What determines the position of the thermostatic expansion valve in a vapor-cycle cooling system?

The position of the thermostatic expansion valve in a vapor-cycle cooling system is primarily determined by the temperature and pressure of the refrigerant in the outlet. This valve regulates the flow of refrigerant into the evaporator based on the conditions of the refrigerant it senses. When the refrigerant is at a higher temperature and pressure at the outlet, the valve adjusts its opening to control how much refrigerant enters the evaporator. This ensures that the evaporator can maintain the desired temperature and pressure conditions for efficient cooling.

In contrast, other factors such as ambient temperature, cabin altitude, or cylinder pressure in the compressor may influence system performance but do not directly dictate the position of the expansion valve. The focus is on the refrigerant's state at the outlet, which directly affects the valve's operation and overall system efficiency.