JP2012236884A - Mixed refrigerant and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixed refrigerant having a zero value of ODP and a small value of GWP, and to provide an air conditioner using the refrigerant.SOLUTION: The mixed refrigerant is a mixed refrigerant consisting of two kinds of refrigerants of R32 of a first refrigerant and R134a or R1234yf of a second refrigerant, regulated so that the mixed proportion of the first refrigerant may be higher than the mixed proportion of the second refrigerant. Preferably, the mixed proportion of the first refrigerant is 80-90 wt.%. As a result, the mixed refrigerant having the zero value of the ODP and the small value of the GWP is provided, and the air conditioner is provided by using the refrigerant.

Description

  The present invention relates to a mixed refrigerant and an air conditioner using the mixed refrigerant.

  Conventionally, in an air conditioner for a tropical region corresponding to a high outside air temperature environment with a maximum outside air temperature of about 52 ° C., R22 is used as a working refrigerant. As shown in the list of physical properties in FIG. 1, R22 is scheduled to be abolished in 2020 in developed countries because the ozone depletion potential (ODP) is not zero. For this reason, there is an urgent need to shift to an alternative refrigerant having zero ODP. As alternative refrigerants with zero ODP, mixed refrigerants such as R410A and R407C and single refrigerants such as R32 are generally known.

  R410A is generally used in a temperate region where the outside air temperature is not high. As shown in FIG. 1, this R410A has a relatively low critical temperature of 71.4 ° C., so the cooling capacity and coefficient of performance at high outside air temperature (high condensation temperature) are extremely reduced, and it is intended for the tropical region. When used in an air conditioner, there is a problem that the efficiency is remarkably deteriorated. In recent years, a refrigerant with a small global warming potential (GWP), which is an index for comparing the degree of impact of global warming due to greenhouse gases, has been desired from the consideration of the global environment, but the GWP of R410A is 2090. There is a disadvantage that it is larger than the G22 (= 1810) of R22.

  As shown in FIG. 1, R407C is a non-azeotropic refrigerant mixture having a high critical temperature of 86.0 ° C. and suitable for use in a high outside air temperature environment than R410A, but having a relatively large temperature gradient of about 6 deg. There are disadvantages that it is difficult to handle because of certain things and GWP is relatively high.

  As shown in FIG. 1, R32 is a single refrigerant that is also included in R410A, and generally has a performance equal to or higher than R22. However, since the condensing pressure and the discharge temperature are relatively high, it is difficult to use the conventional air conditioner using refrigerants such as R410A and R22.

  For this reason, it has been desired to develop a refrigerant having zero ODP and smaller GWP than the conventional R22. As such a refrigerant, when a mixed refrigerant mainly composed of R32 having a relatively high refrigerating capacity is considered, the condensation pressure and discharge temperature, which are disadvantages of R32, are reduced, and the temperature gradient is at least about 2.5 deg. It is necessary to keep it below.

  This invention is made | formed in view of the above, Comprising: It aims at providing the mixed refrigerant which ODP is zero and GWP is small, and an air conditioner using the same.

  In order to solve the above-described problems and achieve the object, the mixed refrigerant according to claim 1 of the present invention is composed of two kinds of refrigerants, that is, the first refrigerant R32 and the second refrigerant R134a or R1234yf. The mixed refrigerant is characterized in that the mixing ratio of the first refrigerant is larger than the mixing ratio of the second refrigerant.

  Moreover, the mixed refrigerant according to claim 2 of the present invention is characterized in that, in the mixed refrigerant according to claim 1 described above, the mixing ratio of the first refrigerant is 80 to 90 wt%.

  An air conditioner according to a third aspect of the present invention uses the mixed refrigerant according to the first or second aspect described above.

  The mixed refrigerant according to the present invention is a mixed refrigerant composed of two types of refrigerants, that is, the first refrigerant R32 and the second refrigerant R134a or R1234yf, and the mixing ratio of the first refrigerant is Since it is larger than the mixing ratio of the second refrigerant, as shown in FIG. 1, there is an effect that the ODP is zero and the GWP can be made smaller than the conventional R22 GWP (= 1810).

