Experimental and Modeling Study of C1 to C3 Hydrocarbon Ignition in the Presence of Nitric Oxide

2017 ◽  
Author(s):  
Ponnuthurai Gokulakrishnan ◽  
Casey C. Fuller ◽  
Michael S. Klassen
Keyword(s):  
Nitric Oxide ◽  
Natural Gas ◽  
Flow Reactor ◽  
Critical Role ◽  
Hydrocarbon Fuel ◽  
Kinetic Mechanism ◽  
Jet Fuels ◽  
Gas Recirculation ◽  
Hydrocarbon Ignition ◽  
Fuel Components

Nitric oxide produced during combustion will be present in vitiated air used in many devices with exhaust gas recirculation. An experimental and modeling investigation of the effect of nitric oxide on the ignition of C1 to C3 hydrocarbon fuels, namely, CH4, C2H4, C2H6 and C3H6, is presented. These molecules are important intermediate species generated during the decomposition of long-chain hydrocarbon fuel components typically present in jet fuels. Moreover, CH4 and C2H6 are major components of natural gas fuels. Although the interaction between NOx and CH4 has been studied extensively, limited experimental work is reported on C2H4, C2H6 and C3H6. NOx, even in very low concentrations, has previously been shown to effectively enhance the ignition of CH4. As a continuation of previous work with C3H8, ignition delay time measurements were obtained using a flow reactor facility with the alkanes (CH4 and C2H6) and olefins (C2H4 and C3H6) at 900 K and 950 K temperatures with 15 mole% and 21 mole% O2. Based on the experimental data, the overall effectiveness of NO in promoting ignition is found to be: CH4 > C3H6 > C3H8 > C2H6 > C2H4. CSE’s detailed kinetic mechanism, developed for natural gas fuel components, is used for model predictions as well as for sensitivity and species flux analyses. As expected, the reaction between HO2 and NO plays a critical role in promoting the ignition by generating the OH radical while converting NO into NO2. In addition, various important fuel-dependent reaction pathways that promote the ignition of these fuels are identified. H-atom abstraction by NO2 has significant contribution to the ignition of C2H4, and C2H6 whereas the reaction between NO2 and allyl radical (aC3H5) is an important route for the ignition of C3H6.

scholarly journals Experimental and Modeling Study of C1–C3 Hydrocarbon Ignition in the Presence of Nitric Oxide

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Ponnuthurai Gokulakrishnan ◽  
Casey C. Fuller ◽  
Michael S. Klassen
Keyword(s):  
Nitric Oxide ◽  
Flow Reactor ◽  
Critical Role ◽  
Hydrocarbon Fuel ◽  
Kinetic Mechanism ◽  
Jet Fuels ◽  
Model Predictions ◽  
Important Intermediate ◽  
Hydrocarbon Ignition ◽  
Detailed Kinetic Mechanism

Nitric oxide (NO) produced during combustion will be present in vitiated air used in many devices. An experimental and modeling investigation of the effect of NO on the ignition of C1–C3 hydrocarbon fuels, namely, CH4, C2H4, C2H6, and C3H6, is presented. These molecules are important intermediate species generated during the decomposition of long-chain hydrocarbon fuel components typically present in jet fuels. Moreover, CH4 and C2H6 are major components of natural gas fuels. Although the interaction between NOx and CH4 has been studied extensively, limited experimental work is reported on C2H4, C2H6, and C3H6. As a continuation of previous work with C3H8, ignition delay time (IDT) measurements were obtained using a flow reactor facility with the alkanes (CH4 and C2H6) and olefins (C2H4 and C3H6) at 900 K and 950 K temperatures with 15 mole% and 21 mole% O2. Based on the experimental data, the overall effectiveness of NO in promoting ignition is found to be: CH4 > C3H6 > C3H8 > C2H6 > C2H4. A detailed kinetic mechanism is used for model predictions as well as for reaction path analysis. The reaction between HO2 and NO plays a critical role in promoting the ignition by generating the OH radical. In addition, various important fuel-dependent reaction pathways also promote the ignition. H-atom abstraction by NO2 has significant contribution to the ignition of C2H4 and C2H6, whereas the reaction between NO2 and allyl radical (aC3H5) is an important route for the ignition of C3H6.

