FORTRAN Subroutine Research Articles

Numerical investigation of optimum operating conditions for syngas and hydrogen production from biomass gasification using Aspen Plus

This study is dedicated to present a reliable numerical methodology using Aspen Plus process simulator capable of performing a sensibility analysis of the downdraft gasification of Portuguese forest residues. Effects of critical parameters, including gasification temperature and steam-to-biomass ratio (SBR) on composition of the produced gas are discussed. The sensibility analysis is conducted using Aspen Plus simulator incorporating Fortran subroutines. The model is validated by experimental data and found to be in good agreement. The results of the sensibility analysis performed using air as gasification agent indicate that higher temperatures are favourable for a produced gas with higher hydrogen content and heating value. The simulation results also demonstrate that the use of steam as gasification agent allows increasing the hydrogen content and heating value of the produced gas in comparison to the use of air as gasifying agent. The knowledge of this data is decisive to the development of projects concerning the use of Portuguese forest residues as energy source.

OpenFPCI: A parallel fluid–structure interaction framework

This paper presents OpenFPCI, a framework for coupling the C++ toolbox OpenFOAM-Extend, a computational fluid dynamics package, with the general purpose finite element package ParaFEM, written in Fortran and used to solve structural mechanics problems. The coupling of these two open source and scalable toolboxes, facilitates the use of high performance computing resources for the solution of fluid–structure interaction problems. The framework uses a master–slave approach, with OpenFOAM-Extend acting as the master and calling OpenFPCI plugins. The plugins are composed of a series of subroutines used to initialise and solve a specific engineering problem and make use of ParaFEM’s highly parallel implementation. The plugins are wrapped by C constructs such that OpenFOAM-Extend can call these Fortran subroutines consistently and when the solution from ParaFEM is required. Each plugin solves a different solid mechanics problem, with the current features including the deformation of a linear-elastic structure undergoing small strain and the deformation of a St. Venant–Kirchhoff material. Throughout this paper the focus will lie on the large strain plugin, considering the implementation and its validation for a benchmark problem, along with assessment of parallel capabilities, which are shown to scale to three thousand cores. This paper will be of interest to OpenFOAM and ParaFEM practitioners looking to utilise multiphysics simulations for their research, along with researchers looking to integrate fluid–structure interaction into their studies. Program summaryProgram Title:OpenFPCIProgram Files doi:http://dx.doi.org/10.17632/ntprzxk477.1Licensing provisions: BSD 2-ClauseProgramming language: Fortran, C and C++External libraries:OpenFOAM and ParaFEMSupplementary material: Example test cases are available within the OpenFPCI repository.Nature of problem: OpenFPCI was developed to solve computationally expensive fluid structure interaction problems by running on high performance computing systems. The framework was designed to enable the coupling of advanced ParaFEM capabilities to OpenFOAM-Extend.Solution method: OpenFOAM-Extend uses the classic Arbitrary Lagrangian–Eulerian formulation of the Navier–Stokes equations to deal with moving boundaries. The moving boundary is defined by using an OpenFPCI plugin, using ParaFEM’s libraries, to solve the deformation of the adjoining structure.

Simulation and Performance Investigation of a Biomass Gasification System for Combined Power and Heat Generation

The Blue Tower gasifier (BTG) is a promising and relatively new type of technology that can convert various organic materials into syngas. The process proceeds through a stage-reforming concept and uses heat carrier materials for indirect thermolysis. In addition, the modular design of this technology allows for scalability and ease of installation which can be applied to remote or off-grid communities. In addition, there is potential for the valorization of its gasification products to other useful chemicals. Knowing the potential advantages of this technology, the aim of this work is to introduce the BTG technology for potential application to remote communities and to investigate the effects of the main operational parameters on the performance of the system. In this study, we simulated a BTG system connected to a combined heat and power (CHP) plant using aspen plus with Fortran subroutines and given design specifications. The results obtained in this study were verified with reported data in the literature. The maximum electrical efficiency of the system was calculated to be about 25% for biomass with 5% moisture content, 0.5 steam to biomass ratio, and 900 °C reforming temperature. On the other hand, the highest overall system efficiency of the CHP system (sum of the electrical and the thermal efficiency) was estimated to be about 73% for biomass feedstock with 20% moisture content, 0.5 steam to biomass ratio, and 950 °C reforming temperature.