  Further, according to the air conditioner according to the present invention, since the above-described mixed refrigerant is used, it is possible to reduce the condensing pressure and the discharge temperature, which are disadvantages of R32, and to suppress the temperature gradient to at least about 2.5 deg or less. There is an effect that can be done. Further, the cooling capacity when the above-described mixed refrigerant is used (when the same air conditioner is operated under the same condensing temperature, evaporation temperature, superheat degree, and supercooling condition) is higher than R22.

FIG. 1 is a list illustrating physical properties of a mixed refrigerant according to the present invention and a conventional refrigerant. FIG. 2 is a diagram illustrating an example of the relationship between the saturated vapor pressure and the condensation temperature. FIG. 3 is a comparison diagram of the discharge temperature when a condensation temperature of 68 ° C. is assumed. FIG. 4 is a comparison diagram of refrigerating capacity when a condensation temperature of 68 ° C. is assumed. FIG. 5 is a comparison chart of coefficient of performance when a condensation temperature of 68 ° C. is assumed. FIG. 6 is a refrigerant circuit diagram showing an embodiment of an air conditioner using a mixed refrigerant according to the present invention. FIG. 7 is a ph diagram for the circuit of FIG. FIG. 8 is a diagram showing the composition of the liquid refrigerant in the two-phase region in the condenser when a condensation temperature of 68 ° C. is assumed.

  Embodiments of a mixed refrigerant and an air conditioner using the same according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

[Mixed refrigerant]
First, the mixed refrigerant according to the present invention will be described.
The mixed refrigerant according to the present invention is a mixed refrigerant composed of two kinds of refrigerants, that is, R32 which is a first refrigerant and R134a or R1234yf which is a second refrigerant, and the mixing ratio of the first refrigerant is the first refrigerant. It is larger than the mixing ratio of the two refrigerants. Below, the case of the mixed refrigerant which consists only of R32 and R134a will be described as an example.

  In the column of “R32 + R134a” in FIG. 1, the physical property values of the mixed refrigerant composed only of R32 and R134a are shown for each content ratio of R32. The content ratio of R32 is three types of 90, 80, and 70 wt%. As shown in FIG. 1, the ODP of these three mixed refrigerants is zero. Moreover, GWP is 751-902, and it turns out that it is smaller than GWP of R22 (= 1810). Here, SL in FIG. 1 indicates standard conditions and assumes a condensation temperature of 48 ° C. OL shows the conditions for the tropical region and assumes a condensation temperature of 68 ° C.

FIG. 2 is a diagram illustrating an example of the relationship between the saturated vapor pressure and the condensation temperature of each refrigerant.
When considering using the mixed refrigerant of the present invention in an existing air conditioner for R410A for the tropical region, as shown in FIG. 2, the pressure when the condensation temperature is 65 ° C. or higher is It can be seen that it is necessary to mix R134a (or R1234yf) with R32 in an amount of 10 wt% or more in order to suppress the pressure to less than the desired design pressure (4.15 MPa).

  In this case, for example, if a mixed refrigerant containing 80 to 90 wt% of R32 is used and the air conditioner is operated at a condensation temperature of about 65 to 68 ° C., the pressure is about the design pressure of R410A compared to the case where R32 is used alone. Can be lowered to Moreover, as shown in FIG. 1, the high condensing pressure and discharge temperature, which are weak points of R32, can be reduced, and the temperature gradient in the evaporator can be suppressed to at least about 2.5 deg or less. That is, if the upper limit of the usable condensing temperature is up to about 68 ° C., the mixed refrigerant of the present invention containing R32 of 80 to 90 wt% can be used for existing products for the tropical region.

  FIG. 3 is a diagram comparing the discharge temperature at the time of high condensation temperature. In the figure, the notation such as R32 + R134a (90/10) indicates that R32 is a mixed refrigerant of 90 wt% and R134a is 10 wt%. As shown in FIG. 3, it can be seen that mixing R134a (or R1234yf) with R32 suppresses the discharge temperature. Note that FIG. 3 is obtained assuming a method that does not use the liquid injection method described later.

