NOx Emission

Bioethanol-gasoline blends represent for Otto-cycle engines a consolidated alternative in the attempts to reduce GHG emissions and to limit the use of fossil fuels. However, the use of alternative fuels can strongly influence the performance of engines.
The purpose of this study is to analyse the output and the pollutant emissions of a four-stroke SI engine fuelled with 0%, 50% and 80% bioethanol-gasoline blends. Tests were performed on a 3-kW engine used in broad applications. No specific modifications were applied to the carburetion system in order to evaluate its fuel flexibility capabilities.
The tests evidenced that the mixture tends to get lean with alcoholic fuels; the brake specific fuel consumption increased due to the lower LHV of bioethanol, while the highest brake thermal efficiency was obtained with E50. Minor torque and power reductions were recorded with the ethanol blends. The concentration of UHC decreased with E50 and E80 while NOx emissions reduced because of the lower combustion temperature due to the bioethanol cooling effect and the leaner mixture. In contrast, the concentration of CO increased because a poor homogenization of the charge and a lower combustion temperature had facilitated the formation of partial oxidation products.

The effect of biofuel blends on the engine performance and emissions of agricultural machines can be extremely complex to predict even if the properties and the effects of the pure substances in the blends can be sourced from the literature. Indeed, on the one hand, internal combustion engines (ICEs) have a high intrinsic operational complexity; on the other hand, biofuels show antithetic effects on engine performance and present positive or negative interactions that are difficult to determine a priori. This study applies the Response Surface Methodology (RSM), a numerical method typically applied in other disciplines (e.g., industrial engineering) and for other purposes (e.g., setup of production machines), to analyse a large set of experimental data regarding the mechanical and environmental performances of an ICE used to power a farm tractor. The aim is twofold: i) to demonstrate the effectiveness of RSM in quantitatively assessing the effects of biofuels on a complex system like an ICE; ii) to supply easy-to-use correlations for the users to predict the effect of biofuel blends on performance and emissions of tractor engines. The methodology showed good prediction capabilities and yielded interesting outcomes. The effects of biofuel blends and physical fuel parameters were adopted to study the engine performance. Among all possible parameters depending on the fuel mixture, the viscosity of a fuel blend demonstrated a high statistical significance on some system responses directly related to the engine mechanical performances. This parameter can constitute an interesting indirect estimator of the mechanical performances of an engine fuelled with such blend, while it showed poor accuracy in predicting the emissions of the ICE (NO x , CO concentration and opacity of the exhaust gases) due to a higher influence of the chemical composition of the fuel blend on these parameters; rather, the blend composition showed a much higher accuracy in the assessment of the mechanical performance of the ICE.

A liquid bio-fuel burner system with various radial air swirlers attached to combustion chamber of 280 mm inside diameter and 1000 mm length has been investigated. All tests were conducted using crude palm oil as fuel. A radial flow air swirler with curved blades having 50 mm outlet diameter was inserted at the inlet plane of the combustor to produce swirling flow. Fuel was injected at the back plate of the swirler outlet using central fuel injector with single fuel nozzle pointing axially outwards. The swirler vane angles and equivalence ratios were varied. Tests were carried out using four different air swirlers having 45°, 50°, 60°and 70° vane angles. NOx emissions reduction of about 12 percent was obtained at swirl number of 1.911 as compared to 0.780 at the same equivalence ratio of 0.83. In addition, emission of carbon monoxide decreased as the swirl number increased. The results shows that a proper design of air swirler has a great effect on mixing process and hence the combustion and emission.

The article deals with the issue of reducing the formation of nitrogen oxides in the boundary conditions of combustion. These conditions occur at a high thermal load of the combustion chamber, while the amount of nitrogen oxides increases exponentially according to the Arrhenius formula. Due to this, special attention must be paid to the combustion of natural gas, especially because there is a constant demand for minimizing the formation of pollutants. The simulation model of a steam boiler with 4 industrial gas burners (heat output of each is 17.8 MW) and the high thermal load of the combustion chamber (0.59 MW.m-3) is presented in the paper. Simulation modelling and subsequent experimental measurements on a real object show how classical primary de-NOx methods manifest themselves under extreme thermal loads. The result of the research is a significant reduction in NOx production, which was achieved by a combination of primary methods.

