JP2005188923A - Heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump water heater capable of performing an efficient hot water supply heating operation throughout the year. <P>SOLUTION: This heat pump water heater comprises a refrigerant circulating circuit including a compressor 1, a refrigerant-water heat exchanger 2, a pressure reducing device 3 and an evaporator 4; a hot water supply circuit including a hot water storage tank 5, a circulating pump 6 and a refrigerant-water heat exchanger 2; an outside temperature detection means 12 detecting the outside air temperature, a discharge temperature detection means 13 detecting the discharge temperature of the compressor 1; and a control means 11 controlling the opening of the pressure reducing device 3 so that the discharge temperature of the compressor 1 reaches a target discharge temperature preset to the outside air temperature. The circulating quantity of hot water carried in the hot water supply circuit is controlled to make the temperature of the water-side outlet of the heat exchanger 2 substantially constant, and the higher the outside temperature is, the higher the target discharge temperature of the compressor is. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat pump water heater.

A conventional heat pump water heater of this type is disclosed in Japanese Patent Laid-Open No. 60-164157. FIG. 14 is a diagram illustrating the configuration of a conventional heat pump water heater. In FIG. 14, a refrigerant circulation circuit including a compressor 1, a refrigerant-to-water heat exchanger 2, a decompression device 3, and an evaporator 4, a hot water tank 5, a circulation pump 6, the refrigerant-to-water heat exchanger 2, and an auxiliary heater The high-temperature and high-pressure superheated gas refrigerant discharged from the compressor 1 is connected to the refrigerant-to-water heat exchanger 2 where the water sent from the circulation pump 6 is heated. . The condensed and liquefied refrigerant is decompressed by the decompression device 3 and flows into the evaporator 4, where it absorbs atmospheric heat to evaporate and returns to the compressor 1. On the other hand, the hot water heated in the refrigerant-to-water heat exchanger 2 flows into the upper part of the hot water storage tank 5 and is gradually stored from above. When the inlet water temperature of the refrigerant-to-water heat exchanger 2 reaches a set value, the water temperature detecting means 8 detects it, stops the heat pump operation by the compressor 1, and switches to the auxiliary operation of the auxiliary heater 7. Is.
JP 60-164157 A

  In the conventional heat pump water heater shown in FIG. 14, a capillary tube or a temperature type expansion valve is used as the decompression device 3. When a capillary tube is used as the decompression device 3, the specification of the capillary tube is generally designed based on the summer temperature conditions in which the refrigerant circulation amount is large. For this reason, there is a problem that the operation efficiency is deteriorated in the winter season when the hot water supply load is particularly large except the summer season. Similarly, during the winter when the outside air temperature is low except during the summer, more refrigerant than necessary is circulated in the refrigerant circulation circuit, so that the liquid refrigerant is sucked into the compressor 1, resulting in liquid compression and the durability of the compressor. Had the problem of getting worse.

  On the other hand, when a temperature expansion valve is used as the decompression device 3, generally, the specification of the temperature expansion valve as the decompression device 3 is such that the refrigerant at the outlet of the evaporator 4 is in a superheated gas state with a superheat degree. To design. Therefore, there has been a problem that the discharge pressure rises when the temperature is higher than the designed outside air temperature, or the discharge temperature rises in winter when the outside air temperature is low, and the durability of the compressor deteriorates. Further, even when the evaporator 4 is frosted in winter, the refrigerant state at the outlet of the evaporator 4 is controlled so that the degree of superheat can be obtained, so that frosting further proceeds and the efficiency of operation is deteriorated. It was.

  An object of the present invention is to realize an efficient hot water supply heating operation without an abnormal temperature rise and abnormal pressure rise of a compressor.

  In order to solve the above problems, the present invention provides a refrigerant circulation circuit having a compressor, a refrigerant-to-water heat exchanger, a decompression device, and an evaporator, a hot water tank, a circulation pump, and a hot water supply circuit having the refrigerant-to-water heat exchanger. An outside air temperature detecting means for detecting the outside air temperature, a discharge temperature detecting means for detecting the discharge temperature of the compressor, and a pressure reduction so that the discharge temperature of the compressor becomes a target discharge temperature set in advance with respect to the outside air temperature. Control means for controlling the opening degree of the apparatus, controlling the circulation amount of the hot water flowing through the hot water supply circuit so that the temperature of the water-side outlet of the refrigerant-to-water heat exchanger is substantially constant, A heat pump water heater that lowers the target discharge temperature of the compressor as the outside air temperature increases.

