NOx Values Research Articles

Throttling Effect on the Performance and Emissions of a Multi-Cylinder Gasoline Fuelled Spark Ignition Engine

The throttle mechanism, a regulatory technique of engine output, is accompanied by a loss of some energy. The effect of intake air throttling on the performance and emissions of a multi-cylinder spark ignition gasoline engine was experimentally investigated. The engine was coupled to a hydraulic dynamometer equipped with a customized cooling system for both the engine and dynamometer. Experimental tests were performed for various engine speeds and air-fuel ratios at the WOT and POT conditions with optimized ignition timing. The acquired results recorded that a better engine operation could be achieved with WOT in terms of bmep, bsfc, ηb, CO, CO2 and UHC compared to POT. At the same time, the worst trend at WOT was noticed for the NOx concentration due to the higher conversion efficiency of fuel combustion. In terms of engine speed for both WOT and POT conditions, operating at 3000 rpm represents the minima of ϕ, bsfc, CO and UHC; and the maxima of ηb, CO2 and NOx with some fluctuation on both sides of this point. Maximum recorded values of ηb were about 30.55% and 28. 55%, while the minimum values of bsfc were about 274 and 293 g/kW.h for the WOT and POT conditions, respectively. The maximum bmep was obtained at 2500 rpm at WOT and POT conditions with values of about 940 kPa and 904 kPa, respectively. Maximum recorded values of NOx were about 1525 and 977 ppm for the WOT and POT conditions, respectively.

An Artificial Intelligence Regression Model for Prediction of NOx Emission from Flame Image

In this study, NOx emission has been estimated by processing the flame image of visible wavelength and its experimental verification has been presented. The experimental study has been performed by using a domestic coal boiler with a capacity of 85000 Kcal / h. The real NOx value has been measured from a flue gas analyzer device. The flame image has been taken by CCD camera from the observation hole on the side of the burner. The data set which is related to instantaneous combustion performance and flame images was recorded simultaneously on the same computer with time stamps once a second. The color flame image has been transformed into a gray scale. Features have been extracted from the gray image of flame. The features are extracted by using the cumulative projection vectors of row and column matrices. ANN regression model has been used as the learning model. The relationship between flame image and NOx emission has been obtained with the accuracy of R = 0.9522. Highly accurate measurement results show that the proposed NOx prediction model can be used in combustion monitor and control systems.

A novel robust dynamic method for NOx emissions prediction in a thermal power plant

AbstractNOx is a harmful by‐product of coal‐fired boilers, and accurate prediction of NOx emissions in the outlet of a boiler is essential for environmental protection. In recent years, data‐driven models have been widely studied and applied in this area. However, dynamic characteristics are ignored by many existing models, leading to sub‐optimal performance. Besides, outliers that occur in the operation data have adverse effects on the efficacy of these prediction models. To address these issues, this paper presents a novel method for predicting NOx concentration via integrating a robust dynamic probabilistic approach and the long short‐term memory (LSTM). First, mutual information (MI) is applied to determine the input variables. Subsequently, a robust probabilistic method is proposed to extract dynamic latent features considering outliers. On this basis, the generated latent variables are further utilized to train the LSTM‐based model, with which the intrinsic relation between inputs and NOx values are obtained. Based on the application to a 660 MW thermal power plant, the superiority of the proposed method is demonstrated in terms of high prediction accuracy.

Review of Air Intake System Development for Internal Combustion Engine

Today air intake system for internal combustion engines has experience changes to increase its performance. In existence of an appropriate air supply will affect the air-fuel ratio (AFR) and impact on the power generated and decrease the value of NOx for more complex effects. The increasing demand for energy encourages the creation of new technologies that increase the value of work in the form of decreasing emissions, increasing efficiency to longer durability. The method used in this study is a comparison of the results of each starting air system. The air intake system functions as an air supply for the combustion process, the first air intake system utilizing atmospheric pressure to push air into the combustion chamber which today has developed with a turbo system. Turbo system has functions to increase the amount of air supply and compress it, so that the combustion process will be more efficient and produce more environmentally friendly exhaust gases and more optimal power, in other words better efficiency this is known as a turbocharger.

