Deposition Velocity and Penetration Efficiency in a Square Channel Using a Lagrangian-Based Modeling Approach

Abstract

Texas A&M University is working on the development of gas cooled fast reactor cartridge loop under the Department of Energy VTR program. Our research project aims to develop and implement techniques to quantify the transport and deposition of particle inside the cartridge loop. Before the developed techniques are applied in a complicated actual facility, it is essential to verify and validate their performance using numerical simulations and to quantify their uncertainties. This article presents a numerical study of particle transport and deposition in a proof-of-concept facility. The proof-of-concept facility houses a series of three square duct test sections, each of which has a cross-section of 3 in.2 and a length of 24 in., for a combined total length of 72 in. The numerical simulation domain is based on the geometrical dimensions of the experimental facility. The main stream in the channel is solved using the Eulerian turbulence model, and the particle motion is interpreted in the Lagrangian framework. It is assumed that a well-mixed air–particle mixture at a constant temperature is injected into the horizontal channel. Lagrangian simulations of surrogate particles allow us to understand their behavior precisely. The Reynolds stress model is selected to reproduce the secondary flow and the associated secondary drag force. The state-of-the-art Lagrangian approach, in combination with a random walk model coupled with a computational fluid dynamics model, is employed to investigate the behaviors of the surrogate particles within the square channel. Gravitational settling is also considered. The deposition velocity and penetration efficiency are estimated for representing the characteristics of particle deposition in the proof-of-concept facility. Because the conventional method of measuring the deposition velocity is based on the Eulerian framework, it is not suitable for direct adoption in the Lagrangian framework. This study proposes a numerical technique to measure the deposition velocity; this technique can be efficiently used in the Lagrangian framework of the simulation. The results agree well with both our experimental measurements and correlations available in the literature. Using this technique, the correlations for the deposition velocity are established as functions of the normalized channel length, Stokes number, and Reynolds number. Finally, the relationship between the deposition velocity and penetration efficiency is examined, and a correlation is proposed. Consequently, the penetration efficiency can be directly compared with several conventional reference data based on the deposition velocity.