Sensitivity analysis of efficiency thermal energy storage on selected rock mass and grout parameters using design of experiment method

• Paper propose a new methodology to sensitivity study of underground thermal storage.
• Using MDF model and DOE technique significantly shorter of calculations time.
• Calculation of one time step was equal to approximately 57 s.
• Sensitivity study cover five thermo-physical parameters.
• Conductivity of rock mass and grout material have a significant impact on efficiency.

The aim of this study was to investigate the influence of selected parameters on the efficiency of underground thermal energy storage. In this paper, besides thermal conductivity, the effect of such parameters as specific heat, density of the rock mass, thermal conductivity and specific heat of grout material was investigated. Implementation of this objective requires the use of an efficient computational method. The aim of the research was achieved by using a new numerical model, Multi Degree of Freedom (MDF), as developed by the authors and Design of Experiment (DoE) techniques with a response surface. The presented methodology can significantly reduce the time that is needed for research and to determine the effect of various parameters on the efficiency of underground thermal energy storage. Preliminary results of the research confirmed that thermal conductivity of the rock mass has the greatest impact on the efficiency of underground thermal energy storage, and that other parameters also play quite significant role.