JP3125778B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner which is operated throughout the year irrespective of the outside air temperature. Regarding the harmonic machine.

[0002]

2. Description of the Related Art In recent years, with the spread of mobile communications such as mobile phones, heat generated by electronic devices such as a computer room and a base station (shelter) containing relay electronic devices for mobile communications has been reduced. The area of removal is expanding rapidly, and these locations require year-round cooling.

[0003] In these applications, when the outside air temperature is low, such as in winter or at night, air can be cooled by ventilation. In addition, since the room temperature fluctuates due to the fluctuation of the outside air temperature, stable cooling cannot be performed. Under such conditions, it is possible to use an air conditioner that utilizes natural circulation in which heat is transferred from a room to the outside by a refrigerant by utilizing a temperature difference between the indoor temperature and the outside air temperature. An air conditioner using this natural circulation can significantly reduce annual power consumption compared to an air conditioner using forced circulation using a compressor.

[0004] Here, the operation principle of the cooling operation by natural circulation will be described with reference to FIG. FIG. 19 is a configuration diagram showing a cooling device as an air conditioner utilizing natural circulation. In the drawing, reference numeral 2 denotes a condenser, 3 denotes an outdoor fan, 5 denotes an outdoor unit, 6 denotes a liquid pipe, 7 denotes an evaporator, 8 Denotes an indoor fan, 9 denotes an indoor unit arranged in the space to be air-conditioned, and 10 denotes a gas pipe. When the condenser 2 is disposed at a position higher than the evaporator 7, the liquid refrigerant condensed in the condenser 2 descends in the liquid pipe 6 by gravity and flows into the evaporator 7. The liquid refrigerant that has flowed into the evaporator 7 evaporates by receiving a heat load in a space to be air-conditioned, for example, a room, and then moves up the gas pipe 10 and returns to the condenser 2 to form a cycle.

[0005] As described above, the cooling operation by natural circulation uses the difference in density between the liquid refrigerant and the gas refrigerant in the positional difference between the indoor unit 9 and the outdoor unit 5 as the driving force for circulating the refrigerant. , The sum of the pressure losses in the refrigerant passages such as the condenser 2, the evaporator 7, the liquid pipe 6, the gas pipe 10, and the on-off valve in the refrigerant circuit is equal to the pressure rise due to the height of the liquid column in the liquid pipe 6. Holds if.

FIG. 20 shows a pressure-enthalpy diagram in a cooling operation cycle by forced circulation operation using a general compressor. In FIG. 20, the horizontal axis is enthalpy and the vertical axis is pressure. FIG. 21 shows a pressure-enthalpy diagram in a cycle of natural circulation operation without using a compressor in comparison with this. In FIG. 21 as well, the horizontal axis is enthalpy and the vertical axis is pressure, and the cooling operation cycle by forced circulation operation has a configuration in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected by piping. In FIG. 20, reference numeral 34 denotes a decrease in enthalpy and a pressure drop in the condenser;
5 is a pressure drop by the expansion valve, 36 is an increase in enthalpy and pressure drop in the evaporator, 37 is an increase in enthalpy and pressure rise by the compressor, 38 is a refrigerant pressure corresponding to the room temperature, and 39 is a refrigerant pressure corresponding to the outside air temperature. Refrigerant pressure. The arrows in the figure indicate the flow direction of the refrigerant. In FIG. 21, reference numeral 40 denotes an increase in enthalpy and a pressure drop in the evaporator;
41 represents a pressure drop in the gas pipe, 42 represents a decrease in enthalpy and a pressure drop in the condenser, and 43 represents a pressure rise obtained by subtracting a pressure drop in the liquid pipe from a pressure rise due to a height difference in the liquid pipe. Comparing FIG. 20 with FIG. 21, the enthalpy change amount in the evaporator and the enthalpy change amount in the condenser in the cycle of the cooling operation by the natural circulation are smaller than those in the cooling operation cycle by the forced circulation using the compressor. It has a feature that the flow of the refrigerant is almost equal and the flow is opposite.

As an example of an air conditioner utilizing natural circulation, there is a cooling operation by forced circulation using a compressor (hereinafter abbreviated as forced circulation operation) as disclosed in Japanese Patent Application Laid-Open No. 9-250779. There is one that uses cooling operation by natural circulation (hereinafter, abbreviated as natural circulation operation) in combination.
FIG. 22 is a configuration diagram showing a conventional air conditioner having a forced circulation operation and a natural circulation operation. In the figure, 1 is a compressor, 2 is a condenser, 3 is an outdoor fan, 5 is an outdoor unit, 6 is a liquid pipe, 7 is an evaporator, 9 is an indoor unit, 10 is a gas pipe, 12
Is a compressor bypass pipe for bypassing the compressor 1, 14 is an accumulator, 13, 22, 44 and 45 are on-off valves respectively, 46 is an expansion valve, and 23 is a bypass pipe for bypassing the expansion valve 46 and the on-off valve 45.

In this air conditioner, four on-off valves 13, 44, 2 for bypassing the compressor 1 and the expansion valve 46 are provided.
2, 45 are provided. The condenser 2 is arranged at a position higher than the evaporator 7. When the outside air temperature is lower than the room temperature, the on-off valves 44 and 22 are opened, and the on-off valves 13 and 4 are opened.
5 is closed to constitute a cycle of natural circulation operation. That is, the liquid refrigerant condensed in the condenser 2 descends by gravity in the liquid pipe 6 and flows into the evaporator 7 through the on-off valve 22 of the expansion valve bypass pipe 23. The liquid refrigerant that has flowed into the evaporator 7 evaporates under the heat load in the room, and then ascends the gas pipe 10 and returns to the condenser 2 through the on-off valve 44 of the compressor bypass pipe 12 to form a cycle. .

When the outside air temperature is higher than the room temperature, the on-off valves 13 and 45 are opened, and the on-off valves 44 and 22 are closed, and the compressor 1 is operated in a forced circulation cycle. That is, the refrigerant gas in the pipe is adiabatically compressed by the compressor 1 to be in an overheated state, and is radiated and liquefied to outside air by the condenser 2 to be a refrigerant liquid. Thereafter, the high-pressure refrigerant liquid is supplied to the liquid pipe 6.
The air passes through the on-off valve 45 and is decompressed by the expansion valve 46 to become low-temperature low-pressure wet steam in a gas-liquid mixed state. further,
The refrigerant absorbs heat of vaporization in the evaporator 7 to become a refrigerant gas, and returns to the compressor 1 through the gas pipe 10 and the accumulator 14. At this time, in the accumulator 14, surplus refrigerant is accumulated in the forced circulation operation.

As described above, this air conditioner is provided with the forced circulation operation and the natural circulation operation, and is switched in accordance with the outside air temperature and the indoor temperature. Therefore, the annual power consumption can be significantly reduced. Although not shown here, an indoor fan is often provided also on the indoor unit 9 side, but even in a device having an outdoor fan and an indoor fan, annual power consumption is significantly reduced.

Here, due to the difference in the state of the refrigerant in the refrigerant circuit, the required amount of refrigerant in the natural circulation operation is generally larger than that in the forced circulation operation. Therefore, in the conventional air conditioner, the condenser 2
In order to absorb the difference in the amount of refrigerant between the natural circulation operation and the forced circulation operation, for example, the expansion valve 46 provided near the outlet of the air conditioner is disposed on the indoor unit side. However, in practice, when the operation is switched from the forced circulation operation to the natural circulation operation, the surplus refrigerant accumulated in the accumulator 14 during the forced circulation operation is recovered to the condenser 2 side before the natural circulation operation. It was necessary to perform a refrigerant recovery operation. Therefore, in the conventional air conditioner using both the forced circulation operation and the natural circulation operation, the four on-off valves 44, 13, 22, and 45 and the connection thereof are used for switching the refrigerant circuit of both operations and recovering the refrigerant at the time of operation switching. Was equipped with plumbing.

In general, the temperature in a computer room or a base station (shelter) in which relay electronic equipment for mobile communication is stored is 2 degrees.
The temperature is controlled in the range of about 5 to 35 ° C., but when the outside air temperature is low, such as in winter, the cooling capacity obtained by natural circulation operation increases, so that the compressor 1 is stopped for a long time,
As time elapses, the temperature of the compressor 1 decreases. When the temperature of the compressor 1 decreases, the refrigerant gas gradually condenses to the compressor 1 from the cycle of the natural circulation operation, so that not only the amount of refrigerant required for the natural circulation operation is not secured, but also the compressor 1 is started. Occasionally, there is a possibility that a phenomenon that liquid compression occurs and leads to breakage may occur.

[0013]

In a conventional air conditioner using both forced circulation operation and natural circulation operation, four open / close valves 44, 13 for switching the refrigerant circuit of both operations and recovering the refrigerant at the time of operation switching. 22, 45 and piping connecting them were provided. Of these on-off valves, the on-off valves 22 and 44 serving as refrigerant passages for the natural circulation operation use expensive large-diameter on-off valves in order to reduce pressure loss. There is a problem that the system becomes expensive as compared with the conventional system. Further, the presence of a large number of on-off valves complicates the refrigerant circuit, and there is a problem in that it is difficult to store the refrigerant in the outdoor unit 5 due to space restrictions in the outdoor unit 5.

Further, during the forced circulation operation, since the surplus refrigerant is accumulated in the accumulator 14, at the time of switching to the natural circulation operation, it is necessary to perform a refrigerant recovery operation for recovering the surplus refrigerant to the condenser 2 side. However, when the refrigerant recovery operation is performed with the expansion valve 46 completely closed, the suction pressure of the compressor 1 sharply drops, so that the refrigerant liquid sucked into the compressor 1 foams and the refrigerating machine oil discharges gas. At the same time, the oil flows out into the refrigerant circuit, and the amount of refrigerating machine oil in the compressor decreases, which may result in burnout due to poor lubrication. In addition, in the refrigerant recovery operation, particularly when the temperature of the discharged superheated gas is low, such as when the outside air temperature is low, it takes a lot of time to evaporate the refrigerant liquid in the accumulator 14, and thus unnecessary forced circulation is performed. There is a problem that the operation is lengthened and the power consumption reduction effect is reduced. In addition, there is a problem that the refrigerating machine oil flowing out into the refrigerant circuit causes an increase in pressure loss and lowers the cooling capacity of natural circulation operation.

When the outside air temperature decreases in winter, for example, the cooling capacity obtained by the natural circulation operation increases, so that the compressor 1 is stopped for a long time, and the temperature of the compressor 1 increases with the lapse of time. Drops. In such a case, since the refrigerant gas is gradually condensed from the natural circulation circuit to the compressor 1, not only the amount of refrigerant required for the natural circulation operation is not ensured, but also liquid compression occurs at the time of starting the compressor 1, resulting in breakage. Could be reached.

Further, when the flow direction of the refrigerant in the condenser 2 is configured from the bottom to the top, or in the connecting pipe between the outlet of the condenser 2 and the liquid pipe 6, a rising pipe from the bottom is provided. If present, there is a problem that the condensed refrigerant liquid stays in the middle of the heat transfer pipe and the connection pipe in the condenser 2, and the natural circulation operation becomes unstable, so that a stable cooling capacity cannot be obtained.

The present invention has been made to solve the above-mentioned conventional problems, and has a forced circulation operation and a natural circulation operation. The number of on-off valves required for switching to the refrigerant circuit in each cycle is provided. It is an object of the present invention to obtain an air conditioner having a refrigerant circuit having a simple configuration by reducing the temperature. Another object of the present invention is to provide an air conditioner that can smoothly switch operation without rapidly reducing the suction pressure of the compressor 1 when recovering the refrigerant.
Another object of the present invention is to provide an air conditioner that can smoothly perform operation switching in a shorter time without suddenly lowering the suction pressure of the compressor 1 when recovering the refrigerant. In addition, the air conditioner includes a forced circulation operation and a natural circulation operation, and prevents the refrigerant gas from flowing into the compressor 1 even when the compressor 1 is in a stopped state for a long period of time. The purpose is to get a chance. It is another object of the present invention to provide an air conditioner that can prevent the condensed refrigerant liquid from staying in the middle of a heat transfer pipe or a connection pipe in the condenser 2.