Analytical and Computational Methods for Solidification Problems of Liquid That Expands During Freezing

Both analytical and computational methods for solidification problems are introduced. First, the inward solidification process in a spherical vessel is studied. Expressions of the stress, displacement in the solid phase, and the liquid pressure are deduced based on the solidification interface position. A phase-change expansion orientation factor is introduced to characterize the nonisotropic expansion behavior at the freezing interface. Then, an efficient coupled thermomechanical finite-element method is proposed to evaluate the thermal stress, strain, displacement, and pressure in solidification problems with highly nonlinear constitutive relations. Two particular methods for treating the liquid phase with fixed-grid approaches are introduced. The thermal stress is computed at each integration point by integrating the elastoviscoplastic constitutive equations. Then, the boundary value problem described by the global finite-element equations is solved using the full Newton–Raphson method. This procedure is implemented into the finite-element package abaqus via a FORTRAN subroutine UMAT. Detailed implementation steps and the solution procedures are presented. The numerical model is validated first by the analytical solutions and then by a series of benchmark tests. Finally, an example of solidification in an open reservoir with a free liquid surface is introduced. Potential industrial applications of the numerical model are presented.

Catalytic Coal Gasification Process Simulation with Alkaline Organic Wastewater in a Fluidized Bed Reactor Using Aspen Plus

A co-gasification process was proposed both for treating alkaline organic wastewater and to promote coal gasification by the alkaline substances in situ. A catalytic gasification model was developed by introducing a catalytic correction factor to describe the catalytic effects quantitatively. An integrated process simulation was carried out using Aspen Plus equipped with FORTRAN subroutines. The model was verified using the root mean square error between the simulation results and experimental data from the literature. Syngas composition, cold gas efficiency, and carbon conversion efficiency were analyzed with respect to different operating conditions (reaction temperature, steam/coal ratio, and equivalence ratio). The optimal conditions are summarized based on a self-sufficient system by using sensitivity analysis: Gasification temperature of 700 °C, steam/coal ratio = 1.0, and equivalence ratio = 0.4.

Radial: A Fortran subroutine package for the solution of the radial Schrödinger and Dirac wave equations

