JP5574638B2 - Refrigeration air conditioner - Google Patents

Description

  The present invention relates to a refrigeration air conditioner that connects a heat source side unit and a load side unit, and after renewing the heat source side unit and the load side unit without replacing existing refrigerant pipes, The present invention relates to a refrigeration air conditioner capable of cleaning refrigerant piping.

  In the conventional refrigeration and air-conditioning apparatus, a heat exchanger is installed to connect the heat source side unit and the load side unit by providing a refrigerant heat exchanger that exchanges heat between the refrigerant in the gas pipe and the liquid pipe to bring the refrigerant into a gas-liquid two-phase state. After the unit was newly updated without replacing the refrigerant pipe, the existing refrigerant pipe was washed while performing the cooling / heating operation (for example, see Patent Document 1).

Japanese Unexamined Patent Publication No. 2007-064558 (FIG. 1)

  However, in the refrigerating and air-conditioning apparatus described in Patent Document 1, when the pipes are washed while performing heating operation (hereinafter referred to as heating washing), heat exchange is performed between the total flow rates of the gas pipe and the liquid pipe by the refrigerant heat exchanger. Therefore, the dryness at the gas pipe side outlet of the refrigerant heat exchanger may be unnecessarily lowered. As a result, the amount of liquid refrigerant in the gas pipe increases, resulting in a state of refrigerant shortage, the flow rate of refrigerant circulating in the refrigerant circuit is reduced, and pipe cleaning may take time.

  The present invention has been made to solve the above-described problems, and in particular, a refrigerating and air-conditioning system capable of quickly ending the cleaning operation by optimizing the dryness of the refrigerant in the gas pipe during heating cleaning. Device.

In the refrigeration air conditioner according to the present invention, a compressor, a four-way valve, a heat source side heat exchanger, a heat source side unit provided with a refrigerant heat exchanger, a throttling device, a load side unit provided with a load side heat exchanger, A first refrigerant pipe connecting the expansion device and the heat source side heat exchanger, a second refrigerant pipe connecting the four-way valve and the load side heat exchanger, and the first refrigerant pipe, the load side heat exchanger A first check valve that causes the refrigerant to flow from the side to the heat source side heat exchanger side, and a side that is not connected to the second refrigerant pipe in the flow path of the refrigerant heat exchanger. A refrigerant branch pipe that bypasses the valve, and is connected to the downstream side of the refrigerant heat exchanger in the refrigerant branch pipe in the refrigerant flow direction during cooling operation, and the refrigerant is supplied from the refrigerant heat exchanger side to the first refrigerant pipe side. a second check valve to flow, and an accumulator to the inlet side pipe of the compressor, the refrigerant heat Comprising a bypass pipe for passing a second of the first refrigerant in the refrigerant in the pipe that exchanges heat with the refrigerant of the refrigerant in the pipe to the accumulator inlet-side pipe by exchanger, a cooling operation, the refrigerant heat exchanger, a first The refrigerant flowing through the first refrigerant pipe and the refrigerant flowing through the second refrigerant pipe are heat-exchanged to supercool the refrigerant flowing through the first refrigerant pipe, and are discharged from the compressor by the refrigerant heat exchanger during heating operation. The gas refrigerant thus obtained is heat-exchanged with a part of the refrigerant in the first refrigerant pipe so as to be in a gas-liquid two-phase state, and flows into the second refrigerant pipe to clean the refrigerant pipe.

  According to the present invention, by optimizing the flow rate of the refrigerant flowing through the refrigerant heat exchanger and optimizing the dryness of the refrigerant in the gas refrigerant pipe, the amount of liquid refrigerant in the gas pipe increases and the refrigerant It is possible to obtain a refrigeration air-conditioning apparatus that can quickly finish heating washing without reducing the circulating flow rate in the circuit.

