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K. Menzl:
"Thermal analysis of a lithium-ion battery module";
Supervisor: K. Ponweiser; Institut für Energietechnik und Thermodynamik, 2018; final examination: 2018-08-10.

Kreisel Electric is a company specialized in developing lithium-ion-battery packs based on cylindrical cells. One of the core components of the technology is the battery thermal management which has been carried out by direct cooling the cells using an non-conductive fluid. The aim of this thesis is to evaluate this method concerning heat transfer, heat distribution and pressure loss. The focus in the first part is to develop a lumped thermal model of a single cell to analyze the heat distribution within a cell. Based on this model, a detailed analysis of heat transfer and pressure loss of an 14P 1S module (14 parallel connected cells, 1 in series) was carried out. An examination based on the currently used cooling unit was done as well as an in-dept analysis on heat transfer and pressure loss with changing geometrical factors e.g. cooled cell surface, axial spacing between the cells as well as flowrate of the module. In the next step, the findings were extended to a 14P 12S module string (14 cells in parallel and 12 in series) with the focus on determining the temperature distribution between the battery modules. At the end of the thesis, possibilities of improvements like parallel flow distribution of the coolant between all modules and alternative coolants were examined.

Lithium-Ion / battery module / liquid cooled / battery temperature management