Nitrogen Oxide Emissions Research Articles

Operation of a Compression Ignition Engine at Idling Load Under Simulated Cold Weather Conditions

Abstract Heavy-duty compression ignition (CI) engines can be subject to long periods of idling during their duty cycles. In colder climates, getting the engine and exhaust aftertreatment (EAT) system to ideal operating temperatures can be challenging under such idling and low load conditions. This may lead to high emissions of criteria pollutants especially nitrogen oxides (NOx). Increasing the engine load and idling speed may help mitigate NOx emissions but typically leads to higher greenhouse gas emissions. Therefore, the objective of this study is to evaluate the performance of a heavy-duty CI engine operating at various idling conditions and determine suitability for exhaust aftertreatment system operation. Tests are conducted on a heavy-duty single cylinder CI research engine fueled with diesel. As per the United States' (U.S.) Code of Federal Regulations (CFR), CI engines can be certified for the optional Clean Idle NOx emission standard. A corresponding two-mode Clean Idle Test (CIT) is specified in CFR which requires the engine to be operating in fully warmed-up condition at two engine speeds. Steady-state tests are conducted at these two engine speeds of 650 and 1100 rpm, and cold weather operation is simulated by operating the engine at suboptimal coolant, lubricant, and intake air temperatures. The steady-state tests are used to determine suitable diesel injection timing for performing the CIT under standard and simulated cold weather conditions. At the lowest load and 650 rpm idling speed, use of multiple injections and exhaust gas recirculation (EGR) are insufficient for raising the exhaust gas temperature above 200 °C. A combination of higher load, EGR, and 1100 rpm idling speed can create conditions for light-off selective catalytic reduction (LO-SCR) operation at the expense of higher fuel consumption. The modified CIT results show that the optional Clean Idle NOx emission standards can be met with the use of EGR at both test modes. The mode 2 conditions at 1100 rpm may allow LO-SCR activation as well. There are also distinct differences between results under fully and partially warmed-up conditions.

Production of biodiesel from hemp oil and oleic acid with sulfonated camphor catalysts is to be evaluated with controlled tests in a diesel engine

Abstract This research examines the performance variables, combustion, and the amounts of NOx, CO, HC, and K emissions in a diesel engine, using blends of hemp biodiesel and oleic acid biodiesel with conventional diesel. To obtain biodiesel from hemp oil and oleic acid, a heterogeneous sulfonated camphor catalyst (CASU-AL) was used for the transesterification of hemp oil and the esterification of oleic acid respectively. Several characterization tests were performed on the CASU-AL catalyst such as the acid-base titration method for the quantification of acid sites, XRD analysis to determine the areas of the carbonaceous material, images and composition of CASU-AL were obtained with SEM and EDX, the porosity characteristics and surface properties were assessed with BET analysis. Constant operating conditions were used in the autogenous reactor with a temperature of 200 °C, a reaction time of 23 min, and a quantity of sulfonated camphor catalyst of 0.033 % w. Several analyses were applied to the CASU-AL, several mixtures were made with conventional diesel, and different biodiesels were obtained in the laboratory. The mixtures were conventional diesel (DIE-100), hemp oil biodiesel (BAC-100), oleic acid biodiesel (BAO-100), Diesel-BAC mixture with 30 % hemp oil biodiesel (MDBAC-30), and Diesel-BAO mixture with 30 % oleic acid biodiesel (MDBAO-30). For the tests in a diesel engine, three speed zones were selected in the engine to identify the behavior at low speed at 1,200 rpm, medium speed at 1,400 rpm, and high speed at 1800 rpm. Combustion tests reveal that no significant variation is observed in the characteristics and performance of the diesel engine, however, in the gaseous products derived from combustion, significant reductions in carbon monoxide, unburned hydrocarbon, and an increase in nitrogen oxide emissions were achieved when using DIE-100 compared to BAC-100 and BAO-100. The tests showed a reduction in NOx, CO, HC, K, and smoke emissions when testing MDBAC-30 and MDBAO-30 in a laboratory diesel engine. A comparison of the properties of hemp oil-oleic acid biodiesels BAC-100 and BAO-100 with conventional diesel DIE-100 revealed that the different biodiesels used could be used alone or in a blend of 70 % diesel and 30 % biodiesel to fuel diesel engines by decreasing air pollutants and promoting lubricity in the engine. Our findings revealed that MDBAC-30 and MDBAO-30 showed the best engine performance and lowest emissions among all the tested fuels. In other words, MDBAC-30 and MDBAO-30 are the ideal fuel blends for diesel engines and do not require any modification to the engine.

