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Free Aspen HYSYS Alternatives — Chemical Process Simulation Without a Licence

Free Aspen HYSYS Alternatives — Chemical Process Simulation Without a Licence

Aspen HYSYS and Aspen Plus are the tools every chemical engineer learns about, and their licence is among the most expensive in engineering software. For most small offices and final-year projects that is simply not an option. The good news: free process simulation exists and works, and it rests on the same thermodynamic models. The difference is in the depth of the databases and the number of ready-made equipment models.

Process simulators

1. DWSIM

The most complete open-source alternative. You build a flowsheet by drag and drop — pumps, heat exchangers, reactors, distillation columns, separators — and pick a thermodynamic model from a wide list: Peng-Robinson, SRK, NRTL, UNIQUAC and more. It runs on Windows, macOS and Linux, and supports the CAPE-OPEN standard, so external components can be plugged in.

What's missing: a smaller component database than Aspen's, and on very complex systems convergence is less robust.

2. COCO

A free process simulator from AmsterCHEM, built entirely on the CAPE-OPEN standard. Particularly good for teaching: it makes it easy to see how each unit receives a stream, calculates and passes it on. It works together with ChemSep for separation columns.

3. ChemSep LITE

Design of distillation, absorption and extraction columns, with equilibrium-stage and rate-based models. This is the free version — limited in problem size, so it suits learning and small problems rather than a full industrial column.

Thermodynamics and kinetics

CoolProp gives thermophysical properties for hundreds of fluids — steam, refrigerants, natural gases — from Python or directly from Excel. It is a modern replacement for steam tables, and useful in any refrigeration cycle or steam system calculation.

Cantera is the open standard for chemical kinetics and combustion — reaction mechanisms, flame temperature, ideal reactors. Common in engine, turbine and fuel cell research.

Multiphase flow and reactors

MFIX, from the US Department of Energy, simulates gas-solid-liquid flow: fluidised beds, reactors and pneumatic conveying. For more general CFD there is a separate article on free CFD software.

Quick calculators

ChemEnggCalc gathers chemical engineering calculators — mass and energy balances, heat transfer, flow and heat exchangers — with the formula shown next to the result, so it is easy to check. And for water chemistry — scaling, dissolution and saturation indices — PHREEQC is the accepted tool.

So which one

A full process flowsheet: DWSIM. Teaching and understanding the principles: COCO with ChemSep. Fluid properties in a refrigeration or steam cycle: CoolProp. Combustion and kinetics: Cantera. A quick formula check: ChemEnggCalc.

Further reading