JP4488712B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner that performs cooling and heating, and relates to a configuration and operation control of a refrigerant circuit device in which existing laid piping can be used as it is even when the refrigerant pressure is high.

  A conventional air conditioner generally includes an outdoor unit as a heat source unit, an indoor unit as a usage-side device, and a refrigerant pipe connecting them. The outdoor unit has a compressor and a heat source side heat exchanger, the indoor unit has a use side heat exchanger and a throttling device, and the above compressor, heat source side heat exchanger, throttling device, use side heat exchanger, etc. are connected by piping. Thus, a refrigeration cycle is configured. (For example, refer to Patent Document 1).

There are HCFC refrigerants such as R22 (fluorocarbons containing chlorine and hydrogen) as refrigerants filled in the refrigeration cycle. Recently, from the viewpoint of environmental protection, HFC refrigerants with zero ozone destruction coefficient (fluorocarbons containing no chlorine). For example, air conditioners using R407C refrigerant (mixed refrigerant of R32, R125, and R134a) and R410A refrigerant (mixed refrigerant of R32 at 50 wt% and R125 at 50 wt%) have appeared.
When a user replaces an air conditioner that uses an HCFC refrigerant with an air conditioner that uses an HFC refrigerant, the connection pipe of the air conditioner that has been used so far is used from the viewpoint of ease of construction and cost reduction of parts. It can be reused as it is as a transition pipe for a new air conditioner.

JP 2001-091023 A (page 2-4, FIG. 1)

  The conventional air conditioner is characterized in that the operating pressure of the R410A refrigerant among the HFC-based refrigerants is about 1.5 times higher than that of the R22 refrigerant and the R407C refrigerant. Therefore, the R410A refrigerant is used in the new air conditioner. When replacing with equipment, especially in models with a relatively large pipe diameter, the design pressure will exceed the pressure resistance standard value of the connection pipe to be reused, so the connection pipe must be changed to a thick wall, There was a problem that construction cost and piping cost became large.

  The present invention has been made to solve the above-described problems, and does not cause a problem of pressure resistance even if the pressure of the refrigerant to be used is high, and reuses the existing piping of the original air conditioner. It aims at providing the air conditioning apparatus which can do.

In the air conditioner according to the present invention, at least one indoor unit having a first compressor, an outdoor unit having a first heat exchanger, a first expansion device, and a second heat exchanger. A first refrigeration cycle having a first connection pipe and a second connection pipe connecting the indoor unit and the outdoor unit, a second compressor, and a third heat exchanger, A second refrigeration cycle in which a second expansion device, a fourth heat exchanger, and a sixth heat exchanger are connected by a refrigerant pipe, and the second refrigeration cycle in the first refrigeration cycle One connection pipe and the refrigerant pipe between the second expansion device and the sixth heat exchanger in the second refrigeration cycle can exchange heat with each other by the fourth heat exchanger. As described above, the second connection pipe in the first refrigeration cycle and the upper in the second refrigeration cycle The refrigerant pipes between the second compressor and the fourth heat exchanger are respectively configured to be able to exchange heat with each other in the sixth heat exchanger, and the first refrigeration During the defrosting operation of the cycle, the sixth heat exchanger heats the low-temperature two-phase refrigerant of the first refrigeration cycle with the high-temperature discharged refrigerant of the second refrigeration cycle .

In the present invention, since the efficiency of the air conditioner can be improved and the operating pressure of the refrigerant can be reduced by additionally connecting the second refrigeration cycle to the existing refrigerant pipe, the pressure of the refrigerant used is high. However, it is possible to obtain an air conditioner that does not cause a problem of pressure resistance of the refrigerant pipe and that can reuse the existing pipe of the original air conditioner.
Therefore, when replacing the air conditioner, it is possible to obtain an air conditioner with a low construction cost and a low total replacement cost.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus showing Embodiment 1 of the present invention.
In the figure, the compressor 1, the four-way switching valve 2, the first heat exchanger 3, the first ball valve 4a, the second ball valve 4b, the first expansion device 5, and the second The heat exchanger 6, the third ball valve 4c, and the fourth ball valve 4d are connected by a refrigerant pipe, and the outdoor unit A and the indoor unit B are surrounded by broken lines in the figure, respectively. Consists of parts and piping.
In particular, the first connection pipe 7 between the first ball valve 4a and the second ball valve 4b, and the second connection pipe 8 between the third ball valve 4c and the fourth ball valve 4d. If the existing pipes of the old air conditioner installed before the outdoor unit A and the indoor unit B are used as they are, or if new pipes are used when the outdoor unit A and the indoor unit B are installed Sometimes it is done.
In the indoor unit B, a plurality of first expansion devices 5 and second heat exchangers 6 may be installed in parallel.

The first blower 9 sends air to the first heat exchanger 3, and the second blower 10 sends air to the second heat exchanger 6.

The first heat pump refrigeration cycle 11 is configured by the pipe connection in the outdoor unit A and the indoor unit B.
The heat pump refrigeration cycle 11 is filled with a natural refrigerant such as carbon dioxide or the above-described HFC-based high-pressure refrigerant, for example, R410A refrigerant.

Next, the compressor 21, the four-way switching valve 22, the third heat exchanger 23, the second expansion device 24, and the fourth heat exchanger 25 are connected by a refrigerant pipe, and the second A heat pump refrigeration cycle 26 is configured. The second throttling device 24 can also use an inexpensive refrigerant flow rate control means such as a capillary tube or a precise flow rate control means using an electronic expansion valve.
In the fourth heat exchanger 25, heat exchange between the first connection pipe 7 of the first refrigeration cycle 11 and the refrigerant is performed.
The third blower 27 sends air into the third heat exchanger 23.

The first control device 28a controls the operation of the first compressor 1, the switching of the first four-way switching valve 2, the operation of the first blower 9 and the like of the first refrigeration cycle 11, and the like. The second control device 28b controls the operation of the second compressor 21 in the second refrigeration cycle 26, the switching of the second four-way switching valve 22, the operation of the second blower 27, etc. The control device 28 a and the second control device 28 b are connected via a communication line 29.

The heat pump refrigeration cycle 26 is filled with a natural refrigerant such as carbon dioxide or the above-described HFC-based high-pressure refrigerant, for example, R410A refrigerant.

Next, operation | movement of the refrigerating cycle of this air conditioning apparatus is demonstrated.
In the first refrigeration cycle 11, during the cooling operation and the dehumidifying operation, the refrigerant flows in the direction of the solid line in the figure, the first heat exchanger 3 functions as a condenser, and the second heat exchanger 6 functions as an evaporator. Further, during the heating operation, the four-way switching valve 2 is switched to cause the refrigerant to flow in the direction of the broken-line arrow in the figure, the second heat exchanger 6 is the condenser, and the first heat exchanger 3 is the evaporator. Function as.

In the second refrigeration cycle 26, during the cooling operation and the dehumidifying operation, the refrigerant flows in the direction of the solid line arrow in the figure, the third heat exchanger 23 is a condenser, and the fourth heat exchanger 25 is an evaporator. In the heating operation, the four-way switching valve 22 is switched, so that the refrigerant flows in the direction of the broken line arrow in the figure, the fourth heat exchanger 25 is the condenser, and the third heat exchanger 23 is Functions as an evaporator.

The switching control of the first four-way switching valve 2 and the switching control of the second four-way switching valve 22 are interlocked with each other. When the first refrigeration cycle 11 is in the cooling operation, the second refrigeration is performed. The cycle 26 is also controlled to be in the cooling operation. Similarly, the dehumidifying operation and the heating operation are linked and controlled so as to be in the same operation mode, but the defrosting operation has different frosting amounts on the evaporator side in each refrigeration cycle. At the same time, the operation is switched so as not to enter the defrosting operation, and when the defrosting is completed, the normal heating operation is resumed.
The first fan 3 of the first refrigeration cycle 11 and the second refrigeration cycle 26 and the second fan 27 are controlled in the same manner during both the cooling operation and the heating operation.

