Analysis of energy and exergy of a thermal storage system using multiple phase change material

A practical method for balancing supply and demand in renewable energy is cascade latent thermal storage.Thermal energy storage (TES) systems with phase change material (PCM) store energy at different temperature levels.This study aims to present the comparative energy and exergy efficiency analysis of single PCM and multiple-temperature PCM TES using different PCM in a temperature range of 100-200C.The analysis is carried out in three configurations: 1) single PCM with Hydroquinone, 2) single PCM with Catechol, and 3) Multiple-temperature PCMs with Hydroquinone and Catechol.In the first and second configurations, heat transfer fluid, i.e. therminol-66, flows in their respective individual PCM tanks and analysis is carried out.In the third configuration, i.e. multi-temperature PCMs, heat transfer fluid (HTF) flows in descending order of respective melting point.Energy and exergy efficiency were analysed regarding temperature and time during the charging and discharging cycles.From the analysis, the overall exergy efficiency using Hydroquinone and Catechol as PCM in the TES system in cascading is 38.57%, which is relatively higher than the exergy values of the single PCM, which indicates that by providing multi-grade thermal energies, multiple PCMs can increase thermal performance while also expanding the thermal energy's application scope.