Nitrogen Oxides NOx Research Articles

Аналіз екологічної ефективності димових труб котелень за умов застосування теплоутилізаційних технологій

Виконано аналіз екологічної ефективності димових труб газоспоживальних котелень комунальної теплоенергетики за умов застосування сучасних теплоутилізаційних технологій з охолодженням відхідних димових газів нижче від температури роси водяної пари, що міститься в газах. У цих технологіях використовували теплоутилізатори, призначені для нагрівання зворотної тепломережної води котельні, та тепловий метод антикорозійного захисту газовідвідних трактів шляхом байпасування частини гарячих газів від котла повз зазначене теплоутилізаційне устаткування. Розглянуто одиночні димові труби різного типу під час виготовлення корпусу труби з антикорозійного матеріалу або під час монтування в цегляну (або іншу трубу з покращеними теплоізоляційними властивостями) газовідвідних стволів з цих матеріалів. Доліджено показники максимальних приземних концентрацій у навколишньому середовищі труби найшкідливіших викидів димових газів, таких як окиси вуглецю СО і азоту NOх залежно від режиму роботи котлів згідно з тепломережним графіком роботи котельні. Проаналізовано вплив використання теплоутилізаційних технологій та зазначеного теплового методу захисту димових труб на безпеку експлуатації газовідвідних трактів і на умови розсіювання шкідливих викидів. Показано, що в разі дотримання рекомендованих режимів роботи котлів зі зменшенням їх кількості згідно з тепломережним графіком роботи котельні й в разі застосування сучасних теплоутилізаційних технологій та димових труб з антикорозійних матеріалів реалізується розсіювання викидів СО та NOх у навколишньому середовищі згідно зі сучасними нормативними вимогами.

Recycling and utilisation of faba bean harvesting and threshing waste for bioenergy

This article analyses and evaluates the impact of the technology of soil processing on the biomass indicators of faba bean waste. Samples from five different primary tillage systems were taken and analysed. The raw material of faba bean waste was processed and pressed into cylindrical pellets. The results of the experimental research of the pellet properties revealed that the content of moisture of the pellets from faba bean waste changed from 8.2% (deep cultivation, 3-GP) to 10.8% (untreated soil, 5-ND). The highest density of faba bean waste pellets was obtained from the sample of conventional soil ploughing, (1-IA) (1311 kg m−3), while the lowest density was recorded under shallow ploughing (2-SA) – 1275 kg m−3. The lower calorific value of dry biofuel from faba bean waste pellets was similar in all the samples and ranged from 16.9 MJ kg−1 (5-ND) to 17.1 MJ kg−1 (2-SP). The calorific value of faba bean waste pellets was relatively high and was close to the calorific value of some types of wood waste. The following harmful gas emissions were analysed and evaluated: carbon monoxide CO, carbon dioxide CO2, unburned hydrocarbons CxHy, and nitrogen oxides NOx. The harmful gas environmental emissions detected while burning the pellets of faba bean waste have not exceeded the permissible limits. The best results of the pellet properties, the content of ash and the emissions were obtained under conventional ploughing (1-IA) and deep cultivation (3-GP). The research results suggest that faba bean waste could be used as granulated biofuel, since the main parameters of this legume waste correspond to the basic requirements of solid biofuel. It was determined that under untreated soil (5-ND) technology the CO2 emissions eqv. were twice lower than under conventional soil ploughing (1-IA). These results show that no-till technology is suitable for sustainable agricultural practise both for producing the faba bean grain and for processing the pellets from the waste.

The Environmental Safety of the Fiat 0.9 TwinAir Compressed Natural Gas Engine

The article presents the results of measurements of concentrations of selected exhaust components of the Fiat 0.9 TwinAir spark-ignition engine operating according to load characteristics. The tested engine has an indirect, multi-point petrol supply system and has been retrofitted with an indirect CNG injection system. The results of the tests are a comparison of selected economic, ecological and energetic indicators of engine operation obtained when fuelled with CNG and 95 octane petrol. The operation of the engine fuelled with gaseous fuel was preceded by autocalibration of the controller of the fuelling system. The article presents the results of tests of concentrations of harmful components of exhaust gases: carbon dioxide CO2, carbon monoxide CO, nitrogen oxides NOx and HC hydrocarbons. Moreover, the values of lambda λ air excess coefficient are presented and fuel consumption is compared. The obtained results of the tests of the engine fuelled with CNG gas show a significant decrease in the value of the obtained torque in comparison to the engine torque when fuelled with petrol. The engine fuelled with compressed natural gas contributed to the improvement of its ecological properties and a reduction of fuel consumption, which are important factors of ecological and energy safety. Exhaust gas analysis showed a reduction in the concentration of harmful components of exhaust gases, mainly hydrocarbons and nitrogen oxides. A positive effect of the operation of the engine powered by CNG was also a significant reduction of carbon dioxide in the exhaust gases compared to the engine powered with gasoline.

