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Approximately 70% of the global fishing fleet still uses HCFC-22 for all refrigeration applications (UNEP, 2016), mostly built before Montreal protocol requirements existed. Vessels built over the past two decades were designed for HFCs such as R-404A or R-507. Blends can usually be found for DX systems that enable a retrofit, but this can be costly due to relatively high leakage and lower overall efficiency. Flooded systems cannot be retrofitted and the option here is to refurbish with ammonia or ammonia/CO2 cascade systems. The use of HCFC-22 on cruise liners has been virtually eliminated. Some ships still operate with screw compressors and R-410A. Cruise liners operating with centrifugal chillers on HFC-134a have been successfully retrofitted to R-513A with a 1% reduction in energy efficiency. Leak rate for these systems is less than 0.5%/ annum. The storage rooms present a bigger challenge, (sometimes 50 or 60 in number on a liner). Indirect systems (where refrigerant is confined to a machine room and secondary coolant is distributed) can be retrofitted by either changing the refrigerant or changing the cooling system to R-744. Ships with direct systems are the most problematic, they have large charges (1000 kg) and are leaky due to pipe work length. HCFC-22 could be retrofitted to blends (for example R-407F) but lower efficiency could be a challenge due to temperature glide. The IMO Study 2014 provided an estimate of refrigerant leakage. Refrigerant and air conditioning gas releases from shipping contribute an additional 15 million tons (range 10.8 million to 19.1 million tons) in CO2 equivalent emissions. Inclusion of reefer container refrigerant emissions yields 13.5 million tons (low) and 21.8 million tons (high) of CO2 emissions (IMO, 2014). DNV-GL demands no higher than 10% leakage (DNV-GL, 2012). The ships’ refrigeration systems have to comply with legislative requirements of their flag state. There is consequently more pressure to retrofit ships flagged within the EU where the F-gas regulations apply (Gluckman, 2016). Reefer ships for this EU market for the carriage of fruit and frozen fish products have been retrofitted to alternate gases R-407C and R-404A respectively. This, though successful, has resulted in decreased reliability and an approximate increase in energy consumption of about 15%. Where flooded evaporators are employed using zeotropic refrigerants retrofits are considered probably not possible. Provision or storage rooms have been successfully retrofitted from HCFC-22 to R-407F, though also now there will be a need to move from R-404A systems to refrigerants of lower GWP. 6.4.4 Railways Non-flammability is of paramount concern in public transport systems operated frequently in tunnels or on bridges where fast evacuation is problematic. R-513A and R-449C are being considered as replacements for HFC-134a and R-407C going forward, but to date no such application has been reported. 6.5 Concluding remarks Since the introduction of the European F gas regulations, high GWP refrigerants have received pressure to phase down. The first refrigerant to be affected was R-404A, as a technical option had become available (R-452A). In truck and trailer, R-404A has been completely replaced by R- 452A in new equipment in Europe since 2015. Other applications using HFC-134a, have shifted in limited numbers to low GWP alternatives such as R-513A. Some refrigerated containers have been produced and are in service operating on R-744. 2018 TOC Refrigeration, A/C and Heat Pumps Assessment Report 127PDF Image | Heat Pumps Technical Options
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