PARAMETRIC ANALYSIS OF THE ELIOSLAB HIGH TEMPERATURE (>800°C) SENSIBLE HEAT STORAGE SYSTEM BY MEANS OF NUMERICAL SIMULATIONS

摘要

This work has been realized in the framework of the Elioslab project, financed by the Italian Ministry of Education, University and Research (MIUR), which aims to create a research platform in order to develop components and systems for the production and utilization of medium and high temperature heat using concentrated solar energy. As regards high temperature heat production, a 30 kW solar furnace that consists of a heliostat with flat mirrors and a parabolic concentrator with off-axis alignment is being realized in order to achieve a solar radiation concentration of about 2000 suns (2000 kW/m~2). The energy flux relative to the concentrated radiation will be converted to high temperature heat by a cavity receiver cooled with CO_2, and finally transferred to a device operating at high temperature, as a water splitting reactor for hydrogen production. Because of the intermittency of solar radiation, a high temperature (> 800°C) packed bed sensible heat storage system has been developed in order to provide continuity to the user operation. The present work focuses on the parametric analysis that has been carried out in order to evaluate the set of variable parameters that maximizes the efficiency of the heat storage system of the solar furnace. The charging and discharging phases of the heat storage tank have been numerically simulated by means of an ad-hoc analytical model that takes into account the conductive, convective and radiative heat transfer as well as turbulent diffusion due to the solid-fluid interaction.