A Novel Modeling Approach for Plastics Melting within a CFD-DEM Framework

Celik, Alptekin; Bonten, Christian; Togni, Riccardo; Kloss, Christoph; Goniva, Christoph

doi:10.3390/polym13020227

Cited by 12 publications

(9 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, more recent research on extrusion modeling includes also the particle-resolved simulations in which progressive melting of particles is considered. As an example, Celik et al [201] considered the pellets as discretized particles in simulating single-screw extrusion. In this approach, each particle is considered as a sphere with a desired number of shells.…”

Section: Extrusion Modelsmentioning

confidence: 99%

“…The advantage of the phase-field model over the enthalpy-based model is that it is based on the crystal structure of the polymer and this provides the possibility of developing the model based on the plastic type more fundamentally, rather than using the enthalpy of solid and liquid phase, which are usually derived experimentally [201]. However, the challenge associated with the phase-field model is obtaining the free energy density function of the feedstock [205].…”

Section: Phase-field Modelsmentioning

confidence: 99%

See 1 more Smart Citation

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

et al. 2022

View full text Add to dashboard Cite

Among the different thermo-chemical recycling routes for plastic waste valorization, gasification is one of the most promising, converting plastic waste into syngas (H2+CO) and energy in the presence of an oxygen-rich gas. Plastic waste gasification is associated with many different complexities due to the multi-scale nature of the process, the feedstock complexity (mixed polyolefins with different contaminations), intricate reaction mechanisms, plastic properties (melting behavior and molecular weight distribution), and complex transport phenomena in a multi-phase flow system. Hence, creating a reliable model calls for an extensive understanding of the phenomena at all scales, and more advanced modeling approaches than those applied today are required. Indeed, modeling of plastic waste gasification (PWG) is still in its infancy today. Our review paper shows that the thermophysical properties are rarely properly defined. Challenges in this regard together with possible methodologies to decently define these properties have been elaborated. The complexities regarding the kinetic modeling of gasification are numerous, compared to, e.g., plastic waste pyrolysis, or coal and biomass gasification, which are elaborated in this work along with the possible solutions to overcome them. Moreover, transport limitations and phase transformations, which affect the apparent kinetics of the process, are not usually considered, while it is demonstrated in this review that they are crucial in the robust prediction of the outcome. Hence, possible approaches in implementing available models to consider these limitations are suggested. Finally, the reactor-scale phenomena of PWG, which are more intricate than the similar processes—due to the presence of molten plastic—are usually simplified to the gas-solid systems, which can result in unreliable modeling frameworks. In this regard, an opportunity lies in the increased computational power that helps improve the model’s precision and allows us to include those complexities within the multi-scale PWG modeling. Using the more accurate modeling methodologies in combination with multi-scale modeling approaches will, in a decade, allow us to perform a rigorous optimization of the PWG process, improve existing and develop new gasifiers, and avoid fouling issues caused by tar.

show abstract

Section: Extrusion Modelsmentioning

confidence: 99%

Section: Phase-field Modelsmentioning

confidence: 99%

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Instead, it is discretized into interacting particle ensembles (two-dimensional disk (2D) and three-dimensional sphere (3D) are the main particle shape in space) by constructing particle ensembles into specimens of different geometries, utilizing a contact model forming interactions and iterative analysis based on Newton’s second law to make the macroscopic mechanical properties of the numerical specimen approach those of real materials [ 25 ]. Therefore, with the DEM method, the problems of discontinuities, high gradient variables, and remeshing in fracture or damage can be overcome [ 26 , 27 , 28 , 29 ]. The DEM method has been widely used to describe the macroscopic mechanical properties of materials, such as rock [ 30 , 31 ], soil [ 32 ], and concrete [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Compression-Softening Bond Model for Non-Water Reactive Foaming Polyurethane Grouting Material