  FIG. 4 is a diagram comparing the refrigeration capacity at high condensing temperature (theoretical value: when the compressor displacement volume / rotation speed is the same), and is represented by the capacity when R22 is 100%. As shown in FIGS. 4 and 1, it can be seen that the refrigerant having a higher refrigeration capacity than R22 (the refrigerant having R410A, R32 and R32 + R134a of 20 wt% or less) has a higher pressure than R22. In addition, in the mixed refrigerant of the present invention consisting only of R32 and R134a, it can be seen that the content ratio of R32 needs to be at least 80 wt% in order to obtain a refrigerating capacity equal to or higher than R410A.

  FIG. 5 is a diagram comparing the coefficient of performance (theoretical value) at a high condensation temperature. As shown in FIG. 5, among the refrigerants having higher refrigerating capacity than R22, it can be seen that the coefficient of performance of R410A is particularly low and the operation efficiency is poor. The coefficient of performance of the mixed refrigerant of the present invention consisting only of R32 and R134a is almost the same as the coefficient of performance of R32.

[Air conditioner using mixed refrigerant]
Next, an air conditioner using the mixed refrigerant according to the present invention will be described with reference to FIGS.

  FIG. 6 is a refrigerant circuit diagram during cooling operation. As shown in FIG. 6, the refrigeration cycle circuit of the air conditioner 10 according to the present invention includes a compressor 12, a condenser (outdoor unit) 14, a decompression means 16, an evaporator (indoor unit) 18, and a four-way system. It consists of a valve 20. As the working refrigerant, a mixed refrigerant consisting of only R32 and R134a or only R32 and R1234yf is used.

  This refrigeration cycle circuit separates R134a (or R1234yf) rich liquid refrigerant from a predetermined position of the condenser 14 and injects the separated liquid refrigerant into the intermediate pressure of the compressor 12.

  Specifically, the gas-liquid separator 22 is attached at a position where the volume ratio A% :( 100−A)% of the condenser 14 is obtained, whereby the condenser 14 has a volume ratio of A% with respect to the whole condenser. The first condenser 14a and the (100-A)% second condenser 14b are configured. As the attachment position of the gas-liquid separator 22, it is necessary to select a position where the refrigerant is in the two-phase region under the assumed operation conditions. An example is a case where a mixed refrigerant composed of only R32 and R134a and the mixing ratio of R32 is 80 wt%. When operating at a condensing temperature of 68 ° C, the liquid injection is controlled so that the discharge temperature is 90 ° C, which is the same as the equipment using the conventional refrigerant R410A, and the degree of supercooling at the condenser outlet is a general refrigeration cycle. When the entire refrigeration cycle is controlled to be the same 5 deg, as shown in FIG. 7, the ratio of energy released by the refrigerant in the condenser is as follows: gas region: 24%, two-phase region: 69%, supercooling region: 7% It becomes. Since the heat exchange amount per unit volume of the condenser can be regarded as substantially uniform, when A is determined from the volume ratio of the heat exchanger described above, the value of A is in the range of 24 to 93%. In addition, since the physical property of the refrigerant (the ratio of the heat release amount) varies depending on the mixing ratio, it is desirable to select a position corresponding to the mixing ratio.

  In addition, the mixed refrigerant passing through the condenser is liquefied first in the refrigerant having a higher boiling point. Here, FIG. 8 shows the composition of the liquid-phase refrigerant in the refrigerant in the two-phase region in FIG. 7, and the proportion of the high-boiling refrigerant increases in the two-phase region closer to the inlet side of the condenser. It is shown that. Therefore, when taking out the liquid of B section (refer FIG. 7) in a two-phase area | region, it is desirable to arrange | position said A to the inlet side of a condenser.