Experimental investigation of nano-enhanced Azolla biodiesel blends for improved diesel engine performance and emission mitigation

Abstract This study investigates the performance and emission characteristics of a diesel engine fueled with Azolla microphylla biodiesel blends and the effects of aluminium oxide (Al2O3) and copper oxide (CuO) nanoparticles as fuel additives. Azolla microphylla, an aquatic fern, was used to produce biodiesel through a transesterification process. Diesel fuel was blended with Azolla biodiesel in ratios of 10:90 (B10), 20:80 (B20), and 30:70 (B30). Engine performance parameters, including brake thermal efficiency (BTE), brake-specific fuel consumption (BSFC), and emissions of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and smoke, were evaluated. The results showed that the B30 blend exhibited the highest BTE under maximum load conditions. To address the high viscosity and poor combustion performance of higher biodiesel blends, Al2O3 and CuO nanoparticles were added to the B30 blend at concentrations of 50 ppm and 100 ppm. The B30 blend with 100 ppm Al2O3 nanoparticles demonstrated the highest BTE and the lowest emissions of HC, CO, CO2, and smoke compared to the other test blends. The improved combustion and reduced emissions were attributed to the enhanced heat transfer and catalytic properties of the Al2O3 nanoparticles. These findings suggest that Azolla biodiesel, especially when combined with Al2O3 nanoparticles, can be a viable and sustainable alternative to conventional diesel fuel.

The possibility of reducing the anthropogenic load of diesel engines on the environment by changing the compression ratio

The article is devoted to solving environmental problems arising from the operation of mobile energy vehicles with diesel engines in the agro-industrial sector and installed on cars, tractors, combines. Contrary to all forecasts, the use of environmentally friendly engines capable of competing with piston engines is limited in agricultural production, therefore, solving the problem of reducing harmful emissions from exhaust gases of diesel engines used in agriculture is very important and relevant. The research is aimed at solving one of the key tasks of our time – reducing the anthropogenic load from harmful emissions of diesel engines on the environment by changing the compression ratio. As a result of the test, it was found that an increase in the compression ratio from 13.5 to 15.5 leads to a decrease in emissions from exhaust gases of solid particles (PM), hydrocarbons (CxHy) and carbon monoxide (CO), however, over the entire load characteristic from Pe =0 to Pe=1.24 MPa at 1900 min-1 emissions of nitrogen oxides (NOx) increases. Emissions of particulate matter from exhaust gases are reduced from 0.122 to 0.063. When the compression ratio changes from 13.5 to 15.5, the estimated values change: for nitrogen oxides – by 1.88 times; for carbon monoxide – by 1.22 times; for hydrocarbons – by 1.35 times; for solid particles – by 1.15 times. The evaluation results showed that the values of the anthropogenic load were Htn = 78.31 ut/g with serial configuration at = 13.5 and Htn = 90.4 ut/g at = 14.5. This indicates a decrease of 1.15 times with a decrease to 13.5. In order to obtain the best results in reducing the anthropogenic load on the environment, it is recommended to use complex methods, for example, simultaneous changes in the degree of compression and catalytic neutralization.