El uso de diversos combustibles, el incremento de la urbanización, y el desarrollo económico, han influido en la generación de contaminantes atmosféricos, tales como los NOx (óxidos de nitrógeno), el SO2 (dióxido de azufre) y las PTS (partículas totales en suspensión). El sector industrial en Costa Rica cuenta con empresas de diferentes categorías como las de elaboración de productos alimenticios, fundición de vidrio, fabricación de prendas de vestir, entre otras, las cuales generan en sus procesos, emisiones de estos compuestos a la atmósfera. El presente proyecto de investigación tiene como objetivo principal generar un inventario preliminar de las emisiones atmosféricas (NOX, SO2 y PTS) de diferentes sectores industriales de Costa Rica. El inventario se realizó durante el 2019, considerando los resultados de muestreos y mediciones de los contaminantes provenientes de las chimeneas de diferentes procesos productivos (empresas) durante los años 2014 y 2015. El muestreo y la correspondiente medición de la concentración de los contaminantes (NOX, SO2 y PTS) se llevó a cabo mediante el uso del Testo 350 para la medición de los NOx y del SO2, y el contador portátil de partículas marca APEX para la cuantificación de PTS. La tabulación de datos utilizó el programa Microsoft Excel, utilizándose además el lenguaje de programación R, en la interfaz de R Studio para la generación de los gráficos. El sector industrial “elaboración de productos alimenticios” reporta las mayores concentraciones de contaminantes, con valores de 1 246,14 ton/año, 1 959,54 ton/año y 651,01 ton/año para NOX, SO2 y PTS, respectivamente en el 2014; y 2 622,14 ton/año, 3 257,64 ton/año y 346,40 ton/año respectivamente para el 2015 en estos mismos contaminantes.

Using hydrogen as an alternative fuel in spark-ignition engines has great potential for reducing exhaust emissions. Hydrogen engines have CO 2 -and HC-free combustion and lean operation, offering lower nitrogen oxide (NO x) emission. In this paper, a numerical study of a direct injection spark-ignition (DISI) hydrogen-fueled engine was conducted via 3-dimensional computational fluid dynamics (CFD) methods and results were compared with experimental data, showing good agreement. Injection timing, initial charge temperature, and initial charge pressure were selected as effective and controllable parameters of emissions and performance characteristics. Results showed that mixture homogeneity was more affected by injection timing, and advancing the injection timing led to improved engine performance with a slight increase in NO x emissions. Increasing the initial pressure and decreasing the initial temperature led to better engine performance and reduced NO x emissions in the DISI hydrogen-fueled engine.

Increasing the performance of an internal combustion engine requires the transformation of total fuel energy to useful energy at the highest as possible. Increase of inner cylinder heat plays important role in the increase of engine performance and decrease of exhaust emissions. It is understood as a result of literature studies that coating combustion chamber elements with thermal barriers contributes a lot to the increase of inner cylinder heat. This study includes an evaluation of experimental studies and its results carried out upon the methods applied on coating with thermal barrier in diesel engines, the effects of coating on the performance of engine and exhaust emissions.

Thesis by William Stephen Bulpitt, 1972, 136 pages
Georgia Institute of Technology
Deals with an early Mazda 10A rotary engine (R100)

