KR0184083B1 - Refrigerant mixtures - Google Patents

Abstract

The present invention relates to an azeotropic mixed refrigerant comprising 20-50 wt% of pentafluoroethane, 45-75 wt% of 1,1,1,2-tetrafluoroethane, and 5-10 wt% of C ₃ hydrocarbons selected from furopropylene or cyclofurophane. (Non-Azeotropic Refrigerant Mixtures).

The mixed refrigerant of the present invention has no possibility of destroying ozone and shows an excellent effect in terms of the freezing volume capacity of the refrigeration coefficient coefficient compressor as an alternative to the existing R-22 in a refrigerator using a suction tube heat exchanger.

Description

Mixed refrigerant for refrigerator using suction pipe heat exchanger

1 is a block diagram of a cooler or heat pump using a suction tube heat exchanger (SLHX) proposed in the present invention.

FIG. 2 is a comparison of the refrigerant coefficient of cold refrigerant (COP) proposed for R-22 and R-22 alternative refrigerants with and without SLHX.

3 is a comparison of the refrigerant volumetric capacity (VC) of the compressors proposed as R-22 alternative refrigerants with and without SLHX.

4 is an exemplary view comparing the freezing coefficient (COP) of cyclofurophane-containing mixed refrigerants with and without SLHX.

5 is an exemplary view comparing the freezing coefficient (COP) of the mixed refrigerant refrigerants with and without SLHX.

6 is a comparison of the compressor refrigerant volumetric capacity (VC) of cyclofuropane-containing mixed refrigerants with and without SLHX.

7 is a chart showing the temperature gradient (GTD) of the cyclofurophane-containing mixed refrigerants when using SLHX.

FIG. 8 is a graph showing the temperature gradient (GTD) of the propylene propylene-containing mixed refrigerants using SLHX.

* Explanation of symbols for main parts of the drawings

1: Evaporator

2: Suction Line Heat Exchanger

3: Condenser 4: Compressor

5: saturated evaporation band 6: condensation band

A: direction of heat flow in the condenser (from refrigerant to air)

B: Heat flow direction from the evaporator (air to refrigerant) TS1: Evaporator air inlet temperature

TS7: Evaporator air outlet temperature TS3: Condenser air outlet temperature

TS6: condenser air inlet temperature

The present invention relates to a mixed refrigerant used in a refrigerator using a suction line heat exchanger (hereinafter referred to as SLHX). More specifically, the present invention relates to a mixed refrigerant capable of replacing monochlorofluoromethane (CHClF ₂ : hereinafter referred to as R-22) in a refrigeration system using SLHX.

Conventionally, a refrigerant such as a refrigerator, an air conditioner, a heat pump, or the like is derived from methane or ethane, and is referred to as Chloro-Fluoro-Canbon (hereinafter referred to as CFC) and hydrogenated CFC (hereinafter referred to as CFC: referred to as HCFC). ) Has been used mainly, and R-22, which has a boiling point of -40.8 ° C and HCFC, has been widely used as a refrigerant for building air conditioners, large-scale refrigeration systems, and low-temperature show cases.

In recent years, the destruction of the ozone layer in the stratosphere by CFC has emerged as an important global environmental protection problem, and the use and production of chlorofluorocarbons (CFCs), which are completely halogenated and potentially ozone depleted, have been greatly restricted by the Montreal Protocol. Sooner or later, their use and production will be banned worldwide.

When the ozone depletion potential (hereinafter referred to as ODP) of trichlorofluoromethane (CCl ₃ F, R-11) is defined as 1, the ODP of R-22 is 0.05, although R-22 is completely Although not halogenated CFCs, they are widely used in air conditioners and heat pumps, and are expected to have a significant impact on human life in the future, as in CFCs, and to be prohibited from production and use under the Montreal Protocol. do. Therefore, at present, the ODP is 0.0, and the rapid development of a refrigeration fluid that can be used as a substitute for R-22 is desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mixed refrigerant having no influence on the ozone layer in the stratosphere (zero ozone destruction index: Zero) and a refrigeration system using the mixed refrigerant which can be used as a substitute for R-22.