It is a refrigerant circuit figure which shows the refrigerating air conditioning apparatus which concerns on Embodiment 1 of this invention. It is an operation | movement flowchart which concerns on Embodiment 1 of this invention. It is a Mollier diagram which shows the refrigerating cycle in washing | cleaning which concerns on Embodiment 1 of this invention.

Embodiment 1 FIG.
FIG. 1 shows a refrigerating and air-conditioning apparatus according to the present embodiment.
In FIG. 1, a refrigeration air conditioner 1 includes a heat source side unit 2 and a load side unit 3 connected by a refrigerant pipe to form a refrigerant circuit. When the refrigerating and air-conditioning apparatus 1 is updated, only the heat source side unit 2 and the load side unit 3 are newly updated, and the existing refrigerant pipe is reused as the refrigerant pipe between both units. This Embodiment demonstrates the refrigerating air conditioning apparatus 1 after the refrigerating air conditioning apparatus 1 updated.

  The heat source side unit 2 includes an accumulator 6, a compressor 7, an oil separator 8, an oil tank 9 including a mineral oil recovery device 90, a check valve 10, a four-way valve 11, and a heat source side heat exchanger 12. Are sequentially connected by piping. The load side unit 3 is configured by sequentially connecting a load side heat exchanger 16 and an expansion device 15. The gas refrigerant pipe 4 is connected to the load side heat exchanger 16 via the refrigerant heat exchanger 17 from the four-way valve 11. In addition, the liquid refrigerant pipe 5 is connected to the heat source side heat exchanger 12 from the expansion device 15 via the pressure adjustment valve 14 and the check valve 13 in the heat source side unit 2.

  The refrigerant heat exchanger 17 is provided such that heat is exchanged between the refrigerant branch pipe 170 branched from the outlet side pipe of the check valve 13 and returning to the inlet side pipe and the refrigerant flowing in the gas refrigerant pipe 4. Further, a check valve 18 is provided in the refrigerant branch pipe 170 connected to the refrigerant heat exchanger 17 and the inlet side of the check valve 13, and is branched from the inlet side pipe of the check valve 18. A bypass pipe 171 connected to the inlet-side pipe of the accumulator 6 is provided through an electromagnetic valve 19 that allows the refrigerant to pass through at a given opening and blocks the others. In addition, although the refrigerant | coolant heat exchanger 17 has an effect which can be reduced in size when a plate-type heat exchanger or a double pipe heat exchanger is used, other heat exchangers may be used.

  Here, the electromagnetic valve 19 may be, for example, an electromagnetic valve having a fixed opening degree determined by a test or the like at the time of manufacturing the apparatus, or based on the state of the refrigerant in the gas refrigerant pipe 4. An electromagnetic valve that can adjust the degree of opening and closing may be used. Moreover, you may comprise as a refrigerant | coolant interruption | blocking means which interrupts | blocks the flow of a refrigerant | coolant by removing piping after piping washing | cleaning.

Next, after the refrigerating and air-conditioning apparatus 1 is updated, the operation until the normal air-conditioning operation is started will be described using the flowchart of FIG.
After the refrigerating and air-conditioning apparatus 1 is updated, the air-conditioning operation is started while the pipe is washed by an operation start switch (not shown) provided in the heat source side unit 2 or the load side unit 3. (Step 1)

  Next, it is selected whether the cooling operation or the heating operation is performed, and the operation mode is determined. (Step 2) In determining the operation mode, the indoor air temperature, the outdoor air temperature, or the like may be detected and automatically determined based on those values, or may be determined manually by the user.