[0018]

An air conditioner according to the present invention comprises a refrigeration cycle in which a compressor, a condenser, an electronic expansion valve capable of controlling the opening of a valve, and an evaporator are sequentially connected by piping. The outlet of the evaporator and the inlet of the condenser are first
A compressor bypass pipe connected via an on-off valve,
The first on-off valve is closed, the compressor, the condenser, the electronic expansion valve, and the evaporator are sequentially connected to each other, and the forced circulation operation in which the compressor is in an operating state, and the first on-off valve is opened. The condenser, the electronic expansion valve, and the evaporator are sequentially connected to bypass the compressor, and can be switched between a natural circulation operation in which the compressor is stopped and a refrigerant during the forced circulation operation. Is controlled so as to reduce the pressure loss during the natural circulation operation and to increase the opening of the electronic expansion valve as compared to the forced circulation operation.

The first on-off valve of the air conditioner according to the present invention is a check valve that opens the flow of the refrigerant from the outlet of the evaporator to the inlet of the condenser and closes the flow in the opposite direction. Things.

In the air conditioner according to the present invention, an accumulator is provided in a pipe between an inlet of the compressor bypass pipe and an inlet of the compressor.

In the air conditioner according to the present invention, a second on-off valve is provided in a pipe between an inlet of the compressor bypass pipe and an inlet of the accumulator.

Further, the air conditioner according to the present invention is provided with heating means for heating the refrigerant in the accumulator.

The diameter of the gas pipe, which is a pipe from the outlet of the evaporator to the inlet of the condenser, is 1.5 times smaller than the diameter of the liquid pipe, which is a pipe from the outlet of the condenser to the inlet of the evaporator.
It is about two times larger.

In the air conditioner according to the present invention, the compressor, the condenser and the electronic expansion valve are arranged in the outdoor unit, and the evaporator is arranged in the indoor unit.

In the air conditioner according to the present invention, the high-pressure pipe from the outlet of the compressor to the inlet of the condenser and the low-pressure pipe from the outlet of the electronic expansion valve to the inlet of the compressor are provided. The fourth on-off valve is connected when the operation is switched from the forced circulation operation to the natural circulation operation by a bypass pipe via a four-on-off valve.

In the air conditioner according to the present invention, the high-pressure pipe from the outlet of the compressor to the inlet of the condenser is connected to the accumulator by a bypass pipe via a fourth on-off valve.

In the air conditioner according to the present invention, a mechanism for adjusting the amount of splash of the stored refrigerant is provided in the accumulator.

Further, the method for recovering refrigerant in an air conditioner according to the present invention includes a step of suppressing a splash amount of the refrigerant stored in the accumulator.

In the air conditioner according to the present invention, a liquid receiver for storing a refrigerant liquid is provided in a pipe between an outlet of the condenser and an inlet of the electronic expansion valve.

In the air conditioner according to the present invention, an oil separator for separating refrigeration oil is provided in a pipe between the outlet of the compressor and the inlet of the condenser.

In the air conditioner according to the present invention, the outlet of the condenser and the inlet of the evaporator are connected by an expansion valve bypass pipe via a fifth on-off valve.

In the air conditioner according to the present invention, a third on-off valve is provided in a pipe between an outlet of the compressor and an outlet of the compressor bypass pipe, the first on-off valve is closed, and the third on-off valve is closed. It is possible to switch between a forced circulation operation in which the valve is opened and the compressor is in an operating state and a natural circulation operation in which the first on-off valve is opened and the third on-off valve is closed and the compressor is stopped. Things.

The third on-off valve of the air conditioner according to the present invention is a check valve for opening the flow of the refrigerant from the outlet of the compressor to the outlet of the compressor bypass pipe and closing the flow in the opposite direction. It is what it was.

The air conditioner according to the present invention is configured such that the refrigerant flowing into the condenser flows downward from above in the condenser.

In the air conditioner according to the present invention, the refrigerant pipe in the condenser is vertically divided into a plurality of refrigerant flow paths, and each of the branched refrigerants flows through the refrigerant flow path from above to below. The condenser is configured to join at an outlet of the condenser, and a subcooling unit is provided at a lower part in the condenser.

Further, in the air conditioner according to the present invention, the refrigerant pipe in the condenser is vertically divided into a plurality of refrigerant flow paths, and each of the branched refrigerants flows through the refrigerant flow path from above to below. The refrigerant flow path is configured to join at the outlet of the condenser, and the length of the upper refrigerant flow path is longer than the length of the lower refrigerant flow path.

The air conditioner according to the present invention is configured such that the refrigerant flowing into the evaporator flows upward from below in the evaporator.

In the air conditioner according to the present invention, the pipe diameter from the outlet of the evaporator to the inlet of the condenser is larger than the pipe diameter from the outlet of the condenser to the inlet of the evaporator. Things.

In the air conditioner according to the present invention, the heat transfer area of the evaporator is larger than the heat transfer area of the condenser.

In the air conditioner according to the present invention, the height of the outlet of the refrigerant pipe of the condenser is 0.5 m or more and 2 m or less higher than the height of the outlet of the refrigerant pipe of the evaporator. Things.

In the air conditioner according to the present invention, the connection between the outlet of the refrigerant pipe of the condenser and the liquid pipe constituting the refrigeration cycle is disposed below the bottom of the container of the condenser. It is.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 1 of the present invention. FIG. 1 is a configuration diagram showing an air conditioner according to the present embodiment. In the figure, 1 is a compressor, 2 is a condenser, 3 is an outdoor fan, 4 is an expansion valve, for example, an electronic expansion valve, 5 is an outdoor unit, 6 is a liquid pipe, 7 is an evaporator, 8 is an indoor fan, 9 Is an indoor unit, 10 is a gas pipe, 11 is an on-off valve (first on-off valve), for example, a check valve, and 12 is a compressor bypass pipe. In the figure, arrows indicate the flow direction of the refrigerant.

The electronic expansion valve 4 is an expansion valve that can be controlled from the outside so that its opening can be set by an electric current to be supplied. In this embodiment, the opening degree differs between the forced circulation operation and the natural circulation operation. Set and switch. The gas pipe 10 is a pipe from the outlet of the evaporator 7 to the inlet of the condenser 2, and the liquid pipe 6 is a pipe from the outlet of the condenser 2 to the inlet of the evaporator 7. The diameter of the gas pipe 10 is set to about 1.5 to 2 times the diameter of the liquid pipe 6,
Is configured to be thicker. In this embodiment, a refrigerant such as R22 or R-407C is used as a refrigerant, a scroll compressor is used as a compressor, and an alkylbenzene oil or an ester oil is used as a refrigerating machine oil. However, the present invention is not limited to this, and other refrigerants, other compressors, and other refrigerating machine oils may be used.

As shown in FIG. 1, the air conditioner includes an outdoor unit 5 and an indoor unit 9, a liquid pipe 6 for connecting them, and a gas pipe 10. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. The electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid exiting the compressor 2 into two-phase wet steam, and the compressor bypass via the check valve 11 for bypassing the compressor 1 during natural circulation operation It is composed of a pipe 12. Further, the indoor unit 9 evaporates the wet steam flowing from the liquid pipe 6 by an air conditioning load in the room, which is a space to be air-conditioned, to form an evaporator 7 as a refrigerant gas. Indoor fan 8 for blowing air
It is composed of The condenser 2 of the outdoor unit 5 is arranged at a position higher than the evaporator 7 of the indoor unit 9, and here, for example, is arranged with a height difference of about 1.2 m.

This air conditioner is used, for example, in places where cooling is required throughout the year. When the indoor temperature is lower than the outside air temperature, the air conditioner performs a forced circulation operation with the compressor 1 in an operating state, and the indoor temperature becomes lower than the outside air temperature. High, compressor 1
Is stopped, and natural circulation operation using the cold of outside air is performed. Here, first, the forced circulation operation will be described.
The opening degree of the electronic expansion valve 4 is set to an appropriate opening degree for reducing the refrigerant liquid flowing out of the condenser 2 to two-phase wet steam, for example, an electronic expansion valve 4 having a full opening of 2000 pulse.
Is used, an opening degree of about 15%, for example, 300p
When the compressor 1 is set to ulse and the compressor 1 is operated, the check valve 11 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 1 and a cycle of the forced circulation operation is formed. That is, the refrigerant gas in the pipe is adiabatically compressed by the compressor 1 to be in an overheated state, and is radiated to the outside air by the condenser 2 to be liquefied to be a refrigerant liquid. Thereafter, the high-pressure refrigerant liquid passes through the electronic expansion valve 4 and is decompressed by the electronic expansion valve 4 to become low-temperature, low-pressure wet steam in a gas-liquid mixed state. Further, the refrigerant passes through the liquid pipe 6 and absorbs the heat of vaporization in the evaporator 7 to become a refrigerant gas.
And returns to the compressor 1.

Next, the natural circulation operation when the outside air temperature is lower than the room temperature will be described. When the opening of the electronic expansion valve 4 is fully opened to reduce the pressure loss in the refrigerant circuit, the check valve 11 is opened by the flow of the refrigerant, and a natural circulation operation cycle is formed. Then, the liquid refrigerant condensed in the condenser 2 descends in the liquid pipe 6 by gravity and flows into the evaporator 7. The liquid refrigerant that has flowed into the evaporator 7 evaporates by receiving a heat load in the room, and then ascends the gas pipe 10 and returns to the condenser 2 through the check valve 11 of the compressor bypass pipe 12.
Here, the refrigerant tends to flow also in the flow path passing through the compressor 1, but the flow resistance inside the compressor 1 is reduced by the compressor bypass pipe 12.
, The flow rate of the refrigerant passing through the compressor 1 becomes negligibly smaller than the flow rate of the refrigerant passing through the compressor bypass pipe 12.

As described above, the air conditioner is provided with the forced circulation operation and the natural circulation operation, and is configured to switch according to the outside air temperature and the indoor temperature. Because only input of
The annual power consumption can be significantly reduced. In this air conditioner, the opening degree is externally controlled by controlling two functions, ie, the pressure reducing function of the expansion valve 46 and the bypass function of the expansion valve 46 of the on-off valve 22 in the conventional example of FIG. This is realized by one possible electronic expansion valve 4, and the three on-off valves 13, 22, and 45 in the conventional device are not required, so that an inexpensive and simple device can be configured. Further, since the number of on-off valves required for switching between the natural circulation operation and the forced circulation operation can be reduced, all the components of the refrigerant circuit can be easily housed in the outdoor unit 5.

Also, the check valve 11 provided in the compressor bypass circuit 12 uses an electromagnetic on-off valve or the like, and is operated in the same manner as described above even when the check valve 11 is opened during natural circulation operation and closed during forced circulation operation. It works. However, if the check valve 11 that opens the flow of the refrigerant from the outlet of the evaporator 7 to the inlet of the condenser 2 and closes the flow in the opposite direction is used as in the above embodiment, the natural circulation operation is performed. It is not necessary to open and close according to the forced circulation operation, and the refrigerant circuit can be easily changed. That is, in the forced circulation operation, the check valve 11 is automatically closed due to the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and when switching to the natural circulation operation, the opening degree of the electronic expansion valve 4 is changed. When the compressor is fully opened and the compressor 1 is stopped, the refrigerant naturally circulates in the refrigerant circuit, the pressure applied to both sides of the check valve 11 is reversed, and the check valve 11 is automatically opened.

