JPH08240363A - Freezing cycle - Google Patents

Abstract

PURPOSE: To prevent a liquid refrigerant of a compressor of a freezing cycle from being sucked in, where the freezing cycle uses a refrigerant taking hydroflurorocarbon as a chief ingredient and freezer oil that has non mutual solubility to the refrigerant or small mutual solubility. CONSTITUTION: There are provided a compressor 1, a condenser 2, an expansion mechanism 3, an evaporator 4, a fan 9 for feeding air to the evaporator 4, a refrigerant taking hydrofluorocarbon as a chief ingredient, freezer oil 7 having no mutual solubility to the refrigerant, a header 5, from a lower part of which a suction piping 10 disposed between the evaporator 4 and the compressor 1 is inserted and to an upper part of which a piping from the evaporator 4 is connected, an oil return hole 8 being provided on an upper side surface of the suction piping 10 in the header 5 and the suction piping 10 is arranged inside the evaporator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating and air-conditioning system using a refrigerant containing hydrofluorocarbon as a main component.

[0002]

2. Description of the Related Art A conventional refrigeration cycle using HFC134a, which is a hydrofluorocarbon, as a refrigerant is disclosed in Japanese Patent Laid-Open No. 5-157379.

A conventional refrigeration cycle will be described with reference to the drawings. 1 is a compressor, 2 is a condenser for condensing the refrigerant gas discharged from the compressor, 3 is a capillary tube as an expansion mechanism, 4 is an evaporator, 5 is an outlet side of the evaporator 4 connected to the upper side. , A header connecting the suction side of the compressor 1 to the lower side, 6 is a suction pipe inserted into the header 5 from the lower side of the header 5 and extending upward, 7 is refrigerating machine oil that lubricates sliding parts in the compressor, A refrigerating machine oil such as hard alkylbenzene oil, soft alkylbenzene oil having excellent low-temperature fluidity, polyalphaolefin, paraffinic mineral oil, and naphthene mineral oil, which are used alone or in combination, and are compatible with a refrigerant such as HFC134a containing hydrofluorocarbon as a main component. Some are insoluble or less soluble. 8 is header 5
It is an oil return hole provided on the upper side surface of the suction pipe 6 inserted therein.

Next, the operation will be described. The refrigerant discharged from the compressor 1 is condensed in the condenser 2, expanded under reduced pressure in the capillary tube 3, evaporated in the evaporator 4, and the refrigerant that cannot be completely evaporated in the evaporator 4 is stored in the header 5. ,
Only the gas phase component is sucked into the compressor 1 through the suction pipe 6. At this time, the refrigerating machine oil 7 is discharged from the compressor 1 together with the refrigerant, flows in the pipe, and reaches the evaporator 4.

The refrigerating machine oil 7 flows in the evaporator 4 together with the refrigerant that evaporates and vaporizes, and enters the header 5 or is stored in the header together with the liquid refrigerant stored therein. here,
Since the specific gravity of the refrigerating machine oil 7 is lighter than that of the liquid refrigerant and there is no mutual solubility with the refrigerant, the refrigerant and the refrigerating machine oil 7 are separated into two phases, and the refrigerating machine oil 7 floats on the liquid refrigerant.

When the liquid level of the refrigerating machine oil 7 reaches the oil return hole 8, the refrigerating machine oil 7 is sucked into the suction pipe 6 through the oil return hole 8 and is sucked into the compressor 1.

[0007]

However, in the above conventional configuration, when the load on the evaporator 4 is extremely small,
There is a risk that the liquid refrigerant stored in the header 5 becomes excessive, the liquid refrigerant is sucked together with the refrigerating machine oil 7, and liquid compression occurs in the compressor 1.

Further, when the compressor 1 is stopped, the refrigerant is condensed and liquefied in the element having the lowest temperature, so that the evaporator 4 is stopped during the stop.
The refrigerant accumulated in the header 5 is sucked into the suction pipe 6 at the same time when the compressor 1 is started, and is sucked into the compressor 1 again to cause liquid compression, which is a big problem in the life and reliability of the compressor. there were.