> Contents ...
> Acknowledgments  4
> Table of contents  5
> List of tables  7
> List of illustrations  8
> Summary  10
> Chapter 1 - Introduction  12
  » The problem of automotive air pollutants  12
  » The Wankel engine + its development  15
  » Emission standards + current methods of abatement  20
  » Natural gas as a motor fuel  27
> Chapter 2 - Description of Apparatus  32
  » Laboratory concept  32
  » Wankel test setup  34
  » Emissions instrumentation + sampling train  45
  » Hydrocarbons (FID)  46
  » Nitric Oxide (NDIR)  50
  » Carbon Dioxide (NDIR)  51
  » Carbon Monoxide + Hydrocarbons (NDIR)  51
> Chapter 3 - Experimental Procedure  59
  » Original plan for experiments  59
  » Parameters to be studied  59
  » Ignition timing  61
  » Fuel mixture  62
  » Alternate fuels  63
  » Final testing program  63
  » Test procedure  68
  » Sources of error  71
> Chapter 4 - Results  76
  » Data taking + data reduction  76
  » Meaningful data relationships  77
  » A. Emissions variations with engine speed  77
  » B. Emissions variations with engine load  77
  » C. Emissions variations with ignition timing  80
  » D. Emissions with mixture variation  84
  » E. Horsepower variations with different fuels + mixtures  91
  » F. Horsepower variations with timing  91
  » Discussion of results  96
      » A. Emissions variation with engine speed  96
      » B. Emissions variation with engine load  98
      » C. Emission variations with ignition timing  99
      » D. Emission variations with mixture  100
      » E. Horsepower variation with fuel  102
      » F. Horsepower variation with ignition timing  102
> Chapter 5 - Conclusions  103
> Chapter 6 - Recommendations  106
> Appendix A - Sample calculation of air-fuel ratio  107
> Appendix B - Correction for exhaust dilution  112
> Appendix C - Tables  114
> Bibliography  135

german keywords: Wankelmotor / Kreiskolbenmotor
English Keywords: Wankel Engine / Wankel Rotary Engine / Rotary Piston Engine / Rotary Combustion Engine

In presenting the dissertation as a partial fulfillment of the requirements for an advanced degree from the Georgia Institute of Technology, I agree that the Library of the Institute shall make it available 'or inspection and circulation in accordance with its regulations governing materials of this type. I agree that permission to copy from, or to publish from, this dissertation may be granted by the professor under whose direction it v/as written, or, in his absence, by the Dean of the Graduate Division //hen such copying or publication is solely for scholarly purposes ar.d does not involve potential financial gain. If is unders ood that any copying from, or publication of. this dissertation which involves potential financial gain will not be allowed wi thoufc wr111en permis sIon .

Nitrogen oxide (NOx) emissions from passenger cars (PCs) in the Republic of Croatia have been on the increase since 2014. Additionally, particulate matter (PM) emissions are not on the decline, but have been stagnating since 2015. (Resetar et al., 2017). The reason for this is the increase in vehicle exploitation that comes as a result of Croatia’s recovery from the 2008 – 2013 economic crisis. Aside from that, Croatia’s 2013 entry into the EU has resulted in an increased number of used PCs imported from the EU. Emissions from these used PCs are substantially higher than those of new PCs, whose sales have been slashed in half after 2008. The current trend is an increase of PCs in Croatia, which is bound to result in an overall increase of emissions. In order to apply justified emission reducing measures it is necessary to assess the main sources of pollution. In the case of harmful emissions, NOx and PM emissions are the ones that were examined. Exposure to increased concentrations of NOx and PM emissions is known to cause respiratory ailments, heart diseases, stroke and can be the cause of premature death (Guttikunda and Goel, 2013). The most severe problem is found in urban areas with high traffic density. It is well known that diesel- engine PCs generate the majority of harmful NOx and PM emissions. Additionally, recent research suggests that even the NOx emissions of newer diesel-engine PCs, which are in accordance with Euro 5 and Euro 6 emission standards, taken from real driving conditions are several times higher than the emission limit values prescribed by Regulation 715/2007 (O’Driscoll et al., 2016). A number of different criteria must be taken into account so as to determine which PC categories generate the most NOx and PM emissions. The following criteria have been taken into account in the scope of this research: fuel type, engine capacity, emission standard, driving mode, engine temperature (including cold start) and average annual vehicle mileage. The processed data on the PC fleet that underwent technical inspection in 2016 was gathered from the database of Centre for Vehicles of Croatia (CVH), the company whose primary activity is performing periodical technical inspections on vehicles in Croatia. This is a unique database that contains data on all vehicles registered in Croatia, including periodical technical inspection data and annual vehicle activity data. For relevant PC subcategories, emissions and implied emission factors for pollutants NOx and PM were calculated for the year 2016 using the COPERT 5 computer program.

