Session: 15-13

Paper Number: 136502

136502 - Scaling of Horizontal Steam Generator Based on Three-Dimensional Thermal-Hydraulic Simulations 

Abstract: 

Thermal-hydraulics of horizontal steam generators of several scaled dimensions and power ratings are simulated and analysed with the in-house three-dimensional computational multi-fluid code. The predicted design operational conditions include water and steam velocity and pressure fields, void fraction distribution and two-phase flow swell level under steady state conditions. The scaled steam generator dimensions and power ratings are optimized through the set of thermal-hydraulic simulations with the aim to obtain the main operational requirements, such as: (i) moderate two-phase flow velocities around tubes in the bundles without induction of tube vibrations, (ii) the swell level position above tube bundles without occurrence of tubes dry-out, but with enough space in the steam dome for droplets gravitational separation, (iii) moderate steam velocities at the swell level surface in order to avoid as much as possible droplets entrainment from the swell level surface into the steam flow, as well as (iv) the liquid mass inventory on the steam generator shell side, since it provides the heat sink in case of loss-of-feedwater accident. In addition, the overall dimensions of the steam generator are kept within acceptable limits with the aim to provide efficient steam generator transport from the factory to the installation location. The obtained results are a support to the design of scaled down nuclear power plants with the application of small modular reactors of the PWR type. The applied in-house code for the numerical simulation of the steam generator thermal-hydraulics is based on the two-fluid model of two-phase flow. Mass, momentum and energy balance equations are written and solved for each phase and appropriate closure laws are applied for the prediction of interface transport processes, such as vapour-liquid interface friction, vapour and liquid wall friction and liquid evaporation rate under thermal non-equilibrium conditions. The system of balance equations is solved with the type of Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) that is modified for the two-phase flow conditions. The developed modelling approach and the numerical code are validated by comparing the numerical results with measured data available in the literature and obtained both at partial effect test experiments and under operational conditions of large-scale horizontal steam generators at nuclear power plants. It is found that the prediction of steam generator shell side two-phase flow conditions, the swell level position and the liquid mass inventory strongly depend on the liquid-vapour interface friction. Several correlations for the interface friction are tested and their reliability is evaluated.  

Presenting Author: Milos Lazarevic University of Belgrade, Faculty of Mechanical Engineering

Presenting Author Biography: Milos Lazarevic, research assistant, studied at the Faculty of Mechanical Engineering; University of Belgrade and obtained BSc and MSc degrees respectively in 2019 and 2022. Currently he is a PhD student at the University of Belgrade in the field of Nuclear Power Engineering at the Faculty of Mechanical Engineering. His research work includes thermal-hydraulics of nuclear steam generators. His PhD studies are supported by the Science Fond of the Republic of Serbia.

Authors:

Milos Lazarevic University of Belgrade, Faculty of Mechanical Engineering
Vladimir Stevanovic University of Belgrade, Faculty of Mechanical Engineering
Milan Petrovic University of Belgrade, Faculty of Mechanical Engineering
Sanja Milivojevic University of Belgrade, Faculty of Mechanical Engineering
Milica Ilic University of Belgrade, Innovation Centre of the Faculty of Mechanical Engineering