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Substitutes for R22 in A/C and heat pumps changes to compressors, heat exchangers, and controls, as well as measures of tuning vibrations. There are stricter safety require- ments, e.g. affecting the quality and dimen- sions of piping and flexible tube elements (for condensing temperatures of approx. 60°C/40 bar). Another criterion is the relatively low critical temperature of 71°C. Irrespective of the design of components on the high pressure side, the condensing temperature is thus limited. R410A complies with the requirements of the EU F-Gas Regulation, which will only allow refrigerants with GWP < 2500 from 2020 onwards. However, the quantity limi- tation through the "phase-down" will also lead to significantly restricted availability. Due to the extremely high demand for R410A, a timely switch to alternatives is needed in the EU. For R410A, BITZER offers a series of semi-hermetic reciprocating compres- sors and scroll compressors. R417A/417B/422D/438A as substitutes for R22 Similar to the development of R422A (page 19), one aim of developing these blends was to provide chlorine-free refrigerants (ODP = 0) for the simple conversion of existing R22 plants. R417A was introduced to the market years ago, and is also offered under the trade name ISCEON® MO59 (Chemours). This substitute for R22 contains the blend com- ponents R125/R134a/R600 and therefore differs considerably from e.g. R407C with a correspondingly high proportion of R32. Meanwhile, a further refrigerant based on identical components, but with a higher R125 content, has been offered under the ASHRAE designation R417B. Due to its lower R134a content, its volumetric refriger- ating capacity and pressure levels are high- er than for R417A. This results in different performance parameters and a different focus within the application range. The same applies to a further blend with the same main components, but R600a as hydrocarbon additive. It is offered under trade name ISCEON® MO29 (Chemours) and listed as R422D in the ASHRAE nomenclature. Another refrigerant belonging to the catego- ry of HFC/HC blends was introduced in 2009 under the trade name ISCEON® MO99 (Chemours) – ASHRAE classifi- cation R438A. This formulation was de- signed especially for a higher critical tem- perature for applications in hot climate areas. The base components are R32, R125, R134a, R600 and R601a. Like R407C, all four substitute refrigerants are zeotropic blends with a more or less significant temperature glide. In this re- spect, the criteria described for R407C also apply here. Apart from a similar refrigeration capacity, there are nevertheless fundamental differ- ences in thermodynamic properties and in oil transport behaviour. The high proportion of R125 causes a higher mass flow with R417A/B and R422D than with R407C, a lower discharge gas temperature and a relatively high superheating enthalpy. These properties indicate that there are differences in the optimization of system components, and a heat exchanger between liquid and suction lines is of advantage. Despite the predominant proportion of HFC refrigerants, conventional lubricants can be used to some extent because of the good solubility of the hydrocarbon constituent. However, in systems with a high oil circula- tion rate and/or a large volume of liquid in the receiver, oil migration may result. In such cases, additional measures are necessary. For further information on oil return and lubricants see chapter “R422A as substitute for R22 and R502” (page 19). Due to the high global warming potential (GWP ≥ 2500), R417B and R422D will no longer be allowed for new installations in the EU from 2020. The requirements and restrictions are specified in the F-Gas Reg- ulation 517/2014. However, the "phase- down" quantity limitation will also lead to significantly restricted availability of R417A and R438A. BITZER compressors are suitable for use with R417A/417B/422D/438A. An individ- ual selection is possible upon request. R427A as a substitute for R22 This refrigerant blend was introduced some years ago under the trade name Forane® FX100 (Arkema) and is now listed in the ASHRAE nomenclature as R427A. The R22 substitute is offered for the conver- sion of existing R22 systems for which a "zero ODP" solution is requested. It is an HFC mixture with base components R32/R125/R143a/R134a. In spite of the blend composition based on pure HFC refrigerants, the manufacturer states that a simplified conversion proced- ure is possible. This is facilitated by the R143a proportion. Accordingly, when converting from R22 to R427A, all it takes is a replacement of the original oil charge with ester oil. Additional flushing sequences are not required, as proportions of up to 15% of mineral oil and/or alkyl benzene have no significant effect on oil circulation in the system. However, it must be taken into account that the highly polarized mixture of ester oil and HFC will lead to increased dissolving of decomposition products and dirt in the pipe- work. Therefore, generously dimensioned suction clean-up filters must be provided. Regarding refrigerating capacity, pressure levels, mass flow and vapor density, R427A is relatively close to R22. During retrofit, essential components such as expansion valves can remain in the system. Due to the high proportion of blend components with low adiabatic exponent, the discharge gas temperature is considerably lower than with R22, which has a positive effect at high compression ratios. It must be taken into account that this is also a zeotropic blend with a distinct tem- perature glide. Therefore the criteria de- scribed for R407C apply here as well. 22PDF Image | REFRIGERANT REPORT 21
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