Here, during the cooling operation and the dehumidifying operation, the outlet side refrigerant from which the heat of condensation has been removed in the first heat exchanger 3 in the first refrigeration cycle 11 acts as an evaporator in the second refrigeration cycle 26. The heat is further exchanged by the fourth heat exchanger 25, and the degree of supercooling of the refrigerant is increased, and the condensation temperature and pressure of the first refrigeration cycle 11 are lowered, so that the low compression ratio operation is performed. Moreover, the heat exchange amount of an evaporator increases because the entrance dryness of the 2nd heat exchanger 6 becomes small. As a result, high-efficiency operation with high cooling capacity and low compressor input is possible.

In order to realize the above-described highly efficient operation with a low condensation pressure, the evaporation temperature in the fourth heat exchanger 25 of the second refrigeration cycle 26 may be equal to or lower than the condensation temperature of the first refrigeration cycle 11. The capacity of the second compressor 21 of the second refrigeration cycle 26 is sufficient to be smaller than that of the compressor 1 used in the first refrigeration cycle 11.
That is, the heat exchange capacities of the third heat exchanger 27 and the fourth heat exchanger 25 of the second refrigeration cycle 26 are the same as those before the pressure in the pipe during the operation of the first refrigeration cycle 11 is changed. The degree or maximum operating pressure is designed so as not to exceed the allowable pressure of the pipe, and the compressor capacity of the second refrigeration cycle 26 may be any capacity that can obtain the above heat exchange capacity. For example, it can be realized with a capacity of about 20 to 30% or less with respect to the capacity of the machine 1.

Next, during the heating operation, the refrigerant condensed in the second heat exchanger 6 in the first refrigeration cycle 11 is decompressed by the first expansion device 5 and then becomes a condenser in the second refrigeration cycle 26. Heat is exchanged by the fourth heat exchanger 25, and the temperature is raised. For this reason, since the evaporation temperature and pressure of the first refrigeration cycle 11 increase, the first compressor 1 of the first refrigeration cycle 11 becomes a low compression ratio operation, and as a result, a highly efficient operation is possible. Become.

In order to realize the above-described high-efficiency operation with a high evaporation pressure, the condensation temperature in the fourth heat exchanger 25 of the second refrigeration cycle 26 may be equal to or higher than the evaporation temperature of the first refrigeration cycle 11. The capacity of the second compressor 21 of the second refrigeration cycle 26 is sufficient to be smaller than that of the compressor 1 used in the first refrigeration cycle 11.

The equipment constituting the second refrigeration cycle 26 is installed so as to be added to the air conditioner constituting the first refrigeration cycle 11, and the first refrigeration cycle 11 and the second refrigeration cycle 26 are interlocked. Even when the first refrigeration cycle 11 is replaced with a high-pressure refrigerant device such as R410A by performing the operation control, the existing refrigerant pipes 7 and 8 do not increase the condensation pressure as compared with the air conditioner before the replacement. Therefore, it is possible to obtain an air conditioner that can reuse the existing pipe of the original air conditioner without causing the problem of refrigerant pipe pressure resistance.

  At the same time, since highly efficient operation can be realized in the cooling operation and the heating operation, it can be supplied as a device with high energy saving performance.

  In addition, if the equipment constituting the second refrigeration cycle 26 can be supplied at a lower cost than the construction cost for replacing the existing pipe with the high pressure-resistant pipe, or the running cost associated with the reduction in energy consumption due to high efficiency, the replacement cost will be increased. A total inexpensive air conditioner can be obtained.

