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wastewater treatment plants (WWTPs) as additional TFA dischargers into the aquatic environment. TFA was neither removed by biological wastewater treatment, nor by a retention soil filter used for the treatment of combined sewer overflows. WWTP influents can even bear a TFA formation potential, when appropriate CF3-containing precursors are present. Biological degradation and ozonation batch experiments with chemicals of different classes (flurtamone, fluopyram, tembotrione, flufenacet, fluoxetine, sitagliptine and 4:2 fluorotelomer sulfonate) proved that there are yet overlooked sources and pathways of TFA, which need to be addressed in the future” (Scheurer, 2017). From leaking refrigeration applications, amounts of refrigerants are released in such a manner that degradation happens over a longer period, related to equipment lifetime. As mentioned, the lifetimes of the HFC and HFO molecules in the atmosphere are very different. Both effects will therefore result in different time horizons for the degradation of the various HFC and HFO refrigerants. Furthermore, refrigerants have been released in the past and will be in future, thus leading to increased, later aquatic ecosystem impacts (Solomon, 2016). A significant increase of TFA concentrations in rainfall on glaciers (Vollmer, 2015; Vollmer, 2018), in groundwater and in drinking water has already been measured to date, with higher than permitted TFA values measured in some groundwater samples (DVGW, 2017; NRW, 2018; GDCh, 2018). It is obvious that, lacking knowledge of the TFA formers as well as which future pollution of aquatic water systems can be expected, more research is needed concerning the impact of TFA. This particularly in light of the observed rapid and widespread uptake of HFO-1234yf in MAC applications and future use of HFOs in other applications. From the TEAP XXVII/4 Task Force report (TEAP, 2016), which gives tables for the emissions of low GWP refrigerants from servicing in the future, a value of about 60 ktonnes of HFO emissions relevant for TFA formation (from both mobile and stationary air conditioning) has been derived here for non-Article 5 countries in the year 2030. It might well concern HFO emissions relevant for TFA formation derived here at a level of about 90 ktonnes from all R/AC subsectors in Article 5 countries in the year 2030 18. 11.5.2 Reducing direct emissions The following are recommendations to reduce direct emissions from equipment and systems at the various phases of the systems’ life. These measures start with minimising emissions through design by reducing the refrigerant charge; ensuring the leak tightness of the equipment during construction, installation, use, servicing and end-of-life decommissioning; and reducing emissions throughout the five phases through proper practices and techniques. 11.5.2.1 Charge minimisation Refrigerant charge minimisation reduces the global consumption of refrigerants as well as the quantity of possible emissions during leak events and at end of life. Refrigerant charges may be reduced through the use of e.g. microchannel heat exchangers, which reduce the internal volume of the heat exchanger, and non-refrigerant secondary cooling systems. Secondary cooling systems have the added benefit of separating toxic or flammable refrigerants from occupied spaces. However, secondary systems have an effect on energy efficiency as described in chapters 4 and 9. Examples include supermarket refrigeration equipment that is designed with secondary loops and 18 Estimates are based on the emissions of HFOs from MAC applications and on the expected emissions of HFOs from stationary air conditioning (estimated here at 15% of the total) that could give rise to TFA decomposition product. 216 2018 TOC Refrigeration, A/C and Heat Pumps Assessment ReportPDF Image | Heat Pumps Technical Options
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