Experimental investigation of the behaviour of a DI diesel engine fuelled with biodiesel/diesel blends having effect of raw biogas at different operating responses

The ever-growing consumption and rapid exhaustion of fossil fuels along with environmental concern continue to be an important issue for researchers around the world. The quest for improving direct injection (DI) diesel engine performance and reducing emissions has led researchers to explore various aspects of alternate sources of fuels and also have a possibility of dual fuel mode operation. These DI diesel engines use conventional liquid diesel fuel supplemented with gaseous fuels. The present contribution involves, experimental investigation as well as the implementation of response surface methodology (RSM) technique to evaluate the performance of DI diesel engine using biodiesel blends of polanga biodiesel and alcohol along with dual fueling of the engine when gaseous fuel i.e. biogas partially replaces the liquid diesel in the engine. The input parameters considered are types of fuel, speed of the engine, air flow rate and engine load whereas brake thermal efficiency (BTE), volumetric efficiency (VE), and exhaust gas temperature (EGT) along with emission parameters carbon monoxide (CO), (nitrogen oxides) NOx and hydrocarbon (HC) were considered to be the resulting output parameters. The overall good engine performance has been observed at an optimum setting of engine input variables through RSM which is 1495 RPM, 5.8 kg load, 48 mm air flow rate and polanga biodiesel with 10% biogas. The corresponding optimum engine responses of VE, BTE, EGT, NOx, HC, and CO has been observed as 68.92%, 23.62%, 172 oK, 966 ppm volume, 34.65 ppm volume and 0.0876 ppm volume respectively.

Research of the Effectiveness of Selected Methods of Reducing Toxic Exhaust Emissions of Marine Diesel Engines

The article’s applications are very important, as it is only a dozen or so years since the current issues of protection of the atmosphere against emissions of toxic compounds from ships. The issue was discussed against the background of binding legal norms, including rules introduced by the IMO (International Maritime Organization) in the context of the MARPOL Convention (International Convention for the Prevention of Pollution from Ships), Annex VI, with the main goal to significantly strengthen the emission limits in light of technological improvements. Taking these standards into account, effective methods should be implemented to reduce toxic compounds’ emissions to the atmosphere, including nitrogen oxides NOx and carbon dioxide CO2. The purpose of the article was, based on the results of our own research, to indicate the impact of the effectiveness of selected methods on reducing the level of nitrogen oxides and carbon dioxide emitted by the marine engine. The laboratory tests were carried out with the use of the one-cylinder two stroke, crosshead supercharged diesel engine. Methods of reducing their emissions in the study were adopted, including supplying the engine with fuel mixtures of marine diesel oil (MDO) and rapeseed oil ester (RME)-(MDO/RME mixtures) and changing the fuel injection parameters and the advance angles of fuel injection. The supply of the engine during the tests and the mixtures of marine diesel oil (MDO) and rape oil esters (RMEs) caused a clear drop in emissions of nitrogen oxides and carbon dioxide, particularly for a higher engine load, as has been shown. The decrease of the injection advance angle unambiguously makes the NOx content in exhaust gas lower.

Influence of molecular structure of oleoresin-derived compounds on flame properties and emissions from laminar flames.

