Reduce NOx Emissions Research Articles

Geothermal Condition Investigation and Resource Potential Evaluation of Shallow Geothermal Energy in the Yinchuan Area, Ningxia, China

Shallow geothermal energy (SGE) is a promising green and sustainable energy source, gaining prominence in light of the dual-carbon target. This study investigated the SGE resources in the Yinchuan area. Suitability zones and the potential of SGE resources were determined based on the comprehensive analysis about thermophysical parameters, hydrogeological conditions, and geological environment. Our findings revealed that the effective thermal conductivity in the Yinchuan area surpasses those of other cities, indicating significant potential for SGE. The thermostat layer depth ranges from 40 to 60 m, with a geothermal gradient between 0.81 and 6.19 °C/100 m. Regions with poor adaptability for a borehole heat exchanger (BHE) are mainly distributed in the western and southern parts of the Yinchuan area, whereas moderately and highly adaptable areas are primarily located in the central and eastern areas, respectively. The total geothermal resource of the BHE in the Yinchuan area amounts to 1.07 × 108 GJ/a, generating significant economic benefits of 1.07 × 109 CNY/a and saving 1.09 × 106 t/a of standard coal annually. This initiative leads to significant reductions in CO2, SO2, and NOx emissions by 2.61 × 106 t/a, 1.86 × 104 t/a, and 6.57 × 103 t/a, respectively. Additionally, it results in potential savings of 0.309 × 109 CNY/a in environmental treatment costs. The methods and models used in this study have potential for similar geothermal surveys in arid and cold regions. The results also contribute essential insights for policy formulation and sustainable development strategies related to shallow geothermal resources in the Yinchuan area.

THE EFFECTS OF NANOADDITIVES ON A SINGLE CYLINDER DIESEL ENGINE USING PROSOPIS JULIFLORA BIODIESEL

This study looks at how a Prosopis Juliflora methyl ester-powered one-cylinder direct injection diesel engine burns, works, and gives off emissions when titanium nanoadditives are added at two different concentrations: 25 ppm and 50 ppm. The test engine should be run at 1500 rpm continuously with 17.5 compression and 23-degree BTDC timing. A magnetic agitator and an ultrasonic converter are used to mix aluminium nano-additive materials. Due to the high surface-to-area-volume ratio of alumina particles with smaller-scale alumina nanometrics, combustion is boosted and emissions are minimised, according to experimental studies. Furthermore, the alumina blend greatly improved brake thermal efficiency, lowering fuel consumption by 6.56 percent initially and 7.37 percent thereafter. In terms of combustion efficiency, this leads to a modest reduction in NOx, CO, HC, and smoke emissions.

Strategic optimization of dual-fuel diesel/gas engines by numerical approach for environmental and economic benefits

The study introduces a framework for optimizing eco-friendly dual-fuel engines, combining CFD and ANN, to reduce carbon emissions and improve sustainable transportation.We achieved optimal performance with a 52–65 % NG substitution ratio. SOI timing had a big effect on NOx emissions; later injection decreased NOx formation because it made the mixture more homogeneous. We developed a radial basis function neural network model to predict engine performance and emissions with 99 % accuracy. The study examines the effect of fuel droplet spraying on cylinder walls on engine performance and emissions, utilizing response surface methodology to create engine maps. Numerical experiments revealed that a lowered natural gas replacement ratio of less than 50 % resulted in decreased flame propagation and the attainment of a burn mixture mode. The decrease in flame propagation speed during CA10 led to a fivefold increase in CO emissions. As the NG substitution ratio exceeded 50 %, the air/fuel ratio neared equilibrium, resulting in a reduction in NOx emissions and in-cylinder combustion temperature. Nevertheless, the highest RoHR level decreased by 25 %. The downward trend proceeded until the natural gas substitution ratio reached to 90 %. The TOPSIS method was utilized to identify optimal operating conditions for DFDI engines, offering valuable insights for efficiency and emissions reduction.

