JP2003240366A - Refrigerating air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that flow-in of oil into an evaporator is impossible to be restrained while securing oil supply to an expander when using the expander as a pressure reducing device, in a conventional refrigerating air-conditioner using carbon dioxide gas refrigerant. <P>SOLUTION: In a refrigerating cycle connected with a compressor, a heat radiator, the pressure reducing device and an evaporator in order, carbon dioxide gas is used as a refrigerant, the expander is used as the pressure reducing device, an oil separator is provided between the pressure reducing device and the evaporator, and heat-transfer performance is thereby prevented from being lowered in the evaporator to provide the refrigerating air-conditioner of high operation efficiency. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration air conditioning system, and more particularly to a refrigeration air conditioning system using carbon dioxide as a refrigerant.

[0002]

2. Description of the Related Art As a refrigerating and air-conditioning apparatus that uses carbon dioxide as a refrigerant, there is a refrigerating and air-conditioning apparatus described in JP-A-2000-55488. FIG. 9 shows a refrigeration cycle described in this patent, in which 1 is a compressor, 4 is an oil separator, and 2 is a compressor.
Is a radiator, 15 is an expansion valve, 5 is an evaporator, and carbon dioxide (CO ₂ ) is used as a refrigerant. The flow of the refrigerant in this refrigeration air conditioner is as follows. First, the refrigerant compressed in the high-temperature and high-pressure gas in the compressor 1 and discharged is cooled by the radiator 2 in the supercritical state, and the temperature thereof drops. The refrigerant is decompressed by the expansion valve 15, the refrigerant is in a low-pressure two-phase state, flows into the evaporator 5, is evaporated and gasified therein, and is sucked into the compressor 1. Refrigerating machine oil discharged from the compressor 1 together with the refrigerant is separated by the oil separator 4 and returned to the compressor 1. With such a structure, a gas density is high like a carbon dioxide refrigerant, and even if a refrigerant with a slow flow rate is used,
It was possible to prevent the refrigerating machine oil from accumulating in the heat exchanger and the piping, to suppress an increase in pressure loss due to the accumulating refrigerating machine oil, and to downsize the equipment.

[0003]

However, the conventional example has the following problems. In a refrigeration cycle using carbon dioxide, the power that can be recovered when expanding due to the characteristics of the refrigerant is large, so an expander that recovers that power is used instead of the expansion valve or in combination with the expansion valve. Since the expander has sliding parts, it is essential to supply refrigerating machine oil for lubrication. However, in the conventional example, since the oil separator 4 is provided at the outlet of the compressor 1, the compressor 1
Most of the refrigerating machine oil discharged from the compressor is returned to the compressor 1, and the refrigerating machine oil is no longer supplied to the expander,
There is a problem that the reliability of the expander operation is reduced.

Further, in order to supply refrigerating machine oil to the expander,
If the oil separator 4 is not provided at the outlet of the compressor 1, refrigerating machine oil is supplied to the expander, but since the refrigerating machine oil circulates throughout the refrigerant circuit, the refrigerating machine oil also flows into the evaporator 4. . When a refrigerant having a higher operating pressure than that of a conventional refrigerant such as carbon dioxide is used, the gas density becomes large and the refrigerant flow velocity in the evaporator 4 also decreases. Then, the form of heat transfer in the evaporator 4 is such that the boiling heat transfer that improves the heat transfer performance by boiling the refrigerant is more than the convective heat transfer that improves the heat transfer performance by the convection effect caused by the flow of the refrigerant. Becomes dominant. The boiling heat transfer is performed by the refrigerant boiling and the generation of bubbles in the fine cavities (holes) on the surface of the heat transfer tube. At this time, when the amount of oil in the refrigerator flowing into the evaporator 4 is large, when the refrigerant boils and bubbles tend to be generated, an oil film is formed on the surface of the heat transfer tube, which becomes a resistance and suppresses the generation of bubbles. Therefore, when the oil separator 4 is not provided and the amount of oil inflowing into the evaporator 4 increases, the heat transfer performance in the evaporator 4 deteriorates, which in turn lowers the operating efficiency of the refrigerating and air conditioning equipment. was there.

