JP2002106984A - Control method and replacement method of refrigerant circuit and refrigerant circuit device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When a refrigerant having a high operating pressure is used, it is necessary to increase the pressure resistance of refrigerant circuit components. In a large building having a complicated piping route, replacement of existing piping increases costs and waste. The problem of increase occurs. SOLUTION: A refrigerant circuit formed by connecting a compressor 1, a heat source side main heat exchanger 2a, a heat source side auxiliary heat exchanger 2b, flow control devices 3a, 3b, and use side heat exchangers 4a, 4b by piping,
Solenoid valves 27 and 28 for closing the flow of the refrigerant to the heat source side auxiliary heat exchanger 2b, a pressure sensor 20 for detecting the condensing pressure of the heat source side main heat exchanger 2a, and a pressure detected by the pressure sensor 20 An operation control unit 19 that controls opening and closing of the electromagnetic valves 27 and 28 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant circuit device such as an air conditioner or a refrigerator using a refrigerant having a high operating pressure.

[0002]

2. Description of the Related Art Offices and the like often have a multi-type air conditioner capable of operating a plurality of indoor units simultaneously or individually in order to individually air-condition a plurality of rooms. Has a long piping length, which requires bending and branching in the middle, and the piping shape is also complicated. Conventional air conditioners mainly use HCFC-based R22 refrigerant, and the components constituting the refrigerant circuit have specifications in which the strength is secured according to the operating pressure of the refrigerant used.
However, some of the refrigerants that have been conventionally used are not preferable from the viewpoint of global environmental protection. For this reason, switching to alternative refrigerants has been promoted. In the case of a relatively large-scale air conditioning system, H407-based R407C may be used as an alternative refrigerant because the pressure characteristics are similar to R22.

[0003]

In order to increase the efficiency of the refrigeration cycle and reduce the energy consumption, it is conceivable to use a refrigerant having the same temperature and a high density, that is, a high operating pressure. This is because the high density is expected to decrease the flow velocity in the pipe and reduce the pressure loss due to the decrease in the volume flow rate for the same mass flow rate. The performance of R407c is similar to that of R22 because the pressure characteristics of R407c are substantially the same as R22. Therefore, large energy saving cannot be expected as compared with the case where R22 is used.

Some of the alternative refrigerants have higher operating pressures (saturation pressures) at the same temperature than the R22 and R407C refrigerants, so the use of such refrigerants leads to energy savings, while the operating pressures increase. Accordingly, it is necessary to increase the pressure resistance of the refrigerant circuit components, which may lead to an increase in the cost of the air conditioner.

[0005] In addition, many years have passed since the use of R22, and the heat source unit and the indoor unit may be replaced with the aging of a conventionally provided product. In such a case, if an attempt is made to use a product corresponding to an alternative refrigerant having a higher operating pressure than the conventional refrigerant, it is necessary to change not only the heat source unit and the indoor unit but also the piping on the way to a thicker one. Since an air conditioner having a large maximum capacity is installed in a relatively large building, the pipe length becomes long even with one indoor unit, and it is difficult to replace the pipe if there is a bent portion in the middle. Further, in a system having a plurality of indoor units in one refrigerant circuit, since there is a branch part for each indoor unit in the middle of piping, replacing a large-sized piping system with a complicated shape requires a large amount of cost. Replacing existing pipes is not only economical,
Energy consumption for transporting, disposing of, and regenerating existing pipe waste generated from large buildings is required, which adversely affects global environmental conservation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to enable the use of a refrigerant having a high operating pressure even if a component constituting a refrigerant circuit has a low pressure resistance. I do.

[0007]

A method of controlling a refrigerant circuit according to the present invention is directed to a method of controlling a refrigerant as a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping. Replace with a high-pressure refrigerant and increase the condensation capacity so that the saturated pressure in the refrigerant circuit by the replaced refrigerant is lower than the pressure resistance of the component with the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement. Control.

In addition, the refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant, and the replaced refrigerant is used in the refrigerant circuit. The evaporation capacity is controlled so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement.

Further, according to the method of replacing a refrigerant circuit according to the present invention, a refrigerant as a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttling means, and an evaporator are sequentially connected by piping is changed to a higher-pressure refrigerant. The condenser is replaced with a condenser having a capacity such that the saturation pressure of the replaced refrigerant in the refrigerant circuit is equal to or less than the pressure resistance of the component having the lowest pressure resistance among the components used in the refrigerant circuit before and after the replacement.

[0010] In addition, the refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant. An evaporator whose capacity can be controlled so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement is replaced.

Further, the refrigerant which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping is replaced with a higher-pressure refrigerant, and the replaced refrigerant is used in the refrigerant circuit. The control means is replaced with a control means for controlling the pressure so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after the replacement.

Further, a refrigerant circuit device according to the present invention is configured through any one of the above-described methods for replacing a refrigerant circuit.

Further, a refrigerant circuit in which a compressor, a first condenser, a second condenser, a throttle means, and an evaporator are sequentially connected by piping, and a flow of the refrigerant to the second condenser is closed. Opening / closing means, pressure detecting means for detecting the condensing pressure of the first condenser or temperature detecting means for detecting the condensing temperature of the first condenser, and the pressure detected by the pressure detecting means or the temperature detection Control means for controlling the opening and closing of the opening and closing means according to the temperature detected by the means.

Further, the second condenser is a water-cooled condenser.

Further, the second condenser is a cold heat storage tank.

Further, the second condenser has an evaporator of another refrigerant circuit and can exchange heat with each other.

A refrigerant circuit in which a compressor, a condenser, a throttling means and a plurality of evaporators arranged in parallel are sequentially connected by piping; a pressure detecting means for detecting a condensing pressure of the condenser; When the pressure detected by the pressure detection means exceeds a predetermined value, a control means is provided for reducing the evaporation capacity of a part or all of the plurality of evaporators.

The refrigerant to be used is R22 or R4
This refrigerant is a refrigerant other than 07C and has a pressure characteristic higher than that of R22 or R407C at the same temperature at the same saturated pressure.

A refrigerant circuit in which a plurality of compressors, condensers, throttling means, and evaporators are sequentially connected by piping, a refrigerant to be used is other than R22 and R407C, and a saturation pressure with respect to an arbitrary temperature is reduced. Refrigerant R22 or refrigerant R4
When using a refrigerant having a higher saturation pressure characteristic than either one of the compressors, the control means is capable of individually controlling the operation of the plurality of compressors.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a refrigerant circuit diagram of an air conditioner according to Embodiment 1 of the present invention. In the figure, 1 is a compressor, 16 is a four-way valve, 2a is an air-cooled heat source side heat exchanger, 2b is a water-cooled heat source side auxiliary heat exchanger, 3a and 3b are flow control valves, 4a and 4b. Is a use side heat exchanger, 27 and 28 are solenoid valves for closing the heat source unit side auxiliary heat exchanger 2b, and 20 is a pressure sensor for detecting the pressure on the high pressure side of the compressor. These are connected by refrigerant piping,
It constitutes a refrigerant circuit. Among the refrigerant pipes, the four-way valve 16
~ Part between the use side heat exchangers 4a and 4b, the flow control valve 3
A part between a, 3b and the heat source unit side main heat exchanger 2a or the heat source unit side auxiliary heat exchanger 2b is buried in the wall of the building or arranged behind the ceiling.

