JP2009102567A - Non-azeotropic refrigerant for ultra-low temperature service - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ternary non-azeotropic refrigerant for ultra-low temperature service capable of offering service smoothly and stably without reconstructing the refrigerant circulation line of a conventional single-step type refrigerating system for ultra-low temperature service (unitary refrigeration circuit). <P>SOLUTION: The non-azeotropic refrigerant for ultra-low temperature service for use in a single-step type refrigerating system contains a high boiling point gas (boiling point at Tb1), a low boiling point gas (boiling point at Tb2), and an ultra-low boiling point gas (boiling point at Tb3), wherein the boiling points of three sorts of gases meet the condition -273°C≤Tb3≤-130°C<Tb2<-20°C≤Tb1≤+60°C, characterized by that the gas mixing by-weight composition proportion is set so that the dew point in the high pressure environment is at the room temperature or above and the boiling point is higher than the dew point in the low pressure environment. The invention allows enhancing the refrigerating ability effectively while the amount of fluorocarbon being used as refrigerant is made zero, and also assures an extraordinary small ill influence on the environment such as the green house effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention uses a non-azeotropic refrigerant mixture and utilizes the characteristics of the non-azeotropic refrigerant, at a room temperature (immediately, ambient temperature in a single-stage refrigeration system operation state) environment, a single compressor, condenser And a system capable of operating a low temperature of -40 ° C or lower, particularly an ultralow temperature of -60 ° C or lower. The present invention relates to a non-azeotropic refrigerant for ultra-low temperature, which makes it possible to achieve an ultra-low temperature by using a hydrocarbon-based refrigerant gas or a fluorocarbon containing no chlorine.

Conventionally, fluorocarbons, so-called chlorofluorocarbons, have been widely used as refrigerants for freezers and refrigerators.
However, because of concerns and concerns that chlorofluorocarbons (specific chlorofluorocarbons) in the chemical structural formula will destroy the ozone layer in the upper atmosphere layer and form ozone holes, the so-called Montreal Protocol (substance that destroys the ozone layer) The Montreal Protocol) was adopted in 1987, and the so-called ozone layer protection law (the law concerning the protection of the ozone layer by the regulation of specific substances) was enacted in 1988 under the domestic legislation.

From such a legal background, after the legislation has been established, the development of a hydrocarbon-based refrigerant that does not have chlorine in its chemical structural formula or as an alternative to a fluorocarbon-based refrigerant has been promoted.
However, even chlorofluorocarbons that do not contain chlorine in their chemical structural formulas have a high absorption capacity for long-wavelength infrared rays (heat rays) and have a so-called greenhouse effect (an effect of warming the global environment). Is inherent.

From such a technical background, it has been desired to select a material with a small greenhouse effect or to develop a technology that reduces the amount of a material with a large greenhouse effect. Searching for a gas that satisfies the characteristics of a predetermined refrigerant is being conducted.
However, it has been difficult to satisfy performances equivalent to various performances as a refrigerant possessed by conventional specific chlorofluorocarbons using only a single low-boiling hydrocarbon gas.

In view of this, research and development have been eagerly promoted to bring close to various performances as refrigerants possessed by conventional specific chlorofluorocarbons by mixing two or more kinds of low-boiling hydrocarbon gases.
As such a mixed refrigerant composed of two or more kinds of low-boiling hydrocarbon gases, an azeotropic refrigerant having a constant boiling point is desirable as in the conventional single component refrigerant gas.
However, the combination of the types of low-boiling hydrocarbon gases and the composition ratio conditions for realizing an azeotropic refrigerant are limited to extremely narrow conditions, and in most conditions outside these conditions, Even when two or more kinds of low boiling hydrocarbon gases are mixed, non-azeotropic characteristics are exhibited.

These non-azeotropic refrigerants (refrigerants made by mixing two or more low-boiling hydrocarbon gases that exhibit non-azeotropic characteristics) are different from single-component refrigerants and azeotropic refrigerants. However, since the boiling point and the dew point are inconsistent, the liquid phase and the gas phase can be obtained. Under the conditions where the phases coexist, the composition of the gas phase and the liquefied condensed phase differ, and in the condensation process, there is a phenomenon that condensation does not occur at a constant temperature and pressure, which hinders stable operation of the refrigeration system. There was a problem of coming.

The problem that the boiling point and dew point of non-azeotropic refrigerants (refrigerants made by mixing two or more low-boiling hydrocarbon gases that exhibit non-azeotropic characteristics) are inconsistent, that is, the liquid phase (condensed phase). Under the conditions where the gas phase and the gas phase (gas phase) coexist, the composition of the two phases is different, so the phenomenon of condensation at a pinpoint temperature and pressure during the condensation process occurs, which hinders stable operation of the refrigeration system. The conventional technology that makes the problem of coming the solution is shown below.

[Patent Document 1]
In Japanese Patent Application Laid-Open No. 61-83258 (Japanese Patent Publication No. 5-025912), in a refrigeration system using a non-azeotropic refrigerant, based on the relationship between the evaporation pressure of the non-azeotropic refrigerant mixture and the corresponding saturation temperature. In addition to controlling the temperature and pressure in the refrigeration system via the expansion valve, the warning means is activated when these control conditions fall outside a certain range. Especially in the latter, the process from the evaporator to the compressor is performed. It is disclosed that heat exchange is performed between a low-temperature suction refrigerant and a high-pressure refrigerant from a compressor to an evaporator.
That is, the combination of the component refrigerants used is a low boiling point R-22 and a high boiling point refrigerant R-114, and the normal boiling points are −40.8 ° C. and 3.85 ° C., respectively. The difference between the specific dew point and boiling point is large, which causes problems such as refrigerant suction in the liquid phase in the compressor, and avoids such a state by controlling the refrigerator system. .

[Patent Document 2]
In JP-A-8-166172, the refrigerant component disclosed in the examples is a non-azeotropic refrigerant mixture composed of fluorocarbon, that is, R-32 (standard boiling point: −51.7 ° C.), R-125 ( Standard boiling point: −48.5 ° C.) and R-134a (standard boiling point: −26.5 ° C. F). The standard boiling points of the fluorocarbons constituting this non-azeotropic refrigerant mixture are all significantly lower than the normal temperature (0 to 40 ° C.) under normal atmospheric pressure, and must be below the normal boiling point under standard atmospheric pressure. It will not liquefy.
Therefore, a compressor, a condenser, a receiver, a decompressor, and an evaporator are provided, and a heat exchanger that exchanges heat between the refrigerant that flows from the condenser to the receiver and the refrigerant that flows from the evaporator to the compressor is provided. Employing a refrigeration system is disclosed.
Regarding refrigerants, the problem of the problem is solved by reducing the difference in boiling point (difference between dew point and boiling point as a mixed refrigerant).
Regarding the refrigeration system, in the state where the gas phase and the liquid phase coexist, only the liquefied non-azeotropic refrigerant is separated by the receiver and sent to the evaporator, and the refrigerant gas entering the compressor is in the liquid state refrigerant In order to prevent liquid from being compressed due to the mixing of gas, it is disclosed that a mechanism of performing gas-liquid separation also in the suction pipe is disclosed.
However, the system that adopts the corner also has a complicated configuration, so that not only maintenance, maintenance, and repair require time, labor, and expense, but also in daily operation, the gas and liquid can coexist in the gas phase. This makes it difficult to control a non-azeotropic solvent having different characteristics of the liquid phase composition to return to a stable steady state.