The search for renewable fuels or components which may improve or replace fossil fuels is an important step towards a sustainable future. In particular, the pine oleoresin produced by conifer trees, which is composed by turpentine oil and non-volatile rosin, may be transformed into alternative fuels. In this work, combustion of six molecules which can be obtained from oleoresin either by distillation (i.e., α- and β-pinene) or by further oxyfunctionalization (nopol, terpineol, myrtenol, and borneol) was studied to assess the potential of pine oleoresin as raw material for biofuels. Emission indices of the main pollutants (carbon monoxide-CO, unburned hydrocarbons-UHC, and nitrogen oxides-NOx) were obtained in non-premixed co-flow laminar flames of the oleoresin-derived molecules blended with n-heptane. The main characteristics of the flames (i.e., temperature and height) were also determined. Significant increase in flame temperature and reduction in CO and UHC emissions with respect to n-heptane were observed with nopol, terpineol, and myrtenol, along an increase in NOx emissions, suggesting an improvement in combustion performance. In addition, differences in emission indices, evidenced for these molecules (even between α- and β-pinene), suggest the importance of the molecular structure in the combustion reaction.

Analysis of some indicators of environmental safety of buses with diesel engines (on the example of Moscow)

The results of studies performed personally by the author and under his leadership on the current level of environmental safety of city buses of Russian-made ecological class Euro-4 (LiAZ-5292-21) and Euro-5 (LiAZ-5256-13 and LiAZ-529-22) according to the smoke level of the exhaust gases provided by GOST R 52160-2003, and not required in actual operation in terms of the content of nitrogen oxides NOX in the exhaust gases of a diesel engine when operating at idle modes. Previous studies on passenger cars and light commercial vehicles with diesel engines (using the operating method developed by us) in accordance with UNECE rules 83.03 (based on urban driving cycles with the results of environmental pollution in g/km) showed an excess of NOX emissions from 7 to 15 times, on the basis of which a simplified technology was developed to control the environmental safety of these vehicles by indicators of the content of CO2 and NOX at idle for a conventional engine with a working m volume of 1 liter. This technique is appropriate to apply for a large vehicle mass, for which NOX emissions at idle is much higher. This will provide operational control of environmental safety by NOX and increased requirements for manufacturers. In a first approximation, the maximum permissible value of the NOX content is justified – no more than 530 ppm. (For comparison, this indicator for cars is significantly lower – no more than 200 ppm). It was additionally established that for estimating CO2 greenhouse gas emissions it is enough (with an error of no more than 10 % to decrease) to use the general indicator of fuel economy – actual fuel consumption: at the same time per 1 kg of diesel fuel, gasoline, liquefied and compressed natural gas, used in operation, 1,500 g of CO2 will be accounted for (conversion to liters is carried out according to the energy density indicators). The studies were carried out as part of comprehensive work to improve the quality of technical servicing of cars, trucks and buses, conducted at the department “Operation of automobile transport and car service” MSARTU (Head of the Department of Doctor of Technical Sciences, Professor A.A. Solntsev).

Variations in the atmospheric pollutant immission (2009\u20132015) field near a large lignite-fired power plant (in Europe/Poland)

Emissions from the energy sector are one of the causes of poor air quality. The status of air pollution caused by the operation of large-size lignite-fired power plants was analyzed (in the years 2009–2015). Emission and immission data from a monitoring station located near a power plant were analyzed (in Europe/Poland in eastern Wielkopolska). The monitoring station conducts continuous measurements of immission concentrations of the following pollutants: PM10, sulfur dioxide (SO2), carbon monoxide (CO), nitrogen oxides NOx (separately and as the sum of NO and NO2), and ozone (O3) recording at the same time with meteorological parameters such as air temperature, relative air humidity, wind speed, and direction. The dependence of concentrations of selected pollutants on temperature at monitoring point was analyzed. The recorded concentrations were compared with values calculated as a result of modeling of pollutants dispersion in the atmosphere.

Review of technologies for suppressing emissions of benzo(a)pyrene at energy enterprises

Power engineering enterprises have a great impact on the environment. Flue gas emissions contain solid ash particles, sulfur oxides SO2, SO3, nitrogen oxides NOx, carbon monoxide CO (monoxide) CH hydrocarbons; in some cases, there may be a danger of radiation contamination, but the most dangerous substance emitted into the atmosphere is benzo(a)pyrene C20H12, which has a negative effect on human health. Polycyclic aromatic hydrocarbons (PAH), including benzo(a)pyrene contained in flue gas emissions from energy enterprises, have a serious impact on human health. Taking measures to suppress other harmful emissions from thermal power plants (nitrogen oxides and sulfur oxides) can increase the content of benzo(a)pyrene, which poses a serious problem for modern researchers. As part of this study, various technologies for suppressing benzo(a)pyrene emissions at energy enterprises were considered. The main disadvantages of the described methods are highlighted. The possible danger of increasing benzo(a)pyrene emissions when trying to suppress other emissions is noted.