The heat source unit-side auxiliary heat exchanger 2b is of a water-cooled type capable of exchanging heat between a refrigerant and cooling water, and water as a cooling fluid is always supplied from outside. The refrigerant used in this refrigerant circuit uses R410A, which is an HFC-based mixed refrigerant. R410A has a higher saturation pressure at the same temperature than the R22 refrigerant conventionally used mainly in air conditioners, so that the operating pressure in the condenser also increases. In the case of R22, which is a conventional refrigerant, when the high pressure exceeds 3 MPa, abnormal stop is performed, and the pressure is prevented from rising any more. In a building in which an air conditioner for R22 has been used for a long time, When an air conditioner compatible with R410A is used, if the operating pressure does not exceed 3 MPa, existing piping remaining in the building can be reused as it is. The practice arrows in the figure indicate the flow of the refrigerant during cooling,
Dashed arrows indicate the flow direction of the refrigerant during heating.

FIG. 2 is a control block diagram of each component in FIG. The operation control unit 19 receives signals for operating and stopping the use-side heat exchangers 4a and 4b by the remote controllers 5a and 5b.
It also receives an input from the pressure sensor 20. Then, the operation control unit 19 starts and stops the compressor 1, the four-way valve 16, the flow valve 3 a,
b, and outputs the opening and closing of the solenoid valves 27 and 28. In addition,
The four-way valve 16 is turned off for cooling (solid arrow direction circuit),
On turns to heating flow, solenoid valves 27 and 28 open on,
The solenoid valve is off and closed.

The refrigerant circuit constructed as described above has an R2
2 The refrigerant is extracted from the existing refrigerant circuit using the refrigerant, and then the compressor and the heat source side heat exchanger are separated from the pipe, and the heat source side main heat exchanger 2a in which the R410A refrigerant is sealed from the compressor 1 and the heat source instead. Side auxiliary heat exchanger 2b,
The components up to the solenoid valve 28 are connected. If necessary, the use-side heat exchanger and the flow valve are disconnected from the pipe, and new use-side heat exchangers 4a and 4b and new flow valves 3a and 3b are connected instead. By replacing such a refrigerant circuit, of the existing refrigerant pipes, a part between the four-way valve 16 and the use-side heat exchangers 4a and 4b, which are buried in the wall of the building or disposed behind the ceiling, Flow control valves 3a, 3b ~
Heat source unit side main heat exchanger 2a or heat source unit side auxiliary heat exchanger 2
The part between b is used as it is.

The compressor 1 to the four-way valve 16 to the heat source unit side main heat exchanger 2a or the heat source unit side auxiliary heat exchanger 2b to the solenoid valve 28 are unitized as a heat source side unit such as an outdoor unit. , Equipped in this unit,
The operation control unit that controls the operation frequency of the compressor and the opening / closing and opening of various valves is also replaced at the same time. Before and after the replacement, the heat source side heat exchanger, the use side heat exchanger, the operation control unit, the operating pressure (saturation pressure) in the refrigerant circuit after the replacement,
A refrigerant circuit capable of operating so as not to exceed the operating pressure (saturation pressure) of the refrigerant circuit before replacement is selected and installed.

FIG. 3 is a control flowchart of the operation control unit 19 of the air conditioner of the present invention. First step 0
It is assumed that the remote control operation is performed. In step s1, on / off of the remote controller 5a is confirmed. Remote control 5a is on
If so, in step s2, the flow valve 3a is opened to allow the refrigerant to flow. If the remote controller 5a is not on, the flow valve 3a is closed in step s3.

Next, at step s4, the remote controller 5b is turned on / off.
Check off. Here, the same check is performed as with the remote controller 5a. However, if the remote controller 5b is not on, it is checked whether the remote controller 5a is on in step s7.
If the remote controller 5a is not turned on, the operation is not performed because all the remote controllers are actually turned off due to an operation error or the like, and the operation is stopped at step s8. If it is confirmed by step 6 that any one of the remote controllers is on, it is determined in step s6 whether the input mode of the remote controller is cooling or heating. If the mode is the heating mode, the process proceeds to step s10, but the subsequent operations are omitted.

In the case of the cooling mode, the process proceeds to step s11, where the four-way valve 16 is turned off, and in step s12, the solenoid valves 27 and 28 are both turned off. Not to flow. Next, the compressor 1 is operated in step s13. Then, in step s14, the pressure is detected by the pressure sensor 20. The detection position of the pressure sensor 20 is the heat source device side heat exchanger 2
a, 2b, and the difference in piping pressure loss is only slight, so that it can be treated as equivalent to the condensing pressure.

In step s15, once the solenoid valves 27, 2
Check the status of 8. This is because the determination conditions for opening and closing the solenoid valves 27 and 28 are distinguished in steps s16 and s17. In step s15, the solenoid valves 27 and 28 are turned off.
If it is determined to be f, the process proceeds to step s17, and it is determined whether or not the detected pressure (HPS) of the pressure sensor 20 exceeds 2.7 MPa. Here, the conventional refrigerant R22
In the case of (3), the upper limit is 3 MPa, but the judgment pressure is set to be as low as 2.7 MPa in case of a sudden rise in pressure.

If the pressure exceeds 2.7 MPa, the solenoid valves 27 and 28 are turned on in step s19 to suppress the high pressure. When the solenoid valves 27 and 28 are turned on, the refrigerant flows through the auxiliary heat exchanger 2b, so that heat exchange with the cooling water starts. In the case of R410A, when the condensing pressure reaches 2.7 MPa, the condensing temperature is around 45 ° C. The air temperature changes depending on the season and place.However, if cooling water that is not easily affected by the temperature of air, such as groundwater, is used, or if it is supplied from a water source that is guaranteed to be sufficiently lower than the air temperature, air The condensation temperature of the refrigerant is lower than that of the heat source device side heat exchanger 2a using the heat source. Therefore, the pressure decreases without the condensing pressure approaching the upper limit of 3 MPa.

