Which component is considered to be upstream of the evaporator in a refrigeration system?

The thermal expansion valve (TXV) is recognized as the component upstream of the evaporator in a refrigeration system. Its primary role is to regulate the flow of refrigerant into the evaporator by responding to the evaporator's pressure and temperature conditions. By doing this, the TXV ensures that the correct amount of refrigerant enters the evaporator to optimize the heat absorption from the surrounding environment, maintaining efficient operation and preventing issues such as flooding or starvation of the evaporator.

The TXV is positioned in the liquid line just before the evaporator, effectively controlling the refrigeration cycle starting from the point of refrigerant entry into the evaporator. This makes it critical for proper refrigerant management and overall system performance.

In contrast, the compressor is located downstream of the evaporator, as it pumps refrigerant vapor from the evaporator to begin the cycle anew. The condenser is also downstream, as it condenses the refrigerant vapor back into a liquid after exiting the compressor, while the accumulator serves to collect any liquid refrigerant that could return to the compressor, typically situated after the evaporator but before the compressor. Therefore, the thermal expansion valve (TXV) is definitively the component that is positioned upstream of the evaporator.