Academic literature on the topic 'Compressibility Heat Fluid dynamics Porous materials'
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Journal articles on the topic "Compressibility Heat Fluid dynamics Porous materials"
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Malan, A. G., and R. W. Lewis. "An artificial compressibility CBS method for modelling heat transfer and fluid flow in heterogeneous porous materials." International Journal for Numerical Methods in Engineering 87, no. 1-5 (February 11, 2011): 412–23. http://dx.doi.org/10.1002/nme.3125.
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Shajii, A., and J. P. Freidberg. "Theory of low Mach number compressible flow in a channel." Journal of Fluid Mechanics 313 (April 25, 1996): 131–45. http://dx.doi.org/10.1017/s0022112096002157.
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The properties of a relatively uncommon regime of fluid dynamics, low Mach number compressible flow are investigated. This regime, which is characterized by an exceptionally large channel aspect ratio L/d ∼ 106 leads to highly subsonic flows in which friction dominates inertia. Even so, because of the large aspect ratio, finite pressure, temperature, and density gradients are required, implying that compressibility effects are also important. Analytical results are presented which show, somewhat unexpectedly, that for forced channel flow, steady-state solutions exist only below a critical value of heat input. Above this value the flow reverses against the direction of the applied pressure gradient causing fluid to leave both the inlet and outlet implying that the related concepts of a steady-state friction factor and heat transfer coefficient have no validity.
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Romano, V., U. Tammaro, and P. Capuano. "A 2-D FEM thermal model to simulate water flow in a porous media: Campi Flegrei caldera case study." Nonlinear Processes in Geophysics 19, no. 3 (May 10, 2012): 323–33. http://dx.doi.org/10.5194/npg-19-323-2012.
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Abstract. Volcanic and geothermal aspects both exist in many geologically young areas. In these areas the heat transfer process is of fundamental importance, so that the thermal and fluid-dynamic processes characterizing a viscous fluid in a porous medium are very important to understand the complex dynamics of the these areas. The Campi Flegrei caldera, located west of the city of Naples, within the central-southern sector of the large graben of Campanian plain, is a region where both volcanic and geothermal phenomena are present. The upper part of the geothermal system can be considered roughly as a succession of volcanic porous material (tuff) saturated by a mixture formed mainly by water and carbon dioxide. We have implemented a finite elements approach in transient conditions to simulate water flow in a 2-D porous medium to model the changes of temperature in the geothermal system due to magmatic fluid inflow, accounting for a transient phase, not considered in the analytical solutions and fluid compressibility. The thermal model is described by means of conductive/convective equations, in which we propose a thermal source represented by a parabolic shape function to better simulate an increase of temperature in the central part (magma chamber) of a box, simulating the Campi Flegrei caldera and using more recent evaluations, from literature, for the medium's parameters (specific heat capacity, density, thermal conductivity, permeability). A best-fit velocity for the permeant is evaluated by comparing the simulated temperatures with those measured in wells drilled by Agip (Italian Oil Agency) in the 1980s in the framework of geothermal exploration. A few tens of days are enough to reach the thermal steady state, showing the quick response of the system to heat injection. The increase in the pressure due to the heat transport is then used to compute ground deformation, in particular the vertical displacements characteristics of the Campi Flegrei caldera behaviour. The vertical displacements range from 1 cm to 10 cm in accordance with the mini uplift, characterizing the recent behaviour of the caldera. The time needed to move fluid particles from the bottom to the upper layer (years) is compatible with the timing of the mini uplift.
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Cortellessa, Gino, Fausto Arpino, Simona Di Fraia, and Mauro Scungio. "Two-phase explicit CBS procedure for compressible viscous flow transport in porous materials." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 2 (February 5, 2018): 336–60. http://dx.doi.org/10.1108/hff-02-2017-0080.
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Purpose In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for the first time to heat and mass transfer phenomena in porous media with associated phase change. The purpose of this study is to provide an alternative for the theoretical analysis and numerical simulation of multiphase transport phenomena in porous media. Traditionally, the more complex Separate Flow Model was used in which the vapour and liquid phases were considered as distinct fluids and mathematically described by the conservation laws for each phase separately, resulting in a large number of governing equations. Design/methodology/approach Even though the adopted mathematical model presents analogies with the conventional multicomponent mixture flow model, it is characterized by a considerable reduction in the number of the differential equations for the primary variables. The fixed-grid numerical formulation can be applied to the resolution of general problems that may simultaneously include a superheated vapour region, a two-phase zone and a sub-cooled liquid region in a single physical domain with irregular and moving phase interfaces in between. The local thermal non-equilibrium model is introduced to consider the heat exchange between fluid and solid within the porous matrix. Findings The numerical model is verified considering the transport phenomena in a homogenous and isotropic porous medium in which water is injected from one side and heated from the other side, where it leaves the computational domain in a superheated vapour state. Dominant forces are represented by capillary interactions and two-phase heat conduction. The obtained results have been compared with the numerical data available in the scientific literature. Social implications The present algorithm provides a powerful routine tool for the numerical modelling of complex two-phase transport processes in porous media. Originality/value For the first time, the stabilized AC-CBS scheme is applied to the resolution of compressible viscous flow transport in porous materials with associated phase change. A properly stabilized matrix inversion-free procedure employs an adaptive local time step that allows acceleration of the solution process even in the presence of large source terms and low diffusion coefficients values (near the phase change point).
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Azadbakhti, Reza, Farzad Pourfattah, Abolfazl Ahmadi, Omid Ali Akbari, and Davood Toghraie. "Eulerian–Eulerian multi-phase RPI modeling of turbulent forced convective of boiling flow inside the tube with porous medium." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 5 (July 17, 2019): 2739–57. http://dx.doi.org/10.1108/hff-03-2019-0194.