Urban ozone formation and sensitivities to volatile chemical products, cooking emissions, and NOx upwind of and within two Los Angeles Basin cities

Abstract. Volatile chemical products (VCPs) and other non-traditional anthropogenic sources, such as cooking, contribute substantially to the volatile organic compound (VOC) budget in urban areas, but their impact on ozone formation is less certain. This study employs Lagrangian box modeling and sensitivity analyses to evaluate ozone response to sector-specific VOC and nitrogen oxide (NOx) emissions in two Los Angeles (LA) Basin cities during the summer of 2021. The model simulated the photochemical processing and transport of temporally and spatially gridded emissions from the FIVE-VCP-NEI17NRT inventory and accurately simulates the variability and magnitude of O3, NOx, and speciated VOCs in Pasadena, CA. VOC sensitivity analyses show that anthropogenic VOCs (AVOC) enhance the mean daily maximum 8 h average ozone in Pasadena by 13 ppb, whereas biogenic VOCs (BVOCs) contribute 9.4 ppb. Of the ozone influenced by AVOCs, VCPs represent the largest fraction at 45 %, while cooking and fossil fuel VOCs are comparable at 26 % and 29 %, respectively. NOx sensitivity analyses along trajectory paths indicate that the photochemical regime of ozone varies spatially and temporally. The modeled ozone response is primarily NOx-saturated across the dense urban core and during peak ozone production in Pasadena. Lowering the inventory emissions of NOx by 25 % moves Pasadena to NOx-limited chemistry during afternoon hours and shrinks the spatial extent of NOx saturation towards downtown LA. Further sensitivity analyses show that using VOCs represented by a separate state inventory requires steeper NOx reductions to transition to NOx sensitivity, further suggesting that accurately representing VOC reactivity in inventories is critical to determining the effectiveness of future NOx reduction policies.

Investigating processes influencing simulation of local Arctic wintertime anthropogenic pollution in Fairbanks, Alaska, during ALPACA-2022

Abstract. Lagrangian tracer simulations are deployed to investigate processes influencing vertical and horizontal dispersion of anthropogenic pollution in Fairbanks, Alaska, during the Alaskan Layered Pollution and Chemical Analysis (ALPACA) 2022 field campaign. Simulated concentrations of carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen oxides (NOx), including surface and elevated sources, are the highest at the surface under very cold stable conditions. Pollution enhancements above the surface (50–300 m) are mainly attributed to elevated power plant emissions. Both surface and elevated sources contribute to Fairbanks' regional pollution that is transported downwind, primarily to the south-west, and may contribute to wintertime Arctic haze. Inclusion of a novel power plant plume rise treatment that considers the presence of surface and elevated temperature inversion layers leads to improved agreement with observed CO and NOx plumes, with discrepancies attributed to, for example, displacement of plumes by modelled winds. At the surface, model results show that observed CO variability is largely driven by meteorology and, to a lesser extent, by emissions, although simulated tracers are sensitive to modelled vertical dispersion. Modelled underestimation of surface NOx during very cold polluted conditions is considerably improved following the inclusion of substantial increases in diesel vehicle NOx emissions at cold temperatures (e.g. a factor of 6 at −30 °C). In contrast, overestimation of surface SO2 is attributed mainly to model deficiencies in vertical dispersion of elevated (5–18 m) space heating emissions. This study highlights the need for improvements to local wintertime Arctic anthropogenic surface and elevated emissions and improved simulation of Arctic stable boundary layers.

The Impact of Air Pressure on Performance, Combustion Behavior, and Emissions of An Air-assisted Port Fuel Injection HCCI Engine

