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The purpose of this study is to enhance control strategies for selective catalytic reduction (SCR) and ammonia slip catalyst (ASC) systems, aiming to effectively reduce NOx emissions from automotive engines during realistic driving cycles. Despite the effectiveness of these after-treatment systems (ATS), their dynamic and non-linear characteristics present significant challenges in achieving precise control. Therefore, this research proposes a hybrid approach that combines backward induction (BI) as the primary optimization technique with model predictive control (MPC) framework for real-time application. The article introduces a reduced-state control-oriented model of the SCR + ASC system, which is embedded into the BI algorithm to calculate optimal control actions within a finite horizon. Additionally, it is proposed an alternative approach for adapting the grid of model states within the BI algorithm, effectively reducing the computational cost. This adjustment enables the algorithm to operate in real-time with near-optimal results, as confirmed by experimental validation. Lastly, the study explores how different degrees of knowledge regarding system disturbances impact the strategy's performance, examining three distinct scenarios: constant prediction horizon, probabilistic description, and full knowledge of the prediction horizon. [ABSTRACT FROM AUTHOR]

Ammonia is a hydrogen-rich zero-carbon fuel, and is one of the most promising approaches to realize energy decarbonization in the fields of industry and transportation. Efficient operation and emissions control have been the primary obstacle to develop engines with high ammonia energy share. In this study, the combustion and emissions of an ammonia-fueled engine with diesel pilot ignition are investigated, and the target is to achieve ultra-high ammonia substitution with acceptable thermal efficiency. The ammonia energy share is first increased from 30% to 90% at an intermediate load, with a split diesel injection triggering ammonia combustion. It found that the increased ammonia energy share reduces the indicated thermal efficiency from 48.3% to 38.9% with high unburned ammonia emissions. The NOx emissions exhibit a turning point with increased ammonia substitution, which indicates that the NOx emissions transition from the thermal-dominated to the fuel-dominated regime. The diesel pilot injection strategy is then optimized, by advancing the main injection timing and changing the pre-injection amount and the interval between two injection events. Optimized diesel injection controls the ignition timing and combustion process, thereby improving thermal efficiency and emissions at high ammonia energy shares. An ultra-high ammonia energy share of 95% could be finally achieved, and the thermal efficiency is 40.2%. It is also noted that as engine load increases, engine thermal efficiency at an ammonia energy share of 80% could be elevated to 44.2%. [ABSTRACT FROM AUTHOR]

Coal-fired power plants (CFPPs) account for > 70% of electricity generation in India, but < 5% of facilities have installed technologies for sulfur dioxide (SO2) and nitrogen oxide (NOX) removal. Emissions of these pollutants lead to the formation of fine particulate matter (PM2.5) and an increased risk of premature mortality for exposed populations. Here, we use a nested version of the GEOS-Chem global chemical transport model (0.5° × 0.625° resolution) for India to estimate reductions in PM2.5 concentrations that could have been achieved by implementing existing emission control technologies like flue-gas desulfurization (FGD) and/or selective catalytic reduction (SCR). We quantify the associated burden of disease using the integrated exposure response (IER) and global exposure mortality model (GEMM) functions and compare the costs of premature mortality to those for FGD installation. Model simulations for 2010 suggest installation of FGD would have reduced mean annual PM2.5 concentrations across India by 8%, compared to 3% with SCR installation, and 11% with both FGD and SCR. A 7–28% reduction in PM2.5 was simulated for local communities closest to CFPPs (same model grid cell), leading to up to 17% reduction in annual premature mortality. Overall, more than 0.21–0.48 million premature deaths would have been avoided over a 10-year period if FGD had been implemented on all CFPPs, compared to 0.09–0.21 million with SCR and 0.22–0.72 million with both FGD and SCR. Benefits associated with such actions are approximately $18.1–$604 billion USD per year, which is equivalent to ~ 0.44 to 10% of India's GDP. These results suggest that monetary benefits from avoided premature mortality far outweigh the capital and operational costs of FGD and/or SCR installation of $19.5 billion and/or $32.8 billion per year, respectively. This information is essential because the high costs of installation and operation are often given as reasons for delaying installation and commissioning. We conclude that policy actions to control air pollution from CFPPs are economically justifiable. [ABSTRACT FROM AUTHOR]

This study addresses the pressing issue of urban air pollution impact, emphasizing the need for emissions control to ensure environmental equity. Focused on the Toluca Valley Metropolitan Area (TVMA), this research employs air quality modeling to examine ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide concentrations during three different periods in 2019. It quantitatively assesses the performance of a state-of-the-art air quality model while evaluating the efficacy of a No-Driving day mitigation measure program, similar to the one which is currently implemented in Mexico City. Using an updated national emissions inventory for 2016, this study highlights the model capability of representing ozone formation and shows that reducing mobile emissions of key pollutants contributes to lowering downwind surface ozone levels, albeit with a minimal local impact. The insights and tools from this work hold potential value for decision-making in the broader Megalopolis context, aligning with global efforts to comprehend and mitigate urban air pollution impacts. [ABSTRACT FROM AUTHOR]

