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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
A PRELIMINARY NUMERICAL STUDY OF A CONSTANT-PRESSURE SUPERCRITICAL FLUID-BASED THERMAL ENERGY STORAGE RESERVOIR DURING CHARGING
Submission Author:
Thaís Doll Luz , SC
Co-Authors:
Victor Dutra, Thaís Doll Luz, Alexandre Kupka da Silva
Presenter: Thaís Doll Luz
doi://10.26678/ABCM.ENCIT2022.CIT22-0680
Abstract
In solar thermal powered plants, the usage of thermal energy storage (TES) is arguably mandatory as it can mitigate the intermittency of solar radiation. Therefore, over the years, different materials were studied for TES applications, including supercritical fluids, which present high thermal capacitance and energy density when operating in conditions close to the critical point, justified by their intense thermophysical properties variation in these conditions. In this context, thermodynamic studies considering supercritical fluids operating at constant pressure show promising results, since the variation of isobaric specific heat is more intense than the isochoric version. Therefore, because of the inexistence of fully transient numerical studies dealing with the isobaric application of supercritical fluids for TES systems, this study develops a transient numerical study of a TES reservoir with a moving boundary under natural convection, such that the pressure of the reservoir, which is filled with supercritical carbon dioxide, a popular fluid for power cycles, is maintained at constant pressure. The TES charging process is promoted by a small heat source, which is allocated at the bottom of the reservoir. Four operational conditions were simulated, since four initial temperatures of the fluid domain were tested for a constant pressure operation of 16 MPa. The preliminary results show that the heat transfer coefficient increases when the pseudocritical temperature is found between the initial temperature of the fluid and the temperature of the heat source.
Keywords
supercritical carbon dioxide, Thermal Energy Storage, Natural Convection, transient study, constant pressure operation
