Latitudinal variation of the effect of aviation NOx emissions on atmospheric ozone and methane and related climate metrics

We evaluate the response to regional and latitudinal changes in aircraft NOx emissions using several climate metrics (radiative forcing (RF), Global Warming Potential (GWP), Global Temperature change Potential (GTP)). Global chemistry transport model integrations were performed with sustained perturbations in regional aircraft and aircraft-like NOx emissions. The RF due to the resulting ozone and methane changes is then calculated. We investigate the impact of emission changes for specific geographical regions (approximating to USA, Europe, India and China) and cruise altitude emission changes in discrete latitude bands covering both hemispheres. We find that lower latitude emission changes (per Tg N) cause ozone and methane RFs that are about a factor of 6 larger than those from higher latitude emission changes. The net RF is positive for all experiments. The meridional extent of the RF is larger for low latitude emissions. GWPs for all emission changes are positive, with tropical emissions having the largest values; the sign of the GTP depends on the choice of time horizon.

Biogenic nitric oxide emissions from soils: impact on NOx and ozone over West Africa during AMMA (African Monsoon Multidisciplinary Analysis) - observational study

Chemical and meteorological parameters measured on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 Atmospheric Research Aircraft during the African Monsoon Multidisciplinary Analysis (AMMA) campaign are presented to show the impact of NOx emissions from recently wetted soils in West Africa. NO emissions from soils have been previously observed in many geographical areas with different types of soil/vegetation cover during small scale studies and have been inferred at large scales from satellite measurements of NOx. This study is the first dedicated to showing the emissions of NOx at an intermediate scale between local surface sites and continental satellite measurements. The measurements reveal pronounced mesoscale variations in NOx concentrations closely linked to spatial patterns of antecedent rainfall. Fluxes required to maintain the NOx concentrations observed by the BAe-146 in a number of cases studies and for a range of assumed OH concentrations (1×106 to 1×107 molecules cm−3) are calculated to be in the range 8.4 to 36.1 ng N m−2 s−1. These values are comparable to the range of fluxes from 0.5 to 28 ng N m−2 s−1 reported from small scale field studies in a variety of non-nutrient rich tropical and sub-tropical locations reported in the review of Davidson and Kingerlee (1997). The fluxes calculated in the present study have been scaled up to cover the area of the Sahel bounded by 10 to 20 N and 10 E to 20 W giving an estimated emission of 0.03 to 0.30 Tg N from this area for July and August 2006. The observed chemical data also suggest that the NOx emitted from soils is taking part in ozone formation as ozone concentrations exhibit similar fine scale structure to the NOx, with enhancements over the wet soils. Such variability can not be explained on the basis of transport from other areas. Delon et al. (2008) is a companion paper to this one which models the impact of soil NOx emissions on the NOx and ozone concentration over West Africa during AMMA. It employs an artificial neural network to define the emissions of NOx from soils, integrated into a coupled chemistry-dynamics model. The results are compared to the observed data presented in this paper. Here we compare fluxes deduced from the observed data with the model-derived values from Delon et al. (2008).

NOx and CO emissions and soot presence in partially premixed acoustically excited flames

The pulsating combustion process has attracted interest in current research because its application in energy generation can offer several advantages, such as fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with other new techniques of combustion. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides, and soot presence in partial premixed flames in confined partially premixed liquefied petroleum gas flames. The results basically showed that a more uniform fuel/air mixture due to the presence of an acoustic field increases the NOx emissions in operations close to stoichiometric equivalence ratios and the frequency is the most important parameter. Carbon monoxide and soot reduced significantly.

Modellierung der Ruß- und NOx-Emissionen des Dieselmotors

Diesel Engine, Soot- and NOx-Emissions, Potency Product Approaches, zero-dimensional Models, optical and thermodynamical Methods, semi-empirical, Combustion Strategy, Injection Rate Shape

