AU2009264496A1 - A mixed working fluid for heat pumps - Google Patents

Description

-1 Specification A new refrigerant mixture for heat pump systems Technology outline This invention is an innovative refrigerant compound, applied in heat pump systems as a 5 substitute for CFC 12 or HCFC22. Background technology Since 1987, based on the Montreal Agreement, great efforts have been made across the world in terms of the protection of ozone layer, the elimination of the ozone-depleting substance, and the reduction of the greenhouse effect. China is also actively engaged in this world-wide 10 effort and has been working on finding a safer, more efficient and environment-friendly refrigerant substitute. Due to its high Ozone Depression Potential (ODP), CFC refrigerant is strictly restricted in the Montreal Agreement and its revised edition. Compared with CFC, HCFC is less harmful to the ozone layer in that its hydrogen atoms are replaced by halogen atoms, and that the 15 remaining hydrogen atoms can help the refrigerant to be decomposed in the stratosphere. However, HCFC was still listed as a restricted substance in Copenhagen Conference in 1992, and this has had a significant effect on refrigeration and air-conditioning industries, because HCFC22, despite its popular use at present, will be prohibited gradually. According to the Copenhagen Agreement, developed countries should completely ban the production and use 20 of CFC by 1996, and HCFC by 2020; for developing countries, the schedule is 2010 and 2030 respectively. Due to its zero ODP, HFC is considered to be the first choice among all substitutes. It includes such hydrocarbons as R23, R32, R125, R134a and R152a, which contain fluorine and exclude bromine, but HFC has the problem of chemical stability and accumulation after release, which may result in and quicken the global warming. Some 25 natural substances, like ammonia (R717), water (R718), air (R729) and carbon oxide (R744), which were substituted half a century ago by CFC, are being reconsidered to be substitutes again.

