JPH05215424A - Freezer using mixed refrigerant - Google Patents

Abstract

PURPOSE:To improve safeness by using a mixed refrigerant obtained by mixing at a prescribed mixing ratio a first incombustible refrigerant and an azeotropic mixture which shows a minimum azeotropic point under the atmospheric pressure and incombustibility by mixing a second combustible refrigerant having a boiling point higher than that of the first refrigerant and a third incombustible refrigerant having a boiling point higher than that of the second refrigerant at an azeotropic composing ratio. CONSTITUTION:R22 is used as a first incombustible refrigerant, R142b is as a second combustible refrigerant having a boiling point higher than that of the first refrigerant, and C318 is as a third incombustible refrigerant having a boiling point higher than that of the second refrigerant. The second refrigerant R142b and the third refrigerant C318 are mixed at an azeotropic composing ratio to be an azeotropic mixture which shows a minimum azeotropic point and incombustibity. In this case, the azeotropic composing ratio is R142b/C318=37.1/62.9 by weight %. As the weight % occupied by the R142b in the mixed refrigerant is 25%, the weight % of the first refrigerant R22, the second refrigerant R142b and the third refrigerant C318 is nearly 32.5:25.0:42.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus using a mixed refrigerant which does not burn even if gas leaks.

[0002]

2. Description of the Related Art In a system that uses a heat pump to cool, heat, and supply hot water, the hot water supply operation mode requires a higher refrigerant condensing temperature than the cooling and heating operation mode. Therefore, when trying to perform both of the above operation modes with a single refrigerant, the discharged refrigerant temperature rises abnormally (for example, when R22 is used as the refrigerant), or sufficient cooling / heating capacity cannot be obtained (for example, the refrigerant). (When R12 is used as). Therefore, as described in, for example, Japanese Patent Application Laid-Open No. 61-55562, a mixed refrigerant in which two kinds of refrigerants having different boiling points are mixed is used, thereby preventing the cooling / heating capacity from being lowered and in the hot water supply operation mode. Measures are taken to obtain hot water. In this case, conventionally, a mixed refrigerant of R22 (75% by weight) and R114 (25% by weight) has been used, but in recent years, the use of R114 is considered unfavorable due to the chlorofluorocarbon regulations, and its replacement Use of R142b [ethane system, molecular formula CH ₃ -CClF ₂ , molecular weight 100.50, boiling point -9.8 ° C] is being investigated as a product.

[0003]

However, the above-mentioned refrigerant R
142b is non-flammable when present in a non-combustible gas in a proportion less than or equal to a certain proportion, but exhibits flammability alone or when present in the non-combustible gas in a proportion or more than a certain proportion. .. Therefore, if the refrigerant circuit is filled with a mixed refrigerant of R22 (75 wt%) and R142b (25 wt%) and this ratio is maintained, there is no problem, but if gas leakage occurs for some reason in the refrigerant circuit, The following problems occur. That is, when a gas leak occurs, R22 (boiling point-40.82 ° C), which has a low boiling point, selectively leaks, and the ratio of R142b in the leaked mixed refrigerant, that is, the mixed refrigerant remaining in the system is as shown by the curve in FIG. First about
It gradually increases from 10% to 68 when the leak rate exceeds about 80%.
Enter a flammable area of over%. Therefore, the mixed refrigerant that leaks after that is highly likely to catch fire or explode, resulting in an accident. In addition, when disposing of the refrigeration system due to deterioration, it is necessary to extract the mixed refrigerant in the system with a vacuum pump in relation to the above-mentioned CFC regulations, but in this case as well, the R142b If the ratio is high, the same fear occurs. In addition, the area below the curve of FIG. 3, that is, the value obtained by integrating the weight% of R142b in the leaked mixed refrigerant on the vertical axis by the refrigerant leak rate on the horizontal axis is the ratio of R142b in the mixed refrigerant at the time of filling, which is 25 weight%. Equivalent to%. Therefore, an object of the present invention is to provide R14
Focusing on combustible refrigerants such as 2b that make an incombustible azeotrope with a specific refrigerant, the ratio of the combustible refrigerant in the mixed refrigerant that remains in the system even if gas leakage occurs in the refrigerant system. An object of the present invention is to provide a refrigeration system using a highly safe mixed refrigerant by suppressing the increase.

