Evaluation of thermophoretic effects on graphite dust coagulation in high-temperature gas-cooled reactors--颗粒学报PARTICUOLOGY

Wang, K., Yu, S., & Peng, W. (2020). Evaluation of thermophoretic effects on graphite dust coagulation in high-temperature gas-cooled reactors. Particuology, 51, 45-52. https://doi.org/10.1016/j.partic.2019.09.001

Evaluation of thermophoretic effects on graphite dust coagulation in high-temperature gas-cooled reactors

Kaiyuan Wang ^a, Suyuan Yu ^a, Wei Peng ^b *

a Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
b Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, Key Laboratory of Advanced Nuclear Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084, China

10.1016/j.partic.2019.09.001

Volume 51, August 2020, Pages 45-52

Received 13 June 2019, Revised 8 August 2019, Accepted 3 September 2019, Available online 18 November 2019, Version of Record 11 April 2020.

E-mail: pengwei@tsinghua.edu.cn

Highlights

• Thermophoretic effects on dust coagulation are analyzed under various conditions.

• An enhancement factor is defined to quantify thermophoretic coagulation in HTGRs.

• Thermophoretic coagulation becomes significant under large temperature gradients.

• The enhancement factor increased with decreased pressure and increased dust size.

Abstract

In high-temperature gas-cooled reactors, graphite dust particles within the reactor core and the heat transfer equipment experience large temperature gradients. Under such conditions, thermophoresis may play an important role in determining aerosol evolution. This study presents a theoretical and numerical analysis of the thermophoretic effects on aerosol coagulation within these reactors. The coagulation rates for Brownian versus thermophoretic coagulation are calculated and compared for various temperature gradients. Our results show that thermophoretic coagulation dominates over Brownian coagulation for large temperature gradients. We defined an enhancement factor to evaluate the role of thermophoretic coagulation under various reactor conditions. The enhancement factor increased dramatically with increasing temperature gradient, decreasing pressure and increasing particle diameter, but was not very sensitive to temperature change. The time evolution of the particle size distribution related to combined Brownian and thermophoretic coagulation was simulated using a log-skew-normal method of moments. The simulation results indicate that aerosol evolution can be strongly accelerated by thermophoretic coagulation under large temperature gradients.

Graphical abstract

Keywords

Graphite dust; High-temperature gas-cooled reactor; Thermophoretic coagulation; Log-skew-normal method of moments; Particle size distribution

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