[Patent Document 3]
Japanese Patent No. 3571296 includes trifluoromethane (CHF3: R-23) and perfluoroethane (C2: F6: R-116), and at least one of propane and butane. The ultra-low temperature mixed refrigerant is disclosed in which the mixing ratio of R-23 is 70 to 15 wt% and R-116 is 30 to 85 wt%.
The mixed refrigerant can be used without adversely affecting the environment because the ozone depletion ability is zero and the warming effect is low. It can be produced at low cost from R-23 and R-116, propane and butane gas, and is safe and easy to handle.
Due to the characteristics of the mixed refrigerant, it is not necessary to build a new complex and advanced refrigerator unit, and it is possible to replace the specified CFC refrigerant in the existing freezer with the mixed refrigerant and continue to use it as it is. Yes, it is possible to realize an ultra-low temperature, in particular, an internal temperature of −60 ° C. or lower.
The equipment is extremely inexpensive and easy to maintain.
Since ultra-low temperature can be realized, it is expected to expand into biotechnology, which is expected to develop in the future, as well as food and other fields.

[Patent Document 4]
In Japanese Patent No. 3934140 (International Publication WO2004 / 051155A1 Pamphlet), heat exchange is performed between the condenser, the evaporator, and the refrigerant from the evaporator to the compressor and the refrigerant in the process from the condenser to the evaporator. A single-stage refrigerator system constituted by a heat exchanger to be performed, and a non-azeotropic refrigerant used in the system, a refrigerant having a normal boiling point near normal temperature and a refrigerant having a low standard boiling point of -60 ° C or lower The dew point of the refrigerant at the pressure of the condensation process after compression is not less than the normal temperature, and the boiling point at that pressure is not less than the dew point at the low pressure of the process from the evaporator to the compressor. A non-azeotropic refrigerant for ultra-low temperature characterized by this is disclosed. As a combination of the refrigerant components, it is disclosed that butane, isobutane can be used as a refrigerant having a high boiling point near room temperature and low in vapor pressure, and ethane, ethylene, or the like can be used as a low boiling point refrigerant suitable for ultra-low temperatures.

[Patent Document 5]
JP-A 2007-169331 discloses another component (multi-component) non-azeotropic mixed solvent that can be used in a single-stage refrigeration system (one-component refrigerant refrigeration circuit), and has a temperature of -50 to -80 ° C. It is possible to achieve ultra-low temperatures with a non-azeotropic refrigerant that is only a mixture of two components that can achieve ultra-low temperatures, and from the viewpoint of protecting the global environment, the ozone depletion coefficient is zero, and global warming Non-azeotropic refrigerant mixtures having a very small coefficient (GWP) are disclosed.
Here, the single-stage refrigeration system (one-way refrigeration circuit) is a general conventional refrigeration circuit that has been used for a one-way refrigerant according to the prior art, such as specified CFCs, and includes a compressor and a condenser. A capillary tube, a liquid gas heat exchanger, and an evaporator.
By adopting another component (multi-component) non-azeotropic mixed solvent in which ethylene (C2H4) or ethane (C2H6) is added to isobutane (i-C4H10), a conventional multi-component refrigerant refrigeration circuit is not used. It is disclosed that it can be used for a general conventional single-stage refrigeration system (refrigeration circuit for one-way refrigerant) of the technology.
In the conventional single-stage refrigeration system (one-way refrigerant refrigeration circuit), in a preferred embodiment, an off-the-shelf freezer can be easily made into an ultra-low temperature freezer by using an entrainment type heat exchanger as a heat exchanger. Is disclosed to be possible.

JP-A-61-83258 JP-A-8-166172 Japanese Patent No. 3571296 Japanese Patent No. 3934140 JP 2007-169331 A

In view of the above problems in the prior art, problems to be solved by the invention set in the process of completing the present invention are listed below.

The first matter of the problem to be solved by the invention is to provide an ultra-low temperature ternary non-azeotropic refrigerant that can be used in an ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit).

The second problem to be solved by the invention is that it can be used smoothly and stably without remodeling the refrigerant circulation system of a conventional ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit). It is to provide an ultra-low temperature ternary non-azeotropic refrigerant.

The third problem to be solved by the invention is that the high-pressure system [evaporation for cooling the freezer (8) is performed in the refrigerant circulation system of a conventional ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit). The high-temperature refrigerant in the return path returning from the condenser (5) to the compressor (1)] in the low-pressure system [the forward path toward the evaporator (5) for cooling the freezer (8) from the condenser (2)] It is to provide an ultra-low temperature ternary non-azeotropic refrigerant that can be used smoothly and stably by adding a heat exchanger (3) having a function of cooling with a low-temperature refrigerant.

The fourth matter of the problem to be solved by the invention is to provide an ultra-low temperature ternary non-azeotropic refrigerant consisting of a gas having an ozone layer depletion coefficient (ODP) of only zero.

The fifth matter of the problem to be solved by the invention is to provide an ultra-low temperature ternary non-azeotropic refrigerant consisting only of a gas having a global warming potential (GWP) of 0 to 21.

Means for solving the problems will be described in detail below.

[First Invention] A non-azeotropic refrigerant for use in a single-stage refrigeration system,
The single-stage refrigeration system includes a compressor (1), a condenser (2), an evaporator, and a heat exchanger (3).
The heat exchanger (3) includes a high-temperature refrigerant in a high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)),
Having a function of exchanging heat with the low-temperature refrigerant in the low-pressure system [the forward path from the condenser (2) to the evaporator (5) for cooling the freezer (8)],
The non-azeotropic refrigerant is
At least one gas selected from the high boiling point gas (G1) group,
At least one gas selected from the low boiling point gas (G2) group,
as well as,
As at least three kinds of gas of at least one kind of gas selected from the group of extremely low boiling point gases (G3) as essential constituent requirements,
The boiling point Tb1 of the high boiling point gas (G1) group,
Boiling point Tb2 of the low boiling point gas (G2) group,
as well as,
The boiling point Tb3 of the extremely low boiling point gas (G3) group is
−273 ° C. ≦ Tb3 ≦ −130 ° C. <Tb2 <−20 ° C ≦ Tb1 ≦ + 60 ° C.
In the numerical range
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
60 parts by weight ≦ W1 ≦ 90 parts by weight,
10 parts by weight ≦ W2 ≦ 30 parts by weight,
0.1 parts by weight ≦ W3 ≦ 20 parts by weight, and
W1 + W2 + W3 = 100 parts by weight
further,
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
The dew point in the high pressure environment from the compressor (1) to the evaporator (5) for cooling the freezer (8) via the heat exchanger (3) is room temperature (immediately, a single-stage refrigeration system) The atmospheric temperature in the operating state) and the boiling point reaches the compressor (1) from the evaporator (5) for cooling the freezer (8) via the heat exchanger (3). A non-azeotropic refrigerant for ultra-low temperature, which is set to be higher than the dew point in a low-pressure environment up to.

[Second Invention] A non-fluorocarbon gas group in which at least one of the high boiling point gas (G1) group, the low boiling point gas (G2) group, and the extremely low boiling point gas (G3) group is excluded from the fluorocarbon gas group The non-azeotropic refrigerant for ultra-low temperatures described in the first aspect of the invention.

[Third Invention] The high boiling point gas (G1) contains butane (boiling point−0.5 ° C.), isobutane (boiling point−12 ° C.), butene (boiling point−6.9 ° C.), and ethylacetylene (boiling point + 8.1). At least one gas selected from the group consisting of:
The low boiling point gas (G2) is at least one gas selected from the group consisting of ethane (boiling point −88.68 ° C.), ethylene (boiling point −104.2 ° C.) and R-14 (boiling point −128 ° C.). And
The extremely low boiling point gas (G3) is methane (boiling point: −161.52 ° C.), the non-azeotropic refrigerant mixture for ultra-low temperature according to the first or second aspect of the invention.

[Fourth Invention] The weight composition ratio of three kinds of gases, a high boiling point gas (G1), a low boiling point gas (G2), and an extremely low boiling point gas (G3),
The high boiling point gas (G1) is 50 to 99.9 parts by weight,
Low boiling point gas (G2) is 5 to 50 parts by weight,
Extremely low boiling point gas (G3) is 0.01 to 10 parts by weight,
In addition, any one of the first to third inventions, wherein a total part by weight of the high boiling point gas (G1), the low boiling point gas (G2), and the extremely low boiling point gas (G3) is 100 parts by weight. Non-azeotropic refrigerant for ultra-low temperature described in 1.

