scholarly journals Gaseous combustion at high pressures. Part XV.— The formation of nitric oxide in carbonic oxide-oxygen-nitrogen explosions

1933 ◽  
Vol 139 (837) ◽  
pp. 74-83 ◽  
Keyword(s):  
Nitric Oxide ◽  
High Pressures ◽  
Volume Ratio ◽  
Optimum Composition ◽  
Normal Rate ◽  
Secondary Formation ◽  
Spherical Explosion ◽  
Rate Of Cooling ◽  
Hot Products

In previous papers of this series it was shown that the secondary formation of nitric oxide in CO-O 2 -N 2 explosions, when oxygen is present in excess of that required to burn all the carbonic oxide, rapidly increases with the density of the medium, the optimum composition of the medium for the purpose being 2CO + 3O 2 + 2N 2 . The former experiments were carried out, in bombs Nos. 2 and 3, the 7·5 cm. diameter spherical explosion chambers of which were each of 240 c.c. capacity with a surface/volume ratio 0·78, under conditions permitting of no acceleration in the normal rate of cooling down of the hot products from the maximum explosion temperature.

Effect of surface on the gas-phase oxidation of methanol catalysed by nitric oxide

1964 ◽  
Vol 17 (5) ◽  
pp. 539
Author(s):  
JJ Batten
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Marked Effect ◽  
Volume Ratio ◽  
Oxidation Of Methanol ◽  
Inorganic Substances ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Kinetics Of ◽  
Effect Of Surface

A study has been made of the effect of the surface-to-volume ratio of the reaction vessel and of coatings of various inorganic substances on the vessel walls on the gas-phase oxidation of methanol catalysed by nitric oxide. The results show that, whereas packing the vessel does not have a marked effect on the rate, the kinetics of the reaction are profoundly influenced by the nature of the surface. The results suggest that the methanol-oxidation chains are initiated at the surface by reaction between methanol and nitrogen dioxide, and that HO2 radicals play an important role in the subsequent chain reaction.

Effect of High Pressures On the Formation of Nitric Oxide in Lean, Premixed Flames

2020 ◽  
Author(s):  
Philippe Versailles ◽  
Antoine Durocher ◽  
Gilles Bourque ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Nitric Oxide ◽  
High Pressures ◽  
Flame Temperature ◽  
Laminar Jet ◽  
Lean Premixed Flames ◽  
Path Analyses ◽  
Lean Premixed ◽  
Premixed Laminar ◽  
Negative Impacts ◽  
Hydrogen Radicals

Abstract Increasingly stringent regulations are imposed on NOx emissions due to their numerous negative impacts on human health and the environment. Experimentally validated thermochemical models are required for the development of the next generation of combustors. This paper presents experiments performed in lean, premixed, laminar, jet-wall stagnation flames at pressures of 2, 4, 8, and 16 atm. To target post-flame temperatures relevant to gas turbine engines, the stoichiometry of the non-preheated methane-air mixture is adjusted to an equivalence ratio of 0.7. One-dimensional profiles of temperature and NO mole fraction are measured via laser-induced fluorescence (LIF) thermometry and NO-LIF, respectively, to complement previously published flame speed data by Versailles et al. As the pressure increases, the maximum post-flame temperature stays relatively stable, and the concentration of NO produced through the flame front remains constant within uncertainty. Seven thermochemical models, selected for their widespread usage or recent date of publication, are validated against the experimental data. While all mechanisms accurately predict the post-flame temperature, important disagreements are observed in the NO concentration profiles, which highlights the need to carefully select the models used as design tools. The lack of pressure dependence of NO formation that many models fail to capture is numerically investigated via sensitivity and reaction path analyses. The termolecular reaction H+O2 (+M)<=>HO2(+M) is shown to hinder the production of atomic oxygen and hydrogen radicals at higher pressures, which inhibits the formation of nitric oxide through the N2O pathway.

