JPH03170587A - Working fluid - Google Patents

Abstract

PURPOSE:To obtain a working fluid which scarcely affects the ozonosphere and serves as an R22 substitute by mixing difluoromethane, tetrafluoroethane, and difluoroethane. CONSTITUTION:A working fluid containing at least three hydrofluorocarbons, i.e., 20-60wt.% difluoromethane, at most 80wt.% tetrafluoroethane, and at most 65wt.% difluoroethane. As the working fluid, particularly those comprising 25-50wt.% difluoromethane, at most 75wt.% tetrafluoroethane, and at most 65wt.% difluoroethane are preferably used. The working fluid having a composition in the above-mentioned range has a vapor pressure comparable to that of R22 at about 0-50 deg.C, which is the service temperature of a heat pump of, e.g. an air conditioner or a refrigerator, and it can be employed as an R22 substitute in machinery now in use.

Description

[Detailed Description of the Invention] Industrial Fields of Application The present invention relates to working fluids used in heat pump devices such as air conditioners and refrigerators. as fluorocarbons (hereinafter referred to as R○○ or R○○
Halogenated hydrocarbons (denoted as ○) are known, and are usually used at a condensation temperature and/or evaporation temperature in the range of approximately 0 to approximately 50°C.Among them, chlorodifluoromethanes (CHCIFs, R22) Although it is widely used as a working fluid in home air conditioners, building air conditioners, and large refrigerators, it is still a problem that the invention attempts to solve.In recent years, depletion of the stratospheric ozone layer by fluorocarbons has become a global environmental problem. The use and production of fluorocarbons (hereinafter referred to as specified fluorocarbons), which have a large ability to deplete stratospheric ozone, has already been regulated by international treaties.
Now, there is a movement to abolish production of R22.
) is 0. 05, and although it is not a specified CFC, usage is expected to increase in the future.
Although it is expected that an increase in the amount of R22 used and produced will have a greater impact on the human living environment, it is therefore expected that R22, which has a small ozone depletion ability in the lower stratum of the earth, will have a small depleting ability. There is also a strong need for the early development of alternative working fluids.

The present invention was attempted in view of the above-mentioned problems, and provides a working fluid that has little effect on the stratospheric ozone layer and is an alternative to t,k R22.It is also a means to solve the problems. The present invention solves the above-mentioned problems by combining at least L difluoromethane (CH2F2) and tetrafluoroethane (
Contains three types of fluorocarbons: C2HeFd and difluoroethane (C2H4F2) Difluoromethane approximately 20 to approximately 6
It is characterized by a composition range of 0% by weight, tetrafluoroethane O to approximately 80% by weight κ, difluoroethane 0 to approximately 65% by weight, particularly difluoromethane approximately 2% by weight.
Although a range of 5% to approximately 50% by weight of tetrafluoroethane O to approximately 75% by weight of difluoroethane O to approximately 65% by weight is preferable, the present invention is advantageous in that the above-mentioned combination allows the working fluid to have most of its ozone depleting ability. None＼ Difluoromethane (○DP==0), which is a fluorocarbon that does not contain chlorine in its molecular structure,
By forming a mixture of tetrafluoroethane (○DP=0) and difluoroethane (○DP=0), the effect on the stratospheric ozone layer is even smaller than that of R22.
However, by incorporating the above-mentioned range, the present invention can reduce air conditioners.
L R2 has a vapor pressure similar to that of R22 at approximately 0 to approximately 50°C, which is the operating temperature of heat pump devices such as refrigerators.
This makes it possible to provide a working fluid that can be used in current equipment as an alternative to 2.

Therefore, ODP in the above combination and group precept range is also O
It is predicted that it will be a very promising working fluid as a replacement for R22.In addition, such a mixture will be a non-azeotropic mixture, and will have a temperature gradient during the condensation and evaporation processes. By paying close attention to the Lorenz cycle, a higher performance coefficient than R22 can be expected.