Experimental and numerical investigations on NH3/H2 fueled combustion in the combustor with block for improved micro power generation

To advance the application of zero-carbon fuels in micro-combustion, enhance energy conversion, and reduce NOx emissions in NH3/H2-fueled micro-power generators, a micro-combustor with an insertion block is proposed and tested under various chamber configurations and operational conditions. Experimental and numerical tests are conducted in micro-combustors with varied block settings, burner dimensions, NH3 blended ratios (mN), and fuel flow rates (Vf). The results indicate that mN significantly impacts the generation and consumption of H, O, and OH radicals, as well as NO, affecting flame regime and heat transfer. Specifically, adding 5∼15% NH3 improves the operating performance of the burner, with the highest mean temperature achieved in combustor #24C3-0.4 at mN=15%. Block insertion alters flame characteristics and enhances gas-wall heat transfer, the combustor with thinner blocks at higher mN and thicker blocks at lower mN contributes to better thermal performance. Furthermore, combustors with thinner blocks exhibit lower NO emissions. The working performance of the micro-thermophotovoltaic system can be enhanced by selecting the appropriate burner length with block thickness W=0.4 mm and position Lb=7 mm based on Vf. The maximum electrical power of 3.7 W is achieved with a burner length of 28 mm for the system using InGaAsSb cells at Vf=1200 mL/min.

Quantifying consumption-based environmental productivity from “Energy-Environment Footprints”

Addressing the challenge of climate change through accounting is crucial for sustainable development, which is influenced by factors such as productivity growth, technical change, efficiency change, and environmental accounting. However, previous studies have predominantly focused on production-based growth accounting, neglecting the significant impact of consumption on growth accounting levels. In response, this study introduces a synthetic index termed as consumption-based environmental productivity. This innovative index utilizes the Luenberger Productivity Index (LPI) and the Logarithmic Mean Divisia Index (LMDI) models, relying on a Multi-regional Input-output (MRIO) footprint instead of direct emissions. Our empirical research found that from 2000 to 2014, certain economies bore a considerable portion of undesirable emissions imported from abroad. This supports the argument that the footprint approach is a valid alternative to direct emissions assessments. Further analysis revealed an overall growth trend in environmental productivity (EP) of 0.79%. Efficiency change (EC) contributed negatively (-0.35%), while technical progress (TP) positively influenced EP by 1.14%. Additionally, our study points out that reductions in NOX and SO2 emissions were primarily due to energy intensity improvements. Conversely, CO2 emissions were driven by individual production factors and economic growth. These results underscore that establishing clear responsibility for emissions is the foundational step in implementing emission reduction policies in an equitable manner. Concurrently, it is crucial to improve the efficiency of energy consumption and mitigate undesirable emissions to significantly enhance productivity, especially for developing economies, policies should prioritize the development of energy cleanliness and energy efficiency. Furthermore, it is imperative for all economies to refrain from pursuing unnecessary economic growth that could lead to excessive emissions.

Vacuum-dried precursor to combustion synthesis CuO- based oxygen carriers with less NOx pollutant and its cyclic performance in chemical looping combustion

Chemical-looping combustion (CLC) technology is considered a promising combustion method with inherent CO2 capture. In this study, the sol-gel method and combustion synthesis were employed to produce precursor materials (P) of CuO-based oxygen carriers (OCs). The effects of vacuum drying conditions on both NOx emissions from precursor combustion and oxygen carrier cycle reaction characteristics were investigated. Vacuum-dried precursors emitted less NOx during the precursor calcination process. At a heating rate of 1 °C/min, the vacuum-dried precursors exhibited an average reduction of 24.13 % in NOx emissions compared with those prepared through atmospheric pressure drying. An increased amount of Cu2(OH)3NO3 in the precursor results in greater heat release during the self-propagating high-temperature combustion synthesis used to synthesize the oxygen carrier. Furthermore, the complete combustion of the nitrogen-containing precursor leads to a reduction in the emission of NOx. CuO-based OCs exhibited stable redox reactions over 10 cycles. Vacuum drying enhanced CH4 conversion and CO2 yield of OC1 by 14.04 % and 13.21 %, respectively, compared to atmospheric pressure drying. The results indicate that the CuO-based OCs obtained through vacuum-dried significantly enhance redox properties. This study shows that vacuum-dried reduces NOx emissions from nitrogen precursors and enhances the cyclic efficiency of OCs from precursor combustion.

