KR100315252B1 - Alternative Refrigerants for CarAircone/Household Refrigerator - Google Patents

Abstract

The present invention is a mixed refrigerant that can replace CFC12, 1,1,1,2-tetrafluoroethane less than 4.99 to 89.73 Weight%, 1,1-difluoroethane 5 to less than 74.95 Weight, Trifluoroiodo methane 5 Near azeotropic mixed refrigerant consisting of less than -69.60 Weigh and additives 0.07-0.5 Weight, less than 5-89.65 Weigh of 1,1,1,2-tetrafluoroethane, less than 5-89.04 Weight of Dimethylether, less than 5-69.7 Weight of Trifluoroiodomethane It relates to a near azeotropic mixed refrigerant composed of 0.05 to 0.4 weight and to a near azeotropic mixed refrigerant composed of less than 5 to 94.93 weight of dimethylether, less than 5 to 94.05 weight of trifluoroiodomethane, and 0.05 to 0.31 weight of additive. The mixed refrigerant of the present invention has no possibility of ozone depletion, and is an alternative refrigerant of CFC12, which has been widely used in conventional refrigerators and air conditioners for automobiles, and shows an excellent effect on the freezing performance coefficient and the freezing volume of the compressor, without changing the compressor or lubricant. It can effectively replace CFC12.

Description

Alternative Refrigerants for CarAircone / Household Refrigerator}

The present invention relates to an alternative refrigerant composed of a plurality of hydrofluorocarbons, dimethyl ether, carbon fluoride iodide and the like. More specifically, the present invention relates to a mixed refrigerant capable of replacing dichlorodifluoromethane (CCI ₂ F ₂ : hereinafter referred to as CFC12) that has been applied as a refrigerant in automobile air conditioners and household refrigerators.

Until now, hydrochlorinated fluorocarbons (Chloro-Fluoro-Carbon: hereinafter referred to as CFC) and hydrogen derived from methane or ethane as refrigerants such as refrigerators, air conditioners and heat pumps (Hydro-Chloro) Fluoro-Carbon (hereinafter referred to as HCFC) has been mainly used, and CFC12, which has a boiling point of -29.79 ° C and a molecular mass of 120.93 kg / kmol, is used most frequently in automobile air conditioners and household refrigerators.

Recently, the destruction of the ozone layer in the stratosphere by CFCs has emerged as an important global environmental protection problem, and the use and production of CFCs, which are completely halogenated and have a high possibility of stratospheric ozone depletion, are greatly restricted by the Montreal Protocol. CFC12 is the one with the largest ozone depletion index (ODP, OFC of CFC11 as 1.0), which is the largest among CFC series refrigerants (ODP = 0.9 of CFC12) .The production and use of CFC12 is prohibited according to the Montreal Protocol. . As a result, most countries are currently using alternative refrigerants with low ODPs, such as HCFCs, which are close to 0.0 or ODPs, such as HFCs, and are investing heavily in research and development to develop them.

To be useful as an alternative to CFC12, it must first have a similar vapor pressure as CFC12 and have a similar Coefficient of Performance (COP) so that it can be applied without major modifications to existing CFC12 compressors. Here, the COP means the total refrigeration effect compared to the work applied to the compressor, and the greater the COP, the better the energy efficiency of the freezer.

On the other hand, the most important factor along with COP in refrigeration / air conditioner design is volumetric capacity (VC). VC is a variable representing the freezing effect per unit volume, the unit is kJ / m ³ . VC is a factor that indicates the size of the compressor, which is proportional to the vapor pressure. If the alternative refrigerant can achieve the refrigeration capacity of the existing CFC12, it can be very advantageous to manufacture a refrigeration / air conditioner without changing the size of the compressor from the standpoint of the manufacturer or consumer.

