Thermo-hydro-mechanical analysis of cement-based sensible heat stores for domestic applications

The thermo-hydro-mechanical behaviour of a water-saturated cement-based heat store for domestic applications has been investigated. Numerical simulations have been employed to locate the critical regions during thermal loading, for which analytical solutions have been derived and validated by numerical simulations. The analytical solutions allow a fast screening of materials and design parameters in relation to the stresses induced by thermomechanical loading. Maximum stresses in the system have been quantified based on the thermomechanical properties of three heat exchanger materials selected by design engineers and of the filling material. Sensitivity analyses indicate that the stress distribution is very sensitive to the thermal expansion coefficients of the involved materials. The results of this study can serve as a guide line for the design of the present and similar heat storage systems. The analytical solution developed is a fast and robust method for the evaluation of stresses around heat exchangers embedded in a solid material and can serve as a tool for design optimisation.