Reduction Of Nitrogen Oxide Emissions Research Articles

Impacts of the exhaust gas recirculation (EGR) combined with the regeneration mode in a compression ignition diesel engine operating at cold conditions

Internal combustion engines working at cold conditions lead to the production of excessive pollutant emissions levels. The use of the exhaust gas recirculation could be necessary to reduce the nitrogen oxides emissions, even at these conditions. This paper evaluates the impact of using the high-pressure exhaust gas recirculation strategy while the diesel particulate filter is under active regeneration mode on a Euro 6 turbocharged diesel engine running at low ambient temperature (−7°C). This strategy is evaluated under 40 h of operation, 20 of them using the two systems in combination. The results show that the activation of the high-pressure exhaust gas recirculation during the particulate filter regeneration process leads to a 50% nitrogen oxides emissions reduction with respect to a reference case without exhaust gas recirculation. Moreover, the modification of some engine parameters compared to the base calibration, as the exhaust gas recirculation rate, the main fuel injection timing and the post injection quantity, allows to optimize this strategy by reducing the carbon monoxide emissions up to 60%. Regarding the hydrocarbons emissions and fuel consumption, a small advantage could be observed using this strategy. However, the activation of the high-pressure exhaust gas recirculation at low temperatures can produce fouling deposits and condensation on the engine components (valve, cooler, intake manifold, etc.) and can contribute to reach saturation conditions on the particulate filter. For these reasons, the regeneration efficiency is followed during the experiments through the filter status, concluding that the use of low high-pressure exhaust gas recirculation rates in combination with the regeneration mode also allows to clean the soot particles of the particulate filter. These soot depositions are visualized and presented at the end of this work with a brief analysis of the soot characteristics and a quantitative estimation of the total soot volume produced during the experimental campaign.

A matter of time: Recovery of plant species diversity in wild plant communities at declining nitrogen deposition

AbstractAimHigh levels of nitrogen deposition have been responsible for important losses of plant species diversity. It is often assumed that reduction of ammonia and nitrogen oxide emissions will result in the recovery of the former biodiversity. In Western Europe, N deposition peaked between 1980 and 1988 and declined thereafter. In a 60‐year experiment in hay meadows, we tested the hypothesis that increasing and declining nitrogen deposition had negative, respectively, positive effects on plant species diversity.LocationWageningen, the Netherlands.MethodDuplicated plots received different fertilization treatments from 1958 onwards (control, Ca, K, P, PK, N, NPK). Productivity, soil pH and species composition were measured at regular intervals. In the control plots, the correlations between N deposition, diversity, production and soil acidification were analysed. Subsequently, we tested whether the treatment effects (e.g. N addition and liming) confirmed the hypothesized interactions.ResultsIn the control plots, soil pH, species diversity and the abundance of legumes and short forbs declined between 1958 and 1987 when atmospheric N deposition was high but recovered after 1987 when N deposition decreased. However, also in the N addition plots species diversity recovered partly after 1987, although the soil pH of the acidified soils in these plots did not. In addition, also in the limed plots diversity decreased rapidly during the first 30 years while in this treatment soil acidification was more than compensated.Main conclusionsWe conclude that declining N deposition resulted in the recovery of plant species diversity, but not in recovery of the former species composition. Time appears to be an additional, but crucial factor for the recovery of diverse, flowering meadows. Species not adapted to the new management conditions created at the start of the experiment disappeared during the first decades, while species fit for the new environment needed many years to establish.

Real-world NOx emissions from heavy-duty diesel, natural gas, and diesel hybrid electric vehicles of different vocations on California roadways