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Purpose The purpose of this study is simulation the flow boiling inside a tube in the turbulent flow regime for investigating the effect of using a porous medium in the boiling procedure. Design/methodology/approach To ensure the accuracy of the obtained numerical results, the presented results have been compared with the experimental results, and proper coincidence has been achieved. In this study, the phase change phenomenon of boiling has been modeled by using the Eulerian–Eulerian multi-phase Rensselaer Polytechnic Institute (RPI) wall boiling model. Findings The obtained results indicate using a porous medium in boiling process is very effective in a way that by using a porous medium inside the tub, the location of changing the liquid to the vapor and the creation of bubbles, changes. By increasing the thermal conductivity of porous medium, the onset of phase changing postpones, which causes the enhancement of heat transfer from the wall to the fluid. Generally, it can be said that using a porous medium in boiling flows, especially in flow with high Reynolds numbers, has a positive effect on heat transfer enhancement. Also, the obtained results revealed that by increasing Reynolds number, the created vapor phase along the tube decreases and by increasing Reynolds number, the Nusselt number enhances. Originality/value In present research, by using the computational fluid dynamics, the effect of using a porous medium in the forced boiling of water flow inside a tube has been investigated. The fluid boiling inside the tube has been simulated by using the multi-phase Eulerian RPI wall boiling model, and the effect of thermal conductivity of a porous medium and the Reynolds number on the flow properties, heat transfer and boiling procedure have been investigated.
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Massarotti, Nicola, Michela Ciccolella, Gino Cortellessa, and Alessandro Mauro. "New benchmark solutions for transient natural convection in partially porous annuli." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 3/4 (May 3, 2016): 1187–225. http://dx.doi.org/10.1108/hff-11-2015-0464.
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Purpose – The purpose of this paper is to focus on the numerical analysis of transient free convection heat transfer in partially porous cylindrical domains. The authors analyze the dependence of velocity and temperature fields on the geometry, by analyzing transient flow behavior for different values of cavity aspect ratio and radii ratio; both inner and outer radius are assumed variable in order to not change the difference ro-ri. Moreover, several Darcy numbers have been considered. Design/methodology/approach – A dual time-stepping procedure based on the transient artificial compressibility version of the characteristic-based split algorithm has been adopted in order to solve the transient equations of the generalized model for heat and fluid flow through porous media. The present model has been validated against experimental data available in the scientific literature for two different problems, steady-state free convection in a porous annulus and transient natural convection in a porous cylinder, showing an excellent agreement. Findings – For vertically divided half porous cavities, with Rayleigh numbers equal to 3.4×106 for the 4:1 cavity and 3.4×105 for the 8:1 cavity, the numerical results show that transient oscillations tend to disappear in presence of cylindrical geometry, differently from what happens for rectangular one. The magnitude of this phenomenon increases with radii ratio; the porous layer also affects the stability of velocity and temperature fields, as oscillations tend to decrease in presence of a porous matrix with lower value of the Darcy number. Research limitations/implications – A proper analysis of partially porous annular cavities is fundamental for the correct estimation of Nusselt numbers, as the formulas provided for rectangular domains are not able to describe these problems. Practical implications – The proposed model represents a useful tool for the study of transient natural convection problems in porous and partially porous cylindrical and annular cavities, typical of many engineering applications. Moreover, a fully explicit scheme reduces the computational costs and ensures flexibility. Originality/value – This is the first time that a fully explicit finite element scheme is employed for the solution of transient natural convection in partially porous tall annular cavities.
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Qi, Xiaoni, and Yongqi Liu. "Heat Storage Performance of a Honeycomb Ceramic Monolith." Open Fuels & Energy Science Journal 7, no. 1 (December 31, 2014): 113–20. http://dx.doi.org/10.2174/1876973x01407010113.
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Honeycomb ceramic is the key component of the regenerative system. The three-dimensional numerical model has been established for thermal process in honeycomb regenerator. The numerical simulation was performed using FLUENT, a commercial computational fluid dynamics (CFD) code, to compare simulation results to the test data. The regenerative process of a honeycomb ceramic regenerator was simulated under different conditions. The results under different flow rates, different flowing time, different materials and different wall thickness were investigated. The work in this paper provides a theory basis and guide to the exploitation and appliance of HTAC system and the results of the numerical calculation can be used as the foundation of engineering design. The results may be utilized for design of porous media reactors and process optimization.
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Otomo, Yusuke, Edgar Santiago Galicia, and Koji Enoki. "Enhancement of Subcooled Flow Boiling Heat Transfer with High Porosity Sintered Fiber Metal." Applied Sciences 11, no. 3 (January 29, 2021): 1237. http://dx.doi.org/10.3390/app11031237.
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We conducted experimental research using high-porosity sintered fiber attached on the surface, as a passive method to increase the heat flux for subcooled flow boiling. Two different porous thicknesses (1 and 0.5 mm) and one bare surface (0 mm) were compared under three different inlet subcooling temperatures (30, 50 and 70 K) and low mass flux (150–600 kg·m−2·s−1) using deionized water as the working fluid under atmospheric pressure. The test section was a rectangular channel, and the hydraulic diameter was 10 mm. The results showed that the heat flux on porous surfaces with a thickness of 1 and 0.5 mm increased by 60% and 40%, respectively, compared to bare surfaces at ΔTsat = 40 K at a subcooled temperature of 50 K and mass flux of 300 kg·m−2·s−1. An abrupt increase in the wall superheat was avoided, and critical heat flux (CHF) was not reached on the porous surfaces. The flow pattern and bubble were recorded with a high-speed camera, and the bubble dynamics are discussed.
