🔍 Key Concepts

• Thermostatic expansion valve (TXV) operation: how bulb pressure, spring pressure, and evaporator (equalizer) pressure balance to open/close the valve • What the sensor bulb is actually sensing in a refrigeration system (box temperature vs. suction line/evaporator outlet temperature) • Relationship between inlet vs. outlet temperature across an expansion valve and how superheat adjustment (adjusting screw direction) affects valve opening

💭 Think About

• On a TXV, which forces act to open the valve and which forces act to close it? Where does the external equalizer pressure act in that balance? • Where is the sensing bulb mounted in a real system, and what temperature condition is it meant to control: the room/box air, or the refrigerant leaving the evaporator? • Think physically about throttling: after liquid refrigerant is expanded across the valve, is the mixture typically warmer or colder than before the valve?

✅ Before You Answer

• Verify from the diagram which side (top or bottom of the diaphragm) the equalizer connection "K" is connected to, and whether that force tends to push the valve pin open or closed. • Confirm from standard TXV practice whether turning the adjustment screw inward (clockwise) increases or decreases spring force and superheat setting; then decide if the statement about counterclockwise rotation matches that behavior. • Check the normal temperature change across an expansion device: the refrigerant at outlet "B" vs. inlet "A" – which is colder in normal operation?