  When the operation mode is determined, the compressor 7 is started, and piping cleaning is started together with the air conditioning operation. (Step 3) First, the operation in the case where pipe cleaning is performed during cooling operation (cooling cleaning) will be described. When the compressor 7 is started, the high-temperature and high-pressure gas refrigerant discharged from the compressor 7 is discharged and enters the oil separator 8. The refrigerating machine oil taken out from the compressor 7 together with the gas refrigerant is separated by the oil separator 8, flows through a pipe 172 connecting the lower part of the oil separator 8 and the oil tank 9, enters the oil tank 9, and returns to the oil return capillary 21. To return to the compressor 7. Here, since the oil of the gas refrigerant is separated from the gas refrigerant by the oil separator 8 and the oil tank 9, respectively, the separation efficiency can be increased. Moreover, adjusting the volume of the oil tank 9 has an effect of suppressing pressure pulsation of the refrigerant. On the other hand, the gas refrigerant flows to the heat source side heat exchanger 12 via the four-way valve 11 and is condensed and liquefied. The refrigerant condensed in the heat source side heat exchanger 12 flows into the refrigerant heat exchanger 17 through the liquid refrigerant pipe 5 and the refrigerant branch pipe 170, and further exchanges heat with the low-pressure gas-liquid two-phase refrigerant in the gas refrigerant pipe 4. Thus, a liquid refrigerant or a low-dryness gas-liquid two-phase refrigerant is obtained. At this time, the electromagnetic valve 19 is blocked so that the refrigerant does not flow into the bypass pipe 171, and the refrigerant returns to the liquid refrigerant pipe 5 via the check valve 18. This refrigerant is controlled to an intermediate pressure that is lower than the pressure resistance of the liquid refrigerant pipe 5 by the pressure adjusting valve 14 so that the detected value of the pressure sensor 50 does not exceed the allowable pressure of the liquid refrigerant pipe 5. Also, if the intermediate pressure detected by the pressure sensor 50 is likely to exceed the pressure resistance of the liquid refrigerant pipe 5, the operation of the refrigeration air conditioner 1 is stopped.

  With this configuration, even when the unit is updated with a refrigerant having different operating pressures such as R22 and R410A or R407C to R410A, the operation is performed so as not to exceed the pressure resistance of the liquid refrigerant pipe 5 and the gas refrigerant pipe 4. It can be controlled and is safe.

  The liquid or gas-liquid two-phase refrigerant controlled to the intermediate pressure enters the load side unit 3 and is further throttled to a low pressure by the throttle device 15. The liquid or gas-liquid two-phase refrigerant that has been squeezed to a low pressure flows into the load-side heat exchanger 16 and is evaporated and vaporized to cool the room to be air-conditioned. The evaporated and vaporized refrigerant becomes a gas-liquid two-phase refrigerant with high dryness and flows into the refrigerant heat exchanger 17. The refrigerant further evaporates and vaporizes to become a gas refrigerant, and enters the accumulator 6 through the four-way valve 11 together with liquid contaminants such as refrigeration oil that is compatible with the working refrigerant before the unit replacement remaining in the refrigerant pipe. . In the accumulator 6, the refrigerant gas and the contamination are separated, the refrigerant gas returns to the compressor 7, and the contamination stays in the accumulator 6. Contamination collected in the accumulator 6 is provided in the oil tank 9 from the bottom of the accumulator 6, and flows and stored in a mineral oil collector 90 in a space different from the oil tank 9. Here, it connects from the upper part of the mineral oil collection | recovery apparatus 90 to the inlet piping of the accumulator 6 from which the static pressure fell rather than the internal pressure of the accumulator 6 with the flow of the refrigerant | coolant. Thereby, the internal pressure of the mineral oil collector 90 can be made lower than the internal pressure of the accumulator 6, and the movement of contamination from the accumulator 6 to the mineral oil collector 90 can be promoted.