Once the solenoid valves 27 and 28 are opened, s
14 is repeated, and in step s16, 2.5
When the pressure drops below MPa, the solenoid valves 27 and 28 are turned on again.
ff (step s18). Steps s16 and s1
The reason why the pressure determination value is changed in step 7 is to prevent the solenoid valves 27 and 28 from being repeatedly opened and closed due to a change in pressure when the same determination value is used. In particular, in a refrigerant such as R410A having a high operating pressure, the pressure fluctuation width due to the same temperature difference becomes narrow in a high temperature range,
Since the pressure change becomes large even with a small temperature change, it is necessary to provide a pressure difference for such a determination value.

As described above, by using the auxiliary heat exchanger 2b on the heat source unit side in accordance with the condensing pressure to suppress the increase in the condensing pressure, the wall thickness is increased and the material is changed to ensure the pressure resistance of the refrigerant piping parts. It is possible to suppress an increase in the cost of the product without the necessity. In addition, it is possible to divert existing piping with complicated shapes in buildings that had been used with conventional refrigerants with alternative refrigerants, reducing piping costs, construction costs, and suppressing energy loss due to disposal. It can also contribute to environmental conservation.

In order to estimate the condensation pressure from the temperature,
Instead of the pressure sensor 20, a temperature sensor is attached to the heat source unit side heat exchanger 2a or a refrigerant pipe in the vicinity thereof to detect a condensing temperature (not shown), and a predetermined value of the condensing temperature (for example, R410A refrigerant 2) The same operation and effect can be obtained even if the on / off control of the solenoid valves 27 and 28 is performed at 43 ° C. for 0.7 MPa or 41 ° C. for 2.5 MPa).

Embodiment 2 FIG. FIG. 4 shows a refrigerant circuit diagram of an air conditioner according to Embodiment 2 of the present invention. In FIG. 4, reference numeral 1 denotes a compressor, 2a denotes an air-cooled heat source side main heat exchanger, and 2b denotes a heat source side auxiliary heat exchanger having an ice heat storage tank. Heat can be exchanged with the refrigerant. 3a, 3b are flow control valves, 4a, 4
b is a use side heat exchanger, 16 is a four-way valve, 11 is an electromagnetic valve on a pipe taken out between the four-way valve and the heat source unit main heat exchanger 2a, and 12 is a heat source unit side main heat exchanger 2a. An electromagnetic valve 13 on a pipe connecting the flow rate control valves 3a and 3b is provided in a heat source side auxiliary heat exchanger 2b on a pipe connecting the heat transfer pipe 7 and a pipe connecting the solenoid valve 12 and the flow rate control valves 3a and 3b. It is a solenoid valve.

Reference numeral 14 denotes one end of the heat transfer tube 7 and the use side heat exchanger 4
a solenoid valve provided on a pipe connecting a, 4b and a pipe connecting the four-way valve 16, a solenoid valve 15 is provided on the pipe connecting the heat source side main heat exchanger 2a to the flow control valves 3a, 3b; A flow control valve provided in the middle of the pipe from the near side to the heat transfer pipe 7 in the heat source side auxiliary heat exchanger 2b, 27 and 28 are solenoid valves provided at the entrance and exit of the heat source unit side main heat exchanger 2a, and 20 is a compression valve. The pressure sensor 21 for detecting the discharge pressure of the machine 1 is a temperature sensor for detecting the temperature of ice or water inside the heat source side auxiliary heat exchanger 2b. The solenoid valves 11 to 14, 27, and 28 are all open when on and closed when off.

FIG. 5 is a control block diagram of the air conditioner according to the present invention. In the figure, reference numeral 19 denotes an operation controller, which receives an input from the remote controllers 5a and 5b, determines operation stop, and controls the use-side heat exchangers 4a and 4b for cooling.
A decision is made to switch the mode of heating. Further, the compressor 1, the four-way valve 16, the flow control valves 3 a, 3 b, 15, the solenoid valves 11, 1 receive the input of the pressure sensor 20, the water temperature sensor 21 and the information of the timer 22.
The control of 2, 13, 14, 25, 26 is performed.

In this refrigerant circuit, compared to R22,
R410A, which is a refrigerant having a high saturation pressure at the same temperature, is sealed. The refrigerant circuit configured as described above has R
Extract refrigerant from the existing refrigerant circuit using 22 refrigerant,
Thereafter, the section from the compressor to the heat source side heat exchanger is cut off from the pipe, and instead the heat source side main heat exchanger 2a to the solenoid valve 12 and the heat source side auxiliary heat exchanger 2b to the solenoid valve 13 in which the R410A refrigerant is sealed from the compressor 1. And the respective components up to the solenoid valve 14 are connected.

If necessary, the use-side heat exchanger and the flow valve are disconnected from the piping, and new use-side heat exchangers 4a and 4b and flow valves 3a and 3b are connected instead. By replacing such a refrigerant circuit, of the existing refrigerant pipes, a part between the four-way valve 16 and the use-side heat exchangers 4a and 4b, which are buried in the wall of the building or disposed behind the ceiling, A part between the flow control valves 3a, 3b and the solenoid valves 12, 13 is used as it is.

The compressor 1 to the four-way valve 16 to the heat source unit side main heat exchanger 2 a to the solenoid valve 12 and the heat source unit side auxiliary heat exchanger 2 b to the solenoid valves 13 and 14 are, for example, heat source side units such as outdoor units. The operation control unit that controls the operating frequency of the compressor and the opening / closing and opening of various valves is also replaced at the same time. Before and after the replacement, the heat source side heat exchanger, the use side heat exchanger, and the operation control unit determine that the operating pressure (saturation pressure) of the refrigerant circuit after replacement exceeds the operating pressure (saturation pressure) of the refrigerant circuit before replacement. Those that have the ability to operate without being selected are selected and installed.

Here, the operation of generating ice in the ice heat storage tank of the heat source side auxiliary heat exchanger 2b will be described with reference to the refrigerant circuit diagram of FIG. The ice generation operation is usually performed at night (midnight power). This is determined by the timer 21 at time 22: 0.
When the operation control unit 19 confirms that the value has become 0, the operation is started. First, the compressor 1 is stopped irrespective of whether the remote controllers 5a, 5b are running or stopped, and the flow control valves 3a, 3b
Is fully closed, the solenoid valve 12 is off, and the four-way valve 16 is off, and the cooling cycle direction is set. At the same time, the solenoid valves 11 and 13 are turned off, and the 14, 25 and 26 are turned on. Then, the flow control valve 15 is also opened. That is, the refrigerant flowing out of the compressor 1 flows from the four-way valve 16 through the heat source unit side main heat exchanger 2a,
5, a circuit is formed that flows through the heat transfer tube 7, the solenoid valve 14 and the four-way valve 16 to the compressor 1 again.