Of major interest, especially in city environments, and increasingly inside vehicles or industrial plants, is the drive to reduce human exposure to nitrogen oxides (NOx). This trend has drawn increasing attention to filtration, which has developed remarkably owing to the capabilities of recently developed mathematical models and novel filter concepts. This paper reports on the study of the kinetic modelling of adsorption of nitrogen dioxide (NO2), collected from the tailpipe of a diesel engine, reacting to calcium nitrate salt (Ca(NO3)2) on a surface flow filter consisting of a coating of fine ground limestone or marble (CaCO3) in combination with micro-nanofibrillated cellulose (MNFC) acting as binder and humectant applied onto a multiply recycled newsprint substrate. The coating and substrate are both porous, but on different pore size scales, with the coating having significantly lower permeability. To maximise gas-coating contact, therefore, the coating deposition is pixelated, achieved by pin coating. An axially dispersed gaseous plug flow model (dispersion model) was used to simulate the transport within the coating pore network structure, following earlier flow modelling studies, and a kinetic reaction model was used to examine NO2 to NO3− conversion in correlation with experimental results. Modelling results indicate a 60.38% conversion of exposed NO2 gas to Ca(NO3)2 under the specific conditions applied, with an absolute relative error between the predicted and experimentally estimated value being 0.81%. The model additionally enabled a prediction of effects of changing parameters over a limited perturbation range, thus assisting in predicting filter element consumption, with attention given to the active component CaCO3 surface as a function of particle size in relation to the gas contact exchange, promoting the reaction over time. It is intended that the Ca(NO3)2 formed from the reaction can go on to be used as a value-added fertiliser, thus contributing to circular economy. [ABSTRACT FROM AUTHOR]

Abstract Background Climate change, driven by anthropogenic greenhouse gas emissions, is among the greatest threats to human health. The World Health Organisation (WHO), has led global efforts to respond to emerging public health threats including the control of hazardous substances such as tobacco, alcohol, lead and asbestos, with remarkable health gains. Body Despite WHO’s clear messaging on the enormous and growing health risks of climate change, greenhouse gases are not yet classified as hazardous substances, requiring control through a global strategy or framework. Additionally, WHO has not classified disease attributable to climate change as a result of the promulgation of these hazards as a Public Health Emergency of International Concern (PHEIC), despite the serious and preventable health risks it poses globally. Several historical precedents set the stage for WHO to declare excess greenhouse gases as health hazards, including the control of ozone-depleting substances and breast-milk substitutes where the public benefit of control exceeded the potential benefit of their promulgation. In addition, WHO’s undertaking within the International Health Regulations to protect global health, providing imperative to declare climate change a PHEIC, with Tedros Adhanom Ghebreyesus, director-general of WHO, declaring: “The climate crisis is a health crisis, fuelling outbreaks, contributing to higher rates of noncommunicable diseases, and threatening to overwhelm our health workforce and health infrastructure”. Importantly, the health sector, perhaps more than other sectors, has successfully overcome formidable, vested interests in combatting these threats to health. Conclusion It is thus imperative that WHO make full use of their credibility and influence to establish a global framework for the control of greenhouse gases through the declaration of excess greenhouse gas emissions as a hazardous substance, and declaring climate change a PHEIC. Who else is better placed to drive the considerable societal transformation needed to secure a liveable future?

This work investigates oxygen-storage capacity (OSC) changes during thermal degradation in modern three-way catalysts. Two experiments are performed using catalysts with different degradation degrees to evaluate OSC and reaction rates. The CO2 production test, where CO and O2 are supplied at a constant temperature, shows decreased CO2 production with more degraded catalysts and reduced purification. The CO2 production test is conducted using transient temperature increases, showing that the maximum CO2 production temperature increases with catalyst degradation. The results reveal an increase in activation energy in the oxygen desorption reaction caused by thermal degradation progresses and a decrease in OSC, resulting in temperature increases in the oxygen storage reaction. In the surface reaction and mass transport model considering the 30 elementary reactions, the predicted results are well-validated for CO2 production, enabling good oxygen storage predictions based on actual data. These results can be used to predict OSC by formulating the changes in active site density and activation energy due to degradation.

This study addresses the pressing issue of urban air pollution impact, emphasizing the need for emissions control to ensure environmental equity. Focused on the Toluca Valley Metropolitan Area (TVMA), this research employs air quality modeling to examine ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide concentrations during three different periods in 2019. It quantitatively assesses the performance of a state-of-the-art air quality model while evaluating the efficacy of a No-Driving day mitigation measure program, similar to the one which is currently implemented in Mexico City. Using an updated national emissions inventory for 2016, this study highlights the model capability of representing ozone formation and shows that reducing mobile emissions of key pollutants contributes to lowering downwind surface ozone levels, albeit with a minimal local impact. The insights and tools from this work hold potential value for decision-making in the broader Megalopolis context, aligning with global efforts to comprehend and mitigate urban air pollution impacts.

The waste incineration process is complex and variable, posing a great challenge for precise NOx emissions control based on selective non-catalytic reduction (SNCR). Complex changes in the operating conditions of waste incinerators have led to poor economics and low stability of NOx emissions control. Regarding SNCR denitrification technology, the combustion and denitrification processes are deeply coupled and interact with each other. The precise and economical control of NOx emissions could be achieved by optimizing combustion and denitrification parameters. Therefore, we propose a combustion (air flow) and denitrification (ammonia flow) parameters co-optimization method to achieve safe, economic, and environmentally friendly control of NOx emissions from waste incineration processes. This method encompasses the following three parts: (1) a sparse autoencoding bidirectional long and short-term memory neural network (SAE-(Bi-LSTM)) model is applied to predict combustion (main steam flow and average temperature) and emissions (NOx) status. (2) Opposition-based learning and population decision-making based on Metropolis acceptance criterion strategies are introduced into the particle swarm optimization (PSO) algorithm to enhance its global optimization-seeking capability under complex operating conditions. (3) Combined the SAE-(Bi-LSTM) models with an improved PSO algorithm to investigate the co-optimization of air flow and ammonia flow. In the co-optimization case with a control target set at 120 mg/m³, the average NOx emissions increased from 116.4 mg/m³ to 119.81 mg/m³. Simultaneously, there is a significant reduction in the standard deviation of fluctuations, decreasing from 9.39 % to 1.35 %, and ammonia consumption decreased by 4.43 %. In sum, the proposed co-optimization method can control NOx near the target value while saving ammonia consumption. • The SAE-(Bi-LSTM) model is proposed for combustion and emission modeling of MSWI processes. • An improved PSO algorithm for multi-parameter co-optimization is proposed. • The proposed co-optimization method can achieve accurate and economic control of NOx emissions. [ABSTRACT FROM AUTHOR]