[Fifth Invention] A total weight part W1 of a gas selected from the high boiling point gas (G1) group,
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
70 parts by weight ≦ W1 ≦ 80 parts by weight,
15 parts by weight ≦ W2 ≦ 25 parts by weight,
0.1 parts by weight ≦ W3 ≦ 10 parts by weight, and
The ultra-low temperature non-azeotropic refrigerant according to any one of the first to fourth inventions, which is in a numerical range of W1 + W2 + W3 = 100 parts by weight.

[Sixth Invention] A non-azeotropic refrigerant for use in a single-stage refrigeration system,
The single-stage refrigeration system includes a compressor (1), a condenser (2), an evaporator, and a heat exchanger (3).
The heat exchanger (3) includes a high-temperature refrigerant in a high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)),
Having a function of exchanging heat with the low-temperature refrigerant in the low-pressure system [the forward path from the condenser (2) to the evaporator (5) for cooling the freezer (8)],
The non-azeotropic refrigerant is
At least one gas selected from the high boiling point gas (G1) group,
At least one gas selected from the low boiling point gas (G2) group,
as well as,
As at least three kinds of gas of at least one kind of gas selected from the group of extremely low boiling point gases (G3) as essential constituent requirements,
The boiling point Tb1 of the high boiling point gas (G1) group,
Boiling point Tb2 of the low boiling point gas (G2) group,
as well as,
The boiling point Tb3 of the extremely low boiling point gas (G3) group is
−273 ° C. ≦ Tb3 ≦ −130 ° C. <Tb2 <−20 ° C ≦ Tb1 ≦ + 60 ° C.
In the numerical range
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
60 parts by weight ≦ W1 ≦ 90 parts by weight,
10 parts by weight ≦ W2 ≦ 30 parts by weight,
0.1 parts by weight ≦ W3 ≦ 20 parts by weight, and
W1 + W2 + W3 = 100 parts by weight
further,
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
The dew point in the high pressure environment from the compressor (1) to the evaporator (5) for cooling the freezer (8) via the heat exchanger (3) is room temperature (immediately, a single-stage refrigeration system) The atmospheric temperature in the operating state) and the boiling point reaches the compressor (1) from the evaporator (5) for cooling the freezer (8) via the heat exchanger (3). A non-azeotropic refrigerant for ultra-low temperature, which is set to be higher than the dew point in a low-pressure environment up to.

[Seventh Invention] A non-azeotropic refrigerant for use in a single-stage refrigeration system,
The single-stage refrigeration system includes a compressor (1), a condenser (2), an evaporator, and a heat exchanger (3).
The heat exchanger (3) includes a high-temperature refrigerant in a high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)),
Having a function of exchanging heat with the low-temperature refrigerant in the low-pressure system [the forward path from the condenser (2) to the evaporator (5) for cooling the freezer (8)],
The non-azeotropic refrigerant has three kinds of gas, high boiling point gas (G1), low boiling point gas (G2), and extremely low boiling point gas (G3) as essential constituent requirements.
The high boiling point gas (G1) is at least one gas selected from a gas group having a boiling point of −20 ° C. or higher and + 60 ° C. or lower,
The low boiling point gas (G2) is at least one gas selected from a gas group having a boiling point of more than −130 ° C. and less than −20,
The extremely low boiling point gas (G3) is at least one gas selected from a gas group having a boiling point of −273 ° C. or higher and −130 ° C. or lower,
The weight composition ratio of the three kinds of gases, the high boiling point gas (G1), the low boiling point gas (G2), and the extremely low boiling point gas (G3),
The dew point in the high pressure environment from the compressor (1) to the evaporator (5) for cooling the freezer (8) via the heat exchanger (3) is room temperature (immediately, a single-stage refrigeration system) The atmospheric temperature in the operating state) and the boiling point reaches the compressor (1) from the evaporator (5) for cooling the freezer (8) via the heat exchanger (3). A non-azeotropic refrigerant for ultra-low temperature, which is set to be higher than the dew point in a low-pressure environment up to.

[Eighth Invention] The boiling point Tb1 of the high boiling point gas (G1) group, the boiling point Tb2 of the low boiling point gas (G2) group, and the boiling point Tb3 of the extremely low boiling point gas (G3) group are:
−180 ° C. ≦ Tb3 ≦ −140 ° C.
−130 ° C. <Tb2 ≦ −80 ° C.,
−20 ° C. ≦ Tb1 ≦ + 10 ° C.
The ultra-low temperature non-azeotropic refrigerant according to any one of the first to seventh inventions, wherein the non-azeotropic refrigerant is in a numerical range.

The effects of the present invention are listed below.

The first matter of the effect of the invention is that it is possible to provide an ultra-low temperature ternary non-azeotropic refrigerant that can be used in an ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit).

The second effect of the invention is that it can be used smoothly and stably without modifying the refrigerant circulation system of a conventional ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit) 3 The original non-azeotropic refrigerant can be provided.

A third matter of the effect of the invention is that in a refrigerant circulation system of a conventional ultra-low temperature single-stage refrigeration system (one-way refrigeration circuit), a high-pressure system [an evaporator (5) for cooling a freezer (8) The high-temperature refrigerant in the return system returning from the compressor (1) to the compressor (1) is cooled by the low-temperature refrigerant in the low-pressure system [the outward system going from the condenser (2) to the evaporator (5) for cooling the freezer (8)]. It is possible to provide a ternary non-azeotropic refrigerant for ultra-low temperature that can be used smoothly and stably by adding a heat exchanger (3) having a cooling function.

The fourth matter of the effect of the invention is that it can provide a ternary non-azeotropic refrigerant for ultra-low temperature composed of a gas whose ozone depletion coefficient (ODP) is only zero.

The fifth matter of the effect of the invention is that it can provide a ternary non-azeotropic refrigerant for ultra-low temperature consisting of only a gas having a global warming potential (GWP) of 3 to 21.

In view of the problems in the prior art described above, the inventor of the present application searches for a hydrocarbon-based ultra-low temperature azeotropic refrigerant having no halogen (chlorine, fluorine, etc.) in the chemical structure. Ternary comprising a combination of 20 ° C. ≦ boiling point Tb1 ≦ + 60 ° C.), low boiling point gas (−130 ° C. <boiling point Tb2 <−20 ° C.), and extremely low boiling point gas (−273 ° C. ≦ boiling point Tb3 ≦ −130 ° C.) An experimental hypothesis that there may be special conditions for non-azeotropic refrigerants that can be condensed by a compression process near room temperature and can be condensed by cooling by heat exchange with the refrigerant in the evaporator, that is, We assumed an experimental hypothesis that there may be special conditions that can be used stably in a conventional single-stage refrigeration system (one-way refrigeration circuit).
If such a special condition exists, even if it is a non-azeotropic refrigerant under such special condition, a complicated mechanism such as gas-liquid separation is unnecessary, and the mechanism is simplified. The instability in the refrigerator operation due to the characteristic characteristic of the non-azeotropic refrigerant in which the boiling point and the dew point are inconsistent can be solved.
Therefore, since it would be extremely beneficial if such special conditions could be found, we intensively investigated the validity of this experimental hypothesis.

That is, the basic concept of the technical idea of the present invention is that there is no problem even if it is used in a conventional single-stage refrigeration system (one-way refrigeration circuit) that uses a specific chlorofluorocarbon, which is a refrigerant according to the prior art. It is based on the viewpoint of developing a hydrocarbon ultra-low temperature azeotropic refrigerant capable of exhibiting cooling performance equivalent to or higher than that of specific chlorofluorocarbon, which is a refrigerant based on technology.
From the viewpoint of reducing waste and protecting the environment, it is possible to continue to use conventional single-stage refrigeration systems (single-type refrigeration circuits) without discarding facilities that have used specific chlorofluorocarbons. Is also significant.

