Thermal hydraulics of rod bundles: The effect of eccentricity

• Published in: Nuclear engineering and design 2013-10, Vol.263, p.218-240
• Main Authors: Chauhan, Amit K., Prasad, B.V.S.S.S., Patnaik, B.S.V.
• Format: Article
• Language: English
• Subjects: Bundles; Computational fluid dynamics; Coolants; Eccentricity; Fluid flow; Flux; Heat transfer; Outlets
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2013.04.011

•Present CFD investigation explores, whole bundle eccentricity for the first time.•Fluid flow and thermal characteristics in various subchannels are analyzed.•Mass flux distribution is particularly analyzed to study eccentricity effect.•Higher eccentricity resulted in a shoot up in rod surface temperature distribution.•Both tangential and radial flow in rod bundles has resulted due to eccentricity. The effect of eccentricity on the fluid flow and heat transfer through a 19-rod bundle is numerically carried out. When the whole bundle shifts downwards with respect to the outer (pressure) tube, flow redistribution happens. This in turn is responsible for changes in mass flux, pressure and differential flow development in various subchannels. The heat flux imposed on the surface of the fuel rods and the mass flux through the subchannels determines the coolant outlet temperatures. The simulations are performed for a coolant flow Reynolds number of 4×105. For an eccentricity value of 0.7, the mass flux in the bottom most subchannel (l) was found to decrease by 10%, while the surface temperature of the fuel rod in the vicinity of this subchannel increased by 250% at the outlet section. Parameters of engineering interest including skin friction coefficient, Nusselt number, etc., have been systematically explored to study the effect of eccentricity on the rod bundle.