Low-temperature combustion is achieved through homogeneous charge compression ignition (HCCI), which lowers the emission of nitrogen oxides (NOx) associated with diesel engines. HCCI combustion faces various obstacles, including combustion phasing, high hydrocarbon (HC) emissions, a limited operation range, and homogeneous mixture preparation. This research aims to compare the influence of air pressure in an air-assisted injector on performance, combustion behavior, and emissions. The experiment was conducted at an intake temperature of 50oC, speed of 2100 RPM and air pressures of 3,4 and 5 bar. Intake air was heated in an intake pipe heater, and an air regulator regulated the air pressure. An air assist pressure of 5 bar resulted in the highest brake thermal efficiency, ranging from 20.5% to 23.3%. For brake-specific fuel consumption, an air pressure 3 bar produced higher values ranging from 410.8 g/kWh to 500.8 g/kWh. The in-cylinder pressure for 3,4 and 5 bar pressure exceeds 80 bar at 25% load. Air pressure of 4 bar recorded the lowest HC, ranging from 50 to 75 ppm. For NOx emission, 3 bar air pressure showed the lowest levels, ranging from 8 to 12 ppm across the tested loads. The highest carbon monoxide (CO) percentage was recorded at 5 bar air pressure at 20% load with a CO value of 0.53%. At 20% and 25% load, the combustion profile displayed a three-stage ignition process, indicating the occurrence of diffusive combustion.

Development of the NO2 ratio model for heavy-duty diesel engine two-stage SCR aftertreatment system

A diesel oxidation catalyst (DOC) outlet nitrogen dioxide (NO2) ratio model based on the model-based calibration (MBC) method was proposed, which is an important part of the two-stage selective catalytic reduction (SCR) control strategy for heavy-duty diesel engines. Emissions regulations for heavy-duty diesel engines around the world have become more stringent in limiting nitrogen oxide (NOx), especially when the engine is cold starting, which brings serious challenges to the aftertreatment system. The two-stage SCR system with the close coupled selective catalytic reduction-diesel oxidation catalyst-diesel particulate filter-selective catalytic reduction (ccSCR-DOC-DPF-SCR) layout has the potential to achieve ultra-low NOx emissions due to its high technology maturity, but the two-stage SCR urea injection control strategy based on the chemical reaction kinetics model presents a new functional requirement for the prediction of NO2 ratio at the DOC outlet. However, experiments show that the Euro VI method based on calibration to obtain DOC outlet NO2 ratio was not suitable for the two-stage SCR system, because of the temperature delay effect of ccSCR in transient conditions. Therefore, a quadratic polynomial model using the MBC method was constructed to predict the DOC outlet NO2 ratio in the two-stage SCR system. The proposed MBC model can predict the NO2 ratio by using exhaust mass flow rate, DOC inlet temperature, and DOC inlet NOx concentration. Experiments show that the proposed MBC model has wide applicability, for the two-stage SCR system under transient conditions, whether ccSCR urea injection is enabled will not affect the accuracy of the model’s prediction of the NO2 ratio for the DOC outlet or SCR inlet.

A long-term analysis of oxidant (OX = O3 + NO2) and its local and regional levels in Tehran, Iran, a high NOx-saturated condition

Oxidant (OX), the sum of ozone (O3) and nitrogen dioxide (NO2), is used to determine nitrogen oxides (NOx)-independent regional contribution and NOx-dependent local contribution. This study investigates OX trends and its local and regional levels in Tehran, Iran using the data from 21 monitoring stations from 2012 to 2022 and satellite remote sensing data (TROPOMI) for 2022. The spatiotemporal trends of O3, NO2, and OX are first examined using ground-based and remote sensing data, and then the polar plots are employed to identify the dominant directions of OX transport and its sources. Subsequently, the local and regional contributions of OX were determined using OX-NOx relationship. The findings indicated that the OX trend is primarily affected by O3 fluctuations during the warmer months, whereas NO2 variations have a stronger correlation with OX during the remaining months. The emissions from the central zone of the city were mostly caused by the transportation fleet. The emissions from industries in the south also have a significant effect on the city’s OX concentration. Moreover, the local contribution of OX, reaching a maximum value of 0.15 ppb/ppb NOx (for both monthly and yearly analysis), contributes to the elevation of OX levels during nighttime. In contrast, the OX local contribution at daylight hours is mostly negative, with minimum values of − 0.15 ppb/ppb NOx for July and − 0.07 ppb/ppb NOx for 2012, indicating a decrease in the OX concentration with an increase in the local NOx emission. Furthermore, the OX levels, especially for daylight hours, is mostly related to its regional contribution with maximum of 100 ppb in July and 95 ppb in 2017, suggesting the necessity of considering regional emissions in developing mitigation scenarios. Lastly, our results indicate that the transportation fleet plays an undeniable role in contributing to the local emissions in Tehran.