This study assessed the real-world nitrogen oxide (NOx) emissions from 50 heavy-duty vehicles of different vocations and engine technologies using portable emissions measurement systems (PEMS). This is one of the most comprehensive in-use emissions studies conducted to date, which played a key role in the development of CARB's (California Air Recourses Board) updated EMission FACtor (EMFAC) model, especially for natural gas vehicles. In-use emissions testing was performed on school and transit buses, refuse haulers, goods movement vehicles, and delivery vehicles while were driven over their normal operating routes in the South Coast Air Basin. Engine technologies included diesel engines with and without selective catalytic reduction (SCR) systems, compressed natural gas (CNG) engines and liquified petroleum gas (LPG) engines, and SCR-equipped diesel hybrid electric vehicles. For most vehicles, the in-use NOx emissions were higher than the certification standards for the engine. Diesel vehicles generally showed higher brake-specific NOx emissions compared to the CNG vehicles. NOx emissions were strongly dependent on the SCR temperature, with SCR temperatures below 200 °C resulting in elevate brake-specific NOx. The 0.02 g/bhp-hr certified CNG vehicles showed the largest reductions in NOx emissions. The diesel hybrid electric vehicles showed important distance-specific NOx benefits compared to the conventional diesel vehicles, but higher emissions compared to the CNG and LPG vehicles. Overall, average NOx reductions were 75%, 94%, 65%, 79%, respectively, for the 0.2 CNG, 0.02 CNG, diesel hybrid electric, and LPG vehicles compared to diesel vehicles, due in part to some diesel vehicles with particularly high emissions, indicating that the widespread implementation of advanced technology and alternative fuel vehicles could provide important NOx reductions and a path for meeting air quality targets in California and elsewhere.

Can the electricity price subsidy policy curb NOX emissions from China's coal-fired power industry? A difference-in-differences approach

Air pollution currently poses a serious threat to human health and sustainable development in China. In an attempt to reduce nitrogen oxides (NOX) emissions which are the major anthropogenic contributors to air pollution, China initiated an electricity price subsidy (EPS) policy in November 2011 for incentivizing coal-fired power plants to install denitrification units. However, the effectiveness of the policy in the reduction of NOX emissions and its sustainability are yet to be investigated. This study attempts to examine the effects of the EPS policy on NOX emissions and NOX removal, based on a panel-data set covering 113 prefectural-level cities in China during 2008–2015. Using a difference-in-differences (DID) regression model, we find that for each additional power plant in cities, the EPS policy significantly reduces NOX emissions by 1.1% and increases NOX removal by 2.8%. Furthermore, the results reveal that the overall effect of the EPS policy shows a positive trend with time accompanied by an increase in price subsidy, indicating that the efficacy of the policy designed for the reduction of harmful air pollutants is sustainable. In particular, we confirm that compensating for the construction and operation costs of denitrification units is an effective mechanism which encourages the coal-fired power plants to invest more in such units. The findings of the study accentuate the significant implication that economic-incentive policies play a crucial role in combating air pollution and environmental degradation.

Effects of fuel oxygenation and ducted fuel injection on the performance of a mixing-controlled compression-ignition optical engine with a two-orifice fuel injector

This paper describes results from an optical-engine investigation of oxygenated fuel effects on ducted fuel injection (DFI) relative to conventional diesel combustion (CDC). Three fuels were tested: a baseline, non-oxygenated No. 2 emissions certification diesel (denoted CFB), and two blends containing potential renewable oxygenates. The first oxygenated blend contained 25 vol% methyl decanoate in CFB (denoted MD25), and the second contained 25 vol% tri-propylene glycol mono-methyl ether in CFB (denoted T25). Whereas DFI and fuel oxygenation primarily curtail soot emissions, intake-oxygen mole fractions of 21% and 16% were employed to explore the potential additional beneficial impact of dilution on engine-out emissions of nitrogen oxides (NOx). It was found that DFI with an oxygenated fuel can attenuate soot incandescence by ~100X (~10X from DFI and an additional ~10X from fuel oxygenation) relative to CDC with conventional diesel fuel, regardless of dilution level and without large effects on other emissions or efficiency. This breaks the soot/NOx trade-off with dilution, enabling simultaneous reductions in both soot and NOx emissions, even with conventional diesel fuel. Significant cyclic variability in soot incandescence for both CDC and DFI suggests that additional improvements in engine-out soot emissions may be possible via improved control of in-cylinder mixture formation and evolution.

