Routes of formation and destruction of nitrogen oxides in CH4/H2 jet flames in a hot coflow. (18th May 2015)

• Record Type: Journal Article
• Authors: Wang, F.; Li, P.; Zhang, J.; Mei, Z.; Mi, J.; Wang, J.
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 18(2015)
• Page Start: 6228
• Page End: 6242
• Publication Date: 2015-05-18
• Subjects: Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.03.047
• Languages: English
• ISSNs: 0360-3199

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">The formation/destruction mechanisms of nitric oxides (NO<sub><italic>x</italic></sub>) in CH<sub>4</sub>/H<sub>2</sub> jet flames in a hot coflow are systematically investigated by numerical modeling. All calculations use the Eddy Dissipation Concept (EDC) model coupled with GRI-Mech 2.11. The modeling is validated by the measurements of Dally et al. [Proc. Combust. Inst. 29 (2002) 1147–1154]. Dependences of the NO<sub><italic>x</italic></sub> formation/destruction routes on <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrgsw" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si1.gif" overflow="scroll" id="d13e1613" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula>, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr74p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si2.gif" overflow="scroll" id="d13e1628" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr2dd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si3.gif" overflow="scroll" id="d13e1639" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> are examined, where <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrgsw" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si1.gif" overflow="scroll" id="d13e1653" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula>, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr74p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si2.gif" overflow="scroll" id="d13e1667" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr2dd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si3.gif" overflow="scroll" id="d13e1678" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> are the coflow oxygen concentration and temperature, and the hydrogen fraction in the fuel mixture, respectively. The following is obtained.</p> <p id="abspara0015">For <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr8qz" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si4.gif" overflow="scroll" id="d13e1694" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>≤</mml:mo><mml:mn>3</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math></alternatives></inline-formula> at <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrfxg" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si5.gif" overflow="scroll" id="d13e1714" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>1300</mml:mn><mml:mspace width="0.25em" /><mml:mtext>K</mml:mtext></mml:mrow></mml:math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr8zk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si6.gif" overflow="scroll" id="d13e1732" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>12</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math></alternatives></inline-formula>, the N<sub>2</sub>O-intermediate, prompt and NNH routes are the first (≈50%), second (30%) and third (20%) contributors to the total NO emission; as <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrgsw" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si1.gif" overflow="scroll" id="d13e1755" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> is increased, the contributions of the three routes all decrease whereas that of the thermal route becomes significant. For <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrkgp" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si7.gif" overflow="scroll" id="d13e1770" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>3</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr8zk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si6.gif" overflow="scroll" id="d13e1790" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>12</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math></alternatives></inline-formula>, the N<sub>2</sub>O-intermediate route dominates the NO formation (about 90%) at <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrhgq" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si8.gif" overflow="scroll" id="d13e1813" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo><</mml:mo><mml:mn>1000</mml:mn><mml:mspace width="0.25em" /><mml:mtext>K</mml:mtext></mml:mrow></mml:math></alternatives></inline-formula>; as <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr74p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si2.gif" overflow="scroll" id="d13e1831" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> is increased from 1000 K, the importance of either the prompt, NNH, or thermal routes is enhanced. For <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrkgp" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si7.gif" overflow="scroll" id="d13e1842" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>3</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrfxg" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si5.gif" overflow="scroll" id="d13e1863" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup><mml:mo>=</mml:mo><mml:mn>1300</mml:mn><mml:mspace width="0.25em" /><mml:mtext>K</mml:mtext></mml:mrow></mml:math></alternatives></inline-formula>, as <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr2dd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si3.gif" overflow="scroll" id="d13e1881" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> is elevated, the contribution of the NNH route to the total NO production increases while those of the N<sub>2</sub>O-intermediate and prompt routes decrease. Also, in general, the reduction of <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rrgsw" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si1.gif" overflow="scroll" id="d13e1898" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula>, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr74p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si2.gif" overflow="scroll" id="d13e1912" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mtext>cof</mml:mtext></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> or <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgjj3rr2dd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si3.gif" overflow="scroll" id="d13e1923" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>Y</mml:mi><mml:mrow><mml:msub><mml:mtext>H</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mo>∗</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula>, or altogether is found to strengthen the importance of NO<sub>2</sub> to the total NO<sub><italic>x</italic></sub> emission and the NO-reburning.</p> </sec> </abstract>