The results of the research so far indicate that in the case of replacing CFC12 with the currently known pure refrigerant, the volumetric capacity (VC) of the replacement pure refrigerant is different from that of CFC12, and thus, the compressor must be replaced and a coefficient of performance (COP) similar to that of CFC12 is required. It turns out that it is difficult to bet. One useful way to solve this problem is to use mixed refrigerants. The characteristic of the mixed refrigerant is that the composition can be well blended to give the same vapor pressure as the existing refrigerant, and at the same time, it is not necessary to change the compressor because it uses the same lubricating oil. Because of this, several mixed refrigerants have been proposed in the last few years as a replacement for CFC12.

In DuPont, USA, MP-39 (53% CFC22 / 34% CFC124 /

13% CFC152a), MP-66 (61% CFC22 / 28% CFC124 / 11% CFC152a), MP-52 (33% CFC22 / 52% CFC124 /

Three-way mixed refrigerants such as 15% CFC152a) have been developed and marketed now.Monroe Air Tech has developed a three-way mixed refrigerant called GHG-X3 (65% CFC22 / 4% R600a / 31% CFC142b) composed of HCFC and hydrocarbons. IGC and Pennzoil have also developed and marketed a three-way mixed refrigerant called FRIGC (39% CFC124 / 59% CFC134a / 2% R600) consisting of HCFC, HFC and hydrocarbons. In addition, various mixed refrigerants are applied to a specific cooling / air conditioner.

The object of the present invention is that since the ODP is 0.0, it does not affect the ozone layer of the stratosphere at all, and at the same time, it can be usefully used as a substitute for CFC12 in refrigeration / air conditioners such as automobile air conditioners and household refrigerators without changing compressors or lubricants. To provide a mixed refrigerant.

The present invention relates to binary and tertiary mixed refrigerants composed of HFC134a, HFC152a, RE170 (Dimethylether), CF ₃ I (Trifluoroiodomethane) and the like. More specifically, the present invention is a near azeotropic mixture that has more access to COP and VC of CFC12 or better than most of them, compared to already commercially available CFC12 alternative mixture media, and the environmental index is so good that it rarely causes environmental problems. It relates to a near-azeotropic refrigerant mixture.

In order to develop CFC12 alternative refrigerants, we first created a program that simulates the performance of a refrigeration / air conditioner. 1 is a block diagram of a general refrigeration / air conditioner used in the present invention, and is composed of an evaporator, a condenser, a compressor, an expansion valve, and the like. The program first carried out thermodynamic and heat transfer analysis of the components that make up the refrigeration / air conditioner, such as heat exchangers and compressors, and finally developed a full program that combined them all. One of the important factors that determine the accuracy of this program is the properties of the refrigerants. In this program, the properties of all refrigerants were calculated using the Carnahan-Starling-De Santis (CSD) state equation, which is standard in the United States and Japan. The CSD state equation was developed by the National Institute of Standards and Technology and has already been proven in accuracy and applicability through research programs by manufacturers and research schools. The design and input data for the development and implementation of the refrigeration / air conditioner program we created used actual data as existing as possible.

The inventors have determined that the ozone depletion index of CFC12 replacement refrigerant for refrigeration / air conditioner should be very low, HFC134a and HFC152a which do not contain any chlorine and RE170 which is a natural refrigerant, and recently developed do not cause ozone layer destruction and the global warming index. We have developed a mixed refrigerant that combines CF ₃ I, which is found to be very low, to effectively replace CFC12. Table 1 shows the environmental indices of some pure refrigerants, where ODP is relative to CFC11's ODP of 1.0 and GWP to carbon dioxide's GWP of 1.0.