Methods for reducing nitrogen oxide emissions in steam generators of thermal power plants

Main problem: Ensuring environmental safety of thermal power plants by reducing emissions of harmful substances, in particular nitrogen oxides. When all types of fossil fuel, including solid fuel, are burned, nitrogen oxides are formed in the boilers of TPPs. The sources of their formation are air nitrogen and nitrogen- containing components of the organic matter of the fuel. As you know, they adversely affect the health of humans, plants and animals. Therefore, it became necessary to consider and analyze methods to reduce these emissions. Purpose: To review and analyze various ways to reduce nitrogen oxide emissions and propose a new scheme for reducing these emissions by recirculating flue gases. Methods: This is achieved due to the fact that in the known method for purifying the flue gases of steam generators from nitrogen oxides by lowering the temperature in the furnace of the steam generator by supplying flue gases with a temperature below the temperature in the furnace of the steam generator, it is proposed that the flue gases be fed into the furnace of the steam generator after ash cleaning. At the same time, as a result of the supply of recirculated gas cooled after filtering and passing through the main smoke exhauster into the combustion chamber, having a temperature of 110-170 °C, in comparison with the initial version, a greater decrease in temperature in the furnace of the steam generator occurs, which in turn leads to a decrease in the flue gases of oxides nitrogen, since the chemical reaction of their formation goes with the absorption of heat. Results and their importance: The technical result at the proposed method of cleaning from nitrogen oxides is to reduce the consumption of electricity by eliminating the collateral wear of the recirculation gas duct, due to the cleaning of time gases from ash (a requirement of the rules of technical operation of PTE).

The effects of ceria loading on three-way catalysts for passive SCR operation

Passive SCR systems, which employ both a three-way catalyst and SCR catalyst, are effective for the reduction of nitrogen oxide (NOx) emissions from lean burn gasoline engines. However, questions remain regarding the effect of three-way catalyst formulations on their performance in these systems. Here, Pd/CeOx/Al2O3 catalysts with variable CeOx loading were synthesized, characterized, and evaluated to determine the effects of CeOx on catalyst performance. While a small amount of ceria was beneficial for promoting essential reactions, excess ceria was detrimental due to the increase in oxygen storage capacity. Additionally, insights into potential reaction pathways for NH3 production were determined.

Oxide Emissions Reduction from Combustion Control in a Diesel Engine

The authors showed that the European Union norms for the toxicity of exhaust gases (Euro 1 – Euro 5) contributed to the reduction of main harmful components emissions by several times. In foreign countries, Stage and Tier regulations applied to tractor equipment, which also limited the content of toxic components at the legislative level.(Research purpose) To reduce the content of nitrogen oxides in exhaust gases by more efficient regulation of the fuel charge distribution in the gas-diesel engine cylinder, changes in the concentration of diesel and gas fuel in certain zones, as well as the use of exhaust gas recirculation.(Materials and methods) The authors analyzed the results of modeling the formation of nitrogen oxides by controlling the workflow in the gas-diesel modification of the diesel engine. In the calculations, the geometric parameters of the D-120 engine, operating at 2000 revolutions per minute, with a filling of 0.6-0.9 volume, were used. The average excess air ratio for the charge was 1.2-3.0, and the excess air ratios for the gas-air mixtures did not exceed 1.2-2.5.(Results and discussion) Using the computational model, the authors estimated the parameters at different pressures at the engine inlet within 0.05-0.09 megapascals, as well as with an increase in the residual gas coefficient in the range of 5-15 percent with a decrease in the concentration of nitrogen oxides from 2500 to 1100 parts per million. Experiments showed that when the power changed from 100 to 20 percent, the nitrogen oxides concentration decreased from 1940 to 800 parts per million.(Conclusions) The authors confirmed the adequacy of the calculation model. They determined that a 40-50 percent reduction in the nitrogen oxide concentration in exhaust gases was achieved with various layering schemes in the combustion chamber. They found that the standards for carbon monoxide, hydrocarbons and nitrogen oxides would require mixed engine regulation. It was proved that recirculation of 15 percent of exhaust gases could reduce nitrogen oxide emissions by another 50 percent.

On the Relevancy of Observed Ozone Increase during COVID-19 Lockdown to Summertime Ozone and PM2.5 Control Policies in China.

