Large-Scale Thermal Energy Stores in District Heating Systems – Simulation Based Optimization
Abstract
Large scale thermal energy storage (TES) will be beneficial regardless of the future composition of the energy system. This paper presents a dynamic finite difference TES model, which is coupled to a 2D finite element model for the simulation of large-scale (underground) TES. With the geometrically flexible model TES can be simulated dynamically in district heating systems considering different types of construction and geometry (cylinder, truncated pyramid/cone, free-standing or buried) with variable distribution of the thermal insulation. The influence of the properties of the ground as well as approximately the influence of ground water on the thermal losses and the stratification can be investigated. In addition, the optimum distribution of the thermal insulation (bottom, wall, cover) can be determined for different applications of the TES (e.g. buffer or long- term). The model is implemented in the MATLAB/Simulink simulation environment. Simulation results for different storage types and geometries are presented.