A Numerical Model of Biomass Combustion Physical and Chemical Processes

Identifying a modeling procedure of biomass thermal decomposition that is not only simple enough to implement and use, and computationally efficient, but also sufficiently accurate for engineering design activities, and with a spectrum of applications as broad as possible is a very difficult task. The authors propose a procedure which consists of two main stages: (a) the static modeling phase with the purpose of generating the algorithm (macro functions) that supplies a Computational Fluid Dynamics (CFD) model with specific input data (source/sink terms and local material properties) and (b) the dynamic modeling phase, where the CFD model is bi-directionally coupled to the external biomass decomposition model in the form of a User-Defined Function (UDF). The modeling approach was successfully validated against data obtained from single particle decomposition experiments, demonstrating its applicability even to large biomass particles, under high heating rates and combusting conditions.

Download Full-text

Validation of a Computationally Efficient Computational Fluid Dynamics (CFD) Model for Industrial Bubble Column Bioreactors

Industrial & Engineering Chemistry Research ◽

10.1021/ie501105m ◽

2014 ◽

Vol 53 (37) ◽

pp. 14526-14543 ◽

Cited By ~ 31

Author(s):

Dale D. McClure ◽

Hannah Norris ◽

John M. Kavanagh ◽

David F. Fletcher ◽

Geoffrey W. Barton

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Bubble Column ◽

Cfd Model ◽

Computationally Efficient ◽

Computational Fluid Dynamics Cfd

Download Full-text

Bending tests on GLT beams having well-known local material properties

Materials and Structures ◽

10.1617/s11527-014-0424-2 ◽

2014 ◽

Vol 48 (11) ◽

pp. 3571-3584 ◽

Cited By ~ 9

Author(s):

Gerhard Fink ◽

Andrea Frangi ◽

Jochen Kohler

Keyword(s):

Material Properties ◽

Bending Tests ◽

Local Material ◽

Local Material Properties

Download Full-text

Consideration of Parameter Scattering in Thermo-Mechanical Characterization of Advanced Packages

Journal of Electronic Packaging ◽

10.1115/1.2793853 ◽

1999 ◽

Vol 121 (4) ◽

pp. 282-285 ◽

Cited By ~ 1

Author(s):

T. Winkler ◽

A. Schubert ◽

E. Kaulfersch ◽

B. Michel

Keyword(s):

Finite Element ◽

Life Time ◽

Electronic Packages ◽

Element Determination ◽

Local Material ◽

Element Simulation ◽

Geometrical Imperfections ◽

Element Approach ◽

Partial Randomness ◽

Local Material Properties

Much progress has been made in the simulation and verification of the thermo-mechanical behavior of plastic packages. On the other hand, until now there is a lack in the consideration of the scatter or uncertainty, respectively, of certain characteristics. A comparatively large scatter of local material properties or random geometrical imperfections can often be observed within the material compounds of electronic packages. The partial randomness of certain input parameters creates uncertainties in the finite element determination of mechanical quantities which are provided for thermo-mechanical reliability optimization and life time prediction. In the following the STOFEM stochastic finite element approach based on perturbation theory is applied as a part of the finite element simulation. It is used to find out some additional effects arising from uncertainties in the modeling, slightly varying parameters or probabilistic influences, respectively. In a second part of the paper, another approach to the consideration of random variations is discussed. It is based on the randomization of initially deterministic relations.

Download Full-text

A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

Volume 5: High-Pressure Technology; ASME Nondestructive Evaluation, Diagnosis and Prognosis Division (NDPD); Rudy Scavuzzo Student Paper Symposium and 26th Annual Student Paper Competition ◽

10.1115/pvp2018-84591 ◽

2018 ◽

Author(s):

Feng Jie Zheng ◽

Fu Zheng Qu ◽

Xue Guan Song

Keyword(s):

Pressure Fluctuation ◽

Large Scale ◽

Three Dimensional ◽

Industrial Process ◽

Multiscale Model ◽

Computational Time ◽

Small Scale ◽

Cfd Model ◽

Computationally Efficient ◽

Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial process. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operation such as rapid valve opening/closing. To investigate the pressure especially the pressure fluctuation in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled by a zero-dimensional virtual point, the pipe is modeled by a one-dimensional MOC, and the valve is modeled by a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted, in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve are obtained. The results show that the proposed model is in good agreement with the full CFD model in both large-scale and small-scale spaces. Moreover, the proposed model is more computationally efficient than the CFD model, which provides a feasibility in the analysis of complex RPV system within an affordable computational time.

Download Full-text

A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

Journal of Pressure Vessel Technology ◽

10.1115/1.4044117 ◽

2019 ◽

Vol 141 (5) ◽

Author(s):

Feng Jie Zheng ◽

Chao Yong Zong ◽

William Dempster ◽

Fu Zheng Qu ◽

Xue Guan Song

Keyword(s):

Large Scale ◽

Pressure Fluctuations ◽

Three Dimensional ◽

Multiscale Model ◽

Computational Time ◽

Small Scale ◽

Dimensional System ◽

Cfd Model ◽

Computationally Efficient ◽

Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial processes. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operations such as rapid valve opening or closing. To investigate the pressure response, with particular interest in the pressure fluctuations in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled as a zero-dimensional virtual point, the pipe is modeled as a one-dimensional system using the MOC, and the valve is modeled using a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve is obtained. The results show that the proposed model is in good agreement when compared with a high fidelity CFD model used to represent both large-scale and small-scale spaces. As expected, the proposed model is significantly more computationally efficient than the CFD model. This demonstrates the feasibility of analyzing complex RPV systems within an affordable computational time.

