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

The purpose of the expansion valve in a vapor-cycle cooling system is to control refrigerant flow and pressure. This component acts as a regulator that reduces the pressure of the refrigerant as it exits the high-pressure side of the system and enters the evaporator. By doing so, it allows the refrigerant to expand and evaporate, transitioning to a low-pressure vapor state. This process is essential because it sets the stage for the absorption of heat from the environment inside the cabin, facilitating the cooling effect.

Controlling the flow and pressure is critical because it ensures that the system operates efficiently, maintaining the proper temperature and pressure levels for effective heat exchange. The incorrect options involve functions that are not performed by the expansion valve itself. For example, absorbing excess heat is the role of the evaporator, converting vapor to liquid involves the condenser, and compressing the refrigerant is the task of the compressor. Understanding the specific functions of each component helps clarify how they collectively contribute to the operation of a vapor-cycle cooling system.