What property of refrigerants is crucial for determining their efficiency?

The efficiency of refrigerants is primarily determined by their heat transfer capability. This property reflects how effectively a refrigerant can absorb and release heat during the refrigeration cycle, which is essential for maintaining desired temperatures in various applications. A refrigerant with high heat transfer efficiency can optimize the performance of the cooling system, leading to lower energy consumption and improved overall system efficiency.

Viscosity, while important for the flow characteristics of the refrigerant, does not directly impact its ability to absorb or release heat as effectively as heat transfer capability does. Color and odor are generally not related to the performance characteristics of refrigerants in a meaningful way when considering their efficiency in heat transfer.