The present invention has been made in view of the above problems, and an object thereof is to obtain a refrigerating and air-conditioning apparatus having high operation efficiency. Another object of the present invention is to obtain a refrigerating and air-conditioning apparatus with high operating efficiency by suppressing a decrease in heat transfer performance due to refrigerating machine oil in the evaporator. Moreover, it aims at obtaining the refrigerating air-conditioning apparatus which uses carbon dioxide as a refrigerant | coolant and has high operation efficiency. Another object of the present invention is to obtain a refrigerating and air-conditioning apparatus that uses an expander as a decompression device and has high operating efficiency.

[0006]

A refrigerating and air-conditioning apparatus according to claim 1 of the present invention is a refrigerating and air-conditioning apparatus in which a compressor, a radiator, a decompression device, and an evaporator are sequentially connected, and between the decompression device and the evaporator. It has an oil separator.

A refrigerating air-conditioning apparatus according to a second aspect of the present invention is the refrigerating air-conditioning apparatus according to the first aspect, further comprising a heat exchanger for recovering the cold heat of the separated refrigerating machine oil.

According to a third aspect of the present invention, there is provided the refrigerating and air-conditioning apparatus according to the first aspect.
Alternatively, in the refrigerating and air-conditioning apparatus according to claim 2, the refrigerating machine gas is separated together with the refrigerating machine oil by the oil separator and returned to the compressor without passing through the evaporator.

A refrigeration / air-conditioning apparatus according to a fourth aspect is a refrigeration / air-conditioning apparatus in which a compressor, a radiator, a decompression device, and an evaporator are sequentially connected, and the flow path in the evaporator is branched into a plurality of flow paths. In addition to providing a distributor, among the channels distributed by the distributor, a large number of channels having a large amount of refrigerating machine oil are arranged in the heat exchanger where the heat flux is large.

The refrigerating air-conditioning apparatus according to a fifth aspect of the present invention is the refrigerating air-conditioning apparatus according to the fourth aspect, wherein the flow passage having a large amount of refrigerating machine oil is a flow passage into the lower portion of the evaporator.

The refrigerating air conditioner according to claim 6 is the refrigerating air conditioner according to claim 4 or 5, in which a large heat flux has a large temperature difference between the temperature of the refrigerant and the temperature of the heat exchange medium of the heat exchanger. It is a place that becomes.

A refrigerating air-conditioning apparatus according to claim 7 is the refrigerating air-conditioning apparatus according to any one of claims 1 to 6, wherein an expander is provided as a pressure reducing device.

A refrigerating air-conditioning apparatus according to claim 8 is the refrigerating air-conditioning apparatus according to any one of claims 1 to 7, wherein carbon dioxide is used as a refrigerant.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 shows the refrigerant circuit of the refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention. Figure 1
In the above, 1 is a compressor, 2 is a radiator, 3 is an expander used as a pressure reducing device, 4 is an oil separator, and 5 is an evaporator. The compressor 1 is a compressor driven by a motor, and the drive shaft 7 of the motor 6 is connected to the drive shaft 7 of the expander 3. The expander 3 recovers the power generated when the refrigerant expands and transmits the power to the drive shaft 7 connected to the compressor 1. In the compressor 1, since a part of the compression work in the compressor 1 is performed by the expansion power, the electric input required in the compressor 1 is reduced as compared with the case where the expansion power is not recovered, and the refrigeration air conditioner is operated. Is increasing the efficiency of. Again 8
Is a return oil pipe for returning the refrigerating machine oil separated by the oil separator 4 to the suction portion of the compressor 1. Further, in the refrigerating air-conditioning apparatus, carbon dioxide is used as the refrigerant, and PAG oil having low solubility and high density with respect to carbon dioxide is used as the refrigerating machine oil.