The Fortran subroutine package radial for the numerical solution of the Schrödinger and Dirac wave equations of electrons in central potentials V(r) is described. The considered potentials are such that the function V(r)≡rV(r) is finite for all r and tends to constant values when r→0 and r→∞. This includes finite-range potentials as well as combinations of Coulomb and finite-range potentials. The function V(r) used in the numerical calculation is the natural cubic spline that interpolates a table of values provided by the user. The radial wave equations are solved by using piecewise exact power series expansions of the radial functions, which are summed up to the prescribed accuracy so that truncation errors can be completely avoided. The radial subroutines compute radial wave functions, eigenvalues for bound states and phase shifts for free states. Specific subroutines are also provided for computing the radial functions and phase shifts for free states of complex optical potentials having a finite-range absorptive imaginary part. The solution subroutines are accompanied by example main programs, as well as with specific programs that perform calculations relevant in atomic, nuclear, and radiation physics (the self-consistent solution of the Dirac–Hartee–Fock–Slater equations for neutral atoms and positive ions, and the calculation of cross sections for elastic scattering of high-energy electrons and positrons by atoms and of nucleons by nuclei). The distribution package includes a detailed manual with a description of the basic physics and the mathematical formulas implemented in the subroutines. Program summaryProgram Title:radialProgram Files doi:http://dx.doi.org/10.17632/h6nbws5h6s.1Licensing provisions: CC by NC 3.0Programming language: Fortran 90/95Supplementary material: Manual in pdf format. Includes a description of the basic physics, and the complete set of formulas implemented in the program.Journal reference of previous version: Comput. Phys. Commun. 90 (1995) 151–168.Does the new version supersede the previous version?: YesReasons for the new version: The present subroutine package contains a revision and extension of the radial subroutines [1], which have been recoded. The new subroutines implement a more accurate normalisation of bound states; the phase convention of Dirac’s central-field orbitals has been replaced with that of Rose [2]. Subroutines for computing free states of complex optical-model potentials with an absorptive imaginary part have been added to the package. Subroutines giving the coefficients of asymptotic power-series expansions of radial functions for bound and free orbitals are also included. Finally, the present package contains complementary programs that use the radial subroutines for solving generic problems of interest in atomic and nuclear physics, namely, the self-consistent solution of the Dirac–Hartree–Fock–Slater equations for free neutral atoms and positive ions, and the calculation of differential cross sections for elastic collisions of electrons and positrons with atoms, and the scattering of nucleons by nuclei. The package also includes a manual in pdf format with a summary of the underlying physics and a detailed description of the formulas and numerical algorithms implemented in the programs, as well as derivations of the most relevant components.Summary of revisions: The original subroutines have been recoded and extended to include 1) a more accurate normalisation of bound states, 2) the calculation of free states of complex optical-model potentials, 3) asymptotic power-series expansions of radial functions, and 4) three practical applications.Nature of problem: The radial subroutines solve the radial Schrödinger and Dirac wave equations for a particle in a central potential V(r). They deliver the radial function(s), the energy eigenvalue for bound orbitals, and the phase shift for free orbitals.Solution method: The potential function V(r)≡rV(r) is defined by a table of values for a grid of radii that is dense enough to allow accurate natural cubic spline interpolation. The radial function is calculated for the potential defined by the interpolating cubic spline by means of exact power-series expansions, which are summed up to the desired accuracy.Additional comments including restrictions and unusual features: The subroutines are not capable of computing either bound or free states with energies very close to zero. Since the power-series expansions of the radial functions define exact piecewise solutions of the radial wave equations, they can be summed up to the accuracy required by the user. Truncation errors are controlled by the tolerance parameter ϵ, which determines the accuracy of the series summations. With double-precision arithmetic and ϵ∼10−15 the results are affected by only round-off errors. The subroutines deliver the values of the radial functions on a grid of radii defined by the user, which may be different from the grid used to specify the potential.[1] Salvat, F., J.M. Fernández-Varea, and W. Williamson, Jr. (1995), “Accurate numerical solution of the radial Schrödinger and Dirac wave equations.” Comput. Phys. Commun. 90, 151–168.[2] Rose, M.E. (1961), Relativistic Electron Theory (John Wiley and Sons, New York).

Study on the Influence of Right Atrial Pressure on the Numerical Calculation of Fractional Flow Reserve

