Supersaturated (meta-stable) steam property check:\nThe density of supersaturated steam is approximately how large compared to the ordinary saturated vapour at the same pressure?

Introduction / Context:
Supersaturated (meta-stable) flow can occur during rapid expansions where condensation lags thermodynamic equilibrium. Understanding how properties like density compare with saturated values is useful for nozzle calculations and interpreting departures from equilibrium charts.

Given Data / Assumptions:

• Comparison at the same pressure.
• Supersaturation implies delayed condensation, not a vastly different equation of state at a given p.
• Small deviations from equilibrium in density are expected at identical pressure for steam near saturation.

Concept / Approach:
At a given pressure, the vapour density of a meta-stable (supersaturated) state is close to that of the equilibrium saturated vapour because the state point lies near the saturation dome but on a non-equilibrium path. The principal differences show up in temperature, wetness, and nucleation behavior rather than order-of-magnitude density changes. Hence, the density is approximately the same, not 2×, 4×, or 8× larger.

Step-by-Step Solution:

Verification / Alternative check:
Experimental nozzle studies show slight departures in temperature and non-equilibrium wetness, but density changes at the same pressure are not multiples as large as 2× or more; they are comparatively small.

Why Other Options Are Wrong:

• 2×, 4×, 8×: These would imply radical changes inconsistent with steam property behavior at fixed pressure.

Common Pitfalls:
Equating supersaturation with superheat; supersaturated (meta-stable) refers to delayed condensation below saturation temperature, not necessarily a large density jump.

Final Answer:
same as