  In the above invention, a discharge temperature with the highest efficiency of the hot water supply operation with respect to the outside air temperature is obtained in advance, and this is set as the target discharge temperature. Then, when performing a hot water supply operation, the outside air temperature and the discharge temperature of the compressor are detected, the opening of the decompression device is controlled so that the discharge temperature of the compressor becomes the target discharge temperature, and the outside air temperature is high. The target discharge temperature of the compressor is lowered, so that efficient hot water heating operation can be performed throughout the year.

  As described above, the heat pump water heater of the present invention has an effect that an efficient hot water heating operation can be performed throughout the year.

  The present invention detects a refrigerant circulation circuit having a compressor, a refrigerant-to-water heat exchanger, a decompression device, an evaporator, a hot water tank, a circulation pump, a hot water supply circuit having the refrigerant-to-water heat exchanger, and an outside air temperature. The outside air temperature detecting means, the discharge temperature detecting means for detecting the discharge temperature of the compressor, and the opening degree of the decompression device are controlled so that the discharge temperature of the compressor becomes a target discharge temperature set in advance with respect to the outside air temperature. Control means for controlling the circulation amount of hot water flowing through the hot water supply circuit so that the temperature of the water-side outlet of the refrigerant-to-water heat exchanger becomes substantially constant, and the higher the outside air temperature, the more the compression is performed. By lowering the target discharge temperature of the machine, the discharge temperature with the best efficiency of the hot water supply operation with respect to the outside air temperature is obtained in advance, and this is set as the target discharge temperature. I can drive .

  Embodiments of the present invention will be described below with reference to the drawings.

(Example 1)
FIG. 1 is a diagram illustrating the configuration of a heat pump water heater according to a first embodiment of the present invention, FIG. 2 is a diagram illustrating discharge temperature, discharge pressure, and efficiency with respect to the opening of a decompression device of the heat pump water heater, and FIG. It is explanatory drawing which shows the target discharge temperature with respect to the external temperature of a machine. In addition, the same code | symbol is used for the same component as FIG. 14 demonstrated in the prior art example, and description is abbreviate | omitted.

  In FIG. 1, the rotation speed control means 10 controls the rotation speed of the circulation pump 6 by a signal from the boiling temperature detection means 9 provided at the water-side outlet of the refrigerant-to-water heat exchanger 2, and the refrigerant-to-water heat The outlet water temperature (boiling temperature) of the exchanger 2 is boiled so as to be substantially constant. Further, the control unit 11 controls the decompression device 3 with signals from the outside temperature detection unit 12 that detects the outside air temperature and the discharge temperature detection unit 13 that detects the discharge temperature of the compressor 1. Reference numeral 14 denotes first storage means for storing a target discharge temperature with respect to the outside air temperature. The decompression device 3 includes an electric expansion valve (not shown).

  Next, the operation and action will be described. In FIG. 2, the opening of the decompression device 3 is taken on the horizontal axis, and the discharge temperature, the discharge pressure, and the efficiency are taken on the vertical axis. It shows the relationship. As can be seen from the figure, the efficiency has a maximum value with respect to the opening of the decompression device 3. In the figure, the alternate long and short dash line indicates the maximum normal discharge temperature, which is the maximum temperature during normal use of the compressor, and the double dotted line indicates the maximum normal discharge pressure, which is the maximum pressure during normal use of the compressor. ing. Here, the discharge temperature with respect to the opening degree X of the pressure reducing device 3 at which the efficiency is maximized is defined as a target discharge temperature Y. And when this target discharge temperature Y is calculated | required with respect to each external temperature, it will become like FIG. As is apparent from FIG. 3, the target discharge temperature of the compressor is lowered as the outside air temperature increases. Then, the relationship between the target discharge temperature and the outside air temperature is stored in the first storage unit 14 in advance.

  That is, when the hot water supply operation starts and the compressor 1 is started, the control unit 11 detects the outside air temperature and the discharge temperature based on signals from the outside air temperature detection unit 12 and the discharge temperature detection unit 13. If the current discharge temperature is higher than the target discharge temperature in the information from the first storage unit 14 storing the relationship between the outside air temperature and the target discharge temperature, the control unit 11 opens the opening of the decompression device 3. To increase (opening direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  As described above, if the discharge temperature control by the control means 11 is performed every certain time, an efficient hot water supply operation can always be performed even if the outside air temperature changes.