In general, the gas flow rate is larger than the liquid flow rate at the same pipe diameter and the same refrigerant flow rate, so that the pressure loss of the gas pipe 10 is larger than the pressure loss of the liquid pipe 6. In the natural circulation operation, the flow rate of the refrigerant is determined so that the pressure rise due to the height difference is equal to the pressure loss in the refrigerant circuit. Therefore, the increase in the pressure loss in the refrigerant circuit directly affects the decrease in the cooling capacity. Therefore, reducing the pressure loss in the refrigerant circuit and increasing the flow rate of the refrigerant promotes an increase in the cooling capacity. In the air conditioner according to the present embodiment, the pipe diameter of the gas pipe 10, which is a pipe from the outlet of the evaporator 7 to the inlet of the condenser 2, is a pipe from the outlet of the condenser 2 to the inlet of the evaporator 7. Since it is configured to be, for example, about 1.5 to 2 times larger than the pipe diameter of the liquid pipe 6, the pressure loss in the refrigerant circuit can be reduced, and the flow rate of the refrigerant can be increased. Therefore, it is possible to suppress a decrease in the cooling capacity of the natural circulation operation due to an increase in the pressure loss. In the above, the gas pipe 1 is compared with the liquid pipe 6.
The pipe diameter of 0 is configured to be, for example, about 1.5 to 2 times larger, but the size is not limited to this. If the gas pipe 10 is made thicker than the liquid pipe 6, it is possible to prevent a decrease in cooling capacity in natural circulation operation, although the effect varies depending on the degree.

Embodiment 2 Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 2 of the present invention. FIG. 2 is a configuration diagram showing the air conditioner according to the present embodiment. In the figure, reference numeral 14 denotes an accumulator for preventing the liquid from returning to the compressor 1 in the event of a transient phenomenon or overfilling of the refrigerant, between the inlet of the compressor bypass pipe 12 and the inlet of the compressor 1. It is provided in the piping of. 13
Is the inlet of the compressor bypass pipe 12 and the accumulator 1
4 is provided in the pipe between the inlet and the accumulator 1
On-off valve (second on-off valve) for preventing the refrigerant from flowing into 4 (1)
Reference numeral 6 denotes an on-off valve (third on-off valve) provided in a pipe between an outlet of the compressor 1 and an outlet of the compressor bypass pipe 12, and for example, an outlet from the compressor 1 to an outlet of the compressor bypass pipe 12. This is a check valve that opens the flow of the refrigerant to the section and closes the flow in the opposite direction. The same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the arrows in the figure indicate the flow direction of the refrigerant. As in the first embodiment, an outdoor unit 5 and an indoor unit 9, and a liquid pipe 6 and a gas pipe 10 for connecting them are configured. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. Electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid exiting the compressor 2 to produce two-phase wet vapor, and prevents liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling. , An on-off valve 13 for bypassing the compressor 1 and the accumulator 14 during natural circulation operation, a compressor bypass pipe 12 via a check valve 11, and a compressor bypass pipe 12 flowing during natural circulation operation. Check valve 1 for preventing refrigerant from flowing into compressor 1
6. Further, the indoor unit 5 evaporates the wet steam flowing from the liquid pipe 6 by the air conditioning load in the room, which is the space to be air-conditioned, to form the evaporator 7 as the refrigerant gas, and forcibly applies the indoor air to the outer surface of the evaporator 7. It comprises an indoor fan 8 for blowing air.

In this air conditioner, when the forced circulation operation is performed, the on-off valve 13 is opened and the opening of the electronic expansion valve 4 is
The compressor 1 is operated at an appropriate opening for reducing the pressure of the refrigerant liquid flowing out of the condenser 2 to two-phase wet steam, for example, about 15% of the full opening. In such an operating state, the check valve 11 is automatically closed due to the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and the check valve 16 is automatically opened to perform the cycle of the forced circulation operation. Is formed.

When the natural circulation operation is performed, the compressor 1
When the valve is stopped, the on-off valve 13 is closed almost at the same time, and when the opening of the electronic expansion valve 4 is fully opened, the check valve 11 is opened by the flow of the refrigerant, and a natural circulation operation cycle is formed. When the forced circulation operation is performed again, first, the on-off valve 13 is closed, and the compressor 1 is operated almost at the same time as the opening degree of the electronic expansion valve 4 is reduced.

In this air conditioner, two functions, ie, the pressure reducing function of the expansion valve 46 in the conventional example of FIG. 22 and the bypass function of the expansion valve 46 of the on-off valve 22, are provided.
The opening is realized by one electronic expansion valve 4 that can be controlled from the outside, and the two valves 22 and 45 in the conventional device are not required, so that an inexpensive and simple device can be configured. Further, since the number of on-off valves required for switching between the natural circulation operation and the forced circulation operation can be reduced, all the components of the refrigerant circuit can be easily housed in the outdoor unit 5.

The check valve 11 provided in the compressor bypass circuit 12 may be an electromagnetic on-off valve or the like.
When the check valve is configured to open the flow of the refrigerant from the outlet to the inlet of the condenser 2 and close the flow in the opposite direction, it is not necessary to open and close according to the natural circulation operation and the forced circulation operation. Changes to the refrigerant circuit can be made.

By the way, due to the difference in the state of the refrigerant in the refrigerant circuit, the required amount of refrigerant is larger in the natural circulation operation than in the forced circulation operation. In the present embodiment, the compressor bypass pipe 12
Since the accumulator 14 is provided in the pipe between the inlet of the compressor 1 and the inlet of the compressor 1, the excess refrigerant generated during the forced circulation operation can be absorbed. Further, it is necessary to prevent the refrigerant from staying in the refrigerant circuit during natural circulation operation as much as possible. Since the inside of the fuel cell 14 has a low temperature and a low pressure, the refrigerant attempts to flow into the accumulator 14 after the operation is switched to the natural circulation operation. Therefore, in the air conditioner of the present embodiment, the on-off valve 13 is provided in the pipe between the inlet of the compressor bypass pipe 12 and the inlet of the accumulator 14. For this reason, if the on-off valve 13 is closed at the time of switching from the forced circulation operation to the natural circulation operation, the refrigerant can be prevented from flowing into the accumulator 14, and the amount of refrigerant required for the natural circulation operation can be secured. A stable cooling capacity is always obtained.

In this embodiment, a check valve 16 is provided in a pipe between the outlet of the compressor 1 and the outlet of the compressor bypass pipe 12. Normally, immediately after the operation switching from the forced circulation operation to the natural circulation operation, the temperature of the compressor 1 is maintained higher than the refrigerant saturation temperature during the natural circulation operation due to the heat capacity of the compressor 1 itself. The refrigerant does not flow from the outlet to the outlet of the compressor 1. However, when the outside air temperature is low, such as in winter, the cooling capacity obtained by the natural circulation operation increases, so that the compressor 1 is stopped for a long time, and the temperature of the compressor 1 decreases over time. In such a case, since the refrigerant is gradually condensed from the refrigerant circuit of the natural circulation to the compressor 1, not only the amount of refrigerant required for the natural circulation operation is not ensured, but also the compressor 1
The liquid may be compressed at the time of startup and may be damaged. In the air conditioner of the present embodiment, a check valve 16 is provided between the outlet of the compressor 1 and the outlet of the compressor bypass pipe 12.
In the natural circulation operation, most of the refrigerant flows through the compressor bypass pipe 12, so that a pressure difference is generated between both ends of the check valve 16, and the check valve 16 is automatically closed. For this reason, even if the compressor 1 is in a stopped state for a long time, it is possible to prevent the refrigerant from flowing into the compressor 1 and condensing it, to secure the amount of refrigerant necessary for natural circulation operation, and to improve the reliability of the compressor 1. Performance can be improved.

The same effect as described above can be obtained even when the check valve 16 is operated by using an electromagnetic on-off valve or the like so as to be opened in forced circulation operation and closed in natural circulation operation. However, when a check valve that opens the flow of the refrigerant from the outlet of the compressor 1 to the outlet of the compressor bypass pipe 12 and closes the flow in the opposite direction is used as in the above embodiment, the pressure on both sides is reduced. Since the opening and closing are automatically performed according to the difference, there is no need to perform opening and closing according to the natural circulation operation and the forced circulation operation, and the condensation of the refrigerant into the compressor 1 can be reliably shut off during the natural circulation operation.

The on-off valve 16 may be provided in a pipe between the outlet of the compressor 1 and the outlet of the compressor bypass pipe 12 in the air conditioner shown in FIG. Also in this configuration, similarly to the above, it is possible to prevent the refrigerant from flowing into the compressor 1 and condense, secure the amount of refrigerant required for natural circulation operation, and improve the reliability of the compressor 1.

Embodiment 3 Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 3 of the present invention. FIG. 3 is a configuration diagram showing the air conditioner according to the present embodiment. In the drawing, reference numeral 15 denotes a heating means for heating the refrigerant in the accumulator, for example, a heater, and the same reference numerals as those in FIG. In the figure, arrows indicate the flow direction of the refrigerant. As in the first embodiment, an outdoor unit 5 and an indoor unit 9, and a liquid pipe 6 and a gas pipe 10 for connecting them are configured. Outdoor unit 5
A compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser 2. An electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid into wet vapor in a two-phase state, and an accumulator 14 for preventing the liquid from returning to the compressor 1 in the event of a transient phenomenon or overfilling of the refrigerant. The compressor includes a compressor bypass pipe 12 through a check valve 11 for bypassing the compressor 1 and the accumulator 14 during the natural circulation operation, and a heater 15 for heating and evaporating excess refrigerant in the accumulator 14. Further, the indoor unit 5 evaporates the wet steam flowing from the liquid pipe 6 by the air conditioning load in the room, which is the space to be air-conditioned, to form the evaporator 7 as the refrigerant gas, and forcibly applies the indoor air to the outer surface of the evaporator 7. It comprises an indoor fan 8 for blowing air.

In this air conditioner, when the forced circulation operation is performed, the opening degree of the electronic expansion valve 4 is set to an appropriate value for reducing the refrigerant liquid flowing out of the condenser 2 to two-phase wet steam. The compressor 1 is set at an opening degree, for example, about 15% of the full opening.
Is operated, the check valve 11 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and a cycle of the forced circulation operation is formed. When performing natural circulation operation, the compressor 1
Is stopped and the opening of the electronic expansion valve 4 is fully opened, the check valve 11 is opened by the flow of the refrigerant, and a cycle of natural circulation operation is formed.

As described in the second embodiment, in the natural circulation operation, the required amount of refrigerant is larger than in the forced circulation operation. There is a need. However, when the accumulator 14 is installed in the outdoor unit 5, the refrigerant flows into the accumulator 14 after the operation is switched from the forced circulation to the natural circulation operation. Therefore, in the present embodiment, energization of the heater 15 is started at the same time when the compressor 1 is stopped, so that the temperature of the accumulator 14 is prevented from lowering. In this case, the refrigerant flows into the accumulator 14 immediately after the switching,
When the refrigerant liquid staying in the accumulator 14 is heated by the heater 15, the refrigerant liquid evaporates to become a refrigerant gas,
It is returned to the refrigerant circuit of natural circulation operation mainly through the inlet pipe of the accumulator 14.

As described above, in the present embodiment, the heater 15 for heating and evaporating the refrigerant liquid in the accumulator 14 is provided, and it is possible to prevent the refrigerant from flowing from the gas pipe 10 to the accumulator 14 during the natural circulation operation. The amount of refrigerant required for circulation operation can be secured. Further, the on-off valve 13 for preventing the refrigerant from staying in the accumulator 14 shown in FIG.

Further, the input electric energy of the heater 15 is sufficient to maintain the temperature of the accumulator 14 at or above the refrigerant saturation temperature during the natural circulation operation, and is smaller than the input electric energy of the compressor 1 required for the refrigerant recovery operation. Because it is smaller, annual power consumption can be reduced.

Even if the input power of the heater 15 is given a fixed amount at the same time when the compressor 1 is stopped, a temperature sensor or a pressure sensor is provided in the piping section of the inlet / outlet of the accumulator 14 and based on the detected value. It may calculate input power and energization time. Further, the amount of the refrigerant liquid in the accumulator 14 may be detected to turn ON / OFF the power supply to the heater 15. In addition, always heater 1
5, the temperature of the accumulator 14 may be kept high. In this case, although the power consumption by the heater 15 increases to some extent, the refrigerant liquid does not stay in the accumulator 14 and the refrigerant recovery operation becomes unnecessary, so that the power consumption of the compressor required for the refrigerant recovery operation can be reduced. As a whole, annual power consumption can be reduced.