Environmental Index of Some Pure Refrigerants Refrigerant ODP (Ozone Destruction Index) Global Warming Index (GWP) CFC12 0.9 8,500 HFC134a 0.0 1,300 HFC152a 0.0 450 CF ₃ I 0.0 5 or less RE170 0.0 3 or less Propane 0.0 3 or less

Table 2 shows the performance indices of CFC12 and CFC12 alternative mixed refrigerants proposed by the present inventors based on a summary of the results calculated using the computational analysis cycle program under the condition of the vehicle air conditioner. As can be seen from Table 2, all of the refrigerants of Examples 1 to 3 were found to be similar or greater in terms of freezing capacity and coefficient of performance than in conventional CFC12 in almost all compositions. In addition, the temperature gradient is up to 1.26 ℃ and most of them are close to 0.0 ℃, so they are all azeotropic. On the other hand, the ozone depletion index (ODP) is all 0.0, so it can be said to be very excellent in terms of preservation of the ozone layer. Finally, the pressure ratio of these refrigerants is similar to that of CFC12, which shows no problem for the compressor.

To demonstrate the above theoretical results, a refrigeration system was actually built and tested under the condition of a car air conditioner. Figure 2 shows a schematic diagram of an air conditioner for measuring the performance of a CFC12 alternative mixed refrigerant. In this experiment, the heat exchanger used as the evaporator and the condenser was made by connecting two copper tubes of 19.01mm inner diameter, 25.4mm outer diameter and 740mm length in series. As a compressor of this experimental apparatus, an open-type reciprocating compressor, which is currently used as a compressor for a transportation refrigeration truck, was connected to an electric motor and an inverter. Creating a system in this way has the advantage that the speed can be adjusted using an inverter like a real car air conditioner. Manual expansion valves were used to control the amount and pressure of refrigerant entering the evaporator.

In order to measure the temperature of the refrigerant and water in the evaporator and condenser, more than 20 T-type thermocouples were inserted into the refrigerant and water flow pipes at the connection of the heat exchanger, respectively. All thermocouples were precision thermometers of 0.01 ° C prior to use. Corrected. In order to determine the capacity of the evaporator, it is necessary to accurately measure the flow rate and temperature difference of the secondary fluid flowing through the evaporator. In order to accurately measure the temperature difference on the secondary fluid side, six thermocouples were connected to make a thermopile, which was also calibrated with a precision thermometer and inserted into the water inlet and outlet to measure the temperature difference directly. The suction and discharge temperatures of the compressor were also measured, and the changes in the stability of the compressor and the mixing ratio of the refrigerant were also examined.

Theoretical Performance Comparison of CFC12 and Alternative Mixed Refrigerants Refrigerant Furtherance(%) COP VC (kJ / m ³ ) GTD (℃) ODP PR COP difference (%) VC car (%) R134a R152a RE170 CF3I additive CFC12 2.42 2287 0.00 0.90 3.11 0.0 0.0 Embodiment 1 of the present invention 5 20 75 2.46 2439 0.52 0.00 3.12 1.7 6.6 5 69.87 25 0.13 2.48 2359 1.14 0.00 3.30 2.5 3.2 5 88.93 6 0.07 2.45 2231 0.34 0.00 3.41 1.2 -2.4 10 64.85 25 0.15 2.48 2369 1.18 0.00 3.30 2.4 3.6 10 74.92 15 0.08 2.44 2296 0.89 0.00 3.39 0.7 0.4 15 15 69.54 0.47 2.46 2510 0.44 0.00 3.11 1.7 9.8 15 59.8 25 0.20 2.48 2379 1.23 0.00 3.30 2.4 4.0 20 44.68 35 0.32 2.48 2453 1.26 0.00 3.24 2.4 7.3 25 25 49.5 0.50 2.46 2544 0.63 0.00 3.17 1.7 11.2 34.8 34.8 30 0.40 2.47 2471 1.42 0.00 3.25 2.1 8.0 40 54 5.92 0.08 2.45 2270 0.48 0.00 3.41 1.2 -0.7 89.73 5 5 0.27 2.43 2412 0.67 0.00 3.37 0.4 5.5 Embodiment 2 of the present invention 5 5.9 89.05 0.05 2.48 2161 2.65 0.00 3.14 2.5 -5.5 5 89.04 5.9 0.06 2.47 2199 0.20 0.00 3.34 2.1 -3.8 11.8 49.01 40 0.09 2.48 2330 0.61 0.00 3.24 2.5 1.9 15 15 69.7 0.30 2.48 2452 0.85 0.00 3.12 2.5 7.2 15 54.9 30 0.10 2.48 2337 0.68 0.00 3.25 2.6 2.2 15.34 54.9 29.6 0.16 2.49 2375 0.75 0.00 3.23 2.9 3.9 24.92 25 49.6 0.48 2.48 2506 0.61 0.00 3.15 2.5 9.6 24.78 50 25 0.22 2.49 2390 0.76 0.00 3.24 2.9 4.5 30 39.7 30 0.30 2.49 2450 0.77 0.00 3.21 2.9 7.2 34.56 35 30 0.44 2.49 2488 0.73 0.00 3.20 2.9 8.8 34.73 50 15 0.27 2.49 2409 0.69 0.00 3.25 2.9 5.3 39.66 40 20 0.34 2.49 2466 0.69 0.00 3.23 2.9 7.8 39.79 55 5.9 0.31 2.49 2454 0.54 0.00 3.20 2.9 7.3 89.65 5 5 0.35 2.38 2467 0.54 0.00 3.39 -1.7 7.9

