scholarly journals Modelling of Mass Transfer Resistances in Non-uniformly Washcoated Monolith Reactors

2021 ◽  
Author(s):  
M. Walander ◽  
J. Sjöblom ◽  
D. Creaser ◽  
B. Agri ◽  
N. Löfgren ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Elevated Temperatures ◽  
Effective Diffusivity ◽  
Gravimetric Analysis ◽  
New Model ◽  
Modelling Framework ◽  
Local Material ◽  
Monolith Reactors ◽  
1D Model ◽  
Local Material Properties

AbstractThere are various methodologies to account for mass transfer within non-uniformly distributed washcoats in monolith reactors in 1D models (axially). However, 1+1D models (axially/radially) fail to capture local variations in mass transfer from different coating thicknesses or cracks. In this paper, we present a novel way to account for local material properties in a washcoated monolith reactor. The suggested method uses an existing 1+1D modelling framework and sectionalizes the washcoat into multiple tangential segments which are solved independently. Intelligent gravimetric analysis and scanning electron microscopy are used in combination to calculate local effective diffusivity as an input for each simulation. The new model is compared to the original 1+1D model using NO light-off simulations. The new model predicted increased conversion at elevated temperatures, where mass transfer limitations are present, due to the higher porosity in the corners. The simulation time for each model was similar due to the parallelizable nature of the new model.

scholarly journals A Short-Time Approach for Fatigue Life Evaluation of AISI 347 Steel for Nuclear Power Energy Applications

2021 ◽  
Vol 11 (23) ◽  
pp. 11405
Author(s):  
Tobias Bill ◽  
Ruth Acosta ◽  
Christian Boller ◽  
Kai Donnerbauer ◽  
Lukas Lücker ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Elevated Temperatures ◽  
Cost Effective ◽  
Fatigue Tests ◽  
Destructive Testing ◽  
Energy Applications ◽  
Local Material ◽  
Short Time ◽  
Local Material Properties ◽  
Non Destructive

AISI 347 austenitic steel is, as an example, used in nuclear energy piping systems. Piping filled with superheated steam or cooled water is particularly exposed to high stresses, whereupon local material properties in the pipes can change significantly, especially in the case of additional corrosive influences, leading to aging of the material. In the absence of appropriate information, such local material property variations are currently covered rather blanketly by safety factors set during the design of those components. An increase in qualified information could improve the assessment of the condition of such aged components. As part of the collaborative project “Microstructure-based assessment of the maximum service life of core materials and components subjected to corrosion and fatigue (MiBaLeB)”, the short-time procedure, StrainLife, was developed and validated by several fatigue tests. With this procedure, a complete S–N curve of a material can be determined on the basis of three fatigue tests only, which reduces the effort compared to a conventional approach significantly and is thus ideal for assessing the condition of aged material, where the material is often rare, and a cost-effective answer is often very needed. The procedure described is not just limited to traditional parameters, such as stress and strain, considered in destructive testing but rather extends into parameters derived from non-destructive testing, which may allow further insight into what may be happening within a material’s microstructure. To evaluate the non-destructive quantities measured within the StrainLife procedure and to correlate them with the aging process in a material, several fatigue tests were performed on unnotched and notched specimens under cyclic loading at room and elevated temperatures, as well as under various media conditions, such as distilled water and reactor pressure vessel boiling water (BWR) conditions.

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

2014 ◽  
Vol 48 (11) ◽  
pp. 3571-3584 ◽  
Author(s):  
Gerhard Fink ◽  
Andrea Frangi ◽  
Jochen Kohler
Keyword(s):  
Material Properties ◽  
Bending Tests ◽  
Local Material ◽  
Local Material Properties

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

1999 ◽  
Vol 121 (4) ◽  
pp. 282-285 ◽  
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.

Mass transfer characteristics of three-phase monolith reactors

2001 ◽  
Vol 56 (21-22) ◽  
pp. 6015-6023 ◽  
Author(s):  
Michiel T. Kreutzer ◽  
Peng Du ◽  
Johan J. Heiszwolf ◽  
Freek Kapteijn ◽  
Jacob A. Moulijn
Keyword(s):  
Mass Transfer ◽  
Transfer Characteristics ◽  
Three Phase ◽  
Monolith Reactors

scholarly journals Role of Copper Oxide on Epoxy Coatings with New Intumescent Polymer-Based Fire Retardant

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5978
Author(s):  
Riyazuddin ◽  
Samrin Bano ◽  
Fohad Mabood Husain ◽  
Jamal Akhter Siddique ◽  
Khadijah H. Alharbi ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Heat Release ◽  
Flame Retardant ◽  
Cone Calorimeter ◽  
Elevated Temperatures ◽  
Fire Retardant ◽  
Intumescent Flame Retardant ◽  
Gravimetric Analysis ◽  
Sem Images ◽  
Major Drawback

