Research on prediction of non-uniform heated rod bundle CHF based on subchannel analysis code coupling modified mechanistic model

An absence of accurate research on the mechanism of CHF on non-uniform heated rod bundle. This work presents a numerical simulation of subchannel analysis code CTF coupling modified liquid sublayer dryout model to validate experimental results of HTRF. The study indicated that the deviation between the predicted CHF results and experimental results within a range of ± 30 % under widely operating conditions. Simultaneously, the method can accurately predict the position of CHF. The CHF of the axial uniform heated bundle occurs at the outlet of the central hot subchannel. While the CHF occurs in the downstream of the central hot subchannel of the axial cosine heated rod bundle. In NHR-200Ⅱ rod bundle, the predicted local CHF steadily rises when local mass flow rate increases or local quality falls. The decrease in flow rate into the liquid sublayer and the reduction in the lift force of the vapor blanket cause this phenomenon.