Prediction of flame speed and exergy analysis of premixed flame in a heat recirculating cylindrical micro combustor

Rana, U. S.; Chakraborty, Suman; Som, S. K.

doi:10.1016/j.energy.2017.03.063

Cited by 20 publications

(5 citation statements)

References 34 publications

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“…The exergy analysis has recently been adopted in PMB combustion to improve heat management. Rana et al [ 38 ] used a cylindrical micro combustor to numerically evaluate the exergy analysis and flame speed of premixed methane-air combustion in heat recirculation. They discovered that the second law efficiency offered valuable tools in predicting combustion performance.…”

Section: Introductionmentioning

confidence: 99%

Double-Layer Micro Porous Media Burner from Lean to Rich Fuel Mixture: Analysis of Entropy Generation and Exergy Efficiency

Ismail

Abdullah

Mustafa

et al. 2021

Entropy

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Porous media burner (PMB) is widely used in a variety of practical systems, including heat exchangers, gas propulsion, reactors, and radiant burner combustion. However, thorough evaluations of the performance of the PMB based on the usefulness of entropy generation, thermal and exergy efficiency aspects are still lacking. In this work, the concept of a double-layer micro PMB with a 23 mm cylindrical shape burner was experimentally demonstrated. The PMB was constructed based on the utilization of premixed butane-air combustion which consists of an alumina and porcelain foam. The tests were designed to cover lean to rich combustion with equivalence ratios ranging from ϕ = 0.6 to ϕ = 1.2. It was found that the maximum thermal and exergy efficiency was obtained at ϕ = 1.2 while the lowest thermal and exergy efficiency was found at ϕ = 0.8. Furthermore, the findings also indicated that the total entropy generation, energy loss, and exergy destroyed yield the lowest values at ϕ = 1.0 with 0.0048 W/K, 98.084 W, and 1.456 W, respectively. These values can be stated to be the suitable operating conditions of the PMB. The findings provided useful information on the design and operation in a double-layer PMB.

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Section: Introductionmentioning

confidence: 99%

Double-Layer Micro Porous Media Burner from Lean to Rich Fuel Mixture: Analysis of Entropy Generation and Exergy Efficiency

Ismail

Abdullah

Mustafa

et al. 2021

Entropy

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“…This study revealed that the exergy destruction at outer wall is between 5-7% of inflow exergy, and the processes of heat recirculation and combustion account for the destruction of around 40-45% of the inflow exergy. Results showed that the second law efficiency of microcombustor is nearly invariant close to the value of 58% [140].…”

Section: Entropy Generation Rate In Microcombustorsmentioning

confidence: 75%

“…And third, heat recirculation was shown to result in the increase of the exergetic losses, while increases in the wall thickness, solid to fluid thermal conductivity ratio and Peclet number have similar effects [139]. Most recently, this analytical work was further expanded with the purpose of identifying the optimum condition for heat recirculation and the associated exergetic behavior of the microcombustor [140]. This study revealed that the exergy destruction at outer wall is between 5-7% of inflow exergy, and the processes of heat recirculation and combustion account for the destruction of around 40-45% of the inflow exergy.…”

Section: Entropy Generation Rate In Microcombustorsmentioning

confidence: 99%

Generation of entropy in micro thermofluidic and thermochemical energy systems-A critical review

Torabi

Karimi

Torabi

et al. 2020

International Journal of Heat and Mass Transfer

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Micro energy systems have progressed significantly over the last two decades, as has the utilization of micro thermofluidic and thermochemical systems. Several studies were conducted to analyze the thermophysical and chemical characteristics of these systems. In general, the large rates of heat and mass transfer typically encountered in these microsystems make them susceptible to significant irreversibilities and as a result, poor second-law performances. Although the understanding and modelling of entropy generation rate in microsystems is an inevitable part of their performance analyses, no reviews were found on the second law analysis, and more specifically on the entropy generation rate of micro thermal and thermochemical systems.To address this shortcoming, the current review explores the mechanisms of entropy generation rate in these micro energy systems and identifies the possible future avenues of research in this field. The existing literature on entropy generation rate in micro single and multiphase thermofluidic systems, with the inclusion of various effects such as magnetic and electric fields, nanoparticles and thermochemical reactions are reviewed in detail. The unexplored and less investigated areas such as second law analysis of micro porous systems using pore-scale modeling and entropy generation rate of airflow through microchannels with inserts are identified, and recommendations are made for future research.

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“…The optimum Reynolds number and the minimum equivalence ratio are generally consistent with the findings in this study. The differences between these computational findings and the experimental results perhaps due to the enhanced insulation and preheating that are achieved with the heat-recirculating design and the gap distance, which is considerably larger in the experiments (Rana et al, 2017). In order to fully understand these differences, more studies are required.…”

Section: Effect Of Reynolds Numbermentioning

confidence: 82%

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

Junjie¹,

Xu²

2017

AJHMT

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Combustion characteristics and stability of premixed methane-air mixtures in catalytic micro-channels is studied numerically, using CFD (computational fluid dynamics). The characteristics of the fluid mechanics are also analyzed. A two-dimensional CFD model with detailed reaction mechanisms and multicomponent transport is developed to evaluate the effect of operating conditions on the combustion stability. The laminar flow is assumed, and steady-steady simulations are performed. The fuel-lean equivalence ratio operation limit for the system is determined by the analysis of Reynolds number. The primary focus is on CFD as a means of understanding thermal management at small scales. It is shown that an appropriate choice of the flow velocity is crucial in achieving the self-sustained operation. Large gradients in temperature and species concentration are observed, despite the small scales of the system under certain conditions. The flow velocity is very important as it determines the flame location. Furthermore, the flow velocity plays a dual, competing role in the stability of the system. Low flow velocities reduce the heat generation, whereas high flow velocities reduce the convective time-scale. There is a narrow regime of flow velocities that allows self-sustained operation. When a low-power system is desired, highly insulating materials should be preferred, whereas a high-power system would favor highly conductive materials. Engineering maps that delineate combustion stability are constructed. In order to gain further insight into the combustion characteristics of the system, the optimum Reynolds number is determined. Finally, design recommendations are made.

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Prediction of flame speed and exergy analysis of premixed flame in a heat recirculating cylindrical micro combustor

Cited by 20 publications

References 34 publications

Double-Layer Micro Porous Media Burner from Lean to Rich Fuel Mixture: Analysis of Entropy Generation and Exergy Efficiency

Double-Layer Micro Porous Media Burner from Lean to Rich Fuel Mixture: Analysis of Entropy Generation and Exergy Efficiency

Generation of entropy in micro thermofluidic and thermochemical energy systems-A critical review

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

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