We combined kinetics and in situ X-ray absorption spectroscopy to investigate redox pathways of N 2 O-selective catalytic reduction (SCR) by NH 3 and NO over Fe-exchanged Chabazite zeolites, a strategy to mitigate emissions of greenhouse gas N 2 O and toxic NO x from sources such as NH 3 engines. N 2 O-SCR occurs via FeII/FeIII redox cycles with N 2 O as the oxidant, and parallel reactions involving NO+NH 3 or NH 3 as reductants, where in situ XAS shows that most Fe ions are redox-active. NO co-reduces FeIII with NH 3 rather than oxidizing to NO 2. Net rates of N 2 O-SCR in gas mixtures containing NH 3 versus NO+NH 3 are both limited by FeII oxidation, resulting in similar apparent activation energies. In contrast, reduction pathway selectivity reflects the intrinsic kinetics of FeIII reduction steps with NO+NH 3 versus NH 3 , implying that reduction involving NO+NH 3 dominates at lower temperatures and higher NO pressures. This work provides fundamental insights into kinetics and mechanisms of N 2 O-SCR. [Display omitted] • Fe-zeolite for selective catalytic reduction of greenhouse gas nitrous oxide (N 2 O). • Deconvoluted contributions from reduction pathways with NO+NH 3 vs NH 3. • In situ XAS reveals FeII/FeIII ion redox cycle for N 2 O-SCR. • Net N 2 O-SCR rates are limited by FeII oxidation by N 2 O. • Selectivity instead reflects intrinsic FeIII reduction rates by NO+NH 3 vs NH 3. [ABSTRACT FROM AUTHOR]

Piperazine (PZ) activated 2-amino-2-methyl-1-propanol (AMP) is a high-performance solvent for CO 2 capture that has undergone long-term pilot test. This study explores its vapor amine emissions characteristics on Aspen Plus. It was found that the steady-state amine concentration in the water wash (WW) is a crucial factor affecting emissions, determined by the amine-to-water ratio obtained from flue gas and feed water. Under optimized conditions, vapor amine emissions were reduced from 1768 mg/Nm3 after the absorber to 1.46 mg/Nm3 after two WW sections. Two novel amine control methods were proposed based on the approach of lowering the amine concentration in the scrubbing liquid. Staged condensation of the stripper gas provides super low amine (0.06 wt%) feed water to the WW, further reducing vapor amine emissions by an order of magnitude. The Cooling Dry Bed (CDB) can achieve amine emission control effects comparable to two WW sections with only 20 % of the theoretically calculated interfacial area. This process has a lower total packing height and does not require liquid collection trays, significantly reducing the construction height and load of the column. [ABSTRACT FROM AUTHOR]

A methodology that allows the estimation of the stored oxygen (oxygen storage capacity (OSC)) along the TWC catalyst length by spatio-temporally resolving the O 2 profiles during rich to lean cycle conditions with the use of the Spaci-MS technique has been developed. As a case study, the effect of the presence of mixed cerium-zirconium oxide as oxygen storage material has been investigated. The oxygen storage capacity for the TWC containing Ce material was much higher than without. The study also explores the reaction pathways typical of TWC along the catalyst coordinates by spatio-temporally resolving O 2 , H 2 , CO, and NO, as well as the related products and intermediates providing important understanding on, for example, the water-gas shift reaction leading to H 2 production and how they develop differently depending on the OSM (oxygen storage material) in the catalyst. H 2 production occurs closer to the front of the TWC length in the case of the catalyst without Ce, and results in an earlier production of undesired NH 3 from NO reaction with H 2. However, more N 2 O has been observed for the catalyst with Ce, which suggests the catalyst composition could be optimised to minimize overall secondary emissions. [Display omitted] • Three-way catalysts for gasoline emissions control have been studied using SPACI-MS. • Axial conversion and concentrations were measured in the catalysts. • A methodology has been developed to measure oxygen storage capacity (OSC) using SPACI-MS. • Catalysts were studied with and without Ce to ascertain the role of OSC along the catalyst. • Oxygen breakthrough is significantly delayed when the Ce material is present. [ABSTRACT FROM AUTHOR]

This paper reviews the progress and effectiveness of Programs to Control Vehicle Emissions (PCVEs), comparing the experiences in the United States (US), European Union (EU), China, and Brazil. We present a timeline comparison of updates and differences in standards for light-duty vehicle (LDV) compliance. We then review the benefits of controlling LDV emissions on air quality, derived from previous relevant studies. Emission standards have been increasingly restricted in all evaluated PCVEs. However, some technical aspects such as dynamometer test cycles, re-testing structure of environmental protection agency, homogeneity of new and in-use vehicles inspection and maintenance, on-board diagnostics requirements are more consolidated in the US. Previous studies at different scales show the success of PCVEs in reducing vehicle emissions and air pollutant concentrations in the US, EU, China, and Brazil. Despite PCVEs has been achieving relative success, vehicular emissions are still a major threat to air quality around the world, especially in developing countries or ascending economies whose fleet grows dramatically. In places where the air quality standards recommended by the World Health Organization (WHO) are violated, it would be required the implementation of more stringent regulations with a well-designed, and homogeneous compliance policy over regional and national territories. This work contributes to clarifying the current challenges and successful experiences on regulating vehicular emissions worldwide. [ABSTRACT FROM AUTHOR]

