Modeling radiation in particle clouds: on the importance of inter-particle radiation for pulverized solid fuel combustion

Haugen, Nils Erland L.; Mitchell, Reginald E.

doi:10.1007/s00231-014-1472-4

Cited by 6 publications

(9 citation statements)

References 11 publications

(18 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the particle were near the periphery of the cloud, its temperature would be somewhat lower than that for the base case because a significant portion of the radiant energy exchange would be between the particle and the cooler walls. A more detailed discussion of the importance of interparticle radiation for pulverized solid fuel combustion is provided in our previous work that focuses on this topic.…”

Section: Resultsmentioning

confidence: 99%

“…The energy conservation equation is expressed as follows: where T p , m p , and c p,p are the temperature, mass, and specific heat, respectively, of the particle. Expressions for Q rad can be found in our previous work . When Q reac is evaluated, the thermochemical data needed to calculate the heats of reaction of the heterogeneous reactions listed in Table were taken from the work of Tilghman and Mitchell. , An account is made for Stefan flow when determining the combined heat transfer coefficient between the particle and gas when evaluating Q con and for particle-to-wall radiation exchange as well as for particle-to-particle radiation exchange when evaluating Q rad .…”

Section: Theoretical Developmentmentioning

confidence: 99%

See 1 more Smart Citation

Comprehensive Char Particle Gasification Model Adequate for Entrained-Flow and Fluidized-Bed Gasifiers

2016

Self Cite

View full text Add to dashboard Cite

A robust, single-particle gasification model is presented that is capable of predicting char particle behavior in environments established in typical fluidized bed and entrained flow gasifiers. It employs a heterogeneous reaction mechanism that describes char reactivity to CO 2 , H 2 O and O 2 in the presence of H 2 and CO, gases that inhibit char reactivity. An effectiveness factor-Thiele modulus (η-φ) approach is used to determine overall conversion rates when species concentration gradients exist inside particles, which occur at high particle temperatures when chemical reaction rates and mass transport rates through particle pores become competitive. In the approach taken, a η-φ relation is determined for each reactive gas (CO 2 , H 2 O and O 2) and deviations from first-order behavior are correlated with the concentrations of the inhibitors (CO and H 2). A mean effectiveness factor is defined based on the individual species effectiveness factors and used in a mode of conversion model that governs the variations in particle size and apparent density during char conversion. In this paper, the pertinent model equations are presented, with focus on the effectiveness factor-Thiele moduli relations. The model is shown to be useful in identifying rate-limiting processes during char conversion in gaseous environments varying in temperature and composition. It serves as a tool that can be used to help design efficient coalfired and biomass-fired entrained flow and fluidized bed gasifiers as well as combustors.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Theoretical Developmentmentioning

confidence: 99%

Comprehensive Char Particle Gasification Model Adequate for Entrained-Flow and Fluidized-Bed Gasifiers

2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Heat transfer, mass transfer, and particle drag are calculated based on the representative particle diameter for each parcel, neglecting any agglomeration or grouping effects. It is essential to consider flow shielding, radiation shading, and other inter-particle effects to predict the particle heat up and the thermo-chemical conversion within particle clouds or dense particle jets correctly [7][8][9][10][11][12][13][14].…”

Section: Discussionmentioning

confidence: 99%

Dataset for the Heat-Up and Heat Transfer towards Single Particles and Synthetic Particle Clusters from Particle-Resolved CFD Simulations

Pichler

Bösenhofer

Harasek

2022

Data

View full text Add to dashboard Cite

Heat transfer to particles is a key aspect of thermo-chemical conversion of pulverized fuels. These fuels tend to agglomerate in some areas of turbulent flow and to form particle clusters. Heat transfer and drag of such clusters are significantly different from single-particle approximations commonly used in Euler–Lagrange models. This fact prompted a direct numerical investigation of the heat transfer and drag behavior of synthetic particle clusters consisting of 44 spheres of uniform diameter (60 μm). Particle-resolved computational fluid dynamic simulations were carried out to investigate the heat fluxes, the forces acting upon the particle cluster, and the heat-up times of particle clusters with multiple void fractions (0.477–0.999) and varying relative velocities (0.5–25 m/s). The integral heat fluxes and exact particle positions for each particle in the cluster, integral heat fluxes, and the total acting force, derived from steady-state simulations, are reported for 85 different cases. The heat-up times of individual particles and the particle clusters are provided for six cases (three cluster void fractions and two relative velocities each). Furthermore, the heat-up times of single particles with different commonly used representative particle diameters are presented. Depending on the case, the particle Reynolds number, the cluster void fraction, the Nusselt number, and the cluster drag coefficient are included in the secondary data.

show abstract

“…It is also ensured that the cooling of the particle considered equals the cooling that the average particle in a particle cloud would experience. When accounting for inter-particle radiation, and picking the average particle within the enclosure, the radiative term (Q rad ) can be expressed as [22]…”

Section: Particle Temperaturementioning

confidence: 99%

“…when β = aR ≪ 1. However, this is not the case in typical gasification reactors: inter-particle radiation should be taken into account when modeling the char gasification process [22].…”

Section: Particle Temperaturementioning

confidence: 99%

A comprehensive model for char particle conversion in environments containing O2 and CO2

Haugen

Mitchell

Tilghman

2015

Combustion and Flame

Self Cite

View full text Add to dashboard Cite

In this work, conversion of char is studied in a simulation code that includes a simplified heterogeneous adsorption-desorption reaction mechanism for char chemical reactivity and uses GRI-Mech 3.0 as the chemical kinetic mechanism that describes the impact of homogeneous reactions. Besides sub-models for the consequences of chemical reactions, a mode of char particle conversion sub-model is included that describes how particle size and apparent density vary with mass loss as well as a radiation sub-model that describes the radiant exchange of energy between the char particle and surrounding particles and walls. The code is transient and zero dimensional in space, and designed to be used both as a stand-alone gasification/combustion code and as a sub-model for heterogeneous reactions of solid particles in a CFD code.

show abstract

Modeling radiation in particle clouds: on the importance of inter-particle radiation for pulverized solid fuel combustion

Cited by 6 publications

References 11 publications

Comprehensive Char Particle Gasification Model Adequate for Entrained-Flow and Fluidized-Bed Gasifiers

Comprehensive Char Particle Gasification Model Adequate for Entrained-Flow and Fluidized-Bed Gasifiers

Dataset for the Heat-Up and Heat Transfer towards Single Particles and Synthetic Particle Clusters from Particle-Resolved CFD Simulations

A comprehensive model for char particle conversion in environments containing O2 and CO2

Contact Info

Product

Resources

About