Definition: Refrigeration system component that reduces refrigerant pressure from high (condenser) to low (evaporator) and meters refrigerant flow to evaporator.
Types:
- **Thermostatic Expansion Valve (TXV)**: Mechanical device, adjusts flow based on superheat
- **Electronic Expansion Valve (EEV)**: Electronically controlled, precise, more efficient
- **Capillary Tube**: Fixed restriction, simple, used in small systems
Why It Matters:
- Controls refrigerant superheat
- Improves system efficiency and capacity
- Protects compressor from liquid refrigerant damage
- TXV/EEV malfunction causes poor cooling or icing
Related Terms: Refrigeration Cycle, Superheat, Evaporator, Refrigerant Flow