The development of liquid ammonia spray combustion technology is expected to reduce the cost and size of gas turbines otherwise fueled with gaseous ammonia. However, successful studies on this topic are scarce due to the difficulty in flame stabilization. In this study, the flame stability and emissions control in liquid ammonia spray combustion is studied for the first time for input thermal power up to 230 kW using novel two-stage gas turbine combustors with and without slot film cooling at 0.25 MPa. The experiments were conducted in a micro gas turbine combustor test facility originally developed for gaseous ammonia combustion. The results show that the injection of liquid ammonia spray into a methane-air flame encouraged rapid cooling of the combustor liner head, enhancing flame blowoff. The blowoff limit based on ammonia fraction in the fuel showed a strong dependence on the combustor temperature, hence the combustor without slot film cooling extended the blowoff limit allowing the successful stabilization of pure liquid ammonia spray flame. Result of emissions analysis showed that two-stage rich-lean combustion is effective in controlling emissions from the flames, however, requires further enhancement of the flame in the primary combustion zone. An increase in combustor inlet temperature and a decrease in combustor wall heat loss, both of which enhanced the combustion of the liquid spray, resulted in a decrease in the emissions of NO, NO2, N2O, NH3, HCN and CO from liquid ammonia co-fired with methane. Conversely, pure liquid ammonia spray combustion resulted in higher emissions of NH3, NO and N2O than did the co-combustion with methane, encouraged by inhomogeneity in droplets distribution and larger heat transfer to the liquid droplets.

Mitigation of potentially hazardous and malodor compounds emitted from animal waste is needed to improve the sustainability of livestock agriculture. Bacteria control the generation of these compounds and also depend on the pH of manure. Influencing swine manure pH, especially on the liquid-air interface, may lead to a reduction of emission of odorous and hazardous compounds. The objective of this experiment was to test highly alkaline and porous (HAP) modified biochar with pH = 9.2 and red oak (RO) biochar with pH = 7.5 influence on swine manure pH acquired from the outdoor storage and deep pit storage under a barn. HAP and RO biochars were topically applied on the outdoor-stored (pH = 7.55), and pit (pH = 8.00) manures and spatial pH (every 1 mm of depth) were measured on days 0, 2, and 4. Results showed that HAP biochar increased outdoor-stored manure pH on day 4, particularly within the top 10 mm of depth, where pH ranged from 7.79 to 8.90, while in the case of RO pH ranged between 7.46 and 7.66, i.e., similar to control (7.57–7.64). Both biochars decreased pit-stored manure pH within the top 10 mm of depth (in comparison with the control pH of 8.36–8.47) to 8.19–8.30 (HAP), and 8.18–8.29 (RO) on day 4. However, differences were not considerable. The reason for the insignificant effect of biochars on pit manure was likely due to its higher buffer capacity in comparison with the outdoor-stored manure.

A model digital data processing platform is proposed based on “deep-learning” methodology that can be used to identify the emissions patterns from process plants with hybrid energy recovery and energy generation facilities. The non-invasive dynamic monitoring and correlation of particulate, VOCs and other greenhouse gas emissions from semi-batch and continuous process plants is demonstrated with use of neural encoding and pattern recognition using a multi-layer perceptron and multi-stack encoder configuration. A multi-layer environmental perceptron (MLEP) is developed based on the above analyses that aims to detect patterns of emission types, rates and concentrations as a function of variation of plant operational conditions and process variables. Four different task algorithms are constructed and are currently trained for use in (i) In-Plant Product Quality Control Domain and (ii) In-Plant Process Efficiency Target Control Domain. As a further consequence, environmental impact assessment is considered within the hazards and process safety frameworks that conventionally issue sanctions and penalize non-compliance with imposition of environmental levy scales rather than offering process improvement incentives. The latter is demonstrated to be possible by facilitating dynamic corrective action and hazard prevention using MLEP platforms should emission ceilings be frequently and/or periodically exceeded in 24/7 continuous plant operations. Potential applications of the MLEP (MLEP) are illustrated in the context of dynamic emissions control and abatement in hybrid energy process plants (HEPP) and combined power plants using process-integrated CO2 capture and storage schemes.

A source apportionment tool, ISAM (Integrated Source Apportionment Method), coupled with a regional air quality modeling system, RAMS-CMAQ (Regional Atmospheric Modeling System and Community Multiscale Air Quality), was applied to simulate the major aerosol components (sulfate, nitrate, ammonium, black carbon, organic carbon, dust, and sea salt) and investigate the impact of local and regional sources on the PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 μm) mass concentration over the North China Plain (NCP) in July 2016. The simulation results indicated that the high mass burden of PM2.5 mainly appeared in the south part of Hebei and west part of Shandong. The PM2.5 particles emitted from Beijing and Tianjin were just concentrated in the local area, but Hebei and Shandong were the dominant source over the NCP. Focusing on Beijing, the local contribution was just 20%–30% due to the emissions control strategies executed in recent years in Beijing. The pollutants derived from Hebei and Shandong were major contributors, providing more than 25% and 10% to the PM2.5 mass concentration in Beijing, respectively. Moreover, the surrounding regions showed larger contributions against the pollution background. The contribution percentage from Hebei and Shandong increased in both cases when the air quality became worse. Thus, it is suggested that comprehensive control strategies should be implemented based on coordinated control of emissions at the regional scale in Beijing, especially during pollution periods.

