Final answer:
Blended refrigerants in a refrigeration system cause a temperature glide during phase changes due to different evaporation and condensation rates of the components, which affects both charging and system servicing. The COP of a system is higher when the temperature difference within the cycle is smaller, which is why heat pumps are less efficient in colder climates.
Step-by-step explanation:
When a system is charged with a blended refrigerant, the behavior during the refrigeration cycle can differ from that of pure refrigerants. Blended refrigerants are mixtures of two or more refrigerants with different properties. These blends are designed to optimize the performance of the refrigeration cycle while minimizing environmental impact.
Key points regarding refrigeration systems with blended refrigerants include the temperature glide during phase changes, which occurs because the different components may evaporate or condense at different rates. This could complicate both charging and servicing of the system. It's especially important during the charging process to ensure the correct composition of the blend is maintained, typically by charging in the liquid state to prevent fractionation of the mixture.
The efficiency and environmental aspects of heat pumps, air conditioners, and refrigerators depend highly on the Coefficient of Performance (COP). The COP is better when the temperature difference (T₁ and To) within the system's cycle is smaller. In very cold climates, heat pumps are less efficient because the difference in temperature between the inside and outside is much greater, requiring more work for heat transfer.