Further, even when the air conditioner constituting the first refrigeration cycle 11 is not replaced with a high-pressure refrigerant device, by installing the equipment constituting the second refrigeration cycle 26 so as to be added, the existing air It is possible to improve the efficiency of the harmony device, that is, to save energy.

Embodiment 2. FIG.
FIG. 2 is a refrigerant circuit diagram of an air-conditioning apparatus showing Embodiment 2 of the present invention.
In the figure, the fourth heat exchanger 25 is provided in a pipe between the first heat exchanger 3 and the first ball valve 4a in the refrigerant circuit of the outdoor unit A. In the fourth heat exchanger 25, Then, heat exchange is performed between the first connection pipe 7 of the first refrigeration cycle 11 and the refrigerant.
That is, the equipment constituting the second refrigeration cycle 26 is added to the refrigerant pipe between the outdoor unit A and the indoor unit B in the first embodiment, whereas in this embodiment, the equipment is built in the outdoor unit A. Take composition.
Alternatively, if the equipment constituting the second refrigeration cycle 26 shares a part of the refrigerant circuit with the fourth heat exchanger 25, the outside of the structure constituting the outdoor unit A or the equipment may be applied. It may be installed in close proximity.

When replacing an air conditioner using an HCFC refrigerant with an air conditioner having a higher operating pressure than the former refrigerant, for example, an HFC R410A or an air conditioner in which carbon dioxide refrigerant is sealed, Replacing the outdoor unit A in the figure with a device incorporating the equipment constituting the second refrigeration cycle 26, the existing piping of the original air conditioner, that is, between the outdoor unit A and the indoor unit B It is possible to reuse the first connection pipe 8 and the second connection pipe 7 which are refrigerant pipes.
Further, the same effect can be obtained without replacing the indoor unit B.
Therefore, in addition to the effects described in the first embodiment, the installation work can be further simplified.

Embodiment 3 FIG.
FIG. 3 is a refrigerant circuit diagram of the air-conditioning apparatus showing Embodiment 2 of the present invention.
In the figure, the fifth heat exchanger 23a is installed close to the first heat exchanger 3, and the first blower 9 supplies air to the first heat exchanger 3 and the fifth heat exchanger 23a simultaneously. Send it in.
The first heat exchanger 3 and the fifth heat exchanger 23a do not share a heat transfer tube with each other, but if the heat exchanger is a plate fin tube, the fins may be shared with each other. Compared with the proximity installation, the heat exchange performance between the refrigerant pipes is further improved.

  By adopting the above-described configuration, the first heat exchanger 3 and the fifth heat exchanger 23a need only one blast power of the first blower 9, so that power recovery can be achieved. Efficiency improvement, that is, energy saving can be realized.

Embodiment 4 FIG.
FIG. 4 is a refrigerant circuit diagram of an air-conditioning apparatus showing Embodiment 4 of the present invention.
In the figure, a sixth heat exchanger 30 is connected between the second four-way switching valve 22 and the fourth heat exchanger 25 of the second refrigeration cycle 26. Heat exchange between the second connection pipe 8 of the refrigeration cycle 11 and the refrigerant.

During the heating operation, in the sixth heat exchanger 30, the high temperature discharge refrigerant from the first compressor 1 in the first refrigeration cycle 11 and the high temperature discharge from the second compressor 21 in the second refrigeration cycle 26. Heat exchange is performed between the refrigerants, but it does not affect operation.
On the other hand, during the defrosting operation for removing frost generated in the first heat exchanger 3 during the heating operation, the first refrigeration cycle 11 takes the same refrigerant circulation path as the cooling operation, and the second connection pipe 8 and A low temperature gas-liquid two-phase refrigerant flows through the sixth heat exchanger 30. The high-temperature discharge refrigerant from the second compressor 22 of the second refrigeration cycle 26 exchanges heat with the low-temperature two-phase refrigerant flowing through the sixth heat exchanger 30 of the first refrigeration cycle 11, and the low-temperature two-phase refrigerant Is evaporated by heating.

