Heat Transfer Through a Porous Medium

Nield, D. A.; Bejan, Adrian

doi:10.1007/978-1-4757-3033-3_2

Cited by 12 publications

(25 citation statements)

References 91 publications

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“…where the membrane heat transfer coefficient h m is the weighted average of thermal conductivity of the membrane material and air [23], k m and k g respectively, expressed as [5]:…”

Section: Heat Transfer In Dcmdmentioning

confidence: 99%

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

et al. 2017

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Membrane distillation (MD) is an emerging technology that has a great potential for sustainable water desalination. In order to pave the way for successful commercialization of MD-based water desalination techniques, adequate and accurate dynamical models of the process are essential. This paper presents the predictive capabilities of a lumped-parameter dynamic model for direct contact membrane distillation (DCMD) and discusses the results under wide range of steady-state and dynamic conditions. Unlike previous studies, the proposed model captures the time response of the spacial temperature distribution along the flow direction. It also directly solves for the local temperatures at the membrane interfaces, which allows to accurately model and calculate local flux values along with other intrinsic variables of great influence on the process, like the temperature polarization coefficient (TPC). The proposed model is based on energy and mass conservation principles and analogy between thermal and electrical systems. Experimental data was collected to validated the steady-state and dynamic responses of the model. The obtained results shows great agreement with the experimental data. The paper discusses the results of several simulations under various conditions to optimize the DCMD process efficiency and analyze its response. This demonstrates some potential applications of the proposed model to carryout scale up and design studies.

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“…where the membrane heat transfer coefficient h m is the weighted average of thermal conductivity of the membrane material and air [23], k m and k g respectively, expressed as [5]:…”

Section: Heat Transfer In Dcmdmentioning

confidence: 99%

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

et al. 2017

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“…and conductive heat transfer by the first term of the right‐hand side. The effective thermal conductivity λ b in the porous media is evaluated by assuming that heat conduction in the solid and gas phase takes place in parallel which follows from the fifth assumption that no heat transfer occurs between the solid and gas phases

λ_{normalb} = (1 - ε) λ_{normalc} + ε λ_{normalg}

…”

Section: Modeling Approachmentioning

confidence: 99%

Simulation of biomass char gasification in a downdraft reactor for syngas production

et al. 2015

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A steady state, one-dimensional computational fluid dynamics model of wood char gasification in a downdraft reactor is presented. The model is not only based on reaction kinetics and fluid flow in the porous char bed but also on equations of heat and mass conservation. An original OpenFOAM solver is used to simulate the model and the results are found to be in good agreement with published experimental data. Next, a sensitivity analysis is performed to study the influence of reactor inlet temperature and gas composition on char conversion, bed temperature profile and syngas composition. In addition, the evolution of the complex reaction mechanisms involved in mixed atmosphere gasification is investigated, and the most suitable operating parameters for controlling syngas composition are evaluated. Our simulation results provide essential knowledge for optimizing the design and operation of downdraft gasifiers to produce syngas that meets the requirements of various biofuel applications.In all graphs, the experimental data provided by Teixeira et al. 24 are represented by triangles, and the predicted values from OPENFOAM and COMSOL 24 simulations are represented by solid and dashed lines, respectively. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

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“…A great number of applications in geophysics may be found in the books by Phillips (1991), Ingham and Pop (1998), and Nield and Bejan (1999). When the fluid slowly percolates through the pores of a macroscopically homogeneous and isotropic porous medium, the gross effect is represented by Darcy's law.…”

Section: Introductionmentioning

confidence: 99%

Hall Effect on Thermal Instability of Viscoelastic Dusty Fluid in Porous Medium

Singh¹,

Gupta²

2013

International Journal of Applied Mechanics and Engineering

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The effect of Hall currents and suspended dusty particles on the hydromagnetic stability of a compressible, electrically conducting Rivlin-Ericksen elastico viscous fluid in a porous medium is considered. Following the linearized stability theory and normal mode analysis the dispersion relation is obtained. For the case of stationary convection, Hall currents and suspended particles are found to have destabilizing effects whereas compressibility and magnetic field have stabilizing effects on the system. The medium permeability, however, has stabilizing and destabilizing effects on thermal instability in contrast to its destabilizing effect in the absence of the magnetic field. The critical Rayleigh numbers and the wave numbers of the associated disturbances for the onset of instability as stationary convection are obtained and the behavior of various parameters on critical thermal Rayleigh numbers are depicted graphically. The magnetic field, Hall currents and viscoelasticity parameter are found to introduce oscillatory modes in the systems, which did not exist in the absence of these parameters.

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Heat Transfer Through a Porous Medium

Cited by 12 publications

References 91 publications

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

Simulation of biomass char gasification in a downdraft reactor for syngas production

Hall Effect on Thermal Instability of Viscoelastic Dusty Fluid in Porous Medium

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