The infrared thermograph observation of a porous medium assisted catalyst packed-bed under excess enthalpy reforming

2014 ◽  
Vol 39 (32) ◽  
pp. 18612-18617 ◽  
Author(s):  
Ming-Pin Lai ◽  
Rong-Fang Horng ◽  
Chen-Yu Chen ◽  
Wei-Hsiang Lai
Keyword(s):  
Porous Medium ◽  
Excess Enthalpy ◽  
Packed Bed ◽  
Infrared Thermograph

Numerical Simulation of Direct Injection Engine With Using Porous Medium

2012 ◽  
Author(s):  
Arash Mohammadi ◽  
Ali Jazayeri ◽  
Masoud Ziabasharhagh
Keyword(s):  
Porous Medium ◽  
Direct Injection ◽  
Combustion Process ◽  
Packed Bed ◽  
Published Data ◽  
Mixture Formation ◽  
Flammability Limits ◽  
Ic Engine ◽  
Engine Simulation ◽  
Wide Range

Porous media (PM) has interesting advantages in compared with free flame combustion due to the higher burning rates, the increased power range, the extension of the lean flammability limits, and the low emissions of pollutants. Future clean internal combustion (IC) engines should have had minimum emissions level (for both gaseous and particulate matter) under possible lowest fuel consumption permitted in a wide range of speed, loads and having good transient response. These parameters strongly depend on mixture formation and combustion processes which are difficult to be controlled in a conventional engine. This may be achieved by realization of homogeneous combustion process in engine. This paper deals with the simulation of direct injection IC engine equipped with a chemically inert PM, with cylindrical geometry to homogenize and stabilize the combustion of engine. A 3D numerical model for PM engine is presented in this study based on a modified version of the KIVA-3V code. Due to lack of any published data for PM engines, numerical results of thermal and combustion wave propagation in a porous medium are compared with experimental data of lean methane-air mixture under filtration in packed bed and very good agreement is seen. For PM engine simulation methane as a fuel is injected directly inside hot PM that is assumed, mounted in cylinder head. Lean mixture is formed and volumetric combustion occurs in PM and in-cylinder. Mixture formation, pressure and temperature distribution in both phases of PM and in-cylinder fluid with the production of pollutants CO and NO and also effects of injection time in the closed part of the cycle are studied.

Dry autothermal reforming from biomass derived gas under excess enthalpy with porous medium

2012 ◽  
Vol 217 ◽  
pp. 407-416 ◽  
Author(s):  
Ming-Pin Lai ◽  
Wei-Hsiang Lai ◽  
Rong-Fang Horng
Keyword(s):  
Porous Medium ◽  
Excess Enthalpy ◽  
Autothermal Reforming

First Numerical Evaluation of the Thermal Performance of a Tubular Receiver Equipped With Raschig Rings for CSP Applications

2021 ◽  
Author(s):  
Hossein Ebadi ◽  
Andrea Allio ◽  
Antonio Cammi ◽  
Laura Savoldi
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Numerical Evaluation ◽  
Porous Metal ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Enhance Heat Transfer ◽  
The Cost ◽  
First Time ◽  
Asymmetric Heating

Abstract Porous media are typically capable to enhance heat transfer, at the cost of an increase of the pressure drop, mainly in view of the huge increase in the surface wetted by the fluid. In this work, a tubular receiver for CSP applications, partly filled with a porous medium constituted by a packed bed of copper Raschig Rings is investigated for the first time. The analysis, carried out numerically, aims at studying in detail the mechanisms of the heat transfer from the wall to the gaseous heat transfer fluid (air) through the porous metal matrix in symmetric and asymmetric heating conditions. The computed results are compared to what occurs in a smooth tube subjected to the same heating, to check the increase in the heat transfer. The investigation carried out in this work represents the first step in the optimization of the porous medium structure inside the tubular receiver.

