Investigation of dimensionless parameters and geometry effects on heat-transfer characteristics of liquid sodium flowing over a flat plate

摘要

To improve the cooling performance of a nuclear fuel element, it is important to appraise the effect of dimensionless parameters and the geometry on heat-transfer characteristic of sodium flowing over a nuclear fuel element. To fulfill this objective, the effects of geometry, Reynolds number (Re_H), conductivity ratio (N_(cc)), and dimensionless total heat generation parameter (Q_t) on a two-dimensional steady flow of liquid coolant flowing over a nuclear fuel element are studied. For this purpose, the stream function-vorticity formulation method is applied. Full Navier Stokes equations and energy equation for the fluid domain are solved concurrently with conduction equation of fuel element applying finite difference scheme. The pseudotransient form of the vorticity transport and energy equations is solved using the alternating direction implicit method. A line-by-line technique is used for other discretized equations. Isotherms are also plotted and studied in detail. From the obtained results it can be concluded that for fixed values of aspect ratio and Re_H there exists a critical value of Q_t and N_(cc) beyond and below which peak temperature in the fuel element surpasses its tolerable limit. The results can also be applied to minimize the peak temperature in the nuclear fuel element (hot spots).