[0004]

In order to achieve the above object, a refrigerating apparatus using the mixed refrigerant of the present invention comprises a non-combustible first refrigerant and a second flammable second combustible refrigerant higher than the first refrigerant. An azeotropic mixture which is produced by mixing a refrigerant and a third refrigerant which has a higher boiling point than the second refrigerant and is nonflammable at an azeotropic composition ratio, which exhibits a minimal azeotropic point under atmospheric pressure and is nonflammable. It is characterized in that a mixed refrigerant obtained by mixing the above is mixed at a predetermined mixing ratio.

[0005]

In the refrigeration system using the above mixed refrigerant, even if the first refrigerant, which has a low boiling point and is incombustible, selectively leaks due to gas leakage in the refrigerant system, after the first refrigerant leaks, An azeotropic mixture having a minimum azeotropic point of the second refrigerant and the third refrigerant remains in the system, and this azeotropic mixture exhibits noncombustibility under atmospheric pressure. Therefore, even if this azeotropic mixture leaks out of the system, it does not ignite or explode, and the safety is ensured at the time of gas leakage or degassing at the time of disposal of the device.

[0006]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. In this embodiment, R22 is used as the first non-combustible refrigerant.
R as a second flammable second refrigerant having a higher boiling point than the first refrigerant.
142b is used as a third refrigerant that has a higher boiling point than the second refrigerant and is nonflammable, and C142 of the second refrigerant and C318 of the third refrigerant are mixed at an azeotropic composition ratio and under atmospheric pressure. It is an azeotropic mixture that exhibits a minimum azeotropic point and nonflammability. The above-mentioned azeotropic composition ratio is R142b / C318 = 37.
Since it is 1 / 62.9, and the weight percentage of R142b in the mixed refrigerant of the embodiment is 25%, the first refrigerant R22 and the second refrigerant R1
The weight% ratio of 42b and the third refrigerant C318 is approximately 32.5: 25.0: 42.5. The physical properties of the three types of refrigerants are as follows. First refrigerant R22 [methane, molecular formula CHClF _2, molecular weight 86.4
7, boiling point-40.82 ℃] Refrigerant R142b [ethane system, molecular formula CH ₃ -CClF ₂ , molecular weight
100.50, boiling point-9.8 ° C] 3rd refrigerant C318 [cyclic C ₄ F ₈ (cyclobutane fluoride), molecular weight 200.03, boiling point-5.85 ° C]

In the refrigerating apparatus using the above mixed refrigerant,
First, the case where gas leakage occurs in the refrigerant circuit will be described. Second refrigerant R142b in the mixed refrigerant filled in the refrigerant circuit
% By weight is 25% as described above. At the initial stage of the leakage, the low boiling point first refrigerant R22 selectively leaks out, and the second refrigerant R22 in the circuit
Azeotropic mixture of refrigerant R142b and third refrigerant C318 (R142b / C31
8 = 37.1 / 62.9) is left, the weight% of R142b in the mixed refrigerant in the refrigerant circuit is the progress of leakage as shown by the curve in FIG.
Increases with (increased refrigerant leakage rate). R22 which leaks out here is nonflammable, so there is no risk of ignition or explosion. When the refrigerant leakage rate reaches approximately 70%, all of the first refrigerant R22 leaks out, and thereafter, only the azeotropic mixture of the second / third refrigerant R142b / C318 leaks out, so that it remains in the refrigerant circuit. The weight% of R142b in the mixed refrigerant also shows 37.1%, which is equal to the azeotropic composition ratio, as shown in the horizontal part on the right side of the curve in FIG. And since this azeotropic mixture is nonflammable as described above,
Even if it leaks out, it does not catch fire or explode, and there is no risk of ignition or explosion even when degassing with a vacuum pump when discarding the refrigeration system in which only the azeotrope remained due to the leak.
In other words, safety is ensured when gas is leaked or gas is removed when the device is discarded, and the safety of the refrigeration system itself is improved. The area below the curve in FIG. 1 corresponds to 25%, which is the weight% of R142b in the mixed refrigerant at the beginning of filling. The composition ratio of the azeotropic mixture is R142b / C318 =
It is 37.1 / 62.9, but even with a mixture before and after this composition ratio,
The same effect as described above can be obtained.

