Water at high pressure expands adiabatically to a lower pressure (throttled) through a partially-closed valve. You can vary the inlet temperature T₁ and outlet pressure P₂. The exit stream is a vapor-liquid mixture, and the outlet temperature is the saturation temperature at the outlet pressure. An energy balance (ΔH = 0) determines the fractions of liquid and vapor in the exit stream, and they are shown in the bar graph.