Next, the flow of the refrigerant in this refrigerating and air conditioning system will be described. Compressed by the compressor 1 and discharged at high temperature
The temperature of the high-pressure gas refrigerant drops while radiating heat in the radiator 2. At this time, if the high pressure is equal to or higher than the critical pressure, the temperature of the refrigerant drops in the supercritical state and heat is released. If the high pressure is below the critical pressure, the refrigerant radiates and radiates heat. The expansion power is applied to the drive shaft 7 while the refrigerant exiting the radiator 2 is expanded by the expander 3.
Communicate to. The expansion of the expander 3 causes the refrigerant to be in a low-pressure two-phase state and flow into the evaporator 5. The refrigerant is vaporized and gasified in the evaporator 5, and is sucked into the compressor 1.

Next, the flow of refrigerating machine oil in this refrigerating and air conditioning system will be described. Refrigerating machine oil discharged together with the refrigerant in the compressor 1 flows into the expander 3 via the radiator 2, lubricates sliding parts such as bearings in the expander 3, and then flows into the oil separator 4. Here, the refrigerating machine oil is separated from the refrigerant, and the separated refrigerating machine oil is returned to the suction portion of the compressor 1 through the oil return pipe 8.

The structure of the oil separator 4 is as shown in FIG. In the oil separator 4, the refrigerant is in a gas-liquid two-phase state, and refrigerating machine oil is added to this, so that saturated gas, saturated liquid, and refrigerating machine oil exist. In this refrigerating air conditioner, carbon dioxide is used as the refrigerant and PAG oil is used as the refrigerating machine oil as described above, and the refrigerant and the refrigerating machine oil have the above-mentioned characteristics,
In the oil separator 4, it is separated into three phases of gas refrigerant, liquid refrigerant, and refrigerating machine oil by gravity. The oil return pipe 8 is connected to the bottom of the oil separator 4, and the refrigerating machine oil accumulated at the bottom of the oil separator 4 flows into the oil return pipe 8 and passes through the oil return pipe 8 to the compressor 1 suction part. Inflow. Also, gas refrigerant and liquid refrigerant are used for the evaporator 5.
Gas return hole 9a and liquid return hole 9 provided in the pipe leading to
It flows into the evaporator 4 through b.

As described above, the oil separator 4 is provided between the expander 3 and the evaporator 5, the refrigerating machine oil is separated by the oil separator 4, and the oil is returned to the compressor 1, whereby the compressor 1 is separated from the compressor 1. By supplying the discharged refrigerating machine oil to the expander 3 and lubricating the sliding part of the expander 3, the reliability of the operation of the expander 3 is increased, and a highly reliable refrigerating air conditioner is obtained, and the evaporator is also provided. By suppressing the inflow of the refrigerating machine oil into the refrigerating machine 5, and suppressing the deterioration of the heat transfer performance in the evaporator 5, the operation efficiency of the refrigerating and air-conditioning apparatus can be improved.

The structure of the oil separator 4 may be the structure shown in FIG. In FIG. 3, among the refrigerant and the refrigerating machine oil separated into three phases in the oil separator 4, the gas refrigerant is sucked into the compressor 1 together with the refrigerating machine oil through the pipe 16 connected to the top of the oil separator 4. It is structured to flow into the oil return pipe 8 returning to the section. By doing so, it is possible to adopt a structure in which the gas refrigerant having no cooling capacity due to evaporation does not flow into the evaporator 4 but directly flows into the suction portion of the compressor 1. Therefore, the flow rate of the refrigerant flowing through the evaporator 4 can be reduced, and the pressure loss in the evaporator 4 can be reduced, so that a refrigerating air-conditioning apparatus with higher operating efficiency can be obtained.

The structure of the oil separator 4 may be that shown in FIG. The oil separator 4 shown in FIG. 4 is a cyclone type oil separator, and the refrigerant and the refrigerating machine oil are swirled in the circumferential direction of the oil separating machine 4, and the refrigerating machine oil having the highest density is separated by centrifugal separation. The refrigerant gas and the refrigerant liquid other than the above are introduced into the evaporator 5 through the pipe at the center of the oil separator 4. An oil return pipe 8 is connected to the bottom of the oil separator 4, and the separated refrigerating machine oil is returned to the compressor 1 suction section.