Experimental Investigation of the Effect of Nitromethane Addition to Gasoline Fuel on A Single-Cylinder Spark-Ignition Engine Performance and Emissions

In this study, the effect of nitromethane addition to gasoline fuel on engine perfor-mance and emissions in a single-cylinder spark-ignition engine was experimentally inves-tigated. By adding 5% and 10% nitromethane to gasoline, experiments were carried out at full load at six different cycles. Engine load, fuel consumption, exhaust gas tempera-ture, and emissions were measured during the experiments. According to the measured experimental data, engine power, torque, specific fuel consumption, exhaust gas tem-perature, average effective pressure, thermal efficiency, CO, CO2, HC, and NOx values were compared with each other. According to these results, nitromethane's addition im-proved engine power, torque, specific fuel consumption, and thermal efficiency. It is un-derstood that the addition of nitromethane to gasoline improves combustion efficiency and increases thermal efficiency. With the addition of nitromethane, an increase in CO2 emission, which is a product of complete combustion, and a decrease in CO emission occurred. This supports the increase in combustion efficiency. HC emissions have de-creased. There has been an increase in NOx emissionsIn addition, since the addition of more than 10% nitromethane causes engine instability, it has created difficulties in using it without modification in the engine.

ANALYSIS OF FORMATION THE GREENHOUSE EFFLUENTS TO ATMOSPHERE AND NITROGEN OXIDES PRODUCTION BY COMBUSTION THE METHANE-HYDROGEN MIXTURES

Within the framework of decarbonization of environment, the processes of the greenhouse gases formation in atmosphere by combustion the gas fuels (generally) and the natural gas substitution (particularly) the conditions of reducing the CO2 emission by methane-hydrogen mixtures burning are considered. The data on nitrogen oxides’ effluents are generalized in the work as well.
 An important role of non-isothermal state and of radiation selectivity of three-atomic gases CO2 and H2O for the resulting heat exchange and by evaluation the corresponding heat fluxes has been stated. The data are discussed basing upon the calculations’ results of the radiative heat transfer within the layer of combustion products (CP) of natural gas for the case of non-isothermal emitting layer at partial pressures pH2O : pCO2 = 2 : 1.
 The conclusion has been accepted on limitations regarding the opportunities to reduce the CO2 emission for the case of premixed methane-hydrogen mixtures burning while fuel combustion with an air-oxidant is proceeded. The evaluation under consideration has been proven taking into account only the cases of minor shares of [H2] ≤ 20–30 % (vol.) in fuel used by proper conditions for the domestic gas devices. The expected reduction of [CO2] mass emission fraction under combustion is reduced only by 10 % compared with the natural gas (methane) burning.
 It has been found for the first time that in case of the fuels, not containing the nitrogen, the equilibrium concentrations of two main nitrogen oxides NO and NO2 have practically the same (invariable) NOx values (by each of oxides), independently on fuel composition: methane and higher hydrocarbons, methane-hydrogen gas mixtures at any fixed given temperature (T = idem) and definite air-oxidant’s excess factor (λ = idem).
 This supposition has been numerically grounded and analyzed for the conditions of combustion the mentioned gas fuels under both the cases: of dry or wet air-oxidant. Bibl. 26, Fig. 4, Tab. 3.

Downscaling global anthropogenic emissions for high-resolution urban air quality studies

This study presents a method for “downscaling” aggregated global emissions of CO, NOx, and PM2.5 based on georeferenced information (spatial proxies). We distribute ECLIPSE-CLE emissions for Quito, Ecuador, in 2015 and 2017. The study area is a grid of 0.5 × 0.5 km2 cells over a 110 × 110 km2 area. The emission sectors (proxies in parenthesis) are agricultural (land-use maps), domestic (land-use and population density), energy, industry, and waste disposal (point source location from local inventory), and transport (population, vehicle traffic, and road density). Emission distribution quality is satisfactorily evaluated (graphically and statistically) by implementing them in the UBM model and comparing modeled concentrations with observations. This study also explores an alternative proxy set-up for main road emissions based on road density, which, for some modeling sites, results in a better agreement with the observations. Finally, this methodology is applied for comparing air pollution due to two urban growth types for Quito in 2040: sprawl and densification. Both scenarios lead to lower concentrations than in 2017, except for O3. Although the two scenarios attain similar concentrations, urban sprawl presents, in general, noticeably higher values for NOx and NO2.