As a result, the pressure difference between the condensation pressure (high pressure) and the evaporation pressure (low pressure) of the first refrigeration cycle 11 is reduced, the refrigerant flow rate in the cycle is increased, and the third heat exchanger 3 is frosted. Since the defrosting capability is improved by increasing the heat exchange amount at the time and the defrosting operation time of the circuit is shortened, the room temperature decrease on the indoor unit B side during the defrosting operation can be reduced, Increases comfort.
Even if the first refrigeration cycle 11 performs a defrosting operation and the refrigerant flow is switched, the refrigerant flow is not switched in the second refrigerant cycle 26 and the operation is continued in the heating operation mode. Therefore, heat exchange with the low-temperature two-phase refrigerant flowing through the sixth heat exchanger 30 of the first refrigeration cycle 11 is possible as described above, and the defrosting operation of the first refrigeration cycle 11 is completed. The first refrigeration cycle 11 returns to the heating operation.

Next, FIG. 5 is a refrigerant circuit diagram of an air-conditioning apparatus showing Embodiment 4 of the present invention.
In the figure, a bypass pipe 31 branches from between the second four-way switching valve 22 and the sixth heat exchanger 30 of the second refrigeration cycle 26, and the fourth heat is passed through the first check valve 32. It is connected to the outlet pipe by an exchanger. A second check valve 33 is connected to the pipe between the connecting portion with the outlet pipe and the sixth heat exchanger 30.
During the heating operation of the second refrigeration cycle 26, the refrigerant flows through the sixth heat exchanger 30, and does not flow during the cooling operation.

Here, when the first refrigeration cycle 11 is in the defrosting operation, as described above, the high-temperature refrigerant in the second refrigeration cycle 26 flows through the sixth heat exchanger. Since the defrosting operation time of the circuit is shortened, the room temperature drop on the indoor unit B side during the defrosting operation can be reduced, and the comfort is increased.
On the other hand, when the first refrigeration cycle 11 is in the cooling operation, the refrigerant evaporated in the fourth heat exchanger 25 of the second refrigeration cycle 26 is not compressed through the sixth heat exchanger 30 and is compressed by the second compression. Since it returns to the machine 21, the refrigerant | coolant pressure loss at the time of passing through the 6th heat exchanger 30 is reduced.
As a result, the decrease in room temperature on the indoor unit B side during the defrosting operation can be reduced, the comfort is increased, the efficiency of the second refrigeration cycle 26 is improved during the cooling operation, and the operation of the entire system is extended. Efficiency is improved.

Embodiment 5 FIG.
FIG. 6 is a refrigerant circuit diagram of an air-conditioning apparatus showing Embodiment 5 of the present invention.
In the figure, a seventh heat exchanger 40 is connected between the second four-way switching valve 22 and the fourth heat exchanger 25 of the second refrigeration cycle 26. The refrigerant is exchanged with the outlet side piping of the accumulator 41 of the refrigeration cycle 11.
Further, the bypass pipe 31 branches from between the second four-way switching valve 22 and the seventh heat exchanger 40 of the second refrigeration cycle 26, and the fourth heat exchange is performed via the first check valve 32. Connected to the outlet piping. A second check valve 33 is connected to the pipe between the connection portion with the outlet pipe and the seventh heat exchanger 40.
During the heating operation of the second refrigeration cycle 26, the refrigerant flows through the seventh heat exchanger 40 and does not flow during the cooling operation.