An A-site deficient perovskite material, namely La0.8FeO3, has been tested as a catalyst for the reduction of nitrogen oxide with carbon monoxide. The activity of the La0.8FeO3 has been compared with that of a low loaded supported Rh catalyst. Kinetic parameter fitting was performed on a range of model types to select the most suitable description of the two catalysts. The CO–NO reaction over the La0.8FeO3 is described by a Mars–van Krevelen mechanism, with active vacancy sites formed by reduction of the surface by carbon monoxide, and then reduction of nitrogen oxide at these vacancy sites. The Rh catalyst is best described by a Langmuir–Hinshelwood model. Once the best model was selected, kinetic parameters were derived that successfully describe the light-off behavior of the catalysts. Finally, the kinetic parameters were applied to a monolith reactor model, and sizing studies were carried out: under these simple reactor feeds, without the presence of other exhaust gas components, equivalent catalyst performance was achieved with double the volume of the La0.8FeO3 compared to the supported Rh catalyst. However, atomistic modelling studies show that other species typically present in an exhaust gas will strongly compete for the active vacancy surface sites, and this has also been seen in catalyst testing. Therefore, under real conditions the volume of catalyst required is likely to be much larger than that predicted for the simple system. [ABSTRACT FROM AUTHOR]

The short circuit of fresh air is a more and more extended strategy to deal with low-end torque issues, very common in small turbocharged and spark-ignited four-stroke engines. Therefore, from the author's point of view, it is interesting to check whether the after-treatment system can work properly under these conditions. In the present study, the effect of the fresh air short-circuit on engine emissions has been assessed through its impact on the wideband l sensor and the three-way catalyst behaviour, which are the key elements of the fuel-to-air ratio control strategy. In particular, the analysis of the sensor dynamic response shows that the l sensor overestimates the fuel-to-air ratio under short-circuit conditions. The sensor overestimation leads the actual fuel-to-air ratio out of the proper three-way catalyst window; in this sense, results show a non-negligible emissions increase, especially in terms of NOx. Regarding the impact on the threeway catalyst behaviour, the study shows how short-circuit pulses change the exhaust gas composition for a given fuel-toair ratio at catalyst inlet, which also contributes to a penalty in the three-way catalyst efficiency. [ABSTRACT FROM AUTHOR]

Methane–ammonia mixtures have potentials as low-carbon fuels for gas turbines, however significantly high fuel NOx production in their flames present challenges to their application. This study aims to provide deep insight into the physical and chemical processes involved in the formation and control of emissions from the combustion of CH 4 NH 3 –air with up to 30% ammonia by heat fraction in gas turbine combustors. Hence, laser diagnostics techniques such as Particle Image Velocimetry (PIV), and Planar Laser Induced Fluorescence (PLIF) imaging, in addition to Fourier Transform Infrared (FTIR) gas analysis were employed to study the flow field, flame structure and emissions characteristics of a micro gas turbine swirl combustor fuelled with CH 4 NH 3 –air mixtures. The control of emissions from the flames was further studied using Large Eddy Simulation (LES) of a model swirl combustor. The results show that NOx emissions from premixed CH 4 NH 3 –air in single-stage combustion were more than 5000 ppmv at equivalence ratios, Φ = 0.8–1.1, which is about twice more than the values already reported for NH 3 –air. Trends in NOx emissions correspond with the trends in OH radicals concentration in the combustor owing to the relevance of OH radicals in fuel NOx production. Emissions control leading to significantly low emissions such as 49 ppmv of NOx, 2 ppmv of CO and approximately zero N 2 O, HCN and NH 3 emissions with a 99.8% combustion efficiency was achieved using rich-lean combustion. An optimum Φ of the primary combustion zone for low NOx emission was identified, which varied from 1.30 to 1.35 depending on the ammonia fraction. For Φ richer (leaner) than the optimum Φ, NOx emission increased due to an increase in NOx production in the secondary (primary) combustion zone. Rich-lean combustion of CH 4 NH 3 –air emitted less NOx than that of NH 3 -air because the higher flame speed of CH 4 NH 3 –air mixtures ensured lower NOx production in the secondary combustion zone. [ABSTRACT FROM AUTHOR]

Black carbon (BC) emissions, resulting from the incomplete combustion of carbonaceous fuels, have been extensively linked to adverse impacts on air quality, climate change, and public health. Nevertheless, there is currently a lack of a comprehensive analysis that integrates activity-based BC emissions inventory and scenario analysis at the national/regional, sectoral, and sub-sectoral levels in Pakistan. This study aims to fill this gap by conducting a comprehensive evaluation of Pakistan's BC emissions inventory for 2021 along projecting emissions until 2050 under the reference emission scenario (RES) and the accelerated reduction scenario (ARS) using the GAINS modeling framework to assess the potential impact of mitigation measures. This study takes a unique approach by considering commonly overlooked sources of BC emissions, such as kerosene lighting, brick kilns, diesel generator sets, and natural gas flaring, which are not typically included in conventional analyses. National BC emissions in 2021 were estimated at 181 kt, with residential combustion being the major contributor, accounting for more than half (108 kt) of the total emissions. The transport, industry, waste, agriculture, power plants, and fuel conversion sectors contributed 26.1 kt, 20.1 kt, 10.7 kt, 8.9 kt, 6.0 kt, and 0.9 kt, respectively. We anticipate that the total BC emissions in Pakistan will reach 201 kt under the RES and 41 kt under the ARS scenario by the year 2050. The ARS achieves substantial BC reductions by the adoption of cleaner fuels, improved biomass stoves, end-of-pipe emission control technologies with higher removal efficiencies, and implementing a ban on the open burning of waste and crop residues. This study underscores the considerable potential for reducing BC emissions across various sectors in Pakistan over the next three decades. [Display omitted] • For 2021, Pakistan's BC emissions inventory showed total emissions at 181 kt. • The GAINS model is used to integrate new BC emissions source categories. • Modeling BC emissions mitigation in reference and accelerated reduction scenarios. • Advanced measures may cut three-quarters of BC emissions in the next 30 years. • Clean cooking and advanced measures will cut significant BC emissions in Pakistan. [ABSTRACT FROM AUTHOR]