FCC-yksikön NOx-päästöjen hallinta

Työssä tutkittiin typen oksidien (NOx) päästöjen muodostumista ja NOx-päästöjen poistomenetelmiä leijukatalyyttisessa krakkausyksikössä (FCC). Koeajossa Porvoon öljynjalostamon FCC-yksikössä tutkittiin NOx-päästöjen hallintaa CO-promoottorin (CO:n palamista edistävä lisäaine) annostelun avulla. Kirjallisuusosassa käsiteltiin NOx-päästöjen muodostumista FCC-yksikön regeneraattorissa. Katalyyttisten lisäaineiden vaikutusta NOx-päästöjen muodostumiseen tarkasteltiin laajasti. Katalyyttisten lisäaineiden ohella käsiteltiin muitakin NOx-päästöjen poistomenetelmiä. Koeajojen tarkoituksena oli optimoida FCC-yksikön katalyyttikiertoon annosteltavan CO-promoottorin määrä. CO-promoottorin sisältämä platina lisää NOx-päästöjen muodostumista regeneraattorissa, mutta vähentää jälkipalamista. Jälkipalamisen vuoksi regeneraattorin ylimenolinjan lämpötila nousee. Regeneraattorin ylimenolinjan lämpötila oli CO-promoottorin vähentämistä rajoittava tekijä, NOx-päästöjä pyrittiin vähentämään ilman merkittävää jälkipalamisen kasvua. Tuorekatalyytin platinapitoisuuden pienentäminen vähentää merkittävästi NOx-päästöjä.

Design and development of a low NOx Coanda ejector burner

Small gaseous combustion systems are being targeted by strict pollution legislation which will provide challenges to reduce the NOx being emitted. A novel type of gas burner has been successfully designed and developed which incorporates a Coanda ejector to promote recirculation of flue gas from the burner exit. This provides a combustion system which gives very low emissions of NOx and CO, whilst maintaining a high degree of flame stability over a range of air/fuel ratios and fuel flow rates. Recirculation of flue gas was obtained by manipulating the aerodynamics of the system, without the aid of external duct work or moving parts. The design of the burner allowed very low pollutant emissions near stoichiometric conditions, resulting in high temperatures of the exit gas. Potential applications of this type of burner are in small and intermediate furnaces where low NOx emissions are required. Moreover, very high-temperature applications, such as glass furnaces could benefit in both cost and pollutant emissions from such a burner.

Study of utilization of petrol engine equipped with exhaust gas recirculation (EGR) and catalytic converter to reduce consumption and NOx emission

Study of consumption rate and gaseous pollutant emission from engine tests simulating real work conditions, using spark point manually controlled and exhaust gas recirculation (EGR) in diverse proportion levels. The objective of this work is to re-examine the potential of the EGR conception, a well-known method of combustion control, employed together electronic fuel injection and three-way catalytic converter closed-loop control at a spark ignition engine, verifying the performance characteristics and technical availability of this conception to improve pollution control, fuel economy at low torque drive condition and to improve the engine exhaust components useful life. The pollutant emissions and consumption levels under operational conditions simulations were analysed and compared with the expected by concerning theory and real tests performed by EGR equipped engines by factory. Copyright © 2006 Society of Automotive Engineers, Inc.

Proposal of a dynamic performance index to analyze driving pattern effect on car emissions

The contributions of driver behaviour as well as surrounding infrastructure are decisive on pollutant emissions from vehicles in real traffic situations. This article deals with the preliminary study of the interaction between the dynamic variables recorded in a vehicle (driving pattern) and pollutant emissions produced over a given urban route. It has been established a “dynamic performance index”-DPI, which is calculated from some driving pattern parameters, which in turn depends on traffic congestion level and route characteristics, in order to determine whether the driving has been aggressive, normal or calm. Two passenger cars instrumented with a portable activity measurement system -to record dynamic variables- and on-board emission measurement equipment have been used. This study has shown that smooth driving patterns can reduce up to 80% NOX emissions and up to 20% of fuel in the same route

How lowering speed limits in an urban highway affects traffics performance and emissions: the case of Madrid M-30 ring-road

The city of Madrid keeps not meeting the GHG and air pollutant limits set by the European legislation. A broad range of strategies have being taken into account to reduce both types of emissions; however traffic management meas ures are usually consigned to the sidelines. In 2004, Madrid City Council launched a plan to re-design its inner ring-road supported by a socioeconomic study that evaluated the environmental and operational benefits of the project. For safety reasons the planned speed limit for the tunnel section was finally reduced from 90km/h to 70km/h. Using a Macroscopic Traffic Model and the European Air Pollutant and Emissions Inventory Guidebook (EMEP/EEA), this paper examines the environmental and traffic performance consequences of this decision. Results support the thesis that reduced speed limits leads to GHG and air pollution reductions in the area affected by the measure without substantially altering traffic performance. The implementation of the new speed limit policy brings about a 15% and 16% reduction in both CO2 and NOx emissions respectively. Emissions’ reduction during off-peak hours is larger than during peak hours.