In February 2020, China’s strict lockdown policies led to significant reductions in anthropogenic nitrogen oxides (NOx) emissions, and notable increases in surface ozone (O3) followed in many urban areas, raising concerns about potential rises in summertime O3 due to NOx emission controls. On the basis of O3 isopleths from a series of air quality simulations under different levels of NOx and volatile organic compound (VOC) emission reductions, we found that such concerns are not necessary. As NOx emissions have been reduced in recent years for particulate matter control, future NOx reductions are generally favorable for summertime maximum daily average 8-h (MDA8) O3 reductions. Decreases in summertime O3 due to NOx reductions will also lead to lower atmospheric oxidation capacity, characterized by decreased OH and NO3 concentrations, resulting in further reduction of secondary inorganic aerosols (nitrate, sulfate, and ammonium ion, NSA) formation. VOC emission reductions help to further reduce MDA8 O3 and are needed to control HCHO and primary air toxics simultaneously, but they are ineffective in reducing NSA. This study indicates that a nationwide NOx emission reduction policy has great potential in controlling O3 and PM2.5 simultaneously. However, its effectiveness could be greatly reduced when applied on a limited spatial scale.

Seasonal variations in the highly time-resolved aerosol composition, sources and chemical processes of background submicron particles in the North China Plain

Abstract. For the first time in the North China Plain (NCP) region, we investigated the seasonal variations in submicron particles (NR-PM1) and their chemical composition at a background mountainous site of Xinglong using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer. The average concentration of NR-PM1 was highest in autumn (15.1 µg m−3) and lowest in summer (12.4 µg m−3), with a greater abundance of nitrate in spring (34 %), winter (31 %) and autumn (34 %) and elevated organics (40 %) and sulfate (38 %) in summer. PM1 in Xinglong showed higher acidity in summer and moderate acidity in spring, autumn and winter, with average pH values of 2.7±0.6, 4.2±0.7, 3.5±0.5 and 3.7±0.6, respectively, which is higher than those estimated in the United States and Europe. The size distribution of all PM1 species showed a consistent accumulation mode peaking at approximately 600–800 nm (dva), indicating a highly aged and internally mixed nature of the background aerosols, which was further supported by the source appointment results using positive matrix factorization and multilinear engine analysis. Significant contributions of aged secondary organic aerosol (SOA) in organic aerosol (OA) were resolved in all seasons (>77 %), especially in summer. The oxidation state and the process of evolution of OAs in the four seasons were further investigated, and an enhanced carbon oxidation state (−0.45–0.10) and O/C (0.54–0.75) and OM/OC (1.86–2.13) ratios – compared with urban studies – were observed, with the highest oxidation state appearing in summer, likely because of the relatively stronger photochemical processing that dominated the formation processes of both less oxidized OA (LO-OOA) and more oxidized OA (MO-OOA). Aqueous-phase processing also contributed to the SOA formation and prevailed in winter, with the share to MO-OOA being more important than that to LO-OOA. In addition, regional transport also played an important role in the variations in SOA. Especially in summer, continuous increases in SOA concentration as a function of odd oxygen (Ox=O3+NO2) were found to be associated with the increases in wind speed. Furthermore, backward trajectory analysis showed that higher concentrations of submicron particles were associated with air masses transported short distances from the southern regions in all four seasons, while long-range transport from Inner Mongolia (western and northern regions) also contributed to summertime particulate pollution in the background areas of the NCP. Our results illustrate that the background particles in the NCP are influenced significantly by aging processes and regional transport, and the increased contribution of aerosol nitrate highlights how regional reductions in nitrogen oxide emissions are critical for remedying occurrence of nitrate-dominated haze events over the NCP.

Effects of n-heptane/toluene/ethanol ternary fuel blends on combustion, operating range and emissions in premixed low temperature combustion