In the claims, specification and drawings of the present application, the term “ultra low temperature” in the term “single stage refrigeration system for ultra low temperature” means “−50 to −70 ° C.”, preferably “− “50 to −80 ° C.”, more preferably “−50 to −100 ° C.”, which means that it is possible to realize “ultra low temperature” as the freezer temperature.

In the claims, specification and drawings of the present application, the term “single-stage refrigeration system” is equivalent to the term “one-unit refrigerant refrigeration circuit” or “one-unit refrigeration circuit”. It means a system that circulates refrigerant with a single compressor.
A typical embodiment of a single stage refrigeration system (one-way refrigeration circuit) is shown in FIG.

A single-stage refrigeration system (one-way refrigeration circuit) circulates refrigerant using a single compressor, whereas a two-stage refrigeration system (two-way refrigeration circuit) is disclosed in Patent Document 5 (Japanese Patent Application Laid-Open Publication No. 2007-200759 As shown in FIG. 2 and paragraph numbers [0032] to [0036] of Japanese Patent No. 169331), different refrigerants are circulated in two compressors, and a low temperature is achieved by interposing a heat exchanger. A two-stage refrigeration circuit, that is, a first circuit (high temperature side refrigeration circuit) configured to include a high temperature side compressor and a second circuit (low temperature side) configured to include a low temperature side compressor This is a device that has two refrigeration circuits comprising a refrigeration circuit and obtains predetermined cold heat via a cascade heat exchanger.

FIG. 7 illustrates a two-stage refrigeration system (two-way refrigeration circuit).
In the first circuit (high temperature side refrigeration circuit), the first circuit refrigerant condensed in the high temperature side compressor (compressor) 1a and the condenser (condenser, air-cooled type or water-cooled type) 2 is evaporated in the cascade heat exchanger 3a ( And return to the high temperature side compressor (compressor) 1a.
The first circuit refrigerant (high-pressure circuit refrigerant, high-temperature circuit refrigerant) condenses at room temperature, and its evaporation temperature is about −30 ° C. to −40 ° C.

The second circuit (low temperature side refrigeration circuit) is a low temperature side capillary tube (condensation temperature of −15 to −20 ° C.) condensed by the low temperature side compressor (compressor) 1b and the cascade heat exchanger 3a. The second circuit refrigerant jetted and evaporated by the evaporator is cooled at the low temperature side compressor (compressor) by spraying and evaporating in the evaporator 5a via the decompressor 4a and cooling the inside of the freezers that are originally cooled. Return to the cascade heat exchanger 3a again via 1b.
The second circuit refrigerant (low-pressure circuit refrigerant, low-temperature circuit refrigerant) condenses at -15 to -20 ° C normal temperature, and the evaporation temperature is about -50 to -80 ° C.

In the cascade heat exchanger 3a, the cooled and condensed low-temperature first circuit refrigerant is fed from the first circuit side inlet, and after being injected and evaporated by the evaporator from the second circuit side inlet, the low-temperature side compressor (compressor) The high-temperature second circuit refrigerant compressed in step S3 is fed and heat exchange is performed between the two refrigerants to cool and condense the high-temperature second circuit refrigerant.

The second circuit is provided with an expansion tank 7 as a protective device, and when the gas pressure in the device becomes high when the circuit is stopped, the pressure in the device is increased by receiving excessive gas. Demonstrate the function to prevent.

The second circuit is provided with a low temperature side capillary tube (decompressor) 4b, and exhibits a function of depressurizing and evaporating the refrigerant gas condensed and liquefied by the condenser.

In the prior art, as the first circuit refrigerant (high-pressure circuit refrigerant), for example, R-22 (CHClF2, boiling point −40.8 ° C.), R-404a (R-143a / R-125 / R-134a). = 52/44/4 wt%, boiling point -46.6), etc., and as the second circuit refrigerant (low pressure side circuit refrigerant), for example, R-23 (CHF3, boiling point -82 ° C.) is used. I came.

In order to achieve a predetermined low temperature (−80 ° C.) in the evaporators (in the freezers), it is necessary to condense the refrigerant of R-23, not a single-stage refrigeration system (one-way refrigeration circuit). It was inevitable to adopt a two-stage refrigeration system (two-way refrigeration circuit).

A two-stage refrigeration system (two-way refrigeration circuit) requires almost twice as many parts as a single-stage refrigeration system (one-way refrigeration circuit), and the mechanism is complicated. It is difficult to apply to a small freezer.
The non-azeotropic refrigerant mixture according to the present invention is not a two-stage refrigeration system (binary refrigeration circuit) with a complicated mechanism and expensive manufacturing cost, but a single-stage refrigeration system with a simple mechanism and low manufacturing cost ( It can be used in a one-way refrigeration circuit).

In the claims, specification and drawings of the present application, the term “room temperature” means the ambient temperature in the operating state of the single-stage refrigeration system. For example, in Japan, It includes -10 to + 45 ° C, which is a general temperature range announced by the Japan Meteorological Agency with seasonal changes, but typically includes 30 ± 10 ° C.

In the claims, specification and drawings of the present application, the term “ternary non-azeotropic refrigerant mixture” means at least one kind of gas selected from the high boiling point gas (G1) group, a low boiling point gas ( It means a non-azeotropic refrigerant mixture comprising at least one kind of gas selected from the G2) group and at least one kind of gas selected from the extremely low boiling point gas (G3) group.

In the claims, specification and drawings of the present application, the boiling point Tb1 of the high boiling point gas (G1) group is:
−20 ° C. ≦ Tb1 ≦ + 60 ° C.
There is a numerical relationship.

In the claims, specification and drawings of the present application, the boiling point Tb2 of the low boiling point gas (G2) group is:
-130 ° C <Tb2 <-20 ° C
There is a numerical relationship.

In the claims, specification and drawings of the present application, the boiling point Tb3 of the extremely low boiling point gas (G3) group is:
−273 ° C. ≦ Tb3 ≦ −130 ° C.
There is a numerical relationship.

The single-stage refrigeration system includes a compressor (1), a condenser (2), an evaporator, and a heat exchanger (3).

The heat exchanger (3) includes a high-temperature refrigerant in a high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)) and a low-pressure system (condenser (2) To the evaporator (5) for cooling the freezer (8) to have a function of exchanging heat with the low-temperature refrigerant in the refrigerant.

The high-temperature refrigerant in the high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)) is cooled, and the low-pressure system [cools the freezer (8) from the condenser (2). For the gas-liquid separation, even if it is a non-azeotropic refrigerant, it can be condensed by the heat exchange in the heat exchanger (3) by the low-temperature refrigerant in the outbound system toward the evaporator (5) for It is possible to simplify the configuration of the entire system without adopting the complicated mechanism, and it is possible to continue to use the conventional single-stage refrigeration system (refrigeration circuit for one-way refrigerant) that uses specific chlorofluorocarbons. The refrigerator can be operated stably.

Therefore, the composition of the non-azeotropic refrigerant is changed from the high-temperature refrigerant in the high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)) with the low-pressure system [condenser ( 2) When the heat exchanger (3) performs heat exchange with the low-temperature refrigerant in the forward path toward the evaporator (5) for cooling the freezer (8), the high-pressure system [freezer (8) It is necessary to set so that the high-temperature refrigerant in the return path system from the evaporator (5) for cooling back to the compressor (1) can be condensed.
That is, although the composition of the non-azeotropic refrigerant is also described in Table-2 of Patent Document 4 (Patent No. 3934140) described above, for example, in Mode No. 1 and Mode No. 2 listed in Table-1 It is necessary to set so that such numerical values can be realized.

