thermo — The Complete Guide: Thermodynamic Properties and Phase Equilibria in Python
thermo is an open-source (MIT) Python library written by Caleb Bell, who is also behind the fluids library. It gives a process engineer what is usually hidden inside a commercial simulator: a property database of chemicals, thermodynamic models and equilibrium calculations — but as functions you can call from a script.
thermo
Caleb Bell
A Python library for thermodynamic properties and phase equilibria of thousands of chemicals and mixtures: equations of state, activity models and flashes.
Get it from the vendorWhat you get
- Chemical data — properties for thousands of chemical compounds.
- Equations of state — cubic models for gases and liquids under pressure.
- Activity-coefficient models — for non-ideal liquid mixtures.
- Flash calculations — phase split and composition at given pressure and temperature.
- Derived properties — density, enthalpy, heat capacity and vapour pressure.
When to choose it
When you need a repeatable, transparent process calculation: a spreadsheet turned into a script, a sensitivity study over dozens of cases, or a thermodynamic component inside a larger model. It does not replace a flowsheet process simulator, and results for complex mixtures are worth comparing against experimental data.
Related tools
For accurate pure-fluid and refrigerant properties — CoolProp. For pipe flow, pumps and valves — fluids. For flowsheet process simulation — DWSIM.
CoolProp
CoolProp Project
Thermophysical property data for over a hundred fluids, callable from any language.
Get it from the vendor
fluids
Caleb Bell
A Python library for flow calculations — pressure drop in pipes and fittings, pumps, compressible flow, control valves and flow meters.
Get it from the vendor
DWSIM
DWSIM Project
Steady-state and dynamic process simulation for chemical plants.
Get it from the vendor
Clapeyron.jl
Pierre J. Walker, Hon Wa Yew, Andrés Riedemann and contributors
Equations of state in Julia — SAFT, cubic, activity and COSMO-SAC models for phase equilibria and fluid properties.
Get it from the vendorThe bottom line
thermo is a comprehensive thermodynamics toolbox for anyone who calculates processes in code. Open source and completely free, including for commercial use.