[0009]

Therefore, the refrigeration cycle of the present invention comprises a compressor, a condenser, an expansion mechanism, an evaporator, and
A refrigeration cycle in which these are sequentially connected in a ring, a blower for blowing air to the evaporator, a refrigerant containing hydrofluorocarbon as a main component, refrigerating machine oil having no or little mutual solubility with the refrigerant, and the evaporator. A header which is installed between compressors and which is a suction pipe that is a pipe from the compressor is connected to the lower part, a pipe from the evaporator is connected to the upper part, a suction pipe which is inserted from the lower part of the header, and a suction pipe in the header. The oil return hole provided on the upper side surface and the suction pipe were arranged in the evaporator, and then connected to the compressor.

Further, a compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in a ring, a blower for blowing air to the evaporator, and hydrofluorocarbon as a main component. Refrigerant, refrigerating machine oil having no or little mutual solubility with the refrigerant, a header installed between the evaporator and the compressor, the pipe from the compressor is connected to the upper part, and the pipe from the evaporator is connected to the lower part, and The oil return pipe inserted from the lower part of the header and the oil return pipe were connected to the windward path of the evaporator, and were connected to the suction pipe which is a pipe between the header and the compressor.

Further, an orifice is provided in the suction pipe portion to which the oil return pipe is connected.

[0012]

With the above construction, in the refrigeration cycle of the present invention, the liquid refrigerant flowing out from the header to the suction pipe together with the refrigeration oil is evaporated again in the evaporator, so that the refrigerant does not reach the compressor.

Further, the refrigerant in the header is made to flow from the bottom to the top, only the refrigerant vapor is made to flow into the suction pipe, and the refrigerating machine oil separated into two phases above the liquid refrigerant in the header is led out by the oil return pipe, Furthermore, by disposing an oil return pipe inside the evaporator to evaporate the liquid refrigerant that has flown out together with the refrigerating machine oil, and by joining it with the suction piping, gas-liquid separation of the refrigerant and conversion of the refrigerating machine oil into a compressor can be performed. It was compatible.

Further, a negative static pressure is generated at the orifice provided at the oil return pipe connecting portion of the suction pipe to promote the flow of the refrigerating machine oil from the oil returning pipe, thereby ensuring the return of the refrigerating machine oil to the compressor. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1. The same components as those of the prior art will be designated by the same reference numerals and detailed description thereof will be omitted.

A blower 9 is installed in the vicinity of the evaporator 4 and supplies the air, which is heat-exchanged by the evaporator 4, to the evaporator 4. Reference numeral 10 denotes a suction pipe A, which has a heat exchange portion 10a provided at the most upstream position of the air flowing through the evaporator 4.

Next, the operation will be described. In the header 5, the refrigerating machine oil 7 contains HFC134a which has no mutual solubility.
It is separated into two phases from the refrigerant mainly composed of hydrofluorocarbon and stays on the refrigerant. When the oil level in the header 5 of the refrigerating machine oil 7 reaches the position of the oil return hole 8, it flows into the suction pipe A10 through the oil return hole 8.

At this time, the load on the evaporator 4 is reduced,
Further, when the lowest temperature point during the stop is concentrated and the refrigerant liquid level in the header 5 rises, the position of the oil return hole 8 passes through the layer of the refrigerating machine oil 7 and becomes the refrigerant layer. ,
The liquid refrigerant flows into the suction pipe A10.

The liquid refrigerant flowing out of the header 5 through the oil return hole 8 is a heat exchange section 10a which is a part of the suction pipe.
Pass through.

At this time, in the heat exchange section 10a, the evaporator 4 is
Since it is installed at the most upstream part, which is the inlet of the air supplied from the blower 9, the heat is exchanged with the air having the highest temperature. Therefore, the liquid refrigerant, or the liquid refrigerant mixed with the refrigerating machine oil 7 and flowing in, is evaporated and vaporized by heat exchange.

