JP2532697B2 - 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, the depletion of the stratospheric ozone layer by CFCs has become a global environmental problem, and the CFCs that have a large ozone depletion ability in the stratosphere (hereinafter referred to as “specific CFCs”) have already been The treaty regulates the amount used and the amount produced, and there is a movement to abolish the use and production of specified CFCs in the future. Well, R22 is an ozone depletion potential (tolyl chlorofluoromethane (CCl ₃ F) stratospheric ozone depletion potential when the set to 1 stratospheric ozone depletion potential of, hereinafter referred to as ODP) is very small and 0.05, but not the specific CFCs It is expected that the amount of use will increase in the future, and now that the refrigeration and air-conditioning equipment has become widespread, the increase in the amount of use and production of R22 will have a great impact on the human living environment. Therefore, although the stratospheric ozone depletion capacity is small, it is said that it has some destructive capacity.
There is also a strong demand for early development of working fluids that can replace the above.

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 In order to solve the above problems, the present invention provides at least trifluoromethane (CHF ₃ ) and difluoromethane (CH
₂ F ₂ ) and difluoroethane (C ₂ H ₄ F ₂ ) including three types of CFCs, trifluoromethane 0 to about 50% by weight, difluoromethane 0 to about 60% by weight, difluoroethane about 40 to about 90%
Characterized in that the composition range of wt%,
In particular, a composition range of 0 to about 40% by weight of trifluoromethane, 0 to about 50% by weight of difluoromethane, and about 50 to about 85% by weight of difluoroethane is desirable.

Effect The present invention uses the above-mentioned combination to convert the working fluid into fluorocarbons (ODP = 0), difluoromethane (ODP = 0) and difluoroethane, which are CFCs having almost no ozone depletion ability and containing no chlorine in the molecular structure. (O
By making a mixture with DP = 0), the effect on the stratospheric ozone layer is even smaller than that of R22, and it is possible to almost eliminate it. In addition, according to the present invention, by setting the composition range as described above, R2 at a use temperature of a heat pump device such as an air conditioner and a refrigerator is about 0 to about 50 ° C.
It has a vapor pressure similar to that of 2, and makes it possible to provide a working fluid that can be used in current equipment as an alternative to R22. Therefore, ODP in the above-mentioned combination and composition range
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.

Now, the present invention is a mixture composed of three or more fluorocarbons including trifluoromethane. Since trifluoromethane has a low critical temperature (25.7 ° C) and a high vapor pressure, it cannot be used alone in heat pump devices such as air conditioners and refrigerators with operating temperatures of approximately 0 to approximately 50 ° C, but it is still commercially available. By using such a mixture, it becomes possible to construct a working fluid that is a practical substitute for R22.Examples Hereinafter, examples of the working fluid according to the present invention will be described with reference to the drawings. .

The figure shows the equilibrium state of a working fluid composed of a mixture of three fluorocarbons, trifluoromethane (R23), difluoromethane (R32), and 1,1-difluoroethane (R152a), at constant temperature and constant pressure in triangular coordinates. It is shown by using. 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. In addition, 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 apex of the triangular coordinate in the pattern facing the side. In the figure, 1 is temperature 0
It is the vapor-liquid equilibrium line of the mixture at ℃ and pressure of 4.044 kg / cm ² G, and this temperature and pressure correspond to the saturated state of R22. The upper line of the gas-liquid equilibrium line (corresponding to R220 0 ° C) 1 is the saturated vapor phase line,
The lower line of the gas-liquid equilibrium line (corresponding to R 220 0 ° C.) 1 represents the saturated liquidus line, and the gas-liquid equilibrium state is established in the range sandwiched by these lines. In addition, 2 is temperature 50 ℃, pressure 18.782kg / cm ²
This is the vapor-liquid equilibrium line for the mixture at G, and this temperature / pressure also corresponds to the saturated state at R22. The composition on the saturated vapor line is R
It vaporizes at a pressure higher than 22, and liquefies at the same pressure as R22.
The composition on the saturated liquidus line vaporizes at the same pressure as R22 and liquefies at a pressure lower than R22. The composition in the area between these two lines vaporizes above R22 and liquefies below R22. That is, the composition in the area between the vapor-liquid equilibrium line 2 of 50 ° C changes from the gas phase to the liquid phase at a pressure lower than R22 at 50 ° C, and at the same pressure as R22, it is 50 ° C.
The higher gas phase condenses into a liquid phase below 50 ° C. The composition in the area between the vapor-liquid equilibrium line 1 at 0 ° C changes from the liquid phase to the vapor phase at a pressure higher than R22 at 0 ° C, and the liquid phase lower than 0 ° C at the same pressure as R22. Evaporate to a gas phase above 0 ° C. When R23 is used alone, the temperature exceeds the critical temperature at 50 ° C, but a saturated state exists by forming such a mixture, and it is used in heat pump devices such as air conditioners and refrigerators at operating temperatures of approximately 0 to approximately 50 ° C. It can be used. As can be seen from the figure, R23, R32, and R152a are 0 to about 50% by weight, 0 to about 60% by weight, and about 40 to about 90% by weight, respectively.
Such a composition range 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, R23, R32 and R152a are each 0 to approximately 40% by weight,
The composition range of 0 to about 50% by weight, about 50 to about 85% by weight is R22 at all use temperatures between 0 ° C and 50 ° C.
It is particularly desirable because it has a vapor pressure almost equal to.

