JP2001040340A - Binary refrigerating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide refrigerating equipment that can realize a desired refrigeration capacity and nonproblematic in oil sludge formation and oil deterioration by using a refrigerant composition prepared by adding a specified amount of n-pentane or propane to an azeotrope prepared by mixing trifluoromethane with hexafluoroethane in a specified ratio in the low-temperature-side cooling circuit. SOLUTION: A refrigerant composition is a mixture comprising (A) an azeotrope being a mixture of 39 wt.% trifluoromethane having a specific heat ratio of 1.22 with 61 wt.% hexafluoroethane having a specific heat ratio of 1.09 and having an azeotropic point of about -88 deg.C and at most 14 wt.%, based on component A, (B) n-pentane or propane. Although component A is poorly miscible with an oil, the refrigerant composition is returned to the compressor while it is in the state in which the oil is dissolved in component B. In a binary refrigerating equipment provided with a high-temperature-side cooling circuit and a low-temperature-side cooling circuit and performing cooling by the refrigerant passing the cascade condenser in the low-temperature-side refrigerant, the refrigerant composition is sealed in the low-temperature-side cooling circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant composition used in a refrigeration system and having a low risk of destruction of the ozone layer.
It relates to a binary refrigeration system using the same.

[0002]

2. Description of the Related Art Conventionally, R12 (dichlorodifluoromethane) and R5
00 (azeotropic mixture of R12 and R152a (1,1-difluoroethane)). The boiling point of R12 is about -30
At 500C, the boiling point of R500 is about -33C, which is suitable for ordinary refrigeration equipment. Furthermore, even if the suction temperature into the compressor is relatively high, the discharge temperature will not be so high as to cause oil sludge in the compressor. Further, R12 has good compatibility with the oil of the compressor and plays a role of drawing the oil in the refrigerant circuit back to the compressor.

[0003] On the other hand, in order to obtain a lower temperature range of -80 ° C or lower, R503 (azeotropic mixture of R23 and R13) is used. R503 has a boiling point of -88.65 ° C.
And is optimal for obtaining low temperatures.

[0004]

However, it is said that each of the above refrigerants may destroy the ozone layer, and the use of the refrigerant has been restricted. That is, R that composes R500
It has been elucidated that R13 comprising R12 and R503 is a so-called regulated refrigerant which is hardly decomposable, and has a risk of destroying the ozone layer when it is released into the atmosphere and reaches the ozone layer.

At present, researchers around the world are researching and searching for alternative refrigerants to the above-mentioned restricted refrigerants.

The present invention has been made in view of the above points, and can achieve a low temperature of -80 ° C. without using a regulated refrigerant having a high risk of destruction of the ozone layer. It is an object of the present invention to provide a refrigerant composition that can be used as an alternative refrigerant to a refrigeration system, and to provide a binary refrigeration apparatus that can actually achieve low temperatures.

[0007]

According to the present invention, there is provided a refrigerant composition comprising an azeotropic mixture of trifluoromethane and hexafluoroethane.

Further, as claimed in claim 2, the azeotropic mixture comprises a mixture of an azeotropic mixture of trifluoromethane and hexafluoroethane and n-pentane, and n-pentane is added in an amount of 14 to the total weight of trifluoromethane and hexafluoroethane. %
A refrigerant composition was prepared by mixing the following ratios.

[0009] According to a third aspect of the present invention, there is provided an azeotropic mixture of trifluoromethane and hexafluoroethane and a mixture of propane, wherein propane is contained in a proportion of 14% or less based on the total weight of trifluoromethane and hexafluoroethane. To form a refrigerant composition.

Further, a high temperature side refrigerant circuit and a low temperature side refrigerant circuit are provided, and the refrigerant in the low temperature side refrigerant circuit is condensed by the refrigerant passing through a cascade condenser in the high temperature side refrigerant circuit. In the original refrigerating apparatus, the refrigerant sealed in the low-temperature side refrigerant circuit is a mixture of azeotropic mixture of trifluoromethane and hexafluoroethane, and n-pentane or propane, and n-pentane or propane is mixed with trifluoromethane and hexane. This is a binary refrigeration apparatus using a refrigerant composition mixed at a ratio of 14% or less based on the total weight of fluoroethane.

