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See detailDRYING AND CONVERSION ANALYSIS OF BIOMASS BY A DEM-CFD COUPLING APPROACH
Mohseni, Seyedmohammad UL

Doctoral thesis (2017)

Biomass materials as a type of renewable energy sources have attracted many attention nowadays to decrease fossil fuel usage due to ecological and economical benefits. The main objective of this PhD ... [more ▼]

Biomass materials as a type of renewable energy sources have attracted many attention nowadays to decrease fossil fuel usage due to ecological and economical benefits. The main objective of this PhD thesis is studying the drying and conversion of biomass materials with employing a hybrid four-way DEM-CFD coupling approach in which considers the solid particulates as discrete elements coupled via heat, mass and momentum transfer to the surrounding gas as continuous phase. Where a comprehensive three-dimensional numerical model is developed and applied to investigate the complex phenomena taking place during biomass drying and conversion in a reactor. That is referred to take into account the physical and chemical processes as heat-up, drying, pyrolysis, gasification and combustion including the essential heterogeneous and homogeneous reactions which is considered as an interactive solid-gas multiphase system. In the proposed model, the motion and thermodynamic state of the particles are involved with employing the relevant governing equations. Where the conductive and radiative heat transfer between particles as well as convective heat transfer between particles and gas phase are taken into account. In addition, some interfaces are extended for coupling the solid particles and the gas phase to consider the interactions in between. At first, the importance of biomass resources is discussed and then the mathematical modeling employed in the PhD thesis is explained thoroughly. To apply the model, four different cases are assessed where two chapters discuss the drying behavior of biomass particles in two different situations. Afterwards, the motion of solid particles in a bubbling fluidized bed is examined. Finally, the conversion of wood materials in a bubbling fluidized bed is determined. [less ▲]

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See detailEffects of particle size distribution on drying characteristics in a drum by XDEM: A case study
Mohseni, Seyedmohammad UL

in Chemical Engineering Science (2016), 152

The objective of this study is analysis of drying process of wet woody particles in a circulating cylinder including dynamics investigation of moving particles by eXtended Discrete Element Method (XDEM ... [more ▼]

The objective of this study is analysis of drying process of wet woody particles in a circulating cylinder including dynamics investigation of moving particles by eXtended Discrete Element Method (XDEM). In this approach, the particles are resolved as discrete phase coupled via heat, mass and momentum transfer to the surrounding gas phase. The drying of a spherical single particle is validated with experiments for different particle diameter and the temperature behavior during drying is investigated in addition to the moisture content and drying rate of the particle so that the comparisons show a good agreement meaning XDEM is a reliable tool to simulate drying process. The test case is a cylinder rotating with a constant angular velocity including a bed of moist wood particles. The main focus of this work is evaluating the effect of particle size distribution on drying rate and heat loss in the system. Furthermore, the influence of the inlet gas temperature and velocity on the particle bed mean temperature and moisture content is investigated. Eventually, the surface temperature distribution of particles in different instances during drying is visually demonstrated and the behavior of surface area on residence time is discussed. [less ▲]

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See detailA discrete/continuous numerical approach to multi-physics
Peters, Bernhard UL; Besseron, Xavier UL; Estupinan Donoso, Alvaro Antonio UL et al

in IFAC-PapersOnLine (2015), 28(1), 645-650

A variety of technical applications are not only the physics of a single domain, but include several physical phenomena, and therefore are referred to as multi-physics. As long as the phenomena being ... [more ▼]

A variety of technical applications are not only the physics of a single domain, but include several physical phenomena, and therefore are referred to as multi-physics. As long as the phenomena being taken into account is either continuous or discrete i.e. Euler or Lagrangian a homogeneous solution concept can be employed. However, numerous challenges in engineering include continuous and discrete phase simultaneously, and therefore cannot be solved only by continuous or discrete approaches. Problems include both a continuous and a discrete phase are important in applications of the pharmaceutical Industry e.g. drug production, agriculture and food processing industry, mining, construction and Agricultural machinery, metal production, power generation and systems biology. The Extended Discrete Element Method (XDEM) is a novel technique, which provides a significant advance for the coupled discrete and continuous numerical simulation concepts. It expands the dynamics of particles as described by the classical discrete element method (DEM) by a thermodynamic state or stress/strain coupled as fluid flow or structures for each particle in a continuum phase. XDEM additionally estimates properties such as the interior temperature and/or species distribution. These predictive capabilities are extended to fluid flow through an interaction by heat, mass and momentum transfer important for process engineering. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 37 (3 UL)