Diphenyl diselenide is as effective as Ebselen in a juvenile rat model of cisplatin-induced nephrotoxicity

BackgroundCisplatin (CIS) is widely used in the chemotreatment of pediatric tumors. However, the CIS use is limited because of its high incidence of toxicity, mainly nephrotoxicity. Although there are many studies about CIS-related nephrotoxicity in animal models, only a few studies focus on juvenile animals. Because redox disturbances have been associated with kidney damage induced by CIS, this study aimed to compare the effectiveness of Ebselen and diphenyl diselenide (PhSe)2 against nephrotoxicity induced by CIS in juvenile rats. MethodsJuvenile Wistar rats were randomly divided into six groups: rats from groups I to III received an intraperitoneal (i.p.) injection with saline solution. The other groups received CIS (i.p., 6 mg/kg) on the first day. One hour before CIS injection and on the next four days, animals of groups III and V were intragastrically treated with Ebselen (11 mg/kg) whereas those from groups IV and VI received (PhSe)2 (12 mg/kg). After 24 h of the last treatment, blood and kidney were collected, and the parameters of renal function and oxidative stress were determined. ResultsKidney damage induced by CIS was confirmed by the increase of creatinine, urea and uric acid levels in the blood of juvenile rats. The renal oxidative disturbance was characterized by an increase in the levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl, and nitrogen oxides (Nox), as well as the decrease in non-protein thiol content (NPSH), glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) activities. CIS inhibited the activities of δ-aminolevulinic acid dehydratase (δ-ALA-D) and Na+, K+-ATPase and down-regulated the Nrf2/Keap-1/HO-1 pathway in the kidney of juvenile rats. ConclusionBoth Ebselen and (PhSe)2 modulated back to the normal levels all parameters altered by the CIS administration in the kidney of juvenile rats. Thus, this study shows that (PhSe)2 was as effective as Ebselen in protecting the kidney against oxidative damage caused by CIS in rats.

Study of the diesel engine working process during its operation with a fuel injection pressure of 300 MPa

The paper presents the simulation result of the influence of the ratio of the diameter of the combustion chamber Dкс to its depth hкс and boost pressure рк on the characteristics of a 1ChN 12/13 single-cylinder engine with an injection pressure of 300 MPa at a crankshaft speed of 1400 min-1. The simulation was performed with Dкс/hкс from 3,4 to 10,0, and рк from 0,15 to 0,45 MPa. The results show that the engine achieves the best performance, nitrogen oxides NOx in the exhaust gases decreases at Dкс/hкс = (7,8-10), and the pressure рк from 0,25 to 0,35 MPa. At рк = 0,35 MPa, Dкс/hкс = 10, the indicated power increases by 7,1 %. NOx reduces by 68 % but soot, CO, HC increase 4,5, 9,5, and 2,2 times, respectively. The results also show the impact of the boost pressure on spray characteristics. The boost pressure increases, the penetration, and the tip velocity decrease, but the spray angle changes a little. While the combustion chamber diameter changes, the penetration, and the spray angle change a little, and the tip velocity varies much. Changing the boost pressure is a means of redistributing the amount of fuel burned in the jet and near the wall of the combustion chamber. With an increase in the boost pressure, the proportion of fuel that burns at the beginning of the combustion process under conditions of volumetric mixing increases, while at the end of the combustion process, a large concentration of fuel is located near the combustion chamber wall.

Перспективы применения водородной добавки для двигателей внутреннего сгорания, работающих по циклу Дизеля

The paper presents the results of theoretical and experimental studies of the environmental characteristics of internal combustion engines of commercial and municipal vehicles operating on the Diesel cycle using a hydrogen additive. The analysis of literature sources has confirmed that there are different data regarding harmful emissions when using hydrogen additives for internal combustion engines running on the Diesel cycle. Therewith, data on harmful emissions of nitrogen oxides NOx differ significantly. The results of theoretical and experimental studies of the environmental characteristics of internal combustion engines of commercial and municipal vehicles operating on a Diesel cycle using a hydrogen additive, allow to assert the adequacy of the model, since the error between the theoretical and experimental data did not exceed 14,5 %. It has been found out that the concentration of NOx emissions in an internal combustion engine using a hydrogen additive, working on a Diesel cycle, has decreased by 52 %.The research results confirm the prospects of using a hydrogen additive, which is done for the first time for internal combustion engines running on the Diesel cycle in commercial and municipal vehicles. This guarantees increased environmental safety in urban agglomerations.