  Next, in step 3, the operation during the heating cleaning operation will be described. When the compressor 7 is started, the high-temperature and high-pressure gas refrigerant discharged from the compressor 7 is discharged and enters the oil separator 8. The refrigerating machine oil taken out from the compressor 7 together with the gas refrigerant is separated by the oil separator 8, flows through a pipe 172 connecting the lower part of the oil separator 8 and the oil tank 9, enters the oil tank 9, and connects the oil return capillary 21. To the compressor 7. On the other hand, the gas refrigerant flows into the refrigerant heat exchanger 17 through the four-way valve 11, exchanges heat with the low-temperature and low-pressure gas-liquid two-phase refrigerant in the refrigerant branch pipe 170, is condensed and liquefied, and has a high dryness. It becomes a two-phase refrigerant. Here, the bypass flow rate is adjusted to a predetermined value by adjusting the amount of the liquid refrigerant flowing to the bypass piping 171 side in advance by the size of the electromagnetic valve 19 at the outlet of the refrigerant heat exchanger 17. As a result, the heat exchange amount in the refrigerant heat exchanger 17 can be a heat exchange amount corresponding to the bypass flow rate, and further, the refrigerant heat exchanger 17 can be adjusted by adjusting the heat exchange amount to a predetermined value. It is also possible to adjust the dryness of the refrigerant at the outlet.

  The pressure of the refrigerant in the gas refrigerant pipe 4 is detected by the pressure sensor 40, and the capacity of the compressor 7 is controlled so that the detected value becomes constant. At this time, if the high pressure is likely to exceed the pressure resistance of the gas refrigerant pipe 4, the operation of the refrigeration air conditioner 1 is stopped by a pressure switch (not shown).

  With this configuration, even when the unit is updated with a refrigerant having different operating pressures such as R22 and R410A or R407C to R410A, the operation is performed so as not to exceed the pressure resistance of the liquid refrigerant pipe 5 and the gas refrigerant pipe 4. Can be controlled.

  The capacity control of the compressor 7 not only controls the frequency by driving the compressor 7 with an inverter, but also changes the number of compressors that are installed at a constant speed or sets a bypass valve (not shown). The capacity may be controlled by opening and closing.

  The gas-liquid two-phase refrigerant with high dryness enters the load side unit 3, flows through the gas refrigerant pipe 4, flows into the load side heat exchanger 16, is condensed and liquefied, and heats the room to be air-conditioned. The condensed and liquefied refrigerant is throttled to a low pressure by the throttle device 15 and the pressure regulating valve 14. The low-pressure gas-liquid two-phase refrigerant flows through the liquid refrigerant pipe 5 via the check valve 13 and is branched at the outlet pipe of the check valve 13, one at the refrigerant branch pipe 170 and the other at the other. It flows to the heat source side heat exchanger 12. The refrigerant that has flowed into the refrigerant branch pipe 170 enters the refrigerant heat exchanger 17 and exchanges heat with the high-temperature and high-pressure gas refrigerant in the gas refrigerant pipe 4 to evaporate and vaporize, so that the gas refrigerant or a highly dry gas-liquid two-phase refrigerant is obtained. It becomes. This refrigerant flows into the refrigerant circuit branched from the refrigerant branch pipe 170, flows through the bypass pipe 171 returning to the inlet side pipe of the accumulator 6 through the electromagnetic valve 19, and flows to the inlet side of the accumulator 6. At this time, the solenoid valve 19 has a fixed opening through which a predetermined amount of refrigerant flows, and the heat exchange amount of the refrigerant heat exchanger 17 is optimized. Further, since the refrigerant heat-exchanged by the refrigerant heat exchanger 17 has a lower pressure than the refrigerant in the liquid refrigerant pipe 5, the refrigerant hardly returns to the liquid refrigerant pipe 5.

  With this configuration, the dryness of the refrigerant in the gas refrigerant pipe 4 can be optimized, so that the amount of liquid refrigerant flowing in the gas refrigerant pipe 4 after heat exchange by the refrigerant heat exchanger 17 increases. As a result, the flow rate of the refrigerant in the refrigerant circuit does not decrease relatively, and the time required for the heating and cleaning is not shortened, so that the heating and cleaning can be completed quickly.