Low temperature combustion engines are a new combustion model that the reduction of nitrogen oxide emissions and the increasing of the thermal efficiency can be observed simultaneously. In addition, the problem of misfire at low engine loads and knocking at high engine loads occurs. The fuels have low octane number can be used to eliminate the misfire problem at low engine loads, and the fuels have high octane number can be used to eliminate knocking problem at high engine loads. In this study, the operating ranges of low and high reactivity fuel mixtures with different chemical properties were experimentally investigated in a low temperature combustion engine. While high reactivity n-heptane, T10 and E10 fuels were used, it was seen to be suitable for HCCI strategy in wider and leaner mixing conditions, while low reactivity E20 and E30 showed good performance at high engine loads close to the knocking zone. The highest brake thermal efficiency was obtained as 44.5% with E30 fuel under extremely lean mixture conditions (ʎ = 2.95). While E20 fuel shows a good performance like E30, the fact that most of the combustion takes place before TDC in the use of high reactivity fuel caused low efficiency due to knock and heat losses. It can be stated that ethanol has low reactivity needs high inlet air temperature, high compression ratio or combustion improving additives such as n-heptane and toluene to be used in HCCl applications. The results obtained support the idea of fuel flex vehicles for the current engine.

Mitigating NOX emissions does not help alleviate wintertime particulate pollution in Beijing-Tianjin-Hebei, China.

Stringent mitigation measures have reduced wintertime fine particulate matter (PM2.5) concentrations by 42.2% from 2013 to 2018 in the Beijing-Tianjin-Hebei (BTH) region, but severe PM pollution still frequently engulfs the region. The observed nitrate aerosols have not exhibited a significant decreasing trend and constituted a major fraction (about 20%) of the total PM2.5, although the surface-measured NO2 concentration has decreased by over 20%. The contributions of nitrogen oxides (NOX) emissions mitigation to the nitrate and PM2.5 concentrations and how to alleviate nitrate aerosols efficiently under the current situation still remains elusive. The WRF-Chem model simulations of a persistent and heavy PM pollution episode in January 2019 in the BTH reveal that NOX emissions mitigation does not help lower wintertime nitrate and PM2.5 concentrations under current conditions in the BTH. A 50% reduction in NOX emissions only decreases nitrate mass by 10.3% but increases PM2.5 concentrations by 3.2%, because the substantial O3 increase induced by NOX mitigation offsets the HNO3 loss and enhances sulfate and secondary organic aerosols formation. Our results are further consolidated by the occurrence of severe PM pollution in the BTH during the COVID-19 outbreak, with a significant reduction in NO2 concentration. Mitigation of NH3 emissions constitutes the priority measure to effectively lower the nitrate and PM2.5 concentrations in the BTH under current conditions, with 35.5% and 12.7% decrease, respectively, when NH3 emissions are reduced by 50%.

Multi-objective optimization design and control of plug-in hybrid electric vehicle powertrain for minimization of energy consumption, exhaust emissions and battery degradation

Plug-in hybrid electric vehicles (PHEV) offer an attractive alternative to achieve the ambitious goals set by strong policies focused on near-term air quality and fuel-efficient road transportation. This paper provides a comprehensive study regarding the PHEV’s optimum powertrain design, by means of a multi-criteria analysis carried out by the interactive adaptive-weight genetic algorithm approach. The optimization aims to simultaneously minimize the PHEV’s fuel consumption, exhaust emissions, electric powertrain size, battery state of health, charging time and costs. To achieve these objectives, several PHEV’s design parameters are optimized such as in-wheel electric motors’ torque curves, battery voltage and capacity. The drivetrain is also optimized according to the determination of the best configuration of gearbox and differential gear ratios, taking into account constructive constraints. Furthermore, the fuzzy logic controllers responsible for the engine/electric motors power-split management and gear shifting control are included in the multi-objective optimization in order to define the best membership functions, rules and respective weights. To guarantee robust solutions, the PHEV is optimized under different driving conditions, which is given by the combination of the FTP-75, HWFET and US06 driving cycles. To evaluate the optimum PHEV performance, it is also simulated under the WLTC driving cycle and a real-world driving cycle based on the Campinas city. The best trade-off configuration results in 39.57% decrease in vehicle travel cost along with 43.39% carbon monoxide (CO), 45.13% unburned hydrocarbons (HC) and 72.64% nitrogen oxides (NOx) emissions reduction under the combined driving cycle.

Prediction of nitrogen oxide emission concentration in cement production process: a method of deep belief network with clustering and time series.

