JP2015127612A - Water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water supply device capable of enlarging an operation range from a single stage compression to multi-stage compression while improving operation efficiency.SOLUTION: A hot water supply device has a refrigeration cycle forming a refrigerant flow channel by successively connecting a plurality of compressors 2, 3 connected in series so that multi-stage compression can be implemented, first and second four-way valves 12, 6 switching a heating operation or a defrosting operation by switching a circulating direction of a refrigerant, a water heat exchanger 7 for heating water by condensation latent heat of the refrigerant, first and second expansion valves 8, 10, and an air heat exchanger 11 by refrigerant pipes 13, for circulating the refrigerant. Further the first four-way valve 12 is disposed to switch a part of the refrigerant flow channel so that the refrigerant returning to a suction port side of the compressor is returned to the suction port side of the compressor in compressing operation, while bypassing the compressor in stopping the compressing operation, when the compressing operation of a part of the plurality of compressors is stopped.

Description

  Embodiments of the present invention relate to a heat pump hot water supply apparatus including a plurality of compressors, and more particularly to a hot water supply apparatus capable of switching between a single-stage compression operation and a multistage compression operation.

  Conventionally, as an example of this type of heat pump type hot water supply apparatus, one having a two-stage compressor is known (see, for example, Patent Document 1).

  On the other hand, in a hot water supply apparatus equipped with a single-stage compression refrigeration cycle, when the hot water temperature approaches the set temperature, the heating capacity is suppressed, and a relatively high efficiency operation becomes possible.

JP 2001-241780 A

  However, in the hot water supply apparatus equipped with the conventional two-stage compressor, since it is two-stage compression, it is difficult to operate to suppress the heating capacity as compared with the hot water supply apparatus of a single-stage compression refrigeration cycle. There is a problem that the operable range is narrowed.

  Moreover, in the conventional hot water supply apparatus, when performing the defrost operation which reverses a refrigerant | coolant circulation direction to a reverse direction with the heating operation by switching operation of a four-way valve, a water heat exchanger acts as an evaporator.

  For this reason, since the refrigerant absorbs heat from the water (hot water) at the time of evaporation in this water heat exchanger and is used for defrosting, there is a risk that the water extraction temperature (hot water temperature) of the water heat exchanger may be lowered. .

  The problem to be solved by the present invention is to provide a hot water supply apparatus capable of expanding the operation range from single-stage compression to multi-stage compression while improving the operation efficiency.

  A hot water supply apparatus according to an embodiment includes a plurality of compressors connected in series so as to be capable of multistage compression, a four-way valve that switches to a heating operation or a defrosting operation by switching a refrigerant circulation direction, a water heat exchanger, an expansion means, and air It has a refrigeration cycle in which a heat exchanger is sequentially connected by a refrigerant pipe to form a refrigerant flow path for circulating the refrigerant.

  In addition, when the compression operation of a part of the plurality of compressors is stopped, the refrigerant returning to the compressor suction port side bypasses the compressor stopped during the compression operation, and the compressor suction port during the compression operation Switching means for switching a part of the refrigerant flow path so as to return to the side.

The refrigerating cycle figure at the time of the two-stage heating operation of the hot water supply apparatus which concerns on 1st Embodiment. The refrigerating cycle figure at the time of the single stage heating operation of the hot water supply apparatus which concerns on 1st Embodiment. The Mollier diagram at the time of the single stage heating operation of the water heater according to the first embodiment shown in FIG. The Mollier diagram at the time of the two-stage heating operation of the water heater according to the first embodiment shown in FIG. The refrigeration cycle figure at the time of the single stage defrost operation of the hot-water supply apparatus which concerns on 1st Embodiment. The refrigeration cycle figure at the time of the 3 step | paragraph heating operation of the hot water supply apparatus which concerns on 2nd Embodiment. The refrigeration cycle figure at the time of the single stage heating operation of the hot water supply apparatus which concerns on 2nd Embodiment. The refrigeration cycle figure at the time of the two-stage defrost operation of the hot water supply apparatus which concerns on 3rd Embodiment. The refrigeration cycle figure at the time of the single stage defrost operation of the hot-water supply apparatus which concerns on 3rd Embodiment. The refrigeration cycle figure at the time of the single stage heating operation of the hot water supply apparatus which concerns on 4th Embodiment. The refrigeration cycle figure at the time of the single stage defrost operation of the hot-water supply apparatus which concerns on 4th Embodiment. The Mollier diagram at the time of the two-stage defrosting operation of the hot water supply device according to the third embodiment shown in FIG. The Mollier diagram at the time of the single stage defrosting operation of the water heater according to the third embodiment shown in FIG.