Using hydrogen as an alternative fuel in spark-ignition engines has great potential for reducing exhaust emissions. Hydrogen engines have CO2- and HC-free combustion and lean operation, offering lower nitrogen oxide (NOx) emission. In this paper, a numerical study of a direct injection spark-ignition (DISI) hydrogen-fueled engine was conducted via 3-dimensional computational fluid dynamics (CFD) methods and results were compared with experimental data, showing good agreement. Injection timing, initial charge temperature, and initial charge pressure were selected as effective and controllable parameters of emissions and performance characteristics. Results showed that mixture homogeneity was more affected by injection timing, and advancing the injection timing led to improved engine performance with a slight increase in NOx emissions. Increasing the initial pressure and decreasing the initial temperature led to better engine performance and reduced NOx emissions in the DISI hydrogen-fueled engine.

The paper deals with the study of the influence of various factors, which have an impact on emissions such as NOx, CO, which have been verified by measurements. Biomass in the form of wood chips as fuel of different moisture content from 9% to 25% has been tested at various boiler outputs. The presented work also defines the mathematical dependencies of NOx and CO emission generation by using regression analysis from measured data after biomass combustion in low-power boilers. The paper also describes a mathematical model of biomass combustion. The mathematical model was created to verify the measured data and prediction of emission generation in the process of biomass combustion. This model consists of combustion of stoichiometry, calculation of combustion temperatures, obtained regression equations of NOx and CO. At the end of this paper, the obtained results are compared with the calculated models as well as the results of the defined dependencies from the regression analysis.

This work suggests an interpretation to the quantitatively higher formation of NOx in a compression ignition (CI) engine when fueled with pure biodiesel (B100). A comparative study about the use of rapeseed oil methyl ester (RME) and diesel fuel mixtures on injection timing, in-chamber pressure, heat release rate, and NOx emissions were carried out using a diesel engine equipped with a pump-line-nozzle injection system. Such engines are still widely adopted mainly in agriculture, as the fleet of agricultural machinery is particularly old (often over 20 years) and the use of biofuels can reduce the environmental footprint of the sector. This work aims to supply some general explanations and figures useful to interpret the phenomena occurring within the fuel line and in the combustion process when using biodiesel, as well as in engines with different construction characteristics and fueling systems. Given the contradictory results available in the literature, the so-called “biodiesel NOx effect” cannot be explained solely by the different physical properties of biodiesel (in particular, a higher bulk modulus). Experimental results show that, with the same pump settings, the start of injection with the RME is slightly advanced while the injection pressure values remain almost the same. With the RME, the pressure in the injection line increases faster due to its greater bulk modulus but the pressure rise starts from a lower residual pressure. The start of combustion takes place earlier, the heat release during the premixed phase is steeper, and a higher peak is reached. The NOx emissions with the RME are at least 9% higher when compared to mineral diesel fuel. The greater amount of the RME injected per cycle compensates for its minor lower heating value, and the brake torque at full load is similar to the two analyzed fuels. Finally, a variation of the pump line timing is evaluated in order to assess the effect of the delay and the advance of the injection on the performance of the engine and on the emissions. A viable and simple solution in the variation of the injection strategy is suggested to counterbalance the biodiesel NOx effect.

Pollution is one major factor which affects the environment nowadays, resulting in green house effect and global warming. Suitable methods are introduced to increase the engine fuel economy and bring down the emissions within the tolerable limit.