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Xing, Z. B., Xingchao Han, Hanbing Ke, Q. G. Zhang, Zhiping Zhang, Huijin Xu, and Fuqiang Wang. "Multi-phase lattice Boltzmann (LB) simulation for convective transport of nanofluids in porous structures with phase interactions." International Journal of Numerical Methods for Heat & Fluid Flow 31, no. 8 (March 22, 2021): 2754–88. http://dx.doi.org/10.1108/hff-07-2020-0481.
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Purpose A combination of highly conductive porous media and nanofluids is an efficient way for improving thermal performance of relevant applications. For precisely predicting the flow and thermal transport of nanofluids in porous media, the purpose of this paper is to explore the inter-phase coupling numerical methods. Design/methodology/approach Based on the lattice Boltzmann (LB) method, this study combines the convective flow, non-equilibrium thermal transport and phase interactions of nanofluids in porous matrix and proposes a new multi-phase LB model. The micro-scale momentum and heat interactions are especially analyzed for nanoparticles, base fluid and solid matrix. A set of three-phase LB equations for the flow/thermal coupling of base fluid, nanoparticles and solid matrix is established. Findings Distributions of nanoparticles, velocities for nanoparticles and the base fluid, temperatures for three phases and interaction forces are analyzed in detail. Influences of parameters on the nanofluid convection in the porous matrix are examined. Thermal resistance of nanofluid convective transport in porous structures are comprehensively discussed with the models of multi-phases. Results show that the Rayleigh number and the Darcy number have significant influences on the convective characteristics. The result with the three-phase model is mildly larger than that with the local thermal non-equilibrium model. Originality/value This paper first creates the multi-phase theoretical model for the complex coupling process of nanofluids in porous structures, which is useful for researchers and technicians in fields of thermal science and computational fluid dynamics.
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MOHAMMADI, ALIASGHAR, and REGHAN J. HILL. "Dynamics of uncharged colloidal inclusions in polyelectrolyte hydrogels." Journal of Fluid Mechanics 669 (January 14, 2011): 298–327. http://dx.doi.org/10.1017/s0022112010005045.
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We calculate the dynamics of an uncharged colloidal sphere embedded in a quenched polyelectrolyte hydrogel to (i) an oscillatory (optical and magnetic) force, as adopted in classical micro-rheology, and (ii) an oscillatory electric field, as adopted in electrical micro-rheology and electro-acoustics. The hydrogel is modelled as a linearly elastic porous medium with the charge fixed to the skeleton and saturated with a Newtonian electrolyte; and the colloidal inclusion is modelled as a rigid, impenetrable sphere. The dynamic micro-rheological susceptibility, defined as the ratio of the particle displacement to the strength of an applied oscillatory force, depends on the fixed-charge density and ionic strength and is bounded by the limits for incompressible and uncharged, compressible skeletons. Nevertheless, the influences of fixed charge and ionic strength vanish at frequencies above the reciprocal draining time, where the polymer and the electrolyte hydrodynamically couple as a single incompressible phase. Generally, the effects of fixed charge and ionic strength are small compared with, for example, the influences of polymer slip at the particle surface. The electrical susceptibility, defined as the ratio of the particle displacement to the strength of an applied oscillatory electric field, is directly influenced by charge at all frequencies, irrespective of skeleton compressibility. At low frequencies, polymer charge modulates the driving (electro-osmotic) and restoring (electrostatically enhanced elastic) forces, whereas charge has no influence on the restoring force at high frequencies where dilational strain is suppressed by hydrodynamic coupling with the electrolyte. In striking contrast to charged inclusions in uncharged hydrogels (Wang & Hill, J. Fluid Mech., vol. 640, 2009, pp. 357–400), the electrical susceptibility at high frequencies is independent of electrolyte concentration. Rather, the dynamics primarily reflect the elastic modulus, charge and hydrodynamic permeability, with a relatively weak dependence on particle size. Interestingly, the dynamic mobility in the zero-momentum reference frame, which is central to the electro-acoustic response, is qualitatively different from the dynamic mobility in the skeleton-fixed reference frame. Finally, we propose a phenomenological harmonic-oscillator model to address – in an approximate manner – the dynamics of charged particles in charged hydrogels. This shows that particle dynamics at low frequencies are dominated by particle charge, whereas high-frequency dynamics are dominated by hydrogel charge.
Dissertations / Theses on the topic "Compressibility Heat Fluid dynamics Porous materials"
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Harvey, Jeremy Paul. "Oscillatory compressible flow and heat transfer in porous media application to cryocooler regenerators /." Diss., Available online, Georgia Institute of Technology, 2003:, 2003. http://etd.gatech.edu/theses/available/etd-11022003-000618/unrestricted/HarveyJeremyP200312.pdf.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2004.Desai, Prateen V., Committee Chair; Ghiaasiaan, S. Mostafa, Committee Member; Yoda, Minami, Committee Member; Kirkconnell, Carl S., Committee Member; Morris, Jeffrey F., Committee Member. Includes bibliographical references.
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Harvey, Jeremy Paul. "Parametric Study of Cryocooler Regenerator Performance." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15480.
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Visser, Coert Johannes. "Modelling heat and mass flow through packed pebble beds a heterogeneous volume-averaged approach /." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-08292008-125630/.
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Psimas, Michael J. "Experimental and numerical investigation of heat and mass transfer due to pulse combustor jet impingement." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33863.
