Concentrations Of Nitrogen Oxides Research Articles

A comparative study of two-way and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US: performance evaluation and impacts of chemistry-meteorology feedbacks on air quality.

The two-way coupled Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model has been developed to more realistically represent the atmosphere by accounting for complex chemistry-meteorology feedbacks. In this study, we present a comparative analysis of two-way (with consideration of both aerosol direct and indirect effects) and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US. Long-term (5 years from 2008 to 2012) simulations using WRF-CMAQ with both offline and two-way coupling modes are carried out with anthropogenic emissions based on multiple years of the U.S. National Emission Inventory and chemical initial and boundary conditions derived from an advanced Earth system model (i.e., a modified version of the Community Earth System Model/Community Atmospheric Model). The comprehensive model evaluations show that both two-way WRF-CMAQ and WRF-only simulations perform well for major meteorological variables such as temperature at 2 m, relative humidity at 2 m, wind speed at 10 m, precipitation (except for against the National Climatic Data Center data), and shortwave and longwave radiation. Both two-way and offline CMAQ also show good performance for ozone (O3) and fine particulate matter (PM2.5). Due to the consideration of aerosol direct and indirect effects, two-way WRF-CMAQ shows improved performance over offline coupled WRF and CMAQ in terms of spatiotemporal distributions and statistics, especially for radiation, cloud forcing, O3, sulfate, nitrate, ammonium, elemental carbon, tropospheric O3 residual, and column nitrogen dioxide (NO2). For example, the mean biases have been reduced by more than 10 W m-2 for shortwave radiation and cloud radiative forcing and by more than 2 ppb for max 8 h O3. However, relatively large biases still exist for cloud predictions, some PM2.5 species, and PM10 that warrant follow-up studies to better understand those issues. The impacts of chemistry-meteorological feedbacks are found to play important roles in affecting regional air quality in the US by reducing domain-average concentrations of carbon monoxide (CO), O3, nitrogen oxide (NO x ), volatile organic compounds (VOCs), and PM2.5 by 3.1% (up to 27.8%), 4.2% (up to 16.2%), 6.6% (up to 50.9%), 5.8% (up to 46.6%), and 8.6% (up to 49.1%), respectively, mainly due to reduced radiation, temperature, and wind speed. The overall performance of the two-way coupled WRF-CMAQ model achieved in this work is generally good or satisfactory and the improved performance for two-way coupled WRF-CMAQ should be considered along with other factors in developing future model applications to inform policy making.

Normalizing anthropogenic gas emissions from the combustion of industrial waste as part of fuel slurries

The use of traditional energy carriers results in large amounts of waste, of petroleum origin, in particular. Such waste is highly hazardous when stored in open waste piles or discharged into the soil. It is, therefore, rational to combust it as part of fuel compositions with specialized additives. These additives are utilized to solve specific environmental, energy, social and other tasks. Emission factors were calculated, corresponding to gas emissions, relative to: (i) mass of the fuel to be burned; (ii) maximum/average emissions released into the atmosphere per time; (iii) thermal energy released from combustion; (iv) specific mass emissions of a pollutant per tonne of oil equivalent (toe). The conducted research indicated that the combustion of a slurry derived from oil sludge and water was characterized by the lowest absolute concentrations of carbon, nitrogen and sulfur oxides, which were 7–30%, 9–21% and 41–63% lower, respectively, than those of oil sludge without water. From the considered fuels, the most promising ones by specific normalized factors of SO2 and NO emission were slurries derived from oil sludge and water, but emission factors of CO2 were lower for oil sludge without additives. The information obtained in this study makes it possible to assess the emission characteristics of fuel combustion, taking into account a combination of factors (combustion temperature, fuel mass, etc.), and also makes it possible to compare the results with other studies. Research results show great prospects of using oil sludge as part of composite liquid fuels at power plants.

