What is the main purpose of the expansion valve in refrigeration?

The main purpose of the expansion valve in a refrigeration system is to regulate the flow of refrigerant and reduce its pressure. The valve allows the high-pressure liquid refrigerant from the condenser to expand, which causes a drop in pressure as it enters the evaporator. This pressure drop is crucial because it enables the refrigerant to absorb heat from the surroundings effectively as it evaporates from a liquid to a gas in the evaporator coil. By controlling the flow and pressure, the expansion valve plays a vital role in maintaining the efficiency and effectiveness of the refrigeration cycle, ensuring optimal heat exchange and preventing issues such as flooding or starving of the evaporator.

The other choices do not accurately describe the role of the expansion valve; it does not increase the refrigerant's temperature, does not convert vapor to liquid, and while it does contribute to heat absorption indirectly, its primary function is flow regulation and pressure reduction.