How does the expansion valve operate in a refrigeration system?

The expansion valve in a refrigeration system plays a crucial role in controlling the flow of refrigerant into the evaporator. Its primary function is to reduce the pressure of the refrigerant before it enters the evaporator. When the refrigerant passes through the expansion valve, it experiences a drop in pressure. This reduction in pressure also causes a drop in temperature, allowing the refrigerant to evaporate (change from liquid to gas) more easily in the evaporator, which is essential for absorbing heat from the surroundings.

When the refrigerant enters the evaporator at low pressure, it can absorb heat effectively. This is a vital part of the refrigeration cycle, as it allows the system to cool the air in the space being conditioned. Without this pressure drop facilitated by the expansion valve, the refrigerant would not be able to adequately vaporize at the temperatures present in the evaporator, leading to a breakdown in the cooling effect of the system.