Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing

Sprague, Michael A.; Stickel, Jonathan J.; Sitaraman, Hariswaran; Crawford, Nathan

doi:10.1016/j.ces.2018.02.030

Title: Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing

Abstract

In this paper we develop a computational model for the mixing and transport of a dilute biomass slurry. The objective was to create a sufficiently simple and efficient model for biomass transport that can be coupled with reaction models for the study of conversion of cellulosic biomass into fermentable sugars. Our target system is 5%-by-mass ..alpha..-cellulose, which is our proxy for more complex lignocellulosic biomass. In the authors' previous work, an experimental investigation with ..alpha..-cellulose under two vane-mixer configurations showed a bifurcation between a settling regime, for which settling effects dominate, and a suspended regime, for which solids are mostly suspended. Here, a mixed-fluid model was chosen, for which the model for the mixture-velocity field is the incompressible Navier-Stokes equations under the Boussinesq approximation for buoyancy. Solids transport includes solids motion due to diffusion, settling, advection, and shear. Comparison of simulated and experimental results show good agreement in the suspended regime, and in capturing the bifurcation rate. While the model captured well the distribution of solids in the settling regime, the model was incapable of capturing the high torque values seen in experiments with vanishing mixer rotation rate.

Authors:

Sprague, Michael A. ^[1]; Stickel, Jonathan J. ^[1]; Sitaraman, Hariswaran ^[1]; Crawford, Nathan ^[1]

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:: 2018-02-17

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Bioenergy Technologies Office

OSTI Identifier:: 1427349

Alternate Identifier(s):: OSTI ID: 1548687

Report Number(s):: NREL/JA-5000-70621
Journal ID: ISSN 0009-2509; TRN: US1802584

Grant/Contract Number:: AC36-08GO28308; AC36-08-GO28308

Resource Type:: Accepted Manuscript

Journal Name:: Chemical Engineering Science

Additional Journal Information:: Journal Volume: 182; Journal Issue: C; Journal ID: ISSN 0009-2509

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 09 BIOMASS FUELS; multi-phase flow; sedimentation; spectral finite elements; high-order methods

Citation Formats


                    Sprague, Michael A., Stickel, Jonathan J., Sitaraman, Hariswaran, and Crawford, Nathan. Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing.  United States: N. p., 2018. 
Web.  doi:10.1016/j.ces.2018.02.030.

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                    Sprague, Michael A., Stickel, Jonathan J., Sitaraman, Hariswaran, & Crawford, Nathan. Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing.  United States.  https://doi.org/10.1016/j.ces.2018.02.030

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                    Sprague, Michael A., Stickel, Jonathan J., Sitaraman, Hariswaran, and Crawford, Nathan. Sat .  
"Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing".  United States.  https://doi.org/10.1016/j.ces.2018.02.030.  https://www.osti.gov/servlets/purl/1427349.

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@article{osti_1427349,

  title        = {Formulation and validation of a computational model for a dilute biomass slurry undergoing rotational mixing},

  author       = {Sprague, Michael A. and Stickel, Jonathan J. and Sitaraman, Hariswaran and Crawford, Nathan},

  abstractNote = {In this paper we develop a computational model for the mixing and transport of a dilute biomass slurry. The objective was to create a sufficiently simple and efficient model for biomass transport that can be coupled with reaction models for the study of conversion of cellulosic biomass into fermentable sugars. Our target system is 5%-by-mass ..alpha..-cellulose, which is our proxy for more complex lignocellulosic biomass. In the authors' previous work, an experimental investigation with ..alpha..-cellulose under two vane-mixer configurations showed a bifurcation between a settling regime, for which settling effects dominate, and a suspended regime, for which solids are mostly suspended. Here, a mixed-fluid model was chosen, for which the model for the mixture-velocity field is the incompressible Navier-Stokes equations under the Boussinesq approximation for buoyancy. Solids transport includes solids motion due to diffusion, settling, advection, and shear. Comparison of simulated and experimental results show good agreement in the suspended regime, and in capturing the bifurcation rate. While the model captured well the distribution of solids in the settling regime, the model was incapable of capturing the high torque values seen in experiments with vanishing mixer rotation rate.},

  doi          = {10.1016/j.ces.2018.02.030},

  journal      = {Chemical Engineering Science},

  number       = C,

  volume       = 182,

  place        = {United States},

  year         = {2018},

  month        = {2}

}

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Cited by: 2 works

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Figure 1: (a) Profile and (b) bottom view of the four-blade vane rotor. (c) Vane-in-cup and (d) vane-in-beaker experimental setups. The 5%-by-mass $α$-cellulose slurry is in the fully settled state in image (d). Dimensions of the vane are depicted in image (e) in mm.

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