This work investigates oxygen-storage capacity (OSC) changes during thermal degradation in modern three-way catalysts. Two experiments are performed using catalysts with different degradation degrees to evaluate OSC and reaction rates. The CO 2 production test, where CO and O 2 are supplied at a constant temperature, shows decreased CO 2 production with more degraded catalysts and reduced purification. The CO 2 production test is conducted using transient temperature increases, showing that the maximum CO 2 production temperature increases with catalyst degradation. The results reveal an increase in activation energy in the oxygen desorption reaction caused by thermal degradation progresses and a decrease in OSC, resulting in temperature increases in the oxygen storage reaction. In the surface reaction and mass transport model considering the 30 elementary reactions, the predicted results are well-validated for CO 2 production, enabling good oxygen storage predictions based on actual data. These results can be used to predict OSC by formulating the changes in active site density and activation energy due to degradation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

The materials presented at the Fifth Russian Coking Conference (Moscow, October 10–11, 2019) are reviewed. [ABSTRACT FROM AUTHOR]

Despite the potential benefits of the Homogenous Charge Compression Ignition (HCCI) engines, controlling the combustion phasing and emissions are the main obstacles in its development but, in conventional engines the load demand is simply controlled by accelerator. The aim of present work is developing a HCCI engine controller which controls its main parameter similar to conventional engine: controlling the combustion phasing based on load demand. In the present study, A Multi-Input Multi-Output (MIMO) controller has been designed and validated which is used to control HCCI engine main parameters such as: optimum combustion phasing, engine load and minimum emissions. Similar to conventional IC engine the controller is capable of tracking all desired set-points solely by means of load demand as the only reference trajectory. A physic-based control model together with application of Artificial Neural Networks (ANN) is developed to predict the optimum combustion phasing with minimum emissions based on load demand. The results of proposed model are validated with the experimental data for steady state and transient cases. The optimal CA50 is selected based on minimizing the emissions using a multi-zone kinetic coupled with a genetic algorithm. The developed controller performance has been tested thoroughly to evaluate the tracking and disturbance rejection capabilities. Results show that it is capable of rejecting the disturbances for fix engine loads. The controller is quick to reject the disturbances within 3–5 engine cycles, while deviations within 0.04 bar, 0.5CAD and 0.03 for IMEP, CA50 and emissions respectively. • We presented a brand new MIMO controller to control HCCI engine main parameters. • The controller is capable of tracking all desired set-points solely by engine load demand. • Similar to IC engines the controller requires only IMEP for optimal CA50 and Min. NCHC. • The model-based controller dictates HCCI engine to operate only at optimal conditions. • The controller is tuned by using a thermo-kinetic model rather using test data. [ABSTRACT FROM AUTHOR]

Abstract Technologies for controlling gaseous emissions of livestock is of interest to producers, the public, and regulatory agencies. In our previous lab-scale study, the use of a photocatalytic coating on surfaces subjected to black ultraviolet light reduced emissions of key odorant compounds relevant to the livestock industry. Thus, an on-farm pilot-scale experiment was conducted at a commercial swine barn to evaluate a photocatalytic coating on surfaces subjected to ultraviolet light under field conditions. A flow-through reactor was constructed with a TiO 2 -based photocatalytic coating on the interior surfaces and black ultraviolet light fixtures. The reactor was deployed in a room downstream of the entire swine barn exhaust. Gas samples were collected from three sampling ports in the reactor, one at the inlet (control), the midpoint (half treatment) and the outlet (treatment). Compared to the control, significant reductions in emissions were observed for p -cresol (22%), odor (16%) and nitrous oxide (9%). A significant increase in carbon dioxide (3%) was also measured. Results show that the TiO 2 -based photocatalytic coating and black UV light are effective in mitigating odor, a key VOC responsible for downwind swine odor, and one important greenhouse effect gas when subjected to swine barn exhaust. Graphical abstract Image 106 Highlights • UV light and photocatalyst tested on farm to mitigate gaseous emissions. • Treatment reduced p -cresol emissions 22%. • Treatment reduced odor emissions 16%. • Treatment reduced N 2 O emissions 9%. • No significant change to CH 4 emissions was observed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Review of current HC trap (HCT) and passive NOx adsorber (PNA) technologies. • Zeolites are important materials in HCTs and PNAs for automotive applications. • HCTs and PNAs need to be durable at high temperatures for real-world applications. • Regeneration of adsorption capacity during multiple cold starts is crucial. Abstract The modern three-way catalyst (TWC) is very effective for treating the hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NOx) from stoichiometric gasoline engines once the TWC has achieved its minimum operating temperature (e.g., 250 to 400 °C, depending on the gas species). Likewise, the diesel oxidation catalyst (DOC), selective catalytic reduction (SCR) catalyst with urea injection, and the diesel particulate filter (DPF) are effective for treating the HCs, CO, NOx, and particulate matter (PM) emissions from diesel engines once the catalysts are warmed up, although this can require a significant length of time (e.g., 1 to 3 min) because of the relatively low exhaust temperatures from diesel engines. For both types of engines, excess fueling is often used to accelerate the heating of the catalyst system after a cold start, although this decreases the fuel economy of the vehicle. Even with excess fueling, a high portion (up to 80%) of the total vehicle emissions is emitted during the cold start period (i.e., the period before the catalysts are functional). To treat the HC emissions during this cold start period, one approach is to employ a HC trap (HCT) that can adsorb the HC emissions at low temperatures and then oxidize the stored HCs to carbon dioxide (CO 2) and water (H 2 O) at higher temperatures. To treat the NOx emissions during the cold start period, a passive NOx adsorber (PNA) can adsorb the NOx at low temperatures. For stoichiometric gasoline applications, the PNA can then reduce the stored NOx to nitrogen (N 2) at higher temperatures. On diesel engines, the PNA can release the stored NOx back into the exhaust once the downstream urea/SCR system is operational. Some adsorber technologies have the capability of adsorbing HCs and NOx simultaneously. In this review, the HC trapping and passive NOx adsorbing technologies will be discussed in separate sections. This review will describe how the current trapping technologies can be applied in vehicle exhaust systems, the material properties required for efficient HCTs and PNAs, and the exhaust conditions that can inhibit/enhance their trapping properties. First, the performance of HCTs will be discussed in terms of their physical properties (e.g., pore size, acidity, presence of metal ions) and the trapping conditions (e.g., storage temperature, space velocity, and the presence of other exhaust species such as H 2 O and CO 2). This will be followed by in-depth coverage of the reactions occurring during HC desorption. The second part of this review will focus on the composition of various PNA formulations, the effects of the trapping conditions (e.g., temperature, space velocity, the presence of other exhaust species such as CO 2 , H 2 O, CO, and C 2 H 4), and the effects of sulfur poisoning on their trapping performance. The effect of hydrothermal aging and the regenerability of HCTs and PNAs will also be discussed. A significant amount of literature has emerged recently regarding HCTs and PNAs; this review is primarily focused on summarizing this literature and reconciling the differences presented. [ABSTRACT FROM AUTHOR]

