Enthalpy Entropy Diagram Steam

Overview

Engineering reference data for Enthalpy Entropy Diagram Steam in thermodynamics.

Key Formulas

First Law

$\Delta U = Q - W$

Energy is conserved — heat added minus work done.

Ideal Gas Law

$PV = nRT$

Relates pressure, volume, and temperature of an ideal gas.

Heat Transfer

$Q = mc\Delta T$

Sensible heat transfer.

Carnot Efficiency

$\eta = 1 - T_C/T_H$

Maximum efficiency between two temperatures.

Variables

Understanding the Diagram

The Enthalpy-Entropy (h-s) diagram, also known as the Mollier diagram, is a fundamental tool in steam engineering. It graphically represents the thermodynamic properties of water and steam, primarily plotting specific enthalpy (h) on the y-axis against specific entropy (s) on the x-axis.

How to Read the Diagram

• Constant Pressure Lines: Curve upward and to the right.
• Constant Temperature Lines: In the wet region (under the dome), they are horizontal. In the superheated region, they curve upward.
• Constant Quality Lines: Radiate from the critical point, dividing the wet region.
• The Saturation Dome: The enclosed curve where liquid and vapor coexist.

Reference Diagram

A printable version of the phase diagram for water can be found here: Water Phase Diagram (PDF)

Note: For precise calculations, always refer to official steam tables as the h-s diagram is a graphical approximation.

References

• Original Source