Paper No 127 – Testing of alternative refrigerants for unitary air-conditioning and heat pump applications – 14th IEA Heat Pump Conference, Chicago, USA
The unitary air-conditioning and heat pump application sector is one of the largest single consumers of refrigerant today mostly with R-410A having Global Warming Potential (GWP) of 2088 or R-32 (GWP 675). Legislative phase-down of fluorinated refrigerants is driving a search for alternatives for this application with target to lower average GWP – ideally below 300. While some alternatives such as R-454B (GWP 466) or R290 have already been identified as technically feasible, the flammability and charge size of systems may present an additional barrier to use these fluids. Use of R-744 has been considered in the past but the energy efficiency and cost of prototype systems has rendered it unattractive. A non-flammable refrigerant blend of R744, R-1132a and R-32, working name LFR3 (submitted to standards bodies for classification), GWP 142, has been developed, which in testing has demonstrated significant energy efficiency advantage over R-744. A project is now underway to assess the feasibility of using this fluid for heat pumps. The goal is to develop baseline performance on a production system designed for R-410A then to retrofit the system with new heat exchangers and compressor suitable for use with R-744 and to assess whether comparable efficiency (EER) to the R-410A may be achieved. Performance testing with R-410A, with a near drop-in low-GWP alternative (R468C, GWP 284)) and of the prototype high pressure system will also be presented