In general, fluorocarbons have the ability to destroy stratospheric ozone.
The effect of global warming tends to increase as the ODP value increases. The global warming effect is estimated to be on the same level as R22 or less than R22, and it is possible to minimize the contribution to global warming, which has recently become a worldwide problem. An example of the working fluid will be explained with reference to the drawings, as shown in Figure 1.
1. 2-tetrafluoroethane (R134a)
, 1,1-difluoroethane (Rl52a) The working fluid Q is composed of a mixture of three types of fluorocarbons: At each vertex, single substances are arranged counterclockwise from the upper vertex as the base point in descending order of boiling point. It is expressed as the ratio of the distance between the point and the side of the triangle.In this case, the distance between the point and the side of the triangle (as the distance between the point and the side of the triangle) In the figure 11
yo Temperature 0℃・Pressure 4. This is the vapor-liquid equilibrium line of the mixture at 044 kg/cm"G, and this temperature and pressure are R2
This corresponds to the saturated state of 2. The vapor-liquid equilibrium line (R22 0℃
(equivalent) The upper line of l is the saturated gas phase, the vapor-liquid equilibrium line (R22
(equivalent to 0°C) The lower line represents the saturated liquidus line, and the area between these lines is considered to be in a vapor-liquid equilibrium state.
Also 2 (temperature 50℃, pressure 18.7 8 2kg
This is the vapor-liquid equilibrium line of the mixture at /cm''G, and this temperature and pressure also correspond to the saturated state of R22. It is desirable to have a vapor pressure of approximately 1 as that of R22 at a usage temperature of approximately 0 to approximately 50° C. (1, moreover, GQ R 3 SRl34a and R1
52a is approximately 25 to 50% by weight, respectively. 0~approximately 75 weight gourd 0~approximately 65 weight 1% range ζ&
It is particularly desirable because it has a dormer pressure almost equal to that of R22 at all operating temperatures between 01 and 50t (Table 1 shows the introduction of the working fluid at points A1 to F1 in FIG. 1). Points A+ to C+ are the vapor-liquid equilibrium line (R22
It is on the saturated gas phase line of 2 (equivalent to 50t) and is sandwiched between the saturated gas phase line of vapor-liquid equilibrium line (equivalent to R22 0t) 1 and the saturated liquidus line of vapor-liquid equilibrium line (equivalent to R22 0t) 1. The temperature is 0℃ and the pressure is 4. 04
At 4 kg/cm'G (corresponding to the saturated state of R2), a gas-liquid equilibrium state is reached. In addition, points D1 to F1 are on the saturated liquid line of the vapor-liquid equilibrium line (equivalent to R220℃) 1, and the saturated vapor phase line and vapor-liquid equilibrium line (equivalent to R22 5Ot) 2 of the vapor-liquid equilibrium line (equivalent to R22 5Ot) 2 It must be within the range between the lines of the saturated liquidus line. 782kg/cm”G (R22
Therefore, the working fluid Lt, which has the composition shown in Table 1, is in a gas-liquid equilibrium state.
By realizing a saturated state or a vapor-liquid equilibrium state under the conditions of the saturated vapor pressure of R22 at 0°C and 50°C, and operating at the saturated vapor pressure of R22 at the same temperature at a usage temperature of approximately 0 to approximately 50°C, Condensing temperature almost equal to R22
It is possible to obtain the evaporation temperature. Point A1 is only explained about the points on the vapor-liquid equilibrium line (R22, equivalent to 0°C) 1 or the vapor-liquid equilibrium line (R22, equivalent to 50°C) 2. ~A point inside point F1,
In other words, the temperature is 0°C, the pressure is 4.044 kg/cm2G, and the temperature is 50°C, the pressure is 18.782 kg/c. m
By performing the same operation on a working fluid that has a gas-liquid equilibrium state at 2G (both correspond to the saturated state of R22), the condensation temperature is almost equal to R22 at a usage temperature of about 0 to about 50°C This makes it possible to obtain the evaporation temperature.

Figure 2 C R32, 1. l, 2. 2-
A working fluid composed of a mixture of three types of fluorocarbons: tetrafluoroethane (R134) and Rl52a.