Then, the operation control section 19 starts the compressor 1, and the high-temperature and high-pressure gas refrigerant is condensed in the heat-source-unit-side main heat exchanger 2a, and the liquid refrigerant is reduced in pressure by the flow control valve 15,
It becomes a low-temperature two-phase refrigerant and reaches the heat transfer tube 7. Water is contained in the ice heat storage tank, and the temperature is lowered by the low-temperature refrigerant flowing through the heat transfer tube 7. When the temperature falls below the freezing point, the phase changes from water to ice, and ice is generated. The refrigerant that has exited the heat transfer tube 7 becomes a low-pressure gas refrigerant, and returns to the compressor 1 again through the electromagnetic valve 14 and the four-way valve 16. Ice is generated in the ice heat storage tank in this manner. Eight hours have elapsed since the start of ice generation by the timer 22 or six hours have elapsed since the water temperature detected by the water temperature sensor 21 reached the freezing point. At the stage,
It is determined that sufficient ice has been generated, and the ice generation operation ends.

In order to reduce the condensation pressure at the time of ice formation, an auxiliary heat exchanger 2c is provided during the ice formation operation as shown in FIG. 6, and the front and rear solenoid valves 27 and 28 are turned on to open the refrigerant. May be added to increase the condensation capacity. The auxiliary heat exchanger 2c may be an air-cooled type, but a water-cooled type heat exchanger can use groundwater or the like having a lower temperature than air, and has a large effect on lowering the condensing pressure because the heat source temperature decreases. .

Next, the control of the condensing pressure during the cooling operation will be described with reference to the refrigerant circuit of FIG. 4 and the control flowchart of the operation control unit 19 of FIG. First, from step s20 to s
Steps up to 30 are the same as steps s0 to s10 in FIG. 3 in the first embodiment of the present invention, and a description thereof will not be repeated. When the operation control unit 19 determines that the air conditioner is cooling in step s29, the four-way valve 16 is turned off in step s31. And
In step s32, the solenoid valves 12, 25, and 26 are turned on, and in step s33, the solenoid valves 11, 13, and 14 are turned off. As a result, the heat source unit side main heat exchanger 2a acts as a condenser, and the flow control valve 15 is closed in step s34, so that the refrigerant does not flow into the ice heat storage tank. Then, in Step 35, the compressor 1 is started.

After starting the compressor 1, the high pressure of the compressor 1 is always detected by the pressure sensor 20 in step s36. Since the high pressure of the compressor 1 is almost equal to the condensing pressure, it is used for controlling the condensing pressure. The condensing pressure control is as follows.
In step s37, it is determined whether or not the heat source unit side auxiliary heat exchanger 2b is already used, based on the open / closed state of the solenoid valves 11, 13. When the electromagnetic valves 11 and 13 are opened, the high-pressure refrigerant that has passed through the four-way valve 16 flows to the heat transfer tube 7 so that heat can be exchanged with ice in the ice heat storage tank of the heat source unit-side auxiliary heat exchanger 2b.
In step s39, the pressure HP detected by the pressure sensor 20
It is determined whether S does not exceed 2.7 MPa.

If the pressure exceeds 2.7 MPa, in order to reduce the condensation pressure, the solenoid valve 1 is turned on at step s40.
Open 1, 13. As a result, the ice heat storage tank acts as a condenser, and can exchange heat with ice near the freezing point lower than the air temperature or ice water, so that the condensation temperature is greatly reduced.
Once the solenoid valves 11 and 13 are opened, step s
At 36, pressure detection is performed, and at steps s37 and s38, it is determined whether or not the pressure HPS is less than 2.5 MPa. If it is detected in step s38 that the pressure is less than 2.5 MPa, the process proceeds to step s41, in which the solenoid valves 11 and 13 are turned off.
ff, the air-cooled heat source unit side heat exchanger 2
Cooling is performed in the use-side heat exchangers 4a and 4b in a refrigeration cycle using only a as a condenser.

The reason why the pressure for using the ice heat storage tank 2b as a condenser is in the range of 2.7 to 2.5 MPa is that the threshold value of the pressure for opening and closing the solenoid valves 11 and 13 is set to 1
In this case, the frequent opening and closing of the solenoid valve may prevent hunting. As another reason, if the frequency of using the ice heat storage tank is increased and the use time is lengthened, the heat stored as ice naturally increases, and the ice melts and the water temperature rises in a short time. For this reason, the use frequency of the ice heat storage tank is limited to a pressure condition higher than 2.5 MPa so that the operation of sufficiently reducing the pressure during the cooling time period becomes possible. Of course, if a sufficiently large ice heat storage tank is obtained, the condenser during the cooling operation is mainly composed of the ice heat storage tank or only the ice heat storage tank (at this time, the solenoid valves 25 and 26 are closed). In addition, it is possible to perform operation with a low condensing pressure for a long time.

As described above, by utilizing the condensing action selected by heat exchange with ice when the condensing pressure is increased, the pressure can be sufficiently suppressed, and compared with R22 which is one of the conventional refrigerants. Even when R410A having a high operating pressure is used, there is no need to increase the pressure resistance of the equipment or to replace the existing piping, so that a product excellent in economy and energy saving can be obtained.

In the case where a material capable of storing cold heat due to solidifying action such as ice is used, its temperature is stable until melting, so that stable performance can be expected as a condensing action, and stable operation of the air conditioner can be expected. Is secured, and a highly reliable product can be obtained. Although the heat source unit side heat exchanger 2a and the heat source unit side auxiliary heat exchanger 2b are in a parallel relationship in FIG. 5, the branch to the solenoid valve 11 is taken from the downstream of the solenoid valve 28 as shown in FIG. The same operation and effect can be obtained even if the relationship between the heat source unit side heat exchanger 2a and the heat source unit side auxiliary heat exchanger 2b is set in series.

Embodiment 3 FIG. 9 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 3 of the present invention. FIG.
1, 1 is a compressor, 16 is a four-way valve, 2a is an air-cooled heat source side main heat exchanger, 2b is a heat source side auxiliary heat exchanger, 3
a, 3b are flow valves, 4a, 4b are use side heat exchangers, 2
Reference numerals 7 and 28 denote solenoid valves for closing the heat source unit side auxiliary heat exchanger 2b, and reference numeral 20 denotes a pressure sensor for detecting high pressure of the compressor. Further, a compressor 31, a condenser 32, a flow control valve 3
3. A refrigerant circuit is separately formed by the heat source unit side auxiliary heat exchanger 2b.

