Long Term Natural Alternatives for Halogenated Refrigerants - Hydrocarbons

Hydrofluorocarbons (HFCs) are being used presently as medium term alternatives for environmentally damaging chlorofluorocarbon refrigerants (CFCs). However, higher global warming potentials (GWP) of HFCs are still a serious environmental concern though they do not contribute to stratospheric ozone depletion. V\4ren it comes to finding refrigerants that do not deplete the ozone layer and has minimal direct global warming potential, natural fluids stand out among the potential alternatives. Among natural refrigerants hydrocarbons (HC) is one category with no ozone depleting potential and with minimal GWP potentials. Besides, compared with CFCs and HFCs, hydrocarbon show better heat transfer performance, blend well with existing lubricants and require relatively lower amounts of system charge. However, flammability of HCs raise concerns over their use in refrigeration systems. Yet, HCs are gaining increased recognition in many areas of vapour compression refrigeration as a long term refrigerant. This paper discusses heat transfer and retrofit aspects, and issues in international standards for the use of flammable HCs in refrigeration and heat pump systems.