Embodiment 4 Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 4 of the present invention. FIG. 4 is a configuration diagram showing the air conditioner according to the present embodiment. In the figure, reference numeral 17 denotes a bypass pipe via an on-off valve (fourth on-off valve) 18 for connecting the high-pressure pipe at the outlet of the compressor 1 and the low-pressure pipe at the inlet of the accumulator 14; The same or corresponding parts are shown. In the figure, arrows indicate the flow direction of the refrigerant. As in the first embodiment, the air conditioner according to the present embodiment includes an outdoor unit 5
And an indoor unit 9 and a liquid pipe 6 and a gas pipe 10 for connecting them. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. An electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid that has exited 2 and turns it into wet vapor in a two-phase state, in order to prevent the liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling. Accumulator 14, an open / close valve 13 for bypassing the compressor 1 and the accumulator 14 during natural circulation operation, a compressor bypass pipe 12 via a check valve 11, and preventing refrigerant from flowing into the compressor 1 during natural circulation operation And a bypass pipe 17 via an on-off valve 18 connecting the high-pressure pipe at the outlet of the compressor 1 and the low-pressure pipe at the inlet of the accumulator 14. The indoor unit 9 includes an evaporator 7 for evaporating wet steam flowing from the liquid pipe 6 by an air conditioning load, and an indoor fan 8.
It is composed of

FIG. 5 is an experimental result showing a change in cooling capacity when the amount of refrigerant charged is changed in natural circulation operation. The horizontal axis represents the ratio of the amount of refrigerant in natural circulation operation to the appropriate amount of refrigerant in forced circulation operation. The vertical axis indicates the cooling capacity. From FIG.
It can be seen that in order to maximize the cooling capacity of the natural circulation operation, it is necessary to charge about twice the amount of the refrigerant as in the forced circulation operation. Therefore, when the refrigerant amount is such that the cooling capacity of the natural circulation operation is maximized, the surplus refrigerant is accumulated in the accumulator 14 at the time of the forced circulation operation as described above, and this surplus refrigerant is used at the time of operation switching for the natural circulation operation. It is necessary to perform a refrigerant recovery operation for returning to the refrigerant circuit.

As a refrigerant recovery operation, there is a method in which the opening degree of the electronic expansion valve 4 is fully closed to perform a forced circulation operation. However, in this method, since the suction pressure of the compressor 1 drops rapidly,
The refrigerant liquid sucked into the compressor 1 foams, and the refrigerating machine oil flows out into the refrigerant circuit together with the discharge gas, so that the refrigerating machine oil amount in the compressor 1 decreases, and there is a possibility that the lubrication failure causes burnout due to poor lubrication. In particular, in the case of a scroll compressor, the amount of oil supplied to a sliding portion is reduced due to a decrease in suction pressure and a bubbling of a refrigerant liquid inside the compressor 1, and the sliding portion is thermally deformed due to a rise in temperature, leading to breakage. Problems arise. In addition, the refrigerating machine oil flowing into the refrigerant circuit causes an increase in pressure loss, which causes a phenomenon that the cooling capacity of natural circulation operation is reduced. In the present embodiment, the reliability during the refrigerant recovery operation as described above and the cooling capacity during the natural circulation operation are improved.

FIG. 6 is a flowchart showing a procedure for switching operation from forced circulation operation to natural circulation operation in the air conditioner of the present embodiment. In ST1, the forced circulation operation is performed, the on-off valve 13 is opened, the on-off valve 18 is closed, and the opening degree of the electronic expansion valve 4 is determined by depressurizing the refrigerant liquid that has exited the condenser 2 and changing the two-phase wet steam. , For example, about 15% of full opening. ST2
Receives the operation switching command in ST3, opens the on-off valve 18 in ST3, and opens the opening of the electronic expansion valve 4 in ST4 such that the outlet of the evaporator 7 becomes overheated, for example, about 10% of the full opening. Then, the refrigerant recovery operation is performed for a certain period of time (ST5). In the refrigerant recovery operation (ST5), the refrigerant liquid in the accumulator 14 evaporates due to the superheated gas from the evaporator 7 and the superheated gas discharged from the compressor 1 flowing through the bypass pipe 17 via the on-off valve 18. Then, it is recovered to the condenser 2 side via the compressor 1 and the check valve 16.

Next, the compressor 1 is stopped in ST6, and in ST7.
To close the on-off valve 13 to prevent the refrigerant from flowing into the accumulator 14. Then, in ST8, the on-off valve 18 is closed, the opening of the electronic expansion valve 4 is fully opened in order to reduce the pressure loss in the refrigerant circuit (ST9), and the operation shifts to natural circulation operation (ST10).

In the refrigerant recovery operation (ST5), a part of the high-temperature and high-pressure superheated gas discharged from the compressor 1 is bypassed to the suction side via the on-off valve 18 of the bypass pipe 17.
The refrigerant accumulated in the accumulator 14 can be collected in the natural circulation circuit without lowering the suction pressure of the compressor 1. In ST5, an example in which the refrigerant recovery operation is performed for a certain period of time is shown.
The discharge heating degree is detected, and the detected suction / discharge temperature and suction /
The refrigerant recovery operation may be performed until the discharge heating degree reaches the set value.

A bypass pipe 17 for connecting the high-pressure pipe and the low-pressure pipe via an on-off valve 18 is provided, and the operation is switched according to the procedure shown in FIG. There is an effect that the refrigerant accumulated in the compressor can be recovered in the cycle of the natural circulation operation, and the reliability of the compressor 1 can be improved.

The connection position of the bypass pipe 17 is not limited to the above-described position. As long as the low-pressure pipe is connected to the first inlet, the same effect as above can be obtained.

Embodiment 5 Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 5 of the present invention. FIG. 7 is a configuration diagram showing an air conditioner according to the present embodiment. In the figure, reference numeral 21 denotes a liquid receiver, which is provided in a pipe between the outlet of the condenser 2 and the inlet of the electronic expansion valve 4 and stores the refrigerant liquid flowing out of the condenser 2. The same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the arrows in the figure indicate the flow direction of the refrigerant. As in the first embodiment, the air conditioner according to the present embodiment includes an outdoor unit 5 and an indoor unit 9, and a liquid pipe 6 and a gas pipe 10 for connecting them. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. An electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid that has exited 2 and turns it into wet vapor in a two-phase state, in order to prevent the liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling. Accumulator 14, compressor 1 and on-off valve 13 for bypassing accumulator 14, compressor bypass pipe 12 via check valve 11, check valve for preventing refrigerant from flowing into compressor 1 during natural circulation operation 16,
Liquid receiver 2 for storing the refrigerant liquid flowing out of the outlet of condenser 2
1. The indoor unit 9 includes an evaporator 7 for evaporating wet steam flowing from the liquid pipe 6 by an air conditioning load, and an indoor fan 8.

The liquid receiver 21 is arranged below the condenser 2,
The pipe through which the refrigerant flows in from the condenser 2 and the pipe outflow to the electronic expansion valve 4 are connected to the lower part of the liquid receiver 21. The internal volume of the liquid receiver 21 is set to a volume capable of storing a refrigerant liquid corresponding to an appropriate refrigerant amount difference between the forced circulation operation and the natural circulation operation.

In this air conditioner, when the forced circulation operation is performed, the opening degree of the electronic expansion valve 4 is adjusted to an appropriate opening degree at which the refrigerant liquid flowing out of the condenser 2 is decompressed to two-phase wet steam. For example, by setting the opening degree to about 15% of the full opening, the compressor 1
To drive. Then, the check valve 11 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and a cycle of the forced circulation operation is formed. At this time, a liquid refrigerant corresponding to an appropriate refrigerant amount difference between the forced circulation operation and the natural circulation operation is stored in the liquid receiver 21. When the natural circulation operation is performed, the on-off valve 13
Is closed and the opening of the electronic expansion valve 4 is fully opened, the check valve 11 is opened by the flow of the refrigerant, and a natural circulation operation cycle is formed.

As shown in the fourth embodiment, when the refrigerant amount near the maximum cooling capacity of the natural circulation operation is filled, the surplus refrigerant is accumulated in the accumulator 14 during the forced circulation operation, and this is accumulated when the operation is switched. A refrigerant recovery operation for returning the surplus refrigerant to the refrigerant circuit during the natural circulation operation is required. In the air conditioner according to the present embodiment, since the liquid receiver 21 is provided near the outlet of the condenser 2, the condenser 2 is operated during the forced circulation operation.
It is possible to prevent a surplus refrigerant from being stored in the inside and to reduce a heat transfer area effective for condensation. In addition, since the excess refrigerant stays in the liquid receiver 21, the excess refrigerant can be prevented from staying in the accumulator 14, and the accumulator 14 can be reduced in size or omitted. In addition, since the surplus refrigerant does not stay in the accumulator 14, the refrigerant recovery operation becomes unnecessary, and the bypass pipe 17 via the electromagnetic valve 18 shown in the fourth embodiment can be omitted.

Embodiment 6 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 6 of the present invention. FIG. 8 is a configuration diagram showing an air conditioner according to the present embodiment. In the figure, reference numeral 19 denotes an oil separator for separating the refrigerating machine oil discharged together with the refrigerant gas from the compressor 1 and returning the oil to the compressor 1. The oil separator 19 is provided in a pipe between the outlet of the compressor 1 and the inlet of the condenser 2. Provided. Reference numeral 20 denotes a capillary for returning the refrigerating machine oil separated by the oil separator 19 to the compressor 1.
1 denote the same or corresponding parts, and
Arrows indicate the flow direction of the refrigerant. As in the first embodiment, an outdoor unit 5 and an indoor unit 9, and a liquid pipe 6 and a gas pipe 10 for connecting them are configured. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. An electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid that has exited 2 and turns it into wet vapor in a two-phase state, in order to prevent liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling. Accumulator 1
4. On-off valve 13 for bypassing compressor 1 and accumulator 14, compressor bypass pipe 12 via check valve 11, check valve 16 for preventing refrigerant from flowing into compressor 1 during natural circulation operation, Oil separator 1 that separates refrigerating machine oil discharged together with refrigerant gas from compressor 1 and returns it to compressor 1
9. It comprises a capillary tube 20 for returning the refrigerating machine oil separated by the oil separator 19 to the compressor 1. The indoor unit 9 includes an evaporator 7 for evaporating wet steam flowing from the liquid pipe 6 by an air conditioning load, and an indoor fan 8.

In this air conditioner, when the forced circulation operation is performed, the opening degree of the electronic expansion valve 4 is adjusted to an appropriate opening degree at which the refrigerant liquid flowing out of the condenser 2 is decompressed to two-phase wet steam. For example, by setting the opening degree to about 15% of the full opening, the compressor 1
To drive. Then, the check valve 11 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and a cycle of the forced circulation operation is formed. At this time, the refrigerant gas discharged from the compressor 1 flows into the condenser 2 after the refrigerating machine oil in the refrigerant gas is separated through the oil separator 19. The refrigerating machine oil separated by the oil separator 19 is decompressed by the capillary tube 20 and is compressed by the compressor 1.
Is returned to. When the natural circulation operation is performed, the on-off valve 1
When the electronic valve 3 is closed and the opening of the electronic expansion valve 4 is fully opened, the check valve 11 is opened by the flow of the refrigerant, and a natural circulation operation cycle is formed.

Generally, the refrigerating machine oil which flows out together with the discharge gas from the compressor 1 during the forced circulation operation returns to the compressor 1 during the natural circulation operation because the compressor 1 is bypassed by the on-off valve 13 and the check valve 16. No, it will circulate in the refrigerant circuit. Refrigeration oil circulating together with the refrigerant in the refrigerant circuit has an adverse effect such as a decrease in heat transfer coefficient and an increase in pressure loss. In particular, in the case of natural circulation operation, the thickness of the oil film attached to the wall surface in the gas pipe 10 serving as a riser becomes thicker because the refrigerant flow rate is smaller than that in the forced circulation operation,
This increases the pressure loss of the refrigerant circuit and causes a decrease in cooling capacity.

