97. The thermostatic expansion valve in a refrigeration system further opens when the diaphragm flexes downward. With all other conditions being the same, what single condition causes this?

An increase in sensing bulb temperature increases bulb pressure, which pushes the diaphragm downward, opening the thermostatic expansion valve further. The sensing bulb's pressure is directly related to its temperature; a rise in temperature increases pressure, which acts on the diaphragm. Evaporator pressure and superheat settings oppose valve opening, while a decrease in sensing bulb temperature would reduce bulb pressure and close the valve.