Global kinetic modeling of low-temperature NH3-SCR for NOx removal using Cu-BEA catalyst

The increasing energy demand and the need to reduce emissions have propelled the use of bioenergy and biofuels. Although carbon emissions can be significantly reduced using biofuels, an increase in the emissions of Nitrogen oxides (NOx) is inevitable. To address this issue, selective catalytic reduction (SCR) using ammonia (NH3) has played a significant role in curbing NOx emissions from the combustion of conventional and biofuels. The combustion usually occurs at low temperature (<350 °C), and hence copper exchanged zeolites have been demonstrated to be an excellent candidate for NOx removal via NH3-SCR. Among the many zeolites, beta (BEA), SSZ-13, and Silicoaluminophosphate (SAPO-34) have shown good SCR activity. To simulate the SCR activity, global kinetic modeling is followed in the literature. In this paper, kinetic modeling is carried out for simulating NH3-SCR using copper-beta (Cu-BEA) catalyst. The model is validated with the experimental data available from the literature. The SCR performance is analyzed for the variations in the feed concentrations of NH3, nitrogen oxide (NO), and oxygen (O2). The model results show that the required ratio of NH3 to NO in the feed is one, and the oxygen concentration above 6% is desired in the feed for excellent SCR activity.

Effects of nighttime heterogeneous reactions on the formation of secondary aerosols and ozone in the Pearl River Delta

<p indent="0mm">Fine particulate matter (PM_2.5) and ozone (O₃) are currently the most concerning air pollutants. Long-term exposure to PM_2.5 and O₃ can induce cardiovascular diseases, presbyopia, and preterm birth. Acute exposure to PM_2.5 and O₃ can also result in hypertension and decreased heart rate variability. In recent years, PM_2.5 pollution abatement in China has achieved remarkable results, but O₃ pollution issues have emerged. In the troposphere, O₃ and PM_2.5 have a close association, i.e., O₃ can oxidize gaseous precursors to form sulfate, nitrate, ammonium and secondary organic aerosols in PM_2.5, and PM_2.5 affects the generation and removal of O₃ by providing surfaces for heterogeneous reactions. Recent studies show that PM_2.5 and O₃ have a significant positive correlation in the photochemically active season in the Pearl River Delta (PRD) region. However, it is still difficult to achieve cooperative control for PM_2.5 and O₃ due to our limited knowledge of their coupling relationship. To date, most studies have focused on the photochemical mechanism in the daytime, and our understanding of the chemical processes at night is insufficient. As an important reactive intermediate, N₂O₅ mainly accumulates through the nocturnal reaction of NO₂ and O₃ and is removed by heterogeneous reactions to produce HNO₃. These processes directly affect ozone production and particulate matter formation. In addition to losing NO_{<italic>x</italic>}, the heterogeneous reaction of N₂O₅ would lead to particulate nitrate formation and photolabile species (i.e., ClNO₂) release. ClNO₂ is a reservoir of NO₂ and chlorine, providing a connection between nitrogen oxide pollution and halogen activation. The formation of ClNO₂ represents an activation process of chlorine from the aerosol phase to the gas phase. ClNO₂ photolysis releases chlorine radicals and oxidizes VOCs, which could increase radical levels and promote ozone formation. Moreover, NO₂ released via ClNO₂ photolysis also promotes O₃ formation in the morning. In coastal areas, sufficient particle chlorine in aerosols might be driven by sea salt chloride interactions, which lead to the formation of ClNO₂. Therefore, with high concentrations of nitrogen oxides, nighttime heterogeneous N₂O₅ reactions would make a substantial contribution to PM_2.5 and O₃ in coastal regions. Although several studies have shown that heterogeneous N₂O₅ reactions play an important role in the formation of PM_2.5 and O₃, related observations in China are limited. In this study, N₂O₅ and ClNO₂ were measured in Shenzhen during the season with severe ozone pollution in October 2018. Iodine chemical ionization time-of-flight mass spectrometry (TOF-CIMS, Aerodyne Inc.) was used to measure N₂O₅ and ClNO₂. Based on collocated measurements of gas- and particle-phase pollutants, we quantitatively calculated the nighttime heterogeneous reactions and assessed their reactivities. The results show that the highest concentrations of N₂O₅ and ClNO₂ could be up to 1524 and 477 pptv <sc>(5 min</sc> average, 1 pptv = <sc>1 pptv=10^–3 mm³/m³)),</sc> respectively, and they were affected by precursors. The concentrations of N₂O₅ and ClNO₂ had pronounced peaks from sunset to sunrise. The nitrate formed via N₂O₅ reactions at night contributed 24%−60% of the total nighttime nitrate particles. In particular, the concentration of ClNO₂ had a noticeable peak in the morning, and the photolysis of ClNO₂ generated Cl radicals, which quickly removed alkanes, and the maximum removal efficiency was 2−3 times higher than that of OH radicals. In addition, the diurnal variation in VOCs with different reactivities also implies that chlorine radicals participate in the VOC oxidation cycle in the morning. This reflects that Cl radical-induced oxidation reactions could promote the generation of ozone and secondary organic aerosols through the HO_{<italic>x</italic>} radical cycle. Our study shows that active nighttime heterogeneous reactions can significantly promote the formation of PM_2.5 and O₃ in the coastal areas of the PRD region. Thus, it is urgent to call for more studies in the future to coordinate the control of PM_2.5 and O₃ in the PRD region.