The composition of the working fluid at points A ₁ to F ₁ in the figure is shown in the table. Points A ₁ to C ₁ are on the saturated vapor line of vapor-liquid equilibrium line (R22 50 ° C) 2 and points D ₁ to F ₁ are on the saturated liquidus line of vapor-liquid equilibrium line (R22 50 ° C) 2 And the liquid-vapor equilibrium line (R22
Saturated liquidus line and vapor-liquid equilibrium line (R220
Since it is in the range sandwiched by both saturated liquidus lines (corresponding to ° C) 1, a vapor-liquid equilibrium state is obtained 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 first
The working fluid having the composition shown in the table achieves a saturated state or a vapor-liquid equilibrium state under the condition of the saturated vapor pressure of R22 at 0 ° C. and 50 ° C., and at an operating temperature of about 0 to about 50 ° C.,
By operating at the saturated vapor pressure of R22 at the same temperature, it becomes possible to obtain the condensation temperature and evaporation temperature that are almost the same as those of R22.

Here, only the points on the vapor-liquid equilibrium line (corresponding to R22 50 ° C.) 2 are explained, but the points inside the points A ₁ to F ₁ , that is, temperature 0 ° C. and pressure 4. A working fluid having a composition in a gas-liquid equilibrium state at a temperature of 044 kg / cm ² G, 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) was operated in the same manner to obtain approximately 0. It is possible to obtain a condensation temperature and an evaporation temperature almost equal to R22 at a usage temperature of about 50 ° C.

In the present embodiment, 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. In particular, the ODP in the above-mentioned combination and composition range is also expected to be 0, and 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 temperature and the evaporation process, a coefficient of performance higher than that of R22 can be expected by constructing a Lorentz cycle in which the temperature difference with the heat source fluid is close. Is.

EFFECT OF THE INVENTION As is clear from the above description, the present invention comprises trifluoromethane and the working fluid as a mixture composed of three or more types of fluorocarbons alone containing no chlorine in the molecular structure,
By specifying the composition range, (1) the influence on the stratospheric ozone layer is even smaller than that of R22, and it is possible to expand the range of selection of working fluids that have almost no effect.

(2) It has a vapor pressure similar to that of R22 at the operating temperature of equipment that cannot be used with trifluorometa alone, and can be used with existing equipment as an alternative to R22.

(3) By utilizing the nature of the temperature gradient of the non-azeotropic mixture, R22
It has the effect that a higher coefficient of performance can be expected.

[Brief description of drawings]

The figure is a diagram showing, using triangular coordinates, the equilibrium state of a working fluid composed of a mixture of three types of CFCs at a constant temperature and a constant pressure. 1 …… Gas-liquid equilibrium line (R22 equivalent to 0 ℃), 2 …… Gas-liquid equilibrium line (R22 equivalent to 50 ℃).

Claims (1)

(57) [Claims] 1. A trifluoromethane, difluoromethane, and 1,1-difluoroethane, which are three types of CFCs. The trifluoromethane is 50 wt% or less, the difluoromethane is 60 wt% or less, and the 1,1-difluoroethane is 40 wt% or less. Working fluid characterized by containing ~ 90% by weight.