Date of Award

1-1-2012

Document Type

Campus Access Dissertation

Department

Mechanical Engineering

First Advisor

Jamil A Khan

Abstract

PWRs fuel assemblies utilize spacer grids with flow mixing vanes to augment the coolant turbulence and improve heat transfer from the fuel rods. However, in the regions where the turbulence due to mixing vanes is the lowest, the heat transfer is the worst, resulting in higher temperatures and limiting conditions. Meyer (2007) used empirical correlations to predict heat transfer and friction factor for artificially roughened fuel rod bundles at High Performance Light Water Reactors, but their applicability has never been tested. Our team constructed a single heater element loop tester (SHELT) at the University of South Carolina (USC) to investigate the use of the artificial roughness for improved heat transfer in PWR rod bundles. The observations during the experiments included measurements of volumetric flow rate, electrical power, differential pressure, water and heated rod wall temperatures across the smooth and the ribbed surfaces. The team also developed and validated a Computational Fluid Dynamics (CFD) model using the Finite Element Method (FEM) to simulate the experimental test. The experiment and the CFD results indicate a heat transfer enhancement of approximately 50% at the rod surface with transverse square ribs. Therefore, this study suggests an achievable rod surface design for a significant heat transfer enhancement in PWR rod bundles.

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