Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 67 S ection 02 2.7.3 MarMarket situation for COCO2 as a refrigerarant in supermarkets Th ere are severaral suppliers of factory-built CO2 systems and a significant number of supermarkets have installed them on many different markets in industrialized countries. The challenges with CO2 increases at high ambient and the high pressure requires that staff of installation and service companies are trained to work with these systems. The currently higher investment has also been a negative factor when it comes to the introduction in Article 5 countries. The product development is continuing and several different system designs are in production, including both supercritical and sub critical systems in cascade with other refrigerants. In cascade systems, the CO2 is used sub critical in combination with any type of refrigerant such as hydrocarbons, ammonia or HFCs in the high stage. By using the CO2 as a low cost and environmentally benign medium to distribute the cooling in the store, the charge and leakage risk of the media in the high temperature stage can be minimized. This reduces the potential leakage problems associated with using hydrocarbons, ammonia, and HFCs. As the charge of ammonia or hydrocarbon would be low, the risks are easier to manage and with use of CO2 as media to transport the cooling the systems can be placed in safe areas where the risks of flammability or toxicity are relatively easy to handle and servicing is easy to perform. By combining the CO2 designs with improved control systems and effective heat recovery, good energy efficiency have been reported. Nevertheless, there is a debate on the cost aspects and what system will give the best efficiency, in particular in hot climates. In any case, development gradual improvements can be expected as well as decreased prices as the technology matures. Some argue that if an additional investment is made, there could be other improvements that would change the TEWI and/or LCC analyses between the different design options, so the discussion on CO2 competiveness in the supermarket and other sectors is ongoing. It can be expected that this technology will mature and stabilise during the next few years. With a standardisation and increasing volumes the prices should also decrease. 2.8 Retrofit of R-22 supermarket in Romania to R-404A Su mmary Retrofit of R-22 systems in supermarket to R-404A The supermarket had two central systems for cooling. One system was medium temperature (chilled food at approximately 4°C) and one low temperature (freezing at approximately -20°C). The transition to R-404A was chosen as the oil change and use with a “standard” refrigerant with a soluble oil was considered a better option than using a drop-in replacement with the existing oil. The uncertainty of the oil transport and requirement to secure future service availability with a service blend not widely used was considered more important than the cost to replace the oil. The oil change was done first once when the system was decommissioned by draining at all available taps/valves and then with a follow up the oil change. The system was found to work well on R-404A after the retrofit. In this case, several seals and components were replaced but no pressure vessels had to be changed on this installation.