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Under certain circumstances pulse combustors have been shown to improve both heat transfer and drying rate when compared to steady flow impingement. Despite this potential, there have been few investigations into the use of pulse combustor driven impingement jets for industrial drying applications. The research presented here utilized experimental and numerical techniques to study the heat transfer characteristics of these types of oscillating jets when impinging on solid surfaces and the heat and mass transfer when drying porous media. The numerical methods were extensively validated using laboratory heat flux and drying data, as well as correlations from literature. As a result, the numerical techniques and methods that were developed and employed in this work were found to be well suited for the current application. It was found that the pulsating flows yielded elevated heat and mass transfer compared to similar steady flow jets. However, the numerical simulations were used to analyze not just the heat flux or drying, but also the details of the fluid flow in the impingement zone that resulted in said heat and mass transport. It was found that the key mechanisms of the enhanced transfer were the vortices produced by the oscillating flow. The characteristics of these vortices such as the size, strength, location, duration, and temperature, determined the extent of the improvement. The effects of five parameters were studied: the velocity amplitude ratio, oscillation frequency, the time-averaged bulk fluid velocity at the tailpipe exit, the hydraulic diameter of the tailpipe, and the impingement surface velocity. Analysis of the resulting fluid flow revealed three distinct flow types as characterized by the vortices in the impingement zone, each with unique heat transfer characteristics. These flow types were: a single strong vortex that dissipated before the start of the next oscillation cycle, a single persistent vortex that remained relatively strong at the end of the cycle, and a strong primary vortex coupled with a short-lived, weaker secondary vortex. It was found that the range over which each flow type was observed could be classified into distinct flow regimes. The secondary vortex and persistent vortex regimes were found to enhance heat transfer. Subsequently, transition criteria dividing these regimes were formed based on dimensionless parameters. The critical dimensionless parameters appeared to be the Strouhal number, a modified Strouhal number, the Reynolds number, the velocity amplitude ratio, and the H/Dh ratio. Further study would be required to determine if these parameters offer similar significance for other configurations.
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Tavares, Renato Normandia. "Simulação numérica da convecção mista em cavidade preenchida com meio poroso heterogêneo e homogêneo." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/1657.
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No presente trabalho é apresentada a modelagem e solução numérica da convecção mista em cavidade aquecida por baixo com o topo deslizante, preenchida com meio poroso heterogêneo e homogêneo. Na abordagem heterogênea, o domínio do sólido é representado por blocos condutores de calor igualmente espaçados; a fase fluido circunda os blocos, limitada pelas paredes da cavidade. A abordagem homogênea ou poro-contínua é caracterizada através da porosidade e da permeabilidade da cavidade. As equações de conservação da massa, quantidade de movimento e energia são obtidas, adimensionalizadas e generalizadas de modo a representarem tanto o modelo contínuo quanto o poro-contínuo. A solução numérica é obtida através do método dos volumes finitos. As equações são discretizadas via esquema QUICK e é utilizado o algoritmo SIMPLE para o acoplamento pressão - velocidade. Visando o regime laminar, os parâmetros do escoamento são mantidos no intervalo de 102≤Re≤103 e 103≤Ra≤106 tanto para a abordagem heterogênea, quanto para a homogênea. Nas configurações testadas para o modelo contínuo, 9, 16, 36 e 64 blocos são considerados para cada combinação de Re e Ra e a porosidade microscópica é mantida constante φ=0,64 . No modelo poro-contínuo o número de Darcy (Da) é definido em função do número de blocos da cavidade heterogênea e da porosidade φ. Resultados numéricos do estudo comparativo entre a abordagem microscópica e a macroscópica são apresentados. Como resultado, correlações para o Nusselt médio para os modelos contínuo e poro-contínuo são obtidas em função do Ra modificado para cada Re.In this work is presented mixed convection heat transfer inside a lid-driven cavity heated from below and filled with heterogeneous and homogeneous porous medium. In the heterogeneous approach, the solid domain is represented by heat conductive equally spaced blocks; the fluid phase surrounds the blocks being limited by the cavity walls. The homogeneous or pore-continuum approach is characterized by the cavity porosity and permeability. Generalized mass, momentum and energy conservation equations are obtained in dimensionless form to represent both the continuum and the pore-continuum models. The numerical solution is obtained via the finite volume method. QUICK interpolation scheme is set for numerical treatment of the advection terms and SIMPLE algorithm is applied for pressure-velocity coupling. Aiming the laminar regime, the flow parameters are kept in the range of 102≤Re≤103 and 103≤Ra≤106 for both the heterogeneous and homogeneous approaches. In the tested configurations for the continuous model, 9, 16, 36, and 64 blocks are considered for each combination of Re and Ra being the microscopic porosity set as constant φ=0,64 . For the pore-continuum model the Darcy number (Da) is set according to the number of blocks in the heterogeneous cavity and the φ. Numerical results of the comparative study between the microscopic and macroscopic approaches are presented. As a result, average Nusselt number equations for the continuum and the pore continuum models as a function of Ra and Re are obtained.
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Meira, Rodrigo Esperança da Cunha Pimentel de. "Estudo do escoamento de fluidos de lei de potência e de Bingham em canal parcialmente poroso utilizando o método Lattice Boltzmann." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/2715.