Diagnosis of ozone formation sensitivity in the Mexico City Metropolitan Area using HCHO/NO2 column ratios from the ozone monitoring instrument

The formation of tropospheric ozone is influenced by emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx), and different regimes of sensitivity to the ozone formation have been identified depending on the concentrations of both groups of compounds. We studied the ozone formation sensitivity in the Mexico City Metropolitan Area (MCMA) using the formaldehyde to nitrogen dioxide ratio (FNR) as a proxy for the VOCs and NOx concentrations, with data retrieved from the Ozone Monitoring Instrument (OMI). To determine the different sensitivity regimes, we compared two previously established threshold values of FNR, which differ from each other in the range of ratios on which the regime transition occurs. The evaluation from 2006 to 2016 showed that the FNR gradually changed, causing variations in the ozone formation sensitivity. While in 2006, more regions were under NOx-limited/transitional regimes, in 2016, the VOC-limited conditions prevailed in most of the city. The analysis disclosed that this change is due to increasing NOx emissions in some regions of MCMA and decreasing VOC emissions in other areas. The observed trend is different from that in major cities in other parts of the world, such as the United States, where ozone formation sensitivity has moved towards NOx-limited conditions. Therefore, reducing VOC emissions would be a suitable approach for decreasing tropospheric ozone concentrations in the MCMA.

Comprehensive Evaluation of Flavor in Charcoal and Electric-Roasted Tamarix Lamb by HS-SPME/GC-MS Combined with Electronic Tongue and Electronic Nose

To prevent the pollution generated during charcoal roasting of tamarix lamb, environmental-friendly electric is gradually applied in meat processing. The profile and formation of flavor in roasted tamarix lamb were evaluated using HS-SPME/GC-MS combined with E-nose/-tongue. Results indicated that charcoal-roasted tamarix lamb exhibited the higher taste of umami and sourness in E-tongue and had higher contents of alcohols, aldehydes, ketones, alkanes, and aromatics in E-nose, while the electric ones exhibited the higher taste of sweetness and bitterness and had higher contents of nitrogen oxides, terpenes, aromatics, and organic sulfur. Compared with charcoal, application of the electric significantly decreased the numbers of key volatile compounds with VIP > 1 (markers) and the contents of most markers.

Finding the Optimal Fatty Acid Composition for Biodiesel Improving the Emissions of a One-Cylinder Diesel Generator

Nitrogen oxides (NOx) and particulate matter (PM) currently are the main pollutants emitted by diesel engines. While there is a start in using hybrid and electric cars, ships will still be fueled by mineral oil products. In the quest to achieve zero-pollution and carbon-free shipping, alternative forms of energy carriers must be found to replace the commonly used mineral oil products. One of the possible alternative fuels is biodiesel. This paper explores the optimization of the composition of biodiesel in order to reduce the concentration of particulate matter and NOx in exhaust gases of a one-cylinder diesel generator.

Numerical simulation of fuel staged swirl combustion in the invert furnace of boiler on advanced ultra-supercritical steam parameters

The paper considers the schemes of Kuznetsky lean coal combustion for the M-shaped boiler. With such a boiler profile, it is possible to significantly reduce the length of main steamlines, which is especially important for the advanced ultra-supercritical parameters of the superheated steam. The furnace in this boiler unit is performed downward (invert). In this work, the aerodynamics of 6 combustion schemes was simulated by means of computational fluid dynamics. All considered schemes were designed on the basis of direct-flow burners and nozzles. For the most aerodynamically reasonable scheme the thermal processes in the boiler furnace firing Kuznetsky lean coal have been simulated by means of computational hydrodynamics. The simulation results showed a high efficiency of fuel burnout: loss due to unburned combustible equaled 0.1%, carbon-in-ash loss equaled 0.8%. Carbon monoxide concentration at the furnace outlet in conversion to excess air equal α = 1.4 amounted 226 mg/m3, the nitrogen oxides concentration in the flue gases (in conversion to normal conditions) equaled 424 mg/m3. It is appropriate to use the results obtained in this research in the development of new solid fuels combustion schemes.