Next, the operation of the refrigeration cycle will be described.
During the heating operation, the high-temperature discharge refrigerant of the second refrigeration cycle 26 heats the suction refrigerant in the outlet side piping of the accumulator 41 of the first refrigeration cycle 11 via the seventh heat exchanger 40. In particular, at the time of heating start-up, the refrigerant sucked in the first refrigeration cycle is often sucked into the compressor in a liquid state, and the refrigerant circulation amount is also small.
At the start of heating, the second refrigeration cycle 26 is activated simultaneously with the first refrigeration cycle 11 or activated at a predetermined time earlier, and when the second refrigeration cycle 26 is activated, the first refrigeration cycle 11 is activated. May be activated.
In this way, by heating the suction refrigerant, the refrigerant circulation amount of the first refrigeration cycle 11 is increased, and it is possible to compensate for the lack of capacity at the time of heating startup.
Moreover, by evaporating the liquid return-like refrigerant, damage to the compressor due to the liquid refrigerant can be prevented, and the reliability of the apparatus is improved.

  Further, during the defrosting operation, the refrigerant circulation amount of the first refrigeration cycle 11 is increased and the defrosting operation time of the circuit is shortened as in the fourth embodiment. The room temperature drop can be reduced, and comfort is increased.

It is a refrigerant circuit figure of the air harmony device showing Embodiment 1 of the present invention. It is a refrigerant circuit figure of the air conditioning apparatus which shows Embodiment 2 of this invention. It is a refrigerant circuit figure of the air conditioning apparatus which shows Embodiment 3 of this invention. It is a refrigerant circuit figure of the air conditioning apparatus which shows Embodiment 4 of this invention. It is a refrigerant circuit figure of the air conditioning apparatus which shows Embodiment 4 of this invention. It is a refrigerant circuit figure of the air conditioning apparatus which shows Embodiment 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st compressor, 2 1st four-way switching valve, 3 1st heat exchanger, 4a 1st ball valve, 4b 2nd ball valve, 4c 3rd ball valve, 4d 4th ball valve DESCRIPTION OF SYMBOLS 5 1st expansion device, 6 2nd heat exchanger, 7 1st connection piping, 8 2nd connection piping, 9 1st air blower, 10 2nd air blower, 11 1st freezing cycle, 21 2nd compressor, 22 2nd four-way selector valve, 23 3rd heat exchanger, 23a 5th heat exchanger, 24 2nd expansion device, 25 4th heat exchanger, 26 2nd freezing Cycle, 27 third blower, 28a first control device, 28b second control device, 29 communication line, 30 sixth heat exchanger, 31 bypass pipe, 32 first check valve, 33 second Check valve, 40 seventh heat exchanger, 41 accumulator.

Claims (4)

An outdoor unit having a first compressor, a first heat exchanger, a first expansion device, at least one indoor unit having a second heat exchanger, the indoor unit and the outdoor unit, A first connection pipe and a second connection pipe for connecting the first refrigeration cycle,
A second refrigeration cycle in which the second compressor, the third heat exchanger, the second expansion device, the fourth heat exchanger, and the sixth heat exchanger are connected by refrigerant piping. And having
The first connection pipe in the first refrigeration cycle, and the refrigerant pipe between the second expansion device and the sixth heat exchanger in the second refrigeration cycle are the fourth heat. Between the second connection pipe in the first refrigeration cycle and the second compressor and the fourth heat exchanger in the second refrigeration cycle so that heat can be mutually exchanged in the exchanger. Each of the refrigerant pipes is configured to be capable of exchanging heat with each other in the sixth heat exchanger,
During the defrosting operation of the first refrigeration cycle, the sixth heat exchanger heats the low temperature two-phase refrigerant of the first refrigeration cycle with the high temperature discharge refrigerant of the second refrigeration cycle. Air conditioner. The air conditioner according to claim 1, wherein a fourth heat exchanger in the second refrigeration cycle is provided inside or outside the outdoor unit. The first heat exchanger in the first refrigeration cycle and the third heat exchanger in the second refrigeration cycle are installed close to each other so that they can exchange heat with each other. The air conditioner according to claim 1 or 2. The air according to any one of claims 1 to 3, wherein the existing first connection pipe and the second connection pipe constituting the first refrigeration cycle are reusable. Harmony device.

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