In order to drastically increase the share of renewable energy sources, the EU has highlighted the necessity of combining heat pumps with thermal energy storage systems.
The cheapest and most widely used type of thermal energy storage is sensible thermal energy storage (STES) using a water tank.
Recently, the group of Prof. De Paepe has developed a novel method for experimentally characterizing thermal energy storage systems: the charging time energy fraction method. The method allows to characterize the dynamic behavior of thermal energy storage systems which was previously not possible using classic heat exchanger techniques.
The charging time energy fraction model allows to implement the STES in a dynamic model of an energy system (i.e. a house with PV panels and a heat pump). If the coefficients of the model can be predicted based on the geometry of the tank, the charging time energy fraction model can also function as a design model.
The master thesis will first redesign and commission the test setup shown in Figure 1. In the next step, a series of charging and discharging tests will be performed and the charging time energy fraction model will be fitted to the experiments. The resulting model will be used in future dynamic building system simulations.
Besides the experimental work, two lower order models will be used to predict the experimentally fitted charging time energy fraction coefficients. The first lower order model is based on a single control volume approach and heat transfer correlations. The second lower order model is based on the integration of a constant boundary characterization. If successful the results of this master thesis will serve as a basis for a journal publication.