Several types of mixed refrigerants have been proposed as alternatives to R-22, and their production or use has not been directly regulated yet, but they are based on the HCFC, which has been restricted in the Montreal Protocol. Korean Laid-Open Patent Publication No. 91-989, PCT / 91/04100 Korean Laid-Open Publication No. 93-701562) has a problem that it cannot be used as a substitute in the long term.

In addition, as a substitute for R-22, difluoromethane (hereinafter referred to as HFC-32 or R-32) and pentafluoroethane (hereinafter referred to as HFC-125 or R-125) and 1,1,1,2 An azeotrope of tetrafluoroethane (hereinafter referred to as HFC-314a or R-134a) has been proposed, namely Klea-60 and Klea-61 at ICI UK and AC-9000 at DuPont USA It was announced by name.

Klea-60 is a non-Azeotropic Mixtures of 20% HFC-32 and 40% HFC-125 and 40% HFC-134a. Klea-61 is 10% R-32 and 70% R-125 and R-134a is an azeotrope of 20% and AC-9000 is an azeotrope of 45% of HFC-32 and 25% of HFC-125 and 52% of HFC-134a. In the present invention, unless otherwise stated, the composition of the mixed refrigerants means mass ratio.

To be useful as an alternative to R-22, it must first have a vapor pressure similar to that of R-22 for use without major modifications to existing R-22 compressors, and a similar Coefficient of Performance (COP). Must have However, it is known that none of the proposed alternative refrigerants surpasses the performance of the existing R-22 in terms of COP and compressor capacity. The freezing coefficient (COP) refers to the total refrigeration effect compared to the work applied to the compressor, the larger the COP, the better the energy efficiency of the freezer.

On the other hand, the most important consideration with the COP in the design of the refrigerator is the volumetric capacity (hereinafter referred to as VC). VC is the refrigeration effect (kJ / m ³ ) per unit volume, which is proportional to the vapor pressure and represents the size of the compressor. If the replacement refrigerant is capable of freezing the existing R-22, it is very advantageous for the manufacturer to be able to build a freezer without changing the size of the compressor. However, if the refrigeration capacity of the alternative refrigerant is greater than R-22, the compressor size should be small, and the compressor should be redesigned basically because of the high pressure on the condenser side, which requires a lot of manpower and development cost.

The present invention relates to a three component mixed refrigerant consisting of any one of C ₃ hydrocarbons, such as furopropylene or cyclofurophane, and R-134a and R-125. Puropylene and cyclopurophane are not only substances having an ODP of 0.0 (Zero) and the lowest warming index, but also have the characteristics of increasing solubility and improving the coefficient of performance of refrigerated oil.

The present invention relates to a new non-azeotropic refrigerant mixture that approaches, or in most cases exceeds, the COP and compressor VC of R-22 over previously proposed and commercially available R-22 alternative mixtures. .

To develop R-22 alternative refrigerants, we first developed a simulator that simulates the performance of a domestic air conditioner (or heat pump). 1 is a block diagram of a heat pump using a suction tube heat exchanger (SLHX) used in the present invention. The heat pump modeled in the present invention also has an evaporator (1), a condenser (3), a compressor (4) basically like the heat pump generally used, and the saturated evaporation zone (5) of the refrigerant in the evaporator and the condenser, It has a condensation zone 6. If the suction tube heat exchanger 2 is installed between the evaporator 1 and the condenser 3, the temperature of the hot liquid at the end of the condenser 3 is lowered and the temperature of the cold gas at the end of the evaporator 1 is increased. . This process increases the volumetric capacity of the COP and compressor. In the drawings, a symbol A and B denotes a heat transfer flow direction between a refrigerant and air.

In this simulator, thermodynamic and heat transfer analyzes of the elements constituting the air conditioner, such as heat exchangers and compressors, were performed (see FIG. 1). Each individual product was tested and finally a complete program was developed that combined them all. One of the important factors that determine the accuracy of the developed program is the properties of the refrigerants. The simulator used Carnahan-starling-De Santis (CSD0 state equation, which is based in the US, Japan, etc.) to calculate the properties of all refrigerants.The CSD state equation was developed by the American Standards Institute and its accuracy and applicability. The design and input data for the development and execution of the simulator program use the existing real data, although the simulator can predict the performance of the real system well under the given standard conditions.

