Optimal reactor dimensions for homogeneous combustion in small channels

Kaisare, Niket S.; Vlachos, Dionisios G.

doi:10.1016/j.cattod.2006.07.036

Cited by 103 publications

(56 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the wall serves a competing role in flame stability, walls transfer heat upstream for ignition of the cold incoming gases but at the same time are responsible for heat losses. This is consistent with homogeneous micro-combustors (Kaisare et al, 2007a;Norton et al, 2003). The transition in the wall role is also demarcated at the crossover between the wall and bulk gas temperatures.…”

Section: Computation Schemesupporting

confidence: 83%

“…However, the wall thermal conductivity has little impact on the extinction limit and conversion. The former is similar to homogeneous micro-combustors in which the wall thermal conductivity has a relatively weaker effect on the extinction limit (Kaisare et al, 2007a;Norton et al, 2003). For both fuels, materials with higher wall thermal conductivities result in lower maximum wall temperatures.…”

Section: Effect Of Equivalence Ratiomentioning

confidence: 90%

“…As a result, higher wall temperatures are observed, compared to the experimental data reported in literatures (Federici et al, 2006;Merotto et al, 2016). It has been found that the thermal properties of materials of construction play a vital role in the overall thermal stability of homogeneous micro-combustors, as the combustor walls are responsible for the majority of the upstream heat transfer as well as the external heat losses (Kaisare et al, 2007a;Norton et al, 2003). While homogeneous micro-combustors are feasible to operate, their operation is restrictive.…”

Section: Combustion Characteristics At the Micro-scalementioning

confidence: 94%

“…Improvements over a single micro-channel used here are expected, for example, by heat recirculation, but are beyond the scope of present work. Furthermore, the temperatures are lower than those of homogeneous counterparts (Kaisare et al, 2007a;Norton et al, 2003), which could ensure material stability without hot spots, simplify packaging, and eliminate the possibility of thermal nitrogen oxides formation. …”

Section: Combustion Characteristics At the Micro-scalementioning

confidence: 99%

“…At the extinction limit, the ratio of heat losses to the total heat generated is high. Overall, for the same channel size, catalytic microcombustors exhibit much lower temperatures and a wider auto-thermal regime of operation than their homogeneous counterparts (Kaisare et al, 2007a;Norton et al, 2003). Despite the well-known mass transfer limitations of catalytic combustion and the small length of the microchannel, nearly complete conversion of methane is achieved at high equivalence ratios, which is a requirement for high efficiency microsystems.…”

Section: Effect Of Equivalence Ratiomentioning

confidence: 99%

See 4 more Smart Citations

Computational Fluid Dynamics Simulation of the Thermal Uniformity in Catalytic Micro-Combustors

Chen¹,

Song²,

Xu³

2017

Frontiers in Heat and Mass Transfer

View full text Add to dashboard Cite

The combustion and heat transfer characteristics of hydrogen-air or methane-air mixtures in catalytic micro-combustors were studied numerically to assess the impact of wall thermal properties and key operation parameters on the thermal uniformity. A two-dimensional computational fluid dynamics (CFD) model was developed with detailed hetero-/homogeneous chemistry, heat conduction within the solid wall, surface radiation heat transfer, and external heat losses. Parametric studies were carried out to investigate the effect of wall thermal conductivity, feed composition, and flow rate on the thermal uniformity during highly exothermic catalytic reactions. Comparisons of hydrogen-with methane-air systems were made. Based on these insights, an overall energy balance analysis was performed in terms of enthalpy loss. It was shown that the wall thermal properties strongly affect the thermal uniformity, but little impact on the extinction limit and conversion. The feed composition and flow rate have a significant impact on the operating temperature, but only a moderate effect on the thermal uniformity. Most of the enthalpy released by the exothermic reaction is lost to the surroundings under certain conditions, although this energy exchange becomes less efficient as the flow rate increases. This feature is beneficial for heat-exchanger applications.

show abstract

Section: Computation Schemesupporting

confidence: 83%

Section: Effect Of Equivalence Ratiomentioning

confidence: 90%