Near‐Automated Estimate of City Nitrogen Oxides Emissions Applied to South and Southeast Asia

AbstractCities in South and Southeast Asia are developing rapidly without routine, up‐to‐date knowledge of air pollutant precursor emissions. This data deficit can potentially be addressed for nitrogen oxides (NOx) by deriving city NOx emissions from satellite observations of nitrogen dioxide (NO2) sampled under windy conditions. NO2 plumes of isolated cities are aligned along a consistent wind‐rotated direction and a best‐fit Gaussian is applied to estimate emissions. This approach currently relies on non‐standardized choice of upwind, downwind, and across‐wind distances from the city center, resulting in fits that often fail or yield non‐physical parameters. Here, we propose an automated approach that defines many combinations of distances yielding 54 distinct sampling boxes that we test with TROPOspheric Monitoring Instrument (TROPOMI) NO2 observations over 19 isolated cities in South and Southeast Asia. Our approach is efficient, uses open‐source software, is adaptable to many cities, standardizes and eliminates sensitivity to sampling box choice, increases success of deriving emissions from 40% to 60% with one sampling box to 100% (all 19 cities) with 54, and yields emissions consistent with the current manual approach. We estimate that the annual emissions range from 15 ± 5 mol s−1 for Bangalore (India) to 125 ± 41 mol s−1 for Dhaka (Bangladesh). With enhanced success of deriving top‐down emissions, we find support from comparison to past studies and inventory estimates that top‐down emissions may be biased, as the method does not adequately account for spatial and seasonal variability in NOx photochemistry. Further methodological development is needed for enhanced accuracy and use to derive sub‐annual emissions.

Experimental investigation of bluff body geometry effects on nitrogen oxides emissions from Cambridge stratified burner

In this study, a series of experiments are done to analyze the effect of bluff body geometry on the NOx reduction of a natural gas-air stratified swirl burner. The stratified burner of Cambridge University is chosen to study the mentioned geometrical effect, and the geometry modification of bluff body is used as a simple method for NOx reduction, which can be easily applied to the systems using these burners, including gas turbines. The bluff body geometrical change to an annular bluff body is inspired by the fact that the areas in which the edge of the bluff body is in contact with the unburned flow have lower temperatures, which can drastically affect combustion parameters, especially emissions. This new geometry is called the Annular Bluff body Stratified Burner, ABSB. The comparison of the mentioned burners is made for three equivalence ratios, Ф, stratification cases: premixed, moderately stratified, and highly stratified with a global equivalence ratio of 0.75, in the conditions of atmospheric pressure and the temperature of the inlet mixture of 26 degrees of Celsius. Flame spectroscopy compares the chemiluminescence intensities of OH*, CH*, C2*, H2O*, and CO2*. Digital image processing, flame edge detection, and exhaust gas analysis are also utilized to measure flames’ general dimensions and emissions. According to experiments, for ABSB cases, a general decrease of about 14% in Nitrogen Oxides, especially NO and NO2, and an increase of about 17% in Carbon Monoxide are observed. Besides, the average bluff body temperature dropped by about 20% in ABSB for all three stratification cases.

