DE-13-C046 -- Use of Numerical Simulation and Optimization to Analyze the Design and Performance of a Chilled Water Thermal Storage Tank PDF

Chilled water thermal storage tanks are an efficient and economic option in HVAC design. The sensible cooling capacity, which is typicallygenerated and stored during lower demand periods, can serve many purposes such as reducing energy costs during peak demands, backing upcooling capacity during a power outage, and suppressing fire during a fire accident. The different density of water in varying temperatures, alongwith the buoyancy effect, can create thermal stratification in the tank, which plays an important role in the performance of the tank. The designachievement is judged by how long it takes the tank to discharge the chilled water at the design temperature. The performance can be affected bymany design parameters which make it difficult to analyze, and therefore is a good candidate for research. This paper shows how the full 3Dnumerical simulation and virtual design approach provide more detail and visualization of the flow field structure to improve the design. The maingoal was to design the chilled water storage tanks to provide at least fifteen minutes of chilled water at a specific temperature for a data centerduring a power outage. Different octagonal inlet and outlet diffusers with different sizes and locations of the slots in the diffusers were virtuallydesigned and their impacts on flow distribution, thermocline shape, swirl effect, and time amount of delivering cold water were investigated. Theoutcome was then used to optimize the design and provide solutions for improving the performance of the tank.