 In order for the higher pressure liquid to cool down, the pressure of refrigerant entering the evaporator is reduced via the expansion valve, by restricting flow, allowing isenthalpic expansion back into the vapor phase to take place at a lower temperature.A TXV type expansion device has a sensing bulb that is connected to the suction line of the refrigerant piping so that the temperature of the refrigerant that leaves the evaporator can be sensed.The gas pressure in the sensing bulb provides the force to open the TXV, therefore dynamically adjusting the flow of refrigerant inside the evaporator and, as a result, the superheat acquired by the refrigerant that exits the evaporator.