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The following table (Tab. 5) lists a range of currently available refrigerants or refriger- ants declared as development products. Due to the large number of different ver- sions and the potential changes in develop- ment products, the tables on pages 42/43 (Tab. 7/8) only list data of alternatives for R134a, R404A/R507A and R410A which are already commercially available. For testing the "Low GWP" refrigerants, AHRI (USA) has initiated the "Alternative Refrigerants Evaluation Program (AREP)". It has investigated and evaluated several of the products mentioned in Tab. 5 as well as halogen-free refrigerants. Further development projects with "Low GWP" refrigerants For specific applications, Chemours has developed a non-flammable (A1) R410A alternative, which is marketed in selected countries and regions under the trade name OpteonTM XP41 – listed by ASHRAE as R463A. It is a mixture of R32, R125, R1234yf, R134a and CO2 with a GWP of 1494. Despite the high proportion of R32 and R1234yf, flammability is suppressed by mixing with R125, R134a and CO2. Regarding thermodynamics, the differences to R410A are comparatively small. The addition of CO2, however, leads to a distinct temperature glide, which may cause certain limitations for the application and places particular demand on the design of the heat exchangers. All mixture components and their properties are well known, which means there are no additional particularities regarding material compatibility in comparison to the already known R410A alternatives. The supply of compressors for laboratory or field tests requires an individual review of the specific application and a special agreement. Some time ago, Honeywell has unveiled the new development of a non-flammable (A1) R410A alternative under the trade name Solstice® N-41 – listed by ASHRAE as R466A. A final assessment of these mixtures is therefore currently not possible. HFOs and HFO/HFC blends R466A is a mixture of R32, R125 and R13I1 (CF3I − trifluoroiodomethane), an iodine-methane derivative not previously used in refrigeration. CF3I is not flam- mable, as is R125, which means that the refrigerant is not flammable (A1), even with the relatively high proportion of R32 (A2L). Despite the noticeable proportion of R125 with a GWP of 3500, the total GWP is 733 (AR4) and therefore in the range of R32 and R452B, which are however classified as A2L. From a thermodynamic point of view, the differences between R410A and R466A are relatively small. Volumetric refrigerating capacity, pressure levels and discharge temperature are slightly higher, the refriger- ant mass flow deviates slightly more (about 15 to 20% higher). The temperature glide is also very low. Hence, R466A appears to be a promising substitute for R410A. However, due to the CF3I share, there are still uncertainties regarding long-term chemical stability and material compatibility under the special requirements of the refrigeration cycle. Further investigation is required, so a final assessment of R466A is currently not pos- sible. In any case, as matters stand, this refrigerant cannot be used in state-of-the- art systems (retrofit). The supply of com- pressors for laboratory tests requires an individual review of the specific application as well as a special agreement. AGC Chemicals propagates R1123 (CF2=CHF) mixed with R32, partially with addition of R134yf, as an alternative to R410A and pure R32. It is an HCFO with very low ozone depletion potential (ODP). R1123 has a significantly higher volumetric refrigeration capacity than R1234yf or R1234ze(E) and is advantageous in this respect. However, the pressure level is even higher than of R32 and the critical temperature is only about 59°C. Apart from that, there are unanswered questions about the chemical long-term stability under the special requirements of the refrigeration cycle. According to the safety data sheet, this substance is also subject to very strin- gent safety requirements. Comment from a compressor manufactur- er’s point of view: It should be an aim to limit the product variety currently becoming apparent and to reduce the future supply to a few "stan- dard refrigerants". It will not be possible for component and equipment manufacturers nor for installers and service companies to deal in practice with a larger range of alternatives. 26 BITZER was involved early on in various projects with HFO/HFC blends and was thus able to gain important insight into the use of these refrigerants. Semi-her- metic reciprocating compressors of the ECOLINE series as well as CS. and HS. screw compressors can already be used with this new generation of refrigerants. Several of them have already been qualified and approved, the respective performance data is available on the BITZER SOFTWARE. Scroll compressors of the ORBIT GSD6..VL and GSD8..VL series are approved and released for the use of the R32/HFO mixtures R452B and R454B. Further information on the application of HFOs and HFO/HFC blends see bro- chure A-510, section 6.PDF Image | REFRIGERANT REPORT 21
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