The structure of the oil separator 4 may be that shown in FIG. In the oil separator 4 shown in FIG. 5, a porous membrane 10 for separating an organic substance and an inorganic substance is provided inside, and the membrane 10 is an organic substance that does not permeate a carbon dioxide refrigerant which is an inorganic substance. PAG oil is permeable. Refrigerating machine oil that permeates the membrane 10 stays at the bottom of the oil separator 4 and is returned to the suction portion of the compressor 1 through the oil return pipe 8 at the bottom. The carbon dioxide refrigerant that does not pass through the membrane 10 stays in the upper part of the oil separator 4 and flows out from the oil separator 4 to the evaporator 5.

With any of the above-mentioned structures of the oil separator 4, it is possible to supply the refrigerating machine oil to the expander 3,
Since the inflow of refrigerating machine oil to the evaporator 5 can be suppressed, it is possible to obtain a refrigerating and air-conditioning apparatus with high reliability and high operating efficiency. In the radiator 2, the effect of refrigerating machine oil is smaller than that of the evaporator because the form of heat transfer is convective heat transfer control.

In this embodiment, if the evaporator 5 is connected downstream of the oil separator 4, even if a pressure reducing device such as another expansion valve is provided between the oil separator 4 and the evaporator 5. , A similar effect can be obtained. Further, even when the expander 3 is not used in the refrigeration air conditioner and a valve such as an expansion valve is used as the pressure reducing device, oil separation is performed between the expansion valve and the evaporator 5 as shown in the present embodiment. By providing the device 4, it is possible to suppress the inflow of refrigerating machine oil into the evaporator 5 and obtain a refrigerating air-conditioning system with high operating efficiency.

The refrigerant is not limited to carbon dioxide, and any refrigerant such as HFC type refrigerant, HC type refrigerant, water, air, or natural refrigerant such as ammonia (NH ₃ ) may be used. With the configuration, the same effect can be obtained. Also for refrigeration oil, PAG
The same effect can be obtained by using the same refrigerating and air-conditioning apparatus configuration when the refrigerating machine oil such as ester oil, ether oil, alkylbenzene oil, and mineral oil is not limited to oil.

Embodiment 2. Hereinafter, a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 2 of the present invention is shown in FIG. In FIG. 6, 11 is a high / low pressure heat exchanger provided in the middle of the oil return pipe 8. The other reference numerals in FIG. 6 are the same as those in FIG. The high / low pressure heat exchanger 11 has a structure for exchanging heat with the refrigerating machine oil separated by the oil separator 4 and the refrigerant at the outlet of the radiator 2, and is configured using, for example, a double pipe. Since the temperature of the refrigerant at the outlet of the radiator 2 becomes higher than the temperature of the refrigerating machine oil, the temperature of the refrigerant at the outlet of the radiator 3 lowers and the temperature of the refrigerating machine oil returned increases by performing heat exchange.

A small amount of liquid refrigerant is dissolved in the refrigerating machine oil separated by the oil separator 4, even though the refrigerant and refrigerating machine oil have low solubility. If the refrigerating machine oil separated by the oil separator 4 is returned to the compressor 1 as it is, the liquid refrigerant dissolved in the refrigerating machine oil is also sucked into the compressor 1 as it is, and the cooling capacity of the liquid refrigerant is the evaporator. Therefore, the operating efficiency of the refrigerating and air-conditioning system is reduced. Therefore, by exchanging heat between the refrigerating machine oil and the refrigerant at the outlet of the radiator 2, the cooling capacity of the liquid refrigerant dissolved in the refrigerating machine oil together with the refrigerating machine oil is recovered.
It is given to the refrigerant at the outlet of the radiator 2. By thus recovering the cooling capacity of the liquid refrigerant that is returned to the suction portion of the compressor 1 together with the refrigerating machine oil, it is possible to suppress a reduction in the efficiency of operation of the refrigerating and air conditioning apparatus due to oil separation and obtain a refrigerating and air conditioning apparatus with high operation efficiency. it can.