The use of fuels, urbanization growth, and economic development have influenced the generation of atmospheric pollutants such as NOx (nitrogen oxides), SO2 (sulfur dioxide), and TSPs (Total Suspended Particles). The Costa Rican industrial sector has different category companies such as glass melting and manufacturing of food products and clothing, which release emissions of these pollutants into the atmosphere. The main objective of this research is to generate a preliminary inventory of atmospheric emissions (NOx, SO2, and TSP) from different industrial sectors in Costa Rica. The inventory was conducted in 2019 and included samplings and measurements of pollutants from chimneys of different production processes (companies) from 2014 and 2015.  The sampling and the corresponding measurement of pollutant concentrations (NOx, SO2 and TSP) were conducted using Testo 350 to measure NOx and SO2 and an APEX portable particle counter to quantify TSPs. Data was tabulated using Microsoft Excel, while graphics were generated using R programming language in the R studio interface. The industrial sector entitled “manufacturing of food products” presents the highest amounts of pollutants, with values equal to 1246.14 tons/year, 1959.54 tons/year and 651.01 tons/year for NOx, SO2, and TSP, respectively, for 2014; and 2,622.14 tons/year, 3,257.64 tons/year and 346.40 tons/year, respectively, for 2015.

the western part of romania, i.e. Banat, is one of the most developed industrial areas of romania, with many urban agglomerations (timisoara, arad, lugoj, Jimbolia). thus, the regional air pollution monitoring and assessment are of paramount importance for the sustainable development of the society in the region. This work is focused on the identification of the air pollution regimes and specificity, as well as on the main driven factors. Representative ground measurements data sets of o 3 , no x , so 2 and PM10, will be analysed and presented in the context of regional photo-chemistry potential. The effect of the traffic through an urban region will be also analysed. Finally, the complementarily necessity of the lIDar-based observations for the evaluation of the vertical mixing structures, planetary boundary layer dynamics, and generated specific regional effects in the region will be demonstrated. Keywords: no x , lIDar, regional air pollution, aerosols, planetary boundary layer. aIMs anD BaCKGrounD the main purpose of this research is to identify the air pollution regimes and their specificity in the Timisoara city (urban episodes) and the majors sources of the pollution. In situ measurements were accomplished in different relevant locations in Timisoara, with or without traffic, in order to identify the traffic influences on air quality. Point monitor measurement equipments were used for monitoring the pollution level at ground surface and allowing the identification of pollution sources. our conclusion is that in spite of the usefulness of these measured values and the information generated by the processing of the data there is not sufficient relevant information for identifying at a regional scale the dynamics of the atmosphere over the urban area and more particular the aerosols height distribution and their

One of the elements of strategy aimed at minimizing the impact of road transport on air quality is the introduction of its reorganization resulting in decreased pollutant emissions to the air. The aim of the study was to determine the optimal strategy of corrective actions in terms of the air pollutant emissions from road transport. The study presents the assessment results of the emission reduction degree of selected pollutants (PM 10 , PM 2.5 , and NO x) as well as the impact evaluation of this reduction on their concentrations in the air for adopted scenarios of the road management changes for one of the street canyons in Krakow (Southern Poland). Three scenarios under consideration of the city authorities were assessed: narrowing the cross-section of the street by eliminating one lane in both directions, limiting the maximum speed from 70 km/h to 50 km/h, and allowing only passenger and light commercial vehicles on the streets that meet the Euro 4 standard or higher. The best effects were obtained for the variant assuming banning of vehicles failing to meet the specified Euro standard. It would result in a decrease of the yearly averaged PM 10 and PM 2.5 concentrations by about 8-9% and for NO x by almost 30%.

Using hydrogen as an alternative fuel in spark-ignition engines has great potential for reducing exhaust emissions. Hydrogen engines have CO 2-and HC-free combustion and lean operation, offering lower nitrogen oxide (NO x) emission. In this paper, a numerical study of a direct injection spark-ignition (DISI) hydrogen-fueled engine was conducted via 3-dimensional computational fluid dynamics (CFD) methods and results were compared with experimental data, showing good agreement. Injection timing, initial charge temperature, and initial charge pressure were selected as effective and controllable parameters of emissions and performance characteristics. Results showed that mixture homogeneity was more affected by injection timing, and advancing the injection timing led to improved engine performance with a slight increase in NO x emissions. Increasing the initial pressure and decreasing the initial temperature led to better engine performance and reduced NO x emissions in the DISI hydrogen-fueled engine.