Here, the heat source unit side auxiliary heat exchanger 2b includes a refrigerant circuit (hereinafter, referred to as a main refrigerant circuit) having the compressor 1,
A refrigerant circuit having a compressor 31 (hereinafter referred to as a sub refrigerant circuit)
Are shared by the two refrigerant circuits, and heat exchange between the respective refrigerant circuits is possible. In the main refrigerant circuit, R4
10A, R410A is also sealed in the slave refrigerant circuit. The four-way valve 16 becomes a circuit on the cooling side when it is off, and the solenoid valves 27 and 28 are open when on and closed when off. FIG.
FIG. 2 is a control block diagram of the air conditioner according to the present invention, in which an operation control unit 19 controls components of a main refrigerant circuit and components of a sub-refrigerant circuit.

The refrigerant circuit configured as described above has an R2
2 The refrigerant is extracted from the existing refrigerant circuit using the refrigerant, and then the compressor and the heat source side heat exchanger are separated from the pipe, and the heat source side main heat exchanger 2a in which the R410A refrigerant is sealed from the compressor 1 and the heat source instead. Side auxiliary heat exchanger 2b,
The components up to the solenoid valve 28 are connected. If necessary, the use-side heat exchanger and the flow valve are disconnected from the pipe, and new use-side heat exchangers 4a and 4b and new flow valves 3a and 3b are connected instead. By replacing such a refrigerant circuit, of the existing refrigerant pipes, a part between the four-way valve 16 and the use-side heat exchangers 4a and 4b, which are buried in the wall of the building or disposed behind the ceiling, Flow control valves 3a, 3b ~
Heat source unit side main heat exchanger 2a or heat source unit side auxiliary heat exchanger 2
The part between b is used as it is.

The compressor 1 to the four-way valve 16 to the heat source unit side main heat exchanger 2a or the heat source unit side auxiliary heat exchanger 2b to the solenoid valve 28 are unitized as a heat source side unit such as an outdoor unit. , Equipped in this unit,
The operation control unit that controls the operation frequency of the compressor and the opening / closing and opening of various valves is also replaced at the same time. Before and after the replacement, the heat source side heat exchanger, the use side heat exchanger, the operation control unit, the operating pressure (saturation pressure) in the refrigerant circuit after the replacement,
A refrigerant circuit capable of operating so as not to exceed the operating pressure (saturation pressure) of the refrigerant circuit before replacement is selected and installed.

Further, when the outdoor unit is replaced, it is arranged in the same unit as the outdoor unit or the compressor 3
1, a sub-refrigerant circuit in which the condenser 32 and the flow control valve 33 are formed as separate units is also provided at the same time.

Here, the operation will be described.
9 will be described with reference to the control flowchart of FIG. FIG.
, Steps s42 to s52 are the same as steps s0 to s10 in FIG. 3, and a description thereof will be omitted. If it is determined in step s51 that the air conditioner is in the cooling mode, then in step s53, the four-way valve 16
Is turned off, and the solenoid valves 27 and 28 are also turned off so that the refrigerant flows only to the heat source device side main heat exchanger 2a (steps s53 and s54). After starting the compressor 1 in step s55, a high pressure, that is, a condensing pressure is detected by the pressure sensor 20 in step s56.

In step s57, it is determined whether or not the high pressure reduction control is being performed based on whether or not the solenoid valves 27 and 28 are open. When the solenoid valves 27 and 28 are off, the detected value of the pressure sensor is 2.7 MP in step s60.
Check if it does not exceed a. If it has exceeded, the process proceeds to step s61 to start the high pressure reduction control. In the high pressure reduction control, first, in step s61, the flow control valve 33 of the slave refrigerant circuit is opened, and then the solenoid valves 27 and 28 are opened. Then, in step s63, the compressor 31 is turned on.
Accordingly, in the slave refrigerant circuit, the high-temperature, high-pressure gas refrigerant discharged from the compressor 31 is condensed in the condenser 32 to become a high-pressure liquid refrigerant. And flows into the heat source unit side auxiliary heat exchanger 2b.

The low-temperature, low-pressure two-phase refrigerant absorbs heat from the high-temperature, high-pressure refrigerant in the main refrigerant circuit inside the heat source unit-side auxiliary heat exchanger 2b, and returns to the compressor 32 as a low-pressure gas refrigerant. In the main refrigerant circuit, heat is radiated by the heat source unit-side auxiliary heat exchanger 2b. However, since the temperature of the refrigerant in the heat source unit-side auxiliary heat exchanger 2b by the sub-refrigerant circuit is sufficiently lower than the air temperature, the condensation effect is greater than air cooling. Therefore, the condensing pressure of the main refrigerant circuit decreases. In FIG. 11, once the solenoid valves 27 and 28 are once opened, the process proceeds from step s57 to step s59, where the condensing pressure HPS detected by the pressure sensor 20 is 2.5MPa.
The condensing action of the heat source unit side auxiliary heat exchanger 2b by the sub-refrigerant circuit is continuously used until the temperature falls below a.

If the capacity of the compressor 31 of the slave refrigerant circuit can be controlled, the flow of the capacity control shown in FIG.
The cooling capacity of the heat source unit side auxiliary heat exchanger 2b can be variably controlled. In FIG. 12, when the compressor 31 is operated in step s67, the process proceeds to step s68 and step s
At 70, the compressor capacity is varied depending on whether the condensing pressure HPS of the main refrigerant circuit is higher than 2.6 MPa.

If the pressure is higher than 2.6 MPa, the compressor 31
Is increased by 5% (step 71), 2.6 MPa
If lower, the compressor frequency is reduced by 5% (step 72). In this way, when the condensing pressure in the main refrigerant circuit is higher than 2.6 MPa, the condensing capacity in the main refrigerant circuit is increased by increasing the evaporation capacity in the sub-refrigerant circuit, and conversely in the main refrigerant circuit. When the condensing pressure is lower than 2.6 MPa, the condensing pressure is lower than a predetermined value and the stable operation is performed by lowering the condensing capacity in the main refrigerant circuit by lowering the evaporation capacity in the sub refrigerant circuit. It can be implemented.

Thus, by providing the heat source unit side auxiliary heat exchanger 2b in the main refrigerant circuit and realizing this cooling function in the sub-refrigerant circuit, cooling at a lower temperature than air becomes possible, which is effective in lowering the condensing pressure. Becomes If the compressor 32 of the slave refrigerant circuit is variable, fine and stable control can be performed, and reliability and comfort are improved. The main refrigerant circuit can be realized by a component configuration having the same pressure resistance strength as that of the R22 refrigerant, and the main refrigerant circuit can be manufactured at low cost. In addition, the existing piping provided for the refrigerant having a low operating pressure can be used economically. It is.