The structure of the high and low pressure heat exchanger 11 is not limited to the double pipe, and may have any structure such as a shell and tube type, a plate heat exchange, a structure in which pipes and pipes are brazed. , A similar effect can be obtained.

Embodiment 3. Hereinafter, the refrigerant circuit of the refrigerating and air-conditioning apparatus according to Embodiment 3 of the present invention is shown in FIG. FIG. 8 is a sectional view showing the structure of the evaporator 5. In FIG. 7, the reference numerals are the same as those in FIG. In these figures, the evaporator 5 is a plate fin tube type heat exchanger, 12 is a distributor that distributes a refrigerant to a plurality of flow paths existing in the evaporator 5, 13 is a heat transfer tube, and 14 is a heat transfer tube.
Is a fin. Further, the evaporator 5 exchanges heat with the air, and the flow direction of the air is shown by an arrow. The evaporator 5 has a plurality of flow paths in the vertical direction as shown in FIG. The flow of the refrigerant exiting the distributor 12 flows upward in the flow path above the evaporator 5, and flows downward in the flow path below the evaporator 5. When refrigerating machine oil flows into the evaporator 5, most of the refrigerating machine oil is
Since it flows along the wall surface of the pipe, it is difficult to flow upward due to the influence of gravity, and it is easy to flow downward. Therefore, in each flow path of the evaporator 5, a large amount of refrigerating machine oil flows in the lower flow path. When a large amount of refrigerating machine oil flows, the flow velocity of carbon dioxide and the like becomes slow, and the heat transfer performance is lowered in the evaporator in which boiling heat transfer is dominant. Therefore, in the case of the evaporator of FIG. 8, the heat transfer performance is the lowest in the lower flow path.

On the other hand, in the case of boiling heat transfer, when the heat flux is high, the amount of heat transfer is large, and when boiling is more likely to occur, bubbles are frequently generated and the heat transfer performance is improved. In the case of the evaporator of FIG. 8, since the air flows from left to right, the air temperature of the left column is high and the air temperature of the right column is low. Therefore, the left column has a larger temperature difference between the refrigerant and the air, and the left column also has a larger amount of heat transfer, and the heat transfer performance is also improved.

Generally, in a heat exchanger, if there is a portion having extremely low heat transfer performance, the heat transfer performance of the entire heat exchanger is lowered due to the influence of that portion. This is peculiar to the case where the refrigerant exchanges heat with a medium whose temperature changes, such as air.When the heat transfer performance is improved and the amount of heat transfer is increased, the temperature change of the medium occurs accordingly, and the temperature of the refrigerant and the medium changes. However, even if the heat transfer performance is improved, the heat exchange amount does not increase by that amount. Conversely, if the heat transfer performance is deteriorated, the effect directly appears in the heat exchange amount. Therefore, in the heat exchanger, rather than a state where the heat transfer performance is partly good and partly bad,
It is preferable to have uniform heat transfer performance because the amount of heat exchange is increased as a whole.

In the case of the evaporator shown in FIG. 8, since the heat transfer performance of the lower flow passage is low, the lower flow passage has a large amount of heat exchange in the lower flow passage in order to suppress the deterioration of the heat transfer performance. Place a lot in. With such an arrangement, the evaporator 5 as a whole can have uniform heat transfer performance as compared with the case where the respective flow paths are evenly arranged in each of the left and right rows, so that the evaporator 5 as a whole can transfer heat. The thermal performance is improved, and the operation efficiency of the refrigerating and air conditioning system can be improved. That is, in the case of FIG. 8, the distributor 12 distributes the flow path into three channels, each of which is orthogonal to the fin 14.
Although the flow path of the book is provided, the flow path of the bottom system is the flow path orthogonal to the fins 14, and the flow path with low heat transfer performance in which a large amount of refrigerating machine oil flows The number of left columns with a large heat flux is increased to six and the number of right columns with a small heat flux is reduced to two instead of four, thereby improving the heat transfer performance of the flow path of this system. In this way, by bringing the heat transfer performance of the distributed flow paths of the three systems in the direction of equalization, even if the refrigerating machine oil flows into the evaporator 5, the evaporator 5
Improve the heat transfer performance as a whole.

