Optimization of diffuser for water based thermal energy storage system for commercial building

Wong, Bryan Thim Loong (2026) Optimization of diffuser for water based thermal energy storage system for commercial building. Final Year Project, UTAR.

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Abstract

This research attempts to analyse and optimise the performance of water diffusers in a thermal energy storage tank through computational fluid dynamic (CFD) analysis. The concept and application of thermal energy storage were detailed initially. The factors affecting the performance of a thermal energy storage tank were analysed and listed through many literature reviews from other researchers. The performance of three different perforated plate diffuser configurations of ‘A’, ‘B’ and ‘C’ were studied under charging and discharging cycles during this research. The differences between the three diffusers are the spacing of holes between one another, total number of holes present and perforation surface area on the plate diffusers with Configuration ‘A’ having the smallest spacing between holes, greatest number of holes present and largest total perforation surface area followed by Configuration ‘B’ and finally Configuration ‘C’ with the largest spacing between holes, least number of holes present and smallest total perforation surface area. ANSYS CFX software was used to carry out the CFD simulations. A prototype tank was fabricated and tested to verify the findings. Configuration ‘C’ with the least perforation area and number of holes produced the thinnest thermocline layer of 0.992 m and 0.549 m after eight hours of charging and discharging respectively but with the largest result deviation compared to the initial thermocline layer thickness at 4 hours as a large thermocline layer is formed after the layer passes through the first perforated plate diffuser. Configuration ‘A’ with the most perforation area and number of holes produced the most consistent results with the least deviation in thermocline thickness between partial and full charging of 0.181 m, likewise for the discharging cycle as well of 0.276 m, due to the reduction in water jet velocity through the perforations. Thus, Configuration ‘A’ was chosen as the ideal configuration of perforated plate diffuser as it is more practical in a commercial setting where it would be constantly charging and discharging. Keywords: Sensible thermal energy storage, hybrid diffuser, computational fluid dynamic, commercial buildings, exergy efficiency, water-based TES

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