Effect of air staging on NOx emissions in biomass combustion in a bubbling fluidized bed

NOx emissions belong to the most critical gaseous emissions in thermal conversion of biomass and non-recyclable waste. Yet the role of air staging on NOx reduction is not fully understood in most combustion systems. This study investigates the effect of air staging on the NOx reduction in an industrial bubbling fluidized bed by means of a detailed kinetic mechanism and assuming gradual entrainment of flue gases (with NOx precursors) into the air jets. The computed data is compared to unique non-published experimental industrial-scale data, from a 107 MWth biomass-fired fluidized bed boiler. The air was staged via primary air (through the bed), and secondary and tertiary air jets with a high inlet velocity. NO, HCN and NH3 concentrations were measured inside the furnace at a depth of 1.8 m, below the secondary air jets, above the secondary air jets and above the tertiary air jets. The computed NOx values were in good agreement with the experimental values. Above the bed, the total NO + HCN + NH3 concentration was 1169 ppm. After the tertiary air staging the total NO + HCN + NH3 concentration was 76 ppm. The conversion of fixed nitrogen (NO + HCN + NH3) to N2 reached 65 % after the secondary air jets, and 90 % after the tertiary air jets. The study shows that exceptional reduction of NOx emissions can be achieved with air staging in this type of industrial combustion systems for biomass.

A Numerical Study of Decarbonizing Marine Gas Turbine Emissions Through Ammonia/Hydrogen Fuel Blends

The employment of gas turbine in combination with diesel engines and steam generators is a well-known power generation technique in modern marines and ship propulsion. Previously, it rendered its foundations in marine industry through higher power weight ratios and lower NOx emissions if compared to pure diesel engine driven marines. As climate change concerns are becoming more serious, the decarbonization of marine combustion products is becoming of environmental concern. In the present study a modified design of the burner and combustor was suggested to allow for the longer residence time required for releasing the combustion products from the ‘slow’ burning ammonia molecule. Afterwards, the more formidable challenge of relatively higher NOx emissions was treated through analysis of the effect of altering the equivalence ratio, hydrogen blending, increasing the combustor working pressure and staging the combustion. The latest tactic resulted in lowering values of exit NOx to around 30 ppmv, which is a quite promising result.

Performance and emission evaluation of a marine diesel engine fueled with natural gas ignited by biodiesel-diesel blended fuel

In this paper, a marine dual fuel diesel engine fueled with the natural gas (NG: 60%, 70% and 80%) ignited by the biodiesel-diesel blended fuel (25%, 50% and 75% biodiesel by volume) was studied under different conditions. Based on the experiment, a computational fluid dynamics (CFD) model was established, and an improved chemical kinetic mechanism was developed to simulate the fuel spray process and combustion process. The ignition, combustion and emission characteristics of diesel engine fueled with different blended fuels were investigated under different load conditions. In addition, the temperature sensitivity of methane mole fraction with different NG energy fractions was analyzed at the 800 K and 1000 K. The results showed that the additions of NG and biodiesel in the blended fuel had a significant effect on the combustion and emission characteristics of the diesel engine. The starting of combustion (SOC) of the dual fuel engine lagged with the increases of NG and biodiesel content. The maximum enhancement of SOC reached 0.72°CA. The biggest influence on temperature was R122, which was the main reason for the shorter ignition delay during the combustion process. In all cases, NOx, CO and soot emissions decreased with increasing NG energy fraction. The maximum values of NOx, CO and soot emissions reached 1590 ppm, 461 ppm and 1.42 E−07 kg. Considering the combustion and emission characteristics of the engine, the best fuel blending ratio was EF80-B25.

Effect of n-butanol on cotton seed oil biodiesel: an approach for improving the emission behavior of DI diesel engine

The broad applications of IC engines hasten the evolution of our civilization and society. In this research, the biodiesel is derived from cottonseed oil through trans-esterification process and various diesel blends with fuel additive (n-butanol) were prepared and tested in single cylinder and four stroke diesel engine. The results for blend B20 showed 11% higher SFC than diesel. Use of BN20 as a fuel helped a decrease by 3.45% with B20. There was a 5.58% rise in the BTE of BN20 compared to B20 at medium operating conditions. Carbon monoxide (CO) emission of B20 was 33% lower than diesel and BN20 blend 16.7% lower than B20. A hydrocarbon (HC) emission from pure biodiesel (B100) resulted in a 10.5% reduction compared to diesel while the increase with respect to BN20 was 13.6%. The NOx emission for B20 and B100 were 7.4% and 16% increases compared to diesel respectively. The NOx value decreases with addition of n- butanol to B20 was 2.4% compared to B20. It was observed that the CSOME with n-butanol a good choice of fuel in terms of performance and improved emissions than diesel and would be a better substitute fuel for a diesel engine.