  As described above, the electromagnetic valve 19 is an electromagnetic valve whose opening degree can be adjusted, and detects the state of the refrigerant such as the dryness of the gas refrigerant pipe 4, and the opening degree is optimized so as to optimize the dryness. You may control so that it can adjust. As described above, the amount of heat exchange in the refrigerant heat exchanger 17 can be controlled by adjusting the flow rate of the refrigerant in the refrigerant branch pipe 170, so that the dryness of the refrigerant in the gas refrigerant pipe 4 can be optimized. The optimum dryness at this time may be 0.1 to 0.9, preferably about 0.8. In the case of dryness outside this condition, if it is close to liquid, the flow rate of the refrigerant will drop and the effect of removing foreign matter will be reduced, and if it is close to gas, there will be no liquid film flowing on the wall surface, and the central part of the pipe will be Since the sprayed liquid refrigerant only flows, foreign matter cannot be collected or floated in the liquid film, and the foreign matter cannot be collected, and the time for collecting the foreign matter becomes longer. It is important to operate in order to shorten the cleaning time.

  The refrigerant that has entered the heat source side heat exchanger 12 is evaporated and vaporized, flows through the four-way valve 11, merges with the refrigerant that flows in from the bypass pipe 171, and enters the accumulator 6. In the accumulator 6, the refrigerant gas and the contamination are separated, the refrigerant gas returns to the compressor 7, and the contamination stays in the accumulator 6. Contamination collected in the accumulator 6 is stored in the mineral oil collector 90 as appropriate after washing the pipe from a discharge port (not shown) provided at the bottom of the accumulator 6 as in the case of cooling washing.

  Here, when the gas refrigerant heat-exchanged by the refrigerant heat exchanger 17 or the gas-liquid two-phase refrigerant having a high dryness is returned to the liquid refrigerant pipe 5, the dryness of the refrigerant flowing through the heat source side heat exchanger 12 increases, and Since the flow rate of the refrigerant flowing through the heat source side heat exchanger 12 increases as compared with the case where the refrigerant flows through the inlet of the accumulator 6, the pressure loss in the liquid refrigerant pipe 5 is increased, and the low pressure on the suction side of the compressor 7 is increased. However, the refrigerant in the liquid refrigerant pipe 5 may exchange heat with the heat source side heat exchanger 12 by providing the bypass pipe 171 at the inlet of the accumulator 6 and flowing the refrigerant as in the present embodiment. Since it flows in a diverted manner to the vessel 17, such a problem does not occur.

  Furthermore, the operation | movement of the refrigerating cycle at the time of a heating washing operation is demonstrated using FIG. FIG. 3 is a Ph diagram illustrating the operation of the refrigeration cycle during heating and cleaning of the refrigeration air-conditioning apparatus of the present invention, where the horizontal axis indicates the specific enthalpy h, the vertical axis indicates the refrigerant pressure P, and T is Isotherm. In FIG. 3, the refrigerant in the state R2 compressed by the compressor 7 to a high temperature and high pressure flows into the refrigerant heat exchanger 17, and the low-pressure gas-liquid two-phase refrigerant (the refrigerant in the state R5 described later) in the refrigerant branch pipe 170. It is condensed by heat exchange and becomes a gas-liquid two-phase refrigerant with high dryness in the state R3. At this time, since the state R3 has an optimal dryness, the heat exchange amount of the refrigerant heat exchanger 17 is adjusted by setting the bypass refrigerant flow rate to a predetermined refrigerant flow rate. The refrigerant in the state R3 flows into the load side heat exchanger 16, condenses and liquefies, and becomes the state R4. The refrigerant in the state R4 is depressurized by the expansion device 15 and the pressure regulating valve 14, and becomes a gas-liquid two-phase state R5. A part of the refrigerant in the state R5 flows into the refrigerant branch pipe 170, exchanges heat with the high-temperature and high-pressure gas refrigerant in the gas refrigerant pipe 4 in the refrigerant heat exchanger 17, evaporates and vaporizes, flows into the bypass pipe 171 and flows into the accumulator 6 Return to the inlet piping. The other refrigerant in the state R5 flowing through the liquid refrigerant pipe 5 is evaporated and vaporized in the heat source side heat exchanger 12 to become the state R1, and is sucked into the compressor 1 again to complete the refrigeration cycle.