Dong

Fang

et al. 2023

Polymers

View full text Add to dashboard Cite

In this study, the uniaxial compression and cyclic loading and unloading experiments were conducted on the non-water reactive foaming polyurethane (NRFP) grouting material with a density of 0.29 g/cm3, and the microstructure was characterized using scanning electron microscope (SEM) method. Based on the uniaxial compression and SEM characterization results and the elastic-brittle-plastic assumption, a compression softening bond (CSB) model describing the mechanical behavior of micro-foam walls under compression was proposed, and it was assigned to the particle units in a particle flow code (PFC) model simulating the NRFP sample. Results show that the NRFP grouting materials are porous mediums consisting of numerous micro-foams, and with the increasing density, the diameter of the micro-foams increases and the micro-foam walls become thicker. Under compression, the micro-foam walls crack, and the cracks are mainly perpendicular to the loading direction. The compressive stress–strain curve of the NRFP sample contains the linear increasing stage, yielding stage, yield plateau stage, and strain hardening stage, and the compressive strength and elastic modulus are 5.72 MPa and 83.2 MPa, respectively. Under the cyclic loading and unloading, when the number of cycles increases, the residual strain increases, and there is little difference between the modulus during the loading and unloading processes. The stress–strain curves of the PFC model under uniaxial compression and cyclic loading and unloading are consistent with the experimental ones, well indicating the feasibility of using the CSB model and PFC simulation method to study the mechanical properties of NRFP grouting materials. The failure of the contact elements in the simulation model causes the yielding of the sample. The yield deformation propagates almost perpendicular to the loading direction and is distributed in the material layer by layer, which ultimately results in the bulging deformation of the sample. This paper provides a new insight into the application of the discrete element numerical method in NRFP grouting materials.

show abstract

“…Previous models begin by assuming a melting mechanism, other authors have proposed to solve the general balance equations of continuity, momentum, and energy with an adequate constitutive equation using numerical methods. Mathematical and numerical models using the Finite Elements Method (FEM), Finite Volumes Method (FVM), and Discrete Elements Method (DEM) have been reported by Viriyayuthakorn and Kassahun, [ 40 ] Syrjala, [ 41 ] Altinkaynak et al, [ 42 ] Hopmann et al, [ 43 ] Lewandowski and Wilczynski, [ 44 ] Celik et al, [ 45 ] among others. Up to this point, the discussed analytical and computational models, as well as most of the remaining models presented by Wilczynski et al in their paper review, do not explain the process or describe the melting mechanism in GPEs.…”

Section: Introductionmentioning

confidence: 99%

A novel melting model for polymer extrusion: Mechanically induced transition layer removal

Estrada

Janna

2022

Polymer Engineering & Sci

View full text Add to dashboard Cite

A novel polymer melting mechanism and model named mechanically induced transition layer removal is introduced as the most probable hypothesis to explain the enhanced behavior in terms of melting capacity, output, and energy efficiency of single screw Grooved Plasticating Extruders (GPE). This model considers a domain conformed by three phases: solid, molten or plasticized, and transition layers; the latter has never been considered in the state of the art before. To validate this hypothesis as the first approach, we present a simplified thermodynamic polymer melting model in drag and pressureinduced flow between parallel plates. The model is solved using the Finite Difference Method (FDM). The results obtained show that the proposed model enables a considerable improvement in the plasticizing speed. In addition, this mechanism describes the phenomenology of the plasticization process in the GPE presented in the state of the art. In future works, the mechanically induced transition layer removal, extended to the geometry and operating conditions in GPE, has the potential to accurately describe how this type of technology operates and help the improvement and design of new plasticizing units.

show abstract

A Novel Modeling Approach for Plastics Melting within a CFD-DEM Framework

Cited by 12 publications

References 39 publications

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

Multi-Scale Modeling of Plastic Waste Gasification: Opportunities and Challenges

Compression-Softening Bond Model for Non-Water Reactive Foaming Polyurethane Grouting Material

A novel melting model for polymer extrusion: Mechanically induced transition layer removal

Contact Info

Product

Resources

About