As for the structure of the evaporator 5, even if the number of flow paths and the number of rows are increased and decreased, many lower flow paths are arranged in a row in which the temperature difference between the refrigerant and the air is large, so that the evaporator 5 The heat transfer performance as a whole is improved, and the operation efficiency of the refrigerating and air-conditioning apparatus can be improved. The same effect can be obtained by using a Y-shaped tube, a U-shaped tube, or a header type distributor, which is often used for two branches, as the distributor 12 of the refrigerant flow path. Even when a flat tube is used as the heat transfer tube, the same effect can be obtained with the same arrangement. Although the refrigerating air-conditioning apparatus of this embodiment does not include an oil separator, it may be equipped with an oil separator 4 as in Embodiment 1, and according to the evaporator 5 of this embodiment, Even if refrigerating machine oil is mixed in the refrigerant, the heat transfer performance of the evaporator 5 can be improved.

[0033]

The refrigerating and air-conditioning apparatus according to claim 1 of the present invention is a refrigerating and air-conditioning apparatus in which a compressor, a radiator, a pressure reducing device, and an evaporator are sequentially connected, and oil separation is performed between the pressure reducing device and the evaporator. By installing a heater, you can suppress the decrease in heat transfer performance in the evaporator,
It is possible to obtain a refrigerating air-conditioning system with high operating efficiency.

A refrigerating and air-conditioning apparatus according to claim 2 is
The refrigerating air-conditioning apparatus according to claim 1, wherein a heat exchanger that recovers the cold heat of the separated refrigerating machine oil is provided to suppress a decrease in heat transfer performance in the evaporator and to reduce the amount of liquid refrigerant dissolved in the separated refrigerating machine oil. Since the cooling capacity can be recovered, it is possible to obtain a refrigerating and air-conditioning system with high operating efficiency.

A third aspect of the present invention is a refrigerating and air-conditioning apparatus.
Alternatively, in the refrigerating air-conditioning apparatus of claim 2, since the refrigerant gas is separated together with the refrigerating machine oil in the oil separator and returned to the compressor without passing through the evaporator, the pressure loss in the evaporator can be reduced and the operating efficiency is higher. A refrigerating and air-conditioning system can be obtained.

The refrigerating and air-conditioning apparatus according to claim 4 is
A refrigeration and air-conditioning system in which a compressor, a radiator, a pressure reducing device, and an evaporator are sequentially connected, and a distributor that divides the flow path inside the evaporator into a plurality of flow paths and the flow path that is distributed by the distributor Among these, by arranging many flow paths where the amount of refrigerating machine oil is large at locations with a large heat flux in the heat exchanger, even if refrigerating machine oil flows in, the heat transfer performance of the entire evaporator is improved. It is possible to obtain a refrigerating air-conditioning system with high operating efficiency.

Further, in the refrigerating air-conditioning apparatus of claim 5, in the refrigerating air-conditioning apparatus of claim 4, since the flow path in which the amount of refrigerating machine oil is large flows into the lower part of the evaporator, the entire evaporator is cooled. The heat transfer performance can be improved, and a refrigerating and air-conditioning apparatus with high operating efficiency can be obtained.

The refrigerating air conditioner according to claim 6 of the present invention is the refrigerating air conditioner according to claim 4 or claim 5, wherein a portion having a large heat flux has a difference in temperature between the refrigerant and the heat exchange medium of the heat exchanger. The heat transfer performance of the entire evaporator can be improved and the refrigerating and air-conditioning apparatus with high operating efficiency can be obtained by setting the area where the temperature increases.

