Hierarchical calibration and validation of computational fluid dynamics models for solid sorbent-based carbon capture

Abstract

To quantify the predictive confidence of a device scale solid sorbent-based carbon capture design where there is no direct experimental data available, a hierarchical validation methodology is first proposed. In this hierarchy, a sequence of increasingly complex "unit problems" are validated using a statistical calibration framework. This paper describes the computational fluid dynamics (CFD) multi-phase reactive flow simulations and the associated data flows within each unit problem. Each validation requires both simulated and physical data, so the bench-top experiments used in each increasingly complex stage were carefully designed to follow the same operating conditions as the simulation scenarios. A Bayesian calibration procedure is employed and the posterior model parameter distributions obtained at one unitproblem level are used as prior distributions for the same parameters in the next-tier simulations.Overall, the results have demonstrated that the calibrated multiphase reactive flow models within MFIX can be used to capture the bed pressure, temperature, CO2 capture capacity, and kinetics © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 with quantitative accuracy. The CFD modeling methodology and associated uncertainty quantification techniques presented herein offer a solid framework for estimating the predictive confidence in the virtual scale up of a larger carbon capture device. KeywordsComputational fluid dynamics, carbon capture, hierarchical model validation methodology, multiphase reactive flow models, Bayesian calibration, MFIX.

Hierarchical calibration and validation for modeling bench‐scale solvent‐based carbon capture. Part 1: Non‐reactive physical mass transfer across the wetted wall column

“…From the computational perspective, accurate modeling of hydrodynamics and mass transfer in a WWC is the important first step in mimicking the real-world reactive multiphase flow interaction. [23][24][25][26] Lai et al 27 have implemented a Bayesian calibration procedure to estimate the predictive confidence of the CFD model for solid sorbent-based carbon capture. In addition, a one-fluid formula that accounts for both advection and diffusion 20 has been performed to simulate the gas phase mass transfer across the liquid film.…”

A Frequentist Approach to Computer Model Calibration

“…The experimental set‐up and the MFIX model that was used to simulate it are fully documented in Lai et al . (). Below, only an abridged description of the data is provided.…”

“…The allowable ranges of the model parameters were chosen to be the same as those devised in Lai et al . (), which are the physically plausible ranges of such parameters.…”

“…The open source computational fluid dynamics code MFIX, 'Multiphase flow with interphase exchanges' (Benyahia et al, 2012), was used as the simulator of the bubbling fluidized bed. The experimental set-up and the MFIX model that was used to simulate it are fully documented in Lai et al (2016). Below, only an abridged description of the data is provided.…”

“…The MFIX model parameters involved in the calibration for this case were Res-PP (θ 1 ), the particle-particle coefficient of restitution, Res-PW (θ 2 ), the particle-wall coefficient of restitution, FricAng-PP (θ 3 ), the particle-particle friction angle, FricAng-PW (θ 4 ), the particle-wall friction angle, PBVF (θ 5 ), the packed bed void fraction, and Part-Size (θ 6 ), the effective particle diameter of the sorbent material. The allowable ranges of the model parameters were chosen to be the same as those devised in Lai et al (2016), which are the physically plausible ranges of such parameters. Table 1 provides the estimated θ-values along with 95% confidence intervals and credible intervals respectively for the proposed fboot-rs method and the bss-anova method; both are numerically tested by simulations described in section S2 of the on-line supplemental document.…”