Влияние регулируемых параметров рабочего процесса на образование оксидов азота в водородном дизеле

The article considers formation of nitrogen oxides in a hydrogen diesel engine with direct injection of gaseous hydrogen depending on the adjustable parameters of the working process: excess air ratio, cyclic hydrogen supply, advance angle and duration of hydrogen injection. It was found that in a number of cases the effect of these parameters on the working process and the emission of nitrogen oxides leads to results that differ significantly from those in traditional diesel engines running on hydrocarbon fuel. It is shown that by varying the specified controlled parameters, it is possible to minimize the concentration of nitrogen oxides in the exhaust gases of a hydrogen diesel engine.

ZONING OF THE CITY TERRITORY BY THE LEVEL OF ATMOSPHERIC AIR POLLUTION BY NITROGEN OXIDES

The problem of building an ecologically clean city is considered, taking into account the basic principles of its construction, maintenance, zoning of ecological functions and, at the same time, the need to maintain sustainable development. Calculations of the concentration of emissions of nitrogen oxides in fourteen transport nodes - intersections of the main roads of the city were carried out, the dispersion of the distribution of impurities in the atmosphere was determined.&#x0D; On the basis of the criterion of the traffic intensity of vehicles, the zoning of the territory around the intersections of the main roads of the city was proposed according to the level of atmospheric air pollution with nitrogen oxides: safe zones, where the content of nitrogen oxides is less than the average daily maximum permissible concentrations (maximum allowable concentration = 0.04 mg/m3); zones of low safety, where the content of nitrogen oxides is less than the maximum one-time maximum permissible concentration (maximum allowable concentration = 0.4 mg/m3); hazardous zones, where the level is higher than the maximum allowable concentration, constant monitoring and special treatment facilities are needed.&#x0D; The calculation of the traffic intensity of vehicles, which is necessary to achieve the maximum allowable rate for nitrogen oxide emissions, and the ratio between the substances. Sanitary protection zones-territories around the main hubs, where nitrogen oxides have a harmful effect on the environment and human health, have been calculated. It was revealed that the predominant north-western direction of winds leads to an increase in the territory of pollution up to 850 m, if the highway has eight lanes. A conceptual model of the transition to clean air in urbanized areas is proposed, according to which, in fact, it is necessary to solve the problems of coexistence and protection:&#x0D; - a person who seeks to live comfortably, and comfort requires constant progress and at the same time preserving his health;&#x0D; - transport, which is associated with the need to quickly move goods and services, requires sustainable economic development and leads to climate change;&#x0D; - the environment, the state of which under anthropogenic influence is deteriorating against the background of intensification of natural disasters.

MODEL OF NITROGEN OXIDE POLLUTION OF THE CITY MAINS

To manage the quality of atmospheric air in the city, it is of great importance to study the formation of extremely high atmospheric pollution. The preliminary assessment of atmospheric air pollution allows to determine the contribution of road transport emission sources, with the help of which it is possible to simulate a specific situation and to give predictive assessments of the state of atmospheric air pollution,&#x0D; as well as to determine the ways to improve the environmental characteristics of road transport, develop the city road network and other factors. The transport model of the city is one of the tools for strategic transport planning that allows for the justification and adoption of effective and responsible design decisions in the field of transport and infrastructure.&#x0D; The following data analysis on the available sources of atmospheric air pollution of the city mains has been performed: an assessment of the road transport intensity, an assessment of the amount of nitrogen oxides emissions, an assessment of the level of nitrogen oxides in the atmospheric air. Measurements have shown that the average concentrations of nitrogen oxides in places of intense anthropogenic load –the crossroads of city mains – are dozens of times higher than the maximum permissible concentration. Nearby the city mains and crossroads, the maximum concentrations of pollutants are formed at low wind speeds with wind directions at an angle close to 45° to the main areas.&#x0D; On the basis of the calculations, the following model of nitrogen oxide pollution of the city mains was obtained – the dependence of the concentration of nitrogen oxides on the road transport intensity can be a criterion for zoning the city territory according to the degree of atmospheric air pollution.