[Table-1] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside chamber High pressure system pressure Low pressure system pressure Low pressure system inlet Low pressure system outlet High pressure system inlet High pressure system outlet Temperature ° C (MPa) Temperature (° C) Temperature (° C) Temperature (° C) Temperature (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1 -75 0.9 0.02 -50 → +9 +29 → -39
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
2 -82 1.5 0.02 -38 → +12 +28 → −32
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

In Table 1, the measurement points are the low pressure system inlet (A), the low pressure system outlet (E), the high pressure system inlet (F), and the high pressure system outlet (B) as shown in FIG.
The temperature of the measurement item is the temperature in the pipe (° C.) and the gauge pressure in the pipe (MPa).

In Table 1, “No.” is a convenient serial number of the embodiment, and “internal temperature ° C.” is the internal temperature (° C.) of the freezer cooled by the evaporator (5). The “high pressure system pressure (MPa)” is the pressure (MPa) in the high pressure system [return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)]. The “low pressure system pressure (MPa)” is the pressure (MPa) in the low pressure system [the outward system from the condenser (2) to the evaporator (5) for cooling the freezer (8)]. The “inlet temperature (° C.)” is the temperature (° C.) at the inlet of the heat exchanger (3) of the low pressure system (the system that sends the refrigerant to the evaporator (5)). ) ”Is the temperature (° C.) at the outlet of the heat exchanger (3) of the low-pressure system (the system on the forward path that sends the refrigerant to the evaporator (5)), and the“ high-pressure system inlet temperature (° C.) ” Is the temperature (° C.) at the inlet of the heat exchanger (3) of the high pressure system (the system where the refrigerant returns from the evaporator (5)), and the “high pressure system outlet temperature (° C.)” This is the temperature (° C.) at the outlet of the heat exchanger (3) of the (return side system where the refrigerant returns from the evaporator (5)).

For the non-azeotropic refrigerant for ultra-low temperature according to the present invention, the dew point (° C.) and Tb (H) of the dew point (° C.) in the high-pressure system of non-azeotropic solvent (the system on the side where the refrigerant returns from the evaporator (5)) ), And the dew point (° C.) in the low-pressure system of the non-azeotropic solvent (the system on the side sending the refrigerant to the evaporator (5)) is Td (L) and the boiling point is Tb (L), the modes listed in Table 1 In No. 1 and Aspect No. 2, it is necessary to set the composition of the non-azeotropic refrigerant so that these numerical values satisfy the relationship shown in Table-2.

[Table-2] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside the chamber High pressure system pressure Low pressure system pressure Chamber temperature High pressure system refrigerant Low pressure system refrigerant High pressure system refrigerant Temperature ° C (MPa) (MPa) (° C) Dew point (° C) Dew point (° C) Boiling point (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1−75 0.9 0.02 + 30 ≦ Td (H) Td (L) <Tb (H)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
2−82 1.5 0.02 + 30 ≦ Td (H) Td (L) <Tb (H)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

That is, for the non-azeotropic refrigerant for ultra-low temperature according to the present invention, as shown in Table 2, an evaporator for cooling the freezer (8) from the compressor (1) via the heat exchanger (3) ( 5) An evaporator for cooling the freezer (8) so that the dew point in a high-pressure environment until reaching 5) is equal to or higher than room temperature (immediately, the ambient temperature in the single-stage refrigeration system operation state). It is necessary to set the composition of the non-azeotropic refrigerant so as to be higher than the dew point in a low pressure environment from (5) to the compressor (1) via the heat exchanger (3).

Regarding the characteristics of the non-azeotropic refrigerant necessary for understanding the technical background of the present invention, the system using the characteristics, and the preliminary knowledge about the experimental conditions, the third page of the Japanese Patent No. 3934140, page 13 Line 6 to page 44, page 6 line 48 to page 7 page 1, page 1, FIG. 20, Table 1, FIG. 1 and FIG.

Since the invention of the present application has been completed with the description in Japanese Patent No. 3934140 as one of the background arts, Japanese Patent No. 3934140 can be used for understanding the claims, specification and drawings of the present application. The contents described in the Japanese Patent Publication are matters that can be directly and uniquely derived from the claims, the specification, and the drawings of the present application.

The boiling point Tb1 of the high boiling point gas (G1) group, the boiling point Tb2 of the low boiling point gas (G2) group, and the boiling point Tb3 of the extremely low boiling point gas (G3) group are:
−273 ° C. ≦ Tb3 ≦ −130 ° C. <Tb2 <−20 ° C ≦ Tb1 ≦ + 60 ° C.
There is a numerical relationship.

The boiling point Tb1 of the high boiling point gas (G1) group, the boiling point Tb2 of the low boiling point gas (G2) group, and the boiling point Tb3 of the extremely low boiling point gas (G3) group are preferably
−180 ° C. ≦ Tb3 ≦ −140 ° C.
−130 ° C. <Tb2 ≦ −80 ° C.,
−20 ° C. ≦ Tb1 ≦ + 10 ° C.
There is a numerical relationship.

The boiling point Tb1 of the high boiling point gas (G1) group, the boiling point Tb2 of the low boiling point gas (G2) group, and the boiling point Tb3 of the extremely low boiling point gas (G3) group are more preferably,
−165 ° C. ≦ Tb3 ≦ −155 ° C.
−110 ° C. ≦ Tb2 ≦ −80 ° C.
−15 ° C. ≦ Tb1 ≦ + 10 ° C.
There is a numerical relationship.

The boiling point Tb1 of the high boiling point gas (G1) group, the boiling point Tb2 of the low boiling point gas (G2) group, and the boiling point Tb3 of the extremely low boiling point gas (G3) group are more preferably,
−165 ° C. ≦ Tb3 ≦ −155 ° C.
−110 ° C. ≦ Tb2 ≦ −80 ° C.
−15 ° C. ≦ Tb1 ≦ + 10 ° C.
There is a numerical relationship.

Preferred embodiments of the high boiling point gas (G1) are butane (boiling point -0.5 ° C), isobutane (boiling point -12 ° C), butene (boiling point -6.9 ° C), and ethylacetylene (boiling point + 8.1 ° C). At least one gas selected from the group consisting of:

A preferred embodiment of the low boiling point gas (G2) is at least one selected from the group consisting of ethane (boiling point−88.68 ° C.), ethylene (boiling point−104.2 ° C.) and R-14 (boiling point−128 ° C.). Gas.

A preferred embodiment of the extremely low boiling point gas (G3) is methane (boiling point−161.52 ° C.).
Extremely low boiling point gas (G3) is usually difficult to use alone in a single-stage refrigeration system, but by combining with high boiling point gas (G1) and low boiling point gas (G2) with low vapor pressure The high-temperature refrigerant in the high-pressure system [return system returning to the compressor (1) from the evaporator (5) for cooling the freezer (8)] is reduced by raising the liquefaction condensation temperature and lowering the vapor pressure. The low-temperature refrigerant in the forward path from the condenser (2) to the evaporator (5) for cooling the freezer (8)] is cooled by heat exchange in the heat exchanger (3) and condensed and liquefied. By this, it is possible to realize a smooth and stable operation of a refrigeration system [compression function force 15 to 20 atm (1.5 to 2.0 MPa)] that uses conventional specific chlorofluorocarbon widely used for many years as a refrigerant. .

The present invention comprising a gas selected from the high boiling point gas (G1) group, a gas selected from the low boiling point gas (G2) group, and a gas selected from the extremely low boiling point gas (G3) group. The preferred weight composition ratio of the non-azeotropic refrigerant is such that the total weight part of the gas selected from the high boiling point gas (G1) group is W1, the total weight part of the gas selected from the low boiling point gas (G2) group is W2, And when the total weight part of the gas selected from the extremely low boiling point gas (G3) group is W3,
70 parts by weight ≦ W1 ≦ 80 parts by weight,
15 parts by weight ≦ W2 ≦ 25 parts by weight,
0.1 parts by weight ≦ W3 ≦ 10 parts by weight, and
W1 + W2 + W3 = 100 parts by weight.