Automotive exhaust catalysts with NOx and/or oxygen storage functionalities remain one of the key contributors to the high environmental performance of internal combustion engines. However, the exposure of catalysts to sulfur during real-world operation reduces progressively their NOx abatement performance. The aim of this paper is to demonstrate the capability of advanced physico-chemical models to simulate the competitive storage of sulfur and NOx on the catalyst surface and predict the various interactions, in particular the negative effect of sulfur on NOx storage and reduction efficiency. It is clarified that predicting the sulfur storage on sites where NOx can be adsorbed and on sites which are not related to NOx storage allows the accurate simulation of the NOx storage efficiency over sulfur loading. Moreover, the spatial interplay of the formed nitrites, nitrates and sulfates during the sulfation of the catalyst is highlighted. The model is validated in steady state conditions using synthetic gas bench tests and ultimately in transient conditions using actual driving cycles data derived from engine test bench measurements. [ABSTRACT FROM AUTHOR]

In this work, a series of model NOX storage catalysts with different Pt and Ba loadings (in the range 0-2 wt% and 0-20 wt%, respectively) have been studied for NOX storage and desorption. The samples have been characterised by in-situ DRIFTS to identify the nature of the stored species and by EXAFS to gather information about the Pt particle size. A correlation between the average Pt particle size and the Pt/Ba ratio has been found. A simple kinetic model for NOX storage and thermal desorption has been developed, which can reasonably capture the experimental results over a wide range of conditions. The fitting parameters have been optimised independently for each of the samples and have been found to be dependent on the catalyst's structural properties (average Pt particle size, total Pt perimeter and Ba loading). The so found correlations have been introduced in the model, which can now be used to simulate the behaviour of catalysts with different Pt and Ba loadings as well as to optimise the catalyst composition for different applications. [ABSTRACT FROM AUTHOR]

This work presents a simulation approach to the design and economic evaluation of fuel oil hydrotreating processes for the control of SO2 and NOx emission in an Iranian steam power plant. The percent of fuel oil desulphurization was estimated from the SO2 emissions standards for power plants. Based on two different scenarios according to (I) European and (II) Iranian standards, the design and simulation of hydrodesulphurization reactors, separation, heat recovery, and amine gas sweetening sections were performed and an economic assessment of the plant was investigated for each scenario. The results indicated the following: the cost price of each barrel of low sulfur fuel oil produced in such plants was estimated at 4.24 US$ for scenario (I) and 3.17 US$ for scenario (II); the levelized cost of desulfurization in power production was estimated at 0.618 c/kWh for (I) and 0.463 c/kWh for (II); and the social cost savings of replacing every barrel of low sulfur fuel oil instead of one barrel of high sulfur fuel oil were estimated at 26.7 US$ for (I) and 13.6 US$ (II).

Gas-phase advanced oxidation (GPAO) is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8) and reduced sulfur compounds (e.g. H2S and CH3SH), removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

Graphical abstract Abstract Environmental friendly fuels have increasing demand in the field of automotive industry. Hybridizing with biodiesel and addition of nanoparticles are two evident techniques to improve the performance and to control the hazardous emissions. Combination of appropriate weight fractions of nanoparticles, biodiesel, and diesel further optimize the engine outcomes. The present work aims at investigating the effect of zinc oxide (ZnO) nanoparticles suspensions in diesel and Mahua biodiesel blended fuel on single cylinder diesel engine performance characteristics. Experimental tests are performed with neat diesel fuel, biodiesel blends and ZnO added biodiesel blends. The results indicate that ZnO particulate addition yields favorable performance and emission control of the engine. A generalized regression neural network (GRNN) is implemented for predicting the performance and emissions of the engine at various operating conditions based on the experimental results. The neural network predictions are corroborated with the experimental results and are found in good agreement. A classical differential evolution algorithm (DEA) is further used on the network model to find out optimal combination of nanoparticles, biodiesel and diesel and proven through experimental validation. [ABSTRACT FROM AUTHOR]