Features of application of the methane-hydrogen fraction as fuel for thermal power plant boiler

The methane-hydrogen fraction is a gaseous hydrocarbon by-product during oil processing for obtaining petroleum products. Until recently, the methane-hydrogen fraction was used as furnace oil in internal technological processes at a refinery. Some of the low-calorie methane-hydrogen fraction was burned in flares. Driven by the prospect of the methane-hydrogen fraction use as a fuel alternative to natural gas for burning in thermal power plants boilers, it became necessary to study the methane-hydrogen fraction combustion processes in large volumes. The conversion of ON-1000/1 and ON-1000/2 furnaces from the combustion of the methane- hydrogen fraction with combustion heat of 25.45 MJ/m3 to the combustion of the composition with combustion heat of 18.8 MJ/m3 leads to a decrease in temperature in the flame core for 100 °C as an average. The intensity of flame radiation on the radiant tubes decreases. Therefore, the operation of furnaces during combustion of methane-hydrogen fraction with a low heat of combustion at the gas oil hydro-treating unit is carried out only with a fresh catalyst, which allows lower flame temperatures in the burner.The experiments to determine the concentration of nitrogen oxides NOx and the burning rate w of the methane-hydrogen fraction in the ON-1000/1 furnace and natural gas in the TGM-84A boiler, depending upon the heat of combustion Qnr were carried out. The obtained results showed that the increase in the hydrogen content Н2 from 10.05 % to 18.36% (by mass) results in an increase in the burning rate w by 45%. The burning rate of natural gas with methane CH4 content of 98.89% in the TGM-84A boiler is 0.84 m/s, i.e. it is 2.5 times lower than the burning rate of the methane- hydrogen fraction with H2 content of 10.05%. The distributions of heat flux from the flame qf over the burner height h in the TGM-84A boiler were obtained in case of natural gas burning and calculation of burning of the methane-hydrogen fraction with a hydrogen content of 10.05% and methane of 28.27%. The comparison of the obtained data shows that burning of methane- hydrogen fraction causes an increase in the incident heat flux qf at the outlet of the burner.

NOx scrubbing with H2O2/HNO3 solutions achieved with a laboratory bubble contactor

In this work, the removal of dilute nitrogen oxides NOx from the gaseous effluents of Tunisian nitric acid plant by absorption into aqueous hydrogen peroxide solutions containing or not nitric acid was studied. All semi-continuous absorption tests were carried out at ambient conditions and at 40 Pa as NOx partial pressure. The effects of the gas flow rate, the initial H2O2 concentration and the presence of HNO3 on the NOx absorption efficiency (ANOx) were studied. The tests results revealed that ANOx increases with an increase in initial H2O2 concentration in the scrubbing liquid, but decreases with an increase of gas flow rate. Furthermore, the presence of nitric acid in the aqueous hydrogen peroxide solution has a positive effect on ANOx. These results confirmed that the removal of NOx liberated from the plants of the Tunisian Chemical Group (TCG) by absorption into H2O2 solution is a feasible and an effective solution.

Numerical Investigation on the Effect of Piston Bowl Geometry on Combustion Characteristics of a Heavy-Duty Diesel Engine

Today, due to increased efficiency of heavy-duty diesel engines in the global industry, discussion of the performance of these motors, including higher efficiency and lower emissions, is very important. Several methods exist to meet these demands by the diesel engine. Piston bowl geometry deformation strategy is a reliable method for achieving pollutants of lower nitrogen oxides (Nox) and soot and higher yield. This paper has used Converge software to model the CFD for the performance of a Caterpillar 3401 engine with three different piston bowl geometries and various depths and chamfers for one of the geometries. The compression, inlet temperature, and pressure ratio are assumed to be constant. The results of efficiency and pollution of the engine are presented at all stages for analysis, comparisons, and conclusions. The results show that the cylindrical piston bowl geometry has a proper performance in terms of efficiency and the pollutions produced.