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CERNNNeste trabalho, propõe-se o estudo numérico do escoamento de fluidos de lei de potência e Bingham junto à interface entre uma região livre e outra porosa (interface fluido-porosa) utilizando o método lattice Boltzmann. Para tanto, considera-se o escoamento entre placas planas e paralelas entre as quais se faz presente um meio poroso abordado de forma heterogênea (resolução espacial da ordem de grandeza dos poros), representado através de obstáculos sólidos quadrados uniformemente distribuídos na parte inferior do canal. As análises realizadas mostram o efeito dos diversos parâmetros adimensionais que descrevem o problema sobre o fator de atrito na região livre do canal. De um modo geral, constata-se que a discrepância entre os fatores de atrito na região livre do canal e para o escoamento entre placas planas e paralelas cresce com o aumento da porosidade e do número de Bingham e com as reduções do número de obstáculos que compõem o meio poroso, número de Reynolds e índice de lei de potência. Ademais, propõe-se a adaptação do modelo analítico para a representação da interface fluido- porosa para escoamento de fluido newtoniano proposto por Ochoa-Tapia e Whitaker (1995b) ao escoamento de fluido de lei de potência, verificando-se a possibilidade de incorporar o comportamento não newtoniano do fluido ao parâmetro empírico do modelo.
The goal of this work is to numerically investigate the flow of power law and Bingham fluids next to the interface between a free and a porous region (fluid-porous interface) using the lattice Boltzmann method. For this, the flow between parallel plates partially filled by a porous material is studied, with the porous medium being represented by a set of solid square obstacles uniformly distributed in lower half of the channel. Results show the influence of non-dimensional parameters in the free region friction factor. In geral, it is observed that the friction factor decreases when porosity or Bingham number are increased and number of obstacles, Reynolds number or power law index are lowered. Moreover, it is porposed the application of the fluid-porous interface model proposed by Ochoa-Tapia e Whitaker (1995b) to the flow of power law fluids by varying the stress jump coefficient with the power law index.
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Lavarda, Jairo Vinícius. "Convecção natural de fluidos de lei de potência e de Bingham em cavidade fechada preenchida com meio heterogêneo." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1306.
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CAPESVários estudos numéricos investigaram cavidades fechadas sob o efeito da convecção natural preenchidas com fluidos newtonianos generalizados (FNG) nos últimos anos pelas aplicações diretas em trocadores de calor compactos, no resfriamento de sistemas eletrônicos e na engenharia de polímeros. Neste trabalho é realizada a investigação numérica do processo de convecção natural de fluidos de lei de Potência e de Bingham em cavidades fechadas, aquecidas lateralmente e preenchidas com meios heterogêneos e bloco centrado. O meio heterogêneo é constituído de blocos sólidos, quadrados, desconectados e condutores de calor. Como parâmetros são utilizados a faixa de Rayleigh de 104 à 107, índice de potência n de 0, 6 à 1, 6, número de Bingham de 0, 5 até Bimax , sendo investigado da influência do número de Prandtl para cada modelo de fluido. Nas cavidades com meio heterogêneo são utilizadas as quantidades de blocos de 9, 16, 36 e 64, mantendo-se a razão entre a condutividade térmica do sólido e do fluido κ = 1. Para as cavidades com bloco centrado, são utilizados os tamanhos adimensionais de 0, 1 à 0, 9 com κ = 0, 1; 1 e 10. A modelagem matemática é realizada pelas equações de balanço de massa, de quantidade de movimento e de energia. As simulações são conduzidas no programa comercial ANSYS FLUENT R . Inicialmente são resolvidos problemas com fluidos newtonianos em cavidade limpa, seguida de cavidade preenchida com meio heterogêneo e posteriormente bloco centrado para validação da metodologia de solução. Na segunda etapa é realizada o estudo com os modelos de fluidos de lei de Potência e de Bingham seguindo a mesma sequência. Os resultados são apresentados na forma de linhas de corrente, isotermas e pelo número de Nusselt médio na parede quente. De maneira geral, a transferência de calor na cavidade é regida pelo número de Rayleigh, tamanho e condutividade térmica dos blocos, pelo índice de potência para o modelo de lei de Potência e do número de Bingham para o modelo de Bingham. O número de Prandtl tem grande influência nos dois modelos de fluidos. O meio heterogêneo reduz a transferência de calor na cavidade quando interfere na camada limite térmica para ambos os fluidos, sendo feita uma previsão analítica para o fluido de lei de Potência. Para bloco centrado, a interferência na camada limite com fluido de lei de Potência também foi prevista analiticamente. A transferência de calor aumentou com bloco de baixa condutividade térmica e pouca interferência e com bloco de alta condutividade térmica e grande interferência, para ambos os fluidos.
Many studies have been carried out in square enclosures with generalized Newtonian fluids with natural convection in past few years for directly applications in compact heat exchangers, cooling of electronics systems and polymeric engineering. The natural convection in square enclosures with differently heated sidewalls, filled with power-law and Bingham fluids in addition with heterogeneous medium and centered block are analyzed in this study. The heterogeneous medium are solid, square, disconnected and conducting blocks. The parameters used are the Rayleigh number in the range 104 - 107 , power index n range of 0, 6 - 1, 6, Bingham number range of 0, 5 - Bimax , being the influence of Prandtl number investigated for each fluid model. The number of blocks for heterogeneous medium are 9, 16, 36 and 64, keeping constant solid to fluid conductive ratio, κ = 1. For enclosures with centered block are used the nondimensional block size from 0, 1 to 0, 9, with solid to fluid conductive ratio in range κ = 0, 1; 1 and 10. Mathematical modeling is done by mass, momentum and energy balance equations. The solution of equations have been numerically solved in ANSYS FLUENT R software. Firstly, numerical solutions for validation with Newtonian fluids in clean enclosures are conducted, followed by enclosures with heterogeneous medium and centered block. Subsequently, numerical solutions of power-law and Bingham fluids with same enclosures configurations are conducted. The results are reported in the form of streamlines, isotherms and average Nusselt number at hot wall. In general, the heat transfer process in enclosure is governed by Rayleigh number, size and thermal conductivity of the blocks, power index n for power-law fluid and Bingham number for Bingham fluid. Both fluid models are very sensitive with Prandtl number changes. Heterogeneous medium decrease heat transfer in enclosure when affects thermal boundary layer for both fluid models. One analytical prediction was made for power-law fluid. An increase in heat transfer occurs with low thermal conductivity block and few interference and with high thermal conductivity block and great interference, for both fluids.