Concentrations of nitrogen compounds are related to severe rhinovirus infection in infants. A time-series analysis from the reference area of a pediatric university hospital in Barcelona.

BackgroundThere is scarce information focused on the effect of weather conditions and air pollution on specific acute viral respiratory infections, such as rhinovirus (RV), with a wide clinical spectrum of severity.ObjectiveThe aim of this study was to analyze the association between episodes of severe respiratory tract infection by RV and air pollutant concentrations (NO x and SO2) in the reference area of a pediatric university hospital.MethodsAn analysis of temporal series of daily values of NO x and SO2, weather variables, circulating pollen and mold spores, and daily number of admissions in the pediatric intensive care unit (PICU) with severe respiratory RV infection (RVi) in children between 6 months and 18 years was performed. Lagged variables for 0–5 days were considered. The study spanned from 2010 to 2018. Patients with comorbidities were excluded.ResultsOne hundred and fifty patients were admitted to the PICU. Median age was 19 months old (interquartile range [IQR]: 11–47). No relationship between RV‐PICU admissions and temperature, relative humidity, cumulative rainfall, or wind speed was found. Several logistic regression models with one pollutant and two pollutants were constructed but the best model was that which included average daily NO x concentrations. Average daily NO x concentrations were related with the presence of PICU admissions 3 days later (odds ratio per IQR‐unit increase: 1.64, 95% confidence interval: 1.20–2.25)).ConclusionsThis study has shown a positive correlation between NO x concentrations at Lag 3 and children's PICU admissions with severe RV respiratory infection. Air pollutant data should be taken into consideration when we try to understand the severity of RVis.

Effects of hydrocarbon liquid and HHO as the alternate fuel for unmodified compression ignition engines

In recent days dual blends displays excellent activity in the reduction of the formation of the greenhouse gases during combustion. The current study predicted the effects of the HHO on the conventional diesel engine without any major modifications to the engine. The blends K-1 type kerosene were added to the waste cooking biodiesel at the two different fashions (5% and 10%). To observe the effects of biodiesel, kerosene and hydrogen, this study encompasses performance and emission characteristics at different engine loading conditions (0% to 90%). The oxyhydrogen generated from the portable system were injected in to the diesel engine as the part of co-flow. Based on the BTE, BSFC, HC, CO, NOx and CO2 values, the introduction of the hydrogen was the promising option in the area of alternate fuel. However, addition of the hydrogen to the biodiesel affects the ignition delay owing to the premature combustion. Further, compared to the neat diesel, addition of hydrogen with the convention fuel reported decent brake thermal efficiency and the reduced formation of carbon footprints in the emissions. The maximum BTE has been reported by B20 + HHO + K10 blend of 38% and their respective BSFC and EGT was 228 g/kWh and 200 °C. Similar to above, the emission values of CO and CO2 were lower than neat diesel. On the contrary, there is no evidence of reduction on NOx formation.

Assessing the roles emission sources and atmospheric processes play in simulating <i>δ</i><sup>15</sup>N of atmospheric NO<sub><i>x</i></sub> and NO<sub>3</sub><sup>−</sup> using CMAQ (version 5.2.1) and SMOKE (version 4.6)

