Jets of high-speed steam are used in spray cleaning. Steam at 15.0bar with 150C of superheat is fed to a well-insulated valve at a rate of 1.00 kg/s. As the steam passes through the valve, its pressure drops to 1.0 bar. The outlet stream may be totally vapor or a mixture of vapor and liquid. Kinetic and potential energy changes

Chapter 7, Problems #38

Jets of high-speed steam are used in spray cleaning. Steam at 15.0bar with 150°C of superheat is fed to a well-insulated valve at a rate of 1.00 kg/s. As the steam passes through the valve, its pressure drops to 1.0 bar. The outlet stream may be totally vapor or a mixture of vapor and liquid. Kinetic and potential energy changes may be neglected.

(a) Draw and label a flowchart, assuming that both liquid and vapor emerge from the valve.

(b) Write an energy balance and use it to determine the total rate of flow of enthalpy in the outlet stream (H out = mlHl + mvHv.). Then determine whether the outlet stream is in fact a mixture of liquid and vapor or whether it is pure vapor. Explain your reasoning.