A New Lumped Thermal Resistance Heat Transfer Model for Fuel Pin Structure

AbstractThe lumped heat transfer methodology is simple, and the solution is very fast, so the lumped parameter approach has been widely used in thermal-hydraulic analysis for fuel pin heat transfer in nuclear reactors. In the conventional lumped thermal analysis of fuel pin structure, each component (such as a pellet, gap, cladding, etc.) is characterized by a concentrated bulk temperature (or averaged temperature), and a bulk thermal resistance. In contrast to this conventional lumped thermal resistance model, in this paper another kind of lumped thermal resistance heat transfer model for fuel pin structure has been developed. In this model, each fuel pin component is still represented by a concentrated lumped mean temperature node, while the location of the mean temperature position of each component is no longer set on the geometrical midpoint center; rather, it is assigned exactly onto the analytical temperature profile. Two thermal resistance elements are assigned for each component in this new model...