Analysis of Two-Stage Fuel Combustion in Multi-Fuel Boilers

The significant growth of industry in the second half of the 20th century led to a number of problems, one of the most important problems is the protection of the environment from pollution. The main source of air pollution is heat and power generating plants, which are based on combustion processes. The largest pollutant is thermal power plants, which burn a large volume of fossil fuel and form a corresponding amount of toxic substances, in particular nitrogen and sulfur oxides. In this paper, combustion processes with various burner devices will be considered and two fuels – natural gas, fuel oil. One of the most important tasks operation of power equipment is the development and widespread use of effective methods to reduce the formation of harmful substances and determining the optimal modes of fuel combustion, ensuring a minimum level of emissions of toxic combustion products. Two-stage fuel combustion is an effective method of reducing nitrogen oxide emissions. In two-stage combustion, one fuel burnout zone is replaced by several zones, as isolated as possible. The paper will compare several options for the implementation of two-stage combustion in the boiler. The influence of boiler load on the concentration of nitrogen oxides in the exhaust gases is analyzed. Also at two-stage combustion of fuel oil in gas-oil boilers reliability of screen surfaces of heating as a result of decrease in the maximum falling heat streams on a screen surface of heating of a copper increased.

Characteristics of PM and PAHs emitted from a coal-fired boiler and the efficiencies of its air pollution control devices

ABSTRACT Sampling and analysis of filterable particulate matter (FPM), FPM2.5, condensable particulate matter (CPM), polycyclic aromatic hydrocarbons (PAHs), sulfur oxides (SOx) and nitrogen oxides (NOx) emitted from a coal-fired boiler equipped with selective catalytic reduction (SCR)+ electrostatic precipitator (ESP) + wet flue gas desulfurization (WFGD) + wet electrostatic precipitator (WESP) as air pollution control devices (APCDs) are conducted. The results show that NOx concentration emitted from the coal-fired boiler is 56 ± 2.17 ppm (with the NOx removal efficiency of 47.2%), which does not meet the best available control technology (BACT) emission standard (≤ 30 ppm). On the other hand, the WFGD adopted has a good removal efficiency for SOx and HCl. Both SOx and HCl emission concentrations are <1 ppm, and removal efficiencies are >99%. The FPM and FPM2.5 emitted from the coal-fired boiler are 0.9 ± 0.06 mg/Nm3 and <0.09 ± 0.006 mg/Nm3, respectively. The overall removal efficiency of FPM achieved with ESP+WFGD+WESP+MGGH is 99.98%. However, high concentration of CPM (37.4 ± 6.3 mg/Nm3) is measured, which is significantly higher than FPM and FPM2.5. The concentrations of 27 PAHs at the WESP inlet and stack are measured as 667 ng/Nm3 and 547 ng/Nm3, respectively while the removal efficiencies of gas- and solid-phase PAHs are 9% and 58%, respectively. The results show that APCDs adopted are not effective in removing PAHs (only 18%), and gas-phase PAHs contribute the most in the total PAH emission. In addition, the benzo(a)pyrene equivalent (BaPeq) concentration emitted from the stack is 28.8 ng-BaPeq/Nm3, and most of it is contributed by 4-6 ring PAHs with high toxic equivalent factors (TEFs). Furthermore, the emission factors of air pollutant emitted from coal-fired boilers equipped with different combinations of APCDs are compiled and compared. The results show that except for CPM and NOx, the emission factors of air pollutant calculated for this coal-fired boiler are lower if compared with other studies.

Динамика сывороточных уровней метаболитов оксида азота и сульфида водорода как маркеров развития органной дисфункции в остром периоде политравмы