ЗМЕНШЕННЯ ВИКИДІВ СУДНОВОГО ДИЗЕЛЯ УТИЛІЗАЦІЄЮ ТЕПЛОТИ РЕЦИРКУЛЯЦІЙНИХ ГАЗІВ ЕЖЕКТОРНОЮ ХОЛОДИЛЬНОЮ МАШИНОЮ

The problem of air basin pollution of the World Ocean with harmful emissions from the exhaust gases of marine diesel engines is primarily associated with the creation of highly efficient technologies for the neutralization of nitrogen oxides NOx on exhaust gases from a diesel engine. Emissions of harmful substances from the combustion of marine fuels are limited by international atmospheric protection programs and the requirements of the International Maritime Organization (IMO). The requirements relate to almost all groups of harmful emissions in marine engines and the more stringent of them are primarily related to nitrogen oxides NOx and sulfur oxides SOx. To reduce harmful emissions from exhaust gases into the environment, scientists and world engine leaders use and suggest various methods for reducing the content of harmful substances in exhaust gases. The implementation of new standards in the areas of further improvement of the working process, the use of alternative fuels, fuel, and air additives, as well as selective catalytic reduction systems do not preclude further development of scientific research in the field of exhaust gas cleaning. One of the promising ways in environmentalizing marine internal combustion engines is the neutralization of harmful substances in exhaust gases through particular gas recirculation (EGR-technology). However, the use of such techniques conflicts with the engine's energy efficiency. In the work presented, the scheme-design solution of the exhaust gas recirculation system with using the heat of recirculation gases by an ejector refrigeration machine for cooling the air at the intake of ship's main engine is proposed. The effect of using the heat of recirculation gases for cooling the air at the intake of the engine is analyzed taking into account the changing climatic conditions for a particular vessel's route line. It is shown that the use of an ejector refrigeration machine reduces the air temperature at the entrance of the main engine by 5…15 ° С, which reduces the specific fuel consumption. This reduces emissions of harmful substances when the engine is running with recirculation of gases.

On-the-road testing of the effects of driver’s experience, gender, speed, and road grade on car emissions

ABSTRACTOn-road vehicles have become a dominant source of air pollution and energy consumption in many parts of the world. As a result, estimating the amount of pollution from these vehicles and analyzing the factors affecting their emission is necessary to understand and manage ambient air quality. Traditionally, automobile emissions have been measured with dynamometer tests using representative driving cycles. A review of the related literature shows that there is a lack of real life, on-the-road testing of automobile emissions. Moreover, a few previous studies have directly discussed the impact of driver variability on emissions from the vehicles. This research analyzes the impacts of driver experience, gender, speed, and road grade on vehicle emissions through on-the-road testing experiment in Logan, Utah, USA during summer of 2016. The methodology of the research starts by selecting a representative car to perform the tests on. The next step was to choose test drivers representing four groups: young males, young females, experienced males, and experienced females. After that, the drivers were assigned a specified route that has different speed limits and grades. Emissions from the car exhaust (specifically carbon monoxide-CO, hydrocarbons-HC, and nitrogen oxides-NOx) in addition to the engines rotational speed (rpm), car speed, and exhaust temperature, were measured every second while driving on the specified route. Statistical analysis of the results shows that contrary to the common stereotypes, experienced drivers emitted 52% more HC and 49% more NOx than young drivers and female drivers, and male drivers emitted 14% more HC and 44% more NOx than female drivers. It also shows that CO emission is not significantly dependent on age, gender, nor driving conditions. Finally, driving through low-speed segments emits significantly higher HC (79%), while driving through uphill segments emits significantly higher (98%) NOx than driving through downhill segment.Implications: This study showed that there are significant differences in vehicular emissions among drivers from different genders and age. These differences should be taking into consideration in future emission modeling studies and regulatory scenarios.

Multicomponent Emulsified Biofuels for Transport Diesel Engines

Vegetable oils are a significant raw material resource for producing biodiesel fuels. But while using vegetable oils as fuels, the coking of the combustion chamber elements and injectors’ spraying nozzles. These problems can be solved by supplying water into the combustion chamber through the injectors. The article considers an opportunity of ensuring the stable operation of the diesel engine when it is powered by multicomponent emulsified biofuels. Emulsions of petroleum diesel fuel, rapeseed oil and water were investigated. The results of experimental studies of the automotive diesel engine running on these fuels are presented. According to the test results the efficiency of using these emulsions as fuels for diesel engines was evaluated. The favorable combination of characteristics of fuel efficiency and toxicity of diesel engine exhaust gases is obtained by using an emulsion containing 57% of petroleum diesel fuel, 30% of rapeseed oil and 13% of water (by volume). At the maximum power mode, the replacement of petroleum diesel fuel with this emulsion enabled to reduce exhaust smoke opacity from 16.0 to 7.5% according to the Hartridge scale. By the modes of the thirteen-mode cycle the integral specific emission of nitrogen oxides NOx decreases from 6, 610 to 5, 552 g/(kW·h).