-2 Due to a lack of a pure working substance as CFC substitutes, a mixture of the working substances is a possible solution. Expected chemical properties can be achieved through adjusting the molar concentration proportion of the constituents of the mixture. In the past few years, many kinds of refrigerant mixtures were invented as substitutes of CFCI2 (also 5 named R12), CFC502 (also named R502) and HCFC22 (also named R22). However, some of them contain HCFC, which is prohibited in Montreal Agreement, and in the long-term, it is inappropriate to use these substitutes. This invention contains difluoroethane (H FCI52a, also RI52a), pentafluoroethane (HFC125, also R125) and trifluoroethane (HFCI43a, also RI43a) non-azeotropic mixture. Its advantage is that it can achieve nearly the same coefficient of 10 performance (COP) and cooling capacity through adjusting the proportion of its components of refrigerant mixtures accordingly, thus resulting in minimum modifying of the system and especially the compressor. Hence this mixture has a great developing potential. At present the most popular heat pump refrigerants are R12, R22 and some other substitute mixtures, like R407c (R32 / R125 / R134a: 23 / 25 / 52 mass fraction ), R417a (R125 / 15 R 134a / R600: 47 / 50 / 3 mass fraction ), R4Oa (R32 / R 125: 50 / 50 mass fraction). Among them, R407 and R410a are the best possible substitutes of R22, as the heat pump heater using these two mixtures can heat the water to 60 'C. It has been mentioned that some mixtures are suitable to high heat and high temperature; we do not discuss them in our invention. Also, there's some scholars use mixture of flammable RI52a and non-flammable 20 R125 as substitute of R22. In order to make sure the substitute of present refrigerant work well, this substance shall have very similar COP (coefficient of performance) of nowadays products. One of the solutions is to utilize mixture. Its advantage is that it can achieve the same coefficient of performance and VC (Volume capacity) via adjusting the proportion of its components of refrigerant mixtures 25 accordingly, thus resulting in minimum reforming of the compressor. R407C, developed by DuPont, owns a similar cooling capacity to the traditional R22, but its COP is lower, and its temperature slippage is about 7 'C. Its discharge pressure is close to that of R22, and has the advantage that it can be filled directly (except for ester lubricating oil), -3 but it has its disadvantage, i.e., it may decompose the refrigerant, resulting in leak and damage to the system. When the leak occurs, the mixture's components are likely to separate. And when the temperature slippage gets too big, the phrase change of refrigerants will lead to a constant pressure change in evaporator and condenser, resulting in the instability of 5 refrigeration system, and the decline of the efficiency of the whole system. Allied Signal Inc. developed and marketed R410a as a new substitute. R410a is a near-azeotropic mixture refrigerant, with a temperature slippage of less than 0.2 "C, and its discharge pressure is 50-60% higher than that of R22's. Its disadvantage is that it can not be filled directly, as its unit volume cooling capacity is higher, about 1.4-1.5 times that of R22's. In this case, the 10 compressor and its main parts have to be redesigned and rebuilt, which will inevitably result in an increase in cost. Besides, the heat exchanger must be optimized in order to be adapted to the lower volume flow. So despite higher energy, R410a cannot take the place of the present R22 and can only be used in new designs. According to the principle of vapor pressure selection and the basic requirements of mixture 15 substitutes, we choose R1 52a and R125 as two major mixture components. Both RI 52a and R125 have similar vapor pressure curve to R22. Compared with R22 in terms of thermophysical property, R152a's disadvantage lies in its flammability, but by adding some amount of inflammable R125, its flammability can be restrained. Although R125's global warming potential (GWP) value is high, if its proportion in the mixture is much lower than 20 R I 52a, whose GWP value is 0, the overall GWP value in the mixture can be lowered. R125 has poorer oil solubility, but RI52a has a better intermiscibility to ester lubricating oil. So if with a low proportion of R125, the mixture's oil solubility can meet the requirements. Besides, PFPE oil series and some other esters are soluble to both R152a and R125, and both of their ODP values are 0, which is vital to ozone layer protection. Moreover, both belong to 25 HFC, and have long-term advantages as a substitute. Mixtures containing R143a (HFC-143a)and one or two of R32, R134a, R125 as dual and triplet mixture are considered as the most promising substitutes of R22 in air-conditioning and heat pump system. A great deal of experiments and researches have been carried out on RI43a -4 in recent years, home and abroad. The ODP value of this invention's components, namely R125, RI43a and R152a, is zero, and its GWP is significantly lower than other refrigerants. EU, Japan and other Asian countries have made plenty of experiments, and had compounded 0-ODP and lower GWP-valued 5 refrigerants than CFC or HFC in order to achieve expected thermodynamic properties, and increased efficiency and oil solubility. Results show that propene. propane, iso-butane, DME and HFCI52a and so on can achieve this aim. Present technology usually use R125 and RI52a as one of the alternative components, neglecting the mixture of both may gain unexpected effects. 