TY - JOUR
T1 - Influence of heat and mass transfer on the ignition and NO x formation in single droplet combustion
AU - Moesl, Klaus G.
AU - Schwing, Joachim E.
AU - Fenninger, Wolfgang J.
AU - Sattelmayer, Thomas
N1 - Funding Information:
This research is jointly supported by the German Aerospace Center (DLR) and the European Space Agency (ESA) under the contract numbers 50WM0735 and AO-99-094, respectively.
PY - 2011/8
Y1 - 2011/8
N2 - The effect of heat and mass transfer on the ignition, and in a second step on the nitrogen oxide (NO x) generation, of single burning droplets is examined in a numerical study. Spherical symmetry with no gravity and no forced convection is presumed; ambient temperature is set at 500 K, below the auto-ignition point. The essentials of a forced droplet ignition by an external energy source are introduced. Two methods are applied: heat introduction at a fixed radial position r and heat introduction at a fixed local equivalence ratio φ r. This study's distinctiveness compared to previous research is its focus on and its combination of partially pre-vaporized droplets and detailed chemistry, both being technically relevant in kerosene and diesel fuel combustion. The fuel of choice is n-decane (C10H22), and NO x production is studied exemplarily as a representative group of pollutant emissions. The conducted simulations show a decrease of NO x formation with an increase of the pre-vaporization rate Uppsi. This decrease is generally valid for both methods of heat introduction. However, results on flame stabilization and NO x production reveal a high sensitivity to parameters of the ignition model. The burning behavior during the initial stages is dominated by the ignition position. Extracting heat from the exhaust gas region of burning droplets shows no impact on the flame position nor on the relative NO x production. As a consequence, a well-founded modeling of the investigated droplet regime needs to resort to an iterative adaptation of the heat introduction parameters based on the findings of droplet burning and exhaust gas production.
AB - The effect of heat and mass transfer on the ignition, and in a second step on the nitrogen oxide (NO x) generation, of single burning droplets is examined in a numerical study. Spherical symmetry with no gravity and no forced convection is presumed; ambient temperature is set at 500 K, below the auto-ignition point. The essentials of a forced droplet ignition by an external energy source are introduced. Two methods are applied: heat introduction at a fixed radial position r and heat introduction at a fixed local equivalence ratio φ r. This study's distinctiveness compared to previous research is its focus on and its combination of partially pre-vaporized droplets and detailed chemistry, both being technically relevant in kerosene and diesel fuel combustion. The fuel of choice is n-decane (C10H22), and NO x production is studied exemplarily as a representative group of pollutant emissions. The conducted simulations show a decrease of NO x formation with an increase of the pre-vaporization rate Uppsi. This decrease is generally valid for both methods of heat introduction. However, results on flame stabilization and NO x production reveal a high sensitivity to parameters of the ignition model. The burning behavior during the initial stages is dominated by the ignition position. Extracting heat from the exhaust gas region of burning droplets shows no impact on the flame position nor on the relative NO x production. As a consequence, a well-founded modeling of the investigated droplet regime needs to resort to an iterative adaptation of the heat introduction parameters based on the findings of droplet burning and exhaust gas production.
UR - http://www.scopus.com/inward/record.url?scp=80051737056&partnerID=8YFLogxK
U2 - 10.1007/s00231-011-0863-z
DO - 10.1007/s00231-011-0863-z
M3 - Article
AN - SCOPUS:80051737056
SN - 0947-7411
VL - 47
SP - 1065
EP - 1076
JO - Heat and Mass Transfer/Waerme- und Stoffuebertragung
JF - Heat and Mass Transfer/Waerme- und Stoffuebertragung
IS - 8
ER -