The equilibrium state at constant temperature and constant pressure is shown using triangular coordinates. In this triangular coordinate, R152a has a lower standard boiling point at atmospheric pressure than R134. In relation to Figure 1, at each vertex of the triangle
Counterclockwise from the upper vertex R32, R134
, R152a(7). Second
In the figure, 31. Temperature 0°C/Pressure 4. 044kg
/cm”G is the vapor-liquid equilibrium line of the mixture, and 4
(Temperature: 50℃・Pressure: 18.782kg/crn
In this case, R32, R134, and R152a are each approximately 3o~
Approximately 60% by weight. 0 to approximately 7o weight exceeded 0 to approximately 65% by weight <. R32, R134 and RI5 are desirable because they have almost the same vapor pressure as R22.
2a is about 35 to about 5o weight% 0 to about 65 weight 1
Table 2 shows the working fluid range from point A2 to point F2 in FIG. 2, which is particularly desirable. Point A2 to point C2 is the vapor-liquid equilibrium line (R22
Points D2 to E2 are on the saturated liquidus line of the vapor-liquid equilibrium line (R22, equivalent to 50°C) 4, and both are on the saturated vapor line of the vapor-liquid equilibrium line (R22, equivalent to 50°C) 3. It must be in the range between the phase line and the vapor-liquid equilibrium line (equivalent to R22 0℃) 3 and the saturated liquidus line. Also, point F2 is on the saturated liquidus line of the vapor-liquid equilibrium line (R22, equivalent to 0°C) 3, and the saturated vapor phase line of the vapor-liquid equilibrium line (R22, equivalent to 50°C) 4. Gas-liquid equilibrium line (R22 equivalent to 50℃) 4
Since it is in the range between the lines of the saturated liquidus line, the temperature is 50°C and the pressure is 18. 782kg/cm2G (R2
(corresponding to the saturated state of 2), the state is in vapor-liquid equilibrium.

Therefore, the working fluid with the composition shown in Table 2 is 0
By realizing a saturated state or a vapor-liquid equilibrium state under the conditions of the saturated vapor pressure of R22 at 50°C and 50°C, and operating at the saturated vapor pressure of R22 at the same temperature at a usage temperature of about 0 to about 50°C, R22 The condensing temperature is almost equal to
Here, it is possible to obtain the evaporation temperature.
Power loss explained only about the points on the vapor-liquid equilibrium line (R22, equivalent to 0°C) 3 or the vapor-liquid equilibrium line (R22, equivalent to 50°C) 4.
Temperature 0℃, pressure 4.044kg/cm2G and temperature 50
℃・Pressure 18.782kg/cm"G (both R22
By performing the same operation for a working fluid that has a gas-liquid equilibrium state (corresponding to the saturated state of
It is possible to obtain condensation and evaporation temperatures almost equal to R22 at a usage temperature of approximately 0 to approximately 50°C.

In the above embodiments, the working fluid is composed of a mixture of three types of fluorocarbons.Of course, the working fluid can also be composed of a mixture of four or more types of fluorocarbons, including structural isomers. In this case, difluoromethane approximately 20 to approximately 60% by weight tetrafluoroethane O to approximately 80% by weight
Weight κ Difluoroethane O ~ Approximately 65% by weight R2 at the operating temperature of approximately 0 to approximately 50°C
It is desirable because it has a vapor pressure almost equal to that of 2 (t), difluoromethane (approximately 25 to approximately 50% by weight), tetrafluoroethane (0 to approximately 75% by weight), difluoroethane (O) to approximately 65% by weight. It is particularly desirable because it has almost the same vapor pressure as R22 at all operating temperatures between 0°C and 50°C. Even if the mixture is a promising working fluid, it becomes a non-azeotropic mixture, and by constructing a Lorenz cycle with a temperature gradient in the condensation process and the evaporation process, the temperature difference between the heat source fluid and the heat source fluid is made close to each other. Although it is expected to have a higher performance coefficient than R22, it is clear from the above explanation that the working fluid of the present invention is made from three or more types of fluorocarbons that do not contain chlorine in their molecular structure. By specifying the range of mixtures and mixtures that can be used, (1) It is possible to expand the range of choices for working fluids that have even less impact on the stratospheric ozone layer than R22, and have almost no effect on the stratospheric ozone layer. (2) It can be used in current equipment as a substitute for LA R22, which has a vapor pressure similar to that of R22 at the operating temperature of the equipment. (3) R2
It has the effect that a higher coefficient of performance can be expected than 2.

[Brief explanation of the drawing]

Figures 1 to 2 (This is a mixture of three types of fluorocarbons. 1, 3... Vapor-liquid equilibrium line (R22 equivalent to 0°C), 2
, 4... Gas-liquid equilibrium line (R22 equivalent to 50°C).

Claims (2)

[Claims] (1) A working fluid containing at least three types of fluorocarbons: 20 to 60% by weight of difluoromethane, 80% by weight or less of tetrafluoroethane, and 65% by weight or less of difluoroethane. (2) A working fluid characterized by containing 25 to 50% by weight of difluoromethane, 75% by weight or less of tetrafluoroethane, and 65% by weight or less of difluoroethane.