10 Recently, many countries have spent much energy developing R22 substitutes, especially those existent, safe and pure non-azeotropic refrigerants. In the refrigeration and heat cycle, the cooling or heating capacity is a factor as important as COP. As mentioned above, if the heating capacity is much lower than R22, the compressor should be redesigned and cost will increase, hence, the cooling or heating capacity should be at same level with R22. 15 This invention's components are mainly Rl52a, R125, Rl43a, and can replace R12, which is widely used in home refrigerator, and R22, which is widely used in home and business air-conditioning. Invention outline The purpose of this invention is to develop a new refrigerant mixture from two or three of 20 RI52a, R125, RI43a under the present refrigeration system. With an ODP of 0.0 and a low GWP, it will not damage ozone layer, and will reduce greenhouse effect, and is environment-friendly, nontoxic, and flammably low. It has better thermodynamic performance and thermal parameter, can be used in any heat pump of R12 and R22 refrigeration system, and have a good oil solubility to lubricant. 25 This invention's components are mainly R152a, R125, or R152a, R125, and R143a, which can be used in heat pump heat exchange system. It has excellent low temperature evaporation property and has very high COP value in -5] working condition. It can also be used as -5 substitute for R12 and R22 which are widely used in home refrigerator and vehicle air-conditioning as well as in home and business air-conditioning respectively. The formula of this invention contains: R125 and R I52a, their quality ratio is R125:l-80%, Rl52a:20-99%. 5 Dual non azeotropic mixture refrigerant components: R125: 2-50%, R152a: 50-98%. Dual non azeotropic refrigerant: R125: 5-14%, R152a: 86-95%. Dual non azeotropic refrigerant: R125: 35-65%, R152a: 35-65%. Triplet non-azeotropic mixture refrigerant components are R125, R152a and R143a, whose quality ratio is R125: 2-50%, R152a : 15-97%, R143a: 1-35%. 10 Triplet non azeotropic mixture refrigerant: R125: 2-35%, R152a : 64-97%, Rl43a: 1-10%. Triplet non azeotropic mixture refrigerant: R125: 1-80%, R152a: 20-97%, R143a: 1-5%. Triplet non azeotropic mixture refrigerant: R125: 5-15%, R152a: 85-94%, Rl43a: 1-5%. Triplet non azeotropic mixture refrigerant: R125: 35-64%, R152a: 35-65%, R143a: 1-5%. The above mixture can be used in heat pump and its extended products; the processing 15 method is to mix the components in liquid state according to the proportion. The advantages of this invention are: (1) Small temperature slippage. (2) Environment-friendly. Its ODP value is zero; its GWP value is lower than R22 and the present substitute R407C; it is environmentally protective. This is the biggest advantage of 20 this invention. (3) As the mixing proportion changes, the thermodynamic parameters change regularly. The thermodynamic parameters can be close to R12 and R22. The mixture can be used directly by the compressors for R12 and R22, without any change to the compressors. It can be filled directly and its unit volume heating capacity is the same level with that of RI12 and R22, even 25 when the amount of filling is reduced. Thermodynamic property such as unit mass heating -6 capacity is higher than R12 and R22, the discharge temperature is lower than R22, and the COP value is the same with R12 and R22. Hence it makes an ideal long-term substitute for R12 and R22. The specific method of use 5 The purpose of this invention is to develop a new refrigerant as a substitute for R12 or R22 with no damage to the ozone layer and lower greenhouse effect. In this invention uses R152a, R125 and R143a, two or three of them as components as the substitute of R12 and R22. Dual non-azeotropic Mixture of R125 and R152a's quality ratio is: R125: 1-80%, RI52a: 20-99%, after, plus RI43a compose triplet non-azeotropic mixture. 10 R 143a's quality ratio is 1-35%. The quality ratio of R 125, R 152a and R143a is R 125: 2-50%, RI52a: 35-97%, R143a: 1-35%. The preparation method is to mix physically all the components in liquid state. Table 1-1 Thermophysical property comparison between Rl52a, R125, R143a and R22 Refrigerant Molecular Molecular Standard Freezing Critical Critical critical formula weight boiling point pressure temperature specific point('C) ('C) (MPa) ("C) volume * 1 0- 3 m 3 /kg) HCFC22 CHCIF 2 84.47 -40.78 -160 4.988 96.2 1.905 HFCI52a CHF 2

