What is the purpose of the expansion valve in a vapor-cycle cooling system?

The correct answer is that the purpose of the expansion valve in a vapor-cycle cooling system is to control refrigerant flow and pressure. The expansion valve plays a critical role in the refrigeration cycle by regulating the amount of refrigerant that flows into the evaporator. As the refrigerant passes through the expansion valve, its pressure is reduced, which in turn lowers its temperature. This cooling effect is essential for the refrigerant to absorb heat from the environment in the evaporator, thereby facilitating the cooling process within the system.

By managing the flow and pressure of the refrigerant, the expansion valve helps maintain the system's efficiency and effectiveness. This control is vital because it ensures that the evaporator operates at optimal conditions, resulting in effective cooling while avoiding issues such as freezing or inadequate heat absorption.

This understanding of the expansion valve's role is crucial in grasping how vapor-cycle cooling systems operate and the importance of each component in maintaining optimal performance.