In the air conditioner according to the present embodiment, an oil separator 19 is provided at the outlet of the compressor 1 so that the refrigerating machine oil discharged together with the refrigerant gas can be separated and returned to the compressor 1. As a result, it is possible to suppress a decrease in cooling capacity caused by refrigerating machine oil circulating in the refrigerant circuit during natural circulation operation. In addition, since the refrigerating machine oil of the compressor 1 flows out to the refrigerant circuit, the amount of the refrigerating machine oil inside the compressor 1 decreases, and a phenomenon such as burning due to poor lubrication can be suppressed. There is an effect of improving.
In particular, incompatible oils such as alkylbenzene having low solubility in the refrigerant may be separated from the refrigerant even in the condenser 2, the evaporator 7, and the liquid pipe 6, resulting in an adverse effect such as a decrease in heat transfer coefficient and an increase in pressure loss. . In such a case, the effect of the air conditioner according to the present embodiment is further enhanced as compared with the case of using a refrigerating machine oil such as a mineral oil compatible with the refrigerant.

Embodiment 7 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 7 of the present invention. FIG. 9 is a configuration diagram showing an air conditioner according to the present embodiment. In the figure, reference numeral 23 denotes an expansion valve bypass pipe via an on-off valve (fifth on-off valve) 22 that bypasses the electronic expansion valve 4, and connects an outlet of the condenser 2 and an inlet of the evaporator 7. I have. The same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the arrows in the figure indicate the flow direction of the refrigerant. As in the first embodiment, the air conditioner according to the present embodiment includes an outdoor unit 5 and an indoor unit 9, and a liquid pipe 6 and a gas pipe 10 for connecting them. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas, a condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a condenser. An electronic expansion valve 4 which decompresses the high-temperature and high-pressure refrigerant liquid that has exited 2 and turns it into wet vapor in a two-phase state, in order to prevent the liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling. Accumulator 14, compressor 1 and on-off valve 13 for bypassing accumulator 14, compressor bypass pipe 12 via check valve 11, check valve for preventing refrigerant from flowing into compressor 1 during natural circulation operation 16, an expansion valve bypass pipe 23 via an on-off valve 22 for bypassing the electronic expansion valve 4. The indoor unit 9 includes an evaporator 7 for evaporating wet steam flowing from the liquid pipe 6 by an air conditioning load, and an indoor fan 8.

In the air conditioner according to the present embodiment, when the forced circulation operation is performed, the on-off valve 22 is closed, the on-off valve 13 is opened, and the opening degree of the electronic expansion valve 4 is determined by the refrigerant liquid flowing out of the condenser 2. Is set to an appropriate opening that reduces the pressure to a two-phase wet steam, for example, about 15% of the full opening, and the compressor 1
To drive. Then, the check valve 11 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and a cycle of the forced circulation operation is formed. When the natural circulation operation is performed, when the on-off valve 13 is closed, the on-off valve 22 is opened, and the opening of the electronic expansion valve 4 is fully opened, the check valve 11 is opened by the flow of the refrigerant, and the natural circulation operation is performed. Is formed. During the natural circulation operation, the refrigerant flowing out of the condenser 2 is branched and flows toward the electronic expansion valve 4 and the expansion valve bypass pipe 23. Normally, when the pressure loss of the refrigerant flowing through the electronic expansion valve 4 with the opening fully opened and the pressure loss of the refrigerant flowing through the expansion valve bypass pipe 23 that bypasses the electronic expansion valve 4 via the on-off valve 22 are compared, In many cases, the pressure loss of the valve bypass pipe 23 is smaller. Therefore, most of the refrigerant in the natural circulation operation actually flows through the expansion valve bypass pipe 23.

In the air conditioner according to the present embodiment, the pressure loss of the refrigerant in the liquid pipe can be greatly reduced by flowing the refrigerant through the expansion valve bypass pipe 23 during the natural circulation operation. For example, when the gas pipe 10 is long, it is possible to prevent a decrease in the cooling capacity of the natural circulation operation caused by an increase in the pressure loss in the refrigerant circuit. In addition, on-off valve 2
The electronic expansion valve 4 can be bypassed by the bypass circuit 23 via the valve 2. Therefore, even when the electronic expansion valve 4 is fixed at a certain opening during the forced circulation operation and fails, the on-off valve 22 is opened. Natural circulation operation can be performed, and the reliability of the system can be improved.

As described above, even if the electronic expansion valve 4 is fully opened in the natural circulation operation, most of the refrigerant flows through the expansion valve bypass pipe 23. The operation may be switched to the natural circulation operation in a state where the degree is set to the opening during the forced circulation operation. Even in this case, the cooling capacity hardly changes.

Embodiment 8 FIG. Hereinafter, a condenser used in, for example, a cooling device as an air conditioner according to Embodiment 8 of the present invention will be described. FIG. 10 is a configuration diagram showing a condenser relating to the air conditioner according to the present embodiment. In the figure, 24 is an inlet pipe, 25 is a heat transfer tube, 26 is a heat transfer tube 2
Fins orthogonal to 5; a supercooling section 27 provided at a lower portion in the condenser; and 28 an outlet pipe. A plurality of fins 26 are provided substantially parallel to each other, and a heat transfer tube 25 penetrates each of the fins 26 and is connected to a heat transfer tube 25 penetrated immediately below by an end fin 26 to form a refrigerant flow path. ing. Further, the heat transfer tube in the condenser is divided in the vertical direction to form a plurality of, for example, two refrigerant channels. The refrigerant gas that has flowed into the condenser is branched into two upper and lower flow paths by an inlet pipe 24, and releases heat to the outside air and condenses while flowing to the lower heat transfer tubes 25, respectively. Then, they merge at a portion A (portion indicated by a dotted circle) of the outlet pipe 28 to form one flow path, and flow into the supercooling section 27. The refrigerant having joined at the point A has a high flow velocity, is supercooled to some extent in the supercooling section 27, and flows into the liquid pipe from the refrigerant outlet (D1) of the condenser.

In this embodiment, the heat transfer tube 25 in the condenser
In the above configuration, the refrigerant is configured to flow downward from above. For example, when the refrigerant is configured to flow upward from below in the condenser, the condensed refrigerant stays in the heat transfer tube 25 due to gravity or flows backward in the heat transfer tube 25, and the refrigerant exits in the condenser. A phenomenon may occur in which the refrigerant liquid is not reliably supplied and the natural circulation operation is not established. In the condenser according to the present embodiment, since the flow direction of each refrigerant in the refrigerant flow path is configured to be downward from above, the condensed refrigerant liquid stays or flows backward in the heat transfer tube 25 particularly in natural circulation operation. Such a phenomenon can be prevented, and stable and appropriate cooling capacity can be obtained. In addition,
The refrigerant flow path is not limited to a configuration in which the refrigerant flow path is branched into two in the condenser. This can prevent a phenomenon in which the condensed refrigerant liquid stays or flows backward in the middle of the heat transfer tube 25, and a stable cooling capacity can be obtained particularly in natural circulation operation.

Further, in the present embodiment, the number of heat transfer tubes 25 constituting the two divided coolant flow paths is increased in the upper coolant flow path from the lower flow path, and the branched upper coolant flow path is lowered in the lower flow path. It is configured to be longer than the refrigerant passage on the side. Since the flow rate of the refrigerant flowing from the inlet pipe 24 is distributed so that the upper and lower pressure losses are equal, the upper refrigerant flow rate is smaller than the lower refrigerant flow rate. In general, in a condenser which is installed in the vertical direction as shown in FIG. 10 and is branched into two flow paths, when the upper and lower flow paths have the same length, a liquid column is formed in the outlet pipe 28 and the height difference is formed. , And the lower outlet pressure indicated by the point C becomes higher than the upper outlet pressure indicated by the point B. Therefore, the refrigerant is less likely to flow in the lower flow path,
The distribution of the flow rate of the refrigerant flowing from the inlet pipe 24 is uneven in the upper and lower directions. On the other hand, in the condenser according to the present embodiment, the number of heat transfer tubes 25 through which the refrigerant passes is increased on the upper side, so that the pressure loss of the refrigerant becomes larger in the upper refrigerant flow path, and the lower refrigerant The flow rate of the refrigerant is lower than that of the flow path. Therefore, the pressure difference caused by the height difference when the condenser is installed vertically can be absorbed by adjusting the number of the heat transfer tubes 25, and the flow rate distribution of the refrigerant can be made uniform. .

Further, if a rising pipe is provided from the bottom to the top in a connecting pipe between the outlet of the refrigerant of the condenser and the liquid pipe constituting the refrigeration cycle, the condensed refrigerant liquid rises in the rising pipe. And natural circulation operation may not be established. Such a phenomenon,
This is often seen when a sufficient degree of supercooling is not obtained in the condenser and bubbles are contained in the condensed refrigerant liquid. However, because of the piping, there is a case where a rising pipe is absolutely necessary, which has been a problem in natural circulation operation. In the condenser according to the present embodiment, the supercooling section 27 is provided at the lower portion, so that the degree of supercooling can be reliably obtained, and there is a certain rise pipe in the connection pipe between the outlet of the refrigerant of the condenser and the liquid pipe. Even in such a case, an air conditioner that can prevent the refrigerant from staying and can stably obtain appropriate cooling capacity can be obtained.

Although the above embodiment has been described with respect to an example in which the refrigerant flow path is branched into two, the same applies to a case in which the refrigerant flow path is branched into three or more in the vertical direction. Is configured to be larger than the pressure loss of the lower refrigerant flow path, a natural circulation operation in which an appropriate cooling capacity can be stably obtained can be performed. In order to configure the pressure loss of the upper refrigerant flow path to be larger than the pressure loss of the lower refrigerant flow path, as described above, in addition to increasing the number of the upper heat transfer tubes 25, The same effect can be obtained even if the inner diameter of the heat transfer tube 25 is reduced so that the refrigerant easily flows through the lower refrigerant passage.

Embodiment 9 Hereinafter, an evaporator used in, for example, a cooling device as an air conditioner according to Embodiment 9 of the present invention will be described. FIG. 11 is a configuration diagram showing an evaporator related to the air conditioner according to the present embodiment. In the figure, 24 is an inlet pipe, 25 is a heat transfer tube, 26 is a heat transfer tube 2
Fins orthogonal to 5 and 28 are outlet pipes. Similar to the configuration of the condenser, a plurality of fins 26 are provided substantially parallel to each other, and the heat transfer tubes 25 pass through each of the fins 26 and are connected to the heat transfer tubes 25 penetrated immediately above by the end fins 26. To form a refrigerant passage. The refrigerant that has flowed into the evaporator is branched into four upper and lower flow paths at the inlet pipe 24, and evaporates under the indoor air conditioning load while flowing from the lower part to the upper heat transfer pipe 25, respectively. Then, they merge at the outlet pipe 28,
The refrigerant flows into the gas pipe from the outlet (D2). In the present embodiment, the heat transfer tubes 25 through which the refrigerant passes in each branch flow path
And the lengths of the branched refrigerant channels are substantially equal to each other.

In general, when the heat transfer tube 25 in the evaporator 7 is configured from the upper side to the lower side, the evaporated refrigerant gas stays or rises in the heat transfer tube 25, and a reverse flow is generated in the heat transfer tube 25 to cause natural circulation. Operation may not be established. In the evaporator according to the present embodiment, since the flow direction of the refrigerant is from the lower side to the upper side, the evaporated refrigerant gas is supplied to the heat transfer tube 2.
The phenomenon of stagnation or backflow in the inside 5 can be prevented, and a natural circulation operation that can stably obtain an appropriate cooling capacity can be performed.

In the above embodiment, the refrigerant flow path is branched into four in the evaporator. However, the present invention is not limited to three flow paths, but two or less flow paths or four or more flow paths. It may be configured to branch to. If these refrigerant flow paths are configured to flow upward from below, the same effects as described above can be obtained.