  In step 3, the air conditioning operation is performed for a predetermined time until the refrigeration cycle is stabilized in a steady state. The predetermined time is, for example, a case where the time change of high pressure or low pressure becomes a predetermined pressure or less in a state where the frequency of the compressor 7 reaches a predetermined frequency and becomes constant. Or it is good also as fixed time which calculated | required the time until it stabilizes by a test etc. and was decided beforehand. Thereby, the distribution state of the refrigerant in the refrigerating and air-conditioning apparatus 1 becomes appropriate, and a preparatory operation for accurately determining the refrigerant amount in the next step can be performed. Further, when the amount of refrigerant flowing in the pipe is extremely deviated from an appropriate amount and operation becomes difficult, the process proceeds to the next step.

  Next, the amount of refrigerant in the piping of the refrigeration air conditioner 1 is adjusted. (Step 4) First, the refrigerant is charged from the refrigerant charging port 20. When the supercooling degree (SC) at the condenser-side heat exchanger outlet of the refrigeration cycle or the superheat degree (SH) at the evaporator-side heat exchanger outlet is detected, the refrigerant is charged when a predetermined value is reached. finish. If the refrigerant amount does not reach an appropriate amount even after charging for a predetermined time or longer, the operation is stopped, and a warning of time over is issued to the outside by a notifying means (not shown).

  Here, the refrigerant amount is determined to be appropriate if it satisfies either the refrigerant amount necessary for normal air conditioning operation or the refrigerant amount necessary for continuing pipe cleaning. However, the amount of refrigerant required to continue pipe cleaning is satisfied, but if the amount of refrigerant required for normal air-conditioning operation is not satisfied, the refrigerant amount is adjusted again after completing a series of pipe cleaning operations. Report to the outside that it is necessary to implement.

  In addition, about refrigerant | coolant filling, when the discharge temperature of the compressor 7 overheats during washing | cleaning driving | operation, it fills suitably, and it may adjust a refrigerant | coolant amount anew after piping washing | cleaning.

  When the adjustment of the refrigerant amount is completed, the pipe cleaning is resumed. (Step 5) The same operation as step 3 is performed for a predetermined time. Here, the predetermined time is, for example, a parameter that increases or decreases the refrigerant flow rate during pipe cleaning due to the high or low pressure of the refrigeration cycle operation, such as outdoor air temperature or indoor air temperature, and the pipe length such as the pipe length. Parameters that affect the time required to move the residual oil are selected by testing and determined based on them. The pipe length may be determined from the difference between the evaporation temperature detected on the load side and the evaporation temperature detected on the heat source side, the opening of the throttle to be balanced, or the like.

  Next, the contaminants stored in the mineral oil recovery device 90 are appropriately discharged from the discharge port (not shown) after pipe cleaning. Further, after the pipe cleaning, the discharge port (not shown) provided at the bottom of the accumulator 6 is switched from the connection to the mineral oil recovery device 90 to the connection to the oil return circuit (not shown) to the compressor 7. (Step 6). Completion of the oil discharge may be confirmed by an operator visually, and a means (not shown) may be used to notify the heat source side unit 2 or the oil in the accumulator 6 may be detected with a liquid level detection sensor or the like. It may be detected automatically. Furthermore, when the completion of oil discharge is not confirmed for a predetermined time or more, the operation of the refrigeration air conditioner 1 may be stopped and an overtime warning may be issued to the outside.

  When discharge of contamination from the mineral oil recovery machine 90 is completed, normal air conditioning operation is started. (Step 7) At this time, the oil return solenoid valve 22 is opened, and the refrigerating machine oil in the oil tank 9 is returned to the compressor 7 together with the refrigerant gas via the suction side piping of the compressor 7.