According to the results of the study by the present inventors using the simulator, the COP of each pure refrigerant showed a great difference when the SLHX was not used in the case of the pure refrigerant, but the overall COP was 5 when the SLHX was not used. It is increased by -10% and the compressor discharge temperature increases by 20 to 30 ° C (see Figure 2). Similar trends also appear in the case of VC (see Figure 3).

In the long term, the present inventors have determined that the replacement refrigerant should be HFC (Hydrofluorocarbon) or natural fluid, so that R-125, R-134a, cyclopuropane (substantially no ozone depletion potential) are present. The combination of three of the five pure refrigerants (RC-270) and furopropylene (R-1270) led to the development of alternatives to R-22.

Since RC-270 and R-1270 are combustible materials, the composition ratio of the mixed refrigerants should be minimized within the flammability range.

According to the results of the present inventors, 5-10 wt% of C ₃ hydrocarbons such as cyclopropane (RC-270) and furopropylene (R-1270), 20-50 wt% of R-125, and 45-75 wt% of R-134a are mixed refrigerants. Has no possibility of ozone depletion (ODP = 0) and shows excellent performance in existing refrigerators that do not use SLHX, as shown in Tables 1 and 2 below. Their COP and VC are very similar to R-22, and their biggest feature is that the extruder discharge temperature is as much as 20 ℃ lower than R-22.

The biggest problem with the existing R-22 was that the compressor discharge temperature was so high that the refrigeration oil broke down and the system was easily broken. Therefore, in case of the refrigerator using R-22, even if the SLHX is not used, the SLHX cannot be used because the discharge temperature of the extruder is already high.

2 to 9 show how the capacity of the COP and the compressor changes with and without SLHX for the nine pure refrigerants including R-22 and the mixed refrigerants proposed in the present invention. As shown in the figures, the use of SLHX increases the capacity of the COP and compressor of R-125, R-143a, R-134a, R-1270 by as much as 17%. On the other hand, the performance of R-22 and R-32 is almost unchanged or only increased by 2-3%. Therefore, those containing R-125, R-143a, R-134a, R-1270, and the like, which are alternative mixed refrigerants, can achieve a significant performance increase using the SLHX. It should be noted in FIG. 2 that the COPs of all refrigerants are approximately equal when SLHX is used. Therefore, if the refrigerant such as R-125 is optimized by using SLHX system, it will be able to achieve the same thermal efficiency as the existing R-22.

Tables 3 and 4 below summarize the performance of alternative mixed refrigerants when SLHX is installed. Compared to the absence of SLHX, COP increases by as much as 10%. On the other hand, the COP is also increased by 10% compared to the existing R-22 system without SLHX, and the VC is the same or slightly larger.

In addition, the discharge temperature of the compressor with SLHX is similar to the discharge temperature of the compressor of R-22 without SLHX. This fact shows that when using SLHX, the performance of the proposed refrigerants is much better than the existing R-22, and the circulation of refrigerated oil will not be a problem.

Finally, the temperature gradient of the mixed refrigerant (Gliding Temperature Difference) is called GTD. Larger GTDs mean higher azeotropes, which in turn means greater separation when there is a leak in the system. Since GTDs such as AC-9000 currently on the market are about 6.5 ° C, the GTDs of newly developed materials are also advantageous. 10 through 12 show the GTDs of the various refrigerants. As shown in this figure, the GTD of the new mixed refrigerants proposed in this time is within 3.5 ~ 6.5 ℃ except for one or two cases.

Claims (1)

In a refrigerant mixture for a refrigerator using a suction tube heat exchanger, C ₃ hydrocarbons 5 to 50 wt% of pentaflouroethane, 45 to 75 wt% of 1,1,1,2-tetrafluoroethane, or propylene or cyclopurophane An azeotropic mixed refrigerant composed at 10wt%.