  Hereinafter, a hot water supply apparatus according to an embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent part in several drawings.

[First Embodiment]
(Two-stage heating operation)
FIG. 1 is a refrigeration cycle diagram during a two-stage heating operation by the hot water supply apparatus 1 according to the first embodiment. As shown in FIG. 1, a hot water supply apparatus 1 is configured to be capable of two-stage (multi-stage) compression by connecting a plurality of, for example, two compressors 2 and 3 such as a rotary compressor in series by a connecting pipe 4. Yes. That is, the connecting pipe 4 connects the refrigerant suction port side 3b of the second compressor 3 on the high stage side to the refrigerant discharge port 2a of the first compressor 2 on the low stage side, and the three-way valve 5 in the middle thereof. Is intervening.

  The hot water supply device 1 includes a discharge port 3a of the second compressor 3, a second four-way valve 6, a condenser 7a of the water heat exchanger 7, a first expansion valve 8, a gas-liquid separator 9, a second 2 expansion valve 10, air heat exchanger 11 provided with heat exchange promoting fan 11a, first four-way valve 12 as an example of switching means, and suction port side 2b of first compressor 2 are connected to refrigerant pipe 13 Are connected in sequence to form a refrigerant circulation passage for circulating the refrigerant through the refrigerant pipe 13.

  The second four-way valve 6 can switch the refrigeration cycle to the heating operation or the defrosting operation by switching the circulation direction of the refrigerant circulation passage.

  That is, as shown in FIG. 1, the second four-way valve 6 is configured such that the flow path of the discharged refrigerant discharged from the second (higher stage) compressor 3 is the water heat exchanger 7 as shown by the solid line arrow in the figure. By switching to the inlet side of the condenser 7a, the refrigeration cycle can be heated.

  In addition, as shown by broken line arrows in FIG. 5, the refrigerant discharged from the second compressor 3 is switched to the air heat exchanger 11 by switching the first and second four-way valves 12 and 6, thereby The defrosting operation can be performed by reversing the circulation direction in the direction opposite to the circulation direction of the heating operation.

  As shown in FIG. 1, the water heat exchanger 7 has a condenser 7a through which the high-temperature and high-pressure gas refrigerant is passed. By the heat radiation of the condensation latent heat of the high-temperature and high-pressure gas refrigerant flowing into the condenser 7a, the water heat exchanger 7a It is a heater that boils water into hot water. That is, the water heat exchanger 7 is configured to exchange heat between water flowing through the water passage 7b and refrigerant flowing through the condenser 7a.

  The water passage 7b has a water inlet and a water outlet that is a water outlet, and the water supply pipe 14 is connected to the water inlet, while the hot water pipe 15 is connected to the outlet. One end of the water supply pipe 14 is connected to a water supply source (not shown), and a water supply temperature sensor 16 for detecting the temperature of the water supply is provided in the vicinity of the water inlet of the water heat exchanger 7.

  The hot water supply pipe 15 is provided with a hot water supply port at one end thereof, and a hot water temperature sensor 17 for detecting the hot water temperature is provided in the vicinity of the hot water outlet of the water heat exchanger 7.

  The gas-liquid separator 9 includes an injection pipe 18 having an opening 18a that opens to the inner surface of the upper end. The injection pipe 18 connects the refrigerant outlet end to the refrigerant suction port side 3b of the second compressor 3 via the first and second four-way valves 12 and 6, and connects the first four-way valve 12 and the gas inlet. A liquid refrigerant temperature sensor 19 is provided in the injection pipe 18 between the liquid separators 9.