Refrigerant Furtherance(%) COP VC (kJ / m ³ ) GTD (℃) ODP PR COP difference (%) VC car (%) R134a R152a RE170 CF3I additive Embodiment 3 of the present invention 5 94.95 0.05 2.42 1962 1.36 0.00 3.24 0.0 -14.2 15 84.7 0.3 2.45 2182 0.49 0.00 3.18 1.2 4.6 20 79.77 0.23 2.45 2228 0.15 0.00 3.19 1.2 2.6 25 74.82 0.18 2.45 2254 0.02 0.00 3.20 1.2 1.4 30 69.87 0.13 2.45 2267 0.01 0.00 3.21 1.2 0.8 35 64.9 0.12 2.45 2273 0.06 0.00 3.22 1.2 0.6 49.85 49.15 0.10 2.46 2264 0.26 0.00 3.25 1.7 -1.0 59.8 40 0.20 2.47 2248 0.32 0.00 3.27 2.0 1.7 64.78 34 0.22 2.47 2238 0.32 0.00 3.29 2.0 2.2 69.77 30 0.23 2.47 2227 0.31 0.00 3.30 2.0 2.6 74.75 25 0.25 2.47 2216 0.28 0.00 3.31 2.0 3.1 79.73 20 0.27 2.47 2205 0.24 0.00 3.32 2.0 3.6 94.93 5 0.07 2.46 2172 0.07 0.00 3.35 1.7 -5.0

○ COP: Coefficient of performance =

○ VC: Volumetric capacity of the compressor

○ GTD: When the temperature is below 9 ℃

No problem when applied to the stem)

ODP: Ozone depletion index (lower is better to avoid ozone depletion)

○ PR: ratio of compressor discharge pressure and suction pressure (similar to standard refrigerant)

○ COP difference: difference in freezing performance coefficient compared to CFC12

○ VC difference: difference between compressor refrigeration volume and CFC12

On the other hand, a capillary tube was inserted into the inlet and outlet of the evaporator and condenser to make a pressure measurement port, and the pressure on the refrigerant side was measured using a precision pressure transducer having a degree of less than 0.1%. The required power of the compressor was measured using a precision torque meter with less than 0.2% accuracy. To accurately determine the air conditioner capacity, the mass flow rate of the secondary fluid on the evaporator must be accurately measured and the energy balance on the refrigerant side and the secondary fluid side. To see if this is true, the flow rate on the refrigerant side must be measured. For this purpose, this study uses the principle of Coriolis force and uses a mass flowmeter with a high accuracy of 0.2% without being influenced by the viscosity or density of the fluid, and the refrigerant circulating inside the system and the flow rate of the secondary fluid in the evaporator. The flow rate of was measured accurately. Finally, data such as temperature, pressure, and flow rate were collected at 15-30 second intervals by connecting the PC and HP3852 Data Logger.The collected data is stored on the PC's hard disk to use the program for data interpretation later. To be analyzed.