Epoxy resins (EP) have been used as a thermos-setting material in the field of coating, casting, bonding agent, and laminating. However, a major drawback associated with its use is the lack of good flaming properties, and it is responsible for heavy smoke along with hazardous gases considerably limiting its uses in various fields. In this study, N-ethanolamine triazine-piperizine, a melamine polymer (ETPMP), was established as a new charring-foaming agent and was successfully synthesized with ethanolamine, piperizine, cyanuric chloride, and melamine as precursor molecules via the nucleophilic substitution reaction method. Elemental analysis and Fourier transform infrared (FTIR) spectroscopy analysis were applied to approve the synthesis of ETPMP and confirmation of its structure and characterization. The epoxy coating of intumescent flame retardant (IFR) was equipped by introducing ETPMP, ammonium polyphosphate (APP), and copper oxide (CuO) in multiple composition ratios. CuO was loaded at various amounts into the IFR-coating system as a synergistic agent. The synergistic action of CuO on IFR coatings was scientifically examined by using different analytical tests such as vertical burning test (UL-94V), limited oxygen index (LOI), thermal gravimetric analysis (TGA), cone calorimeter, and scanning electron microscope (SEM). The results showed that small changes in the amount of CuO expressively amplified the LOI results and enhanced the V-0 ratings in the UL-94V test. The TGA data clearly demonstrate that the inclusion of CuO can transform the thermal deprivation behavior of coatings with a growing char slag proportion with elevated temperatures. Information from cone calorimeter data affirmed that CuO can decrease the burning factors by total heat release (THR) together with peak heat release rate (PHRR). The SEM images indicated that CuO can enrich the power and compression of the intumescent char that restricts the movement of heat and oxygen. Our results demonstrate a positive influence of CuO on the epoxy-headed intumescent flame retardant coatings.

scholarly journals Problematic issues of geographical education in Kazakhstan

2020 ◽  
Vol 166 ◽  
pp. 10032
Author(s):  
Ordenbek Mazbayev ◽  
Lazat Alieva ◽  
Arman Demeuov
Keyword(s):  
Mass Transfer ◽  
The State ◽  
Educational Process ◽  
Geographical Education ◽  
New Model ◽  
Negative Results ◽  
Western Model ◽  
School Subjects

Geographical education in the post-Soviet countries after independence is oriented to the Western model of teaching disciplines. What positive and negative results have been obtained to date are discussed in this article. In the last four years, the educational process in schools has been focused on an updated program. As a result, an interesting question arises: how do we teach students? And this question, what subject we are studying, is moved to the background. The mass transfer of school subjects to a new model of education led to disintegration. In this article, the authors try to analyze the state of geographical education in Kazakhstan, to characterize the process of studying geographical disciplines from the seventh to the eleventh grade. As the authors of the updated textbook, we found many inconsistencies and issues that need to be addressed immediately. There is a model of geographical education, using the material of the updated program to preserve the traditions accumulated over the years of geographical education and upbringing.

scholarly journals Sensitivity of Global Mixing and Fluxes to Isolated Transport Barriers

2008 ◽  
Vol 65 (12) ◽  
pp. 3800-3818 ◽  
Author(s):  
Noboru Nakamura
Keyword(s):  
Decay Rate ◽  
Atmospheric Transport ◽  
Effective Diffusivity ◽  
Temporal Correlation ◽  
Barrier Properties ◽  
Decay Rates ◽  
Harmonic Mean ◽  
Transport Barriers ◽  
Decadal Variations ◽  
1D Model

Abstract Effects of isolated transport barriers on the global mixing and fluxes of a tracer are investigated, where a barrier is defined as a local minimum in effective diffusivity. An idealized 1D model with a prescribed diffusivity profile, with or without forcing, is used to show that the structure, flux, and decay rates of the tracer are all very sensitive to the barrier geometry, particularly when it is deep and narrow. Although the tracer gradients and the variance dissipation are concentrated to the barrier region, the flux shows a more global response to the barrier, decreasing everywhere. The harmonic mean of effective diffusivity is proposed as a useful first-order predictor of the global transport. This 1D model is used to diagnose the isentropic transport in the upper troposphere and lower stratosphere with offline transport calculations driven by the Met Office winds. The global tracer variance in these calculations decays approximately exponentially, and the time-mean decay rate and tracer structure are well captured by the gravest 1D eigenmode with the time-averaged effective diffusivity. However, the decay rate and the flux of the full solution are 15%–20% smaller than those of the eigenmode because of a negative temporal correlation between the effective diffusivity and the gradient. The vertical and decadal variations of the decay rates are consistent with the corresponding variations in the harmonic mean effective diffusivity. To the extent that the global mixing is sensitive to the local barrier properties, and to the extent that the latter are sensitive to the errors in advecting winds and model numerics, modeling of global atmospheric transport remains a challenge. This may explain, at least partially, the disparate model estimates reported in the literature.

Sign in / Sign up

Export Citation Format

Share Document