  By adopting such a configuration, the oil taken out from the compressor 7 at the time of pipe cleaning can be quickly returned to the compressor 7 after the pipe cleaning, and the refrigeration oil in the compressor 7 can be obtained even after the pipe cleaning. A sufficient amount of oil can be ensured, and reliability can be increased without oil depletion. Moreover, the trouble of filling from the outside after washing can be saved.

  Next, an operation when performing a normal cooling operation will be described. When the compressor 7 is started, the high-temperature and high-pressure gas refrigerant and the refrigerating machine oil taken out from the compressor 7 are separated by the oil separator 8. The gas refrigerant is condensed and liquefied by the heat source side heat exchanger 12 through the four-way valve 11, separated by the oil separator 8, and flows through the pipe 172 connecting the lower part of the oil separator 8 and the oil tank 9 to the oil tank 9. The refrigerating machine oil flows to the suction pipe of the compressor 7 via the oil return capillary 21 and returns to the compressor 7 together with the refrigerant. The liquid refrigerant condensed and liquefied in the heat source side heat exchanger 12 is further condensed by exchanging heat with the low-pressure gas-liquid two-phase refrigerant in the refrigerant heat exchanger 17 to increase the degree of supercooling. This liquid refrigerant is throttled to an intermediate pressure by the pressure regulating valve 14.

  Here, the pressure regulating valve 14 is controlled so as to be lower than the pressure resistance of the liquid refrigerant pipe 5, and a sufficient degree of supercooling is provided so that the gas-liquid two-phase state does not occur even when the pressure is reduced to the intermediate pressure. The liquid single-phase refrigerant at the intermediate pressure flows through the liquid refrigerant pipe 5 and is throttled to a low pressure by the throttle device 15. In the unlikely event that the intermediate pressure exceeds the pressure resistance of the liquid refrigerant pipe 5, the pressure switch 64 is activated and the air conditioning operation is stopped.

  In the load-side heat exchanger 16, the low-pressure liquid refrigerant evaporates and vaporizes to cool the air-conditioning target space, and the refrigerant becomes a gas refrigerant and flows through the gas refrigerant pipe 4. The gas refrigerant that has flowed into the gas refrigerant pipe 4 merges with the gas-liquid two-phase refrigerant that is bypassed from the liquid refrigerant pipe 5 via the expansion device 23. Furthermore, the refrigerant heat exchanger 17 returns to the compressor 7 via the four-way valve 11 and the accumulator 6 in a state where it is vaporized by exchanging heat with the high-pressure liquid refrigerant.

  Next, the operation when performing a normal heating operation will be described. When the compressor 7 is driven, the high-temperature and high-pressure gas refrigerant and the refrigerating machine oil taken out from the compressor 7 are separated by the oil separator 8. The refrigerating machine oil separated by the oil separator 8 flows through the pipe 172 connecting the lower part of the oil separator 8 and the oil tank 9 to the oil tank 9, and then flows into the suction pipe of the compressor 7 through the oil return capillary 21. Return to the compressor 7 together with the refrigerant. The refrigerant gas is condensed and liquefied by the refrigerant heat exchanger 17 via the four-way valve 11, flows through the gas refrigerant pipe 4, and flows to the load side heat exchanger 16. Here, the high-pressure gas is controlled to a pressure that does not exceed the pressure resistance of the gas refrigerant pipe 4. In the unlikely event that the pressure resistance of the gas refrigerant pipe 4 is likely to be exceeded, the pressure switch 64 is activated to stop the operation. The high-dryness refrigerant is condensed and liquefied by the load-side heat exchanger 16 to heat the air-conditioning target space, and the refrigerant is throttled to a low pressure by the expansion device 15. The low-pressure gas-liquid two-phase refrigerant flows through the liquid refrigerant pipe 5, evaporates and vaporizes in the heat source side heat exchanger 12, and returns to the compressor 7 via the four-way valve 11 and the accumulator 6.