Download Full-text

Effects of heating rate and heating up time to central biomass particles for bio-oil production

Bangladesh Journal of Scientific and Industrial Research ◽

10.3329/bjsir.v51i1.27031 ◽

2016 ◽

Vol 51 (1) ◽

pp. 13-22

Author(s):

MB Ahmed ◽

ATMK Hasan ◽

M Mohiuddin ◽

M Asadullah ◽

MS Rahman ◽

...

Keyword(s):

Heating Rate ◽

Particle Temperature ◽

Product Distribution ◽

Heating Rates ◽

Final Temperature ◽

Central Mass ◽

Bio Oil ◽

Reactor Temperature ◽

Biomass Particles ◽

Heating Up

Objective of this work was to pyrolysis woody biomass. Experiments were carried out at 300 to 500oC. Relatively bigger particles were used. Special emphasis was given to investigate the effects of heating rate and heating up time of the central mass of the particles on the product distribution. Surface temperature reached to the reactor set temperature immediately while the temperature at the central part was as low as 50oC. The center temperature gradually increased to the final temperature within 3 to 8 minutes, depending on the wood types and the reactor set temperature. For ipil-ipil wood the heating rate of the central mass was much faster than krishnachura and koroi woods, and thus the heating up time was lower. Ipil-ipil wood was experienced higher yield (65%) even at lower reactor temperature 300oC with particle temperature 450oC. In the case of krishnachura and koroi woods, the bio-oil yields were lower under the same condition due to the heating rates of the central parts were much slower. Further researchon different biomasses may be necessary to demonstrate overall process.Bangladesh J. Sci. Ind. Res. 51(1), 13-22, 2016

Download Full-text

A Mathematical Model of Biomass Combustion Physical and Chemical Processes

Energies ◽

10.3390/en13236232 ◽

2020 ◽

Vol 13 (23) ◽

pp. 6232

Author(s):

Florin Popescu ◽

Razvan Mahu ◽

Ion V. Ion ◽

Eugen Rusu

Keyword(s):

Heat Transfer ◽

Mathematical Model ◽

Chemical Composition ◽

Material Properties ◽

Biomass Combustion ◽

Combustion Model ◽

Decomposition Model ◽

Volatile Products ◽

Local Material Properties ◽

Biomass Decomposition

The numerical simulation of biomass combustion requires a model that must contain, on one hand, sub-models for biomass conversion to primary products, which involves calculations for heat transfer, biomass decomposition rate, product fractions, chemical composition, and material properties, and on the other hand, sub-models for volatile products transport inside and outside of the biomass particle, their combustion, and the char reduction/oxidation. Creating such a complete mathematical model is particularly challenging; therefore, the present study proposes a versatile alternative—an originally formulated generalized 3D biomass decomposition model designed to be efficiently integrated with existing CFD technology. The biomass decomposition model provides the chemical composition and mixture fractions of volatile products and char at the cell level, while the heat transfer, species transport, and chemical reaction calculations are to be handled by the CFD software. The combustion model has two separate units: the static modeling that produces a macro function returning source/sink terms and local material properties, and the dynamic modeling that tightly couples the first unit output with the CFD environment independently of the initial biomass composition, using main component fractions as initial data. This article introduces the generalized 3D biomass decomposition model formulation and some aspects related to the CFD framework implementation, while the numerical modeling and testing shall be presented in a second article.

Download Full-text

Characterizing the Local Material Properties of Different Fe–C–Cr-Steels by Using Deep Rolled Single Tracks

Materials ◽

10.3390/ma13214987 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4987

Author(s):

Nicole Wielki ◽

Noémie Heinz ◽

Daniel Meyer

Keyword(s):

Deep Rolling ◽

Track Geometry ◽

Material Development ◽

State Dependent ◽

Local Material ◽

Material State ◽

Aisi 1045 ◽

Cr System ◽

Machining Operations ◽

Local Material Properties

As part of a novel method for material development, deep rolling was used in this work to characterize the mechanical properties of macroscopic specimens of C45 (AISI 1045), S235 (AISI 1015), and 100Cr6 (AISI 52100) in various heat treatment states. Deep rolling is conventionally used to enhance surface and subsurface properties by reducing the surface roughness, introducing compressive residual stresses, and strain hardening. In the context of this work, it was utilized to determine material-specific variables via a mechanically applied load. For that purpose, the geometries of individual deep rolled tracks were measured. In dependence of the process parameters such as deep rolling pressure and tool size, the track geometry, i.e., the specific track depth, was for the first time compared for different materials. A functional relationship identified between the specific track depth and the material state dependent hardness forms the basis for a future characterization of the properties of alloy compositions belonging to the Fe–C–Cr system. Since deep rolling is performed in the same clamping as machining operations, hardness alterations could easily be determined at different points in the process chain using an optical in-process measurement of track geometries in the future.

Download Full-text