Irritating Atmospheres: Atmospheric Photochemistry

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Internal Combustion Engines ◽  
Radical Reaction ◽  
Ground Level ◽  
Hydrocarbon Fuel ◽  
Electron Cloud ◽  
Oxygen Molecule ◽  
Oh Radicals ◽  
Unburned Hydrocarbon ◽  
Unburned Fuel ◽  
Ultraviolet Photons

The problem of photochemically generated smog begins inside internal combustion engines, where at the high temperatures within the combustion cylinders and the hot exhaust manifold nitrogen molecules and oxygen molecule combine to form nitric oxide, NO. Almost as soon as it is formed, and when the exhaust gases mingle with the atmosphere, some NO is oxidized to the pungent and chemically pugnacious brown gas nitrogen dioxide, NO2, 1. We need to watch what happens when one of these NO2 molecules is exposed to the energetic ultraviolet photons in sunlight. We see a photon strike the molecule and cause a convulsive tremor of its electron cloud. In the brief instant that the electron cloud has swarmed away from one of the bonding regions, an O atom makes its escape, leaving behind an NO molecule. We now continue to watch the liberated O atom. We see it collide with an oxygen molecule, O2, and stick to it to form ozone, O3, 2. This ozone is formed near ground level and is an irritant; ozone at stratospheric levels is a benign ultraviolet shield. Now keep your eye on the ozone molecule. In one instance we see it collide with an NO molecule, which plucks off one of ozone’s O atoms, forming NO2 and letting O3 revert to O2. Another fate awaiting NO2 is for it to react with oxygen and any unburned hydrocarbon fuel and its fragments that have escaped into the atmosphere. We can watch that happening too where the air includes surviving fragments of hydrocarbon fuel molecules. A lot of little steps are involved, and they occur at a wide range of rates. Let’s suppose that some unburned fuel escapes as ethane molecules, CH3CH3, 3. Although ethane is not present in gasoline, a CH3CH2· radical (Reaction 12) would have been formed in its combustion and then combined with an H atom in the tumult of reactions going on there. You already know that vicious little O atoms are lurking in the sunlit NO2-ridden air. We catch sight of one of their venomous acts: in a collision with an H2O molecule they extract an H atom, so forming two ·OH radicals.

Effect of Ring Dynamics and Crevice Flows on Unburned Hydrocarbon Emissions

1994 ◽  
Vol 116 (4) ◽  
pp. 784-792 ◽  
Author(s):  
L. K. Shih ◽  
D. N. Assanis
Keyword(s):  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Design Parameters ◽  
Fuel Vapor ◽  
Hydrocarbon Emissions ◽  
Reacting Flow ◽  
Piston Cylinder ◽  
Unburned Hydrocarbon ◽  
Ring Assembly ◽  
Unburned Fuel

A significant source of unburned hydrocarbon emissions from internal combustion engines originates from the flow of unburned fuel/air mixture into and out of crevices in the piston-cylinder-ring assembly. During compression, fuel vapor flows into crevice regions. After top dead center, the trapped fuel vapor that returns into the cylinder escapes complete oxidation and contributes to unburned hydrocarbon emissions. In this work, the crevice flow model developed by Namazian and Heywood is implemented into KIVA-II, a multidimensional, reacting flow code. Two-dimensional, axisymmetric simulations are then performed for a 2.5 liter gasoline engine to investigate the effects of engine speed and selected piston-ring design parameters on crevice flows and on unburned hydrocarbon emissions. Results suggest that engine-out unburned hydrocarbon emissions can be reduced by optimizing the ring end gap area and the piston-cylinder side clearance.

scholarly journals Hydrogen application in internal combustion engines

2020 ◽  
Vol 21 (1) ◽  
pp. 14-19
Author(s):  
Arthur R. Asoyan ◽  
Igor K. Danilov ◽  
Igor A. Asoyan ◽  
Georgy M. Polishchuk
Keyword(s):  
Burning Rate ◽  
Internal Combustion Engines ◽  
Combustion Process ◽  
Hydrocarbon Fuel ◽  
Internal Combustion ◽  
Technical Solution ◽  
Combustion Engines ◽  
Environmental Friendliness ◽  
Petroleum Origin ◽  
Order Of Magnitude