Актуальность. У пациентов с сочетанными травмами отмечается высокий уровне риска развития шока, осложнений и смерти. В наше время существуют системы оценки, которые позволяют установить степень тяжести политравмы и определяют прогноз заболевания, но их чувствительность значительно ограничена тем, что они являються субъективными. В последние годы большое внимание уделяется газовым трансмиттерам, к которым относятся оксид азота (NO), монооксид углерода (СО) и сульфид водорода (H2S). Поскольку производство газовых трансмиттеров многими типами клеток повышается при повреждении ткани, допускают, что их концентрация, а также концентрация продуктов их окисления в сыворотке крови представляют собой маркер политравмы, коррелирующий с прогнозом. Цель: определить степень нарушения эндотелиальной дисфункции и патогенетическую роль газотрансмиттеров как маркеров развития органной дисфункции в остром периоде политравмы. Материалы и методы. В работе приведены данные клинического обследования и лечения 28 больных с политравмой. Средний возраст пострадавших — 48,4 ± 5,2 года. В зависимости от тяжести пациентов при поступлении проведена стратификации по шкале APACHE II: 1-я группа (n = 22) — среднетяжелая политравма; 2-я группа (n = 6) — тяжелая поли­травма. Результаты. Происходило значительное уменьшение уровня нитроксида уже при госпитализации у пациентов 1-й и 2-й групп по сравнению с нормой — 0,49 ± 0,06 мкмоль/л, р = 0,001. Спустя сутки интенсивной терапии у пациентов обеих групп уровень NO крови возрастал до 0,43 ± 0,03 мкмоль/л и 0,45 ± 0,03 мкмоль/л соотвественно. При поступлении у пациентов межгрупповые отличия среднего уровня NOx крови были достоверными (р = 0,003). После проведения интенсивной терапии у пациентов обеих групп уровень NO2 + NO3 продолжал увеличиваться (р = 0,001 по сравнению с предыдущим этапом, а между группами статистически значимых отличий не было (р = 0,475). Средний уровень H2S в крови при поступлении пациентов 1-й и 2-й групп был достоверно выше нормы (р = 0,025). Отличия между группами были недостоверными (р = 0,117). Проведение интенсивной терапии сопровождалось норма­лизацией уровня H2S. Выводы. У больных с политравмой в остром периоде наблюдается развитие эндотелиальной ­дисфункции, которая подтверждается статистически значимыми изменениями уровня газо­трансмиттеров в сыворотке крови. Концентрации NO и продуктов его окисления (NOx) в сыворотке крови, определенные при госпитализации, являются чувствительными маркерами тяжести политравмы. Низкий уровень NOx у больных с крайне тяжелой травмой при госпитализации может прогнозировать не­благоприятный исход острого периода травматической болезни.

Using Plasma Activation to Optimize the Combustion Process and Minimize Harmful Emissions

AbstractThe possibility of introducing plasma ignition of fuel in combustion chambers of power boilers was investigated by using 3D computer modeling methods. Computational experiments were carried out on operating boilers, and a comparison of the characteristics of the combustion process for traditional fuel combustion and its thermochemical variant was carried out. Plasma technology allows the concentration of carbon and nitrogen oxides at the outlet of the furnace to be reduced. The results obtained showed the efficiency of thermochemical plasma activation of fuel and the possibility of its application in real heat and power facilities to optimize combustion processes and minimize harmful emissions.

Effect of the RME Biodiesel on the Diesel Engine Fuel Consumption and Emission

Road transport is the primary source of atmospheric air pollution, thus posing a threat to human health and life. The aim of the study was to determine the impact of fuel obtained from plants on the ecological properties of a compression ignition engine. The article reports the results of investigations into a modern engine with a Common Rail system, powered by the RME (rapeseed methyl esters) biodiesel and their blends with diesel. For comparison, the engine was also fuelled with conventional diesel oil without ester addition. When powering the engine with blends and pure biodiesel, brake specific fuel consumption increased. The concentrations of nitrogen oxides and carbon dioxide in the engine exhaust gas also slightly increased. At the same time, a clear reduction in average concentrations of carbon monoxide, hydrocarbons and particulates matter was obtained.

Rancang Bangun Alat Pendeteksi NOx dan CO Berbasis Mikrokontroler ESP32 dengan Notifikasi Via Telegram dan Suara

The design of NOx and CO detectors based on notifications via telegram and voice has been carried out. This detector consists of a gas sensor MQ-135 as a nitrogen oxide detector and an MQ-7 sensor as a carbon monoxide detector. Data processing is carried out using an ESP32 microcontroller which can send results to a telegram bot and play sound using speakers connected to the ISD 1820 sound module. The tool made can send notifications if the concentration of nitrogen oxides and carbon monoxide exceeds 50 ppm. The test is carried out by burning waste to produce smoke. Burning smoke contains various gases and particles that are harmful to the body. The characterization of the MQ-135 sensor was carried out by comparing the data obtained from the ISPU to measure nitrogen oxide gas and producing an error value of 9.09%. Meanwhile, the characterization of the MQ-7 sensor was carried out using a biogas analyzer and resulted in an error ratio of 3.26%. These results prove that the tools that have been designed can work well.