The concentration of nitrogen oxide (NOx) emissions is an important environmental index in the cement production process. The purpose of predicting NOx emission concentration during cement production is to optimize the denitration process to reduce NOx emission. However, due to the problems of time delay, nonlinearity, uncertainty, and data continuity in the cement production process, it is difficult to establish an accurate NOx concentration prediction model. In order to solve the above problems, a NOx emission concentration prediction model using a deep belief network with clustering and time series features (CT-DBN) is proposed in this paper. Particularly, to improve data sparsity and enhance data characteristics, a clustering algorithm is introduced into the model to process the original data of each variable; the time series containing delay information are introduced into the input layer, which combines previous and current variable data into time series data to eliminate the influence of the time delay on the prediction of NOx emission concentration. In addition, restricted Boltzmann machine (RBM) is used to extract data features, and a gradient descent algorithm is used to reversely adjust network parameters to establish a deep belief network model (DBN). Experiments prove that the method in this paper has higher accuracy, stronger stability, and better generalization ability in predicting NOx emission concentration in cement production. The CT-DBN model realizes the accurate prediction of NOx emission concentration, provides guidance for denitration control, and reduces NOx emissions.

Experimental investigation to enhance the low‐temperature nitrogen oxide emission reduction in biodiesel exhaust using selective catalytic reduction with direct ammonia injection and manganese cerium zirconia catalyst

AbstractSelective catalytic reduction (SCR) employs AdBlue, a reducing agent over a catalytic surface to reduce the oxides of nitrogen (NOx) emission in diesel engines. SCR's inherent problem is its poor cold start performance at exhaust temperatures below 150°C. In the current work, the researcher has discussed the investigation of two techniques to enhance low‐temperature NOx conversion and combined them to achieve the best results. First, AdBlue injection was replaced by gaseous ammonia injection. The gaseous ammonia was generated by heating solid ammonia precursor materials such as solid urea and ammonium carbonate. Second, to improve the catalytic performance, MnCeZrOx catalysts were introduced instead of conventional CuZ catalysts. MnCeZrOx were prepared in the laboratory using its component materials. The prepared catalyst was tested through SEM and EDAX analysis. The newly developed SCR system was tested and compared with a conventional Adblue‐CuZ SCR. The results revealed with diesel fuel at exhaust temperatures below 150°C the ammonia‐MnCeZrOx SCR system gave a 90% increase in NOx reduction compared to the conventional system. With biodiesel blend jatropha B20 the conversion was greater than 80% from 100 to 150°C. A maximum NOx conversion of 95% was obtained for diesel and 93% for jatropha Biodiesel blend B20.

Dynamic spatial analysis of NO2 pollution over China: Satellite observations and spatial convergence models

Owing to rapid urbanization and industrialization over decades, nitrogen dioxide (NO2) has become a serious air pollutant in China. The Chinese government has proposed a series of strict strategies for the reduction of nitrogen oxides (NOx) emissions. This research studies the spatio-temporal characteristics of NO2 pollution over China from October 2004 to June 2020 based on satellite observations. The findings are as follows. Overall, NO2 vertical column densities (VCDs) first increased from 2005 to 2012, and then displayed a decreasing trend after 2013. In addition, the centroid of NO2 values over China during the period of 2006–2010 was located in north Henan and shifted towards the west, suggesting that the NO2 pollution in the eastern region decreased more rapidly than that in the western region. On the other hand, another important aim of this research is to forecast the trajectory of dynamic spatial differences of NO2 pollution. Technically, we investigated σ and β convergence of the NO2 pollution across Chinese cities. The results of the σ convergence test based on standard deviations of annual mean NO2 VCDs showed that, from 2005 to 2011, the differences in NO2 VCDs widened year by year. However, since 2013, we have witnessed a narrowing gap of NO2 pollution among different cities. We found that the σ convergence results based on the kernel density estimates revealed that the convergence of NO2 pollution across cities are heavily dependent on the improvements of the cities with high levels of NO2 concentrations. Besides, the results of the β convergence models confirmed the absolute and conditional β convergence. In addition, we found that the convergence speed in winter was faster than in summer.