  The first four-way valve 12 guides the gas refrigerant from the injection pipe 18 to the second four-way valve 6, and guides the gas refrigerant from the air heat exchanger 11 to the refrigerant inlet side 2 b of the first compressor 2. It has a function.

  As shown in FIGS. 2 and 5, the first four-way valve 12 is used when one of the first and second compressors 2 and 3, for example, the first compressor 2, stops the compression operation. The compressor 2 that has been stopped has a function of switching the refrigerant flow path so as to be disconnected from the refrigerant circulation flow path of the refrigeration cycle.

  Therefore, as shown in FIG. 2, for example, when the compression operation of the first compressor 2 is stopped, the gas refrigerant flowing out of the air heat exchanger 11 by the first four-way valve 12 is changed to the first stopped state. The refrigerant circulation channel can be switched so as to bypass the compressor 2 and guide it to the suction port side 3b of the second compressor 3 in operation.

  The liquid refrigerant temperature sensor 19, the feed water temperature sensor 16, and the tapping temperature sensor 17 are electrically connected to the controller 20 via a signal line (not shown), and the liquid refrigerant temperature, the feed water temperature, and the tapping temperature are controlled by the controller 20. Always monitored.

  The controller 20 is constituted by a microcomputer or the like, and includes a CPU, a ROM, a RAM, and a memory, and is electrically connected to each inverter (not shown) of the first and second compressors 2 and 3 and the fan 11a. The number of revolutions per unit time is controlled based on the set value of the hot water supply temperature.

  The controller 20 is electrically connected to the three-way valve 5 and the first and second expansion valves 8 and 10 via signal lines (not shown) to control the opening / closing or opening of these valves. Further, the controller 20 is electrically connected to the first and second four-way valves 12 and 6 through signal lines, and controls the switching operation of the first and second four-way valves 12 and 6 to heat them. Run or defrost.

  FIG. 1 shows a refrigeration cycle during a two-stage heating operation of the water heater 1 configured as described above.

  That is, at this time, the controller 20 switches the first and second four-way valves 12 and 6 so that the circulation direction of the refrigerant circulating in the refrigeration cycle circulates in the solid line direction in FIG.

  As a result, the high-temperature and high-pressure discharged refrigerant compressed by the first compressor 2 is guided to the opened three-way valve 5 and the connecting pipe 4 and introduced into the second compressor 3 through the suction port side 3b. Here, it is further compressed and compressed in two stages. For this reason, the temperature and pressure of the refrigerant increase by two levels.

  The two-stage compressed high-temperature and high-pressure discharged refrigerant is guided by the second four-way valve 6 and flows into the condenser 7a of the water heat exchanger 7, where it dissipates heat and heats the water flowing through the water passage 7b. Boil in hot water. The hot water is discharged into a hot water storage tank (not shown) through a hot water discharge pipe 15, for example. The hot water in the hot water storage tank is supplied again to the water passage 7b of the water heat exchanger 7 through the water supply pipe 14, and is heated by the condensation latent heat of the high-temperature and high-pressure refrigerant flowing through the condenser 7a. By repeating this heating, the hot water storage temperature in the hot water storage tank is raised to the required set temperature.

  The high-temperature and high-pressure liquid refrigerant radiated by the condenser 7a and condensed and liquefied is decompressed by the first expansion valve 8 and controlled to a predetermined flow rate, and then separated into gas and liquid by the gas-liquid separator 9. The separated liquid is further depressurized by the second expansion valve 10 and controlled to a predetermined flow rate, and then flows into the air heat exchanger 11 where it evaporates and absorbs heat from the outside air to be vaporized. The gas refrigerant thus vaporized is guided to the suction port side 2b of the first compressor 2 by the first four-way valve 12, and is sucked into the first compressor 2 and compressed again, and further the second compression. Compressed by the machine 3 and compressed in two stages.

