Dynamic modelling of an Ultra High Temperature PCM with combined heat and electricity production for application at residential buildings

The present study investigates the thermal performance of an ultra-high temperature (> 1000 °C) latent heat thermal energy storage system that utilizes silicon as a phase-change (PCM) material. Application of this system in the residential sector is studied, when integrated with a solar PV as an energy source and a hybrid thermionic-photovoltaic (TIPV) converter to produce both electricity and heat and subsequently cover corresponding domestic demand. A one-dimensional (1D) dynamic model has been developed in Dymola modelling tool for predicting the temperature profile and total charging and discharging time of the PCM heat storage system, as well as the produced thermal and electric power from the hybrid TIPV converter. A sensitivity analysis both for the melting and the solidification stage of the PCM has been performed based on key parameters, such as material thermal properties –including specific heat capacity, thermal conductivity and latent heat of fusion- and other operating and design parameters. The results have showed an increasing linear dependence of charging and discharging time on specific heat, latent heat of fusion and density and a decreasing dependence on thermal conductivity. Finally, the integration of the heat storage system on a building level has showed the potential for high coverage of either heat demand (over 100%) or electricity demand (over 69%) for a typical Southern European household, depending on the generation priority strategy followed.