test results in FIG. FIG. 4 is obtained as a test result of the amount of output heat and the change in COP at the same conditions, and the opening degree of the expansion valve 13 (90 steps under this condition) that gives the maximum COP is obtained. And the temperature difference Dy (refer FIG. 7) between the discharge temperature in the COP largest expansion valve opening degree-tapping temperature is obtained. Similar to the temperature difference Dy described in the reference embodiment, a combination of various outside air temperatures, various incoming water temperatures, and various set hot water temperatures obtained by a test and corresponding to the obtained target temperature differences Dy. It is set in the target value table 331a as a relation table with conditions. The FF value table 332 is the same as that described in the reference form.

Hereinafter, with reference to a flowchart of FIG. 8, it will be described tapping temperature control of the implementation forms. First, the rotation speed FF value of the corresponding compressor 11 and the opening of the expansion valve 13 are opened from the FF value table 332 based on the set hot water temperature, the detected incoming water temperature, and the detected outside air temperature set and input to a remote controller (not shown). Similarly, a target temperature difference between the discharge temperature and the hot water temperature corresponding from the target value table 331a is determined based on the set hot water temperature, the detected incoming water temperature, and the detected outside air temperature (step). S11).

  Next, the operation is started by starting the operation of the compressor 11 with the rotation speed FF value and the operation of the expansion valve 13 with the opening FF value (step S12). And the rotation speed of the compressor 11 is changed and controlled so that the detected hot water temperature becomes the set hot water temperature. That is, if the detected hot water temperature is lower than the target hot water temperature, the rotational speed is increased, and if it is higher, the rotational speed is decreased, and the rotational speed is adjusted so that the detected hot water temperature matches the set hot water temperature. (Step S13). Then, the temperature difference between the detected discharge temperature of the refrigerant discharged from the compressor 11 and the detected hot water temperature of the hot water discharged from the hot water supply heat exchanger 12 with the rotation speed kept constant is calculated. The opening degree of the expansion valve 13 is changed and controlled so that the temperature difference value becomes the target temperature difference (step S14). That is, if the actual temperature difference is larger than the target temperature difference, the opening degree of the expansion valve 13 is opened, and conversely, if the actual temperature difference is smaller, the opening degree of the expansion valve 13 is narrowed to the closing side. At this time, the rotation speed of the compressor 11 is kept constant. Thereby, the temperature difference between the detected discharge temperature of the refrigerant discharged from the compressor 11 and the detected hot water temperature of the hot water discharged from the hot water supply heat exchanger 12 is maintained at the target temperature difference.

  The above steps S13 and S14 are repeated until a stop signal (for example, an operation signal for turning off the operation switch) is output (step S15). When the stop signal is output, the control is terminated.

In the case of this implementation form, the rotational speed of the compressor 11, since the detection hot water temperature is changed controlled to set the hot water temperature (step S13), and similarly to the reference embodiment, the heat exchange with the water Even if a refrigeration cycle is configured using an HC refrigerant that changes phase from a gas phase to a gas-liquid phase and from a gas-liquid phase to a liquid layer, the tapping temperature by heat exchange heating in the hot water supply heat exchanger 12 is set. The temperature can be controlled so that In addition, the opening degree of the expansion valve 13 is changed and controlled so that the temperature difference between the detected discharge temperature of the refrigerant discharged from the compressor 11 and the detected hot water temperature on the hot water supply circuit 2 side becomes the target temperature difference. (Step S14), the COP is maximized even in the case of using the HC refrigerant that uses the heat in the latent heat region for heat exchange as in the reference mode as described above. become able to. Further, by repeating the processes of steps S13 and S14, the rotation speed of the compressor 11 is converged to a substantially constant value without being frequently changed, and the operation noise of the compressor 11 is generated particularly during night operation. Can be reduced. Furthermore, in the exemplary embodiment, reference embodiment can omit the condensation temperature sensor 17 that is required is, it is possible to achieve also a reduction in the number of components and cost reduction.

<Other reference forms>
In the reference embodiment or the embodiment described above , the compressor control units 311 and 311a, which are first control means, control the compressor 11 to be controlled by changing the rotation speed. The first control means is configured to change and control the incoming water flow rate to the hot water supply heat exchanger 12 with the water supply pump 23 (for example, the number of rotations of the pump drive motor) on the hot water supply circuit 2 side as a control target instead of the compressor 11. things may be adopted as another reference embodiment. In this case, since the hot water can be managed by changing and controlling the operation of the water supply pump 23, the operation control amount (rotation speed) of the compressor 11 is kept constant.

Chi words, the water supply pump control unit and the first control means in place of the compressors controller 311, the water supply pump control unit, detecting the condensation temperature becomes the target condensing temperature determined based on the set hot water supply temperature In this way, the operation control amount (for example, the rotation speed) of the water supply pump 23 is changed and controlled, and the incoming water flow rate to the hot water supply heat exchanger 12 is changed and controlled. In the flowchart of FIG. 5 in this case, in step S4, the rotation speed of the feed water pump 23 may be changed and controlled so that the detected condensation temperature becomes the target condensation temperature. That is, if the detected condensing temperature is lower than the target condensing temperature, the incoming water flow rate is reduced (lowering the rotation speed of the feed water pump 23), and conversely, if the detected condensing temperature is higher, the incoming water flow rate is increased (increasing the rotating speed). The water flow rate to the hot water supply heat exchanger 12 is adjusted so that the detected condensing temperature matches the target condensing temperature.