Effect and mechanism of combustion enhancement and emission reduction for non-premixed pure ammonia combustion based on fuel preheating

Ammonia (NH3) is a hydrogen-rich carrier with high energy density and is a carbon-free energy source. NH3 is a new carbon-free alternative fuel with great attraction and prospect. NH3 is restricted to large-scale industrial application because of its low reactivity and high nitrogen oxide (NOx) emissions in combustion. This research evaluated non-premixed pure NH3 combustion enhancement method and emission law based on fuel preheating. An NH3 preheating device, non-premixed burner, flue gas analysis, and temperature measurement system were designed and constructed. Combustion characteristics of NH3 preheating were investigated under different preheating temperatures and NH3 flow rates. NH3 flame images were captured by a CCD camera. The temperature distributions of the NH3 flames were reconstructed by deflection tomography technology. In addition, the composition concentrations of flue gas were obtained by a multi-component gas analyzer. The influence of preheating temperature on flame characteristics, combustion temperature field, and pollutant emission were analyzed. A numerical simulation was performed under the same experimental conditions. The effects of NH3 preheating on flame and emission characteristics were analyzed by sensitivity analysis and reaction path analysis. The mechanisms of the combustion enhancement and emission reduction for preheating NH3 non-premixed combustion were explained. Results showed that stable non-premixed pure NH3 flame was generated at different experimental flow rates when the NH3 preheating temperature was higher than 593 K. The brightness, color, and structure of the flame varied significantly with increasing preheating temperature. Furthermore, the concentration of NOx decreased obviously, and the concentration of unburned NH3 was extremely low. The chemical reaction rate was tremendously promoted with increasing preheating temperature, and the reaction pathway of N radical was extremely related to nitric oxide (NO) production and consumption.

Assessment of noise and ozone levels in a small industrial urban area

Monitoring environmental parameters in urban centers has become a critical step for health risk assessment. In this study, conducted in the industrial park of Mirandela (Portugal), an environmental monitoring system consisting of a meteorological station, a class 1 smart sound sensor and three reference optical gas analyzers were deployed to measure noise levels, tropospheric ozone concentrations, carbon monoxide, and nitrogen oxides, during winter and spring of 2019. The interdependence among all variables was evaluated, and legal compliance was assessed according to the European Union (EU) target values for ozone. Higher concentrations of nitrogen oxides and carbon monoxide were observed during rush hours, while ozone concentrations increased as a consequence of the emissions of primary pollutants after sunrise reaching their maximum values at about 13:00 to 14:00h. Regarding the Accumulated Ozone Exposure (AOT), both target values set by the EU for AOT40 vegetation and forest have been exceeded. For AOT60, the observed values were below target; however, the threshold for NET60 was exceeded even before the end of 2019. Noise levels were higher during rush hours, because of higher traffic intensity; however, noise level indicators (Lden, Ln) remained within the legal limits. It was possible to realize that urban traffic is the most relevant source of noise and local air pollution. These results can be used to define strategies that may improve the environmental performance of the studied industrial park.

Assessing the intra-urban variability of nitrogen oxides and ozone across a highly heterogeneous urban area.

High-resolution air quality maps are critical towards assessing and understanding exposures to elevated air pollution in dense urban areas. However, these surfaces are rarely available in low- and middle-income countries that suffer from some of the highest air pollution levels worldwide. In this study, we make use of land use regressions (LURs) to generate annual and seasonal, high-resolution nitrogen dioxide (NO2), nitrogen oxides (NOx), and ozone (O3) exposure surfaces for the Greater Beirut Area (GBA) in Lebanon. NO2, NOx and O3 concentrations were monitored using passive samplers that were deployed at 55 pre-defined monitoring locations. The average annual concentrations of NO2, NOx, and O3 across the GBA were 36.0, 89.7, and 26.9ppb, respectively. Overall, the performance of the generated models was appropriate, with low biases, high model robustness, and acceptable R2 values that ranged between 0.66 and 0.73 for NO2, 0.56 and 0.60 for NOx, and 0.54 and 0.65 for O3. Traffic-related emissions as well as the operation of a fossil-fuel power plant were found to be the main contributors to the measured NO2 and NOx levels in the GBA, whereas they acted as sinks for O3 concentrations. No seasonally significant differences were found for the NO2 and NOx pollution surfaces; as their seasonal and annual models were largely similar (Pearson's r > 0.85 for both pollutants). On the other hand, seasonal O3 pollution surfaces were significantly different. The model results showed that around 99% of the population of the GBA were exposed to NO2 levels that exceeded the World Health Organization defined annual standard.