(Example 2)
4 is a diagram illustrating the configuration of the heat pump water heater according to the second embodiment of the present invention, FIG. 5 is a diagram illustrating the discharge temperature, the discharge pressure, and the efficiency with respect to the opening of the decompression device of the heat pump water heater, and FIG. It is explanatory drawing which shows the discharge pressure with respect to the external temperature of an apparatus, and the opening degree of a decompression device.

  The present embodiment is different from the first embodiment in that the pressure detecting means 15 is provided on the discharge side of the compressor 1. In addition, the part of the same code | symbol as Example 1 has the same structure, and abbreviate | omits description.

  Next, the operation and action will be described. In FIG. 5, the opening of the decompression device 3 is taken on the horizontal axis, and the discharge temperature, the discharge pressure, and the efficiency are taken on the vertical axis. This shows the relationship. As shown in the figure, when the outside air temperature becomes considerably high, the discharge pressure sometimes exceeds the normal maximum discharge pressure (for example, 2.4 MPa) at the opening of the decompression device 3 at which the efficiency reaches a maximum value. In this case, when the opening degree of the decompression device 3 is changed from A to B, the discharge pressure decreases from C to D.

  That is, when the hot water supply operation is started and the compressor 1 is started, the control means 11 detects the discharge pressure by the signal from the pressure detection means 15. If this discharge pressure is lower than the normal maximum discharge pressure (for example, 2.4 MPa), the control means 11 detects the outside air temperature and the discharge temperature by signals from the outside air temperature detection means 12 and the discharge temperature detection means 13, and If the current discharge temperature is higher than the target discharge temperature in the information from the first storage unit 14 storing the relationship between the outside air temperature and the target discharge temperature, the control unit 11 increases the opening of the decompression device 3. Control to do (opening direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  On the other hand, if the discharge pressure detected by the signal from the pressure detection means 15 is higher than the normal maximum discharge pressure (for example, 2.4 MPa), the control means 11 controls to increase the opening of the decompression device 3 (in the opening direction). To do.

  FIG. 6 shows changes in the discharge pressure and the opening degree of the decompression device 3 with respect to the outside air temperature, with the outside air temperature on the horizontal axis and the discharge pressure and the opening degree of the decompression device 3 on the vertical axis. In the same figure, if the outside air temperature becomes high, it is possible to prevent the discharge pressure from exceeding the normal maximum discharge pressure by performing the control by the discharge pressure as described above. In this way, a hot water supply operation without an abnormal pressure increase is possible. In addition, the dotted line in a figure is the case of control by the discharge temperature demonstrated in Example 1, and symbol A, B, C, D respond | corresponds to the same symbol of FIG.

(Example 3)
FIG. 7 is a diagram illustrating the configuration of a heat pump water heater according to a third embodiment of the present invention, FIG. 8 is a diagram illustrating discharge temperature, discharge pressure, and efficiency with respect to the opening of the decompression device of the heat pump water heater, and FIG. It is explanatory drawing which shows the target discharge temperature with respect to the external temperature of a machine.

  The present embodiment is different from the second embodiment in that the outside temperature detecting means 12 and the discharge temperature detecting means 13 are used as the pressure detecting means, and the second storage means 16 is further provided. In addition, the part of the same code | symbol as Example 2 has the same structure, and description is abbreviate | omitted.

  Next, the operation and action will be described. In FIG. 8, the opening of the decompression device 3 is taken on the horizontal axis, and the discharge temperature, the discharge pressure, and the efficiency are taken on the vertical axis. This shows the relationship. As shown in the figure, when the outside air temperature becomes considerably high, the discharge pressure sometimes exceeds the normal maximum discharge pressure (for example, 2.4 MPa) at the opening of the decompression device 3 at which the efficiency reaches a maximum value. In this case, when the opening degree of the decompression device 3 is changed from A to B, the discharge pressure decreases from C to D, and the discharge temperature decreases from E to F. Eventually, in the case of the outside air temperature shown in the figure, in order to set the discharge pressure to D, the discharge temperature may be set to F. The discharge temperature with respect to the opening degree B of the decompression device 3 is set as a target discharge temperature Z. And when this target discharge temperature Z is calculated | required with respect to each external temperature, it will become like the continuous line of FIG. The relationship between the target discharge temperature Z and the outside air temperature is stored in advance in the second storage unit 16. In the figure, a dotted line is the case of control by the discharge temperature demonstrated in Example 1, and let the external temperature of the intersection of a solid line and a dotted line be the high temperature side limit external temperature Tu.