The refrigerating air conditioner according to claim 7 is the refrigerating air conditioner according to any one of claims 1 to 6, wherein an expander is provided as a pressure reducing device, so that carbon dioxide, for example, is changed depending on the characteristics of the refrigerant used. It is possible to obtain a refrigerating and air-conditioning apparatus with high operating efficiency that can recover the power at the time of expansion like a refrigerant and can do a part of the compression work and can save the electric input of the compressor.

Further, the refrigerating air conditioner according to claim 8 is the refrigerating air conditioner according to any one of claims 1 to 7, wherein carbon dioxide is used as the refrigerant, so that a refrigerating air conditioner having a high efficiency of dechlorofluorocarbon operation is obtained. be able to.

[Brief description of drawings]

FIG. 1 is a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention.
3 is a diagram showing a refrigerant circuit in FIG.

FIG. 2 is a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention.
It is a figure which shows the structure of the oil separator in FIG.

FIG. 3 is a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention.
It is a figure which shows the structure of another oil separator in FIG.

FIG. 4 is a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention.
It is a figure which shows the structure of another oil separator in FIG.

FIG. 5 is a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention.
It is a figure which shows the structure of another oil separator in FIG.

FIG. 6 is a second embodiment of the refrigeration / air-conditioning system according to the present invention.
3 is a diagram showing a refrigerant circuit in FIG.

FIG. 7 is a third embodiment of the refrigerating and air-conditioning apparatus according to the present invention.
3 is a diagram showing a refrigerant circuit in FIG.

FIG. 8 is a third embodiment of the refrigerating and air-conditioning apparatus according to the present invention.
3 is a cross-sectional view showing the structure of the evaporator in FIG.

FIG. 9 is a diagram showing a refrigerant circuit of a conventional refrigeration / air-conditioning system. 1 compressor, 2 radiator, 3 decompression device (expander), 4
Oil separator, 5 evaporators, 11 heat exchangers, 12 distributors.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F25B 39/02 F25B 39/02 G 43/02 43/02 D (72) Inventor Masayuki Tsunoda 2 Marunouchi, Chiyoda-ku, Tokyo No. 2-3 Sanryo Electric Co., Ltd. (72) Inventor Sou Nomoto 2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Toshihiko Enomoto 2-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Sanryo Electric Co., Ltd. (72) Yoshihisa Kito 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (8)

[Claims] 1. A refrigerating air conditioner in which a compressor, a radiator, a pressure reducing device, and an evaporator are sequentially connected, and an oil separator is provided between the pressure reducing device and the evaporator. 2. The refrigerating air-conditioning apparatus according to claim 1, further comprising a heat exchanger that recovers the cold heat of the separated refrigerating machine oil. 3. The refrigeration air conditioner according to claim 1 or 2, wherein the refrigerant gas is separated together with the refrigerating machine oil in the oil separator and returned to the compressor without passing through the evaporator. 4. A refrigerating and air-conditioning apparatus in which a compressor, a radiator, a pressure reducing device, and an evaporator are sequentially connected to each other, and a distributor for branching a flow path in the evaporator into a plurality of flow paths is provided and distributed by the distributor. A refrigeration / air-conditioning device, characterized in that a large number of flow passages having a large amount of refrigerating machine oil are arranged in a portion having a large heat flux in the heat exchanger. 5. The refrigerating air-conditioning apparatus according to claim 4, wherein the flow passage having a large amount of refrigerating machine oil is a flow passage into the lower portion of the evaporator. 6. The refrigerating and air-conditioning apparatus according to claim 4 or 5, wherein the portion having a large heat flux is a portion where the temperature difference between the refrigerant and the heat exchange medium of the heat exchanger becomes large. 7. The refrigerating and air-conditioning apparatus according to claim 1, further comprising an expander as a pressure reducing device. 8. A refrigerating air-conditioning apparatus according to claim 1, wherein carbon dioxide is used as the refrigerant.