Detailed knowledge of solids circulation, bubble motion, and frequencies of porosity oscillations is needed for a better understanding of tube erosion in fluidized bed combustors. A predictive two-phase flow model was derived starting with the Boltzman equation for velocity distribution of particles. The model is a generalization of the Navier-Stokes equations of the type proposed by R. Jackson, except that the solids viscosities and stresses are computed by simultaneously solving a fluctuating energy equation for the particulate phase. The model predictions agree with time-averaged and instantaneous porosities measured in two-dimensional fluidized beds. Observed flow patterns and bubbles were also predicted.

A bubbling fluidization model using kinetic theory of granular flow

This report describes the MFIX (Multiphase Flow with Interphase exchanges) computer model. MFIX is a general-purpose hydrodynamic model that describes chemical reactions and heat transfer in dense or dilute fluid-solids flows, flows typically occurring in energy conversion and chemical processing reactors. MFIX calculations give detailed information on pressure, temperature, composition, and velocity distributions in the reactors. With such information, the engineer can visualize the conditions in the reactor, conduct parametric studies and what-if experiments, and, thereby, assist in the design process. The MFIX model, developed at the Morgantown Energy Technology Center (METC), has the following capabilities: mass and momentum balance equations for gas and multiple solids phases; a gas phase and two solids phase energy equations; an arbitrary number of species balance equations for each of the phases; granular stress equations based on kinetic theory and frictional flow theory; a user-defined chemistry subroutine; three-dimensional Cartesian or cylindrical coordinate systems; nonuniform mesh size; impermeable and semi-permeable internal surfaces; user-friendly input data file; multiple, single-precision, binary, direct-access, output files that minimize disk storage and accelerate data retrieval; and extensive error reporting. This report, which is Volume 1 of the code documentation, describes the hydrodynamic theory used in the model: the conservation equations,more » constitutive relations, and the initial and boundary conditions. The literature on the hydrodynamic theory is briefly surveyed, and the bases for the different parts of the model are highlighted.« less

/pdf/mfix-documentation-theory-guide-3zhuwh0yn7.pdf

MFIX documentation theory guide

https://discovery.ucl.ac.uk/1461360/1/dodds_et_al_(2015)_h2fc_heating_review__ijhe.pdf

Hydrogen and fuel cell technologies for heating: A review

https://escholarship.org/content/qt7p3500g2/qt7p3500g2.pdf

Determining the lowest-cost hydrogen delivery mode

Hydrodynamics of gas-solid fluidization

The hydrodynamics of fluidization for two thin ''two-dimensional'' fluidized beds, one containing a centrally located rectangular obstacle and the other containing three square tubes roughly approximating a portion of a fluidized bed combustor (FBC), was solved using the FLUFIX/MOD2 computer program. The monolayer energy dissipation erosion model extended to include solids viscous stress was compared with the Finnie erosion model. Hydrodynamic and erosion convergence studies were performed for the first bed. Computed erosion rates from the monolayer energy dissipation erosion model compare more favorably for both beds with available erosion data than those from the Finnie erosion model. 27 refs., 15 figs.

Hydrodynamics of erosion of heat exchanger tubes in fluidized bed combustors

Hydrogen: On the Horizon or Just a Mirage?

To promote the resilience and protection of infrastructure assets from an all-hazards perspective, this paper describes the progress of interdependencies modeling and integration efforts to...

https://ascelibrary.org/doi/pdf/10.1061/%28ASCE%29IS.1943-555X.0000395

Modeling Electric Power and Natural Gas System Interdependencies

Modeling Electric Power and Natural Gas Systems Interdependencies

Whether produced from fossil or non‐fossil sources, the widespread use of hydrogen will require a new and extensive infrastructure to produce, distribute, store and dispense it as a vehicular fuel or for electric generation. Depending on the source from which hydrogen is produced and the form in which it is delivered, many alternative infrastructures can be envisioned. Tradeoffs in scale economies between process and distribution technologies, and such issues as operating cost, safety, materials, etc. can also favor alternative forms of infrastructure. This paper discusses several infrastructure alternatives and the associated “well‐to‐pump” or “fuel cycle” cost of delivered hydrogen.

Stephen M. Folga

Papers

Hydrodynamics of erosion of heat exchanger tubes in fluidized bed combustors

Hydrogen: On the Horizon or Just a Mirage?

Modeling Electric Power and Natural Gas System Interdependencies

Modeling Electric Power and Natural Gas Systems Interdependencies

Hydrogen Distribution Infrastructure