JP2532736B2 - Working fluid - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a working fluid used for a heat pump device such as an air conditioner and a refrigerator.

2. Description of the Related Art Conventionally, in heat pump devices such as air conditioners and refrigerators, fluorocarbons (hereinafter referred to as ROO or ROO) are used as a working fluid.
Halogenated hydrocarbons referred to as ○) are known, and are usually used when the condensing temperature and / or the evaporating temperature are in the range of about 0 to about 50 ° C. Among them, chlorodifluoromethane (CHClF ₂ , R22) is widely used as a working fluid for home air conditioners, building air conditioners, large refrigerators and the like.

Problems to be Solved by the Invention However, in recent years, stratospheric ozone depletion due to chlorofluorocarbons has become a global environmental problem. Use and production are regulated by the Convention, and there is a movement to abolish the use and production of specified CFCs in the future. Now, R22 has a very small ozone depletion potential (stratospheric ozone depletion potential when the stratospheric ozone destruction capability of trichlorofluoromethane (CCl ₃ F) is set to 1, hereinafter referred to as ODP) of 0.05, which is not a specific CFC. At present, refrigeration / air-conditioning equipment is widely spread, and it is expected that an increase in the usage and production of R22 will have a greater impact on human life environment. Therefore, although the stratospheric ozone destruction ability is small, there is a strong demand for early development of a working fluid that can substitute for R22, which is considered to have some destruction ability.

The present invention has been made in view of the above-described problems, and provides a working fluid that has almost no influence on the stratospheric ozone layer and is an alternative to R22.

Means for Solving the Problems The present invention provides at least trifluoroethane (C ₂ H
₃ F ₃ ), tetrafluoroethane (C ₂ H ₂ F ₄ ) and difluoroethane (C ₂ H ₄ F ₂ ), including three types of CFCs, trifluoroethane approximately 55 to approximately 80% by weight, tetrafluoroethane 0 to
The composition range is about 45% by weight and 0 to about 35% by weight of difluoroethane, and particularly about 55 to about 80% by weight of trifluoroethane and 0 of tetrafluoroethane.
It is desirable that the composition range is from about 45% by weight to about 0% to about 30% by weight of difluoroethane.

Effect The present invention uses the above-mentioned combination to change the working fluid into trifluoroethane (ODP = 0) and tetrafluoroethane (ODP = 0), which are fluorocarbons having almost no ozone depletion ability and containing no chlorine in the molecular structure. The use of a mixture of and difluoroethane (ODP = 0) makes it possible to make the influence on the stratospheric ozone layer even smaller than that of R22 and to almost eliminate it. In addition, the present invention has a vapor pressure similar to that of R22 at about 0 to about 50 ° C., which is the use temperature of a heat pump device such as an air conditioner or a refrigerator, by setting the above composition range, and the present invention is used as a substitute for R22. It is possible to provide a working fluid usable in the device. Therefore, the ODP in the combination and composition range described above is also expected to be 0, which is a very promising working fluid as a substitute for R22. In addition, since such a mixture becomes a non-azeotropic mixture and has a temperature gradient in the condensation process and the evaporation process, a coefficient of performance higher than that of R22 can be expected by configuring a Lorentz cycle with a temperature difference close to that of the heat source fluid. It is.

In general, fluorocarbons capable of depleting stratospheric ozone tend to have a greater effect of global warming as the ODP value increases, but the working fluid according to the present invention has an ODP of 0.
It is estimated that the effect of global warming is the same as R22 or less than R22 because it is composed of a mixture of three or more fluorocarbons. It is also possible to make it small.

Embodiment An embodiment of a working fluid according to the present invention will be described below with reference to the drawings.