Therefore, in the suction pipe A10, only the vaporized refrigerant vapor and the refrigerating machine oil 7 are sucked into the compressor 1.

Next, a second embodiment will be described with reference to FIG. Reference numeral 11 is a header, 12 is a suction pipe B, 13 is an oil return pipe, and 13a is a part of the oil return pipe 13, which is arranged at the most upstream position of the air flow of the evaporator 4. Reference numeral 14 is a confluence portion of the suction pipe B12 and the oil return pipe 13. 15 is an evaporator 4
And an outlet pipe for connecting the header 11 with the header 11.

The suction pipe B12 is connected to the upper part of the header 11. Further, the evaporator outlet pipe 15 is connected to the header 11
It is inserted into the header 11 from the lower part of. The evaporator outlet pipe 15 is inserted up to the top of the header 11. The oil return pipe 13 is inserted into the header 11 similarly to the evaporator outlet pipe 15, but its tip position is at the end of the evaporator outlet pipe 1.
5 It is located below the tip.

Next, the operation will be described. Header 11
Has configured the flow from bottom to top, so
Only the gas phase component of the refrigerant flows into the suction pipe B12 attached to the upper part of the header 11, and the liquid refrigerant that cannot be evaporated in the evaporator 4 stays in the header 11. At the same time, the refrigeration oil 7 discharged from the compressor 1 and circulating together with the refrigerant also stays in the header 11. The refrigerating machine oil 7 has no mutual solubility or a small mutual solubility with the refrigerant, and thus is separated into two phases. As a result, the refrigerating machine oil 7 stays in a layer on the liquid refrigerant.

When the layer of the refrigerating machine oil 7 reaches the tip of the oil return pipe 13, the refrigerating machine oil 7 flows out of the header 11 through the oil return pipe 13. Further, when the refrigerant stays and the boundary layer between the refrigerating machine oil 7 and the refrigerant reaches the tip of the oil return pipe 13,
When the mixture of the refrigerant and the refrigerating machine oil 7 further accumulates, the liquid refrigerant only flows out from the oil return pipe 13.

The liquid refrigerant flowing out from the oil return pipe 13 is
It reaches the heat exchange section 13a of the oil return pipe 13 provided in the evaporator 4. Since the heat exchanging portion 13a is provided at the air-side inlet of the evaporator 4, it exchanges heat with the air having the highest temperature, and the liquid refrigerant is all vaporized and vaporized into only the vapor phase. After that, the oil return pipe 13 is connected to the suction pipe B at the merging portion 14.
12, and the refrigerant vapor and the refrigerating machine oil 7 are returned to the compressor 1.

Next, a third embodiment will be described. 16
Is an orifice provided in the confluent portion 14 of the suction pipe B12 and the oil return pipe 13.

Next, the operation will be described. Header 11
The suction pipe B12 and the oil return pipe 13, which are the outlets of the, are parallel pipes. Normally, for the suction pipe B12, a pipe having an inner diameter as large as possible is used in order to prevent a decrease in efficiency due to pressure loss.

Further, since the oil return pipe 12 is essentially required to pass only the refrigerating machine oil 7 whose circulation amount is extremely smaller than that of the refrigerant, a thin pipe can be used.

Therefore, of course, the flow rate of the oil return pipe 7 is small and the flow velocity is slow, so that oil may stay in the oil return pipe 13. At this time, when the velocity of the refrigerant flow in the suction pipe B12 is increased by the orifice provided in the confluence part 14 of both, a negative static pressure is generated in the oil return pipe 13 opening to the center of the orifice according to Bernoulli's law.

As a result, the refrigerating machine oil 7 in the oil return pipe 13 is
Of the refrigerating machine oil 7 flowing through the oil return pipe 13
Is atomized at the orifice 16 and is sucked into the compressor 1 together with the refrigerant vapor.