Coronary atherosclerotic heart disease, or coronary heart disease for short, is a heart disease caused by atherosclerotic lesions of coronary arteries, resulting in stenosis, spasm and live obstruction, leading to myocardial ischemia, hypoxia and even necrosis, and is the most common type of organ lesions caused by atherosclerosis. Coronary computed tomograph angiography (CCTA) has been the most effective method for examining coronary heart disease, but this method can only be judged from the morphology. It has been shown that when the coronary stenosis rate is as high as 70%, only 32% of blood vessels can cause myocardial ischemia. Therefore, there is no direct relationship between coronary stenosis and myocardial ischemia. Long-term clinical studies have shown that the determination of fractional flow reserve (FFR) is the gold standard for the current diagnosis of hemodynamic changes in coronary artery stenosis. FFR is invasive, expensive and technically demanding for operators, which greatly limits clinical use. FFR-CT, which is derived by CCTA and Computational fluid dynamics (CFD), is a new noninvasive method for assessing coronary stenosis. Initially, FFR was calculated by Myo= (pd-pv) /(pa-pv), where Pd (distal pressure) was stenosis, Pa (proximal arterial pressure) was stenosis, and Pv (venous pressure or right atrial pressure, RAP) was right atrial pressure. Since Pv is small, usually 4~8mmHg, a simplified formula can be used for literature expenditure, namely, Myo=Pd/Pa. However, due to the small amount of clinical data, it is impossible to determine whether Pv has an influence on the calculation of FFR. Therefore, an ideal vascular model with a diameter of 3 mm, a stenosis length of 10 mm, and a stenosis degree of 40%, 50%, 60%, and 70%, respectively, was established. This study defines interface conditions and special coupling algorithms for 0D/3D coupling. ANSYS-CFX is used in 3d simulation, and the 0D model is calculated with Fortran subroutine based on CFX Junction Box. Data exchange between the 0D and 3D models is implemented using CFX User CEL Function. A constant pressure of 90mmHg was applied at the model entrance, and a constant resistance Rmicro was provided at the outlet boundary to simulate the microcirculation resistance in the downstream hyperemia state. Pv was given at the resistance end, and the values were respectively 0mmHg, 4mmHg, 6mmHg and 8mmHg. Three cardiac cycles are calculated, and the cardiac cycle is 0.8s.The calculation results of the last period are extracted after the result converges. It was calculated that when the stenosis degree was 40%, Pv was 0 mmHg, FFR=0.913; when Pv was 8 mmHg, FFR=0.921; the rate of change was 0.876%. When the degree of stenosis is 50%, Pv is 0 mmHg, FFR=0.87; when Pv is 8 mmHg, FFR=0.883; the rate of change is 1.49%. When the degree of stenosis is 60%, Pv is 0 mmHg, FFR=0.776; when Pv is 8 mmHg, FFR=0.799; the rate of change is 2.96%. When the degree of stenosis is 70%, Pv is 0 mmHg, FFR=0.579; when Pv is 8 mmHg, FFR=0.623; the rate of change is 7.60%. The results show that with the increase of Pv, the calculated value of FFR also increases; and as the degree of stenosis increases, the degree of influence of Pv deepens. In the actual situation, the patient's right atrial pressure is not 0 mmHg, so in order to improve the accuracy of FFR calculation, Pv should be taken into consideration, and the calculation formula should not be simplified.

Analysis of interface delamination in thermal barrier coating system with axisymmetric structure based on corresponding normal and tangential stresses

The interface delamination plays an important role in failures of thermal barrier coatings. An axisymmetric finite element model was built for air plasma sprayed thermal barrier coatings. The model incorporated a Fortran subroutine developed for the TGO growth. It is found that the stress conversion happens in the top-coat at high temperature under isothermal exposure. A simple numerical method was proposed to calculate the normal and tangential stresses at the top-coat/TGO interface and the bond-coat/TGO interface. The bond-coat/TGO interface is less likely to separate during thermal exposure because the interfacial stresses are limited mostly by the high-temperature yield strength of the bond-coat. The delamination of the bond-coat/TGO interface happens on cooling, which is supported by the experimental observation. As a result, the delamination of the bond-coat/TGO interface could be appreciated based on the corresponding normal and tangential stresses.

Material removal analysis for compliant polishing tool using adaptive meshing technique and Archard wear model

In this paper, a simulation technique to predict the material removal profile is developed for a disc-shaped compliant polishing tool which is commonly used in robotic polishing. The methodology is based on the Archard wear model implemented with adaptive meshing technique in the commercial finite element ABAQUS® software. Initially, the effect of tool compliance on the static contact pressure distribution is investigated experimentally using pressure films. Numerical 3D finite element model is developed for the same in order to predict the contact pressure distribution which in turn influences the material removal profile prediction. The material removal study is carried out with a robotic arm, and the polished surface is later scanned for the material removal profile. In order to predict the material removal profile, the finite element simulation in ABAQUS® is carried out using ‘dynamic-implicit’, followed by executing the umeshmotion FORTRAN subroutine in the ‘general-static’, where the nodes are displaced based on the wear model and using Arbitrary Lagrangian-Eulerian (ALE). The results are again imported in dynamic implicit and the simulation is restarted. The cycle continues till the experimental polishing time is reached. The experimental and simulation results of contact pressure are in good agreement with each other and bring out the effect of tool compliance on dynamic pressure which in turns affects the overall three-dimensional material removal profile.