Ignition Characteristics of a Fischer-Tropsch Synthetic Jet Fuel

2008 ◽  
Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Kinetic Mechanism ◽  
Jet Fuel ◽  
Synthetic Jet ◽  
Jet Fuels ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition Characteristics

Ignition delay times of a “real” synthetic jet fuel (S8) were measured using an atmospheric pressure flow reactor facility. Experiments were performed between 900 K and 1200 K at equivalence ratios from 0.5 to 1.5. Ignition delay time measurements were also performed with JP8 fuel for comparison. Liquid fuel was prevaporized to gaseous form in a preheated nitrogen environment before mixing with air in the premixing section, located at the entrance to the test section of the flow reactor. The experimental data show shorter ignition delay times for S8 fuel than for JP8 due to the absence of aromatic components in S8 fuel. However, the ignition delay time measurements indicate higher overall activation energy for S8 fuel than for JP8. A detailed surrogate kinetic model for S8 was developed by validating against the ignition delay times obtained in the present work. The chemical composition of S8 used in the experiments consisted of 99.7 vol% paraffins of which approximately 80 vol% was iso-paraffins and 20% n-paraffins. The detailed kinetic mechanism developed in the current work included n-decane and iso-octane as the surrogate components to model ignition characteristics of synthetic jet fuels. The detailed surrogate kinetic model has approximately 700 species and 2000 reactions. This kinetic mechanism represents a five-component surrogate mixture to model generic kerosene-type jets fuels, namely, n-decane (for n-paraffins), iso-octane (for iso-paraffins), n-propylcyclohexane (for naphthenes), n-propylbenzene (for aromatics) and decene (for olefins). The sensitivity of iso-paraffins on jet fuel ignition delay times was investigated using the detailed kinetic model. The amount of iso-paraffins present in the jet fuel has little effect on the ignition delay times in the high temperature oxidation regime. However, the presence of iso-paraffins in synthetic jet fuels can increase the ignition delay times by two orders of magnitude in the negative temperature (NTC) region between 700 K and 900 K, typical gas turbine conditions. This feature can have a favorable impact on preventing flashback caused by the premature autoignition of liquid fuels in lean premixed prevaporized (LPP) combustion systems.

A critical role of iNOS-derived Nitric Oxide (NO) and progesterone in implantation

1998 ◽  
Vol 5 (1) ◽  
pp. 115A-115A
Author(s):  
K CHWALISZ ◽  
E WINTERHAGER ◽  
T THIENEL ◽  
R GARFIELD
Keyword(s):  
Nitric Oxide ◽  
Critical Role

Developmental changes in nitric oxide synthase isoform expression and nitric oxide production in fetal baboon lung

2002 ◽  
Vol 283 (6) ◽  
pp. L1192-L1199 ◽  
Author(s):  
Philip W. Shaul ◽  
Sam Afshar ◽  
Linda L. Gibson ◽  
Todd S. Sherman ◽  
Jay D. Kerecman ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Critical Role ◽  
Perinatal Period ◽  
Postnatal Period ◽  
Developmental Changes ◽  
No Production ◽  
Third Trimester ◽  
Isoform Expression ◽  
Oxide Synthase ◽  
Nos Isoforms

Nitric oxide (NO), produced by NO synthase (NOS), plays a critical role in multiple processes in the lung during the perinatal period. To better understand the regulation of pulmonary NO production in the developing primate, we determined the cell specificity and developmental changes in NOS isoform expression and action in the lungs of third-trimester fetal baboons. Immunohistochemistry in lungs obtained at 175 days (d) of gestation (term = 185 d) revealed that all three NOS isoforms, neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS), are primarily expressed in proximal airway epithelium. In proximal lung, there was a marked increase in total NOS enzymatic activity from 125 to 140 d gestation due to elevations in nNOS and eNOS, whereas iNOS expression and activity were minimal. Total NOS activity was constant from 140 to 175 d gestation, and during the latter stage (160–175 d gestation), a dramatic fall in nNOS and eNOS was replaced by a rise in iNOS. Studies done within 1 h of delivery at 125 or 140 d gestation revealed that the principal increase in NOS during the third trimester is associated with an elevation in exhaled NO levels, a decline in expiratory resistance, and greater pulmonary compliance. Thus, there are developmental increases in pulmonary NOS expression and NO production during the early third trimester in the primate that may enhance airway and parenchymal function in the immediate postnatal period.

Persistent Pulmonary Hypertension of the Newborn: Role of Nitric Oxide

1995 ◽  
Vol 10 (6) ◽  
pp. 270-282
Author(s):  
Stella Kourembanas
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Structural Changes ◽  
Critical Role ◽  
Persistent Pulmonary Hypertension ◽  
Cell Contractility ◽  
Vasoactive Mediators ◽  
Nitric Oxide Therapy

Persistent pulmonary hypertension of the newborn (PPHN) is a common cause of respiratory failure in the full-term neonate. Molecular and cellular studies in vascular biology have revealed that endothelial-derived mediators play a critical role in the pathogenesis and treatment of PPHN. Endothelial-derived vasoconstrictors, like endothelin, may increase smooth muscle cell contractility and growth, leading to the physiologic and structural changes observed in the pulmonary arterioles of infants with this disease. On the other hand, decreased production of the endothelial-derived relaxing factor, nitric oxide, may exacerbate pulmonary vasoreactivity and lead to more severe pulmonary hypertension. Exogenous (inhaled) nitric oxide therapy reduces pulmonary vascular resistance and improves oxygenation. The safety and efficacy of this therapy in reducing the need for extracorporeal membrane oxygenation and decreasing long-term morbidity is being tested in several trials nationally and abroad. Understanding the basic mechanisms that regulate the gene expression and production of these vasoactive mediators will lead to improved preventive and therapeutic strategies for PPHN.

Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm NOx Burner With Periodic Flue Gas Recirculation

2004 ◽  
Author(s):  
Jochen R. Kalb ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Gas Content ◽  
Stable Operation ◽  
Reacting Flow ◽  
Nox Emissions ◽  
Lean Blowout ◽  
Fresh Mixture ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

The technological objective of this work is the development of a lean-premixed burner for natural gas. Sub-ppm NOx emissions can be accomplished by shifting the lean blowout limit (LBO) to slightly lower adiabatic flame temperatures than the LBO of current standard burners. This can be achieved with a novel burner concept utilizing periodic flue gas recirculation: Hot flue gas is admixed to the injected premixed fresh mixture with a mass flow rate of comparable magnitude, in order to achieve self-ignition. The subsequent combustion of the diluted mixture again delivers flue gas. A fraction of the combustion products is then admixed to the next stream of fresh mixture. This process pattern is to be continued in a cyclically closed topology, in order to achieve stable combustion of e.g. natural gas in a temperature regime of very low NOx production. The principal ignition behavior and NOx production characteristics of one sequence of the periodic process was modeled by an idealized adiabatic system with instantaneous admixture of partially or completely burnt flue gas to one stream of fresh reactants. With the CHEMKIN-II package a reactor network consisting of one perfectly stirred reactor (PSR, providing ignition in the first place) and two plug flow reactors (PFR) has been used. The effect of varying burnout and the influence of the fraction of admixed flue gas have been evaluated. The simulations have been conducted with the reaction mechanism of Miller and Bowman and the GRI-Mech 3.0 mechanism. The results show that the high radical content of partially combusted products leads to a massive decrease of the time required for the formation of the radical pool. As a consequence, self-ignition times of 1 ms are achieved even at adiabatic flame temperatures of 1600 K and less, if the flue gas content is about 50%–60% of the reacting flow after mixing is complete. Interestingly, the effect of radicals on ignition is strong, outweighs the temperature deficiency and thus allows stable operation at very low NOx emissions.

scholarly journals Inhibition of Vascular Nitric Oxide after Rat Chronic Brain Hypoperfusion: Spatial Memory and Immunocytochemical Changes

2005 ◽  
Vol 25 (6) ◽  
pp. 663-672 ◽  
Author(s):  
Jack C. de la Torre ◽  
Gjumrakch Aliev
Keyword(s):  
Nitric Oxide ◽  
Spatial Memory ◽  
Memory Function ◽  
Critical Role ◽  
Artery Occlusion ◽  
Carotid Artery Occlusion ◽  
Significant Loss ◽  
Electron Microscopic ◽  
Vessel Occlusion ◽  
Common Carotid Artery Occlusion

An aging rat model of chronic brain hypoperfusion (CBH) that mimics human mild cognitive impairment (MCI) was used to examine the role of nitric oxide synthase (NOS) isoforms on spatial memory function. Rats with CBH underwent bilateral common carotid artery occlusion (2-vessel occlusion (2-VO)) for either 26 or 8 weeks and were compared with nonoccluded sham controls (S-VO). The neuronal and endothelial (nNOS/eNOS) constitutive inhibitor nitro-L-arginine methyl ester (L-NAME) 20 mg/kg was administered after 26 weeks for 3 days to 2-VO and S-VO groups and spatial memory was assessed with a modified Morris watermaze test. Only 2-VO rats worsened their spatial memory ability after L-NAME. Electron microscopic immunocytochemical examination using an antibody against eNOS showed 2-VO rats had significant loss or absence of eNOS-containing positive gold particles in hippocampal endothelium and these changes were associated with endothelial cell compression, mitochondrial damage and heavy amyloid deposition in hippocampal capillaries and perivascular region. In the 8-week study, three groups of 2-VO rats were administered an acute dose of 7-NI, aminoguanidine or L-NIO, the relatively selective inhibitors of nNOS, inducible NOS and eNOS. Only rats administered the eNOS inhibitor L-NIO worsened markedly their watermaze performance ( P=0.009) when compared with S-VO nonoccluded controls. We conclude from these findings that vascular nitric oxide derived from eNOS may play a critical role in spatial memory function during CBH possibly by keeping cerebral perfusion optimal through its regulation of microvessel tone and cerebral blood flow and that disruption of this mechanism can result in spatial memory impairment. These findings may identify therapeutic targets for preventing MCI and treating Alzheimer's disease.

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