CFD study on stability limits of hydrogen/air premixed flames in planar micro-combustors with catalytic walls

Li, Qingqing; Wang, Jiansheng; Meng, Liang; Li, Jun; Guo, Zhaoli

doi:10.1016/j.applthermaleng.2017.04.054

Cited by 26 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To eliminate the non-essential factors in the mathematical formulation, the following assumptions are made: (1) ideal gases and incompressible flows [36]; (2) steady-state combustion [33]; (3) no Dufour and Soret effects; (4) no gas radiation; (5) no work done by pressure and viscous forces; (6) inert porous medium [33].…”

Section: Pore-scale Modelmentioning

confidence: 99%

“…However, heat transfer through the combustor wall is ignored in recent PSM numerical simulations of porous combustors [21,[24][25][26][27][28][29]. In micro-/meso-scale combustors, heat recirculation through the combustor wall is crucial to self-sustaining and stabilizing flames, confirmed by a series of free flame cases and VAM numerical simulations [30][31][32][33][34][35][36]. In Norton and Vlachos' paper [30], computational fluid dynamics simulations of methane and propane combustion were performed to study the effects of key parameters on combustion characteristics and flame stability.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Wang

et al. 2021

Applied Sciences

Self Cite

View full text Add to dashboard Cite

Inserting porous media into the micro-scale combustor space could enhance heat recirculation from the flame zone, and could thus extend the flammability limits and improve flame stability. In the context of porous micro-combustors, the pore size is comparable to the combustor characteristic length. It is insufficient to treat the porous medium as a continuum with the volume-averaged model (VAM). Therefore, a pore-scale model (PSM) is developed to consider the detailed structure of the porous media to better understand the coupling among the gas mixture, the porous media and the combustor wall. The results are systematically compared to investigate the difference in combustion characteristics and flame stability limits. A quantified study is undertaken to examine heat recirculation, including preheating and heat loss, in the porous micro-combustor using the VAM and PSM, which are beneficial for understanding the modeled differences in temperature distribution. The numerical results indicate that PSM predicts a scattered flame zone in the pore areas and gives a larger flame stability range, a lower flame temperature and peak solid matrix temperature, a higher peak wall temperature and a larger Rp-hl than a VAM counterpart. A parametric study is subsequently carried out to examine the effects of solid matrix thermal conductivity (ks) on the PSM and VAM, and then the results are analyzed briefly. It is found that for the specific configurations of porous micro-combustor considered in the present study, the PSM porous micro-combustor is more suitable for simplifying to a VAM with a larger Φ and a smaller ks, and the methods can be applied to other configurations of porous micro-combustors.

show abstract

Section: Pore-scale Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Wang

et al. 2021

Applied Sciences

Self Cite

View full text Add to dashboard Cite

show abstract

“…Karagiannidis et al 14 verified Pt catalyst can improve the conversion of methane and facilitate the production of a strong homogeneous combustion zone for propane by numerical simulation. And Li et al 15 verified that Pt catalyst can effectively inhibit radical quenching by numerical simulation in a two‐dimensional micro‐combustor model. Chen et al 16 obtained that propane‐air flame is stable in the catalytic micro‐combustor with submillimeter gap, which is much more stable than the homogeneous counterparts.…”

Section: Introductionmentioning

confidence: 97%

Catalytic combustion characteristics of CH ₄ in the micro cavity‐combustor under different types of air inlet distribution

et al. 2020

View full text Add to dashboard Cite

There are combustion difficulties and combustion instability problems in micro-scale combustion due to the size effects. Focusing on the problem of combustion instability in micro-scale, on the basis of catalytic combustion, the recirculation zone (RZ) is constructed by cavity and the effect of RZ is enhanced by gas inlet at cavity wall to keep the stability of combustion. The total conversion of CH 4 in multi-inlets channel with cavity was higher compared with single inlet channel and single inlet channel with cavity. Numerical analysis was carried out to study the effects of total gas intake quantity (TGIQ), the excess air coefficient (EAC) and the air distribution mode, respectively. With the increase of TGIQ, the area of RZ increased gradually and a third RZ was gradually formed in the cavity. When the TGIQ gradually increased to 0.1828 mg/s, the combustor temperature increased significantly and as it continued to increase, the combustor temperature had little change. The highest temperature in combustor decreased gradually and the severe reaction zone moved from the back section of the combustor to the front with the increase of EAC. Moreover, the concentration of OH in cavity increased gradually and the mass flow rate of CH 4 in cavity decreased gradually. Increasing the air volume on the back cavity wall, the high-temperature zones and concentration of OH in cavity continuously improved when the TGIQ was same. The combustion process was enhanced and the catalytic reaction was stabled. The temperature of main channel first increased and then decreased.

show abstract

“…They demonstrated that the flammability limits increased obviously when a catalyst was added into the channel. Li et al 12 simulated H 2 /air flame in a planer micro combustor with catalytic walls to study stability limits. The numerical results showed that with increasing the gap size the blow-out limit was reduced.…”

Section: Introductionmentioning

confidence: 99%

“…Li et al. 12 simulated H 2 /air flame in a planer micro combustor with catalytic walls to study stability limits. The numerical results showed that with increasing the gap size the blow-out limit was reduced.…”

Section: Introductionmentioning

confidence: 99%

A numerical study on the blow-off limit of premixed hydrogen/air flames in a cylindrical micro-combustor

Naeemi

Hashemi

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

In the current work, a numerical study on combustion of premixed H2–air in a micro-cylindrical combustor was carried out and the critical velocity of inlet flow that causes the blow-off was obtained. Furthermore, the effects the equivalence ratio, wall thickness, geometry of combustor and thermal properties of walls on the critical blow-off velocity were studied. The numerical results showed that, increasing the equivalence ratio results in higher critical blow-off velocity. A micro combustor with thicker wall had better flame stability. As the combustor dimeter is decreased the blow-off occur in lower inlet flow velocity. Higher thermal conductivity of walls increases the critical blow-off velocity. In addition, with varying heat convection coefficient (h) and emissivity coefficient [Formula: see text] of the walls from 1 to 60 W/m2.K and 0.2 to 0.8 respectively, the critical blow-off velocity is reduced and shows the importance of wall thermal properties in the design and operation of micro-combustors.

show abstract

CFD study on stability limits of hydrogen/air premixed flames in planar micro-combustors with catalytic walls

Cited by 26 publications

References 31 publications

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Catalytic combustion characteristics of CH ₄ in the micro cavity‐combustor under different types of air inlet distribution

A numerical study on the blow-off limit of premixed hydrogen/air flames in a cylindrical micro-combustor

Contact Info

Product

Resources

About

CFD study on stability limits of hydrogen/air premixed flames in planar micro-combustors with catalytic walls

Cited by 26 publications

References 31 publications

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres: Pore-Scale vs. Volume-Averaged Models

Catalytic combustion characteristics of CH 4 in the micro cavity‐combustor under different types of air inlet distribution

A numerical study on the blow-off limit of premixed hydrogen/air flames in a cylindrical micro-combustor

Contact Info

Product

Resources

About

Catalytic combustion characteristics of CH ₄ in the micro cavity‐combustor under different types of air inlet distribution