The operation of the above configuration will be described.
The mixed refrigerant from the compressor 12 enters the first condenser 14 a through the pipe 26 and is separated into gas and liquid by the gas-liquid separator 22. The R134a (or R1234yf) rich liquid refrigerant accumulated in the gas-liquid separator 22 is injected into the compressor 12 through the flow rate adjustment valve 24 and through the pipe 32. On the other hand, the saturated vapor refrigerant separated by the gas-liquid separator 22 enters the evaporator 18 from the second condenser 14 b through the pipe 28 and the decompression means 16. The ratio of R32 as the refrigerant entering the evaporator 18 is increased. The refrigerant from the evaporator 18 is sent to the compressor 12 through the pipe 30.

  Thus, by separating in advance the liquid refrigerant of R134a (or R1234yf) that is liable to liquefy first from the two-phase region, the ratio of R32 in the refrigerant that goes to the evaporator 18 becomes larger, and the temperature at the evaporator 18 The gradient can be reduced. For this reason, according to the air conditioner 10 of this invention, the influence of the fault which a non-azeotropic refrigerant mixture has can be made small.

  On the other hand, since the refrigerant injected into the compressor 12 is in a liquid state, the temperature of the refrigerant finally discharged can be suppressed by the heat that it vaporizes. Further, since this liquid refrigerant contains a larger amount of R134a (or R1234yf) having a lower discharge temperature than R32, the liquid refrigerant has a greater discharge temperature suppression effect than injection of a liquid refrigerant that does not contain much R134a (or R1234yf).

  In the above-described embodiment, the case of the mixed refrigerant mainly composed of only R32 and R134a has been described. However, using R1234yf having similar physical properties to R134a as shown in FIGS. 1 and 2, R32 is used. And R1234yf, the same effect as in the case of the mixed refrigerant consisting only of R32 and R134a is obtained, such as ODP being zero and GWP being smaller than R22.

  As described above, the mixed refrigerant according to the present invention is a mixed refrigerant composed of two kinds of refrigerants, that is, the first refrigerant R32 and the second refrigerant R134a or R1234yf. As shown in FIG. 1, the ODP is zero and the GWP can be made smaller than the conventional R22 GWP (= 1810) because the mixing ratio of the refrigerant is larger than the mixing ratio of the second refrigerant. There is an effect that can be done.

  Further, according to the air conditioner according to the present invention, since the above-described mixed refrigerant is used, it is possible to reduce the condensing pressure and the discharge temperature, which are disadvantages of R32, and to suppress the temperature gradient to at least about 2.5 deg or less. it can. Further, the cooling capacity when the above-described mixed refrigerant is used (when the same air conditioner is operated under the same condensing temperature, evaporation temperature, superheat degree, and supercooling condition) is higher than R22.

In addition, since the condensing pressure and the discharge temperature can be reduced, operation is performed at a pressure equal to or lower than that of the refrigerant (R410A) conventionally used even at a high outside temperature where the outside temperature is 52 ° C. or higher. As a result, it is not necessary to change the design pressure of the expansion valve, piping, etc., and parts can be shared to reduce costs.

  As described above, the mixed refrigerant and the air conditioner using the mixed refrigerant according to the present invention are useful for an air conditioner for a tropical region, and in particular, the ODP of the mixed refrigerant is zero and the GWP is reduced. Suitable for

10 Air Conditioner 12 Compressor 14 Condenser (Outdoor Unit)
16 Pressure reducing means 18 Evaporator (indoor unit)
20 Four-way valve 22 Gas-liquid separator 24 Flow control valve 26, 28, 30, 32 Piping

Claims (3)

A mixed refrigerant composed of two kinds of refrigerants, that is, a first refrigerant R32 and a second refrigerant R134a or R1234yf,
A mixed refrigerant, wherein a mixing ratio of the first refrigerant is larger than a mixing ratio of the second refrigerant.   The mixed refrigerant according to claim 1, wherein a mixing ratio of the first refrigerant is 80 to 90 wt%. An air conditioner using the mixed refrigerant according to claim 1.

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