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"Local and global fluctuations in a porous medium." 2005. http://library.cuhk.edu.hk/record=b5896431.
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Mak Chung Ming = 多孔介質中的局部性與整體性漲落 / 麥仲明.Thesis submitted in: July 2004.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references (leaves 116-123).
Text in English; abstracts in English and Chinese.
Mak Chung Ming = Duo kong jie zhi zhong de ju bu xing yu zheng ti xing zhang luo / Mai Zhongming.
Abstract (in English) --- p.i
Abstract (in Chinese) --- p.ii
Acknowledgements --- p.iii
Table of Contents --- p.iv
List of Figures --- p.vi
List of Tables --- p.ix
Chapters
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Motivation of research on porous medium --- p.1
Chapter 1.2 --- Description of porous medium --- p.2
Chapter 1.3 --- Brief history of research of thermal convection in porous medium --- p.5
Chapter 2. --- Background --- p.7
Chapter 2.1 --- Introduction --- p.7
Chapter 2.2 --- Governing equations and parameters --- p.8
Chapter 2.3 --- Review of literature --- p.15
Chapter 2.4 --- Summary --- p.20
Chapter 3. --- Instrumentation --- p.21
Chapter 3.1 --- Experimental setup --- p.21
Chapter 3.1.1 --- Porous medium --- p.21
Chapter 3.1.2 --- Working fluid --- p.24
Chapter 3.1.3 --- Container cell --- p.25
Chapter 3.1.4 --- Top plate --- p.26
Chapter 3.1.5 --- Bottom plate --- p.28
Chapter 3.2 --- Thermistors and its calibration --- p.28
Chapter 3.3 --- Other apparatuses --- p.31
Chapter 4. --- Data analysis and results --- p.33
Chapter 4.1 --- Measurement of global heat flux --- p.33
Chapter 4.1.1 --- Heat transfer characteristic --- p.34
Chapter 4.2 --- Local temperature measurements --- p.37
Chapter 4.2.1 --- 3mm bead´ؤwater system (small cell) --- p.38
Chapter 4.2.2 --- 6mm bead´ؤwater system (small cell) --- p.44
Chapter 4.2.3 --- 6mm bead´ؤwater system (large cell) --- p.64
Chapter 4.2.4 --- 10mm bead´ؤwater system (large cell) --- p.76
Chapter 4.3 --- Correlation of the time series --- p.96
Chapter 4.4 --- Thermal pulse experiment --- p.101
Chapter 5. --- Conclusions --- p.111
Appendix --- p.114
Bibliography --- p.116
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Visser, Coert Johannes. "Modelling heat and mass flow through packed pebble beds : a heterogeneous volume-averaged approach." Diss., 2008. http://hdl.handle.net/2263/27623.
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This work details modelling buoyancy-driven viscous flow and heat transfer through heterogeneous saturated packed pebble beds via a set of volume-averaged conservation equations in which local thermal disequilibrium is accounted for. The latter refers to the two phases considered viz. solid and fluid, differing in temperature. This is effected by describing each phase with its own governing equation. Further to the aforementioned, the governing equation set is written in terms of intrinsic volume-averaged material properties that are fully variant with respect to temperature. The heterogeneous solid phase is described with a porosity field varying from 0.39 to 0.99. The intent of the stated upper bound is to explicitly model typical packed bed near-wall phenomena such as wall-channelling and pebble-wall heat transfer as true to reality as possible, while maintaining scientific rigour. The set of coupled non-linear partial differential equations is solved via a locally preconditioned artificial compressibility method, where spatial discretisation is effected with a compact finite volume edge-based discretisation method. The latter is done in the interest of accuracy. Stabilisation is effected via JST scalar-valued artificial dissipation. This is the first instance in which an artificial compressibility algorithm is applied to modelling heat and fluid flow through heterogeneous porous materials. As a result of the aforementioned, calculation of the acoustic velocities, stabilisation scaling factors and allowable time-step sizes were revised. The developed technology is demonstrated by application to the modelling of SANA test cases, i.e. natural convective flow inside a heated porous axisymmetric cavity. Predicted results are shown to be within 12% of experimental measurements in all cases, while having an average deviation of only 3%.Dissertation (MEng)--University of Pretoria, 2008.
Mechanical and Aeronautical Engineering
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Books on the topic "Compressibility Heat Fluid dynamics Porous materials"
1
Ene, Horia I. Thermal flow in porous media. Dordrecht, Holland: D. Reidel Pub. Co., 1987.
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2
Marcelo J.S. de Lemos. Turbulent Impinging Jets into Porous Materials. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012.
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3
Modelling heat and mass transfer in freezing porous media. Hauppauge, N.Y., USA: Nova Science Publishers, 2012.
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4
American Society of Mechanical Engineers. Winter Meeting. Heat transfer and flow in porous media: Presented at the Winter Annual Meeting of the American Society of Mechanical Engineers, Dallas, Texas, November 25-30, 1990. New York, N.Y: ASME, 1990.
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5
Nield, Donald A. Convection in Porous Media. 4th ed. New York, NY: Springer New York, 2013.
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6
Lemos, Marcelo J. S. de. Turbulent Impinging Jets into Porous Materials. Springer, 2012.
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7
Brondenbrener, Leonid. Modelling Heat and Mass Transfer in Freezing Porous Media. Nova Science Publishers, Incorporated, 2012.