Table 3 summarizes the experimental results. When the experiment was conducted, only the refrigerant having a representative composition was taken from each theoretically calculated refrigerant group, and its performance was measured. As can be seen from Table 3, the refrigerants of Examples 1, 2 and 3 of the present invention have been shown to be better than CFC12 in terms of both performance coefficient and capacity, and the compressor discharge temperature is similar to or slightly higher than that of CFC12. It is not expected to affect the performance of the system at all. Particularly, the addition of RE170 and CF ₃ I resulted in greater compatibility with refrigeration lubricating oil, which significantly increased performance coefficient and capacity.

Experimental Performance Comparison of CFC12 and Its Alternative Mixed Refrigerants Refrigerant Furtherance(%) COP Capacity (W) Discharge temperature (℃) COP Difference (%) Capacity difference (%) R134a R152a RE170 CF3I CFC12 2.15 3622 81.5 0.0 0.0 Inventive Example 1 10 75 15 2.51 4344 90.4 16.5 19.9 Inventive Example 2 30 40 30 2.59 3899 79.9 20.4 7.7 Inventive Example 3 70 30 2.76 4339 83.1 28.3 19.8

○ Capacity: Evaporator capacity available when using the same compressor

○ Discharge temperature: Compressor discharge temperature (within ± 10 ℃ compared to standard refrigerant)

No problem.)

Explanation of symbols for the main parts of the construction drawing of FIG. 1)

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

Qe: Heat flow direction in the evaporator (air → refrigerant)

TS1: Evaporator air inlet temperature, TS7: Evaporator air outlet temperature

TS3: condenser air outlet temperature, TS6: condenser air inlet temperature

Fig. 1 is a general diagram of a refrigeration / air conditioner

2.Schematic diagram of a refrigeration / air conditioner experiment apparatus

CH ₃ CH ₃ CH ₃ ｜ ｜ ｜ H ₃ C ― Si ― O ― Si ― O ― Si ― CH ₃ ｜ ｜ ｜ CH ₃ CH ₃ n CH ₃

Chemical Formula of Silicon Additives

Although several types of mixed refrigerants have been proposed to replace CFC-12 over the past few years, they all suffer from poor performance, environmental problems and short-term use, making it difficult to be the ultimate replacement. However, as proposed in the present invention, the alternative refrigerant composed of fluorocarbon, dimethyl ether, and fluoride iodide does not cause ozone decay at all, and has no toxicity, and in particular, the thermal efficiency is 15% higher than that of a conventional refrigerant, such as an automobile air conditioner and a refrigerator. It has the advantage that it can greatly reduce the global warming problem that occurs inevitably. In the future, regulations on carbon dioxide emissions will be initiated by the Kyoto Protocol. On the other hand, even with this advantage, if the price of the refrigerant is too expensive or if the existing parts and lubricants need to be replaced, it is very difficult for the manufacturer to apply it to the product. However, the refrigerants of the present invention are similar in price to conventional HFC134a refrigerants or other mixed refrigerants, and can also use existing automotive air conditioner parts and lubricants without affecting production costs, thus making automobile manufacturers competitive. have.

Claims (2)

8-13% by weight of 1,1,1,2-tetrafluoroethane, 72-78 weight% of 1,1-difluoroethane, and 13-18 weight% of trifluoroiodomethane in a mixed refrigerant for refrigeration / air conditioner containing CF3I Azeotropic mixed refrigerant consisting of A mixed azeotropic refrigerant comprising 28 to 32 weight% of 1,1,1,2-tetrafluoroethane, 38 to 42 weight% of dimethylether, and 28 to 32 weight% of trifluoroiodomethane in CF3I containing refrigerants.