  On the other hand, the gas phase component separated by the gas-liquid separator 9 sequentially passes through the injection pipe 18, the first and second four-way valves 12, 6, the opened three-way valve 5 and the connecting pipe 4, and then the suction port side 3b. Are sucked into the second compressor 3 and compressed again.

  Therefore, according to this two-stage heating operation, two-stage compression is performed by the first and second two compressors 2 and 3, so that the high-temperature and high-pressure gas discharged from the second compressor 3 on the higher stage side. The pressure and temperature of the refrigerant can be increased as compared with the single-stage compression. For this reason, since the condensation latent heat in the condenser 7a of the water heat exchanger 7 can be increased, the hot water boiling capacity of the water heat exchanger 7 can be increased. As a result, it is possible to increase the temperature of the tapping water and shorten the time for boiling up to the required temperature.

[Single stage heating operation]
FIG. 2 is a refrigeration cycle diagram at the time of single-stage heating operation by the hot water supply apparatus 1 according to the first embodiment shown in FIG. In this single stage heating, one of the first and second compressors 2 and 3 in the two stage heating operation shown in FIG. 1, for example, the compression operation of the first compressor 2 on the lower stage side is stopped (OFF), This is an operation method in which single-stage compression is performed only by the second compressor 3. In the drawings after FIG. 2, pipes indicated by broken lines in the drawings indicate non-passage channels through which the refrigerant does not flow, and broken line arrows indicate the refrigerant circulation direction during the defrosting operation.

  In this single-stage heating operation, for example, when the compression operation of the first compressor 2 on the lower stage side is stopped, the gas refrigerant outlet side of the air heat exchanger 11 is switched by the switching operation of the first four-way valve 12. Is connected to the suction port side 3b of the second compressor 3 on the higher stage side during the compression operation, and control is performed to bypass the refrigerant so as not to flow into the first compressor 2 during the compression operation stop. .

  That is, the controller 20 stops the compression operation of the first compressor 2 and switches the first four-way valve 12 to change the two-stage compression heating (compression) operation to a single-stage heating (compression) operation. Easy and fast switching. That is, even in the two-stage compression refrigeration cycle, the heating capacity can be suppressed (reduced) easily and quickly.

  FIG. 3 is a Mollier diagram A during the single-stage heating operation, and FIG. 4 is a Mollier diagram B during the two-stage heating operation. 3 and 4, broken lines indicate Mollier diagrams in the case where the heating capacity is suppressed by controlling the rotational speeds of the first and second compressors 2 and 3, respectively.

  That is, if the heating capacity is suppressed by controlling the rotational speeds of the first and second compressors 2 and 3, the refrigerant circulation flow rate circulating in the refrigeration cycle is reduced, so that the adiabatic efficiency is lowered.

  For this reason, the high pressure is decreased while the low pressure is increased. As a result, the compression ratio decreases.

  That is, as shown in FIGS. 3 and 4, if the condensing pressure P1 and the evaporation pressure P2 in the single stage heating operation A and the two stage heating operation B are the same pressure, respectively, one compressor in the two stage heating operation B The compression ratio applied is smaller than the compression ratio applied to one compressor A during single-stage heating operation.

  Therefore, if the heating capacity by the rotational speed control is suppressed during these two operations, the compression ratio necessary for one compressor cannot be ensured during the two-stage heating operation B. For this reason, the single-stage heating operation is more preferable in the operation in which the heating capacity is suppressed.

[Single-stage defrosting operation]
FIG. 5 is a refrigeration cycle diagram during the single-stage defrosting operation by the hot water supply apparatus 1 according to the first embodiment shown in FIG. In this single-stage defrosting operation, the compression operation of the first compressor 2 is stopped (OFF), the second four-way valve 6 is switched to the defrosting operation, and the first compressor 2 that has stopped the compression operation is refrigerated. Is switched by the first four-way valve 12 so as to be bypassed.

  As a result, the high-temperature and high-pressure gas refrigerant discharged from the second compressor 3 on the higher stage side is guided by the second and first four-way valves 6 and 12 and flows into the air heat exchanger 11, where The frost formation of the air heat exchanger 11 is heated and defrosted by the radiation of the latent heat of condensation of the gas refrigerant.