Thermal Radiation in a Packed Bed With Internal Heat Generation

2008 ◽  
Author(s):  
Jaap E. Hoffmann
Keyword(s):  
Porous Medium ◽  
Thermal Radiation ◽  
Heat Generation ◽  
Effective Conductivity ◽  
Internal Heat ◽  
Packed Bed ◽  
Internal Heat Generation ◽  
Scattering Coefficients ◽  
Fluid Properties ◽  
Forced Cooling

Thermal radiation and conduction are the main modes of heat transfer in a packed bed with internal heat generation during a loss of forced cooling incident. Due to the large number of spheres, the only feasible way of treating the bed in Computational Fluid Dynamics is through a porous medium approach. Traditionally, CFD treats a porous medium as a fluid zone, whilst fluid properties are adjusted to account for the presence of the solids. In this work, the bed is treated as a gray gass, emitting and absorbing thermal radiation at the solid temperature. A unit cell approach is used to determine the absorption and scattering coefficients. This approach prevents direct radiation between surfaces on opposite sides of the bed, but allows the free surface of the bed to exchange radiation with surrounding structures. Results generated with the proposed model were compared to modelling results using an effective conductivity (Zehner-Schlu¨nder model [1]) to combine the contributions of conduction and radiation.

Mobilization of Crude Oil in Porous Media With Oil-Soluble Surfactant Delivered by Hydrosoluble Micelles

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Chike G. Ezeh ◽  
Yufei Duan ◽  
Riccardo Rausa ◽  
Kyriakos D. Papadopoulos
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Crude Oil ◽  
Oil Recovery ◽  
Sodium Dodecyl ◽  
Packed Bed ◽  
White Pixel ◽  
Soluble Surfactants ◽  
Soluble Surfactant ◽  
Random Porous Medium

In this work, an oil-soluble surfactant was studied to enhance crude oil mobilization in a cryolite-packed miniature bed. The cryolite packed bed provided a transparent, random porous medium for observation at the microscopic level. In the first part of the paper, oil-soluble surfactants, Span 80 and Eni-surfactant (ES), were dissolved directly into the crude oil. The porous medium was imbued with the crude oil (containing the surfactants), and de-ionized water was the flooding phase; in this experiment, the system containing ES had the best performance. Subsequently, sodium dodecyl sulfate (SDS), a hydrosoluble surfactant, was used to solubilize the ES, with the SDS acting as a carrier for the ES to the contaminated porous media. Finally, the SDS/ES micellar solutions were used in oil-removal tests on the packed bed. Grayscale image analysis was used to quantify the oil recovery effectiveness for the flooding experiments by measuring the white pixel percentage in the packed bed images. The SDS/ES flooding mixture had a better performance than the SDS alone.

Laboratory Studies of Microscopic Dispersion Phenomena

1962 ◽  
Vol 2 (01) ◽  
pp. 1-8 ◽  
Author(s):  
R.J. Blackwell
Keyword(s):  
Porous Medium ◽  
Molecular Diffusion ◽  
Fixed Bed ◽  
Packed Bed ◽  
Oil Reservoirs ◽  
Fluid Mixing ◽  
Dispersion Coefficients ◽  
Mixing Processes ◽  
Molecular Diffusivity ◽  
Fixed Bed Reactors

Abstract This paper presents the results of a laboratory investigation of the process by which one fluid is displaced from a porous medium by a second fluid which is miscible with the first. The study included investigations of the microscopic mixing processes and of the gross displacement behavior. The results of this study are useful in scaling small bench-scale models or reactors to represent larger systems such as oil reservoirs or large, fixed bed reactors. Mixing in both the direction of flow and perpendicular to the direction of flow was measured in sand-packed columns. Dispersion coefficients were calculated from data obtained over a range of rates for various fluid pairs and sand-grain sizes. The data are presented by plotting the ratios of the dispersion coefficients divided by the molecular diffusivity vs a dimensionless parameter relating the forward transport by convection to lateral transport by diffusion. It was found that both longitudinal and lateral mixing are governed by molecular diffusion at low rates and by convection at high rates. At high rates, however, the lateral dispersion coefficients are about 1/24th those in the longitudinal direction. The ratio of lateral to longitudinal dispersion coefficients is compared with that predicted by various mathematical models of the pore system in a packed bed. The use of dispersion coefficients in scaling laboratory models to represent solvent floods in oil reservoirs is discussed briefly. Introduction The physical processes involved in the displacement of one fluid from a porous medium by a second fluid which is miscible with the first are fundamentally important in many diverse fields. For example, chemical engineers have been particularly concerned with the relationship of such fundamental aspects of displacement processes as the distribution of heat and mass, and the effect of fluid mixing on reactor efficiency. The specific problem of fluid mixing in fixed bed reactors has been investigated by Bernard and Wilhelm and others. Because high reactor efficiencies often require turbulent motion of the fluids within the individual flow channels of the porous medium, the emphasis in most of these studies has centered on fluid mixing in the turbulent or almost turbulent flow regimes. The mixing between miscible fluids in the laminar flow regime at very low Reynold's numbers is of particular interest in the field of and in recovery of oil.