CH

3 66.05 -24.4 -177 4.520 113.3 2.74 HFCI25 CF 3

CHF

2 120.02 -48.55 -102.95 3.631 66.25 1.748 HFCI43a CH 2

FCF

3 84.04 -47.2 -101 3.784 72.9 2.31 Table 1-2 Environment property comparison between R152a,R125,R143a and R22,R407c Life in GWP Flammable Refrigerant atmosphere ODP value Safe level Toxicity value range (%) (year) HCFC22 11.9 0.034 1700 inflammable Al low R407C - 0 1526 inflammable Al none HFCI52a 1.4 0 120 4.8-17.3 A2 low HFC125 29 0 3400 inflammable Al none HFCI43a 52 0 4300 7.0-10.3 A2 low 15 -ODP is based on CFC- II as 1.0.

-7 -GWP is based on CO 2 (100 years) as 1.0. Comparisons on physical properties between R125 and R152a dual refrigerator mixture Experiment A 1: physical mixture of R125 and RI52a in liquid phrase with quality ratio 5:95 Experiment A2: physical mixture of R125 and Rl52a in liquid phrase with quality ratio 10:90 5 Experiment A3: physical mixture of R125 and R152a in liquid phrase with quality ratio 14:86 Experiment A4: physical mixture of R125 and RI52a in liquid phrase with quality ratio20:80 Experiment A5: physical mixture of R125 and R152a in liquid phrase with quality ratio 28:72 Experiment A6: physical mixture of R125 and RI52a in liquid phrase with quality ratio 35:65. Experiment A7: physical mixture of R125 and RI52a in liquid phrase with quality ratio 40:60. 10 Experiment A8: physical mixture of R125 and RI52a in liquid phrase with quality ratio 50:50. Experiment A9: physical mixture of R125 and Rl52a in liquid phrase with quality ratio 65:35. Experiment AIO: physical mixture of R125 and R152a in liquid phrase with quality ratio 80:20. Properties comparison between triplet refrigerant mixture R125, R152a and R143a 15 Experiment BI: physical mixture of R125, R152a and R143a in liquid phrase with quality ratio 2:97:1 Experiment B2: physical mixture of R125, R152a and R143a in liquid phrase with quality ratio 10:89:1 Experiment B3: physical mixture of R125, R152a and R1432a in liquid phrase with quality 20 ratio 20:75:5 Experiment B4: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 35:64:1 Experiment B5: physical mixture of R125 ,R152a and R1432a in liquid phrase with quality ratio 35:60:5 -8 Experiment B6: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 40:52:8 Experiment B7: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 45:45:10 5 Experiment B8: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 41:41:18 Experiment B9: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 35:40:25 Experiment B10: physical mixture of R125, R I52a and R1432a in liquid phrase with quality 10 ratio 45:25:30 Experiment BI 1: physical mixture of R125, R152a and R1432a in liquid phrase with quality ratio 30:35:35 Experiment B12: physical mixture of R125, RI52a and R1432a in liquid phrase with quality ratio 50:15:35 15 Compare properties of the above experiment groups with that of R407C, the major substitute for R 12 and R22, and R407C the features and effects of this invention will be shown. Table 2 comparison on temperature slippage (unit: C) Seil Bubble .Bubble Serial point Dew point Temperature Serial Point Dew Point Temperature numbers temperature temperature Slippage numbers Temperature Temperature slippage Experiment -25.59 -24.50 1.09 Experiment -31.56 -26.95 4.61 Al B3 Experiment -27.10 -25.00 2.10 Experiment -34.14 -28.34 5.80 A2 B4 Experiment -28.56 -25.55 3.01 Experiment -35.18 -29.12 6.06 A3 B5 Experiment -29.96 -26.13 3.83 Experiment -37.02 -30.63 6.39 A4 B6 Experiment -32.10 -27.15 4.95 Experiment -38.51 -32.09 6.42 A5 B7 Experiment -33.87 -28.15 5.72 Experiment -39.37 -33.23 6.14 A6 B8 Experiment -35.09 -28.94 6.15 Experiment -39.65 -33.68 5.97 A7 B9 Experiment -37.41 -30.72 6.69 Experiment -42.39 -37.74 4.65 A8 BIO Experiment -40.68 -34.11 6.57 Experiment -40.71 -35.16 5.55 -9 A9 __Bll Experiment -43.81 -38.8 5.10 Experiment -44.15 -41.1 3.05 AlO B 12 Experiment -25.08 -24.34 0.74 R047C -43.63 -36.63 7.00 B1 Experiment -27.48 -25.15 2.33 B2 Note: bubble point temperature and dew point temperature is the saturation temperature under standard atmospheric pressure 101.325 kPa. Table 2 shows that the temperature slippages of all the experiments are less than that of R407C, which means that it will present no problem for commercial application. 5 Environment properties The table below compares the environment properties of the experiment groups with those of R12, R22 and R407C. The ODP is based on CFC-1 1 as reference value 1.0, and GWP is based on CO 2 as reference value 1.0. (100 years) Table 3 comparison of environment properties Refrigerant ODP GWP Refrigerant ODP GWP Experiment Al 0 289 Experiment B4 0 1310 Experiment A2 0 448 Experiment B5 0 1482 Experiment A3 0 612 Experiment B6 0 1766 Experiment A4 0 776 Experiment B7 0 2014 Experiment A5 0 1038 Experiment B8 0 2268 Experiment A6 0 1268 Experiment B9 0 2313 Experiment A7 0 1432 Experiment B10 0 2850 Experiment A8 0 1760 Experiment B11 0 2567 Experiment A9 0 2252 Experiment B12 0 3385 Experiment A 10 0 2748 R12 0.82 8100 Experiment B1 0 227 R22 0.034 1700 Experiment B2 0 490 R407C 0 1526 Experiment B3 0 985 10 Table 3 shows that the experiments' ODP is 0.0, better than R12 and R22, which means that it's harmless to the ozone layer. It also shows that the GWP value of the above experiments Al-A5 is less than that of R22 and R407C, which means that it is superior in terms of the protection of the ozone layer and the decrease of greenhouse effect.

