Seasonal thermal storage systems represent an efficient and long-term method for storing thermal energy in a medium, which is usually water. The aim of this thesis was to develop a simplified thermo-hydraulic model of a seasonal thermal storage system in the Python programming environment. We designed the numerical model of the thermal storage system based on existing models and simplified it with certain assumptions to reduce mathematical complexity and computational time. The developed model allows for the analysis of cylindrical storage tanks and permits the use of up to three inlets or outlets, located at the top, bottom, and volumetric center of the storage tank. We validated the model for the basic operational modes of the thermal storage system: charging, discharging, and standby. With the help of measurement data from a seasonal thermal storage system that is part of the solar thermal plant in Dronninglund, Denmark, we also validated the dynamic operation mode of the storage tank. Subsequently, we performed a parametric analysis of the thermal storage tank's operation in a smaller district heating system, where the storage tank was charged via solar collectors and supplied the heat demand of a residential building.
|