[0011]

According to the structure of the first aspect, trifluoromethane (R23) is an HFC containing no chlorine, and hexafluoroethane (R116) is an FFC composed of only fluorine and carbon.
C, none of which is subject to regulation on the problem of ozone depletion, and its boiling point is -82.5 ° C for trifluoromethane (R23) and -78.5 for hexafluoroethane (R116). ° C, azeotropic point -88
Since the temperature is about ℃, the refrigeration ability can be sufficiently exhibited as a substitute refrigerant for R503.

Since the specific heat ratio of trifluoromethane (R23) is slightly higher at 1.22, there is a concern that the discharge temperature will increase when the trifluoromethane (R23) is sealed in a refrigerant circuit. Hexafluoroethane (R1
Since 16) is mixed in a predetermined amount, an increase in the discharge temperature can be suppressed. As a result, a desired refrigeration capacity can be realized, and deterioration of oil sludge and oil can be suppressed.

Further, the azeotropic mixture of trifluoromethane (R23) and hexafluoroethane (R116) has poor compatibility with oil. To solve this problem, an oil separator is provided in the refrigerant circuit, and the separator is completely used. The problem can be solved by separating the oil to the compressor and returning to the compressor.

According to the second aspect of the present invention, it is possible to provide a refrigerant composition which returns oil to the compressor without completely separating the oil particularly by the oil separator. That is, n
−Pentane has a high boiling point of + 36.07 ° C., but has good compatibility with the oil of the compressor, and is mixed with a predetermined amount of n-pentane to dissolve the oil in n-pentane. Can be returned, and the adverse effects such as lock due to oil rising of the compressor can be prevented. here,
Since n-pentane has a high boiling point, if it is mixed in too much, the evaporation temperature rises and the desired low temperature cannot be obtained. Therefore, by mixing n-pentane at a ratio of 14% by weight or less, the oil can be returned to the compressor without increasing the evaporation temperature.

According to the third aspect of the present invention, it is possible to obtain a refrigerant composition that returns the oil to the compressor without completely separating the oil by the oil separator. That is, propane also has good compatibility with the oil of the compressor, and by mixing propane in a predetermined amount, the oil can be returned to the compressor in a state where the oil is dissolved in the propane, and the propane oil rises. Evils such as locking can be prevented. Here, propane has a low boiling point of −42.75 ° C. and thus has little effect on the evaporation temperature. However, since it is flammable, there is a danger of explosion and handling is difficult. However, by setting the mixing ratio of propane to 14% or less, propane can be maintained in a non-combustible region, and there is no fear of explosion and the like. Therefore, by mixing propane at a ratio of 14% by weight or less, oil can be returned to the compressor while preventing danger such as explosion.

According to the fourth aspect of the present invention, in the actual refrigerant circuit, the oil return can be made good and a low temperature of about -83 ° C. can be achieved in the evaporator without danger of explosion. It can be put to practical use as a medical freezer for blood cooling etc. without using.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a refrigerant circuit diagram of a binary refrigeration apparatus in which the refrigerant composition of the present invention is sealed. S1 represents the high-temperature side refrigerant cycle, and S1
2 indicates a low-temperature side refrigerant cycle.

A discharge side pipe 2 of the compressor 1 constituting the high temperature side refrigerant cycle S1 is connected to an auxiliary condenser 3, and the auxiliary condenser 3 is an oil cooler 4, an auxiliary condenser 5, and a low temperature side refrigerant cycle of the compressor 1. Oil cooler 7, condenser 8, dryer 9, and capillary tube 1 of compressor 6 constituting S2
0, sequentially connected to the cascade capacitor 11,
It is connected to the compressor 1 via a suction pipe 13 via a liquid receiver 12. 14 is a cooling fan for each of the condensers 3, 5 and 8.