Embodiment 4 FIG. FIG. 13 is a refrigerant circuit diagram showing an air conditioner according to Embodiment 4 of the present invention. FIG. 13 is provided with an outside air temperature sensor 23 for detecting the temperature of the air flowing through the heat source unit side main heat exchanger 2a instead of the pressure sensor 20 in FIG. 1 in the first embodiment. The method of replacing the circuit is the same as that of FIG. FIG. 14 is a control block diagram according to the present invention, and includes an outside air temperature sensor 23 instead of the pressure sensor 20 in FIG. In the present invention, R410A refrigerant is used.

The operation according to the present invention is as shown in the control flowchart of the operation control unit 19 in FIG.
The operation is the same as the control in FIG. 3 using the pressure sensor 20, and therefore, only the differences will be described here. In FIG. 15, when the compressor 1 is started in step s85, the outside air temperature TA detected by the outside air temperature sensor 23 is detected in step 86. At step s87, the solenoid valves 27, 2
By checking the state of 8, it is confirmed whether or not the condensation pressure lowering operation using the heat source unit side auxiliary heat exchanger 2b has already been performed. When the solenoid valves 27 and 28 are OFF, the heat source unit side auxiliary heat exchanger 2b is not used, so that the determination at the outside air temperature TA is performed in step s89.

If the outside air temperature exceeds 30 ° C., the condensing pressure may exceed 2.7 MPa and approach 3 MPa.
7 and 28 are opened to promote the reduction of the condensation temperature. This is because, from the characteristics of the R410A refrigerant, the saturation pressure at about 30 ° C., which is the same as the outside air temperature, is slightly lower than 2 MPa, and the temperature of the refrigerant in the heat source device side main heat exchanger 2a becomes higher than the air temperature. The difference between the air temperature and the refrigerant saturation temperature to 10
~ 15 ° C is expected, so the refrigerant temperature is 40 ° C
This is because the pressure becomes approximately 45 ° C., that is, a pressure close to 3 MPa.
Naturally, a refrigerant having a higher operating pressure at the same temperature than R22
In the case of a refrigerant other than the 410A refrigerant, the reference temperature for opening and closing the solenoid valves 27 and 28 may be changed according to the pressure-temperature characteristics.

After opening the solenoid valves 27 and 28 in step s91, the outside air temperature is detected in step s86.
The process proceeds from step s87 to step s88, in which the solenoid valves 27 and 28 are kept open until the outside air temperature TA falls below 20 ° C. As described above, by using the outside air temperature sensor 23 and determining whether to use the sub heat exchanger 2b in accordance with the temperature of the cooling fluid of the heat source device side main heat exchanger 2a, an inexpensive device can be used. It is possible to suppress the condensation pressure. In addition, due to the suppression of the condensing pressure, there is no need to increase the strength of the refrigerant circuit parts even when using a refrigerant having a high operating pressure as compared with a conventionally used R22 refrigerant or the like. It can be used as it is, and it is possible to provide a product with excellent economic efficiency.

Embodiment 5 FIG. FIG. 16 is a refrigerant circuit diagram showing an air conditioner according to Embodiment 5 of the present invention. In the figure, 1 is a compressor, 16 is a four-way valve, 2a is a heat source side main heat exchanger, 3a and 3b are flow control valves, 4a and 4b are use side heat exchangers, and 20 is a high pressure side of the compressor. Pressure sensor. FIG. 17 is a control block diagram of FIG.
The flow control valves 3a and 3b can be individually controlled.
The refrigerant used in this refrigerant circuit uses R410A which is a mixed refrigerant. The method of replacing the refrigerant circuit is the same as in the first embodiment, and a description thereof will not be repeated. The practice arrows in the figure indicate the flow of the refrigerant during cooling, and the dashed arrows indicate the flow direction of the refrigerant during heating.

FIG. 18 is a control flowchart of the operation control unit 19 in the air conditioner of the present invention. The operation of the present invention will be described with reference to FIG. First, control of this operation is started from step s92 when the power is turned on. Steps
At 93, it is determined whether the compressor 1 is operating. If the compressor 1 is operating, the process proceeds to step s94, and it is determined whether the operation is the cooling operation.

In the case of the cooling operation, in step s95, the high pressure HPS detected by the pressure sensor 20 becomes 2.5.
It is determined whether or not the pressure is MPa. If the HPS exceeds 2.5 MPa, it is determined in step s96 whether the flow control valve 3a is open. That is, it is determined whether the use-side heat exchanger 4a functions as an evaporator. If the flow control valve 3a is open, the opening is reduced by 10% in step s98. If the flow control valve 3a is not open, that is, if the refrigerant is not flowing through the use side heat exchanger 4a, the opening of the other flow control valve 3b is reduced by 10% (step s97).

As described above, the flow control valve 3a or 3b
By reducing the opening degree of the refrigerant, the flow rate of the refrigerant decreases, and the evaporation capacity decreases. As a result, the amount of refrigerant discharged from the compressor 1 also decreases. That is, since the flow rate of the refrigerant condensed in the heat source unit side main heat exchanger 2a also decreases, the effect of reducing the condensing pressure, that is, the high pressure, is obtained.

The reason why the flow control valve 3a is preferentially reduced is that in the case of a multi-type air conditioner of a large building, the necessity of the cooling capacity varies depending on the use of the installed room. For evaporators in rooms that cannot reduce the flow rate, the flow rate is not reduced, and the flow rate is reduced preferentially in the rooms that do not allow the reduction in high pressure while ensuring the minimum necessary air conditioning. .
For the determination of the priority order, a method of providing a priority order selection switch (not shown) in the operation control unit 19 and giving a priority order may be mentioned.

In step s99, H
If the PS exceeds 2.7 MPa, it is determined that there is a high urgency to reduce the high pressure, and the flow control valve 3a is used to reduce the flow rate of each of the connected and operating use-side heat exchangers 4a and 4b. , 3b are simultaneously reduced by 10% (steps s100, s101). In this way, the effect of reducing the high pressure is increased by increasing the amount of decrease in the flow rate.

As described above, in the air conditioner having a plurality of use-side heat exchangers, the necessary or minimum cooling is achieved by lowering the evaporation capacity of part or all of the use-side heat exchangers in accordance with the condensing pressure. Since the increase in condensing pressure can be suppressed by reducing the capacity, even if an alternative refrigerant having a higher operating pressure is used than R22, which is a conventional refrigerant, the component strength is not increased, and a large-scale, complicated path is used. Can be reused without having to replace the existing piping having a high pressure resistance, it is possible to provide an air conditioner excellent in reliability, economy and environment. In the present embodiment, the number of use-side heat exchangers is two. However, in the case of one or three or more heat exchangers, the operation and effect due to the reduction of the evaporation capacity can be obtained similarly.