Next, the function of the mixed refrigerant in the refrigeration system will be described. However, the mixed refrigerant used in the refrigerating apparatus has a small composition ratio of the azeotropic mixture, and the weight% of R142b is about 10%. FIG. 2 shows a refrigerant circuit of a heat pump type refrigerating apparatus using this mixed refrigerant. This refrigerant circuit includes a switching port C of the four-way switching valve 2, an outdoor heat exchanger 3, a liquid receiver 5, an air conditioner. The indoor unit 7, which is the heat exchanger for the vehicle, and the switching ports H of the four-way switching valve 2 are sequentially piped from 10b to 10b.
The circulation port is connected by e, and the discharge port of the compressor 1 and the inflow port I of the four-way switching valve 2 are connected to the outflow port O of the four-way switching valve 2 and the compressor 1 by a pipe 10a provided with the first opening / closing valve 11. The suction ports are connected to each other by a pipe 10f having an accumulator 8 interposed therebetween. Further, the pipe 10c on the outdoor heat exchanger 3 side of the liquid receiver 5 is provided with the first expansion valve 4 for adjusting the capacity during heating, and the pipe 10d on the indoor heat exchanger 7 side is provided with the second expansion valve 4 for adjusting the capacity during cooling. The expansion valves 6 are provided respectively. Further, a hot water storage unit 9 which is a heat exchanger for boiling water is connected between the discharge port of the compressor 1 and the liquid receiver 5 by a pipe 10g and a pipe 10h provided with a second opening / closing valve 12.

In the refrigerant circuit shown in FIG. 2, the mixed refrigerant is
It behaves as a non-azeotropic mixed refrigerant in which the first refrigerant R22 is the low boiling first component and the second / third refrigerant R142b / C318 azeotrope is the high boiling second component. Then, by adjusting the opening degree of the first and second expansion valves 4 and 6, the amount of liquid refrigerant stored in the accumulator 8 is increased or decreased, and the composition of the refrigerant circulating in the refrigerant circuit is changed accordingly, depending on the heating / cooling and hot water supply. The ability control is performed as follows.

First, in the cooling operation mode, the first on-off valve 1
Open only 1, and set the four-way selector valve 2 to port I, C / port H,
O is switched to communicate with each other, and the refrigerant gas discharged from the compressor 1 is circulated as indicated by the broken line arrow to be condensed and radiated by the outdoor heat exchanger 3 while being evaporated and absorbed by the indoor unit 7 so that the inside of the room is To cool. At this time, the first expansion valve 4 is fully opened, and the opening degree of the second expansion valve 6 is adjusted so that the superheat degree of the refrigerant after passing through the indoor unit (7) becomes appropriate. Then, the refrigerant liquid is not stored in the accumulator 8, and all the mixed refrigerant circulates in the refrigerant circuit. When the cooling load increases from this state, the opening degree of the second expansion valve 6 is increased to control the refrigerant after passing through the indoor unit to be moist. Then, the moist refrigerant flowing into the accumulator 8 is separated into gas and liquid, and the liquid refrigerant is stored. The composition of the liquid refrigerant separated from the moist refrigerant, that is, the liquid refrigerant to be stored is a total rate soluble type in which the temperature with the R22b as the first component and the R142b / C318 azeotrope as the second component is plotted on the vertical axis. As can be seen from the vapor-liquid equilibrium diagram in Fig. 1, a large amount of high boiling azeotrope (second component) is contained. Therefore, the refrigerant circulating in the refrigerant circuit is
On the contrary, a large amount of R22 (first component) having a low boiling point is contained, and the cooling capacity is increased accordingly. The amount of the refrigerant liquid stored in the accumulator 8 reduces the opening degree of the second expansion valve 6 and increases the dryness of the refrigerant after passing through the indoor unit,
It can be reduced by evaporating the stored refrigerant liquid, which reduces the cooling capacity to the initial state.

Next, in the heating operation mode, the four-way switching valve 2
Are switched so that the ports I and H / ports C and O are communicated with each other, and the refrigerant gas discharged from the compressor 1 is circulated as indicated by the solid line arrow to be condensed and radiated by the indoor unit 7, while the outdoor heat exchanger is also used. In 3 heats the room by evaporating and absorbing heat. At this time, the second expansion valve 6 is fully opened and the first expansion valve 4 is opened.
When the liquid refrigerant containing a large amount of the azeotrope is stored in the accumulator 8 by increasing the opening degree of, the heating capacity is increased.

