Thermostatic expansion valve

Use: To regulate flow of refrigerant with input of bulb.
Principle of controlling superheat: Joule thompson effect: Reduces pressure by throttling.
Compressor increases pressure which increases boiling point and condenser turns it into high pressure liquid. Expansion valve throttles high pressure liquid through orifice and pressure drop after orifice occurs. This expands the refrigerant allowing it to lower its boiling point to exchange heat with surroundings allowing it to fully evaporate and return to compressor as low pressure low temperature gas.
Superheat: Increasing boiling point by increasing pressure.
Degree of superheat: diff btw actual temp and saturation temp.
Thermostatic expansion valve divides high pressure and low pressure side.