Abstract. Nitrogen oxides (NOx= nitric oxide (NO) + nitrogen dioxide (NO2)) are important trace gases that affect atmospheric chemistry, air quality, and climate. Contemporary development of NOx emissions inventories is limited by the understanding of the roles of vegetation (net NOx source or net sink), vehicle emissions from gasoline- and diesel-powered vehicles, the application of NOx emission control technologies, and accurate verification techniques. The nitrogen stable isotope composition (δ15N) of NOx is an effective tool to evaluate the accuracy of the NOx emission inventories, which are based on different assumptions. In this study, we traced the changes in δ15N values of NOx along the “journey” of atmospheric NOx, driven by atmospheric processes after different sources emit NOx into the atmosphere. The 15N was incorporated into the emission input dataset, generated from the US EPA trace gas emission model SMOKE (Sparse Matrix Operator Kernel Emissions). Then the 15N-incorporated emission input dataset was used to run the CMAQ (Community Multiscale Air Quality) modeling system. By enhancing NOx deposition, we simulated the expected δ15N of NO3-, assuming no isotope fractionation during chemical conversion or deposition. The simulated spatiotemporal patterns in NOx isotopic composition for both SMOKE outputs (simulations under the “emission only” scenario) and CMAQ outputs (simulations under the “emission + transport + enhanced NOx loss” scenario) were compared with corresponding measurements in West Lafayette, Indiana, USA. The simulations under the emission + transport + enhanced NOx loss scenario were also compared to δ15N of NO3- at NADP (National Atmospheric Deposition Program) sites. The results indicate the potential underestimation of emissions from soil, livestock waste, off-road vehicles, and natural-gas power plants and the potential overestimation of emissions from on-road vehicles and coal-fired power plants, if only considering the difference in NOx isotopic composition for different emission sources. After considering the mixing, dispersion, transport, and deposition of NOx emission from different sources, the estimation of atmospheric δ15N(NOx) shows better agreement (by ∼ 3 ‰) with observations.

Assessment of Diesel Engine Performance, Combustion and Emission Characteristics with Supplementation of Neem Oil Methyl Ester Along With EGR

Biodiesel generated from a variety of non-edible feedstocks has gained widespread acceptance as a limited diesel fuel alternative in compression ignition engines. For the reliable implementation of biodiesel in commercial sectors, its effect on engine combustion, emission, and performance needs to be examined experimentally. In this study, 10% (N10) and 20 % (N20) Neem oil methyl ester (NME) blends were tested in a direct injection 4-stroke single-cylinder diesel engine incorporated with 5% and 10% exhaust gas recirculation (EGR). At maximum load conditions, Brake thermal efficiency (BTE) was found highest for N20 by 7.2%, and also Brake specific energy consumption (BSEC) was reduced by 11.4% for N20 as compared to diesel. Meanwhile, the incorporation of EGR deteriorates the performance parameters for the N20 blend. The results of emission analysis showed that oxides of nitrogen (NOx) increased with the addition of biodiesel whereas the addition of EGR diminished the NOx value for both biodiesel blends at all loading conditions. Unburnt hydrocarbon (UHC), Carbon monoxide (CO), and smoke emissions decreased by 40.6%, 31.2%, and 29.6% for the N20 blend respectively at full load when compared to diesel. Interestingly, when EGR was provided, CO, UHC, and smoke density values are increased for both N10 and N20 blends at all loading conditions, however lower than diesel operation.

Sıkıştırma oranının dizel motorun emisyon ve performans karakteristiklerine etkisinin Diesel RK yazılımı kullanılarak incelenmesi

The main purpose of this study is to observe the effects of compression ratio (CR) on the performance and emission characteristics of a single-cylinder diesel engine operating with fuels obtained by adding methanol and Al2O3 nanoparticles to diesel fuel. For this purpose, Diesel RK software was used and a simulation model was created. The simulation model created was verified with the previous experimental study and a maximum error of 6.5% was obtained. After the model was validated, analyses were performed at different compression ratios as 16.5, 17.5 and 18.5. Analyses were carried out at 1500 rpm constant engine speed and full load. In the results, it was observed that the brake specific fuel consumption (BSFC) and NOx values increased as the compression ratio increased for all test fuels. The minimum BSFC value was obtained in diesel fuel as 219 g/kWh at a compression ratio of 16.5. The minimum NOx value was obtained in M15A100 (test fuel obtained by adding 100 ppm Aluminium oxide nanoparticles to the test fuel called M15, which consists of 15% methanol, 85% diesel fuel by volume) fuel as 651 ppm at a compression ratio of 16.5.

