Question 182Refrigeration & AC - Assistant Engineer

The correct answer is C. The expansion valve designed to maintain a constant evaporator pressure rather than a constant evaporator superheat is the thermostatic expansion valve (Type C in the illustration). This type of valve monitors the evaporator pressure and adjusts the refrigerant flow to maintain a specific evaporator pressure, which helps control the cooling capacity of the system. The other types of expansion valves, A, B, and D, are designed to maintain a constant evaporator superheat, which is the difference between the evaporator outlet temperature and the evaporator saturation temperature. These valves are used when it is more important to control the superheat rather than the evaporator pressure.