Numerical simulation of the effect of diluents on NO<sub>x</sub> formation in methane and methyl formate fuels in counter flow diffusion flame

Patrick Wanjiru; Nancy Karuri; Paul Wanyeki; Paul Kioni; Josephat Tanui; Patrick Wanjiru; Nancy Karuri; Paul Wanyeki; Paul Kioni; Josephat Tanui

doi:10.3934/environsci.2020008

AIMS Environmental Science

2020, Volume 7, Issue 2: 140-152. doi: 10.3934/environsci.2020008

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Research article

Numerical simulation of the effect of diluents on NO_x formation in methane and methyl formate fuels in counter flow diffusion flame

1.
Department of Mechanical Engineering, Dedan Kimathi University of Technology, Private Bag-1014, Dedan Kimathi, Nyeri, Kenya
2.
Department of Technical Education, Dedan Kimathi University of Technology, Private Bag-1014, Dedan Kimathi, Nyeri, Kenya

Received: 07 January 2020 Accepted: 05 March 2020 Published: 12 March 2020

The increasing global demand for energy, the need to reduce green house gasses, and the depletion of fossil fuel resources have led for the need for renewable fuel sources such as biodiesel fuels. In the diesel engines, biodiesel fuels can also be used directly without comprehensive engine changes. Biodiesel relates to a diesel fuel that is based on vegetable oil or animal fat consisting of longchain of methyl, ethyl, or propyl esters. Methyl ester fuel burns more efficiently and has lower emissions of particulate matter, unburnt hydrocarbon, and carbon monoxide than fossil fuels. However, combustion of methyl ester fuel results in increased nitrogen oxides (NO_x) emissions relative to fossil fuels. This study is concerned with characterizing the formation of NO_x in the combustion of methyl formate under a counter diffusion flame. This was carried out in an Exhaust Gas Recirculation (EGR) system. Simulation of the process was done using Combustion Simulation Laboratory Software (COSILAB), and involved simulating the reactions of methyl formate fuel. The results obtained were compared to those of the methane/air diffusion flame, which is a well-characterized system. The extension validated the results obtained for the methyl formate/air diffusion flame. The reduction of NO_x was found to be 26% and 14% in methane and methyl formate diffusion flame respectively from 0% to 29.5% of EGR. Increased EGR from 0% to 29.5% increased NO_x reduction. Compared to methane/air diffusion flame, methyl formate/air diffusion flame with and without EGR had lower NO_x emission. This was found to be true when examining the amount of other metrics viz. temperature, H, OH and N radicals associated with NO_x. This showed that EGR system have an effect on NO_x formation.
- methane,
- methyl ester,
- methyl formate,
- exhaust gas recirculation (EGR),
- COSILAB
Citation: Patrick Wanjiru, Nancy Karuri, Paul Wanyeki, Paul Kioni, Josephat Tanui. Numerical simulation of the effect of diluents on NOx formation in methane and methyl formate fuels in counter flow diffusion flame[J]. AIMS Environmental Science, 2020, 7(2): 140-152. doi: 10.3934/environsci.2020008

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Abstract

The increasing global demand for energy, the need to reduce green house gasses, and the depletion of fossil fuel resources have led for the need for renewable fuel sources such as biodiesel fuels. In the diesel engines, biodiesel fuels can also be used directly without comprehensive engine changes. Biodiesel relates to a diesel fuel that is based on vegetable oil or animal fat consisting of longchain of methyl, ethyl, or propyl esters. Methyl ester fuel burns more efficiently and has lower emissions of particulate matter, unburnt hydrocarbon, and carbon monoxide than fossil fuels. However, combustion of methyl ester fuel results in increased nitrogen oxides (NO_x) emissions relative to fossil fuels. This study is concerned with characterizing the formation of NO_x in the combustion of methyl formate under a counter diffusion flame. This was carried out in an Exhaust Gas Recirculation (EGR) system. Simulation of the process was done using Combustion Simulation Laboratory Software (COSILAB), and involved simulating the reactions of methyl formate fuel. The results obtained were compared to those of the methane/air diffusion flame, which is a well-characterized system. The extension validated the results obtained for the methyl formate/air diffusion flame. The reduction of NO_x was found to be 26% and 14% in methane and methyl formate diffusion flame respectively from 0% to 29.5% of EGR. Increased EGR from 0% to 29.5% increased NO_x reduction. Compared to methane/air diffusion flame, methyl formate/air diffusion flame with and without EGR had lower NO_x emission. This was found to be true when examining the amount of other metrics viz. temperature, H, OH and N radicals associated with NO_x. This showed that EGR system have an effect on NO_x formation.

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