Control system for an expansion valve regulating refrigerant to an evaporator of a climate control system

摘要

A control system for an expansion valve and evaporator of an air conditioner system is provided that comprises an expansion valve having a valve element that is movable relative to a valve port for varying an opening area to regulate the flow of refrigerant to an evaporator coil. The evaporator coil has an inlet and an outlet, and is configured to conduct heat to a refrigerant flowing through the evaporator coil, where the exiting refrigerant temperature is dependent on the refrigerant flow rate. The control system for controlling the expansion valve includes an evaporator coil outlet temperature sensor, which is configured to sense the temperature of refrigerant within the evaporator coil near the outlet of the evaporator coil. A controller is in communication with the evaporator coil outlet temperature sensor for sensing temperature of refrigerant near the evaporator outlet, and is configured to determine a control set point based on the refrigerant temperature near the evaporator outlet. The control set point is used to determine a valve opening area to regulate refrigerant flow into the evaporator such that temperature of refrigerant at the evaporator outlet is within a temperature band having a lower bound within 12 degrees Fahrenheit above the liquid-to-vapor transition temperature.