This document discusses key properties that refrigerants should possess, including having a high density, low freezing point, small volume handled per ton of refrigeration, high coefficient of performance, miscibility with oil, high conductivity, ability to be detected if leaked, pressures above atmospheric, low solubility of water, low miscibility with oil, low viscosity, small compression ratio, chemical stability, inertness, no effect on rubbers/plastics, non-flammability, no effect on oil or commodity, and non-toxicity. The ideal refrigerant maximizes these desirable properties.