Wärmemanagement von Brennstoffzellen-Elektrofahrzeugen (English shop)

The aim of this work was the development of an optimised holistic thermal management system for a fuel cell electric vehicle that ensures operation even under extreme ambient conditions and driving states. For this purpose, the vehicle was modelled with regard to its cooling-relevant components by means of calculation models, the influencing variables were analysed on this basis, and concepts and control strategies were then derived.

If fuel cell technology is to represent a genuine alternative to an internal combustion engine drive in the vehicle, suitability for everyday use must, among other things, be ensured. This is discussed following a presentation of the operating principle of a fuel cell and of the fuel cell system with regard to the cooling requirement and the cold start behaviour.

The analysis of the heat sources and sinks under a wide variety of boundary conditions, both steady-state and transient, provides the starting points that lead to optimal cooling. In particular, the fuel cell stack, the heat exchanger, the vehicle fan as well as further components are examined, and a sensitivity analysis of the coolant circuit is carried out.

The concepts and control strategies derived from this are presented. In the optimisation of conventional cooling, the cross-counterflow arrangement of a vehicle radiator with double depth, a graphite foam heat exchanger and nanofluids are considered. A novel fan concept in which the fans discharge laterally is investigated. The integration of an R744 refrigeration system into the cooling system of a fuel cell vehicle, together with the resulting advantages and disadvantages, is shown. Likewise, a new cooling system in the form of two-phase evaporative cooling is developed. The potentials arising from a heat storage device or from a purpose design vehicle are described. Finally, the cold start is examined at a conceptual level.