A technical solution has been proposed to reduce the consumption of basic hydrocarbon fuel, to improve the technical, economic and environmental performance of internal combustion engines by affecting the combustion process of the fuel-air mixture with a minimum effective mass fraction of hydrogen additive in the fuel-air mixture. The burning rate of hydrogen-air mixtures is an order of magnitude greater than the burning rate of similar mixtures based on gasoline or diesel fuel, compared with the former, they are favorably distinguished by their greater detonation stability. With minimal additions of hydrogen to the fuel-air charge, its combustion time is significantly reduced, since hydrogen, having previously mixed with a portion of the air entering the cylinder and burning itself, effectively ignites the mixture in its entirety. Issues related to the accumulation of hydrogen on board the car, its storage, explosion safety, etc., significantly inhibit the development of mass production of cars using hydrogen fuel. The described technical solution allows the generation of hydrogen on board the car and without accumulation to use it as an additive to the main fuel in internal combustion engines. The technical result is to reduce the consumption of hydrocarbon fuels (of petroleum origin) and increase the environmental friendliness of the car due to the reduction of the emission of harmful substances in exhaust gases.

Reaction kinetics of OH radicals with glutaric acid and adipic acid in the aqueous phase

2021 ◽  
Author(s):  
Liang Wen ◽  
Thomas Schaefer ◽  
Hartmut Herrmann
Keyword(s):  
Aqueous Phase ◽  
Adipic Acid ◽  
Rate Constants ◽  
Density Functional ◽  
Glutaric Acid ◽  
Radical Reaction ◽  
Basis Set ◽  
Oh Radicals ◽  
Oh Radical ◽  
Energy Barriers

<p>Dicarboxylic acids (DCAs) are widely distributed in atmospheric aerosols and cloud droplets and are mainly formed by the oxidation of volatile organic compounds (VOCs). For example, glutaric acid and adipic acid are two kinds of the DCAs that can be oxidized by hydroxyl radical (‧OH) reactions in the aqueous phase of aerosols and droplets. In the present study, the temperature- and pH-dependent rate constants of the aqueous OH radical reactions of the two DCAs were investigated by a laser flash photolysis-long path absorption setup using the competition kinetics method. Based on speciation calculations, the OH radical reaction rate constants of the fully protonated (H<sub>2</sub>A), deprotonated (HA<sup>-</sup>) and fully deprotonated (A<sup>2-</sup>) forms of the two DCAs were determined. The following Arrhenius expressions for the T-dependency of the OH radical reaction of glutaric acid, k(T, H<sub>2</sub>A) = (3.9 ± 0.1) × 10<sup>10</sup> × exp[(-1270 ± 200 K)/T], k(T, HA<sup>-</sup>) = (2.3 ± 0.1) × 10<sup>11</sup> × exp[(-1660 ± 190 K)/T], k(T, A<sup>2-</sup>) = (1.4 ± 0.1) × 10<sup>11</sup> × exp[(-1400 ± 170 K)/T] and adipic acid, k(T, H<sub>2</sub>A) = (7.5 ± 0.2) × 10<sup>10</sup> × exp[(-1210 ± 170 K)/T], k(T, HA<sup>-</sup>) = (9.5 ± 0.3) × 10<sup>10</sup> × exp[(-1200 ± 200 K)/T], k(T, A<sup>2-</sup>) = (8.7 ± 0.2) × 10<sup>10</sup> × exp[(-1100 ± 170 K)/T] (in unit of L mol<sup>-1</sup> s<sup>-1</sup>) were derived.</p><p>The energy barriers of the H-atom abstractions were simulated by the Density Functional Theory calculations run with the GAUSSIAN package using the M06-2X method and the basis set m062x/6-311++g(3df,2p). The results showed that the energy barriers were lower at the C<sub>β</sub>-atoms and are higher at the C<sub>α</sub>-atoms of the two DCAs, clearly suggesting that the H-atom abstractions occurred predominately at the C<sub>β</sub>-atoms. In addition, the ionizations can enhance the electrostatic effects of the carboxyl groups, significantly reducing the energy barriers, leading to the order of OH radical reactivity as  <  < . This study intends to better characterize the losing processes of glutaric acid and adipic acid in atmospheres.</p>

