Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 53 S ection 02 Fig. 2.9 Standard water cooled chiller at an IKEA store in Sweden. The system uses R-134a and is indirect for the evaporator and condenser, minimizing the charge of HFC. It operates as a heat pump in winter and as an air conditioner in summer. To minimize energy consumption, a ground “storage” with drilled holes is used for “free cooling” until the ground temperature increases in late summer when the chiller must start. Fig. 2.8 A smaller sized standard air-cooled chiller installation with R-407C installed in 2005 in Montenegro to air condition a public building. often used with screw or centrifugal chillers, where the larger volume flow required does not affect the cost as much as it does with reciprocating compressors. R-134a also has the advantage that it is suitable for use in flooded evaporators, which is not the case with R-407C that has a significant temperature glide. This temperature glide is not a significant technical challenge when used in counter flow heat exchangers with dry expansion, i.e. plate heat exchangers, as well as in many air heat exchangers that are not designed to be reversible. In systems that are designed to be used as both air conditioners and heat pumps, the challenge to use glide refrigerants becomes much more significant and R-134a or R-410A becomes a more attractive alternative. The challenge with R-410A is the significantly higher pressure, which might not be an issue for small split air-to-air systems but requires significant redesign of the pressure vessels. The designs for non-HCFC chillers are well-proven, not only in industrialised countries, but also in most Article 5 countries where have been commonly installed for several years in parallel with the old systems based on R-22 technology. The price difference is small and the HFC technology is more often developed with today’s energy efficiency requirements taken into account. Newer development of equipment with higher energy efficiency has also introduced technologies to minimize leaks and reduce charge. 2.3 Fruit Storage with hydrocarbon chillers at Nickle farm in UK Su mmary Hydrocarbarbarbon chiller with hydrocarbarbarbons used in frufrufruit storarage A hydrocarbon chiller was selected to minimize the direct global warming impact from the refrigerant. By using an indirect system, the primary refrigerant charge could be minimized (each circuit contained 5.5 kg). With chillers placed outside the building the risks are reduced. The remaining risks are associated with ensuring that a leak into the water circuit cannot be vented inside a space where it could form flammable concentrations, or that improperly trained service technicians might make mistakes that could be dangerous. These risks are not considered to be difficult to handle. The use of an indirect system and the proper design of the electrical installation on the chiller eliminated most risks associated with the use of a flammable refrigerant. The drawback was the introduction of an extra heat transfer that - if not compensated - would in theory result in a higher indirect global warming from energy consumption. By using a salt brine (potassium acetate) instead of glycols, the energy consumption for pumps and extra heat transfer was minimized. At the same time, a factory-assembled indirect system can often be more tightly optimised and more easily controlled, which can result in an improved total efficiency in spite of extra heat transfer and pumps. The fact that the refrigerant circuit was compact, factory made and easy to control was an important factor to improve reliability and decrease service costs. Background data/information given for this installation comes from Alan Colbourne, from the contractor SRS in UK (SRS). The description is based on the data received from the contractor, but as regards the selection of information and interpretation, the responsibility is with the author of this report.