Understanding how to reduce road transport emissions : modelling the impact of eco-driving

Entre los problemas medioambientales más trascendentales para la sociedad, se encuentra el del cambio climático así como el de la calidad del aire en nuestras áreas metropolitanas. El transporte por carretera es uno de los principales causantes, y como tal, las administraciones públicas se enfrentan a estos problemas desde varios ángulos: Cambios a modos de transporte más limpios, nuevas tecnologías y combustibles en los vehículos, gestión de la demanda y el uso de tecnologías de la información y la comunicación (ICT) aplicadas al transporte. En esta tesis doctoral se plantea como primer objetivo el profundizar en la comprensión de cómo ciertas medidas ICT afectan al tráfico, las emisiones y la propia dinámica de los vehículos. El estudio se basa en una campaña de recogida de datos con vehículos flotantes para evaluar los impactos de cuatro medidas concretas: Control de velocidad por tramo, límites variables de velocidad, limitador de velocidad (control de crucero) y conducción eficiente (eco‐driving). Como segundo objetivo, el estudio se centra en la conducción eficiente, ya que es una de las medidas que más ahorros de combustible presenta a nivel individual. Aunque estas reducciones están suficientemente documentadas en la literatura, muy pocos estudios se centran en estudiar el efecto que los conductores eficientes pueden tener en el flujo de tráfico, y cuál sería el impacto si se fuera aumentando el porcentaje de este tipo de conductores. A través de una herramienta de microsimulación de tráfico, se han construido cuatro modelos de vías urbanas que se corresponden con una autopista urbana, una arteria, un colector y una vía local. Gracias a los datos recogidos en la campaña de vehículos flotantes, se ha calibrado el modelo, tanto el escenario base como el ajuste de parámetros de conducción para simular la conducción eficiente. En total se han simulado 72 escenarios, variando el tipo de vía, la demanda de tráfico y el porcentaje de conductores eficientes. A continuación se han calculado las emisiones de CO2 and NOx mediante un modelo de emisiones a nivel microscópico. Los resultados muestran que en escenarios con alto porcentaje de conductores eficientes y altas demandas de tráfico las emisiones aumentan. Esto se debe a que las mayores distancias de seguridad y las aceleraciones y frenadas suaves hacen que aumente la congestión, produciendo así mayores emisiones a nivel global. Climate change and the reduced air quality in our metropolitan areas are two of the main environmental problems that the society is addressing currently. Being road transportation one of the main contributors, public administrations are facing these problems from different points of view: shift to cleaner modes, new fuels and vehicle technologies, demand management and the use of information and communication technologies (ICT) applied to transportation. The first objective of this thesis is to understand how certain ICT measures affect traffic, emissions and vehicle dynamics. The study is based on a data collection campaign with floating vehicles to evaluate the impact of four specific measures: section speed control, variable speed limits, cruise control and eco‐driving. The second objective of the study focuses on eco‐driving, as it is one of the measures that present the largest fuel savings at an individual level. Although these savings are well documented in the literature, few studies focus on how ecodrivers affect the surrounding vehicles and the traffic, and what would be the impact in case of different eco‐drivers percentage. Using a traffic micro‐simulation tool, four models in urban context have been built, corresponding to urban motorway, urban arterial, urban collector and a local street. Both the base‐case and the parameters setting to simulate eco‐driving have been calibrated with the data collected through floating vehicles. In total 72 scenarios were simulated, varying the type of road, traffic demand and the percentage of eco‐drivers. Then, the CO2 and NOx emissions have been estimated through the use of an emission model at microscopic level. The results show that in scenarios with high percentage of co‐drivers and high traffic demand the emissions rise. Higher headways and smooth acceleration and decelerations increase congestion, producing higher emissions globally.

Carbon nanotube-supported metal catalysts for NOx reduction using hydrocarbon reductants. Part 1:catalyst preparation, characterization and NOx reduction characteristics

A dual catalyst system for the Selective Catalytic Reduction of NOx with hydrocarbons (HC-SCR), including distinct low and high temperature formulations, is proposed as a means to abate NOx emissions from diesel engines. Given that satisfactory high temperature HC-SCR catalysts are already available, this work focuses on the development of an improved low temperature formulation. Pt supported on multiwalled carbon nantubes (MWCNTs) was found to exhibit superior NOx reduction activity in comparison with Pt/Al2O3, while the MWCNT support displayed a higher resistance to oxidation than activated carbon. Refluxing the MWCNT support in a 1:1 mixture of H2SO4 and HNO3 prior to the metal deposition step proved to be beneficial for the metal dispersion and the NOx reduction performance of the resulting catalysts. This support effect is ascribed to the increased Brønsted acidity of the acid-treated MWCNTs, which in turn enhances the partial oxidation of the hydrocarbon reductant. Further improvements in the HC-SCR performance of MWCNT-based formulations were achieved using a 3:1 Pt–Rh alloy as the supported phase.