Manual of BlackMax. A black-hole event generator with rotation, recoil, split branes, and brane tension. Version 2.02

This is the users manual of the black-hole event generator BlackMax (Dai et al., 2008), which simulates the experimental signatures of microscopic and Planckian black-hole production and evolution at proton–proton, proton–antiproton and electron–positron colliders in the context of brane world models with low-scale quantum gravity. The generator is based on phenomenologically realistic models free of serious problems that plague low-scale gravity. It includes all of the black-hole gray-body factors known to date and incorporates the effects of black-hole rotation, splitting between the fermions, non-zero brane tension and black-hole recoil due to Hawking radiation (although not all simultaneously). The main code can be downloaded from Dai et al. (0000). Program summaryProgram title: BlackMaxProgram Files doi:http://dx.doi.org/10.17632/p9jg9dypcg.1Licensing provisions: GNU General Public License version 3Programming language: C (with Fortran subroutines)Nature of problem: In the class of models with low scale quantum gravity (known as the “TeV scale gravity models”) collisions of particles at the particle accelerators may lead to novel phenomena, in particular mini black hole production. In order to confirm or exclude this class of models, one needs to calculate the probability of the black hole production in collisions of particles, properties of the formed black holes (mass, spin, charge, momentum), and the signature of the black hole decay (Hawking radiation).Solution method: BlackMax calculates the probability of the black hole production by utilizing the so-called “geometric cross section” for black hole production. From the energy and quantum numbers of the colliding particles BlackMax calculates the mass, spin, charge, and momentum of the formed black holes. In the next step, BlackMax utilizes the greybody factors that characterize Hawking radiation and calculates the final output. The produced particles are then supposed to leave the signature in particle detectors.

Environmental analysis of municipal solid waste combustion in a fluidized bed

ABSTRACTA steady-state Aspen Plus model of municipal solid waste (MSW) combustion has been developed to simulate the influence of operating conditions and hydrodynamic parameters on the concentrations of air pollutants and performance indicators. To simulate the hydrodynamic characteristics, a FORTRAN subroutine was coupled to Aspen Plus software. Model validated against the experimental data is available in the literature and found to be in good agreement. Results showed that the operating pressure has a negligible influence on gas composition and performance indicators, but it plays a major role in the commercialization of thermal conversion of carbon-based fuels due to a significant reduction in the capital costs. It was also concluded that as the Umf increases from 1.2 to 2.5, the concentrations of pollutants released increase, probably due to a considerable decrease in the rate of reactions involved, especially at the end of combustor.

Implementation of EOQ and Lambert W function in 1-D engine simulation model for optimizing fuel injection in GDI engine

• A novel and unique approach based on EOQ for optimizing fuel injection is implemented. • A scheme for coupling crank angle resolved model with EOQ in MATLAB SIMULINK. • Predictive combustion model with EOQ is sufficient for optimizing fuel quantity. • Proposes EOQ with Lambert W function for model based engine calibration approach. The aim of this study was to implement Economic Order Quantity method (EOQ) together with the Lambert W function in a 1-D engine simulation model in order to develop a fuel control strategy for a Gasoline direct injection (GDI) engine. Previous work of the co-author demonstrated the possibility of optimizing fuel injection quantity in GDI engine using the EOQ that is commonly used in supply chain of perishable products. This work extends the previous work and implements it in a 1-D, crank angle resolved, engine simulation model for the application of model based calibration process. The present work uses a validated engine simulation model, which is based on predictive combustion modelling approach, and couples the 1-D engine simulation model with SIMULINK to add the evaporation, wall- wetting and heat transfer models . It employs FORTRAN subroutines to modify the internal code of the 1-D simulation software in order to add crank angle resolved evaporation model. Finally, EOQ with Lambert W function was added to the model using MATLAB with special attention to the decimal control for the solution. This study demonstrated that EOQ and Lambert W functions together are a suitable method to develop fuel control strategy for a model based calibration procedure when implemented in crank angle resolved 1-D simulation model.