Thermal Stability of Binary Gas Mixtures in a Porous Medium

1975 ◽  
Vol 97 (3) ◽  
pp. 378-381 ◽  
Author(s):  
M. L. Lawson ◽  
Wen-Jei Yang
Keyword(s):  
Porous Medium ◽  
Thermal Instability ◽  
Critical Rayleigh Number ◽  
Packed Bed ◽  
Horizontal Layer ◽  
Gas Mixture ◽  
Binary Gas Mixture ◽  
Steel Balls ◽  
Thermal Stability Of ◽  
Different Molecular Weight

Thermal instability of a thin horizontal layer of binary gas mixture subject to an adverse temperature gradient in a porous medium is experimentally determined by applying the Schmidt-Milverton principle for detecting the onset of convective currents. The binary gas mixture consists of helium and nitrogen gases at various composition, while a packed bed of tiny steel balls constitutes the porous medium. It is disclosed that the critical Rayleigh number for pure gas is lowered by the presence of another species of different molecular weight and has a minimum value at a certain composition of the binary mixture.

scholarly journals Waterflooding of Surfactant and Polymer Solutions in a Porous Media Micromodel

2018 ◽  
Author(s):  
Hsiang-Lan Yeh ◽  
Jaime J. Juárez
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Image Analysis ◽  
Inverse Analysis ◽  
Silicone Oil ◽  
Water Saturation ◽  
Saturated Porous Medium ◽  
Sodium Dodecyl ◽  
Packed Bed ◽  
Video Data

In this study, we examine microscale waterflooding in a randomly close-packed porous medium. Three different porosities are prepared in a microfluidic platform and saturated with silicone oil. Optical video fluorescence microscopy is used to track the water front as it flows through the porous packed bed. The degree of water saturation is compared to water containing two different types of chemical modifiers, sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP), with water in the absence of a surfactant used as a control. Image analysis of our video data yield saturation curves and calculate fractal dimension, which we use to identify how morphology changes the way an invading water phase moves through the porous media. An inverse analysis based on the implicit pressure explicit saturation (IMPES) simulation technique uses mobility ratio as an adjustable parameter to fit our experimental saturation curves. The results from our inverse analysis combined with our image analysis show that this platform can be used to evaluate the effectiveness of surfactants or polymers as additives for enhancing the transport of water through an oil-saturated porous medium.

scholarly journals Numerical analysis of forced convection heat transfer from two tandem circular cylinders embedded in a porous medium

2017 ◽  
Vol 21 (5) ◽  
pp. 2117-2128
Author(s):  
Habib-Ollah Sayehvand ◽  
Khalili Dehkordi ◽  
Parsa Basiri
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Medium ◽  
Numerical Analysis ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Packed Bed ◽  
Wall Heat Flux ◽  
Circular Cylinders ◽  
Convection Heat

Study the heat and mass transfer in packed bed heat exchangers particularly in nuclear application is subject of many new researches. In this paper numerical analysis of forced convection heat transfer from two tandem circular cylinders embedded in a packed bed, which is made of spherical aluminum particles, is investigated in laminar flow. The porous medium increases the overall heat absorbed from two cylinders and cooling effect but increases the pressure drop, significantly. Also, the effect of increase the horizontal distance between two tandem circular cylinders on flow pattern and heat transfer is investigated. For the empty channel, the total wall heat flux in very small distances have a minimum due to generation of closed vortex region and for longer distances, by increases the distance between two tandem cylinder, the total wall heat flux increases. It is shown that for two circular cylinders embedded in the packed bed, the total wall heat fluxes from two cylinders and the fluid outlet temperature increase to a maximum quantity and then decrease with negative gradient. Also, the quantities of the empty channel are too smaller than the amounts of porous medium.

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