Embodiment 10 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 10 of the present invention. FIG. 12 is a configuration diagram showing an air conditioner according to the present embodiment installed in a computer room or a base station (shelter) containing a relay electronic device for mobile communication. The outdoor unit 5 of the air conditioner is installed on a gantry fixed to the outer wall surface of the base station, and the indoor unit 9 is fixed to the wall surface inside the base station. Outdoor unit 5
And the indoor unit 9 are connected by a liquid pipe 6 and a gas pipe 10. The indoor unit 9 is installed at a minimum height leaving a working space from the floor such as a filter replacement. In addition, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

In the present embodiment, the heat transfer area of the evaporator in the indoor unit 9 is larger than the heat transfer area of the condenser in the outdoor unit 5. Here, the heat transfer area is the sum of the surface area of the fins forming the condenser and the evaporator and the surface area of the outside of all the heat transfer tubes forming the refrigerant flow path. Specifically, the heat transfer area can be reduced by changing the distance between the fins of the evaporator and the condenser, changing the number of stages and rows of the heat exchanger having the fins, and changing the outer diameter of the heat transfer tube. Can be changed.

The connection between the outdoor unit 5 and the liquid pipe 6 is provided at the lower part of the outdoor unit 5, and the height difference 29 between the outdoor unit 5 and the indoor unit 9 is set.
Was set within a range of 0.5 m or more and 2.0 m or less. Here, the height difference 29 is a difference between the height of the outlet of the refrigerant in the condenser and the height of the outlet of the refrigerant in the evaporator. Specifically, the height of the outlet portion D1 of the refrigerant after the branched refrigerant in the condenser shown in FIG.
It is the distance between the height of the outlet part D2 of the refrigerant | coolant after the branched refrigerant | coolant joined in the evaporator shown in FIG.

By the way, normally, in the forced circulation operation, as shown in FIG. 20, the enthalpy difference of the condenser is larger than the enthalpy difference of the evaporator by the input of the compressor.
Therefore, in general, the heat transfer area of the condenser is set to be larger than that of the evaporator in order to suppress an increase in the condensation pressure.
In general, as the heat transfer area increases, the air volume to the condenser is set to be larger than the air volume to the evaporator. On the other hand, in the case of the natural circulation operation, since the enthalpy difference and the pressure between the condenser and the evaporator are almost equal as shown in FIG. 21, the heat transfer area of the condenser is different from the case of the forced circulation operation. Need not be set larger than the evaporator.
That is, in the natural circulation operation as compared to the forced circulation operation, the enthalpy difference in the condenser is reduced, so that the heat transfer area of the condenser is reduced. By increasing the size, a refrigerant circuit suitable for natural circulation operation can be configured. In the air conditioner according to the present embodiment, since the heat transfer area of the evaporator is configured to be larger than the heat transfer area of the condenser,
A refrigerant circuit suitable for natural circulation operation can be provided.

FIG. 13 is a characteristic diagram showing the cooling capacity of the natural circulation operation with respect to the outside air temperature when the room temperature is B. The solid line 30 indicates the characteristic when the height difference between the outdoor unit 5 and the indoor unit 9 is large, for example, about 2 m, and the broken line 31 indicates the characteristic when the height difference is small, for example, about 0.5 m.
When the difference in height is large (solid line 30), the cooling capacity increases because the flow rate of the refrigerant increases as the outside air temperature decreases until the outside air temperature reaches point A. However, when the outside air temperature becomes equal to or lower than the point A, the rate of increase in the cooling capacity sharply decreases due to the restriction of the height difference, which is the driving force for flowing the refrigerant. On the other hand, when the height difference is small (broken line 31), the point at which the rate of increase in the cooling capacity sharply decreases rises to the point C, so that the range where the effective cooling capacity for the load is obtained becomes small.

FIG. 14 is a characteristic diagram showing the relationship between the height difference between the outdoor unit 5 and the indoor unit 9 and the cooling capacity. The solid line 32 indicates that the temperature difference between the outside air temperature and the room temperature is large, for example, ΔT = 2
The performance diagram when the temperature difference is about 0 ° C., and the solid line 33 shows the performance diagram when the temperature difference is small, for example, ΔT = about 10 ° C. In addition, this performance diagram shows that R
22 is used. When the temperature difference between the outside air temperature and the indoor temperature is large, the flow rate flowing in the refrigerant circuit increases with the height difference, so that the cooling capacity also increases with the height difference. Here, when the height difference is smaller than 0.5 m, the range where the effective cooling capacity for the load is obtained as indicated by the solid line 32 is small. Therefore, it is desirable that the height difference 29 between the condenser and the evaporator is 0.5 m or more.

On the other hand, if the height difference is too large, when the temperature difference between the outside air temperature and the room temperature is small, the length of the liquid pipe 6 or the gas pipe 10 increases with the increase in the height difference,
The pressure loss in the refrigerant circuit increases, and a phenomenon occurs in which the cooling capacity decreases or the natural circulation operation is not established, as shown by the solid line 33 in FIG. If the height difference is larger than 2 m, the refrigerating machine oil discharged together with the refrigerant gas from the compressor 1 during the forced circulation operation cannot rise in the gas pipe 6 serving as a rising pipe, and burnout due to poor lubrication of the compressor 1 will occur. Phenomena such as reduced capacity of natural circulation operation. In particular, when the height difference is larger than 2 m, the height of the entire base station (shelter) becomes high. Usually, trucks are used to transport products assembled at the factory so that adjustments are not troublesome.
If it is larger than m, problems arise such that transport becomes difficult, installation workability is reduced, and installation locations are limited. For these reasons, it is desirable that the height difference 29 between the condenser and the evaporator be 2 m or less.

In the air conditioner according to the present embodiment, the height difference 29 between the outdoor unit 5 and the indoor unit 9 is set within the range of 0.5 to 2 m, so that the above-described problem does not occur, and It is possible to obtain an air conditioner capable of stably obtaining an appropriate cooling capacity regardless of a temperature difference between the air conditioner and the room temperature. However, the cooling capacity obtained in the range of the height difference 29 set here slightly changes depending on the type of the refrigerant, the pressure loss of the refrigerant pipe, and the like. That is, a refrigerant having a small pressure loss, for example, R4
When 10A is used, the capacity diagram shown in FIG. 14 changes in the direction in which the cooling capacity increases, so that if the height difference is set within the above range, sufficient cooling capacity can be obtained.

Further, in the air conditioner according to the present embodiment, the refrigerant pipe extends further downward from the refrigerant outlet (D1) of the condenser 2 so that the liquid pipe 6 forming the refrigeration cycle is formed.
Is disposed below the bottom of the outdoor unit 5 which is a storage container of the condenser 2. Therefore, there is an effect that the work of connecting the liquid pipe 6 to the outdoor unit 5 installed at a high place becomes easy. Further, the same applies to the gas pipe 10, and the connection between the refrigerant inlet of the condenser 2 and the gas pipe 10 constituting the refrigeration cycle is set at a lower position than the bottom of the outdoor unit 5 which is a storage container of the condenser 2. If it is disposed below, the work of connecting the gas pipe 10 to the outdoor unit 5 installed at a high place can be facilitated.

Embodiment 11 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 11 of the present invention. FIG. 15 is a configuration diagram showing an air conditioner according to the present embodiment. In the figure, reference numeral 17 denotes a bypass pipe via a fourth on-off valve 18 connecting the high pressure pipe at the outlet of the compressor 1 and the accumulator 14, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In the figure, arrows indicate the flow of the refrigerant. As in the first embodiment, the air conditioner according to the present embodiment includes an outdoor unit 5, an indoor unit 9, a liquid pipe 6 for connecting them, and a gas pipe 10. The outdoor unit 5 includes a compressor 1 for compressing the refrigerant gas,
A condenser 2 for cooling and liquefying the refrigerant gas, an outdoor fan 3 for forcibly blowing outside air to the outer surface of the condenser 2, and a high-pressure and high-pressure refrigerant liquid exiting the condenser 2 are decompressed into two phases. An electronic expansion valve 4 that converts the wet steam into a state, an accumulator 14 for preventing liquid from returning to the compressor 1 in the event of a transient phenomenon or refrigerant overfilling, and the compressor 1 and the accumulator 14 during natural circulation operation. A first on-off valve 11 for bypassing, for example, a bypass pipe 12 via a check valve, a second on-off valve 13 for preventing refrigerant from flowing into the accumulator 14 during natural circulation operation, and a refrigerant to the compressor 1 during natural circulation operation Opening / closing valve 16 for preventing inflow of air, such as a check valve, a bypass piping 1 via a fourth opening / closing valve 18 connecting a high-pressure pipe at the outlet of the compressor 1 and the liquid refrigerant of the accumulator 14.
7. In addition, the indoor unit 9 evaporates the wet steam flowing from the liquid pipe 6 by the air conditioning load of the space to be air-conditioned and turns the evaporator 7 into a refrigerant gas, and forcibly blows indoor air to the outer surface of the evaporator 7. Of the indoor fan 8. The condenser 2 of the outdoor unit 5 is arranged at a position higher than the evaporator 7 of the indoor unit 9, and here, for example, is arranged with a height difference of about 1.4 m.

This air conditioner is used, for example, in places where cooling is required throughout the year. When the room temperature is lower than the outside air temperature, the room is cooled by the forced circulation operation. Indoor cooling is performed by natural circulation operation using cold heat. First, the forced circulation operation will be described. The opening of the electronic expansion valve 4 is set to an appropriate opening for reducing the pressure of the refrigerant liquid exiting the condenser 2 to two-phase wet steam.
When the compressor 1 is operated by opening the second opening / closing valve 13 four times before, the first opening / closing valve 11, for example, the check valve is closed due to the pressure difference between the discharge pressure and the suction pressure of the compressor 1, and the cycle of the forced circulation is performed. Is formed.

Next, the natural circulation operation when the outside air temperature is lower than the room temperature will be described. When the opening of the electronic expansion valve 4 is fully opened in order to reduce the pressure loss in the refrigerant circuit and the second on-off valve 13 in front of the accumulator 14 is closed, the first on-off valve 11, for example, the check valve flows through the refrigerant. And a cycle of natural circulation is formed. FIG.
5 is an experimental result showing changes in a cooling capacity, an evaporator outlet superheat degree, and a condenser outlet supercooling degree with respect to a refrigerant charging amount during a natural circulation operation in an experimental machine experimentally manufactured based on the configuration of FIG. FIG.
The upper diagram shows the measurement results of the cooling capacity, and the lower diagram shows the measurement results of the superheat degree (●) at the evaporator outlet and the supercooling degree (○) at the condenser outlet. The experimental condition is a temperature difference Δ between the room temperature and the outside air temperature.
In the case where T is constant at 33 ° C., the refrigerant filling amount on the horizontal axis indicates the refrigerant circuit filling amount in the natural circulation cycle. As can be seen from the upper diagram in FIG. 16, the cooling capacity shows a maximum value when the charged amount of the refrigerant is around 4 kg. The reason that the cooling capacity increases with an increase in the refrigerant charge is because the effective liquid column height increases with an increase in the refrigerant charge, and the refrigerant flow rate increases. In addition, the cooling capacity decreases with a further increase in the refrigerant charge, because the refrigerant at the evaporator outlet becomes a two-phase state, the enthalpy difference in the evaporator decreases, and the evaporator outlet to the condenser inlet This is because the pressure loss of the gas pipe increases and the refrigerant flow rate decreases. Further, as can be seen from the lower diagram of FIG. 16, when the cooling capacity is maximized (around 4 kg in the upper diagram of FIG. 16), the outlet of the evaporator is in a saturated gas state (superheat degree of the evaporator outlet is 0 ° C.). Therefore, in this case, the cooling capacity of the natural circulation operation can be maximized by setting the refrigerant charging amount to a value near 4 kg in the indoor / outdoor temperature difference,
The maximum power consumption reduction effect can be obtained. Also, 4k
Since the capacity reduction ratio with respect to the refrigerant amount is larger for 4 kg or more than for g or less, the amount of refrigerant to be charged should be set to be less than the filling amount when the cooling capacity is maximized (for example, 3.5 kg to 4.0 kg). If this is the case, the maximum cooling capacity can be obtained.