  That is, when the hot water supply operation is started and the compressor 1 is started, the control unit 11 detects the outside air temperature by a signal from the outside air temperature detecting unit 12. If the outside air temperature is lower than the high temperature side limit outside air temperature Tu, the control means 11 further detects the outside air temperature and the discharge temperature by signals from the outside air temperature detecting means 12 and the discharge temperature detecting means 13, and the outside air temperature is detected. If the current discharge temperature is higher than the target discharge temperature by the information from the first storage means 14 storing the relationship between the target discharge temperature and the target discharge temperature, the control means 11 increases the opening of the decompression device 3 ( Open direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  On the other hand, if the outside air temperature detected by the signal from the outside air temperature detecting means 12 is higher than the high temperature side limit outside air temperature Tu, the discharge temperature is detected by the signal from the discharge temperature detecting means 13, and the second storage means 16 is used. If the current discharge temperature is higher than the target discharge temperature, the control means 11 performs control to increase the opening of the decompression device 3 (in the opening direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  If the discharge temperature control by the control means 11 is performed at a certain time as described above, it is possible to prevent the discharge pressure from exceeding the normal maximum discharge pressure by performing the control based on the discharge temperature, so there is no abnormal pressure increase. Hot water supply operation is possible.

Example 4
FIG. 10 is a diagram illustrating the configuration of a heat pump water heater according to a fourth embodiment of the present invention, FIG. 11 is a diagram illustrating discharge temperature, discharge pressure, and efficiency with respect to the opening of the decompression device of the heat pump water heater, and FIG. It is explanatory drawing which shows the target discharge temperature with respect to the external temperature of a machine.

  The present embodiment is different from the first embodiment in that the third storage unit 17 is provided. In addition, the part of the same code | symbol as Example 1 has the same structure, and abbreviate | omits description.

  Next, the operation and action will be described. FIG. 11 shows the opening temperature of the decompression device 3 on the horizontal axis and the discharge temperature, discharge pressure, and efficiency on the vertical axis, and the discharge temperature, discharge pressure, and efficiency with respect to the opening of the decompression device 3 when a certain outside air temperature is low. This shows the relationship. As shown in the figure, when the outside air temperature becomes considerably low, the discharge temperature sometimes exceeds the normal maximum discharge temperature (for example, 105 ° C.) at the opening of the decompression device 3 at which the efficiency reaches a maximum value. In this case, when the opening degree of the decompression device 3 is changed from A to B, the discharge temperature decreases from C to D. FIG. 12 shows the relationship of the target discharge temperature W with respect to the outside air temperature, with the outside air temperature on the horizontal axis and the target discharge temperature on the vertical axis. As shown by the solid line in the figure, the target maximum discharge temperature W (for example, 105 ° C.) is constant as the target discharge temperature W in the case of the low outside air temperature. The relationship between the target discharge temperature W and the outside air temperature is stored in advance in the third storage unit 17. Also, the dotted line in the figure shows the case of control by the discharge temperature described in the first embodiment, and the outside air temperature at the intersection of the solid line and the dotted line is the low limit side outside air temperature Tl.

  That is, when the hot water supply operation is started and the compressor 1 is started, the control unit 11 detects the outside air temperature by a signal from the outside air temperature detecting unit 12. If the outside air temperature is higher than the low-temperature side limit outside air temperature Tl, the control means 11 detects the discharge temperature by a signal from the discharge temperature detecting means 13 and stores the relationship between the outside air temperature and the target discharge temperature. If the current discharge temperature is higher than the target discharge temperature based on the information from the first storage means 14, the control means 11 performs control so that the opening degree of the decompression device 3 is increased (in the opening direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  On the other hand, if the outside air temperature detected by the signal from the outside air temperature detecting means 12 is lower than the low limit side outside air temperature Tl, the control means 11 detects the discharge temperature by the signal from the discharge temperature detecting means 13, and the outside air temperature If the current discharge temperature is higher than the target discharge temperature by the information from the third storage means 17 storing the relationship between the target discharge temperature and the target discharge temperature, the control means 11 increases the opening of the decompression device 3 ( Open direction). Conversely, if the current discharge temperature is lower than the target discharge temperature, the control means 11 performs control so that the opening degree of the decompression device 3 is reduced (in the closing direction).