Isobutane (boiling point −12 ° C.) as high boiling point gas (G1), ethylene (boiling point −104.2 ° C.) as low boiling point gas (G2), and methane (boiling point −161.52 ° C.) as extremely low boiling point gas (G3) ) Is selected, the preferred composition weight ratio is W1 for the high boiling point gas (G1), W2 for the low boiling point gas (G2), and W3 for the very low boiling point gas (G3). Then
72 to 80 parts by weight of W1,
19 to 21 parts by weight of W2,
1 to 7 parts by weight of W3,
The total of W1, W2 and W3 is 100 parts by weight.

Table 3 shows specific examples of high boiling point gas (G1) group (−20 ° C. ≦ Tb1 ≦ + 60 ° C.), and Table 4 shows specific examples of low boiling point gas (G2) group (−130 ° C. ≦ Tb2 <−20 ° C.). Table 6 shows specific examples of the extremely low boiling point gas (G3) group (−273 ° C. ≦ Tb3 <−60 ° C.).
The boiling point is a boiling point at standard atmospheric pressure (1 [atm]).

[Table-3] Specific examples of high boiling point gas (G1) group (-20 ° C ≦ Tb1 ≦ + 60 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Compound name Chemical formula Boiling point (° C) Critical temperature (° C) Vapor pressure (MPa)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Silicon tetrachloride SiCl4 57.6
Sulfur disulfide CS2 46.3
Phosphorus trichloride SiHCl3 31.8
Hydrogen cyanide HCN 25.7
Nitrogen dioxide NO2 21.3
Hydrogen fluoride HF 19.51
Tungsten hexafluoride WF6 17.1
Vinyl bromide C2H3Br 15.7
Boron trichloride BCl3 12.4
Ethyl chloride C2H5Cl 12.3
Ethylene oxide C2H4O 10.7
Dimethylpropane C5H12 9.5
Dichlorosilane SiH2Cl2 8.4
Ethylacetylene C4H6 8.1 191 0.05 (21 ° C.)
Phosgene COCl2 7.55
Methyl mercaptan CH4SH 5.96
Cis-2-butene C4H8 3.73 155 0.1 (21 ° C.)
Methyl bromide CH3Br 3.56
Trimethylamine N (CH3) 3 2.87
Trans-2-butene C4H8 0.88 155 0.1 (21 ° C.)
Normal butane C4H10 −0.5 153.2 0.11 (21 ° C.)
1,3 Butadiene C4H6-4.5
1-butene C4H8-6.3 146 0.17 (21 ° C.)
Isobutene C4H8-6.9 145.0 0.17 (21 ° C.)
Sulfurous acid gas SO2-10
Isobutane C4H10-11.7 135.0 0.22 (21 ° C.)
Vinyl chloride C2H3Cl-13.8
Silicon tetrafluoride SiF4 -14.2
Disilane Si2H6-14.3
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

[Table-4] Specific examples of low boiling point gas (G2) group (-130 ° C <Tb2 <-20 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Compound name Chemical formula Boiling point (° C) Critical temperature (° C) Vapor pressure (MPa)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Methylacetylene C3H4-23.21
Methyl chloride CH3Cl-24.2
Dimethyl ether C2H6O-24.82
R-134a CH2FCF3-26.1 101.2 0.58 (21 ° C.)
Cyclopropane C3H6-32.8
Ammonia NH3-33.4
Chlorine Cl2-34.1
Allen C3H4-34.4
Sulfur tetrafluoride SF4 -40.4
Hydrogen selenide H2Se -41.4
Propane C3H8 -42.1
Propylene C3H6 -47.72
Carbonyl sulfide COS-50.23
Arsenic pentafluoride AsF5 -52.8
Arsine AsH3-55.2
Sulfuryl fluoride SO2F2-55.4
Hydrogen sulfide H2S-60.3
Sulfur hexafluoride SF6-63.8
Hydrogen bromide HBr -66.72
Vinyl fluoride C2H3F-72.2
Carbon dioxide CO2-75.8
Methyl fluoride CH3F -78.41
R-23 CHF3-80
Phosphorus pentafluoride PH5 -84.5
Hydrogen chloride HCl -85
Phosphine PH3-87.77
Nitrous oxide N2O-88.5
GERMANY Ge-88.5
Ethane C2H6-88.68 32.2 3.8 (21 ° C)
Diborane B2H6-92
Boron trifluoride BF3-100.3
Phosphorus trifluoride PF3-101.5
Ethylene C2H4-104.2
Xenon Xe-108.1
Silane SiH4-111.4
Nitrogen trifluoride NF3-129
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

[Table-5] Specific examples of extremely low boiling point gas (G3) group (−273 ° C. ≦ Tb3 ≦ −130 ° C.)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Compound name Chemical formula Boiling point (° C) Critical temperature (° C) Vapor pressure (MPa)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Nitric oxide NO-151.7
Krypton Kr-153.35
Methane CH4-161.52
Oxygen O2 -183
Argon Ar-186
Fluorine F2-188.2
Carbon monoxide CO-192
Nitrogen N2 -195.803
Neon Ne -246.05
Hydrogen H2 -252.766
Helium He -268.9
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

[Example 1]
<Types of gas constituting non-azeotropic refrigerant>
As the types of gases constituting the non-azeotropic refrigerant, isobutane (boiling point Tb1 = −11.7 ° C.) from the high boiling point gas (G1) group, and ethylene (boiling point Tb2 == from the low boiling point gas (G2) group. -104.2 ° C.) was selected from the extremely low boiling point gas (G3) group, methane (boiling point Tb3 = −161.52 ° C.).

<Weight composition ratio of gas constituting non-azeotropic refrigerant>
The weight composition ratio of the gas constituting the non-azeotropic refrigerant is based on the total weight of isobutane (high boiling point gas, G1), ethylene (low boiling point gas, G2), and methane (very low boiling point gas, G3) (100 Parts by weight) were 72 parts by weight of isobutane, 21 parts by weight of ethylene, and 7 parts by weight of methane.

<Refrigeration equipment>
As the refrigeration apparatus, the single-stage refrigeration system (single unit refrigeration circuit) shown in FIG. 1 was used, and 250 g of non-azeotropic refrigerant was charged for operation.
The operation was started, and measurement was performed with the heat exchanger (3) in a steady state.

[Table-6] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside chamber High pressure system pressure Low pressure system pressure Low pressure system inlet Low pressure system outlet High pressure system inlet High pressure system outlet Temperature ° C (MPa) Temperature (° C) Temperature (° C) Temperature (° C) Temperature (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1 −90 1.7 0.09 −45 → +2 +30 → −40
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

In Table-6, the measurement points are the low pressure system inlet (A), the low pressure system outlet (E), the high pressure system inlet (F), and the high pressure system outlet (B) as shown in FIG. Are the pipe internal temperature (° C.) and the pipe internal gauge pressure (MPa).
In Table-6, “No.” is an example number, and “internal temperature ° C.” is the internal temperature (° C.) of the freezer cooled by the evaporator (5).

[Example 2]
<Types of gas constituting non-azeotropic refrigerant>
As the types of gases constituting the non-azeotropic refrigerant, isobutane (boiling point Tb1 = −11.7 ° C.) from the high boiling point gas (G1) group, and ethylene (boiling point Tb2 == from the low boiling point gas (G2) group. -104.2 ° C.) was selected from the extremely low boiling point gas (G3) group, methane (boiling point Tb3 = −161.52 ° C.).

<Weight composition ratio of gas constituting non-azeotropic refrigerant>
The weight composition ratio of the gas constituting the non-azeotropic refrigerant is based on the total weight of isobutane (high boiling point gas, G1), ethylene (low boiling point gas, G2), and methane (very low boiling point gas, G3) (100 Parts by weight) was 80 parts by weight of isobutane, 19 parts by weight of ethylene, and 1 part by weight of methane.

