Experimental investigation on low velocity filtration combustion in porous packed bed using gaseous and liquid fuels

Experimental and numerical studies were conducted to determine the combustion characteristics of gas diffusion combustion in a porous combustor packed with 2.5 mm or 3.5 mm alumina pellets, special attention being focused on the effect of packed bed height ( h ) on combustion, NO and CO emissions. The pollutant emission of diffusion filtration combustion is studied with different packed bed lengths in the range of 40 mm ≤ h ≤ 240 mm, fixed excess air ratio of 1.88 and fixed gas inlet velocity of 0.06 m s −1 . Results show that both immersed and surface flames coexist in the combustor. Although porous media enhance the mixing and diffusion processes, the diffusion flame shape is still observed from the side and top views of the combustor, and the diffusion filtration retains properties of diffusion combustion. The immersed flame is always observed with increase in h , whereas the height of surface flame decreases. The NO emission decreases sharply when h is increased from 40 mm to 120 mm. However, the NO emission decreases slightly when h > 120 mm. In the investigated range of h , it is shown that h has a significant influence on the CO emission, an increase in h leading to a constant increase in CO for the combustors packed with 2.5 mm or 3.5 mm pellets. The maximum CO emission is 662 ppm and the minimum value is 67 ppm. In the scope of this study, the temperature on the external wall of the combustor reaches 434–513°C.

show abstract

“…Studies by Shi et al . [14,15] and others show that the flame height was mainly controlled by the fuel diffusion rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical studies on combustion characteristics of N ₂ -diluted CH ₄ and O ₂ diffusion combustion in a packed bed

Shi

Mao

et al. 2019

R. Soc. open sci.

View full text Add to dashboard Cite

show abstract

“…Thus, collecting all these terms, the ensemble average in eq. (13) for the deposition profile can be computed explicitly as (see Appendix B for the full derivation),…”

Section: B Ensemble Averagementioning

confidence: 99%

“…This complexity plays a critical role in natural and engineered processes such as groundwater contamination and remediation [9,10], water infiltration in soils [11] and geologic carbon sequestration [12]. Porous materials represent excellent filters since they are characterized by very large surfaces compared to their volumes [7] and, thus, they are often used as filtration systems [13]. However, pore-scale fluctuations in the medium, flow and deposition properties are represented in the classical Darcy scale colloid filtration theory (CFT) by average quantities like porosity φ, the Darcy velocity q and filtration rate k [7].…”

Section: Introductionmentioning

confidence: 99%

Stochastic model for filtration by porous materials

2019

View full text Add to dashboard Cite

The transport of colloids in porous media is governed by deposition on solid surfaces and porescale flow variability. Classical approaches, like the colloid filtration theory (CFT), do not capture the behaviors observed experimentally, such as non-exponential steady state deposition profiles and heavy tailed arrival time distributions. In the framework of CFT a key assumption is that the colloid attachment rate k is constant and empirically estimated by a posteriori macroscopic data fitting. We propose a stochastic model that explicitly accounts for variability of the pore-scale transport and attachment properties. Colloidal motion is modeled as a sequence of displacements whose velocity and extension are statistically distributed. Colloidal depositions are modeled as random events whose statistics are determined by flow velocity, pore size and attachment rate. The resulting deposition profiles are in general non-exponential and can be predicted based on the disorder distributions.

show abstract

“…Flow inside a porous medium finds many applications in natural and engineering systems. Subsurface flows,() erosion,() fuel cells, and filtration systems() are a few examples of physical processes that are governed by low Reynolds number porous media flow. Accurately resolving such flows is essential for modelling transport, mixing,() anomalous diffusion,() breakthrough curves, carbon dioxide sequestration,() uncertainty quantification of pore‐scale simulations,() chemical reactions,() and many other applications.…”

Section: Introductionmentioning

confidence: 99%

An efficient preconditioner for the fast simulation of a 2D stokes flow in porous media

Quaife

Coulier

Darve

2017

Numerical Meth Engineering

View full text Add to dashboard Cite

Summary We consider an efficient preconditioner for a boundary integral equation (BIE) formulation of the two‐dimensional Stokes equations in porous media. While BIEs are well‐suited for resolving the complex porous geometry, they lead to a dense linear system of equations that is computationally expensive to solve for large problems. This expense is further amplified when a significant number of iterations is required in an iterative Krylov solver such as generalized minimial residual method (GMRES). In this paper, we apply a fast inexact direct solver, the inverse fast multipole method, as an efficient preconditioner for GMRES. This solver is based on the framework of H2‐matrices and uses low‐rank compressions to approximate certain matrix blocks. It has a tunable accuracy ε and a computational cost that scales as scriptOfalse(N2ptnormallnormalonormalg21false/εfalse). We discuss various numerical benchmarks that validate the accuracy and confirm the efficiency of the proposed method. We demonstrate with several types of boundary conditions that the preconditioner is capable of significantly accelerating the convergence of GMRES when compared to a simple block‐diagonal preconditioner, especially for pipe flow problems involving many pores.

show abstract

Experimental investigation on low velocity filtration combustion in porous packed bed using gaseous and liquid fuels

Cited by 28 publications

References 24 publications

Experimental and numerical studies on combustion characteristics of N ₂ -diluted CH ₄ and O ₂ diffusion combustion in a packed bed

Experimental and numerical studies on combustion characteristics of N ₂ -diluted CH ₄ and O ₂ diffusion combustion in a packed bed

Stochastic model for filtration by porous materials

An efficient preconditioner for the fast simulation of a 2D stokes flow in porous media

Contact Info

Product

Resources

About

Experimental investigation on low velocity filtration combustion in porous packed bed using gaseous and liquid fuels

Cited by 28 publications

References 24 publications

Experimental and numerical studies on combustion characteristics of N 2 -diluted CH 4 and O 2 diffusion combustion in a packed bed

Experimental and numerical studies on combustion characteristics of N 2 -diluted CH 4 and O 2 diffusion combustion in a packed bed

Stochastic model for filtration by porous materials

An efficient preconditioner for the fast simulation of a 2D stokes flow in porous media

Contact Info

Product

Resources

About

Experimental and numerical studies on combustion characteristics of N ₂ -diluted CH ₄ and O ₂ diffusion combustion in a packed bed

Experimental and numerical studies on combustion characteristics of N ₂ -diluted CH ₄ and O ₂ diffusion combustion in a packed bed