  If the discharge temperature control by the control means 11 is performed at certain intervals as described above, the discharge temperature can be prevented from exceeding the normal maximum discharge temperature, so that a hot water supply operation without an abnormal temperature rise is possible.

(Example 5)
FIG. 13 is a configuration explanatory diagram of a heat pump water heater according to a fifth embodiment of the present invention. In the present embodiment, the difference from the first embodiment is that a minimum opening storage means 18 for storing the minimum opening of the decompression device 3 is provided. In addition, the part of the same code | symbol as Example 1 has the same structure, and abbreviate | omits description.

  Next, the operation and action will be described. When the hot water supply operation is started and the compressor 1 is started, the control unit 11 detects the outside air temperature and the discharge temperature based on signals from the outside air temperature detecting unit 12 and the discharge temperature detecting unit 13. If the current discharge temperature is higher than the target discharge temperature in the information from the first storage unit 14 storing the relationship between the outside air temperature and the target discharge temperature, the control unit 11 opens the opening of the decompression device 3. To increase (opening direction). On the contrary, if the current discharge temperature is lower than the target discharge temperature, the control means 11 determines the minimum opening degree of the decompression device 3 and the current opening degree of the decompression device 3 obtained from the signal from the minimum opening degree storage means 18. Compare. And if the opening degree of the present decompression device 3 is larger than the minimum opening degree, the opening degree of the decompression device 3 is controlled to be smaller (in the closing direction) within a range that does not fall below the minimum opening degree. Further, if the current opening of the decompression device 3 is smaller than or equal to the minimum opening, the opening of the decompression device 3 is controlled to be the minimum opening.

  In this way, when the outside air temperature is low, even if frost adheres to the evaporator 4 and the discharge temperature or the evaporation temperature decreases, the opening of the decompression device 3 is not reduced more than necessary. Good hot water heating operation can be maintained.

  As described above, the heat pump water heater according to the present invention is particularly useful for a hot water storage type heat pump water heater having a hot water storage tank, but can also be applied to a shape in which a hot water storage tank and a heat pump circuit are integrated.

Structure explanatory drawing which shows the heat pump water heater of Example 1 of this invention Explanatory drawing which shows discharge temperature with respect to the opening degree of the decompression device of the same heat pump water heater, discharge pressure, and efficiency Explanatory drawing which shows the target discharge temperature with respect to the outside temperature of the heat pump water heater Structure explanatory drawing of the heat pump water heater of Example 2 of this invention Explanatory drawing which shows discharge temperature with respect to the opening degree of the decompression device of the same heat pump water heater, discharge pressure, and efficiency Explanatory drawing which shows the discharge pressure with respect to the external temperature of the heat pump water heater, and the opening degree of a decompression device Structure explanatory drawing of the heat pump water heater of Example 3 of this invention Explanatory drawing which shows discharge temperature with respect to the opening degree of the decompression device of the same heat pump water heater, discharge pressure, and efficiency Explanatory drawing which shows the target discharge temperature with respect to the outside temperature of the heat pump water heater Structure explanatory drawing of the heat pump water heater of Example 4 of this invention Explanatory drawing which shows discharge temperature with respect to the opening degree of the decompression device of the same heat pump water heater, discharge pressure, and efficiency Explanatory drawing which shows the target discharge temperature with respect to the outside temperature of the heat pump water heater Structure explanatory drawing of the heat pump water heater of Example 5 of this invention Configuration explanatory diagram of a heat pump water heater in a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Refrigerant to water heat exchanger 3 Pressure reducing device 4 Evaporator 5 Hot water storage tank 6 Circulating pump 11 Control means 12 Outside air temperature detection means 13 Discharge temperature detection means 14 First storage means 15 Pressure detection means 16 Second memory Means 17 Third memory means 18 Minimum opening degree memory means

Claims (1)

Compressor, refrigerant-to-water heat exchanger, decompression device, refrigerant circulation circuit having evaporator, hot water storage tank, circulation pump, hot-water supply circuit having said refrigerant-to-water heat exchanger, and outside air temperature detecting means for detecting outside air temperature Discharge temperature detection means for detecting the discharge temperature of the compressor; and control means for controlling the opening of the decompression device so that the discharge temperature of the compressor becomes a target discharge temperature preset with respect to the outside air temperature; The amount of hot water flowing through the hot water supply circuit is controlled so that the temperature of the water-side outlet of the refrigerant-to-water heat exchanger becomes substantially constant, and the target discharge of the compressor increases as the outside air temperature increases. A heat pump water heater that lowers the temperature.

Images