  As described above, the refrigerant in the gas-liquid two-phase state that enables the heating operation by condensing in the load-side heat exchanger 16 while flowing into the liquid refrigerant pipe 5 and the gas refrigerant pipe 4 at the start of the air-conditioning operation and performing the cleaning operation. The refrigerant flow rate of the refrigerant heat exchanger 17 is further adjusted so that the refrigerant flowing in the gas refrigerant pipe 4 does not have a higher dryness than necessary. That is, especially during the heating and washing operation, the refrigerant flow rate in the refrigerant branch pipe 170 can be adjusted to optimize the dryness of the refrigerant flowing in the gas refrigerant pipe 4, so that the refrigerant heat exchanger 17 can perform the entire operation as before. When heat exchange is performed between the flow rates, it may take time to clean the pipe. However, with this configuration, the pipe cleaning time does not decrease without reducing the flow rate of refrigerant flowing in the pipe on the refrigerant circuit. Will not be long.

  In addition, although the example which has one heat source side unit 2 was shown in a present Example, it cannot be overemphasized that the same effect is show | played also in the system with which two or more heat source side units 2 were connected. Needless to say, the same effect can be obtained even when there are a plurality of load-side units 3.

  DESCRIPTION OF SYMBOLS 1 Refrigeration air conditioner, 2 Heat source side unit, 3 Load side unit, 4 Gas refrigerant piping, 5 Liquid refrigerant piping, 6 Accumulator, 7 Compressor, 8 Oil separator, 9 Oil tank, 11 Four-way valve, 12 Heat source side heat exchange , 15 throttle device, 16 load side heat exchanger, 17 refrigerant heat exchanger, 18 check valve, 19 solenoid valve, 171 bypass piping.

Claims (4)

A heat source side unit including a compressor, a four-way valve, a heat source side heat exchanger, a refrigerant heat exchanger, and
A throttle unit, a load side unit equipped with a load side heat exchanger, and
A first refrigerant pipe connecting the expansion device and the heat source side heat exchanger;
A second refrigerant pipe connecting the four-way valve and the load side heat exchanger;
A first check valve that is connected to the first refrigerant pipe and causes the refrigerant to flow from the load side heat exchanger side to the heat source side heat exchanger side;
A refrigerant branch pipe connected to a side of the flow path of the refrigerant heat exchanger to which the second refrigerant pipe is not connected, and bypassing the first check valve;
A second reverse flow is connected to the downstream side of the refrigerant heat exchanger in the refrigerant branch pipe in the refrigerant flow direction during the cooling operation, and the refrigerant flows from the refrigerant heat exchanger side to the first refrigerant pipe side. A stop valve,
An accumulator on the inlet side pipe of the compressor;
A bypass pipe that flows the refrigerant in the first refrigerant pipe that has exchanged heat with the refrigerant in the second refrigerant pipe by the refrigerant heat exchanger to the inlet side pipe of the accumulator;
With
During the cooling operation, the refrigerant heat exchanger causes the refrigerant flowing through the first refrigerant pipe to pass through the heat exchange between the refrigerant flowing through the first refrigerant pipe and the refrigerant flowing through the second refrigerant pipe. Cool,
During the heating operation, the refrigerant heat exchanger makes the gas refrigerant discharged from the compressor heat-exchanged with a part of the refrigerant in the first refrigerant pipe to be in a gas-liquid two-phase state, and the second A refrigerant air-conditioning apparatus, wherein the refrigerant pipe is washed by flowing through the refrigerant pipe. The refrigerating and air-conditioning apparatus according to claim 1 , wherein an electromagnetic valve is provided in the bypass pipe. The refrigerating and air-conditioning apparatus according to claim 2 , wherein the opening degree of the electromagnetic valve can be adjusted according to a state of a refrigerant circuit. Dryness of the second state refrigerant of the refrigerant pipe into the sink gas-liquid two-phase to any one of claims 1-3, characterized in that 0.1 to 0.9 Refrigeration air conditioner of description.

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