Numerical Analysis of Flow and Heat transfer in Sub-channel of Supercritical Water Reactor

Investigation on the thermal-hydraulic behaviour in the High performance Light Water Reactor (HPLWK) fuel assembly has obtained a significant attention in GENERATION-IV. In this paper. CED analysis is carried out to study the heat transfer behaviour of supercritical water in sub-channels of squared annular assembly. Effect of various parameters, e.g. thermal boundary conditions and pitch-to-diameter ratio on the thermal hydraulic behaviour is investigated. Boundary conditions, i.e., constant heat flux at the outer surface of cladding are applied. The effect of pitch-to-diameter ratio (MD) on the distributions of surface temperature and heat transfer coefficient (HTC) was analyzed For typical (gap between two rod) channel analysis, it is found that HTC increases with p/d first and then decreases significantly when p/d is <1.2. If P/D is larger than 1.2 heat transfer deterioration (HTD) occurs as main stream enthalpy is quite small. One/eight channel of 40 pin filet assembly show that the structure of the secondary flow mainly depends on the rod bundle configuration as well as the pitch-to-diameter ratio, whereas, the amplitude of the secondary flow is affected by the thermal boundary conditions, as well. Furthermore, the HTD under wire-wrapped spacer were evaluated. (C) 2013 The Authors. Published by Elsevier Ltd.