Capture cross section with quantum diffusion approach

A C++ code for calculating the capture of a projectile by target nucleus is described. The code is based on the quantum diffusion model developed for considering collisions of nuclei at energies below and above the Coulomb barrier. The code provides the capture cross sections and other characteristics of reaction as functions of Ec.m.. The formalism of the model is briefly described. The code contains the Fortran subroutine to calculate the nucleus–nucleus potential. Program summaryProgram title: NuclearCaptureProgram files doi: http://dx.doi.org/10.17632/n66yg8mdzs.1Licensing provisions: GNU General Public License v2Programming language: C++, FortranExternal routines/libraries: GSL-2.2.1 GNU Scientific Library in C++ is required. It is available from https://www.gnu.org/software/gsl .Nature of problem: Capture of colliding nuclei at energies below and above the Coulomb barrierSolution method: Non-Markovian quantum Langevin equations

Experimental and numerical dynamic analysis of laminate plates via Carrera Unified Formulation

This work consists on evaluating potentialities and limitations of finite element formulations developed via CUF to predict free vibration response of laminated composite plates by using real experiments. Therefore, finite elements were developed via Carrera’s Unified Formulation (CUF) for laminated plates, which were implemented as a FORTRAN subroutine (UEL – User Element subroutine) linked to commercial finite element software ABAQUS™, to simulate free vibration of composite laminates. In addition, laminated plates made of composite material, resin epoxy and carbon fibre, with two different layups, were submitted to experimental vibration tests. The experimental tests were carried out by using an impact hammer, which excited the structure with impulse signal, and accelerometers, which measured the output data. Dynamic characteristics, such as natural frequencies, mode shapes and Frequency Response Functions were presented for the specimens. Then numerical results were compared to real experiments, discussing different aspects of the formulated finite elements. In addition, there is a demonstration how to connect native finite elements from ABAQUS™ to elements formulated via CUF (using UEL subroutines) and how to solve this problem using numerical time integration algorithms implemented in ABAQUS™, including discussion about the influence of time integration parameters on the dynamic response.

CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

Bubble surface area flux (Sb) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type, density, wettability and concentration on Sb. In this paper, computational fluid dynamics (CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-ε turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014. This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sb and bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite. A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle (i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted when the system was working with hydrophobic particles. The results presented are useful for understanding flow dynamics of three-phase system and provide a basis for further development of CFD model for flotation column.

Conversion coefficients calculation of mono-energetic photons from air-kerma using Monte Carlo and analytical methods

This study is aimed to calculate the conversion coefficients H∗(10)/Φ form air-kerma for beams of mono-energetic photons, which incident on ICRU sphere diameter 30 cm of ICRU tissues material with a density of 1 g/cm3 four-element tissue and a weight composition of 76.2% oxygen, 11.1% carbon, 10.1% hydrogen and 2.6% nitrogen (ICRU 57, 1997). The conversion coefficients are calculated using two methods: the DOSRZnrc based on EGSnrc code (Kawrakow et al., 2017) and our developed FORTRAN subroutine which evaluates the analytical expression available from a fit to Monte Carlo calculations (Veinot and Hertel, 2011). Our results have been carried out for absorbed dose and kerma approximations, for mono-energetic photons from 15 keV to 10 MeV. The results obtained were compared to those published by ICRU reports (ICRP Publication 74, 1996; ICRU 57, 1997). A good agreement with reference data with a local difference less than 2% was found.

