Thermodynamic software - A toolbox for energy

Modeling thermodynamic systems is considered a particularly difficult exercise for many reasons, because :

• the discipline calls on certain fundamental concepts that are difficult to master, such as internal energy, enthalpy and entropy;

• The calculations to be performed are almost always complex, both formally and numerically, especially in closed systems;

• even the simplest laws are highly non-linear.

What's more, when we look a little deeper, we come to distinguish two levels in the models:

• phenomenological models that provide access to the calculation of thermodynamic cycles, independently of the choice of a particular component technology;

• technological dimensioning and simulation models for non-nominal operation, which not only provide the same results as the previous ones, but also, thanks to the inclusion of additional equations specific to the chosen technologies, enable the various components to be precisely dimensioned, and then, once this work has been completed, to study the behavior of the system in question outside the operating conditions for which it was dimensioned.

This second class of models has so far been little studied, despite being the only one that can really answer the questions most modelers have. This somewhat paradoxical situation stems from the fact that such models are much more difficult to write and solve than cycle calculations, which are often already quite complex. In the absence of appropriate tools, modellers have so far been forced to limit their ambitions in this area.

It should be noted that what we refer to as non-nominal operation corresponds to the stabilized operation of a plant under operating conditions different from those for which it was designed: it is not a question of studying the rapid transient operation resulting, for example, from the actuators of a control system.

The Thermoptim software package was designed to facilitate and secure the modeling of energy conversion technologies. Its functionalities now enable it to carry out cycle studies as well as non-nominal simulation of various systems, as shown in this article.

Used in more than 120 educational establishments and by numerous industrial companies, Thermoptim has enabled a profoundly new approach to modeling applied thermodynamics.

The interest it has aroused since its initial release in 1998 by Techniques de l'Ingénieur under the name ThermoCalc has justified the development of numerous digital teaching resources designed to make it easier...