Liner Design to Reduce Unburned Hydrocarbon Exhaust Emissions

2018 ◽  
Author(s):  
Paul S. Wang ◽  
Allen Y. Chen
Keyword(s):  
Natural Gas ◽  
Ventilation System ◽  
Hydrocarbon Emissions ◽  
Tracer Technique ◽  
Oil Consumption ◽  
Natural Gas Engines ◽  
Unburned Hydrocarbon ◽  
Crankcase Ventilation ◽  
Unburned Fuel ◽  
Careful Design

Large natural gas engines that introduce premixed fuel and air into the engine cylinders allow a small fraction of fuel to evade combustion, which is undesirable. The premixed fuel and air combust via flame propagation. Ahead of the flame front, the unburned fuel and air are driven into crevices, where conditions are not favorable for oxidation. The unburned fuel is a form of waste and a source of potent greenhouse gas emissions. A concept to vent unburned fuel into the crankcase through built-in slots in the liner during the expansion stroke has been tested. This venting process occurs before the exhaust valve opens and the unburned fuel sent into the crankcase can be recycled to the intake side through a closed crankcase ventilation system. The increased communication between the cylinder and the crankcase changes the ring pack dynamics, which results in higher oil consumption. Oil consumption was measured using a sulfur tracer technique. Careful design is required to achieve the best tradeoff between reductions in unburned hydrocarbon emissions and oil control.

Solute Radical Inactivation of the Sulfhydryl Enzyme Papain – Sensitization and Protection

1973 ◽  
Vol 51 (15) ◽  
pp. 2443-2447 ◽  
Author(s):  
G. M. Gaucher ◽  
Barbara L. Mainman ◽  
D. A. Armstrong
Keyword(s):  
Active Site ◽  
Radical Reaction ◽  
Radical Scavenging ◽  
Oh Radicals ◽  
Molar Ratios ◽  
Γ Rays

Particularly pure N2O-purged papain solutions (2 × 10−5 M; pH 6.8) were irradiated at 0 °C for different times with 60Co γ-rays, in the presence of 10−30 mM solutions of acetate, isobutanol, and thiocyanate. In comparison to OH radicals, these solute radicals substantially enhanced papain inactivation. Calculated inactivation probabilities per papain–radical reaction (i.e. 0.43 for OH and 1.00 for solute radicals) support this finding.In situ protection of both N2-purged and N2O saturated papain solutions by cysteine was found to occur only at cysteine: papain molar ratios above 15:1, while below this ratio substantial sensitization occurred, reaching a maximum at a 2:1 ratio. This enhanced inactivation of papain at low cysteine concentrations is primarily repairable in nature, and probably due to CysS• attack on papain's active site sulfhydryl. Only at relatively high cysteine:papain ratios (> 30) can protection be ascribed simply to radical scavenging.

scholarly journals Importance of SOA formation of α-pinene, limonene and <i>m</i>-cresol comparing day-and night-time radical chemistry

2020 ◽  
Author(s):  
Anke Mutzel ◽  
Yanli Zhang ◽  
Olaf Böge ◽  
Maria Rodigast ◽  
Agata Kolodziejczyk ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Radical Reaction ◽  
Water Soluble ◽  
Oh Radicals ◽  
Oh Radical ◽  
Night Time ◽  
Formation Potential ◽  
Phase Constituent ◽  
Dry Conditions ◽  
The One