Figure 1 shows 1,1,1-trifluoroethane (R143a), 1,
The equilibrium state of a working fluid composed of a mixture of three freons of 1,1,2-tetrafluoroethane (R134a) and 1,1-difluoroethane (R152a) at a constant temperature and a constant pressure is calculated using triangular coordinates. It is shown. In the triangular coordinates, a single substance is arranged at each vertex of the triangle in the order of lower boiling point in a counterclockwise direction from the upper vertex as a base point, and the composition ratio (weight ratio) of each component at a certain point on the coordinate plane Is represented by the ratio of the distance between the point and each side of the triangle. At this time, the distance between the point and the side of the triangle corresponds to the composition ratio of the substance described at the vertex of the triangular coordinates on the side opposite to the side. In Fig. 1, 1 is temperature 0 ° C, pressure 4.044kg / cm
^It is the vapor-liquid equilibrium line of the mixture at ² G, and this temperature and pressure correspond to the saturated state of R22. The upper line of the vapor-liquid equilibrium line (R22 0 ° C equivalent) 1 is the saturated vapor phase line, and the vapor-liquid equilibrium line (R220 ° C).
The lower line (corresponding to ° C.) 1 represents a saturated liquidus line, and a gas-liquid equilibrium state is established in the range sandwiched between these two lines. Also 2
Is the vapor-liquid equilibrium line of the mixture at a temperature of 50 ° C and a pressure of 18.782 kg / cm ² G, and this temperature and pressure also correspond to the saturated state of R22. As you can see, R143a, R134a and R152a
Are approximately 55 to approximately 80% by weight, 0 to approximately 45% by weight, 0 to approximately
A composition range of 35% by weight is desirable because it has a vapor pressure almost equal to that of R22 at a use temperature of about 0 to about 50 ° C. Further, R143a, R134a and R152a are each approximately 55
~ 80 wt%, 0 ~ 45 wt%, 0 ~ 30 wt% of the composition range has a vapor pressure almost equal to R22 at all use temperatures between 0 ℃ and 50 ℃ Especially desirable.

The composition of the working fluid at points A ₁ to F ₁ in FIG.
Shown in the table. Points A ₁ ~ point C ₁ is a gas-liquid equilibrium line (R22 50 ° C. equivalent)
On the saturated gas phase line 2, points D ₁ to F ₁ correspond to the vapor-liquid equilibrium line (R22 5
(Equivalent to 0 ° C) is on the saturated liquidus line of 2 and both are gas-liquid equilibrium lines (R
22 Equivalent to 0 ° C) 1 saturated vapor line and vapor-liquid equilibrium line (R22
Since it is in the range between the two saturated liquidus lines at 0 ° C, the gas-liquid equilibrium state is established at a temperature of 0 ° C and a pressure of 4.044 kg / cm ² G (corresponding to the saturated state of R22). . Therefore, the working fluid having the composition shown in Table 1 is saturated at 0 ° C and 50 ° C under the saturated vapor pressure of R22. By achieving a liquid-vapor equilibrium state and operating at a saturated vapor pressure of R22 at the temperature of use of approximately 0 to approximately 50 ° C, it is possible to obtain a condensation temperature / evaporation temperature almost equal to that of R22. It will be.

Although only the points on the gas-liquid equilibrium line (R22 50 ° C equivalent) 2 are described here, points inside the points A ₁ to F ₁ , that is, temperature 0 ° C, pressure 4.044 kg / cm ² G and By operating in the same manner, a working fluid having a composition that is in a vapor-liquid equilibrium state at a temperature of 50 ° C and a pressure of 18.782 kg / cm ² G (both of which are equivalent to the saturated state of R22) can be used at a temperature of approximately 0 to approximately 50 ° C. It is possible to obtain the condensation temperature and the evaporation temperature which are almost equal to those of R22.

Fig. 2 shows the equilibrium state of a working fluid composed of a mixture of three fluorocarbons, R143a, 1,1,2,2-tetrafluoroethane (R134) and R152a, at constant temperature and constant pressure in triangular coordinates. It is shown by using. In this triangular coordinate, the standard boiling point at atmospheric pressure is R13 for R152a.
Although lower than 4, in relation to Fig. 1, at each vertex of the triangle, counterclockwise from the upper vertex, R143
A single substance is arranged in the order of a, R134, and R152a. In Fig. 2, 3 is the vapor-liquid equilibrium line of the mixture at a temperature of 0 ° C and a pressure of 4.044 kg / cm ² G, and 4 is a temperature of 50 ° C and a pressure of 1.
8 is a vapor-liquid equilibrium line of the mixture at 8.782 kg / cm ² G. In this case, R143a, R134 and R152a are each approximately 65 to approximately 80.
%, 0 to about 35% by weight, 0 to about 35% by weight is desirable because the composition range has almost the same vapor pressure as R22, and R143a, R134 and R152a are each about 70 to about 80% by weight. A composition range of 0 to about 30% by weight, 0 to about 30% by weight is particularly desirable.