  The liquid refrigerant condensed and liquefied by the air heat exchanger 11 is decompressed by the second expansion valve 10 and adjusted to a required flow rate, and then flows into the gas-liquid separator 9 where it is separated into gas and liquid. .

  The liquid refrigerant is decompressed by the first expansion valve 8 and adjusted to a required flow rate, and then flows into the condenser 7a of the water heat exchanger 7, where it evaporates and passes through the water passage 7b. It absorbs heat from the feed water or hot water, and is sequentially guided by the second four-way valve 6, the opened three-way valve 5, and the connecting pipe 4 as a gas refrigerant, and is sucked into the second compressor 3 from the suction port side 3 b. It is compressed by the second compressor 3. At this time, the first compressor 2 whose operation is stopped is disconnected from the refrigerant circulation path.

[Second Embodiment]
(3-stage heating operation)
FIG. 6 is a refrigeration cycle diagram when a three-stage heating operation is performed by the first to third compressors 2, 3, and 21 by the hot water supply apparatus 1 </ b> A according to the second embodiment.

  This hot water supply apparatus 1A includes a third compressor 21, a second connection pipe 22, a second three-way valve 23, a discharge side pipe 24, a third hot water supply apparatus 1 according to the first embodiment shown in FIG. The four-way valve 25, the third expansion valve 26, the second gas-liquid separator 27, and the second injection pipe 28 are newly provided, and the first, second, and third three compressors 2, 3, 21 is characterized in that it is configured to be capable of three-stage heating operation, and the other configuration is the same as that of the hot water supply apparatus 1 shown in FIG.

  When the heating operation is performed by the first, second, and third three compressors 2, 3, and 21 by the hot water supply device 1 </ b> A configured as described above, the controller 20 has the first, second, and third units. The four-way valves 12, 6, 25 are switched to the heating operation side.

  Thus, the high-temperature and high-pressure gas refrigerant compressed in three stages by the first to third compressors 2, 3, 21 is discharged from the discharge side 21 a of the third compressor 21 on the high stage side to the discharge side pipe 24. And flows into the third four-way valve 25, where it is guided to the condenser 7 a of the water heat exchanger 7.

  In the condenser 7a, the high-temperature and high-pressure gaseous refrigerant condenses and liquefies, and the condensed latent heat heats the water flow in the water flow path 7b to bring it to hot water.

  The liquid refrigerant liquefied by the condenser 7a is then depressurized to a predetermined pressure by the first expansion valve 8 and adjusted to a predetermined flow rate, and then flows into the first gas-liquid separator 9, where It is separated into gas and liquid.

  The liquid component is further controlled to a predetermined pressure and flow rate by the third expansion valve 26 and then flows into the second gas-liquid separator 27, where it is separated into gas and liquid again.

  The liquid component separated here is further controlled to a predetermined pressure and flow rate by the second expansion valve 10 and then flows into the air heat exchanger 11. Here, the liquid refrigerant is vaporized by absorbing heat from the outside air due to the latent heat of evaporation. The gas refrigerant thus vaporized is sequentially guided by the second four-way valve 6 and the first four-way valve 12 and is sucked into the first compressor 2 from the suction port side 2b.

  The suction gas refrigerant is compressed at a predetermined compression ratio by the first compressor 2, passes through the open three-way valve 5 and the connecting pipe 4, and again at the predetermined compression ratio by the second compressor 3. Compressed.

  The high-temperature and high-pressure gas refrigerant compressed in two stages in this way further flows into the third compressor 21 through the second three-way valve 23 and the second connecting pipe 22 that are being opened. Compressed at the compression ratio. That is, three-stage compression is performed.

  The high-temperature and high-pressure gas refrigerant thus compressed in three stages is again discharged to the water heat exchanger 7 side. Thereafter, the above operation is repeated, and the water flow in the water flow path 7b of the water heat exchanger 7 is heated and boiled up to hot water of a predetermined temperature.

