NeqSim / documentation / screenshot / scripts / news

Welcome to the homepage of NeqSim (Non-Equilibrium Simulator). NeqSim has been developed at Department of Refrigeration and Air Conditioning, at the Norwegian University of Science and Technology (NTNU). The latest versions of the NeqSim source code and executables are available on request.


NeqSim is a dynamic process simulator specially designed to handle non-equilibrium situations. Common non-equilibrium processes include absorption, distillation, multiphase flow in pipelines, drying processes, hydrate formation and heat exchange. NeqSim also handles traditional equilibrium process calculations (equilibrium separators, equilibrium streams).


The applicability of NeqSim is in the areas of

  • Equilibrium calculations (TPflash / PHflash / TVflash .)
  • Multiphase flash calculations
  • Chemical equilibrium calculations (reactive equilibrium)
  • Electrolyte calculations (salts, amines)
  • Hydrate calculations (TP-flash, phase curves)
  • One phase pipe flow / Two phase flow (steady state / transient)
  • Absorption / Distillation (steady state / transient)
  • Freezing point calculations
  • Construction of Thermodynamic Property Charts (2D / 3D)
  • Parameter fitting (thermodynamic / fluid mechanics data)


NeqSim is built upon six base modules:


NeqSim is programmed in Java and is easily extendible with new modules. NeqSim implements Python (Jython) as a scripting language a powerful, easy and object oriented language. Python documentation is available here. Fast and easy Python scripts are automatically made with the toolbars in the GUI. NeqSim uses the Jext text-editor and the VisAd scientific visualization library.


The documentation is available here. A thesis work related to NeqSim is available here.

Example-scripts are available here.


Things I hope to implement in the near future are

  • Process Optimisation routines
  • Slug Flow Routines
  • Better GUI


The documentation is scarce at the moment but will hopefully be better soon.

You are welcome to send your comments to Even Solbraa.