Study of Indicators of CI Engine Running on Conventional Diesel and Chicken Fat Mixtures Changing EGR

This article presents a change in the indicators of a compression ignition (CI) engine by replacing conventional diesel fuel (D100) with pure chicken fat (F100) and mixtures of these fuels. Mixtures of diesel and fat with volume ratios of 70/30, 50/50 and 30/70 were used. Research of the fuel properties was conducted. In order to reduce the fuel viscosity, blends of fat and diesel were heated. The experimental research was conducted at different engine loads with exhaust gas recirculation (EGR) both off and on. The conducted analysis of the combustion process revealed a significant change in the rate of heat release (ROHR) when replacing diesel with chicken fat. Chicken fat was found to increase the CO2 and CO emissions, leaving hydrocarbon (HC) emissions nearly unchanged. Having replaced the D100 with diesel and chicken fat mixtures or F100, a significant reduction in smoke and nitrogen oxide (NOx) emissions was observed when EGR was off. When EGR was on, the smoke level increased, but the blends with chicken fat reduced it significantly, and the increased fat content in the fuel mixture reduced the NOx emissions. The engine’s brake specific fuel consumption (BSFC) increased while the brake thermal efficiency (BTE) decreased, having replaced conventional diesel with chicken fat due to differences in the fuel energy properties and the combustion process.

Nitrogen oxide emissions reducing in cement production

In the European Union, the Russian Federation, as well as in a number of other countries, cement production is regulated by legislation on the best available technologies. Mandatory requirements (technological parameters, BAT-AELs) are imposed, first of all, on the emissions limitation of inorganic dust, nitrogen and sulfur oxides. The majority of Russian cement plants are currently characterized by the nitrogen oxide emissions state-established technological indicators‘ excess. The technological indicators of the best available technologies and methods for reducing nitrogen oxide emissions operating in the Russian Federation and the EU countries are considered. It is demonstrated that the most efficient technologies are the staged fuel combustion and selective non-catalytic reduction (SNCR) of nitrogen oxides.

Greater fuel efficiency is potentially preferable to reducing NOx emissions for aviation\u2019s climate impacts

Aviation emissions of nitrogen oxides (NOx) alter the composition of the atmosphere, perturbing the greenhouse gases ozone and methane, resulting in positive and negative radiative forcing effects, respectively. In 1981, the International Civil Aviation Organization adopted a first certification standard for the regulation of aircraft engine NOx emissions with subsequent increases in stringency in 1992, 1998, 2004 and 2010 to offset the growth of the environmental impact of air transport, the main motivation being to improve local air quality with the assumed co-benefit of reducing NOx emissions at altitude and therefore their climate impacts. Increased stringency is an ongoing topic of discussion and more stringent standards are usually associated with their beneficial environmental impact. Here we show that this is not necessarily the right direction with respect to reducing the climate impacts of aviation (as opposed to local air quality impacts) because of the tradeoff effects between reducing NOx emissions and increased fuel usage, along with a revised understanding of the radiative forcing effects of methane. Moreover, the predicted lower surface air pollution levels in the future will be beneficial for reducing the climate impact of aviation NOx emissions. Thus, further efforts leading to greater fuel efficiency, and therefore lower CO2 emissions, may be preferable to reducing NOx emissions in terms of aviation’s climate impacts.

Influence of plasma-chemical products on process stability in a low-emission gas turbine combustion chamber

Abstract The article describes the stability of gaseous fuel combustion in gas turbine low-emission combustion chambers with the plasma-chemical assistance. The mathematical model of unsteady processes in a low-emission combustion chamber with a plasma-chemical stabilizer that takes into consideration the impact of low-temperature plasma on aerodynamics flow in a combustion chamber and the characteristics of heat release is developed. A methodology of a numerical experiment concerning the stability of gaseous fuel combustion in a combustion chamber with plasma assistance using computational fluid dynamics, which enhances the efficiency of designing and adjustment, is proposed. Practical recommendations for improvement of stability of a gas turbine combustion chamber with partially premixed lean fuel–air mixtures, working on gaseous fuels, are developed. They allow to reduce pressure fluctuations inside the flame tube by 10–35%, to decrease spectral power of static pressure in the flame tube in 1.5–2.0 times, to reduce nitrogen oxide emission up to 33.6 ppm in the exit section while retaining a carbon monoxide emission level, that corresponds modern international ecological standards.