Characteristics of NO/SO2 generation during coal/steel dust co-firing under multi-factor synergies

ABSTRACT The co-combustion of solid waste and coal in industrial kilns represents the primary method for the treatment of solid waste. This process must address the critical issue of efficiently controlling nitrogen oxides (NO) and sulfur dioxide (SO2) emissions. In this study, we initially conducted combustion experiments using both single-fuel and mixed-fuel configurations involving coal and steel dust. The experimental results indicated a positive correlation between temperature, airflow rate, and NO/SO2 emissions, while the mixing ratios exhibited a negative correlation. A straightforward regression prediction model for NO/SO2 emissions was developed to enhance understanding of the generation characteristics of NO and SO2, notably, the relative deviation from experimental results was merely 3.16%. This model integrates fuel properties with combustion conditions to elucidate the emission characteristics of nitrogen oxides (NO) and sulfur dioxide (SO2) at their source. Finally, Response surface methodology (RSM) was applied to analyze NO/SO2 emissions under varying operating conditions, including temperature (700–900 °C), air flow rate (80–200 mL/min), and mixing ratios (10–50%).The optimal results were observed at a blending ratio of 50%, where nitrogen (N) and sulfur (S) conversion rates decreased by 25% and 23%, respectively. The results of the analyses determined that the key factors affecting NO emissions, in order of influence, are the mixing ratio, temperature, and air flow rate. For SO2 emissions, the order is mixing ratio, air flow rate, and temperature.

Combustion and emission characteristics of ammonia/methane partially premixed flame under ultrasonic excitation

ABSTRACT Ammonia (NH3) is emerging as a promising alternative fuel due to its high energy density and non-carbon mature. However, its large-scale industrial application is limited by its low reactivity and high nitrogen oxide (NOx) emissions during combustion. This paper investigated the effect of ultrasonic excitation on the combustion and emission characteristics of ammonia-methane-air partially premixed flame in a laboratory-scale burner. The flame temperature distribution was reconstructed using deflection tomography, and the flue gas composition was measured using a multicomponent gas analyzer. Numerical simulations were also conducted under the same experimental conditions. The experimental results showed that applying various ultrasonic frequencies resulted in a stable flame. The ultrasonic excitation resulted in changes in flame brightness and color, as well as a reduction in nitric oxide (NO) emission. Compared to the case without ultrasonic excitation, the maximum flame temperature increased by 17.85%, and NO emission decreased by 19.04% when excited with 20.2 kHz ultrasonic. The simulation results indicated that ultrasonic excitation enhanced the formation of free radicals. Single-point and rate of production (ROP) analysis further revealed that ultrasonic excitation enhanced the dehydrogenation of NHi and the polymerization between NH2 and NH. Additionally, ultrasonic excitation accelerated the direct reactions between NH and N with NO, leading to the formation of N2.

Significant NO2 Formation in Truck Exhaust Plumes and Its Association with Ambient O3: Evidence from Extensive Plume-Chasing Measurements.

Vehicle nitrogen oxides (NOx) significantly increase nitrogen dioxide (NO2) exposure in traffic-related environments. The NO2/NOx ratios are crucial for accurate NO2 modeling and are closely linked to public health concerns. In 2020, we used a mobile platform to follow test trucks (plume-chasing) that were installed with a portable emission measuring system (PEMS) on two restricted driving tracts. Six hundred eighteen exhaust plumes were collected through the PEMS-chasing measurements from seven trucks. The NOx emission factors (EFs), and the NO2/NOx ratios, were calculated at distinct stages (i.e., tailpipe and on-road). A significant reduction in NOx EFs (>64%) was observed with normal operating after-treatment devices, except for trucks equipped with diesel particulate filter (DPF). Disparities in tailpipe NO2/NOx ratios were also found, attributed to the after-treatment technologies. The NO2/NOx ratios measured from plume-chasing were significantly higher (3-4 times, p < 0.001) than the tailpipe measurements, providing field evidence of substantial NO2 formation in exhaust plumes. We developed a quantitative relationship between NO2/NOx ratios from tailpipe and plume-chasing measurements and demonstrated a robust correlation (R2 > 0.90). Since the NO2 formation in the exhaust plume is not explicitly accounted for in NO2 modeling, the quantitative relationship (O3-NO2/NOx) could improve the estimation of NO2 exposure when local emission inventory (tailpipe emissions) is available.

Sources of PM2.5 exposure and health benefits of clean air actions in Shanghai.

