What role does the expansion valve play in the refrigeration cycle?

The expansion valve plays a crucial role in controlling the flow of refrigerant in the refrigeration cycle. It serves as a critical point where the high-pressure refrigerant, which has been condensed into a liquid in the condenser, is allowed to expand and reduce its pressure as it enters the evaporator coil. This process transforms the liquid refrigerant into a low-pressure mixture of liquid and vapor.

By regulating the flow rate of refrigerant into the evaporator, the expansion valve ensures that the system runs efficiently and effectively. It allows just the right amount of refrigerant to enter the evaporator for the cooling process based on the thermal load demands. This precise control is essential for optimizing the heat absorption in the evaporator, thereby enhancing overall system performance.

If the refrigerant flow were not properly controlled, the system could either flood (too much refrigerant) or starve (too little refrigerant) the evaporator, leading to inefficiencies and possible system damage. Thus, the primary function of the expansion valve is indeed to regulate the refrigerant flow, which is why it is the correct answer in this context.