Thermoelastic Crack Analysis in Functionally Graded Pipelines Conveying Natural Gas by an FEM

Internal cracks are a serious problem in pipelines conveying unsteady pressurized fluids like natural gas. To investigate and overcome this problem, this paper is motivated to highlight and study the response of gas pipes made of functionally graded materials (FGM) instead of the traditional carbon steel material. FGM is proposed as a composite material because of its advantages of minimizing the stress variation in the pipe. Ceramic is applied because of its durability against corrosion and its surface hardness against erosion. FGM properties are radially graded and a finite element model is developed and implemented into ABAQUS package, including FORTRAN subroutines which are adapted for the present case study. Coupled plane strain thermoelastic analysis is used to investigate the stresses and the stress intensity factor (SIF) at various crack depths under the actual thermomechanical loads. Both coupled and uncoupled thermomechanical approaches are introduced and compared to reveal the necessity of the coupled analysis for accurate FGMs’ investigation. The different influences of unsteady thermal and mechanical loads on the crack propagation are discussed.

Thermal Energy Storage Configurations for Small Modular Reactor Load Shedding

The increased penetration of intermittent renewable energy technologies such as wind and solar power can strain electric grids, forcing carbon-based and nuclear sources of energy to operate in a load-follow mode. For nuclear reactors, load-follow operation can be undesirable due to the associated thermal and mechanical stresses placed on the fuel and other reactor components. Various methods of thermal energy storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid variability caused by daily load demand changes and renewable intermittency. Two TES techniques are investigated as candidate thermal reservoirs to be used in conjunction with a small modular reactor (SMR): a two-tank sensible heat storage system and a stratified chilled-water storage system. The goal when coupling the two systems to the SMR is to match turbine output and demand and bypass steam to the TES systems to maintain reactor power at approximately 100%. Simulations of integral pressurized water reactor dynamics are run in a high-fidelity FORTRAN model developed at North Carolina State University. Both TES systems are developed as callable FORTRAN subroutines to model the time-varying behavior associated with different configurations of these systems when connected to the SMR simulator. Simulation results reveal the sensible heat storage system is capable of meeting turbine demand and maintaining reactor power constant while providing enough steam to power four absorption chillers for chilled-water production and storage. The stored chilled water is used to supplement cooling loads of an adjacent facility.

Dynamic plastic response of double-layered circular metallic plates due to localized impulsive loading

In this paper, the dynamic plastic response of double-layered circular metallic plates subjected to localized impulsive loading was investigated both numerically and empirically. A numerical model was developed in commercial finite element code ABAQUS/Explicit via a user user-defined FORTRAN subroutine in conjunction with the Johnson–Cook thermo-viscoplasticity and damage models. The numerical results were validated with the available experimental results. Next, rigorous parametric studies were conducted on double-layered plates made of Weldox 460E, Aluminum 1100-H12 and a combination of these materials with copper plates for the impulse range of 10–110 N.s. Finally, dimensional analysis of the parametric study was performed and new empirical design formulas were derived for prediction of central deflections of back and front layers based on the suggested dimensionless numbers. The numbers considered the effect of the structural geometry, the inertia of applied dynamic load, the material resistance ability to the plastic deformation, the strain rate sensitivity of the material, and the load ratio both for front and back layers. The comparison between parametric study results and proposed empirical expressions illustrated that the derived equations provided quite reliable and accurate predictions of the central deflections of back and front layers when the deflections changed ranging from 11.4 mm to 62.8 mm.

A tracking algorithm for Monte Carlo simulation of surface roughness in EPMA measurements

We present an algorithm for Monte Carlo simulation of particle trajectories through rough interfaces. The microscopic topography of the rough surface is assumed to be described by an altitude map in a dense rectangular grid. The tracking algorithm has been implemented in a Fortran subroutine package, which is coupled to the code system PENELOPE/PENEPMA to perform Monte Carlo simulations of X-ray emission from samples with rough surfaces irradiated by electron beams. To validate the numerical procedure, electron probe microanalysis (EPMA) simulations of an ideal sample with periodic surface roughness have been performed by using 1) the PENGEOM geometry package of the PENELOPE code system and 2) the new tracking algorithm. The results from the two simulations are found to be equivalent, that is, their differences are generally less than the associated statistical uncertainties. Results from simulations of samples with realistic rough surfaces are also presented.