THE KINETICS OF THE THERMAL DECOMPOSITIONS OF THE LOWER PARAFFINS: V. THE NITRIC OXIDE INHIBITED DECOMPOSITION OF n-BUTANE

1940 ◽  
Vol 18b (1) ◽  
pp. 1-11 ◽  
Author(s):  
E. W. R. Steacie ◽  
H. O. Folkins
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Free Radical ◽  
High Pressures ◽  
Free Radical Processes ◽  
Temperature Range ◽  
Radical Recombination ◽  
Radical Processes ◽  
Kinetics Of ◽  
Good Agreement

A detailed investigation of the inhibition by nitric oxide of the thermal decomposition of n-butane has been carried out over the temperature range 500° to 550 °C.In all cases it was found that inhibition decreased with increasing butane concentration. This suggests that radical recombination occurs in the normal decomposition by ternary collisions with butane molecules acting as third bodies.The activation energies of the normal and inhibited reactions have been determined. For high pressures the two values are in good agreement, viz., 58,200 and 57,200 cal. per mole respectively. The products of the inhibited reaction were also found to be the same as those of the normal reaction.It is concluded that free radical processes predominate, involving comparatively short chains.

Effect of Hyperbaric Oxygen Treatment on Nitric Oxide and Oxygen Free Radicals in Rat Brain

2000 ◽  
Vol 83 (4) ◽  
pp. 2022-2029 ◽  
Author(s):  
Ikram M. Elayan ◽  
Milton J. Axley ◽  
Paruchuri V. Prasad ◽  
Stephen T. Ahlers ◽  
Charles R. Auker
Keyword(s):  
Nitric Oxide ◽  
Free Radicals ◽  
Rat Brain ◽  
Hyperbaric Oxygen ◽  
High Pressures ◽  
Oxygen Free Radicals ◽  
In Vivo Microdialysis ◽  
Sprague Dawley ◽  
Fourfold Increase

Oxygen (O2) at high pressures acts as a neurotoxic agent leading to convulsions. The mechanism of this neurotoxicity is not known; however, oxygen free radicals and nitric oxide (NO) have been suggested as contributors. This study was designed to follow the formation of oxygen free radicals and NO in the rat brain under hyperbaric oxygen (HBO) conditions using in vivo microdialysis. Male Sprague-Dawley rats were exposed to 100% O2 at a pressure of 3 atm absolute for 2 h. The formation of 2,3-dihydroxybenzoic acid (2,3-DHBA) as a result of perfusing sodium salicylate was followed as an indicator for the formation of hydroxyl radicals. 2,3-DHBA levels in hippocampal and striatal dialysates of animals exposed to HBO conditions were not significantly different from controls. However, rats treated under the same conditions showed a six- and fourfold increase in nitrite/nitrate, break down products of NO decomposition, in hippocampal and striatal dialysates, respectively. This increase was completely blocked by the nitric oxide synthase (NOS) inhibitor l-nitroarginine methyl ester (l-NAME). Using neuronal NOS, we determined the NOS O2 K m to be 158 ± 28 (SD) mmHg, a value which suggests that production of NO by NOS would increase approximately four- to fivefold under hyperbaric O2 conditions, closely matching the measured increase in vivo. The increase in NO levels may be partially responsible for some of the detrimental effects of HBO conditions.

Fluorescence and vibrational relaxation of nitric oxide studied by kinetic spectroscopy

1961 ◽  
Vol 260 (1303) ◽  
pp. 459-474 ◽  
Keyword(s):  
Nitric Oxide ◽  
Vibrational Relaxation ◽  
High Pressures ◽  
Flash Photolysis ◽  
Electronic States ◽  
Analytic Form ◽  
Gas Mixtures ◽  
Inert Gas ◽  
Flash Duration ◽  
Kinetic Spectroscopy

