- Chloro-fluoro-carbons (CFCs) – e.g., R-11, R-12
- High ozone depletion potential (ODP) and global warming potential (GWP)
- Phased out under the Montreal Protocol
- Hydro-chloro-fluoro-carbons (HCFCs) – e.g., R-22, R-123
- Lower ODP than CFCs but still harmful
- Being phased out gradually
- Hydro-fluoro- carbons (HFCs) – e.g., R-134a, R-410A, R-404A
- Zero ODP but high GWP
- Phasedown under the Kigali Amendment
- Hydro-fluoro-olefins (HFOs) – e.g., R-1234yf, R-1234ze
- Low GWP and zero ODP
- Environmentally friendly alternative to HFCs
- Natural Refrigerants
- Ammonia (NH₃) – R-717: High efficiency, zero GWP, used in industrial cooling
- Carbon Dioxide (CO₂) – R-744: Low GWP, used in commercial refrigeration
- Hydrocarbons (HCs) – e.g., R-290 (Propane), R-600a (Isobutane): Low GWP, used in household refrigerators
- Blends
- Mixtures of two or more refrigerants to achieve desired properties
- e.g., R-407C, R-508B
- Suction Line → Compressor → Discharge Line → Condenser → Liquid Line → Expansion Valve → Evaporator → Back to Suction Line
- Secondary Refrigerants
- Compressor
- Condenser
- Expansion Valve
- Evaporator
- Accumulator
- Filter-Drier
- Receiver
- Oil Separator