Estimating PM2.5 exposure and its health impacts in cities involves large uncertainty due to the limitations of model resolutions. Consequently, attributing the sources of PM2.5-related health impacts at the city level remains challenging. We characterize the health impacts associated with chronic PM2.5 exposure and anthropogenic emissions in Shanghai using a chemical transport model (GEOS-Chem) and its adjoint. By incorporating high-resolution satellited-derived PM2.5 estimates into the calculation, we investigate the response of PM2.5 exposure and its related health impacts in Shanghai to changes in anthropogenic emissions from each individual region, species, sector, and month. We estimate that a 10% decrease in anthropogenic emissions throughout China avoids over 752 (506-1,044) PM2.5-related premature deaths in Shanghai, with changes in local emissions potentially saving 241 (161-334) lives. Ammonia (NH3) emissions are identified as the marginal dominant contributor to the health impacts due to the NH3-limited PM2.5 formation within the city, thus controlling NH3 emissions at both the local and regional scales are effective at reducing the population's exposure to PM2.5. A negative response of the PM2.5 exposure to local nitrogen oxides (NOx) emission changes is detected in winter. Even so, controlling NOx emissions is still justified since the negative impacts decrease as anthropogenic emissions decline and NOx emission reductions benefit the public health on average. The anthropogenic emission changes due to Clean Air Actions helped avoid 3,132 (2,108-4,346) PM2.5-related premature deaths in 2019 relative to 2013, most of which are associated with emission reductions in the agricultural and industrial sectors.

EXAMINING THE ECO-FRIENDLY ASPECTS OF ETHANOL–METHANOL BLENDED GASOLINE ON ENGINE PERFORMANCE AND EMISSIONS

The increasing global demand for energy, environmental concerns, and the limited availability of energy resources have heightened interest in alternative fuels for internal combustion engines. In this context, internal combustion engines like gasoline engines play a significant role in the search for environmentally friendly and sustainable energy sources. Alcohols are among the most used alternative fuels in spark-ignition engines. This study examines the feasibility of using ethanol and methanol alcohols as fuels simultaneously in a gasoline engine. The research investigates the effects of blending 10% ethanol and 10&amp;#37; methanol alternative fuels with gasoline and using the resulting blended fuel as the engine's fuel source on motor performance and exhaust emissions. The study was conducted under throttle wide-open conditions at different engine speeds. The results revealed a maximum decrease of 1.3&amp;#37; in effective power. Significant reductions in hydrocarbon and nitrogen oxide emissions were observed at all engine speeds, with maximum reductions of 18&amp;#37; and 19&amp;#37;, respectively. Furthermore, a decrease in carbon monoxide emissions is evident across the entire spectrum of engine speeds, underscoring the potential of ethanol-methanol blended gasoline to contribute to a reduced carbon footprint in the transportation sector. As a result of the study, in the case of using ethanol and methanol in engines, both the higher oxygen content of alcohols and their high evaporation energy due to their cooling effect cause an improvement in the emission values emitted from the engine without significant deterioration in engine performance parameters.

Synergistic activation of reburned char for ultra-low NOx emissions using flue gas recirculation and natural gas in a 10kW furnace.

The technology of powdered coal injection with recirculating flue gas and natural gas conditioning for reburning represents an advanced and innovative approach to enhancing the efficiency of coal powder reburning. By consuming excess oxygen in the recirculated flue gas, natural gas fosters an environment enriched with reducing agents, which stimulates the reactivity of reburning coal powder and augments its effectiveness in reducing nitrogen oxides (NO). This technology has been comprehensively investigated through experiments conducted in a segmented multi-reactor flow system, simulating conditions akin to those in industrial boilers. To achieve a high level of NO abatement, complete combustion of coal powder, and operational cost-effectiveness, a series of optimal operating parameters has been identified: the temperature in the reburning zone (T1) should be controlled at approximately 1573K; the reburning fuel ratio (Rf) should be maintained around 20%; the excess air coefficient (λfuel) in the reburning zone should be approximately 0.228; the residence time in the reburning zone (t2) should be 0.6s, and the burnout zone residence time (t3) should also be 0.6s; finally, the oxygen concentration in the recirculating flue gas should be regulated to around 10%. This configuration ensures that reactive intermediates such as CO∗, OH∗, H, and CHi generated through natural gas modification enhance the physicochemical structure of coal char, thus amplifying the coal char's capacity for the chemical reduction of NO. Precise control of these parameters is expected to facilitate ultra-low NO emissions, while minimizing the consumption of costly active gases and ensuring the economic efficiency of the system.