The discharge pipe 15 of the compressor 6 of the low-temperature side refrigerant cycle S2 is connected to an oil separator 16, and the separated compressor oil is returned to the compressor 6 through a return pipe 17. On the other hand, the refrigerant flows into the pipe 18 and exchanges heat with the suction-side heat exchanger 19, then passes through the pipe 20 in the cascade condenser 11, condenses, and is dried.
1. The heat exchanger 1 flows into the evaporator 24 from the inlet pipe 23 via the capillary tube 2 and exits from the outlet pipe 25.
This is a configuration that returns to the compressor 6 from the suction side pipe 26 of the compressor 6 via the compressor 9. Reference numeral 27 denotes an expansion tank, which is connected to a suction side pipe 26 via a capillary tube 28.

In the high-temperature side refrigerant cycle S1, R22 (chlorodifluoromethane, CHCLF ₂ ) is sealed.
The boiling point of R22 is −40.75 ° C. at atmospheric pressure.
22 is condensed in each of the condensers 3, 5 and 8, and is decompressed in the capillary tube 10 and
And evaporates. Here, the cascade capacitor 1
1 is about −40 ° C.

An azeotropic mixture of R23 (trifluoromethane, CHF ₃ ), R116 (hexafluoroethane, C ₂ F ₆ ) and n-pentane (C ₅ H ₁₂ ) is sealed in the low-temperature side refrigerant cycle S2. . Here, the mixing ratio of R23 and R116 is 39:61, and n-pentane is
The composition is mixed at a ratio of 14% or less to the total weight of R23 and R116. As a result, a refrigerant composition having a considerably low azeotropic point of −88 ° C. is sealed. And the refrigerant and compressor oil discharged from the compressor 6 are:
It flows into the oil separator 16. Then, the oil is separated into a gaseous phase portion and a liquid phase portion, and most of the oil is in a liquid phase. The gas-phase refrigerant and oil exchange heat with the suction-side heat exchanger 19 through the pipe 18, and are further cooled and condensed by the cascade condenser 11 by evaporation of the refrigerant in the high-temperature side refrigerant cycle S1. Thereafter, the pressure is reduced by the capillary tube 22, and then flows into the evaporator 24 to evaporate. This evaporator 24
Is mounted on a wall of a freezer (not shown) in a heat exchange relationship to cool the inside of the refrigerator. Here, the evaporation temperature in the evaporator 24 reaches −88 ° C.

In the binary refrigeration system configured as described above, trifluoromethane (R23), which is a refrigerant composition sealed in the low-temperature side refrigerant cycle S2, contains chlorine-free H.
Hexafluoroethane (R116) is an FC that consists only of fluorine and carbon, and is not subject to regulations on the problem of ozone depletion, and its boiling point is trifluoromethane (R23). -82.5
° C, hexafluoroethane (R116) is -78.5 ° C
And the azeotropic point is about -88 ° C,
As an alternative refrigerant of No. 3, it can sufficiently exhibit refrigeration capacity.

Since the specific heat ratio of trifluoromethane (R23) is slightly higher at 1.22, there is a concern that the discharge temperature will rise in the refrigerant circuit.
Hexafluoroethane (R116), which is considerably lower than 9,
Since 1% by weight is mixed, an increase in the discharge temperature can be suppressed. As a result, a desired refrigeration capacity can be realized, and deterioration of oil sludge and oil can be suppressed.

Here, the value of the specific heat ratio K (Cp / Cv) has a great effect on the discharge gas temperature of the compressor in adiabatic compression as shown by the following equation (1), and the molecular weight of the composition is Larger values indicate smaller values.