Further, since the appropriate amount of refrigerant in the forced circulation operation under the experimental conditions of FIG. 16 is about 2 kg, in order to maximize the cooling capacity of the natural circulation operation, it is twice (4 times) in the forced circulation operation.
It is understood that it is sufficient to charge the refrigerant amount of about / 2). In this case, the surplus refrigerant is accumulated in the accumulator 14 during the forced circulation operation, and it is necessary to perform a refrigerant recovery operation to return the surplus refrigerant to the refrigerant circuit of the natural circulation cycle when the operation is switched. As a method of the refrigerant recovery operation, the electronic expansion valve 4
The opening degree is made smaller (or fully closed) than in the normal forced circulation operation, and the forced circulation operation is performed for a certain time, and the liquid refrigerant in the accumulator 14 is evaporated by the superheated gas flowing from the evaporator outlet. At the same time, the on-off valve 18 is opened to allow the superheated gas discharged from the compressor 1 flowing through the bypass pipe 17 to flow into the liquid refrigerant in the accumulator 14, thereby foaming the liquid refrigerant and causing the refrigerant in the form of droplets to be dispersed in the gas. Is formed. In order to allow the refrigerant having a specific gravity larger than the gas to flow into the compressor 1 together with the gas, the excess refrigerant in the accumulator 14 is returned to the refrigerant circuit of the natural circulation cycle in a shorter time than the method of performing the refrigerant recovery operation using only the gas. It is possible.

Embodiment 12 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 12 of the present invention. FIG. 17 is a configuration diagram showing an accumulator of the air conditioner according to the present embodiment. In the figure, 30 is
An accumulator 1 penetrating through a suction pipe 31 connected to the compressor 1 in the accumulator 14 and a low-pressure pipe in the liquid refrigerant
Reference numeral 32 denotes a net attached to the opening 34 of the baffle plate 30. As in the eleventh embodiment, as a method of the refrigerant recovery operation, the opening degree of the electronic expansion valve 4 is made smaller (or fully closed) than in the normal forced circulation operation, and the forced circulation operation is performed for a certain time, The liquid refrigerant in the accumulator 14 is evaporated by the superheated gas flowing from the outlet. At the same time, the on-off valve 18 is opened to allow the superheated gas discharged from the compressor 1 flowing through the bypass pipe 17 to flow into the liquid refrigerant in the accumulator 14, thereby foaming the liquid refrigerant and causing the refrigerant in the form of droplets to be dispersed in the gas. Is formed. When a large amount of refrigerant in the form of droplets flows into the compressor 1, the refrigerating machine oil flows out into the refrigerant circuit together with the discharge gas,
There is a danger that the amount of refrigerating machine oil inside the compressor 1 decreases and burns due to poor lubrication. In particular, in the case of a scroll compressor, the amount of oil supplied to a sliding portion is reduced due to a decrease in suction pressure and a bubbling of a refrigerant liquid inside the compressor 1, and the sliding portion is thermally deformed due to a rise in temperature, leading to breakage. Problems arise. In this air conditioner, when a refrigerant recovery operation is performed, droplets of a certain size or more are attached to the net 32 by the net 32 attached to the baffle plate 30 or passed through the net 32,
By making the droplets fine and making the droplet-like refrigerant easier to vaporize, it is possible to suppress a large amount of the droplet-like refrigerant from flowing into the compressor 1. In addition, here, what provided the thing which adjusts the amount of splashes, such as the net | network 32 stuck on the baffle board 30, was provided.
The adjustment may be made by the opening 34 of the baffle plate 30. As described in the eleventh embodiment, since the refrigerant having the specific gravity larger than the gas flows into the compressor 1 together with the gas, the excess refrigerant in the accumulator 14 can be shortened in a shorter time than the method of performing the refrigerant recovery operation using only the gas. Can be returned to the refrigerant circuit of the natural circulation cycle, and since a large amount of splashed refrigerant flows into the compressor 1, it is possible to prevent the compressor 1 from being damaged.

Embodiment 13 FIG. Hereinafter, for example, a cooling device will be described as an air conditioner according to Embodiment 13 of the present invention. FIG. 18 shows a flowchart at the time of operation switching from forced circulation operation to natural circulation operation in the air conditioner of the present embodiment. In ST1 (step 1), the forced circulation operation is performed, the opening / closing valve 13 is opened, the opening / closing valve 18 is closed, and the opening degree of the electronic expansion valve 4 is set to two-phase by reducing the pressure of the refrigerant liquid that has exited the condenser 2. This is a state in which the opening is set to an appropriate degree to make the state wet steam. In ST2, the operation switching command is received, and in ST3, the opening of the electronic expansion valve 4 is changed to an opening or a fully closed state in which the evaporator outlet is in an overheated state.
At T4, the suction pressure allowable by the compressor 1 (for example, 1.5
kgf / cm2G) or more for a certain period of time. As a result, the liquid level of the liquid refrigerant 33 in the accumulator 14 decreases to some extent. Then, in ST5, the on-off valve 18 is opened,
In ST6, the superheated gas discharged from the compressor 1 flowing through the bypass pipe 17 via the on-off valve 18 is discharged to the accumulator 1
4 into the liquid refrigerant 33, the liquid refrigerant 3
The refrigerant is recovered for a certain period of time while foaming 3 to form a droplet-like refrigerant in the gas. Next, the compressor 1 is stopped in ST7, the on-off valve 13 is closed in ST8, and the accumulator 14 is closed.
To prevent refrigerant from flowing into Then, in ST9, the on-off valve 1
8 is closed, the opening of the electronic expansion valve 4 is fully opened to reduce the pressure loss in the refrigerant circuit (ST10), and the operation shifts to the natural circulation operation (ST11). By returning the liquid refrigerant 33 in the accumulator 14 to the refrigerant circuit of the natural circulation cycle in the refrigerant recovery for a certain time in ST4, the liquid refrigerant 33 decreases and the liquid level in the accumulator 14 decreases. Thereafter, in ST5, the on-off valve 18 is opened, and in the refrigerant recovery in ST6, the amount of the liquid refrigerant 33 is reduced by ST4, so that the amount of foaming is reduced, and the amount of splashed refrigerant is reduced. At the same time, when the liquid level decreases, the distance from the inlet of the suction pipe 31 connected to the compressor 1 in the accumulator 14 to the foamed refrigerant increases, so that the suction amount of the droplet-like refrigerant can be suppressed. Since it is possible to prevent a large amount of refrigerant in the form of droplets from flowing into the compressor 1, it is possible to prevent the compressor 1 from being damaged.

[0108]

According to the present invention, a refrigerating cycle in which a compressor, a condenser, an electronic expansion valve capable of controlling the opening of a valve, and an evaporator are sequentially connected by piping, and an outlet of the evaporator And a compressor bypass pipe connecting the inlet of the condenser with a first on-off valve via a first on-off valve, wherein the first on-off valve is closed and the compressor is in an operating state; By opening and closing the on-off valve and switching between natural circulation operation in which the compressor is stopped, and by controlling the opening of the electronic expansion valve in each of the forced circulation operation and the natural circulation operation, There is an effect that an air conditioner that can realize a simple configuration by realizing two functions of a pressure reducing function required for forced circulation operation and a bypass function of an expansion valve required for natural circulation operation with one electronic expansion valve is obtained. .

According to the present invention, the first on-off valve is a check valve that opens the flow of the refrigerant from the outlet of the evaporator to the inlet of the condenser and closes the flow in the opposite direction. There is no need to open and close according to forced circulation operation and natural circulation operation,
There is an effect that an air conditioner that can easily switch the refrigerant flow path can be obtained.

Further, according to the present invention, by providing an accumulator in the pipe between the inlet of the compressor bypass pipe and the inlet of the compressor, it is possible to absorb the excess refrigerant generated during the forced circulation operation. There is an effect that a machine can be obtained.

Further, according to the present invention, since the second on-off valve is provided in the pipe between the inlet of the compressor bypass pipe and the inlet of the accumulator, excess refrigerant generated during forced circulation operation can be absorbed. At the same time, it is possible to prevent the refrigerant from flowing after the operation is switched to the natural circulation operation, and to obtain an air conditioner that can always secure the amount of the refrigerant necessary for the natural circulation operation.

Further, according to the present invention, the provision of the heating means for heating the refrigerant in the accumulator eliminates the need for an on-off valve for preventing the refrigerant from flowing into the accumulator, thereby making it possible to form an inexpensive refrigerant circuit and to collect the refrigerant. There is an effect that an air conditioner that does not require operation and can reduce annual power consumption can be obtained.

The diameter of the gas pipe, which is the pipe from the outlet of the evaporator to the inlet of the condenser, is 1.5 times smaller than the diameter of the liquid pipe, which is the pipe from the outlet of the condenser to the inlet of the evaporator.
The pressure loss in the refrigerant circuit can be reduced because it is about twice as large.

Further, according to the present invention, since the compressor, the condenser and the electronic expansion valve are arranged in the outdoor unit and the evaporator is arranged in the indoor unit, the components of the refrigerant circuit can be easily stored in the outdoor unit. The effect that can be obtained is obtained.

According to the present invention, the high pressure pipe from the outlet of the compressor to the inlet of the condenser and the low pressure pipe from the outlet of the electronic expansion valve to the inlet of the compressor are opened and closed by the fourth opening and closing. By connecting with a bypass pipe via a valve, there is an effect that an air conditioner which can recover the refrigerant accumulated in the accumulator to the natural circulation circuit without lowering the suction pressure of the compressor is obtained.

As described above, according to the present invention, the high-pressure pipe from the outlet of the compressor to the inlet of the condenser and the accumulator are connected by the bypass pipe via the fourth opening / closing valve, so that the compressor is The refrigerant recovery operation can be performed in a shorter time without lowering the suction pressure of the air conditioner, and an air conditioner that can increase the power consumption reduction effect can be obtained.

Further, according to the present invention, by providing a mechanism for adjusting the amount of the refrigerant stored in the accumulator in the accumulator, the amount of the refrigerant liquid sucked from the suction pipe of the compressor can be suppressed. There is an effect that an air conditioner that can prevent breakage due to abnormally high pressure due to liquid compression inside the compressor can be obtained.

Further, according to the present invention, by providing the step of suppressing the amount of the refrigerant stored in the accumulator, the amount of the refrigerant liquid sucked from the suction pipe of the compressor is suppressed, and the inside of the compressor is reduced. There is an effect that a refrigerant control method capable of preventing breakage due to abnormal high pressure due to liquid compression can be obtained.

Also, according to the present invention, the provision of the receiver for storing the refrigerant liquid in the pipe between the outlet of the condenser and the inlet of the electronic expansion valve allows the condenser to be operated during the forced circulation operation. The effect of this is that an air conditioner can be obtained in which it is possible to prevent a surplus refrigerant from staying inside and reduce a heat transfer area effective for condensation, and to make the refrigerant recovery operation unnecessary because the surplus refrigerant stays in the receiver. There is.

Further, according to the present invention, the oil separator for separating the refrigerating machine oil is provided in the pipe between the outlet of the compressor and the inlet of the condenser. There is an effect that an air conditioner which can suppress a decrease in cooling capacity caused by refrigerating machine oil circulating in the air conditioner is obtained.

Further, according to the present invention, since the outlet of the condenser and the inlet of the evaporator are connected by the expansion valve bypass pipe via the fifth on-off valve, the liquid pipe and the gas pipe may be long. There is an effect that an air conditioner that can prevent a decrease in the cooling capacity of the natural circulation operation that occurs when the expansion valve fails and improves the reliability of the system can be obtained.

Further, according to the present invention, a compressor, a condenser,
A refrigeration cycle in which an expansion valve and an evaporator are sequentially connected by a pipe; a compressor bypass pipe connecting an outlet of the evaporator and an inlet of the condenser via a first on-off valve; A third on-off valve provided in a pipe between an outlet of the compressor and an outlet of the compressor bypass pipe, wherein the first on-off valve is closed, the third on-off valve is opened, and the compressor is operated. Forced circulation operation, the first on-off valve is opened, and the third
The on-off valve is closed and the compressor can be switched between the natural circulation operation and the stopped state, thereby preventing the refrigerant gas from flowing into the compressor and condensing during the natural circulation operation, which is necessary for the natural circulation operation. This has the effect of obtaining an air conditioner that can secure a large amount of refrigerant and improve the reliability of the compressor.

Further, according to the present invention, the third on-off valve is a check valve that opens the flow of the refrigerant from the outlet of the compressor to the outlet of the compressor bypass pipe and closes the flow in the opposite direction. By doing so, there is an effect that there is no need to open and close according to the forced circulation operation and the natural circulation operation, and an air conditioner that can easily shut off the flow of the refrigerant into the compressor is obtained.