[0032]

As is apparent from the above description, the refrigeration cycle of the present invention comprises a compressor, a condenser, an expansion mechanism, an evaporator, and a refrigeration cycle in which these are sequentially connected in an annular shape. A blower for blowing air to the evaporator, a refrigerant containing hydrofluorocarbon as a main component, refrigerating machine oil having no or little mutual solubility with the refrigerant, and a pipe from the compressor installed between the evaporator and the compressor. A header having a suction pipe connected to the lower part and a pipe from the evaporator connected to the upper part, a suction pipe inserted from the lower part of the header, an oil return hole provided on a side surface above the suction pipe in the header, and the suction pipe. Since it was connected to the compressor after it was installed in the evaporator, the liquid refrigerant that could not be stored in the header and flowed out to the suction pipe is evaporated and vaporized again by heat exchange. Eliminated, it is possible to prevent the liquid compression of the reliability significant problem in advance.

Further, a compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in an annular shape, a blower for blowing air to the evaporator, and hydrofluorocarbon as a main component. Refrigerant, refrigerating machine oil having no or little mutual solubility with the refrigerant, a header installed between the evaporator and the compressor, the pipe from the compressor is connected to the upper part, and the pipe from the evaporator is connected to the lower part, and The oil return pipe inserted from the lower part of the header and the oil return pipe were connected to the windward path of the evaporator, and were connected to the suction pipe which is a pipe between the header and the compressor.

Therefore, the refrigerant vapor and the liquid refrigerant are separated from the header, and only the refrigerant vapor is allowed to flow in the suction pipe,
Further, the two-phase separated refrigerating machine oil flows out of the header through the oil return pipe, and the mixed and flowing liquid refrigerant is also evaporated and vaporized in the heat exchange section provided in the evaporator and then joined with the suction pipe. Therefore, only the refrigerant vapor is sucked into the compressor, and it is possible to prevent liquid compression which is a serious problem in reliability.

Further, since the orifice is provided in the suction pipe portion to which the oil return pipe is connected, the refrigerating machine oil that tends to stay in the oil return pipe is sucked into the suction pipe by the negative static pressure generated in the orifice portion. Therefore, due to insufficient oil return, abrasion due to insufficient lubrication of sliding parts in the compressor does not occur, which has a great effect on reliability.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of a first embodiment of the present invention.

FIG. 2 is a refrigeration cycle diagram of a second embodiment of the present invention.

FIG. 3 is a sectional view of a confluence portion of a third embodiment of the present invention.

[Fig. 4] Conventional refrigeration cycle diagram

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Capillary tube 4 Evaporator 5 Header 7 Refrigerator oil 9 Blower 10 Suction pipe A 11 Header 12 Suction pipe B 13 Oil return pipe 16 Orifice

Claims (3)

[Claims] 1. A compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in a ring, a blower for blowing air to the evaporator, and a hydrofluorocarbon as a main component. Refrigerant, refrigerating machine oil having no or little mutual solubility with the refrigerant, installed between the evaporator and the compressor, the suction pipe which is the pipe from the compressor was connected to the lower part, and the pipe from the evaporator was connected to the upper part. After the header, the suction pipe inserted from the lower part of the header, the oil return hole provided on the upper side surface of the suction pipe in the header, and the suction pipe in the evaporator, the compressor is installed in the compressor. Refrigeration cycle connected. 2. A compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in a ring, a blower for blowing air to the evaporator, and a hydrofluorocarbon as a main component. Refrigerant, refrigerating machine oil having no or little mutual solubility with the refrigerant, a header installed between the evaporator and the compressor, the pipe from the compressor is connected to the upper part, and the pipe from the evaporator is connected to the lower part, and A refrigeration cycle in which an oil return pipe inserted from the lower part of the header and the oil return pipe are arranged in the evaporator and connected to a suction pipe which is a pipe between the header and the compressor. 3. The refrigeration cycle according to claim 2, wherein an orifice is provided in a suction pipe portion connecting the oil return pipe.