Ther­mal Bridges in the Enve­lope of Large-Scale Ther­mal Energy Stor­age

Assignment/Task

Large-scale Thermal Energy Storage systems are an important component to support the decarbonization of District Heating networks through an increased penetration of energy from renewable energy sources. The high investment costs associated to their construction and their complex thermodynamic behaviour require a detailed pre-design phase that is able to take into account different aspects concerning their operation and interaction with other elements of the grid, their geometry and their thermal envelope. This last aspect is particularly critical, as the materials involved need to be able to withstand high temperatures and guarantee long lifetime. Thermal bridges within the envelope are therefore an important aspect, as they affect the quality of the stored energy and the quality of the surrounding ground.

Workflow and Methodology

The aim of the work is to investigate the effect of local thermal bridges within the TES envelope, due to geometric and material irregularities (i.e., internal uninsulated walls, cover limits). These elements are identified and modelled in 2D using a finite-element tool (therm, COMSOL Multiphysics) that allows to investigate the local temperature distribution within the materials and to derive the linear thermal transmittance of the specific thermal bridge.

Acquired Qualification

The student will learn how to apply the concepts of building physics to other fields, and to critically assess the interaction between design, heat transfer mechanisms and final performance that needs to be considered in engineering applications. In terms of specific skills, the student will learn how to establish simplified numerical simulations in terms of boundary conditions definition, material properties research and postprocessing of the simulation results.