Further, according to the present invention, since the refrigerant flowing into the condenser flows downward from above in the condenser, the condensed refrigerant liquid stays or flows backward in the heat transfer tube. There is an effect that an air conditioner that can prevent a phenomenon that the natural circulation operation is not established can be obtained.

Further, according to the present invention, the refrigerant pipe in the condenser is vertically divided into a plurality of refrigerant flow paths, and each of the branched refrigerant flows from the upper side to the lower side in the refrigerant flow path to form the condenser. A supercooling section is provided at the lower part in the condenser, and the degree of supercooling is reliably obtained, and a rising pipe is provided in a connecting pipe between the condenser outlet and the liquid pipe. Has the effect of obtaining an air conditioner that can prevent the stagnation of the refrigerant liquid even when the air conditioner exists.

Further, according to the present invention, the refrigerant pipe in the condenser is vertically divided into a plurality of refrigerant passages, and each of the branched refrigerants flows from the upper side to the lower side of the refrigerant passage to form the condenser pipe. The length of the upper refrigerant flow path is made longer than the length of the lower refrigerant flow path, and the flow rate distribution of the refrigerant to the plurality of refrigerant flow paths is configured by configuring so as to join at the outlet of the vessel. There is an effect that an air conditioner that can be made uniform can be obtained.

Further, according to the present invention, since the refrigerant flowing into the evaporator is configured to flow upward from below in the evaporator, a phenomenon in which the evaporated refrigerant gas stays or flows backward in the heat transfer tube. This has the effect of providing an air conditioner that can suppress air pollution.

Further, according to the present invention, the pipe diameter from the outlet of the evaporator to the inlet of the condenser is made larger than the pipe diameter from the outlet of the condenser to the inlet of the evaporator. In addition, there is an effect that an air conditioner that can reduce the pressure loss in the refrigerant circuit and suppress a decrease in the cooling capacity of the natural circulation operation can be obtained.

Further, according to the present invention, by making the heat transfer area of the evaporator larger than the heat transfer area of the condenser, it is possible to obtain an air conditioner capable of providing a refrigerant circuit suitable for natural circulation operation. This has the effect.

According to the present invention, the height of the outlet of the refrigerant pipe of the condenser is 0.5 m or more and 2 m or less higher than the height of the outlet of the refrigerant pipe of the evaporator. , Regardless of the temperature difference between the outside air temperature and the indoor temperature,
There is an effect that an air conditioner that can provide appropriate cooling capacity can be obtained.

According to the present invention, the connection between the outlet of the refrigerant pipe of the condenser and the liquid pipe constituting the refrigeration cycle is disposed below the bottom of the storage container of the condenser. This has the effect of providing an air conditioner that facilitates pipe connection work to an outdoor unit installed at a high place.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram showing an air conditioner according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram showing an air conditioner according to Embodiment 4 of the present invention.

FIG. 5 is a characteristic diagram illustrating a cooling capacity with respect to a ratio of a charged amount of refrigerant in an air conditioner according to Embodiment 4.

FIG. 6 is a flowchart showing an operation switching procedure of the air conditioner according to Embodiment 4 from forced circulation operation to natural circulation operation.

FIG. 7 is a configuration diagram illustrating an air conditioner according to Embodiment 5 of the present invention.

FIG. 8 is a configuration diagram showing an air conditioner according to Embodiment 6 of the present invention.

FIG. 9 is a configuration diagram illustrating an air conditioner according to a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram showing a condenser according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram showing an evaporator according to a ninth embodiment of the present invention.

FIG. 12 is a configuration diagram showing an arrangement of an air conditioner attached to a base station according to Embodiment 10 of the present invention.

FIG. 13 is a characteristic diagram showing a change in cooling capacity with respect to the outside air temperature of the air conditioner according to Embodiment 10.

FIG. 14 is a characteristic diagram showing a change in cooling capacity with respect to a height difference between an indoor unit and an outdoor unit of the air conditioner according to Embodiment 10.

FIG. 15 is a configuration diagram showing an air conditioner according to Embodiment 11 of the present invention.

FIG. 16 is a diagram showing experimental results of the air conditioner according to Embodiment 11 of the present invention.

FIG. 17 is a configuration diagram showing an accumulator according to a twelfth embodiment of the present invention.

FIG. 18 is a flowchart showing a procedure for switching operation from forced circulation operation to natural circulation operation according to Embodiment 13 of the present invention.

FIG. 19 is a configuration diagram showing an air conditioner for explaining an operation principle of a cooling operation by natural circulation.

FIG. 20 is a characteristic diagram showing a relationship between pressure and enthalpy during forced circulation operation.

FIG. 21 is a characteristic diagram showing a relationship between pressure and enthalpy during natural circulation operation.

FIG. 22 is a configuration diagram showing a conventional air conditioner provided with a natural circulation operation and a forced circulation operation.

[Description of Signs] 1 compressor, 2 condenser, 3 outdoor fan, 4 electronic expansion valve, 5 outdoor unit, 6 liquid piping, 7 evaporator, 8 indoor fan, 9 indoor unit, 10 gas piping, 11 first On-off valve, 12 Compressor bypass pipe, 13 Second on-off valve, 1
4 accumulator, 15 heating means, 16 third on-off valve, 17 bypass pipe, 18 fourth on-off valve, 19 oil separator, 20 capillary tube, 21 liquid receiver, 22 fifth on-off valve, 23 expansion valve bypass pipe, 24 inlet Plumbing, 25
Heat transfer tube, 26 fins, 27 supercooling section, 28 outlet pipe, 29 height difference, 30 baffle plate, 31 suction pipe, 32 mesh, 33 liquid refrigerant, 34 opening.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Yoshii 2-6-1 Otemachi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Engineering Co., Ltd. (72) Inventor Ittaro Akiyama 2-6-Otemachi, Chiyoda-ku, Tokyo No. 2 Inside Mitsubishi Electric Engineering Co., Ltd. (72) Inventor Yasunori Shida 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Akio Fukushima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi (56) References JP 55-10828 (JP, B2) JT 55-29394 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 1 / 00 F24F 11/02

Claims (24)

(57) [Claims] 1. A refrigeration cycle in which a compressor, a condenser, an electronic expansion valve capable of controlling the opening of a valve and an evaporator are sequentially connected by piping, an outlet of the evaporator and an inlet of the condenser. and a compressor bypass pipe for connecting the parts via a first on-off valve, the first on-off valve is closed, the compressor, condenser
A compressor , an electronic expansion valve, and an evaporator are sequentially connected , and a forced circulation operation in which the compressor is in an operating state, the first on-off valve is opened , the compressor is bypassed to bypass the compressor,
The secondary expansion valve and the evaporator are sequentially connected to enable switching between the natural circulation operation in which the compressor is stopped and control the pressure state of the refrigerant during the forced circulation operation.
In order to reduce the pressure loss during the natural circulation operation,
The degree of opening of the electronic expansion valve is larger than that during the forced circulation operation.
An air conditioner characterized by controlling the air conditioner. 2. The check valve according to claim 1, wherein the first on-off valve is a check valve that opens the flow of the refrigerant from the outlet of the evaporator to the inlet of the condenser and closes the flow in the opposite direction. 2. The air conditioner according to 1. 3. The air conditioner according to claim 1, wherein an accumulator is provided in a pipe between an inlet of the compressor bypass pipe and an inlet of the compressor. 4. The air conditioner according to claim 3, wherein a second on-off valve is provided in a pipe between an inlet of the compressor bypass pipe and an inlet of the accumulator. 5. The air conditioner according to claim 3, further comprising a heating means for heating the refrigerant in the accumulator. 6. The arrangement from the outlet of the evaporator to the inlet of the condenser.
From the outlet of the condenser, the diameter of the gas pipe
1.5 to 2 times smaller than the diameter of the liquid pipe that is the pipe to the inlet
2. The air according to claim 1, wherein the air is about twice as large.
Harmony machine. 7. A compressor, a condenser and an electronic expansion valve are housed in a chamber.
The evaporator is located in the indoor unit and the evaporator is located in the outdoor unit.
The air conditioner according to claim 1, wherein 8. A bypass pipe via a fourth on-off valve between a high pressure pipe from an outlet of a compressor to an inlet of a condenser and a low pressure pipe from an outlet of an electronic expansion valve to an inlet of the compressor. To switch from forced circulation operation to natural circulation operation.
The air conditioner according to any one of claims 3 to 6 , wherein the fourth on-off valve is opened at the time of replacement . 9. A high pressure pipe from an outlet of the compressor to an inlet of the condenser and an accumulator are connected by a bypass pipe via a fourth on-off valve, and a part of the heated gas discharged from the compressor is connected to the accumulator. The refrigerant stored in the accumulator by forced circulation operation is recovered by a refrigerant circuit of a natural circulation operation by flowing into a liquid refrigerant stored in the accumulator from a bypass pipe and spraying the refrigerant. The air conditioner according to any one of claims 3 to 6 . 10. The air conditioner according to claim 9, wherein a mechanism for adjusting the amount of the refrigerant stored in the accumulator is provided in the accumulator. 11. The air conditioner according to claim 9, further comprising a step of suppressing a splash amount of the refrigerant stored in the accumulator. 12. A liquid receiver for storing a refrigerant liquid is provided in a pipe between an outlet of a condenser and an inlet of an electronic expansion valve. Any one
An air conditioner according to the item. 13. An oil separator for separating refrigerating machine oil is provided in a pipe between an outlet of a compressor and an inlet of a condenser. Or 1
An air conditioner according to the item. 14. An apparatus according to claim 1, wherein the outlet of the condenser and the inlet of the evaporator are connected by an expansion valve bypass pipe via a fifth on-off valve.
An air conditioner according to the item. 15. A compressor outlet and a compressor bypass pipe.
A third on-off valve is provided in a pipe between the outlet and the first on- off valve , the first on- off valve is closed, the third on-off valve is opened, and the compressor is operated in a forced circulation operation; The air conditioner according to claim 1, wherein the air conditioner can be switched between a natural circulation operation in which the third open / close valve is closed and the compressor is stopped in an open state. 16. The check valve according to claim 16, wherein the third on-off valve is a check valve that opens the flow of the refrigerant from the outlet of the compressor to the outlet of the compressor bypass pipe and closes the flow in the opposite direction. The air conditioner according to claim 15. 17. The air conditioner according to claim 1, wherein the refrigerant flowing into the condenser is configured to flow downward from above in the condenser. Machine. 18. A refrigerant pipe in a condenser is divided in a vertical direction into a plurality of refrigerant passages, and each of the branched refrigerants flows through the refrigerant passages from above to below and joins at an outlet of the condenser. 18. The air conditioner according to claim 17, wherein a supercooling section is provided at a lower portion in the condenser. 19. A refrigerant pipe in a condenser is vertically divided into a plurality of refrigerant passages, and each of the branched refrigerants flows through the refrigerant passages from above to below and joins at an outlet of the condenser. 19. The air conditioner according to claim 17, wherein the air conditioner is configured so that the length of the upper refrigerant flow path is longer than the length of the lower refrigerant flow path. 20. The air conditioner according to claim 1, wherein the refrigerant flowing into the evaporator is configured to flow information from below in the evaporator. Machine. 21. The pipe diameter from the outlet of the evaporator to the inlet of the condenser is larger than the pipe diameter from the outlet of the condenser to the inlet of the evaporator. The air conditioner according to any one of claims 20 to 20. 22. The heat transfer area of the evaporator is larger than the heat transfer area of the condenser.
2. The air conditioner according to any one of 1. 23. The height of the outlet of the refrigerant pipe of the condenser,
The height is 0.5 m or more and 2 m or less higher than the height of the outlet part of the refrigerant pipe of the evaporator.
The air conditioner according to any one of claims 22. 24. A connection part between an outlet part of a refrigerant pipe of a condenser and a liquid pipe constituting a refrigeration cycle is disposed below a bottom part of a storage container of the condenser.
The air conditioner according to any one of claims 23 to 23.