Green pickup and delivery problem with private drivers for crowd-shipping distribution considering traffic congestion

Crowd-shipping, employing private drivers to partially replace company-owned trucks in distribution, has emerged as a prominent trend for its cost-effectiveness and sustainability. While crowd-shipping is known as a distribution pattern that combines economic efficiency and environmental benefits, however, the frequent occurrence of traffic congestion has made this pattern less effective than it should be. In this research, the problem of vehicle routing optimization under traffic congestion is investigated from the perspective of simultaneously reducing environmental pollution and costs. Considering private drivers picking up and delivering parcels on the way, this study incorporates the objective of minimizing transport as well as particulate matter (PM) and nitrogen oxides (NOx) emission costs into route optimization for crowd-shipping and proposes a Green Pickup and Delivery Problem with Private Drivers (GPDP-PD). To be more realistic, vehicle speeds depend on the level of traffic congestion, reflecting the time-dependent nature of the proposed model. An improved adaptive large neighborhood search (ALNS) algorithm is developed, and computational experiments are conducted to demonstrate the efficiency of the improved ALNS. Case studies show that there is uncertainty about the environmental benefits of crowd-shipping under traffic congestion. Our proposed model is capable of efficiently allocating private drivers and optimizing vehicle routes according to road conditions, thus identifying the crowd-shipping operational scheme with the lowest cost and emissions. Moreover, a time limit of 0.7-0.8 h and the low cost of private drivers can achieve environmental and economic benefits simultaneously. It provides useful insights into the sustainability of logistics and distribution.

Recent advances in low-temperature nitrogen oxide reduction: effects of electric field application.

This article presents a review of catalytic processes used at low temperatures to reduce emissions of nitrogen oxides (NOx) and nitrous oxide (N2O), which are exceedingly important in terms of their environmental impacts on the Earth. With conventional purification technologies, it has been difficult to remove these compounds under low-temperature conditions. By applying a catalytic process in an electric field for the three reactions of three-way catalysts (TWC), NOx storage reduction catalysts (NSR), and direct decomposition of N2O, we have achieved high catalytic activity even at low temperatures. By promoting ion migration on the catalyst surface, we have filled in the gaps in conventional catalytic technology and have opened the way to more efficient conversion of NOx and N2O.

Ammonia distribution characteristics at the selective catalytic reduction reactor inlet with linear partitioning.

Analyzing the uniformity of ammonia distribution at the inlet of selective catalytic reduction reactors is crucial for enhancing denitrification efficiency. To minimize ammonia slip while ensuring effective denitrification, this study examines ammonia flow characteristics in the SCR system under various zoning schemes. In scheme I, zones A1, A2, A3, and A4 predominantly influence the left, center, center-right, and far-right regions of the reactor inlet. As ammonia velocity increases from 4m/s to 12m/s, the concentration significantly increases, with Zone A4's peak concentration rising from 0.0099 mol/m³ to 0.03 mol/m³. Similarly, increasing the ammonia spraying concentration from 1% to 9% enlarges the affected regions, particularly in Zone A1, where the impacted area expands from 1/3 to 1/2. Scheme II demonstrates a broader and more uniform distribution, which reduces localized concentrations but compromises precision in specific regions. This is of significant importance in reducing nitrogen oxide emissions in coal-fired power plants.