Nuclear coupled thermal hydraulic analysis of fast transient depressurization in supercritical channels

Abstract

Purpose The objective of the present work is to simulate the nuclear coupled thermal–hydraulic fast transient case studies for a vertically up-flowing supercritical pressure water channel of circular cross section. The emphasis is on analyzing the phenomenon of the deterioration in heat transfer (DHT) inside the channel subjected to sharp pressure variations. Design/methodology/approach The thermal–hydraulic model, THRUST, is integrated with the neutron point kinetic (NPK) solver to account for the non-linear interactions between the thermal–hydraulic and neutronic temperature and density reactivity feedback effects. The model implemented and studied accounts for the time-dependent reactor power and is used to analyze various steady-state and flow-induced transient case studies (time-dependent and step change in exit pressure). Findings There is good agreement in the predicted behavior of the supercritical water pressure system with that of the available experimental data for the steady-state case. The event of DHT in the second transient case (step decrease in exit pressure) is found to be more severe than that of exponential pressure decrease. Originality/value This study evaluated a novel implementation of the thermal–hydraulic model, THRUST, integrated with NPKs applied to supercritical pressure water systems for predicting DHT.

Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor

“…Regarding the above issue, there are many research viewpoints to the special heat transfer of supercritical fluids, e.g. operating conditions (Pizzarelli et al , 2015; Sunden et al , 2016) such as heat flux (a crucial factor to the abnormal heat transfer), turbulence models (Pandey et al , 2017; Gustavo et al , 2018), predictive correlations (Zahlan et al , 2017; Shokri and Ebrahimi, 2019), the effect of buoyancy force and thermal acceleration (Jackson, 2017; Yu et al , 2013), flow instability (Wang et al , 2013a; Yan et al , 2018) and enhanced heat transfer (Li et al , 2016; Xu et al , 2015), also including a transient study of HTD (Dutta and Giridhar, 2017). In our opinion, the effect of the wall conduction is a matter of concern due to the sensibility to the heat flux (Buzzi et al , 2019; Ehsan et al , 2018).…”