-10 Performance parameters of heat pump cycle This invention gained different thermodynamic parameters of different proportioning mixtures, with the most-used physical property calculation software, and the cycle performances were calculated and compared when the average evaporation temperature is 5'C 5 as show in Table 4-1. Table 4-1 Cycle performance of R12 and R22 and their substitutes (evaporation temperature 5'C) Condensatio Evaporatio Unit mass Specific Serial numbers n pressure n pressure ratio heating capacity wor o COP (MPa) (MPa) kJ/kg resso Experiment A 1 1.2218 0.3212 3.8039 289.54 62.07 4.67 Experiment A2 1.2676 0.3281 3.8634 280.83 61.18 4.59 Experiment A3 1.3149 0.3357 3.9169 272.04 60.19 4.52 Experiment A4 1.3636 0.3440 3.9639 263.10 59.06 4.46 Experiment A5 1.4449 0.3591 4.0236 248.53 56.97 4.36 Experiment A6 1.5199 0.3744 4.0596 235.56 54.93 4.29 Experiment A7 1.5759 0.3869 4.0731 226.15 53.32 4.24 Experiment A8 1.6948 0.4166 4.0682 206.97 49.76 4.16 Experiment 1.8945 0.4781 3.9626 177.24 43.53 4.07 A9 Experiment 2.1301 0.5726 3.7201 146.27 36.24 4.04 A10 Experiment B1 1.2060 0.3190 3.7806 293.52 62.54 4.69 Experiment B2 1.2788 0.3301 3.8740 279.65 61.15 4.57 Experiment B3 1.4201 0.3557 3.9924 256.71 58.42 4.39 Experiment B4 1.5316 0.3773 4.0594 234.24 54.75 4.28 Experiment B5 1.5784 0.3895 4.0524 228.80 53.86 4.25 Experiment B6 1.6710 0.4142 4.0343 215.10 51.35 4.19 Experiment B7 1.7552 0.4393 3.9954 202.51 48.79 4.15 Experiment B8 1.8036 0.4589 3.9303 198.88 47.96 4.15 Experiment B9 1.8155 0.4663 3.8934 200.56 48.24 4.16 Experiment 2.0064 0.5431 3.6943 173.09 41.82 4.14 BIO Experiment 1.8760 0.4926 3.8084 196.33 47.08 4.17 BI I Experiment 2.1451 0.6102 3.5154 155.46 37.47 4.15 A12 R22 1.9427 0.5841 3.3260 197.24 42.89 4.60 R12 1.2166 0.3620 3.3608 144.7 30.89 4.68 R407C 2.2160 0.3853 5.7514 217.06 64.86 3.35 In order to compare the properties of heat pump cycles in winter, we calculated the properties in -5*C condition, as is shown in Table 4-2.

