Papers by Johannes Brunnemann

Title:	Numerically Robust Six-Equation Two-Phase Flow Model for Stationary and Moving Systems in Modelica
Authors:	Johannes Brunnemann, Ales Vojacek and Thomas Koch
Abstract:	We present a physics based Modelica finite volume flow model that separately balances vapour and liquid phase. By using extensive state variables and a special mass flow regularisation, the model can cope with the possible vanishing or emerging of a phase in a numerically robust way. Although at prototype stage, the model already exhibits all required capabilities. These are demonstrated in feature testers and in a model of a natural convection driven cooling cycle operating under external acceleration forces.
Keywords:	two phase flow, six equation model, cooling cycle, natural convection, moving systems, ClaRa library
Paper:	full paper
Bibtex:	@InProceedings{modelica.org:Brunnemann:2021, title = "{Numerically Robust Six-Equation Two-Phase Flow Model for Stationary and Moving Systems in Modelica}", author = {Johannes Brunnemann and Ales Vojacek and Thomas Koch}, pages = {539--548}, doi = {10.3384/ecp21181539}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }

Title:	Long Term Technical and Economic Evaluation of Hydrogen Storage Technologies for Energy Autarkic Residential Complexes
Authors:	Lucas Schindhelm, Ales Vojacek and Johannes Brunnemann
Abstract:	We present an assessment of different types of hydrogen storages used as long term energy buffers for a local community complex of households in terms of economics and energy autarky. The models used in this study are partly based on the TransiEnt Modelica Library, which is being developed for the dynamic simulation of coupled energy supply systems with high shares of renewable energies. It turns out that dynamic simulations are mandatory in order to optimise the system parameters. Starting from a best case evaluation of a one year linear optimisation we develop a forecast based control logic of the whole energy system, including its physicalities. Based on our results, a storage consisting of pressurized gas bottles has proven to be the most favourite solution in terms of price and level of autarky. A liquid organic hydrogen carrier might be a competitive alternative for larger urban districts.
Keywords:	energy autarky, costs, long term, hydrogen storage, control logic, TransiEnt, linear optimisation
Paper:	full paper
Bibtex:	@InProceedings{modelica.org:Schindhelm:2021, title = "{Long Term Technical and Economic Evaluation of Hydrogen Storage Technologies for Energy Autarkic Residential Complexes}", author = {Lucas Schindhelm and Ales Vojacek and Johannes Brunnemann}, pages = {597--606}, doi = {10.3384/ecp21181597}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }