Steam Enthalpy Calculator

What this calculator does

Calculates specific enthalpy and supporting properties using the published IAPWS-IF97 equations for compressed liquid (Region 1), superheated steam (Region 2), and saturation states up to 623.15 K.

Inputs

State specification

Pressure MPa(a)

Temperature °C

Implemented range: IAPWS-IF97 Regions 1 and 2. Region 3 dense fluid, Region 5 very high temperature, and two-phase quality calculations are deliberately rejected rather than approximated.

The state is outside the implemented IAPWS-IF97 regions or lies on the two-phase boundary. Adjust pressure/temperature or use saturation mode.

Results

Specific enthalpy

—

State / region

—

Specific entropy

—

Specific volume

—

Isobaric heat capacity

—

Saturation temperature / pressure

—

State: —

What enthalpy represents

Specific enthalpy h combines internal energy with pressure–volume flow work. In steady-flow equipment, enthalpy differences are the natural basis for calculating heat transfer and shaft work per unit mass.

Why steam properties matter

Boilers, turbines, condensers, heaters, valves and heat exchangers operate across large changes in water and steam properties. Constant heat capacity or ideal-gas assumptions can create large errors near saturation and at high pressure.

How to specify a state

A single-phase state is defined here by pressure and temperature. On the saturation line, pressure and temperature are not independent, so choose saturation-at-pressure or saturation-at-temperature to obtain saturated liquid and vapor properties.

What IF97 regions mean

Region 1 covers compressed/subcooled liquid and Region 2 covers superheated vapor. Region 4 defines the saturation boundary. Dense-fluid Region 3, high-temperature Region 5 and two-phase quality calculations are intentionally outside this page’s scope.

Using enthalpy in balances

For a steady device with negligible kinetic and potential changes, heat or work per unit mass is commonly based on h2 − h1. A throttling valve is approximately isenthalpic, while turbine and pump analyses compare actual enthalpy changes with ideal reference processes.

Accuracy and limits

The page evaluates published IAPWS-IF97 equations and derivatives, not a simple table interpolation. Unsupported states are rejected. Always confirm pressure is absolute and verify critical design calculations with approved property software or tables.