  Therefore, according to this hot water supply apparatus 1A, since the three-stage heating operation is performed by the three-stage compression by the first to third compressors 2, 3 and 21, the hot water is more than the two-stage heating operation shown in FIG. The boiling capacity can be further increased. For this reason, it is possible to increase the temperature of the hot water and improve the speed of boiling.

[Single stage heating operation]
FIG. 7 is a refrigeration cycle diagram during single-stage heating operation by the hot water supply apparatus 1A according to the second embodiment shown in FIG.

  The single stage heating operation by the hot water supply apparatus 1A stops (OFF) the compression operation of the first and second compressors 2 and 3 among the first to third compressors 2 and 3 and 21. This is an operation method in which the heating operation is performed by a single stage of only the third compressor 21 on the high stage side.

  In this single-stage heating operation, the third four-way valve 25 is switched to the heating operation side under the control of the controller 20, and the first and second four-way valves 12 and 6 are the first and first ones in which the compression operation is stopped. The two compressors 2 and 3 are switched so as to be disconnected from the refrigerant circulation passage of the refrigeration cycle.

  For this reason, as shown by the broken lines in FIG. 7, the first and second injection pipes 18 and 28 are non-passing pipes that do not allow the refrigerant to flow, and the first and second gas-liquid separators 9 and 27 The gas refrigerant for the gas phase separated from the liquid is prevented from flowing into the first and second compressors 2 and 3 during the stop of the compression operation.

  The gas refrigerant vaporized by the air heat exchanger 11 also bypasses (bypasses) the first and second compressors 2 and 3 by switching the refrigerant flow paths by the first and second four-way valves 12 and 6. Returning to the operating third compressor 21 only.

  Therefore, according to this hot water supply apparatus 1A, from the operation of three of the first to third compressors 2, 3 and 21, two compressors, for example, the operation of 2, 3 are stopped, and only one unit is stopped. By operating, it is possible to easily perform the heating capacity suppressing operation from the three multi-stage heating operation to the single-stage heating operation. Thereby, the operation range can be expanded.

  In addition, since this heating capacity suppression operation does not perform the rotational speed control of the first to third compressors 2, 3, and 21, it is possible to suppress a decrease in operating efficiency.

[Third Embodiment]
(First single-stage defrosting operation)
FIG. 8 is a refrigeration cycle diagram during the first single-stage defrosting operation by the hot water supply apparatus 1 according to the first embodiment shown in FIG. 1.

  The single-stage defrosting operation by the hot water supply device 1 stops (OFF) the compression operation of one of the first and second compressors 2 and 3, for example, the first compressor 2 on the lower stage side. In this method, only the second compressor 3 on the higher stage side is defrosted by a single stage.

  In the first single-stage defrosting operation, the first and second four-way valves 12 and 6 are switched to the defrosting operation side under the control of the controller 20, and the compression operation of the first compressor 2 is stopped. To switch to winding heating operation. Thereby, although the compression operation of the first compressor 2 is stopped, the first compressor 2 is operated by winding heating. Therefore, the first compressor 2 is not separated from the refrigerant circulation passage of the refrigeration cycle. Forming part.

  In the winding heating operation, electricity that does not generate a rotating magnetic field is applied to the windings of the first compressor 2, and only the windings are energized and heated without rotating the rotor. For this reason, the first compressor 2 is not compressed, but can be heated by winding heating when the refrigerant passes through the sealed container of the casing.

  Therefore, the high-temperature and high-pressure gas refrigerant that has been compressed by the second compressor 3 on the higher stage side and discharged from the discharge port 3a passes through the refrigerant pipe 13 and the second and first four-way valves 6 and 12. Are sequentially guided to flow into the air heat exchanger 11, where they are condensed and liquefied, and the frost is heated and defrosted by the radiation of the condensed latent heat.

  The liquid refrigerant condensed and liquefied by the air heat exchanger 11 is depressurized by the second expansion valve 10 and then separated into gas and liquid by the gas-liquid separator 9. The gaseous refrigerant separated here passes through the injection pipe 18 and is guided by the first four-way valve 12 to stop the compression operation and in the first compressor 2 during the winding heating operation. And is sucked into the second compressor 3 after being heated.