Further, the first control unit the water supply pump control unit in place of the compressors controller 311a, the water supply pump control unit, operation control amount of the water supply pump 23 so that the detected hot water temperature reaches the set hot water supply temperature (rotation speed ) Is changed and controlled, and the incoming water flow rate to the hot water supply heat exchanger 12 is changed and controlled. And in the flowchart of FIG. 8, what is necessary is just to change-control the rotation speed of the feed water pump 23 so that a detection hot water temperature may turn into a preset hot water temperature in the step S13. That is, if the detected hot water temperature is lower than the set hot water temperature, the incoming water flow rate is reduced (lowering the rotational speed of the feed water pump 23), and conversely, if the detected hot water temperature is higher, the incoming water flow rate is increased (increasing the rotational speed). And adjusting the flow rate of incoming water to the hot water supply heat exchanger 12 so that the detected hot water temperature matches the set hot water temperature.

  As described above, when the control target is changed from the compressor 11 to the water supply pump 23, the operation control amount (the number of rotations) of the compressor 11 can be kept constant while the operation of the water supply pump 23 is changed and controlled. It is possible to eliminate the generation of noise accompanying the change in the rotation speed of the compressor 11. This is particularly useful at night when the surroundings are quiet. The reason why the operation and effect similar to that of changing and controlling the operation of the compressor 11 can be obtained by changing and controlling the operation of the feed water pump 11 is as follows. That is, FIG. 9 shows the discharge temperature from the compressor 11 when the water supply flow rate to the hot water supply heat exchanger 12 is changed by changing the rotation speed of the water supply pump 23 while maintaining the rotation speed of the compressor 11 constant. And changes in the condensation temperature in the hot water supply heat exchanger 12 were measured by tests. According to the test results of FIG. 9, even if the rotational speed of the compressor 11 is kept constant by changing the incoming water flow rate, the refrigerant discharge temperature from the compressor 11 and the refrigerant in the hot water supply heat exchanger 12 The condensing temperature can be changed almost linearly. Accordingly, the temperature of the hot water can be controlled by changing and controlling the incoming water flow rate to the hot water supply heat exchanger 12 with the water supply pump 23 as a control object instead of the compressor 11.

<Other embodiments>
In the above implementation form is used propane as HC-based refrigerant, Ru can be used, for example isobutane or propylene as HC refrigerants In addition.

DESCRIPTION OF SYMBOLS 1 Refrigerant circulation circuit 2 Hot water supply circuit 11 Compressor 12 Heat exchanger 13 for hot water supply Expansion valve (pressure reduction means)
14 heat exchanger 15 refrigerant circulation pipe 16 discharge temperature sensor for the heat source (discharge temperature detection hand stage)
2 3 Water supply pump 24 Water temperature sensor (water temperature detection means)
25 Hot water temperature sensor (hot water temperature detection means)
26 Outside air temperature sensor (outside air temperature detecting means)
3 2a target temperature difference determination processing means
3 11a Compressor control section (first control means)
3 12a Expansion valve controller (second control means)

Claims (2)

A refrigerant circulation circuit in which a compressor, a hot water supply heat exchanger, a decompression unit, and a heat source heat exchanger are sequentially connected by a refrigerant circulation pipe; and water supplied to the hot water supply heat exchanger by a water supply pump heat exchanger heated by the refrigerant discharged from the compressor Te heat pump water heater smell and a hot water supply circuit for tapping, the
HC refrigerant is used as the refrigerant circulated in the refrigerant circuit,
A discharge temperature detection means for detecting the discharge temperature of the refrigerant discharged from the pre-Symbol compressor,
An outside air temperature detecting means for detecting the outside air temperature;
An incoming water temperature detecting means for detecting an incoming water temperature entering the hot water heat exchanger ;
A tapping temperature detecting means for detecting a temperature of hot water that is heated by heat exchange by passing through the heat exchanger for hot water supply;
And the discharge temperature of the refrigerant discharged from the pre-Symbol compressor, a temperature difference between the hot water temperature of the hot water to be tapped from the heat exchanger for the hot water supply, a detecting outside air temperature detected by the outside air temperature detection means A target temperature difference determination processing means for determining a target temperature difference corresponding to a detected incoming water temperature detected by the incoming water temperature detecting means and a set hot water temperature;
As detected hot water temperature detected by the hot water temperature detecting means is the set hot water temperature, a first control means for changing control of the operation control amount before Symbol compressor,
Wherein a detection discharge temperature detected by the discharge temperature detecting means, wherein as the temperature difference between the detected hot water temperature reaches the target temperature difference determined by the target temperature difference determination processing means, the operation control of the pressure reducing means e Bei and second control means for changing control the amount,
The first control means changes and controls the operation control amount of the compressor. Next, the second control means reduces the pressure reduction while maintaining the operation of the compressor constant with the change-controlled operation control amount. A heat pump water heater characterized by being configured to change and control the operation control amount of the means . The heat pump water heater according to claim 1 ,
The target temperature difference determination processing means is configured to determine, as the target temperature difference, a value of the temperature difference that maximizes energy consumption efficiency on the refrigerant circulation circuit side with respect to the operation amount of the compressor. Water heater.

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