<Refrigeration equipment>
As the refrigeration apparatus, the single-stage refrigeration system (single unit refrigeration circuit) shown in FIG. 1 was used, and 250 g of non-azeotropic refrigerant was charged for operation.
The operation was started, and measurement was performed with the heat exchanger (3) in a steady state.

[Table-7] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside chamber High pressure system pressure Low pressure system pressure Low pressure system inlet Low pressure system outlet High pressure system inlet High pressure system outlet Temperature ° C (MPa) Temperature (° C) Temperature (° C) Temperature (° C) Temperature (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
2 −82 1.2 0.05 −40 → +10 +30 → −31
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

In Table 7, the measurement points are the low pressure system inlet (A), the low pressure system outlet (E), the high pressure system inlet (F), and the high pressure system outlet (B) as shown in FIG. Are the pipe internal temperature (° C.) and the pipe internal gauge pressure (MPa).
In Table-6, “No.” is an example number, and “internal temperature ° C.” is the internal temperature (° C.) of the freezer cooled by the evaporator (5).

[Comparative Example 1]
<Types of gas constituting non-azeotropic refrigerant>
As the types of gases constituting the non-azeotropic refrigerant, isobutane (boiling point Tb1 = −11.7 ° C.) from the high boiling point gas (G1) group, and ethylene (boiling point Tb2 == from the low boiling point gas (G2) group. -104.2 ° C.) was selected from the extremely low boiling point gas (G3) group, methane (boiling point Tb3 = −161.52 ° C.).

<Weight composition ratio of gas constituting non-azeotropic refrigerant>
A butane-ethylene mixed non-azeotropic refrigerant in which the weight composition ratio of the gas constituting the non-azeotropic refrigerant was 85% by weight of butane / 15% by weight of ethylene was prepared.

<Refrigeration equipment>
As the refrigeration apparatus, the single-stage refrigeration system (single unit refrigeration circuit) shown in FIG. 1 was used, and 250 g of non-azeotropic refrigerant was charged for operation.
The operation was started, and measurement was performed with the heat exchanger (3) in a steady state.

[Table-8] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside chamber High pressure system pressure Low pressure system pressure Low pressure system inlet Low pressure system outlet High pressure system inlet High pressure system outlet Temperature ° C (MPa) Temperature (° C) Temperature (° C) Temperature (° C) Temperature (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1 -75 0.9 0.02 -50 → +9 +29 → -39
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

In Table-8, the measurement points are the low pressure system inlet (A), the low pressure system outlet (E), the high pressure system inlet (F), and the high pressure system outlet (B) as shown in FIG. Are the pipe internal temperature (° C.) and the pipe internal gauge pressure (MPa).
In Table-8, “No.” is a comparative example number, and “internal temperature ° C.” is the internal temperature (° C.) of the freezer cooled by the evaporator (5).

[Comparative Example 2]
<Types of gas constituting non-azeotropic refrigerant>
As the types of gases constituting the non-azeotropic refrigerant, isobutane (boiling point Tb1 = −11.7 ° C.) from the high boiling point gas (G1) group, and ethylene (boiling point Tb2 == from the low boiling point gas (G2) group. -104.2 ° C.) was selected from the extremely low boiling point gas (G3) group, methane (boiling point Tb3 = −161.52 ° C.).

<Weight composition ratio of gas constituting non-azeotropic refrigerant>
Butane-ethylene-R14 in which the weight composition ratio of the gas constituting the non-azeotropic refrigerant was 260 parts by weight in total of butane 212.5 parts by weight, ethylene 37.5 parts by weight, R-14 (fluoromethane) 10 parts by weight. A (fluoromethane) mixed non-azeotropic refrigerant was prepared.
The weight composition ratio of the non-azeotropic refrigerant is 81.7% by weight for butane, 14.4% by weight for ethylene, and 3.8% by weight for R-14 (fluoromethane).

<Refrigeration equipment>
The single-stage refrigeration system (one-way refrigeration circuit) shown in FIG. 1 was used as the refrigeration apparatus, and 260 g of non-azeotropic refrigerant was charged for operation.
The operation was started, and measurement was performed with the heat exchanger (3) in a steady state.

[Table-9] Heat exchanger inlet and outlet temperatures (room temperature 30 ° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
No. Inside chamber High pressure system pressure Low pressure system pressure Low pressure system inlet Low pressure system outlet High pressure system inlet High pressure system outlet Temperature ° C (MPa) Temperature (° C) Temperature (° C) Temperature (° C) Temperature (° C)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
2 -82 1.5 0.02 -38 → +12 +28 → −32
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

In Table-9, the measurement points are the low pressure system inlet (A), the low pressure system outlet (E), the high pressure system inlet (F), and the high pressure system outlet (B) as shown in FIG. Are the pipe internal temperature (° C.) and the pipe internal gauge pressure (MPa).
In Table-9, “No.” is a comparative example number, and “internal temperature ° C.” is the internal temperature (° C.) of the freezer cooled by the evaporator (5).

Comparing Examples 1 and 2 using methane (boiling point -162 ° C) with Comparative Example 2 using R-14 (perfluoromethane, boiling point -128 ° C), Examples 1 and 2 using methane In the case of, the cooling temperature was lower.
Furthermore, the global warming potential (GWP) of R-14 used in Comparative Example 2 was 6500, whereas the global warming potential (GWP) of methane used in Examples 1 and 2 was 21, which was extremely small. It was.

Next, referring to FIGS. 3 to 6, a typical cryogenic refrigeration system (one-way refrigeration circuit) that uses the cryogenic non-azeotropic refrigerant mixture according to the present invention, and a heat exchanger (entrainment) used in the system. Mold heat exchanger, etc.) will be described.

In FIG. 4 (A), the basic configuration of the entrainment type heat exchanger 3b has three recesses 31a, 31a, 31a extending along the axial direction on the peripheral wall of one first heat exchange pipe 31. Three second heat exchange pipes 32, 32, 32 are crimped and fixed in a heat exchange relationship with the first heat exchange pipe 31 inside the three recesses 31 a, 31 a, 31 a.
Further, the three second heat exchange pipes 32, 32, 32 are connected at both ends by branching / combining tubes (not shown). In other words, the three second heat exchange pipes 32, 32, 32 are bundled at both ends and connected by a branching / merging pipe to form one pipe.

The basic configuration of the entrainment type heat exchanger shown in FIGS. 4 (A) and 4 (B) is, as shown in FIGS. 5 and 6, due to the refrigeration capacity of the refrigeration apparatus, the size of the apparatus, etc. Used in the form of a track or the like.

FIG. 5 shows a U-shaped wrap-around heat exchanger 3c in which the basic configuration of the wrap-around heat exchanger is formed in a U-shape.
FIG. 6 shows a track-type heat exchanger 3d in which the heat exchanger is formed into a track shape. As shown in the plan view of FIG. 6 (a), both ends are semicircular and the central portion is linear. As shown in the front view of FIG. 6B, they are used in an overlapping manner.

In FIG. 6 (b), they are used in a three-layered manner. The shape is not limited to the U shape or the track shape, and a free shape such as a straight shape, a circular shape, an elliptical shape or the like can be selected.
In FIGS. 5 and 6, only two of the second heat exchange pipes 32 are shown in order to avoid complexity of the drawings, but actually, as shown in FIGS. 4 (A) and 4 (B). Three second heat exchange pipes 32, 32, 32 are crimped and fixed to the first heat exchange pipe 31.

As shown in FIG. 4A, for example, the left end of the first heat exchange pipe 31 communicates with the low-pressure side heat exchange outlet 16, and the left ends of the second heat exchange pipes 32, 32, and 32 are connected to the branching / combining tubes. They are bundled and communicated with the high-pressure side heat exchanger inlet 18. The right end of the first heat exchange pipe 31 communicates with the low-pressure side accumulator outlet 15, and the right ends of the second heat exchange pipes 32, 32, and 32 are bundled with a branching / combining tube, and the high-pressure side subcooling heat exchange is performed. It communicates with the vessel outlet 13.