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8
B, Sagar, U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Regulatory Applications., Analytic and Computational Research, Inc., and Center for Nuclear Waste Regulatory Analyses (Southwest Research Institute), eds. PORFLOW: A multifluid multiphase model for simulating flow, heat transfer, and mass transport in fractured porous media : user's manual, version 2.41. Washington, DC: Division of Regulatory Applications, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1993.
Find full textBook chapters on the topic "Compressibility Heat Fluid dynamics Porous materials"
1
Furbish, David Jon. "Porous Media Flows." In Fluid Physics in Geology. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195077018.003.0017.
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So far our treatment of fluid motions has not emphasized the behavior of fluids residing within porous geological materials. Let us now turn to this topic and, in doing so, make use of our insight regarding purely fluid flows. The general topic of fluid behavior within porous geological materials is an extensive one, forming the heart of such fields as groundwater hydrology, soils physics, and petroleum-reservoir dynamics. In addition, this topic is an essential ingredient in studies concerning the physical and chemical evolution of sedimentary basins, and the dynamics of accretionary prisms at convergent plate margins. In view of the breadth of these topics, the objective of this chapter is to introduce essential ingredients of fluid flow and transport within porous materials that are common to these topics. Our first task is to examine the physical basis of Darcy’s law, and to generalize this law to a form that can be used with an arbitrary orientation of the working coordinate system relative to the intrinsic coordinates of a geological unit that are associated with its anisotropic properties. We will likewise examine the basis of transport of solutes and heat in porous materials. We will then develop the equations of motion for the general case of saturated flow in a deformable medium. In this regard, several of the Example Problems highlight interactions between flow and strain of geological materials during loading, because this interaction bears on many geological processes. Examples include consolidation of sediments during loading, and responses of aquifers to loading by oceanic and Earth tides, and seismic stresses. We will concentrate on the description of diffuse flows within the interstitial pores of granular materials, as opposed to flows within materials containing dual, or multiple, pore systems such as karstic media, or media containing both interstitial and fracture porosities. We will consider unsaturated, as well as saturated, conditions. For simplicity, the subscript h is omitted from the notation of quantities such as specific discharge q and hydraulic conductivity K.
Conference papers on the topic "Compressibility Heat Fluid dynamics Porous materials"
1
Martins-Costa, Maria Laura, and Roge´rio M. Saldanha da Gama. "Forced Convection Flow Through an Unsaturated Wellbore." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41128.
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This work studies the dynamics of the filling up of a rigid cylindrical shell porous matrix by a Newtonian fluid and the heat transfer associated phenomenon. A mixture theory approach is employed to obtain a preliminary local model for nonisothermal flows through a wellbore. The mixture consists of three overlapping continuous constituents: a solid (porous medium), a liquid and an inert gas included to account for the compressibility of the mixture as a whole. Assuming the convection flow on radial direction only, a set of four nonlinear partial differential equations describes the problem. Its hydrodynamic part — a nonlinear hyperbolic system — is approximated by means of a Glimm’s scheme, combined with an operator splitting technique, while an implicit finite difference scheme is used to simulate the thermal part.
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Enright, Ryan, Cormac Eason, Tara Dalton, and Todd Salamon. "Transport in Superhydrophobic Microchannels: A Porous Modeling Approach." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32823.
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Superhydrophobic surfaces combine roughness features with low energy surfaces to create materials with substantially decreased wettability and reduced drag resistance in laminar flows. These characteristics make superhydrophobic surfaces a promising technology for reducing the flow resistance of microchannels in a variety of applications, including thermal management and biofluidics. The presence of a gas layer that is trapped within the superhydrophobic surface, and which separates the majority of the microchannel wall from the working fluid, gives rise to a low shear-stress region responsible for the observed reduction in flow resistance. Although there have been numerous experimental and computational studies of fluid flow in superhydrophobic microchannels, to our knowledge no predictive analytical model capturing the essential features of the flow has been developed for the case of post-type surface roughness. In this work we propose the use of porous flow theory to predict the behavior of the fully-developed inertia-less flow of a constant viscosity Newtonian fluid in a parallel-plate, super-hydrophobic microchannel whose roughness features are composed of a square array of posts arranged transverse to the flow. The volume-averaged Navier-Stokes (VANS) equation is used to model the flow behavior in both the open and porous regions, taking into account the presence of a recirculating gas layer and the potential for partial liquid penetration into the porous region. The fluid motion in the porous and non-porous regions is coupled by imposing boundary conditions specifying the continuity of velocity and a stress jump at the interface between the two regions. An empirical factor, known as the stress jump coefficient β, appears in the stress jump boundary condition and is shown to be correlated to the geometric properties of the porous region via a scaling law inferred from non-dimensional analysis and observed in 3D computational fluid dynamics simulations. Finally, the predictions of the model are compared with existing experimental studies.
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Sobera, M. P., C. R. Kleijn, P. Brasser, and H. E. A. van den Akker. "Multiscale CFD of the Flow, Heat and Mass Transfer Through a Porous Material With Application to Protective Garments." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3106.
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A multi-scale study of the performance of protective clothing has been performed by coupling various types of numerical simulation of flow, heat and mass transfer. At first, a detailed study of the turbulent flow at Re = 3900 around a circular cylinder, sheathed at some small distance by a porous layer, has been performed by means of Direct Numerical Simulations with a commercial unstructured finite volume based Computational Fluid Dynamics solver. This geometry is widely used in experiments to study the performance of fabric materials. From this DNS study, it was found that the flow underneath the clothing is laminar and periodic, with a velocity magnitude much smaller than the free stream velocity. Micro-scale Direct Numerical Simulations of the flow through the textile at the scale of individual fibres revealed a simple relation between textile porosity and permeability. A good agreement was found between flow and heat transfer predictions of Direct Numerical Simulations and from Reynolds Averaged simulations. From the latter, an engineering correlation for heat and mass transfer was deduced.