-11 Table 4-2 Cycle performance of R12 and R22 and their substitutes (evaporation temperature -5'C) Serial numbers Condensation Evaporation Pressure Unit mass Specific work COP pressure pressure ratio heating of compressor (MPa) MPa) capacity(kJ/kg) (kJ/kg) Experiment A 1 1.0775 0.2243 4.8038 302.87 73.07 4.15 Experiment A2 1.1192 0.2293 4.8809 293.91 71.96 4.08 Experiment A3 1.1623 0.2347 4.9523 284.81 70.71 4.03 Experiment A4 1.2066 0.2406 5.0150 275.62 69.36 3.97 Experiment A5 1.2806 0.2513 5.0959 260.59 66.86 3.90 Experiment A6 1.3487 0.2623 5.1418 247.23 64.46 3.84 Experiment A7 1.3997 0.2713 5.1581 237.50 62.56 3.80 Experiment A8 1.5070 0.2927 5.1486 217.70 58.40 3.73 Experiment A9 1.6871 0.3378 4.9944 193.02 52.63 3.67 Experiment A 10 1.8986 0.4082 4.6512 155.11 42.83 3.62 Experiment B1 1.0630 0.2228 4.7711 307.00 73.65 4.17 Experiment B2 1.1294 0.2307 4.8955 292.71 71.92 4.07 Experiment B3 1.258 I 0.2490 5.0526 269.12 68.58 3.92 Experiment B4 1.3593 0.2644 5.1411 245.88 64.24 3.83 Experiment B5 1.4017 0.2733 5.1288 240.36 63.24 3.80 Experiment B6 1.4855 0.2912 5.1013 226.25 60.29 3.75 Experiment B7 1.5615 0.3095 5.0452 213.27 57.33 3.72 Experiment B8 1.6051 0.3241 4.9825 209.64 56.39 3.72 Experiment B9 1.6159 0.3297 4.9011 211.57 56.82 3.72 Experiment B 10 1.7873 0.3873 4.6148 183.26 49.42 3.71 Experiment B 11 1.6705 0.3495 4.7797 206.91 55.54 3.73 Experiment B12 1.9115 0.4386 4.3582 165.09 44.36 3.72 R22 1.7292 0.4218 4.0996 207.87 50.73 4.10 R12 1.0821 0.2606 4.1523 150.68 36.25 4.16 R407C 1.9723 0.3853 5.1189 208.61 57.25 3.64 Table 4 shows that the above experiments A I-A7, with the increasing of R125, the COP of the mixture is reducing and the temperature slippage is increasing. In the above experiments AI-A3, the condensing pressure, evaporating pressure, and pressure 5 ratio are close to those of R12, the range is within the sustainable scope. Besides, their unit volume heating capacity is at a comparable level with R12, which means that it can be used directly in R12 compressors, without redesigning the compressors, and can be filled directly as well. The above experiments A7-A9, the condensing pressure, evaporating pressure, and pressure ratio are close to those of R12, the range is within the sustainable scope, but unit 10 volume heating capacity is less than R22. All the COP of above experiments is bigger than R407C, the substitute of R22, at same level with R12, R22. In the above experiment groupsBl-B4, the condensation pressure, the evaporation pressure and the pressure ratio are close to those of R12, within the permissible limits, and that it can - 12 be filled directly as substitute for R12.

Claims (10)

1. Dual nonazeotropic refrigerant mixture, composed of R125 and R152a, their quality ratio is R125:1-80%, R152a:20-99%.

2. According to claim 1,the quality ratio is: R125: 2-50%, R152a: 50-98%. 5

3. According to claim 1,the quality ratio is: R125: 5-14%, Rl52a: 86-95%.

4. According to claim 1,the quality ratio is: R125: 35-65%, R152a: 35-65%.

5. Triplet dual nonazeotropic refrigerant mixture, features in quality ratio, composed ofR125: 2-50%, R152a: 15-97%, R143a: 1-35%.

6. According to claim 5, the quality ratio is: R125: 2-35%, R152a: 64-97%; R143a: 10 1-10%.

7. According to claim 5, the quality ratio is: R125: 1-80%, R152a: 20-97%, R143a: 1-5%.

8. According to claim 5, the quality ratio is: R125: 5-15%, RI52a: 85-94%, R143a: 1-5%. 15

9. According to claim 5, the quality ratio is: R125: 35-64%, R152a: 35-65%, R143a: 1-5%

10. Any of the mixture from claim 1-9 is proper to use in heat pump and its augmented products.