C022 -- Impacts of Retrofitting Lower GWP Refrigerants for Aftermarket Applications

Currently used legacy refrigerants for air conditioning and refrigeration applications such as R-410A, R-404A and R-134a have high global warming potentials (GWP). Due to this, these refrigerants have become targets for phase-down as part of global carbon emission reduction initiatives (Kigali amendment to the Montreal Protocol, EU F-Gas Regulation, etc.). Refrigerant alternatives for existing systems to be used in aftermarket applications are required to be nonflammable. Similar performance in efficiency and capacity while providing a reduction in GWP are required. Refrigerant manufacturers have developed options that attempt to fulfill these needs. However, the reduction in GWP often leads to blends that impose a gliding temperature profile in the heat exchangers besides other factors that need to be considered for drop-in situations like operating pressures, compressor discharge temperatures or material compatibility, among others. This paper evaluates the agreement between different refrigerants and the requirements for existing legacy refrigerants in air conditioning and refrigeration applications. A focus on temperature glide and inherent performance impact is evaluated and related to possible considerations for use. Refrigerant options with similar performance and operating characteristics for R-410A, R-404A and R-134a are identified with R-466A, R-448A/R-449A/R-407H and R-513A/R-456A, respectively. A close evaluation of material compatibility and detailed system modeling beyond this screening evaluation are needed to confirm viability for the specific application.