Charge air cooling is the typical technique to reduce temperature of the engine intake air, increasing air density and improving cylinder filling and engine volumetric efficiency in present turbocharged diesel engines. Usually, charge air is cooled by environmental air that crosses a heat exchanger placed in front of the vehicle: its cooling capacity is related to the vehicle speed and other constraints (presence of the main radiator). This leads to an intake air temperature from 30 to 80 °C, depending on engine load, external air conditions and vehicle speed again. If the intake air was more cooled down, the engine volumetric efficiency would be further increased. This can only be done by the use of a dedicated cooling fluid, operating at lower temperature with respect to external air. In this paper, therefore, an evaporator, mounted in parallel with the one of the refrigeration unit used for cabin cooling, was placed on the intake line of a turbocharged diesel engine (F1C IVECO engine), tested on a high speed dynamometer bench: the air refrigeration unit is also composed by a compressor, a condenser and a thermostatic expansion valve. The effects of the undercooling of the charge air have been experimental assessed in terms of fuel consumption and regulated emission reduction, evaluated on the most common engine operating points. Mechanical power demand of the compressor has obviously taken into account in order to assess overall benefits. Achieved net fuel consumption is in the order of 1% at fixed conditions operating the engine as a light duty type, when the intake air sub-cooling is turned on. A benefit on the regulated emissions has been observed (Nitrogen Oxides, Soot) regardless of the setup of the engine combustion processes (injection time, fuel distribution for each injection, Exhaust Gas Recirculated rate). Unburned hydrocarbon and Carbon monoxide behavior, on the other hand, deserves some more attention and call for the re-calibration of the previously cited combustion control parameters. [ABSTRACT FROM AUTHOR]

The carbon tax is a cost‐efficient scheme to curb emissions, and it has been implemented in Australia, British Columbia, and other places worldwide. We aim to analyze its effect on dynamic pricing in a supply chain with multiple suppliers and one manufacturer. The profit‐maximizing manufacturer makes final products using raw materials from suppliers with heterogeneous prices and emission rates. A two‐stage game model is built over an infinite time horizon for this issue. In the first stage, suppliers face price‐dependent demand to set their prices and production rates under the constraint of inventory capacity. Then, in response to the carbon tax scheme, the manufacturer evaluates the procurement prices and emission rates of suppliers to control its emission volumes and sets the sales price of its product. This article predominately focuses on the optimal pricing strategies in a decentralized supply chain. The open‐loop equilibrium and Markovian Nash equilibrium for the dynamic pricing game models of both suppliers and the manufacturer are derived, respectively. The equilibrium prices of suppliers and the manufacturer can be solved based on both irreversible actions and real‐time states. These two types of equilibria can be regarded as the solutions of two different models in specific situations. To analyze the effect of sourcing diversity on pricing strategies and emissions control for the manufacturer, the more general equilibrium price for the manufacturer in an n‐suppliers oligopoly is studied. Numerical examples are presented to illustrate the equilibrium and its monotonicity with various parameter settings. [ABSTRACT FROM AUTHOR]

The latest IMO regulatory requirements concerning the control of toxic gas emissions from ships have sparked interest in whether ships are adequately equipped to operate safely in adverse weather conditions when compliance is achieved simply by the reduction of power. This paper deals with the analysis of navigational accidents (collision, grounding, and contact accidents) that occurred in adverse weather conditions and may have been related to the lack of sufficient powering and manoeuvrability. The analysis aims to potentially assist the IMO regulatory work in setting rational margins of minimum powering of ships for safely operating in adverse weather conditions. [ABSTRACT FROM AUTHOR]

The objective of this study was to test the potential for NO x emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A commercially available car was selected and was first measured in its original configuration according to RDE on the road and an initial conformity factor (CF) of 5.4 was determined. Subsequent engine calibration and installation of a Selective Catalytic Reduction (SCR) device were conducted and tested on a fully transient engine dyno setup, which precisely reproduced the engine operation under the on-road RDE test. The NO x reduction achieved with those upgrades was 90%, leading to a CF of 0.53, with no CO 2 or fuel consumption penalty. These findings demonstrate that diesel vehicles can reach low NO x levels under real world driving conditions, when well-designed modern exhaust aftertreatment components are installed and properly calibrated. [ABSTRACT FROM AUTHOR]

After-treatment systems (ATS) in vehicle powertrains are developed to achieve maximum pollutant abatement efficiency under design operating conditions. However, anomalies in the ATS may appear during real operation, such as reducing agent supply failure and catalyst ageing. As in the case of an ATS composed of a selective catalytic reduction (SCR) system plus an ammonia slip catalyst (ASC), injection failure leads to insufficient ammonia levels to reduce nitrogen oxide (NO x), and ageing decreases the ammonia storage capacity and NO x conversion efficiency, these drawbacks drive both pollutants to levels above those expected and allowed by governmental regulations. To address this problem, a novel methodology was proposed that simultaneously estimates the operational state of the ATS in terms of ammonia injection failure and ASC catalyst ageing. The approach through control-oriented models based on an artificial neural network (ANN) and sensor signal analysis (SSA), as well as an extended Kalman filter (EKF) observer, compares the current emission levels estimated by the observer in a two-dimensional probabilistic plan and a variable time-window, with those expected if the ATS were operating under normal conditions. The proposed methodology was evaluated in real driving cycles with the ATS subjected to several undesired operating conditions. As a result, the model was able to accurately estimate the levels of ammonia injection failure and catalyst ageing state. Therefore, enabling the control system to modify the ammonia injection strategy to achieve desired levels of NO x and NH 3 emissions. • Assessment of the effect of SCR ammonia injection failure on exhaust emissions. • Impact of ASC catalyst ageing on the NOx and NH3 emissions level. • Model-based fault detection and diagnosis of SCR+ASC in real driving conditions. • Probabilistic simultaneous detection of ammonia injection fault and catalyst ageing. [ABSTRACT FROM AUTHOR]