Abstract. The oxidation of biogenic and anthropogenic compounds leads to the formation of secondary organic aerosol mass (SOA). The present study aims to investigate α-pinene, limonene and m-cresol with regards to their SOA formation potential dependent on relative humidity (RH) under night- (NO3 radicals) and day-time conditions (OH radicals) and the resulting chemical composition. It was found that SOA formation potential of limonene with NO3 significantly exceeds the one of the OH radical reaction, with SOA yields of 15–30 % and 10–21 %, respectively. Additionally, the nocturnal SOA yield was found to be very sensitive towards RH, yielding more SOA under dry conditions. On the contrary, the SOA formation potential of α-pinene with NO3 slightly exceeds that of the OH radical reaction, independent from RH. In average, α-pinene yielded SOA with about 6–7 % from NO3 radicals and 3–4 % from OH radical reaction. Surprisingly, unexpected high SOA yields were found for m-cresol oxidation with OH radicals (3–9 %) with the highest yield under elevated RH (9 %) which is most likely attributed to a higher fraction of 3-methyl-6-nitro-catechol (MNC). While α-pinene and m-cresol SOA was found to be mainly composed of water-soluble compounds, 50–68 % of nocturnal SOA and 22–39 % of daytime limonene SOA is water-insoluble. The fraction of SOA-bound peroxides which originated from α-pinene varied between 2–80 % as a function of RH. Furthermore, SOA from α-pinene revealed pinonic acid as the most important particle-phase constituent under day- and night-time conditions with fraction of 1–4 %. Further compounds detected are norpinonic acid (0.05–1.1 % mass fraction), terpenylic acid (0.1–1.1 % mass fraction), pinic acid (0.1–1.8 % mass fraction) and 3-methyl-1,2,3-tricarboxylic acid (0.05–0.5 % mass fraction). All marker compounds showed higher fractions under dry conditions when formed during daytime and almost no RH effect when formed during night.

Trapped Unburned Fuel Estimation and Robustness Analysis for a Turbocharged Diesel Engine With Negative Valve Overlap Strategy

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Song Chen ◽  
Fengjun Yan
Keyword(s):  
Theoretical Analysis ◽  
Internal Combustion Engines ◽  
Combustion Process ◽  
Robustness Analysis ◽  
Linear Matrix ◽  
Fuel Mass ◽  
Residual Gas ◽  
Unburned Fuel ◽  
Negative Valve Overlap ◽  
Valve Overlap

Turbocharger and negative valve overlap (NVO) strategy are widely used among advanced combustion modes for internal combustion engines. In order to achieve well emission performance, the NVO can be as large as 100 crank angle (CA) degrees, such that the residual gas fraction can be up to 40%. With such amount of residual gas in the cylinder, the trapped unburned fuel is not trivial. It has a significant impact on the combustion process. However, the trapped unburned fuel mass is hard to be measured directly. In this paper, a novel method based on the signals of oxygen fraction is proposed to estimate it. By analyzing the combustion process, dynamic equations for the intake/exhaust manifolds and in-cylinder oxygen fractions, as well as actual fuel mass in the cylinder are constructed. A smooth variable structure filter (SVSF) was designed to estimate oxygen fractions and further the trapped unburned fuel. As a comparison, Kalman filter (KF) and linear matrix inequality (LMI) based linear parameter-varying (LPV) filter were also applied. Robustness properties of the three observers are analyzed based on the theory of input-to-state (ISS) stability. The proposed models and methods and theoretical analysis are validated and compared through a set of simulations in high-fidelity GT-Power environment. The simulation results match well with theoretical analysis that the SVSF has good properties of strong robustness (with a root mean square error (RMSE) of 0.24, comparing with 0.4 of LPV filter and 0.49 of KF, for the unburned fuel estimation).

scholarly journals HOW TO MAKE KAZAKHSTAN THE MOST COMPETITIVE AND TECHNOLOGICALLY INNOVATIVE COUNTRY OF THE WORLD

Neft i gaz ◽  
2020 ◽  
Vol 3-4 (117-1118) ◽  
pp. 7-50
Author(s):  
N.K. NADIROV ◽  
Keyword(s):  
Renewable Energy ◽  
Internal Combustion Engines ◽  
Oil And Gas ◽  
Oil Production ◽  
Oil And Gas Industry ◽  
Hydrocarbon Fuel ◽  
High Water ◽  
Scientific Publications ◽  
The World ◽  
The Republic