The first excited vibrational level of the ground electronic states of nitric oxide was popu­lated above its equilibrium value by flash photolysis of nitric oxide + inert gas mixtures, under isothermal conditions. Electronic excitation NO 2 II ( v = 0) + hv → NO 2 Ʃ ( v = 0, 1, 2) was followed either by fluorescence NO 2 Ʃ ( v = 0, 1, 2) → NO 2 II ( v = 0, 1, 2...) + hv , or by quenching NO 2 Ʃ ( v = 0, 1, 2) + M → NO 2 II( v = 0, 1, 2...) + M , causing a non-equilibrium population of the vibrational levels of the ground electronic states. Subsequently, the reactions NO 2 II ( v = 1) + M → NO 2 II ( v = 0) + M and NO 2 II ( v = 1) + NO 2 II ( v = 0) → 2NO 2 II ( v = 1) caused a decay of the vibrationally excited molecules with time; this was followed in absorption by kinetic spectroscopy. Because of the rapidity of the last reaction, bands of NO2 II with v >1 were usually observed only in the fluorescence spectrum. In mixtures of 1 to 5 mm of NO with a large excess of nitrogen or krypton, the con­centration of NO2 II ( v = 1) produced by the flash was of the order of 10-1 mm pressure, i. e. about the same concentration which is present in one atmosphere pressure of NO at room temperature. The absolute concentration of NO2 II ( v = 1) was measured accurately by plate photometry, high pressures of NO being used for calibration. The recorded probabilities of vibrational relaxation, P1-0, for NO2 II ( v = 1), and radii for electronic quenching, σ e , by NO, N 2 , CO, H 2 O and CO 2 , are P 1-0 σ e (Å) NO 3.55 x 10 -4 14 N 2 4 x 10 -7 ≤ 2x 10 -2 CO 2.5 x 10 -5 0.6 H 2 O 7 x 10 -3 30 CO 2 1.7 x 10 -4 5 With the use of an analytic form for the flash duration, the entire rise and fall of the concentration of excited species was quantitatively interpreted. A very small fraction of the NO was decomposed by the flash, due either to absorption of radiation below 1900 Å or by reaction of metastable NO molecules with each other or with ground state molecules. Abnormal effects were observed in NO+ H 2 +inert gas mixtures and chemical reaction occurred.

Regional transcapillary albumin exchange in rodent endotoxaemia: effects of fluid resuscitation and inhibition of nitric oxide synthase

2000 ◽  
Vol 100 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Suveer SINGH ◽  
Peter B. ANNING ◽  
C. Peter WINLOVE ◽  
Timothy W. EVANS
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Surface Area ◽  
Blood Volume ◽  
Fluid Resuscitation ◽  
Volume Ratio ◽  
Capillary Density ◽  
Microvascular Permeability ◽  
Capillary Perfusion ◽  
Dual Isotope

Sepsis is characterized by increased microvascular permeability and regional variations in capillary perfusion, which may be modulated by nitric oxide (NO) and reversed by fluid resuscitation (FR). The effects of saline FR and NO synthase blockade [by NG-nitro-L-arginine methyl ester (L-NAME)] on microvascular albumin transport and perfused capillary density were assessed in anaesthetized Wistar rats with acute normodynamic endotoxaemia. Separate dual-isotope techniques were employed to measure the permeability index (PIA) and the permeability×surface area product index (PIB), which provide different and complementary information regarding blood–tissue albumin exchange. PIA represents the tissue/blood distribution volume ratio of albumin. PIB is a composite measure of endothelial permeability and the vascular surface area available for albumin exchange, and therefore takes into account the effect of altered blood volume. Capillary density was quantified by fluorescence microscopy following circulation of Evans Blue-labelled albumin. Compared with controls, PIA was reduced significantly in lipopolysaccharide (LPS)-treated animals in skeletal muscle and skin, probably due to blood volume redistribution rather than to changes in permeability. PIB was increased significantly in LPS-treated animals in the kidney, mesentery, skeletal muscle, skin and lung, and in the small bowel following FR. FR also improved the LPS-induced metabolic base deficit, but did not alter capillary density. L-NAME significantly attenuated the LPS-induced rise in PIB in the lung. In conclusion, acute endotoxaemia induces tissue-dependent variations in microvascular albumin exchange. FR improves acid–base disturbance in endotoxaemia, through mechanisms other than microvascular recruitment. NO appears to increase microvascular permeability in endotoxaemia, an effect that may be attenuated by L-NAME, particularly in the lung.