Embodiment 6 FIG. FIG. 19 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 6 of the present invention. 1
a, 1b are compressors connected in parallel, 16 is a four-way valve, 2
a is a heat source side main heat exchanger, 3a and 3b are flow control valves, 4
Reference numerals a and 4b denote user-side heat exchangers, and reference numeral 20 denotes a pressure sensor for detecting the high pressure side of the compressor. FIG. 20 is a control block diagram of FIG. 19, and the compressors 1a and 1b can be individually controlled. The refrigerant used in the refrigerant circuit is
R410A which is a mixed refrigerant is used. The method of replacing the refrigerant circuit is the same as in the first embodiment, and a description thereof will not be repeated. The practice arrows in the figure indicate the flow of the refrigerant during cooling,
Dashed arrows indicate the flow direction of the refrigerant during heating.

FIG. 21 is a control flowchart of the operation control unit 19 of the present invention. In FIG. 21, step s
Steps from 102 to s112 are the same as steps 0 to s10 in FIG. If the cooling operation is determined in step s112, the four-way valve 16 is turned off in step s113 to perform the cooling cycle, and the compressors 1a and 1b are started in steps s114 and s115. After starting the compressor, pressure detection is performed in step s116, and in step s117, it is determined whether the value exceeds 2.7 MPa.
When the pressure exceeds 2.7 MPa, the compressor 1b is stopped to suppress the pressure rise (step s11).
8). Once the compressor 1b is stopped, step s
After the pressure detection at 116, the compressor 1b is not restarted until the high pressure HPS falls below 2.5 MPa in steps s117 and s119.

As described above, in an air conditioner using a refrigerant such as R410A having a higher operating pressure than a refrigerant such as R22, the same refrigerant circuit is constituted by a plurality of compressors. By stopping some,
Since the flow rate of the refrigerant is greatly reduced, even when the load suddenly increases or the condensing capacity decreases due to a rise in the temperature of the cooling fluid in the condenser, the pressure can be immediately reduced without reducing the capacity to zero. It is possible to use components with relatively low pressure resistance and to reuse pipes in existing buildings without changing them to those with high pressure resistance. Products can be provided.

In order to estimate the condensation pressure from the temperature,
Instead of the pressure sensor 20, a temperature sensor is attached to the heat source unit side heat exchanger 2a or a refrigerant pipe in the vicinity thereof to detect a condensing temperature (not shown), and a predetermined value of the condensing temperature (for example, R410A refrigerant 2) The same operation and effect can be obtained even if the on / off control of the solenoid valves 27 and 28 is performed at 43 ° C. for 0.7 MPa or 41 ° C. for 2.5 MPa).

In each of the above embodiments, R41 is used as the refrigerant.
Although an example using 0A is shown, the refrigerant is not limited to this, and may be a flammable refrigerant such as R32, and other refrigerants whose operating pressure is higher than the refrigerant before replacement after refrigerant replacement. If it is, the same effect can be obtained. In the embodiment described above, the control determination pressure for suppressing the high pressure is set to 3 MPa of the high pressure upper limit considered for the R22 refrigerant.
As described below, when the pressure resistance of the existing pipe exceeds 3 MPa, the existing pipe can be continuously used even if the control determination pressure is increased within a range not exceeding the pressure resistance, and the same effect is obtained. Present.

[0075]

As described above, according to the present invention, the refrigerant, which is the working fluid in the refrigerant circuit in which the compressor, the condenser, the throttle means, and the evaporator are sequentially connected by piping, is converted into a higher-pressure refrigerant. Replacement, since the saturation pressure in the refrigerant circuit due to the refrigerant after the replacement, the condensing capacity is controlled so as to be equal to or less than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after the replacement. Even in a refrigerant circuit having a low pressure resistance, a refrigerant having a high operating pressure can be used due to the condensing ability.

The refrigerant, which is the working fluid in the refrigerant circuit in which the compressor, the condenser, the throttle means, and the evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant. Since the evaporation pressure is controlled so that the saturation pressure is equal to or lower than the pressure resistance of the component with the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement, even the refrigerant circuit with a low pressure resistance operates according to the evaporation capability. It becomes possible to use a refrigerant having a high pressure.

Further, the refrigerant which is the working fluid in the refrigerant circuit in which the compressor, the condenser, the throttling means, and the evaporator are sequentially connected by piping is replaced with a higher-pressure refrigerant, and the replaced refrigerant causes the refrigerant in the refrigerant circuit. Replace the condenser with a condenser whose saturation pressure is less than the pressure resistance of the component with the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement. The condensing capability allows the use of refrigerants with high operating pressures, even with components.

Further, the refrigerant which is the working fluid in the refrigerant circuit in which the compressor, the condenser, the throttle means, and the evaporator are sequentially connected by piping is replaced with a higher-pressure refrigerant, and the replaced refrigerant causes the refrigerant in the refrigerant circuit. Since the evaporator whose capacity can be controlled so that the saturation pressure is equal to or lower than the pressure resistance of the component with the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement is low, the pressure resistance before replacement is low. Even if a component of the refrigerant circuit is included, it is possible to use a refrigerant having a high operating pressure due to the evaporation ability.

Further, the refrigerant which is the working fluid in the refrigerant circuit in which the compressor, the condenser, the throttle means, and the evaporator are sequentially connected by piping is replaced with a higher-pressure refrigerant, and the replaced refrigerant causes the refrigerant in the refrigerant circuit. Since the control means for controlling the pressure so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement is replaced, the refrigerant having a low pressure resistance before replacement is replaced. Since the saturation pressure can be suppressed by the pressure control even if the components of the circuit are included, it is possible to use a refrigerant having a high operating pressure.

Further, by configuring the refrigerant circuit device through any one of the refrigerant circuit replacement methods described above, the product can be made inexpensive and the amount of waste due to the replacement can be reduced.

Further, a refrigerant circuit in which a compressor, a first condenser, a second condenser, a restrictor, and an evaporator are sequentially connected by piping, and a flow of the refrigerant to the second condenser is closed. Opening / closing means, pressure detecting means for detecting the condensing pressure of the first condenser or temperature detecting means for detecting the condensing temperature of the first condenser, and the pressure detected by the pressure detecting means or the temperature detection Since the control means for controlling the opening and closing of the opening and closing means according to the temperature detected by the means is provided, it is possible to use a refrigerant having a high operating pressure due to the condensation ability even in a refrigerant circuit having a low pressure resistance.

Since the second condenser is a water-cooled condenser, the condensation pressure can be greatly reduced.

Further, since the second condenser is a cold heat storage tank, a stable low-temperature heat radiation source can be secured, and the reliability is improved.

Further, since the second condenser has an evaporator of another refrigerant circuit and is capable of exchanging heat with each other, it is possible to adjust the condensing capacity and to perform fine and stable control corresponding to the load. .