The oil industry, like the world economy as a whole, has been shaken by the previously unseen crisis triggeredbytheCOVID-19pandemic.Urgentmeasuresrequires tochallenge andovercomeit. Believing that only reliance on innovation, technological progress, human capital will ensure the survival of the industry, the article below outlines the essence of fundamentally new, patented or diploma-protected scientific discoveries, technologies that address to resolve the challenges and ensure the Kazakhstan’s economic, environmental and commercial supremacy in every step of oil production – from oil exploration all the way to a gas tank. The National Engineering Academy of the Republic of Kazakhstan has accumulated a large base of such solutions. In the field of exploration: space sciencecomplimenting geologicalinnovative methods, both regional and detailed, allow for an order of magnitude cheaper, more accurately identify promising search sites and discover new oil and gas fields. In the field of oil production and transportation: GALEX technologies will ensure the production of ultra-viscous, hard-to-recover oil, high water cut, depleted fields at a cost of not exceeding 4–5 dollars per barrel; transportation by pipelines of oil volumes times greater than the base volume at no costs increase. Inthefieldofoilrefining:low-temperaturehydro-conversiontechnology,technology foron-site synthesizing petroleum products from crude oil will allow deep processing of hydrocarbon products of any specifications at relatively low temperatures, produce market-demanded products with the possibility of rapid reprofiling of production. In the area of hydrocarbon fuel efficiency and environmental efficiency: to reformat hydrocarbon fuels prior being burned in internal combustion engines with savings of 30% or more, 10 НЕФТЬ И ГАЗ 2020. 3–4 (117–118) АКТУАЛЬНО with a reduction in greenhouse gas emissions by 30% or more, the elimination of poisonous substances emissions into the biosphere by 95–98%, can be used with patented andproven SALF technology and devices. In the field of renewable energy: renewable energy technologies will significantly reduce the energy intensity of the entire industry, provide the population of hard-to-reach and remote areas with cheap energy and fresh water. The references in the text are a database of scientific publications, discoveries, engineering and engineering, protected patents and diplomas, recommendations created by scientists, oil professionals, inventors of the National Academy of Engineering of the Republic of Kazakhstan, which can be submitted for use for purpose in the oil and gas industry

scholarly journals Experimental Testing of Combustion Parameters and Emissions of Waste Motor Oil and Its Diesel Mixtures

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5950
Author(s):  
Dragiša Đorđić ◽  
Milan Milotić ◽  
Zoran Ćurguz ◽  
Slavko Đurić ◽  
Tihomir Đurić
Keyword(s):  
Diesel Fuel ◽  
Alternative Fuels ◽  
Internal Combustion Engines ◽  
Experimental Testing ◽  
Hydrocarbon Fuel ◽  
Engine Oil ◽  
Heat Output ◽  
Gas Temperature ◽  
Waste Engine Oil ◽  
Motor Oils

The production of hydrocarbon fuel from waste engine oil is an excellent way to produce alternative fuels. The aim of the research in this paper is obtaining fuel with a mixture of waste engine oil (WMO) and diesel fuel that can be used as an alternative fuel for internal combustion engines and low power heat generators. With this goal in mind, tests were conducted to estimate the combustion parameters and emissions at a low heat output of 40 kW. Waste motor oils (WMO) and four of its diesel mixtures were used, varying in weight from 20% WMO to 50% WMO. Test results were analysed and compared with diesel fuel. Higher NO, CO and CO2 emissions were determined for WMO and its mixtures compared to diesel fuel. The flue gas temperature in the kiln was high for all WMO and diesel blends, which indicates the efficiency of the input energy. The absorption of flue gases in the scrubber with distilled water showed higher presence of sulphates, sulphides, nitrates and nitrites compared to allowable values.

Real-time monitoring for reforming processes of liquid hydrocarbon fuel–air pre-mixtures by non-thermal plasmas using ion attachment mass spectrometry

2018 ◽  
Vol 20 (2) ◽  
pp. 1082-1090 ◽  
Author(s):  
Daiki Asakawa ◽  
Akira Kuramochi ◽  
Eiichi Takahashi ◽  
Naoaki Saito
Keyword(s):  
Mass Spectrometry ◽  
Low Temperature ◽  
Internal Combustion Engines ◽  
Hydrocarbon Fuel ◽  
Liquid Hydrocarbon ◽  
Combustion Engines ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Ion Attachment ◽  
Combustion Technique

Plasma induced reforming processes of fuel–air mixtures were investigated to understand the mechanism of the low temperature plasma-assisted combustion technique, which can improve the thermal efficiency and stability of internal combustion engines.

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