Session: 08-08: Computational Fluid Dynamics (CFD) and Applications - VIII

Paper Number: 135643

135643 - Impact of Tube Fouling on Steam Generator Performance Using a Thermal-Hydraulic Code 

Abstract: 

Abstract

Accumulation of fouling on the heat transfer tube surfaces of steam generators significantly impacts the thermal performance, exerting a substantial influence on the economic viability of nuclear power plants. The fouling layer on the heat transfer tube surfaces possesses a complex porous structure, with porosity changing in response to variations in fouling thickness, posing significant challenges for numerical simulations. In this study, based on a self-developed thermal-hydraulic calculation program for steam generators, a variable porosity model is introduced to calculate and analyze the effects of various fouling pore structures on the thermal performance. The thermal-hydraulic model employs a porous media model to simulate heat transfer tube resistance, incorporating a fouling model into a first-second coupling model to facilitate heat exchange on both sides. The variable porosity model considers only the impact of changes in pore structure on thermal conductivity and does not alter the convective heat transfer mode on the secondary side. Research results underscore that the distribution of fouling porosity and the phase of the fluid filling the pores are pivotal factors influencing the thermal performance of steam generators. The fouling porosity distribution exhibits pronounced stratified characteristics, with the parameter named Caging employed to characterize the development degree of the dense fouling layer. When Caging values are 0.5 and 0.25, with fouling average porosities of 0.48 and 0.6, the accumulated fouling mass over five years is 76.4 and 70.8 kg, respectively. The fouling thickness is 55.9 and 85 μm, resulting in a decline in the thermal power of a steam generator with an initial power of 966 MW by 14.5 and 21.8 MW. Calculations were conducted for three scenarios within fouling pores: entirely liquid, partially liquid, and entirely gaseous. Results indicate that the phase within the porous transition layer significantly influences thermal power. Thermal power for entirely liquid and partially liquid scenarios is 951.4 and 951.5 MW, respectively, whereas the entirely gaseous scenario exhibits a decrease in thermal power of nearly 13 MW compared to the other two situations. The paper also analyzes the impact of changes in porosity on the local flow field and heat transfer of steam generators. Due to fouling primarily accumulating on the hot side, an increase in porosity leads to a reduction in heat flux density on the hot side, resulting in decreased flow velocity and void fraction, while the opposite effect is observed on the cold side. This study contributes to an enhanced understanding of the impact of fouling pores on the thermal performance of steam generators.

Keywords: Fouling porosity, Steam generator, Thermal performance, Numerical simulation

Presenting Author: Xiong Zhenqin Shanghai Jiao Tong University

Presenting Author Biography: Associate Professor at SJTU, with main research interests in fouling deposition and thermal performance of steam generators, steam water separation efficiency, flow induced vibration of heat transfer tubes, etc

Authors:

Liu Jing Shanghai Jiao Tong University
Li Zhen Fujian Fuqing Nuclear Power Co., Ltd
Xiong Zhenqin Shanghai Jiao Tong University
Gao Yuan Fujian Fuqing Nuclear Power Co., Ltd
Lin Yuchen Fujian Fuqing Nuclear Power Co., Ltd
Shi Linpeng Shanghai Jiao Tong University