4
Aviles-Ramos, Cuauhtemoc, and Clifford Rudy. "Steady-State Heat Transfer Modeling of a Calorimeter Measurement Chamber." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32091.
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The steady-state heat transfer in a calorimeter measurement chamber is modeled assuming that the sample is a generic nuclear material container filled with plutonium oxide powder. The measurement chamber is composed of nine solid materials and air. The heat transfer model includes natural convection in the plutonium oxide porous matrix, natural convection in the air space on top of the plutonium oxide powder, and heat conduction in the different solid parts of the measurement chamber and the heat flux sensor. The problem is treated as a conjugate heat transfer problem defined by a system of 24 partial differential equations coupled at the interfaces of the materials that form the measurement chamber. A computational fluid dynamics software is used to generate the grid and obtain the solution. The simulation results provide estimates of operational temperatures and heat losses that are of interest in the design of calorimeters.
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Yuan, Jinliang, Guogang Yang, and Bengt Sunde´n. "CFD Approach Analysis of Chemical Reactions Coupled Convective Heat Transfer in Reformer Ducts." In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56077.
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Thermo-mechanical failure of components in a compact steam reformer is a major obstacle to bring this technology to real-life applications. The probability of material degradation and failure depends strongly on the convective heat transfer in the fuel gas flow duct and local temperature distribution in multifunctional materials. It is of significant importance to accurately predict the convective heat transfer coupled with catalytic reactions within the reformer components. In this paper, the simulation and analysis of combined chemical reactions and transport processes are conducted for a duct relevant for compact design steam reformer, which consists of a porous layer for the catalytic reforming reactions of methane, the fuel gas flow duct and solid plates. A fully three-dimensional computational fluid dynamics (CFD) approach is applied to calculate transport processes and effects of thermal conductivities of the involved multi-functional materials on convective heat transfer/temperature distributions, in terms of interface temperature gradients/heat fluxes and Nusselt numbers. The steam reformer conditions such as mass balances associated with the reactions and gas permeation to/from the porous anode are implemented in the calculation. The results show that the classic thermal boundary conditions (either constant heat flux or temperature, or combined one) may not be applicable for the interfaces between the fuel flow duct and solid plate/porous layer.
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Ho, Clifford K., and Walter Gerstle. "Terrestrial Heat Repository for Months of Storage (THERMS): A Novel Radial Thermocline System." In ASME 2021 15th International Conference on Energy Sustainability collocated with the ASME 2021 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/es2021-63066.
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Abstract This paper describes a terrestrial thermocline storage system comprised of inexpensive rock, gravel, and/or sand-like materials to store high-temperature heat for days to months. The present system seeks to overcome past challenges of thermocline storage (cost and performance) by utilizing a confined radial-based thermocline storage system that can better control the flow and temperature distribution in a bed of porous materials with one or more layers or zones of different particle sizes, materials, and injection/extraction wells. Air is used as the heat-transfer fluid, and the storage bed can be heated or “trickle charged” by flowing hot air through multiple wells during periods of low electricity demand using electrical heating or heat from a solar thermal plant. This terrestrial-based storage system can provide low-cost, large-capacity energy storage for both high- (∼400–800°C) and low- (∼100–400°C) temperature applications. Bench-scale experiments were conducted, and computational fluid dynamics (CFD) simulations were performed to verify models and improve understanding of relevant features and processes that impact the performance of the radial thermocline storage system. Sensitivity studies were performed using the CFD model to investigate the impact of the air flow rate, porosity, particle thermal conductivity, and air-to-particle heat-transfer coefficient on temperature profiles. A preliminary technoeconomic analysis was also performed to estimate the levelized cost of storage for different storage durations and discharging scenarios.
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Kisselev, Arcadii E., Gennadii V. Kobelev, Valerii F. Strizhov, and Alexander D. Vasiliev. "Debris Thermal Hydraulics Modeling of QUENCH Experiments." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89457.
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Porous debris formation and behavior in QUENCH experiments (QUENCH-02, QUENCH-03) plays a considerable role and its adequate modeling is important for thermal analysis. This work is aimed to the development of a numerical module which is able to model thermal hydraulics and heat transfer phenomena occurring during the high-temperature stage of severe accident with the formation of debris region and molten pool. The original approach for debris evolution is developed from classical principles using a set of parameters including debris porosity; average particle diameter; temperatures and mass fractions of solid, liquid and gas phases; specific interface areas between different phases; effective thermal conductivity of each phase, including radiative heat conductivity; mass and energy fluxes through the interfaces. The debris model is based on the system of continuity, momentum and energy conservation equations, which consider the dynamics of volume-averaged velocities and temperatures of fluid, solid and gaseous phases of porous debris. The different mechanisms of debris formation are considered, including degradation of fuel rods according to temperature criteria, taking into consideration some correlations between rod layers thicknesses; degradation of rod layer structure due to thermal expansion of melted materials inside intact rod cladding; debris formation due to sharp temperature drop of previously melted material due to reflood; and transition to debris of material from elements lying above. The porous debris model was implemented to best estimate numerical code RATEG/SVECHA/HEFEST developed for modeling thermal hydraulics and severe accident phenomena in a reactor. The model is used for calculation of QUENCH experiments. The results obtained by the model are compared to experimental data concerning different aspects of thermal behavior: thermal hydraulics of porous debris, radiative heat transfer in a porous medium, the generalized melting and refreezing behavior of materials, hydrogen production.