Water is throttled (in a constant-enthalpy process) across a valve from 20.0 MPa and 260° C to 0.143 MPa. Determine the temperature of the H₂O downstream of the valve. What is the physical state of the H₂O (i.e., superheated vapor, subcooled liquid, etc.)? Sketch the process on a T–s diagram. Include the vapor dome and the pressure contours at the initial and final pressures.