Inventory of Commercial Cooking Activities and Emissions in a Typical Urban Area in Greece

The pollutants emitted during meal preparation in restaurants deteriorate the air quality. Thus, it is an environmental issue that needs to be addressed, especially in areas where these activities are densely located. The purpose of this study is to examine the impact on air quality from commercial cooking activities by performing a qualitative and quantitative analysis of the related parameters. The area of interest is located in the southeastern Mediterranean (Greater Athens area in Greece). Due to the lack of the necessary activity information, a survey was conducted. Emissions from the fuel burnt during the cooking procedures were calculated and it was found that, overall, 940.1 tonnes are attributed to commercial cooking activities annually (generated by classical pollutants, heavy metals, particulates and polycyclic aromatic hydrocarbon emissions). Comparing the contribution of different sources to the pollutants emitted, it was found that commercial cooking is responsible for about 0.6%, 0.8% and 1.0% of the total CO, NOx and PM10 values. Cooking organic aerosol (COA) and volatile organic compound (VOC) emissions from grilled meat were also calculated, accounting for 724.9 tonnes and 37.1 tonnes, respectively. Monthly, daily and hourly profiles of the cooking activities were developed and emissions were spatially disaggregated, indicating the city center as the area with higher values. Numerical simulations were performed with the WRF/CAMx modeling system and the results revealed a contribution of about 6% to the total PM10 concentrations in the urban center, where the majority of restaurants are located.

Experimental assessment on performance, emission and combustion characteristics of the use of diesel-acetylene mixtures at different loads in a ci engine

The current test was completed on a three-cylinder, liquid-cooled, naturally aspirated, indirect injection with injector pump on the head, compression ignition (CI) engine at 1500 rpm under changing load conditions. Acetylene was pumped as a secondary gaseous fuel into the intake port at various flow rates, while diesel was fed into the cylinder immediately as a primary fuel. The rate of gas flow was set at 200 g/h and 400 g/h, respectively. Tests were conducted at %0, %25, %50, %75 and %100 load conditions at above acetylene mass. In terms of combustion parameters, the results were assayed and compared. Acetylene induction reduced brake thermal efficiency (BTE) across all load settings. The highest BTE of 34.91 percent was attained for baseline diesel in the experiments. Acetylene is added to diesel fuel causes increased CO, HC, and NOx values when compared to conventional diesel combustion but soot was decreased. On the other hand, there is no significant change in CO2 emissions.

Promoting Pedestrian Transportation to Reducing Air Pollution from Urban Transport

Increasing air pollution around the world causes many problems, especially in the field of health. Air pollution affects not only human health but also other living things' health. The factors that cause air pollution the most are heating, industry, and transportation. Many countries in the world carry out various studies to reduce the effect of these factors on air pollution. Especially in the field of transportation, studies have been done quite a lot in recent years. In this study, air pollution caused by transportation in Erzurum, Turkey has been investigated. Emission amounts of NOX, PM10, and SO2 values have been calculated according to the types of vehicles in the city. Then, the amount of emissions from transportation in the total sector has been revealed. The transportation structure of the city has examined in general terms and the missing aspects in terms of pedestrian transportation have been revealed. Finally, some solution proposals aiming to encourage the use of pedestrian transportation and micro mobility vehicles in order to reduce motor land vehicles are presented.

Investigation of the effect of JP-8 fuel and biodiesel fuel mixture on engine performance and emissions by experimental and statistical methods

In this study, the effects of JP-8 military aviation fuel and biodiesel sunflower oil on the performance and emissions of the internal combustion engine were investigated by creating a mixture of fuel in different concentrations. Experimental and statistical methods were used in the study process. All of the experiments were carried out on an experimental setup with a single-cylinder compression-ignition engine at 7.5, 12.5 and 17.5 Nm engine load conditions. A total of 5 different fuels were used, including pure JP-8 fuel, 3 different blended fuels and pure biodiesel fuel. The design of the Response Surface Method, which is used as a statistical method, was carried out with Central Composite Design in the Design Exper 11 program environment. After the created design, 13 different experiments were carried out. With the tests performed, the values of IMEP, BSFC, COVimep, ignition delay, equivalence ratio, exhaust gas temperature, CO, and NOx emission response parameters were determined. Quadratic models were created by performing variance analysis for the response parameters obtained. After the optimization, it was concluded that the engine load should be 14.49 Nm and the JP-8 fuel biodiesel ratio should be 2.47%. In case the internal combustion engine is operated with optimum input parameters, IMEP value is 3.71 bar, BSFC value is 193.46 g/kWh, COVimep value is 5.99 bar, CO value is 724 ppm and NOx value is 168.62 ppm.