The composition of the working fluid at points A ₂ to F ₂ in FIG.
Shown in the table. Points A ₂ to C ₂ are gas-liquid equilibrium lines (equivalent to R22 50 ° C)
On the saturated vapor line of point 4, point D ₂ to point F ₂ are on the saturated liquidus line of the gas-liquid equilibrium line (R22 50 ° C equivalent) 4, and both of them are the saturated vapor phase line and the gas-liquid equilibrium line (R22 0 ° C) of 3 Since it is in the range sandwiched by both saturated liquidus lines of 3), the temperature is 0 ° C.
At a pressure of 4.044 kg / cm ² G (corresponding to the saturated state of R22), a gas-liquid equilibrium state is established. Therefore, the working fluid having the composition shown in Table 2 achieves a saturated state or a gas-liquid equilibrium state under the condition of the saturated vapor pressure of R22 at 0 ° C. and 50 ° C.
At an operating temperature of approximately 0 to approximately 50 ° C, R22 at the same temperature
By operating at a saturated vapor pressure of, it is possible to obtain a condensation temperature and an evaporation temperature substantially equal to R22.

Here, only points on the gas-liquid equilibrium line (R22 equivalent to 50 ° C.) 4 have been described, but points inside points A ₂ to F ₂ , that is, a temperature of 0 ° C. and a pressure of 4.044 kg / cm ² G and A working fluid with a composition that is in a gas-liquid equilibrium state at a temperature of 50 ° C and a pressure of 18.872 kg / cm ² G (both correspond to the saturated state of R22) is operated in a similar manner to use the working fluid at a temperature of approximately 0 to approximately 50 ° C. This makes it possible to obtain a condensing temperature and an evaporating temperature which are almost equal to R22 in temperature.

In the above examples, the working fluid is composed of a mixture of three types of freons, but it is of course possible to form the working fluid by a mixture of four or more types of freon including structural isomers. , Trifluoroethane about 55 to about 80% by weight, tetrafluoroethane 0 to about 45% by weight, and difluoroethane 0 to about 35% by weight, the composition range is about 0 to about 50 ° C. It is desirable because it has the same vapor pressure. Further, trifluoroethane approximately 55 to approximately 80% by weight, tetrafluoroethane 0 to
A composition range of about 45% by weight and 0 to about 30% by weight of difluoroethane is particularly desirable because it has a vapor pressure almost equal to that of R22 at all use temperatures between 0 ° C and 50 ° C. In particular, the ODP in the above combination and composition range is also 0.
It is expected to be a very promising working fluid as a substitute for R22. In addition, since such a mixture becomes a non-azeotropic mixture and has a temperature gradient in the condensation process and the evaporation process, a coefficient of performance higher than that of R22 can be expected by configuring a Lorentz cycle with a temperature difference close to that of the heat source fluid. It is.

EFFECTS OF THE INVENTION As is apparent from the above description, the present invention provides the working fluid as a mixture of two or more types of only CFCs that does not contain chlorine in the molecular structure, and by specifying the composition range thereof, (1) The influence on the stratospheric ozone layer is smaller than that of R22, and it is possible to expand the range of selection of working fluid that makes it almost none. (2) At the operating temperature of the equipment, vapor pressure similar to that of R22 can be obtained. It has, and can be used in current equipment as an alternative to R22. (3) Utilizing the property of temperature gradient of non-azeotropic mixture, R22
It has the effect that a higher coefficient of performance can be expected.

[Brief description of drawings]

FIG. 1 and FIG. 2 are diagrams showing, using triangular coordinates, the equilibrium state of a working fluid composed of a mixture of three types of freons at a constant temperature and a constant pressure. 1,3 …… Gas-liquid equilibrium line (R22 0 ° C equivalent) 2,4 ……
Vapor-liquid equilibrium line (R22 equivalent to 50 ° C).

Claims (1)

(57) [Claims] 1. A method comprising 1,1,1-trifluoroethane, tetrafluoroethane, and 1,1-difluoroethane, which are 55 to 80% by weight of 1,1,1-trifluoroethane.
45 wt% or less of the tetrafluoroethane, the 1,1-
A working fluid comprising difluoroethane in an amount of 35% by weight or less.