Supersaturated steam flow through a nozzle vs. stable (equilibrium) flow When steam expands with supersaturation (delayed condensation), how does the available heat drop compare to a stable (equilibrium) expansion? Choose the correct option.
Mechanical Engineering
Steam Nozzles and Turbines
Difficulty: Medium
Choose an option
Answer
Correct Answer: Increases
Explanation
ConceptSupersaturation delays condensation, so steam expands further in a metastable state before nuclei form. This permits a larger effective pressure/enthalpy drop across the nozzle prior to condensation (commonly evidenced by slightly higher exit velocity and mass flow than the equilibrium prediction).
ImplicationBecause of delayed phase change, the available heat drop (and thus attainable jet kinetic energy) tends to be higher than under fully stable equilibrium expansion at the same inlet and back pressures.
Final AnswerIncreases