scholarly journals Gaseous combustion at high pressures, Part XIV. Explosions of hydrogen-air and carbonic oxide-air mixtures at initial pressures up to 1000 atmospheres

1933 ◽  
Vol 139 (837) ◽  
pp. 57-74 ◽  
Keyword(s):  
Nitric Oxide ◽  
High Pressures ◽  
Maximum Pressure ◽  
Exothermic Effect ◽  
Complete Combustion ◽  
Cooling Period ◽  
Points Of Interest ◽  
The Subject ◽  
The Many ◽  
Cumulative Evidence

In the previous papers of this series have been described explosions of theoretical hydrogen-air, carbonic oxide-air, etc., mixtures in spherical steel enclosures at initial pressures up to 175 atmospheres; and in 1929 our collected researches on the subject were published in a separate volume entitled “Gaseous Combustion at High Pressures,” in which their theoretical implications were fully considered in the light of the experimental evidence as a whole. Without recapitulating all the many points of interest established during the work, there was one of outstanding importance which should now be recalled, namely, the discovery, attested by an overwhelming mass of cumulative evidence, which is set forth in Chapters IX to XIII (pp. 120 to 208) of our book, of N 2 -activation in CO -O 2 -N 2 explosions at high initial pressures due to an absorption by N 2 -molecules of the radiation emitted by the burning carbonic oxide. In theoretical CO-air explosions this was marked by (i) a continuously increasing “lag” in the time taken for the attainment of maximum pressure, as the density of the medium was increased from P i - = 10 to P i - = 175 atmospheres, and (ii) a strong exothermic effect during the subsequent “cooling period ” ( without there having been any corresponding suppression of Kinetic energy during the explosion itself ), as the activated N 2 molecules slowly reverted to their normal condition. Moreover in explosions of CO-O 2 -N 2 mixtures containing oxygen in excess of that required for the complete combustion of the carbonic oxide, the so-activated nitrogen reacted with the excess of oxygen with the production of large quantities of nitric oxide.

scholarly journals The pressure of explosions.—Experiments on solid and gaseous explosives

1905 ◽  
Vol 76 (513) ◽  
pp. 492-494 ◽  
Keyword(s):  
High Pressures ◽  
Maximum Pressure ◽  
Gaseous Mixtures ◽  
Coal Gas ◽  
Gaseous Products ◽  
Solid Explosives ◽  
Rate Of Cooling

Although this subject has been dealt with by numerous investigators, certain branches of it still remain practically untouched. With regard to the solid explosives used in ballistic work, the maximum pressure developed is usually well known, but the conditions which govern the combustion of the charge and the rate of cooling of the gaseous products require further investigation. Explosive gaseous mixtures have only been studied at initial pressures but little above that of the atmosphere. Even in the case of coal-gas and air, which forms an exception to this rule, the work has not been extended to high pressures. The present research was undertaken with a view to filling in these gaps.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons II. Comparative measurements on the series from propane to n -decane

1950 ◽  
Vol 201 (1064) ◽  
pp. 18-26 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
High Pressures ◽  
Single Mode ◽  
Second Order ◽  
Chain Reaction ◽  
Molecular Rearrangement ◽  
Normal Paraffin ◽  
Rearrangement Process ◽  
Kinetics Of

The rates of the nitric oxide-inhibited decompositions of hydrocarbons in the series propane to n -decane (which according to the results of Part I represent the chain-free molecular reactions) have been measured over a range of pressures. As inferred from the 'apparent chain length' the molecular rearrangement process increases in importance relatively to the chain reaction with the ascent of the series, and, for a given hydrocarbon, with increasing pressure. For each hydrocarbon, the order of reaction varies between the first and the second. The results are not consistent with a constant order of 1.5 as has been suggested. Nor is the pressure dependence consistent with the uniform transition from second order to first predicted for unimolecular reactions dependent upon a single mode of activation by collision. There appears to be a contribution to the overall reaction from processes which remain of second order up to high pressures. The decomposition rate for a given hydrocarbon pressure tends to a limit as the series is ascended, for reasons which are discussed.

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