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A study of the local entropy generation rate in a porous media burner

Mohammadi I., Esfahani J. A., Kim K. C.

Archives of Mechanics

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2020

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Vol. 72, nr 3

257--279

EN

In this paper, the work and performance of the premixed methane-air porous axisymmetrical burner have firstly been simulated numerically using the CFD tools. For this purpose the set of governing equations has been enriched by an additional energy equation in porous solid, and the chemical species transport has been extended onto the multi-step mechanism (GRI-2-11). This numerical model has been verified on the base of available benchmark experiments. Next, we have studied the local entropy generation problem taking into account not only classical contributions like viscous and turbulent dissipation but also, the porous combustion of gases. The results showed that the greatest portion of entropy generation in the porous medium burner is related to chemical reactions, followed by heat transfer, mass diffusion (mixing) and friction (viscous dissipation), respectively. According to the results, as the excess air ratio increases, the local entropy generation rate due to heat transfer and friction increases and the local entropy generation rate due to chemical reactions is decreased. Also, by increasing the volumetric heat transfer coefficient, the local entropy generation rate due to heat transfer decreases and the local entropy generation rate due to friction and chemical reactions increases. Also, the local entropy generation rate due to mixing does not show a significant change with the changing excess air ratio and volumetric heat transfer coefficient.

2

The analysis of certain features of working process of internal combustion engine that works on biogas from disposal sites

Dykun Taras, Haieva Lubov, Kozak Fedir, Demianchuk Yaroslav

Journal of New Technologies in Environmental Science

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2019

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Vol. 3, nr 4

179--185

EN

The importance of providing humankind with cheap energy through alternative ways has significantly increased in recent years. One of the areas is the production and usage of biogas. Nowadays, the potential of LCV gases is poorly implemented. These gases are produced in large quantities by agriculture and industry. The number of existing domestic installations for the disposal of this gas is insignificant, although in most developed countries there are hundreds and thousands of such units. One of the most promising sources of energy is the biogas from disposal sites, which is now polluting the atmosphere or is burned in flares. Another direction of biogas usage as a fuel in internal combustion automobile engines is also lowly developed. Because of the instability of the biogas composition, the working process of the engines has certain features that should be taken into account. In particular, an important criterion that affects the composition and, accordingly, the toxicity of the exhaust gases of the engines, is the excess air ratio for the fuel mixture.

3

The analysis of certain features of working process of internal combustion engine that works on biogas from disposal sites

Dykun Taras, Haieva Lubov, Kozak Fedir, Demianchuk Yaroslav

Journal of New Technologies in Environmental Science

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2019

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Vol. 3, nr 1

20--29

EN

The importance of providing humankind with cheap energy through alternative ways has significantly increased in recent years. One of the areas is the production and usage of biogas. Nowadays, the potential of LCV gases is poorly implemented. These gases are produced in large quantities by agriculture and industry. The number of existing domestic installations for the disposal of this gas is insignificant, although in most developed countries there are hundreds and thousands of such units. One of the most promising sources of energy is the biogas from disposal sites, which is now polluting the atmosphere or is burned in flares. Another direction of biogas usage as a fuel in internal combustion automobile engines is also lowly developed. Because of the instability of the biogas composition, the working process of the engines has certain features that should be taken into account in particular, an important criterion that affects the composition and, accordingly, the toxicity of the exhaust gases of the engines, is the excess air ratio for the fuel mixture.