Further, in the hot water supply mode, the four-way switching valve 2 is set to the same position as in the heating operation mode, the first opening / closing valve 11 is closed, the second opening / closing valve 12 is opened, and the refrigerant gas discharged from the compressor 1 is It is sent to the hot water storage unit 9 through the pipe 10g as indicated by the one-dot chain line arrow, and is circulated as shown by the solid line arrow from the pipe 10h through the liquid receiver 5. In this case, since the hot water must be boiled in the hot water storage unit 9, it is necessary to circulate the high boiling point azeotropic mixture without storing it in the accumulator 8. Therefore, the second expansion valve 6 is fully opened, the opening degree of the first expansion valve 4 is adjusted so that the degree of superheat of the refrigerant after passing through the outdoor heat exchanger (3) becomes appropriate, and all the mixed refrigerants are cooled by the refrigerant. Circulate in the circuit. As a result, the azeotropic mixture of R142b / C318 condenses in the hot water storage unit 9 of the refrigerant circuit and boils the hot water as a high temperature heat source. Further, in order to reduce the boiling water capacity, the opening degree of the first expansion valve 4 may be increased to store the refrigerant liquid containing a large amount of the azeotropic mixture in the accumulator 8.

As described above, if the mixed refrigerant composed of R22 and R142b / C318 azeotrope of this embodiment is used in the refrigerating apparatus, the accumulator can be adjusted by adjusting the opening of the first and second expansion valves 4 and 6. It is possible to increase or decrease the amount of the azeotrope mixture stored in 8 and to increase or decrease the amount of R22 in the refrigerant circulating in the refrigerant circuit in accordance with this, and to perform appropriate capacity control according to cooling and heating and hot water supply. .. In addition, since the azeotropic mixture is non-flammable as described above, safety is ensured at the time of gas leakage and degassing at the time of discarding the refrigeration system, and the safety of the refrigeration system itself is improved.

In the above embodiment, the case where R22, R142b, and C318 are used as the first, second, and third refrigerants, respectively, has been described. However, the kinds of the respective refrigerants are not limited to these, and the composition ratio thereof is also used. It is not limited to the examples.

[0015]

As is clear from the above description, the refrigerating apparatus of the present invention includes a non-combustible first refrigerant, a second combustible refrigerant having a higher boiling point than the first refrigerant, and the second refrigerant. It is produced by mixing an azeotropic composition ratio with a third refrigerant that has a higher boiling point and is nonflammable, and is mixed at a predetermined mixing ratio with an azeotropic mixture that exhibits a minimal azeotropic point and nonflammability under atmospheric pressure. Since a mixed refrigerant is used, by adjusting the opening degree of the expansion valve of the refrigeration system, etc., the ratio of the first refrigerant contained in the refrigerant circulating in the refrigerant circuit is increased or decreased to perform appropriate capacity control according to heating / cooling or hot water supply. In addition, the non-flammable azeotropic mixture ensures the safety of gas leakage and degassing at the time of disposal, and can improve the safety of the refrigerating apparatus itself.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a refrigerant leak rate in a mixed refrigerant and a ratio of R142b in the leaked refrigerant according to an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of a refrigerating apparatus using the mixed refrigerant.

FIG. 3 is a diagram showing a relationship between a refrigerant leakage rate in a conventional mixed refrigerant and a ratio of R142b in the leakage refrigerant.

[Explanation of symbols]

1 ... Compressor, 2 ... Four-way switching valve, 3 ... Outdoor heat exchanger, 4,
6 ... First and second expansion valves, 7 ... Indoor unit, 8 ... Accumulator, 9 ... Hot water storage unit.

Claims (1)

[Claims] 1. An azeotropic composition of a non-flammable first refrigerant, a second flammable second refrigerant having a higher boiling point than the first refrigerant, and a third non-flammable refrigerant having a higher boiling point than the second refrigerant. Produced by mixing in a ratio, it exhibits a minimum azeotropic point under atmospheric pressure,
A refrigeration system using a mixed refrigerant formed by mixing a non-flammable azeotropic mixture with a predetermined mixing ratio.