For more environmental friendly aircraft, different propulsion systems are considered. Either fuel cell or fully electrically driven aircraft come along with challenging heat dissipation tasks. An intelligent thermal management system is essential to prevent failures and to ensure a reliable operation of the propulsion system. The exploration space for appropriate cooling systems seems endless, hence it is vital to rely on robust modeling libraries that enable a quick design and simulation of different architectures. The open source DLR Thermofluid Stream Library (TFS) forms such a basis and proved to be expedient in that sense. This paper gives an overview of a complete fuel cell system for future aircraft that covers the most essential subsystems and is modeled solely of components contained in the TFS. The focus is on different cooling systems and methods that can be quickly investigated in the context of the overall fuel cell system throughout an entire flight mission.

The Contact Dynamics library extends the multi-body Modelica Standard Library with contact calculation to the environment, namely soft soil and hard obstacles. A focus is on terramechanics, i. e. wheels driving on soft and dry soil, and a handful of models are implemented. Additionally, a Hertz contact model for hard and elastic contact, between bodies themselves or to obstacles in the environment (e. g. rocks in the soft soil), is available as well. The capabilities of the library have been key in the development of rovers for planetary exploration such as the upcoming MMX mission to the Martian moon Phobos.

In this article, we examine the consequences of introduc-

ing a new construct into an equation-based language to

model infinitely fast processes. We do this by extending

the equation-based language Modelica with a special time

constant, Θ. Θ provides modelers with an additional lan-

guage construct that they can utilize both to improve per-

formance of numerical integration for existing models as

well as formulating and simulating models that existing

tools struggle with. We present two cases where clear net

benefits of introducing this new operator are illustrated.

The first being an artificial DAE-System using a mono-

tonic function, the second being an electrical circuit with

and without a parasitic capacitance.

Based on or observations we believe that by enabling

modelers to express common idealizations using Θwe can

improve both performance and maintainability, since ide-

alizations made by the modeler are encoded explicitly in

the model.