  Accordingly, since the gaseous refrigerant immediately before being sucked into the second compressor 3 during operation is heated by the first compressor 2 during the winding heating operation, the temperature of the suction gas refrigerant can be increased. As a result, since the temperature and pressure of the refrigerant discharged from the second compressor 3 can be increased, the latent heat of condensation in the air heat exchanger 11 can be increased. For this reason, the defrosting capability can be increased, and the defrosting time can be shortened accordingly.

  Moreover, since the liquid component can be vaporized by heating the suction gas of the 2nd compressor 3, the damage of the 2nd compressor 3 by a liquid back can be prevented beforehand.

  FIG. 12 is a Mollier diagram at the time of single-stage defrosting operation according to the third embodiment. In FIG. 12, point c2-d2 indicates adiabatic compression of the second compressor 3, d2-i2 indicates condensation in the air heat exchanger 11, i2-f2 indicates pressure reduction of the first expansion valve 8, and f2 -G2, j2 indicate the gas-liquid separation in the gas-liquid separator 9, and j2-c2 indicates the process of circulating to the first compressor 2 after being heated by the winding heating of the first compressor 2. Yes.

(Second single-stage defrosting operation)
FIG. 9 is a refrigeration cycle diagram in the second single-stage defrosting operation by the hot water supply apparatus 1 according to the first embodiment shown in FIG.

  The main feature of the second single-stage defrosting operation is that the amount of heat of hot water flowing through the water passage 7b of the water heat exchanger 7 with respect to the first single-stage defrosting operation shown in FIG. Is used for defrosting the air heat exchanger 11. Other than this, since it is the same as the first single-stage defrosting operation, the redundant description is omitted.

  That is, the controller 20 controls the opening degree of the first expansion valve 8 to circulate the liquid refrigerant separated by the gas-liquid separator 9 to the condenser 7a of the water heat exchanger 7 (point of FIG. 13). g3-e3).

  FIG. 13 is a Mollier diagram at the time of the second single-stage defrosting operation. In FIG. 13, points c3-d3 indicate single-stage compression of the first compressor 2, and d3-i3 indicates air. Condensation in the heat exchanger 11, i3-f3 is depressurization by the first expansion valve 8, g3-e3 is depressurization by the second expansion valve 10, and e3-c3 is a process of evaporation in the water heat exchanger 7. Respectively.

  According to the second single-stage defrosting operation, the liquid refrigerant in the condenser 7a acting as an evaporator absorbs heat from the water (hot water) in the water passage 7b of the water heat exchanger 7, so that the tapping temperature is correspondingly increased. Although it decreases, the amount of heat generated by the second compressor 3 can supplement the amount of heat that is insufficient for defrosting. As a result, the defrosting capacity can be increased, and the defrosting time can be shortened accordingly, so that the efficiency of the hot water supply operation can be improved accordingly.

  Further, the refrigerant for the gas separated by the gas-liquid separator 9 can be injected into the second compressor 3 through the injection pipe 18, the first compressor 2, the three-way valve 5 being opened, and the connecting pipe 4. . Thereby, since the refrigerant | coolant circulation flow rate of a refrigerating cycle can be aimed at, the increase in defrosting capability can be aimed at further.

[Fourth Embodiment]
(Single stage heating operation)
FIG. 10 is a refrigeration cycle diagram when the three-stage heating operation by the hot water supply apparatus 1A shown in FIG. 6 is replaced with a single-stage heating operation.

  That is, in the three-stage heating operation shown in FIG. 6, the first to third compressors 2, 3, and 21 perform the heating operation. In the single-stage heating operation according to the fourth embodiment, Among the first to third compressors 2, 3 and 21, the compression operation of the first and second compressors 2 and 3 is stopped (OFF), while the winding heating operation is performed. The main feature is that the heating operation is performed in a single stage using only the third compressor 21 on the high stage side.

  Even in this single-stage heating operation, two of the first to third compressors 2, 3, and 21 are stopped, so that the heating capacity suppression operation can be performed easily and efficiently. it can.

