Heat Transfer Analysis of Air Expansion in Surge Vessels Using Large Eddy Simulation (LES)

Abstract

Surge vessels are water storage devices that maintain a consistent supply of water to a pipeline system when one or more pumps fail. A surge vessel has compressed air on top and usually water on the bottom. The heat transfer during the expansion processes of the air pocket is of great interest since the heat transfer behavior significantly affects the size of the surge vessels. Thus their thermal behavior is of great importance.
Two approaches are mainly applied to describe this heat transfer process: the classic polytropic method and the rational heat transfer (RHT) model. The polytropic model has been used for years to describe the heat transfer behavior. The RHT model can contain a detailed estimation of all heat transfer terms. This report will specifically examine the two models, highlight the advantages and disadvantages identified in current related research, and clarify the research approaches.
To address this need, the research employs both mathematical calculations and Computational Fluid Dynamics (CFD) simulations. This involves calculating various heat transfer processes and validating the simulation results against experimental data. The LES model is used to simulate the complex process of air pocket expansion within the surge vessel.
The validation process includes verifying the ideal gas model within the software, assessing mesh resolution, and evaluating the chosen models and solvers. A comparison of simulation results with experimental data from a separate case is included, providing a robust validation.
The results reveal detailed insights into the temperature and velocity fields within the surge vessel, highlighting temperature variations at probes and comparing findings with scaled models and mathematical calculations. A comparative analysis of simulation results against experimental data and mathematical calculations is also presented.
The findings of this research offer significant insights into the heat transfer characteristics within surge vessels such as temperature distribution and amount of heat transfer. These contributions are essential for refining surge vessel design.