Also, a refrigerant circuit in which a compressor, a condenser, a throttle means and a plurality of evaporators arranged in parallel are connected in sequence by a pipe, a pressure detecting means for detecting the condensing pressure of the condenser, When the pressure detected by the pressure detecting means exceeds a predetermined value, control means for lowering the evaporation capacity of a part or all of the plurality of evaporators is provided. Can be reduced, and an effect of suppressing a pressure rise while maintaining operation can be obtained.

The refrigerant used is R22 or R4
R22C or R407C, which is a refrigerant other than 07C and has a saturation pressure at the same temperature.
Even a refrigerant having higher pressure characteristics than any of
It is possible to use the refrigerant with the same pressure resistance as before, and it is possible to use a refrigerant that meets the purpose such as the global warming potential.

A refrigerant circuit in which a plurality of compressors, condensers, throttling means, and evaporators are sequentially connected by pipes, a refrigerant to be used other than R22 and R407C, and a saturation pressure with respect to an arbitrary temperature. Refrigerant R22 or refrigerant R4
In the case of using a refrigerant having a saturation pressure characteristic higher than either one of the compressors, the control means for individually controlling the operation of the plurality of compressors is provided. The operation can be continued without performing.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 1 of the present invention.

FIG. 2 is a control block diagram according to the first embodiment of the present invention.

FIG. 3 is a control flowchart according to the first embodiment of the present invention.

FIG. 4 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 2 of the present invention.

FIG. 5 is a control block diagram according to Embodiment 2 of the present invention.

FIG. 6 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 2 of the present invention.

FIG. 7 is a control flowchart according to Embodiment 2 of the present invention.

FIG. 8 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 2 of the present invention.

FIG. 9 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 3 of the present invention.

FIG. 10 is a control block diagram according to Embodiment 3 of the present invention.

FIG. 11 is a control flowchart according to Embodiment 3 of the present invention.

FIG. 12 is a control flowchart according to Embodiment 3 of the present invention.

FIG. 13 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 4 of the present invention.

FIG. 14 is a control block diagram according to Embodiment 4 of the present invention.

FIG. 15 is a control flowchart according to Embodiment 4 of the present invention.

FIG. 16 is a refrigerant circuit diagram showing an air conditioner according to Embodiment 5 of the present invention.

FIG. 17 is a control block diagram according to Embodiment 5 of the present invention.

FIG. 18 is a control flowchart according to Embodiment 5 of the present invention.

FIG. 19 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 6 of the present invention.

FIG. 20 is a control block diagram according to Embodiment 6 of the present invention.

FIG. 21 is a control flowchart according to Embodiment 6 of the present invention.

[Explanation of symbols]

1 compressor, 1a compressor, 1b compressor, 2a
Heat source unit side main heat exchanger, 2b Heat source unit side auxiliary heat exchanger, 2c auxiliary heat exchanger, 3a Flow control device,
3b flow control device, 4a utilization side heat exchanger, 4b
Use side heat exchanger, 5a remote control, 5b remote control, 7 heat transfer tube, 11-14 solenoid valve, 15 flow control device, 16 four-way valve, 19 operation control unit,
20 pressure sensor, 21 water temperature sensor, 23
Outside air temperature sensor, 24-28 solenoid valve.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F25B 39/04 F25B 39/04 Z

Claims (13)

[Claims] 1. A refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant. A method of controlling a refrigerant circuit, comprising: controlling a condensation capacity so that a saturation pressure is equal to or lower than a pressure resistance of a component having the lowest pressure resistance among components used in a refrigerant circuit used before and after replacement. 2. A refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant. A method of controlling a refrigerant circuit, characterized by controlling an evaporation capacity so that a saturation pressure is equal to or lower than a pressure resistance of a component having the lowest pressure resistance among components in a refrigerant circuit used before and after replacement. 3. A refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant, and the refrigerant in the refrigerant circuit is replaced by the replaced refrigerant. A method of exchanging a refrigerant circuit, wherein the condenser is replaced with a condenser having a capacity whose saturation pressure is equal to or lower than the withstand pressure of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after the replacement. 4. A refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant, and the refrigerant in the refrigerant circuit is replaced by the replaced refrigerant. Replacing the refrigerant circuit with an evaporator whose capacity can be controlled so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after the replacement. Method. 5. A refrigerant, which is a working fluid in a refrigerant circuit in which a compressor, a condenser, a throttle means, and an evaporator are sequentially connected by piping, is replaced with a higher-pressure refrigerant, and the refrigerant in the refrigerant circuit is replaced by the replaced refrigerant. A method for replacing a refrigerant circuit, wherein the control means controls the pressure so that the saturation pressure is equal to or lower than the pressure resistance of the component having the lowest pressure resistance among the components in the refrigerant circuit used before and after replacement. . 6. A refrigerant circuit device configured through the method of replacing a refrigerant circuit according to any one of claims 3 to 5. 7. A compressor, a first condenser, a second condenser,
A refrigerant circuit formed by sequentially connecting a throttle unit and an evaporator by piping, an opening / closing unit for closing the flow of the refrigerant to the second condenser, and a pressure detecting unit for detecting a condensing pressure of the first condenser Alternatively, the temperature control device includes temperature detecting means for detecting a condensation temperature of the first condenser, and control means for controlling opening and closing of the opening and closing means according to the pressure detected by the pressure detecting means or the temperature detected by the temperature detecting means. A refrigerant circuit device. 8. The refrigerant circuit device according to claim 7, wherein the second condenser is a water-cooled condenser. 9. The refrigerant circuit device according to claim 7, wherein the second condenser is a cold heat storage tank. 10. The second condenser having an evaporator of another refrigerant circuit and capable of exchanging heat with each other.
The refrigerant circuit device according to claim 1. 11. A refrigerant circuit in which a compressor, a condenser, a restrictor, and a plurality of evaporators arranged in parallel are sequentially connected by piping, a pressure detector for detecting a condensing pressure of the condenser, A refrigerant circuit device comprising: control means for lowering a part or all of the plurality of evaporators when the pressure detected by the pressure detection means exceeds a predetermined value. 12. The refrigerant used is R22 or R40.
It is a refrigerant other than 7C, and the saturation pressure at the same temperature is
12. A refrigerant having a higher pressure characteristic than either R22 or R407C.
A refrigerant circuit device according to any one of the above. 13. A refrigerant circuit in which a plurality of compressors, condensers, throttling means, and evaporators are sequentially connected by piping, and a refrigerant to be used is other than R22 and R407C, and a saturation pressure at an arbitrary temperature is lower than R22 or R407C. Refrigerant R22 or refrigerant R40
When using a refrigerant having a saturation pressure characteristic higher than that of any one of 7C, control means for individually controlling the operation of the plurality of compressors is provided.