Research progress of low-temperature SCR denitration catalysts

Nitrogen oxide NOx (NO, NO_2, and N_2O) is one of the major pollutants in the air pollution, it can cause environmental problems such as photochemical smog, acid rain, and ozone layer destruction, which has posed threat to people's living environment and quality of life, and attracted great attention from the world. Countries made stricter emission standards for burning emissions from both fixed and mobile sources. The major denitrification technologies include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), oxidative denitrification, and activated carbon adsorption and denitrification at present. The SNCR has higher conditions in industrial applications, the main factors affecting successful operation are temperature, ammonia-nitrogen ratio, distribution of ammonia gas in the flue gas and residence time, so there were certain limitations in industrial application of SNCR. Compared with other denitrification technologies, SCR denitration technology is more widely used in industrial application, in which denitration is mostly arranged after dust removal and desulfurization, at this time, the temperature is mostly between 100~250℃. The performance of SCR denitrification in low-temperature must be improved, which is one of the most promising flue gas DeNOx technology. In this paper, the recent works on low-temperature SCR catalysts were reviewed on manganese-based catalysts, vanadium-based catalysts and carbon-based catalysts. Single-component Mn-based catalysts, supported Mn-based catalysts and composite Mn-based catalysts were reviewed, the effects of preparation of V-based catalysts on the de-dumping and denitrification mechanisms were described. The effect of transition metal doping on C-based catalysts was reviewed. The influence of H_2O and SO_2 resistance on low-temperature NH_3-SCR catalytic activity and reaction mechanism were also discussed. Finally, the virtues advantages and defects of low temperature SCR catalysts were summarized, and the future development direction was also given out. Key learning points: (1) Catalysts for different systems were reviewed. The problems of manganese-based catalysts, vanadium-based catalysts and carbon-based catalysts were analyzed. The preparation methods were used to improve the water and sulfur resistance and catalytic activity of the catalysts. (2) Denitrification mechanism. From the currently reported denitration mechanism to analyze the activity of the catalyst, it is expected that the mechanism rsearches will improve the low temperature performance of the catalyst. (3) Water and sulfur resistance of low temperature catalyst. The presence of SO_2 at low temperatures tends to result in ABS deposition.

Potential to reduce the concentrations of short-lived climate pollutants in traffic environments: A case study in a medium-sized city in Brazil

Understanding the spatio-temporal variation of short lived climate pollutants (SLCP) over cities is critical to protect public health and mitigate climate change. There is a lack of knowledge about the distribution of SLCP in South America, mainly in medium-sized cities (<1 million inhabitants). This work reports on results of a campaign conducted at several sites (street canyon, urban background, and suburban) in Londrina, Brazil. The pollution datasets (black carbon BC, nitrogen oxides NOx, ozone O3, fine particles PM2.5, and particle number PN) were analyzed by using descriptive statistics, diurnal cycles, time-space correlations, and establishing linkages with traffic rates and with wind conditions. Hourly mean (±standard deviation) BC concentrations ranged from 0.58 (±0.54) in the suburban area to 3.43 (±2.69) µg m−3 at the street canyon site (10,150 vehicles d−1 on weekdays), showing a high spatio-temporal variability even at short scales. PN (mean of 17,469 cm−3) and NOx (mean of 51.58 µg m−3) concentrations tracked BC levels and traffic rates, particularly the number of diesel buses at the canyon site. PM2.5 and O3 levels presented a lower spatial variability, with poor correlation with traffic rates in the canyon and were more tied to regional sources. NOx, BC, and PN showed the highest reduction potentials connected to the abatement of traffic emissions in the city center, particularly by targeting heavy-duty diesel vehicles. The reduction of PM2.5 and O3 concentrations is more challenging due to a significant regional contribution that requires cutting down emissions at state, national or even transboundary scales.