[Industrial utility]
The ultra-low temperature non-azeotropic refrigerant according to the present invention can be stably operated over a long period of time even when used in a refrigeration system having a simple configuration, that is, a single-stage refrigeration system.
Since the single-stage refrigeration system has a simple configuration, the manufacturing cost and the maintenance / maintenance / maintenance / repair costs are relatively low.

The ultra-low temperature non-azeotropic refrigerant according to the present invention can easily achieve an ultra-low temperature of −60 ° C. or less with an inexpensive gas component, and in particular, can stably maintain an ultra-low temperature of −80 ° C. or less. Can be widely used for long-term preservation of biological tissues, especially valuable biological tissues used for transplantation and tissue culture, in response to the demands of these bio industries. It contributes.

The non-azeotropic refrigerant for ultra-low temperature according to the present invention can effectively improve the refrigerating capacity without using fluorocarbon as a refrigerant in combination with a hydrocarbon refrigerant, so that the amount of CFCs used is completely zero. The environmental impact such as the greenhouse effect is extremely small.

FIG. 1 is a conceptual diagram of an embodiment using a non-azeotropic refrigerant mixture for ultra-low temperature according to the present invention and a refrigeration system (one-way refrigeration circuit) used in the examples. FIG. 2 shows a typical ultra-low temperature refrigeration system (one-way refrigeration circuit) using the ultra-low temperature non-azeotropic refrigerant mixture according to the present invention. FIG. 3 is a conceptual diagram of the heat exchanger of the refrigeration system used in the embodiment of the present invention. (A) is a bird's-eye view, and (B) is a cross-sectional view of (A). FIG. 4 is a typical embodiment of a wrap-around heat exchanger. (A) is a bird's-eye view, (B) is an AA site | part sectional view of (A). FIG. 5 shows a U-shaped entrainment heat exchanger. FIG. 6 is a track-type entrainment heat exchanger, (A) is a plan view, and (B) is a front view. FIG. 7 is a typical embodiment of a binary refrigeration circuit.

Explanation of symbols

1 Compressor 1a High pressure side compressor (high temperature side compressor)
1b Low pressure side compressor (low temperature side compressor)
2 Condenser
2a Wire condenser 2b Skin condenser 3 Heat exchanger 3a Cascade heat exchanger 3b Entrainment type heat exchanger 3c U type entrainment type heat exchanger 3d Track type entrainment type heat exchanger 4 Throttle valve (capillary tube, decompressor)
4a High temperature side (high pressure side) capillary tube (decompressor)
4b Low temperature side (low pressure side) capillary tube (decompressor)
5 Evaporator (Evaporator)
6 Accumulator (Liquid inhaler)
7 Expansion Tank 8 Freezer 9 Accumulator 11 Compressed Gas Outward Pipe 12 Compressed Gas Return Pipe X Joint (joined by brazing, welding, etc.)
G1 Heat exchanger / high pressure system (high pressure side, high temperature side, forward path system) inlet G2 Heat exchanger / high pressure system (high pressure side, high temperature side, forward path system) outlet B1 Heat exchanger / low pressure system (low pressure side, low temperature side, Return system) Inlet B2 Heat exchanger, low pressure system (low pressure side, low temperature side, return system) outlet

13 High pressure side subcooling heat exchanger outlet temperature measurement point 14 Low pressure side evaporator outlet Temperature measurement point 15 Low pressure side accumulator outlet Temperature measurement point 16 Low pressure side heat exchanger outlet temperature measurement point 17 Low pressure side evaporator inlet temperature measurement point 18 High pressure side Heat exchanger entrance temperature measurement point 31 first heat exchange pipe 31a hollow portion 32 second heat exchange pipe

Claims (5)

A non-azeotropic refrigerant for use in a single stage refrigeration system,
The single-stage refrigeration system includes a compressor (1), a condenser (2), an evaporator, and a heat exchanger (3).
The heat exchanger (3) includes a high-temperature refrigerant in a high-pressure system (return system returning from the evaporator (5) for cooling the freezer (8) to the compressor (1)),
Having a function of exchanging heat with the low-temperature refrigerant in the low-pressure system [the forward path from the condenser (2) to the evaporator (5) for cooling the freezer (8)],
The non-azeotropic refrigerant is
At least one gas selected from the high boiling point gas (G1) group,
At least one gas selected from the low boiling point gas (G2) group,
as well as,
As at least three kinds of gas of at least one kind of gas selected from the group of extremely low boiling point gases (G3) as essential constituent requirements,
The boiling point Tb1 of the high boiling point gas (G1) group,
Boiling point Tb2 of the low boiling point gas (G2) group,
as well as,
The boiling point Tb3 of the extremely low boiling point gas (G3) group is
−273 ° C. ≦ Tb3 ≦ −130 ° C. <Tb2 <−20 ° C ≦ Tb1 ≦ + 60 ° C.
In the numerical range
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
60 parts by weight ≦ W1 ≦ 90 parts by weight,
10 parts by weight ≦ W2 ≦ 30 parts by weight,
0.1 parts by weight ≦ W3 ≦ 20 parts by weight, and
W1 + W2 + W3 = 100 parts by weight
further,
A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
The dew point in the high pressure environment from the compressor (1) to the evaporator (5) for cooling the freezer (8) via the heat exchanger (3) is room temperature (immediately, a single-stage refrigeration system) The atmospheric temperature in the operating state) and the boiling point reaches the compressor (1) from the evaporator (5) for cooling the freezer (8) via the heat exchanger (3). A non-azeotropic refrigerant for ultra-low temperature, which is set to be higher than the dew point in a low-pressure environment up to. At least one of the high boiling point gas (G1) group, the low boiling point gas (G2) group, and the extremely low boiling point gas (G3) group is a non-fluorocarbon gas group excluding the fluorocarbon gas group The non-azeotropic refrigerant for ultra-low temperature according to claim 1. High boiling point gas (G1) is a group consisting of butane (boiling point -0.5 ° C), isobutane (boiling point-12 ° C), butene (boiling point -6.9 ° C), and ethylacetylene (boiling point + 8.1 ° C). At least one gas selected from
The low boiling point gas (G2) is at least one gas selected from the group consisting of ethane (boiling point −88.68 ° C.), ethylene (boiling point −104.2 ° C.) and R-14 (boiling point −128 ° C.). And
The ultra-low temperature non-azeotropic refrigerant mixture according to claim 1 or 2, wherein the extremely low boiling point gas (G3) is methane (boiling point -161.52 ° C). The weight composition ratio of the three kinds of gases, the high boiling point gas (G1), the low boiling point gas (G2), and the extremely low boiling point gas (G3),
The high boiling point gas (G1) is 50 to 99.9 parts by weight,
Low boiling point gas (G2) is 5 to 50 parts by weight,
Extremely low boiling point gas (G3) is 0.01 to 10 parts by weight,
The total weight part of the high boiling point gas (G1), the low boiling point gas (G2), and the extremely low boiling point gas (G3) is 100 parts by weight. Non-azeotropic refrigerant for ultra-low temperature. A total weight part W1 of a gas selected from the high boiling point gas (G1) group;
A total weight part W2 of a gas selected from the low boiling point gas (G2) group,
as well as,
Total weight part W3 of the gas selected from the extremely low boiling point gas (G3) group
The weight composition ratio of
70 parts by weight ≦ W1 ≦ 80 parts by weight,
15 parts by weight ≦ W2 ≦ 25 parts by weight,
0.1 parts by weight ≦ W3 ≦ 10 parts by weight, and
The non-azeotropic refrigerant for ultra-low temperature according to any one of claims 1 to 4, wherein W1 + W2 + W3 = 100 parts by weight.