[0025]

(Equation 1)

Furthermore, the azeotropic mixture of trifluoromethane (R23) and hexafluoroethane (R116) has poor compatibility with oil, but can be solved by mixing n-pentane at 14% by weight or less. That is, n-pentane has a high boiling point of + 36.07 ° C., but has good compatibility with compressor oil, and the oil is dissolved in n-pentane by mixing n-pentane in a range of 14% by weight. In this state, the compressor can be returned to the compressor, so that it is possible to prevent a problem such as lock caused by oil rising of the compressor. As a result, the oil can be returned to the compressor 6 without completely separating the oil by the oil separator 16. Here, since n-pentane has a high boiling point, if it is mixed in too much, the evaporation temperature rises and the desired low temperature cannot be obtained. However, by mixing n-pentane at a ratio of 14% by weight or less, The oil can be returned to the compressor without increasing the evaporation temperature and while maintaining the n-pentane in the non-combustible region.

As described above, according to the binary refrigerating apparatus of the present embodiment, it is possible to achieve a low temperature of about -88 ° C. in the evaporator without causing a danger of explosion or the like, with good oil return. It can be put to practical use as a medical freezer for blood cooling etc. without using a regulated refrigerant.

Also, since n-pentane is not produced in a factory, it can be easily obtained when used in a freezer or the like.
It is practical.

Trifluoromethane (R23);
Hexafluoroethane (R116) and propane
Since both are in the gas state, the workability and serviceability of the sealing can be achieved at the factory.

In this embodiment, trifluoromethane (R
23), a mixture of hexafluoroethane (R116) and n-pentane has been described, but the same effect can be obtained by mixing R290 (propane, C ₃ H ₈ ) in the same ratio instead of n-pentane. can get. That is, propane also has good compatibility with the compressor oil. By mixing propane at 14% by weight, the propane can be returned to the compressor 6 in a state where the oil is dissolved in the propane. It is possible to prevent adverse effects such as locking due to rising. Here, propane has a low boiling point of −42.75 ° C. and thus has little effect on the evaporation temperature, but since it is flammable, there is a danger of explosion and handling is difficult. However, by setting the mixing ratio of propane to 14% by weight or less, propane can be maintained in a nonflammable region, and there is no fear of explosion or the like.

[0031]

As described above, according to the present invention, trifluoromethane (R23) is an HFC containing no chlorine,
Hexafluoroethane (R116) is an FC comprising only fluorine and carbon, none of which is subject to regulation on the problem of depletion of the ozone layer, and its boiling point is -82.5% for trifluoromethane (R23). ° C, hexafluoroethane (R116) is as low as -78.5 ° C, and the azeotropic point is about -88 ° C, so that it can sufficiently exhibit refrigeration ability as a substitute refrigerant for R503.

Since the specific heat ratio of trifluoromethane (R23) is slightly higher at 1.22, there is a concern that the discharge temperature will increase when the trifluoromethane (R23) is sealed in a refrigerant circuit. Hexafluoroethane (R1
Since 16) is mixed in a predetermined amount, an increase in the discharge temperature can be suppressed. As a result, when sealed in a refrigeration apparatus, desired refrigeration capacity can be achieved, and deterioration of oil sludge and oil can be suppressed.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a binary refrigeration apparatus in which a refrigerant composition of the present invention is sealed.

[Explanation of symbols]

 S1 High-temperature side refrigerant cycle S2 Low-temperature side refrigerant cycle 1,6 Compressor 11 Cascade condenser 24 Evaporator

Claims (1)

[Claims] 1. A binary refrigeration apparatus comprising a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit, wherein condensation of refrigerant in the low-temperature side refrigerant circuit is performed by refrigerant passing through a cascade condenser in the high-temperature side refrigerant circuit. The refrigerant sealed in the low-temperature side refrigerant circuit was replaced with trifluoromethane with a higher specific heat ratio.
9% by weight of hexafluoroethane having a lower specific heat ratio
% Of an azeotrope and n-pentane or propane, and the n-pentane or propane is
A binary refrigeration apparatus using a refrigerant composition obtained by mixing trifluoromethane and hexafluoroethane at a ratio of 14% or less based on the total weight.