OBSERVATIONS AND EMISSIONS OF ENERGY-ASSOCIATED OZONE PRECURSORS IN THE MID-ATLANTIC UNITED STATES

Surface ozone is formed in the presence of NOx (NO + NO2) and volatile organic compounds (VOCs) and is hazardous to human health. A better understanding of these precursors is needed for developing effective policies to improve air quality. To evaluate the year-to-year changes in source contributions to total VOCs, Positive Matrix Factorization (PMF) was used to perform source apportionment using available hourly observations from June through August at a Photochemical Assessment Monitoring Station (PAMS) in Essex, MD for each year from 2007-2015. Results suggest that while gasoline and vehicle exhaust emissions have fallen, the contribution of natural gas sources to total VOCs has risen. To investigate this increasing natural gas influence, ethane measurements from PAMS sites in Essex, MD and Washington, D.C. were examined. Following a period of decline, daytime ethane concentrations have increased significantly after 2009. This trend appears to be linked with the rapid shale gas production in upwind, neighboring states, especially Pennsylvania and West Virginia. Back-trajectory analyses similarly show that ethane concentrations at these monitors were significantly greater if air parcels had passed through counties containing a high density of unconventional natural gas wells. In addition to VOC emissions, the compressors and engines involved with hydraulic fracturing operations also emit NOx and particulate matter (PM). The Community Multi-scale Air Quality (CMAQ) Model was used to simulate air quality for the Eastern U.S. in 2020, including emissions from shale gas operations in the Appalachian Basin. Predicted concentrations of ozone and PM show the largest decreases when these natural gas resources are hypothetically used to convert coal-fired power plants, despite the increased emissions from hydraulic fracturing operations expanded into all possible shale regions in the Appalachian Basin. While not as clean as burning natural gas, emissions of NOx from coal-fired power plants can be reduced by utilizing post-combustion controls. However, even though capital investment has already been made, these controls are not always operated at optimal rates. CMAQ simulations for the Eastern U.S. in 2018 show ozone concentrations decrease by ~5 ppb when controls on coal-fired power plants limit NOx emissions to historically best rates.

Optimisation of environmental gas cleaning routes for solid wastes cogeneration systems - Part I - Analysis of waste incineration steam cycle

Research of advanced technologies for energy generation contemplates a series of alternatives that are introduced both in the investigation of new energy sources and in the improvement and/or development of new components and systems. Even though significant reductions are observed in the amount of emissions, the proposed alternatives require the use of exhaust gases cleaning systems. The results of environmental analyses based on two configurations proposed for urban waste incineration are presented in this paper; the annexation of integer (Boolean) variables to the environomic model makes it possible to define the best gas cleaning routes based on exergetic cost minimisation criteria. In this first part, the results for steam cogeneration system analysis associated with the incineration of municipal solid wastes (MSW) is presented. (c) 2007 Elsevier Ltd. All rights reserved.

Öljynjalostamon tyhjöyksikön esilämmitysuunin optimointi

Työn tarkoituksena oli vertailla kahta kaupallista prosessiuunisimulointiohjelmaa sekä selvittää onko toinen ohjelma soveltuva Neste Jacobs Oy:n käyttöön. Tavoitteena oli selvittää ohjelmien ominaisuuksien eroja ja rajoitteita sekä tuloksien yhdenmukaisuutta. Kirjallisuusosassa perehdyttiin prosessiuunien toimintaperiaatteisiin, yleisiin mitoitusperiaatteisiin ja säteilylämmönsiirron perusteisiin. Kirjallisuusosassa käsiteltiin myös prosessiuunien polttimien toimintaa ja NOx-päästöjä vähentäviä polttotekniikoita. Molemmilla laskentaohjelmilla laadittiin kuumaöljy- ja tyhjöuuni, joiden tuloksia vertailtiin tärkeimpien prosessiarvojen perusteella ja toisen ohjelman osalta myös laitevalmistajan ilmoittamiin arvoihin. Tällä ohjelmalla tutkittiin tyhjöuunin höyrynruiskutuksen ja koksaantumisen vaikutuksia prosessiin sekä säteilyosan leveyden muutoksen vaikutusta säteilylämmönsiirtoon. Ohjelmien ominaisuuksien keskeisimmät erot liittyivät kaksifaasivirtauksen laskentaan, prosessiaineen massavirran rajoituksiin, ilman esilämmittimen käyttöön ja laskentamallien paineen kontrollointiin. Tulokset erosivat savukaasun ja tuubien lämpötilojen ja painehäviön laskennassa. Tuloksien ja ominaisuuksien perusteella toisen ohjelman ei todettu olevan täysin soveltuva Neste Jacobs Oy:n käyttöön.