  In addition, since the first and second compressors 2 and 3 that have stopped the compression operation are wound and heated, the suction gas immediately before being sucked into the third compressor 21 on the high stage side during the compression operation. Can be increased by heating the windings of the first and second compressors 2 and 3.

  For this reason, since the temperature and pressure of the discharge gas discharged from the third compressor 21 can be increased, the efficiency of the heating operation can be improved.

[Single-stage defrosting operation]
FIG. 11 is a refrigeration cycle diagram when the single-stage heating operation of the water heater 1A shown in FIG. 10 is replaced with a single-stage defrosting operation.

  That is, this single-stage defrosting operation is performed only by the third compressor 21 by switching the first to third four-way valves 12, 6, and 25 from the heating operation to the defrosting operation by the controller 20. In the defrosting operation.

  And about the 1st, 2nd compressors 2 and 3 which stopped compression operation, since winding heating operation is carried out, the suction gas just before suck | inhaled by the 3rd compressor 21 is this 1st, 2nd Heating can be performed by heating the windings of the compressors 2 and 3. Thereby, the efficiency improvement of a defrost operation can be aimed at as mentioned above.

  In the above embodiment, two and three compressors have been described. However, the present invention is not limited to this, and four or more compressors may be provided.

  Further, the number of the first, second, and third compressors 2, 3, and 21 that are stopped during the heating operation and the defrosting operation and the number that performs the winding heating operation are not limited to the above embodiment.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of this invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the present invention. These embodiments and modifications thereof are included in the scope and gist of the present invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,1A ... Hot-water supply apparatus, 2 ... 1st compressor, 3 ... 2nd compressor, 6 ... 2nd four-way valve, 7 ... Hydrothermal exchanger, 7a ... Condenser, 8 ... 1st expansion valve DESCRIPTION OF SYMBOLS 10 ... 2nd expansion valve, 11 ... Air heat exchanger, 12 ... 1st four-way valve (switching means), 13 ... Refrigerant piping, 18 ... Injection pipe, 20 ... Controller, 21 ... 3rd compressor 25 ... a third four-way valve, 26 ... a third expansion valve, 27 ... a second gas-liquid separator.

Claims (5)

Multiple compressors connected in series for multi-stage compression, four-way valve, water heat exchanger, expansion means, and air heat exchanger, which are switched to heating operation or defrosting operation by switching the circulation direction of refrigerant, sequentially through refrigerant piping A refrigeration cycle that forms a refrigerant flow path for connecting and circulating the refrigerant;
When the compression operation of a part of the plurality of compressors is stopped, the refrigerant returning to the suction port side of the compressor is bypassed by the compressor during the compression operation stop, and the suction of the compressor during the compression operation is performed Switching means for switching a part of the refrigerant flow path so as to return to the mouth side;
The hot water supply apparatus characterized by comprising. The refrigeration cycle includes a gas-liquid separator that separates the gas-liquid refrigerant, and a refrigerant flow path that returns the gaseous refrigerant separated by the gas-liquid separator to the suction port side of the compressor,
In the defrosting operation, the switching means bypasses the refrigerant flow so that the gaseous refrigerant from the gas-liquid separator bypasses the water heat exchanger and returns to the suction port side of the compressor during the compression operation. The hot water supply apparatus according to claim 1, wherein a part of the path is switched. The hot water supply apparatus according to claim 1 or 2, wherein the refrigeration cycle is configured to be capable of defrosting operation by a single-stage compressor by switching operation of the switching means and the four-way valve. During the defrosting operation, the compressor that has stopped the compression operation is subjected to winding heating operation, and the switching unit is operating the refrigerant from the air heat exchanger via the compressor during the winding heating operation. The hot water supply apparatus according to claim 3, wherein a part of the refrigerant flow path is switched so as to return to the suction port side of the compressor. During the defrosting operation, the switching means switches a part of the refrigerant flow path so as to return the liquid refrigerant from the gas-liquid separator through the water heat exchanger to the suction port side of the compressor. The hot water supply apparatus according to claim 4, wherein the hot water supply apparatus is configured.

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