Development and testing of a soot particle concentration estimator using Lagrangian post-processing

Abstract

Soot emissions from combustion devices are known to have harmful effects on the environment and human health. As the transportation industry continues to expand, the development of techniques to reduce soot emissions remains a significant goal of researchers and industry. In order for current soot modeling techniques to be reliably accurate, they must incur an intractably high computational cost. This project leverages existing knowledge in soot modeling and soot formation fundamentals to develop a stand-alone, computationally inexpensive soot concentration estimator to be linked to Computational Fluid Dynamics simulations as a post-processor. Preliminary development and testing of the estimator is presented here for laminar flames. As soot properties cannot be determined by local conditions, the estimator consists of a library generated using the hystereses of soot-containing fluid parcels, which relates soot concentration to the aggregated gas-phase environment histories to which a fluid parcel has been exposed. The estimator can be used to relate soot concentration to computed parcel hystereses through interpolation techniques. The estimator shows the potential ability to produce accurate results with very low computational cost in laminar coflow diffusion flames. Results also show that as flame data representing a broader set of conditions (temperature, mixture fraction, residence time, etc.) are added to the library, the estimator becomes applicable to a wider range of flames.

A novel soot concentration field estimator applied to sooting ethylene/air laminar flames

“…To address this problem, a novel solution has recently been proposed by Alexander, Bozorgzadeh, Khosousi, and Dworkin (2018), which leverages the knowledge from accurate soot modeling with detailed chemistry to estimate soot concentrations. This post-processing tool uses a library, built from Lagrangian hysteresis of key parameters that correlate soot formation from inception up to oxidation, to predict soot concentrations based on existing numerical Computational Fluid Dynamics (CFD) data.…”

“…It is important to state that this technique is not a model for soot formation and oxidation, but rather a framework which uses a library to estimate soot properties using correlations and interpolation (Alexander et al, 2018).…”

“…In Alexander et al (2018), the assessment of the soot estimator was carried out analyzing the soot volume fraction f v along two representative pathlines in coflow laminar diffusion flames, one at the centerline and the other passing through the point of maximum soot volume fraction, leaving the question of whether or not this technique could have broader applicability or if it can be applied to estimate the entire field of f v . Therefore, in the present study the estimator framework is extended to predict the entire field of f v in nine atmospheric laminar diffusion flames, and the accuracy of the prediction is analyzed and assessed.…”

“…The soot estimator is developed to aid combustion device designers in reducing soot emissions (Alexander et al, 2018). From experimental and validated numerical data available in the literature, a library is created to be used as a post-processing tool to predict soot concentrations based on existing numerical Computational Fluid Dynamics (CFD) data.…”

Study on the key structure parameters of a gravity settling chamber based on a flow field simulation

“…(2) The fluid dynamics equation of the particle phase Wu et al (2011), Winfield et al (2012Winfield et al ( , 2013aWinfield et al ( , 2013b, Wei (2016), Liu (2017) and Sun et al (2017b) applied the simulation method of the gas-solid two-phase flow to the flow field mixed with airflow and dust particles in the gravity settling chamber. And the Euler-Euler (E-E) method and Euler-Lagrange (E-L) method may be selected to solve the two-phase flow (Alexander, Bozorgzadeh, Khosousi, & Dworkin, 2018). The different phases are processed into the continuous mediums that penetrate each other in the E-E method.…”