Where is the greatest possible pressure drop typically found in a refrigeration system?

The greatest possible pressure drop in a refrigeration system is typically found in the expansion valve. The primary function of the expansion valve is to regulate the flow of refrigerant into the evaporator while reducing the pressure of the refrigerant. As the refrigerant passes through the expansion valve, it undergoes a rapid drop in pressure, allowing it to expand and cool before entering the evaporator where it absorbs heat.

While the evaporator and condenser do experience pressure changes due to the changes in refrigerant state and heat exchange processes, these changes are generally not as significant as the pressure drop across the expansion valve. The compressor, on the other hand, is designed to increase pressure, not to create a pressure drop. Thus, the correct answer emphasizes the role of the expansion valve in facilitating the essential pressure drop required for the refrigeration cycle to function effectively.