Combustibility of Paper Mill Rejects

Tämän työn tarkoituksena oli selvittää mekaanisen massan valmistuksen käsittävän paperitehtaan rejektija jätevirtojen poltettavuutta, jos paperitehtaan vesikiertojen sulkemisastetta lisätään. Jotta prosessin tilannetta sulkemisen jälkeen saatiin arvioitua, Anjalan paperitehtaan nykypäivän PK3:n prosessia tutkittiin kuorimolta jätevesilaitokselle. Kirjallisuusosassa käsiteltiin rejekti- ja jätevirtojen alkuperää mekaanista massaa käyttävässä paperitehtaassa. Myös tämän päivän jätevedenkäsittelyprosessit sekä sulkemisessa mahdolliset prosessiveden puhdistustekniikat esiteltiin lyhyesti. Lisäksikäytiin läpi nykypäivänä metsäteollisuudessa käytössä olevat polttotekniikat sekä polttoaineiden karakterisointi kattilan käytettävyyden ja päästöjen kannalta. Anjalan PK3:lla käytetään sekä peroksidi- että ditioniittivalkaistua tai pelkästään ditioniittivalkaistua hioketta riippuen tuotannossa olevasta lajista. PK3-prosessissa syntyneet jätevesi-, liete- ja muut jätevirrat selvitettiin molemmissa valkaisuolosuhteissa. Prosessin eniten liuennutta orgaanista ainesta sisältävät jätevesijakeet, 3-hiomon kuumankierron ja kirkassuodoksen ulosajot sekä kuoripuristimen suodos, valittiin puhdistettaviksi virroiksi prosessin sulkemista arvioitaessa. Kun peroksidivalkaisua käytettiin 3-hiomolla, TOC-kuorma jokeen oli 30 % suurempi kuin pelkällä ditioniittivalkaisulla. Jos prosessin sulkemisastetta lisättäisiin, TOC-kuorma olisi 30 %pienempi kuin tänäpäivänä peroksidivalkaisua käytettäessä (80 % puhdistustehokkuudella). Prosessin sulkemisastetta lisättäessä biolietettä muodostuisi n. 30 % vähemmän verrattuna nykytilanteeseen, sillä mikrobien ravintona käyttämää orgaanista ainesta päätyisi vähemmän jäteveteen. 3-hiomon peroksidivalkaisun vaikutus kattilan käytettävyyteen ja päästöihin oli pieni, sillä biolietteen osuus polttoaineen syötöstä oli vain 4 %. Vain osa biolietteestä muodostui 3-hiomolta peräisin olevaa orgaanista ainesta poistettaessa. Jos nykyisen pääpolttoaineen, PDF:n,osuuden jättää huomioimatta, SO2- ja NOx-päästöt sekä leijupedin sintrautuvuus ovat hiukan suuremmat käytettäessä peroksidivalkaisua 3-hiomolla kuin pelkästään ditioniittivalkaisulla. Jos kuoripuristimen ja hiomon suodosten puhdistuksen konsentraatit johdetaan poltettaviksi BFB-tyyppiseen kattilaan, leijupedin sintrautuminen tulisi olemaan suurin ongelma. Myös raskasmetalli-, SO2- ja NOx-päästöt lisääntyisivät merkittävästi verrattuna nykyiseen tilanteeseen. Sen sijaan kattilan korroosioriski tuskin lisääntyisi. Lisäksi konsentraattien kosteuspitoisuus olisi korkea, mikä tekisi poltosta kannattamatonta veden haihdutuksen vaatiessa paljon energiaa. Yksityiskohtaisempaa tutkimusta tarvitaan vielä prosessin sulkemisen vaikutuksista päästöihin ja kattilan käytettävyyteen. Myös muita konsentraattien hävittämismahdollisuuksia tulisi tutkia lisää.