Innovative TES Design for Building Energy Management: Computational Investigation of RT-42 and RT-35 PCM Solidification Dynamics

Abstract

This study proposes an innovative approach for enhancing building energy efficiency by improving the efficiency of a chilled water-based cooling system using a thermal energy storage (TES) unit. The Chiller’s refrigerant is bypassed before entering the condenser through TES, which cools down and melts the PCM during the daytime. The excessive chilled water is passed through a phase change material (PCM) base TES unit, which stores the cold energy. That cold energy can be used for peak shaving and energy saving during the day. This study investigates numerically the solidification process of PCM RT-42 and RT-35, filled in a cylindrical TES system containing helical pipes for heat transfer fluid (HTF). As part of a larger perspective aimed at enhancing building energy efficiency, this research milestone focuses on the thermal behaviour and performance of the TES unit during the charging process. Numerical simulations were conducted using ANSYS Fluent to model the solidification process. The simulations analysed heat transfer rates, temperature distribution, and the progression of the solid-liquid interface within the storage unit. The solidification of two PCMs has been studied at 10m/s. The framework for the future of the experimental setup has been demonstrated to involve supplying chilled water from the chiller to a test room equipped with an FCU, where the room temperature is to be studied under varying chilled water flow rates. Crucially, the excessive chilled water flow is diverted and utilized to solidify a PCM in the TES unit. The cold energy will be used for cooling of refrigerant and to cool the return water from the building.