Mechanism of preheating modification on NOx emission reduction during peak shaving of different coal ranks

During peak shaving operations, coal-fired power plants are often associated with unstable combustion and increased NOx emissions. In this study, a preheated modification device for pulverized coal was employed to reduce NOx emissions during peak shaving. The conversion characteristics of char-N, tar-N and NOx precursors (NH3 and HCN) have been extensively elucidated. Moreover, the mechanism for NOx reduction during preheating combustion has improved. The results indicate that in high-rank coals, char-N is the dominant nitrogen-containing component (>50 %), and the relatively high thermal stability limits its reduction to N2. The release of preheated tar mainly occurs in low-rank coals with loads less than 40 %, corresponding to temperatures of approximately 660 °C–725 °C. Moreover, the main NOx precursors in low-/high-rank coals are NH3 and HCN, respectively. After preheating, the fuel is activated, and 75 %–96 % of the fuel nitrogen can be removed because of the pre-denitrification mechanism. The NOx emissions can be maintained within 335 mg/m3 (6 % O2) over the load range of 25 %–110 %. However, N2O increases rapidly at loads below 60 % (<980 °C). Furthermore, the conversion of fuel-N to NOx increases and then decreases with increasing load, with inflection points at 80 % and 40 % loads for high- and low-rank coals, respectively.

Spatio-temporal variability and trends of air pollutants in the Metropolitan Area of Curitiba

Monitoring air pollutants over time is essential for identifying and addressing trends, which may help improve air quality management and safeguard public health. This study investigates the spatio-temporal variability of air quality in the Metropolitan Area of Curitiba (MAC), Brazil, focusing on six pollutants (SO2, NO2, NOx, O3, CO, and PM10) measured at eight monitoring stations from 2003 to 2017. We conducted statistical analyses, including diurnal cycles, seasonal variability, spatio-temporal correlations, conditional bivariate probability functions, Theil-Sen trend analysis, and comparison with national quality standards (NAQS) and World Health Organization (WHO) guidelines. The analyses revealed large variations in pollutant concentrations across the study area. For instance, stations strongly impacted by industrial emissions presented the highest mean annual SO2 (20–28 μg/m3) and PM10 (32–34 μg/m3) concentrations, while those mostly impacted by traffic showed elevated NO2 (31–39 μg/m3), NOx (63–86 μg/m3) and CO (0.6–0.8 mg/m3) concentrations. The two residential stations recorded the highest O3 concentrations (annual mean of 30–32 μg/m3). Seasonal and diurnal patterns varied by pollutant, with winter experiencing higher concentrations and O3 peaking in spring. SO2 concentrations presented no clear seasonal or diurnal cycle patterns, and showed the highest spatial variability. Significant decreasing annual trends were observed for SO2 (−5.9%), NO2 (−2.6%), NOx (−2.6%), CO (−5.4%), and PM10 (−3.7%), which suggests the success of emission reduction programs implemented in the road transportation and industrial sectors. However, O3 concentrations increased at most stations (+3.3%/yr), likely due to reduced NOx emissions, increased emissions of volatile organic compounds from on-road transport biofuels, and regional O3 transport. Although exceedances of NAQS decreased over time, concentrations of most pollutants remained above WHO guidelines, except for CO. These results highlight the importance of targeted emission control strategies for both industrial and vehicular sources to improve local air quality and inform future policy decisions.

Addressing the challenge of ammonia slip and nitrous oxide emissions from zero-carbon fuelled engines through catalytic aftertreatment solutions

Addressing climate change demands, energy security and resilience has necessitated replacing conventional fossil-based fuels with zero and carbon-neutral fuels/energy carriers. The most immediate solution is the partial and progressive substitution of conventional fuels in transportation. The effects of partially substituting gasoline with ammonia/hydrogen (NH3/H2) mixtures in a spark ignition (SI) engine are investigated in this paper. The utilization of NH3/H2 mixtures is a promising avenue of research since they can be produced from on-board NH3 reforming, utilising heat energy that is recovered from hot exhaust gases. Experimental results indicate that adding NH3/H2 enabled stable engine operation at lean conditions (λ = 1.4), resulting in reduced carbon-based emissions due to the non-carbon nature of NH3/H2. Utilising an integrated approach that combined a hemispherical flame geometry model with a thermodynamic model, has revealed that the introduction of NH3/H2 significantly enhanced the combustion speed during the initial phase and further improved combustion efficiency. However, nitrogen-based emissions such as NO and NO2 increased. This work also assessed the performance of a conventional three-way catalyst (TWC) and a double-function ammonia slip catalyst (ASC) in mitigating emissions. The TWC effectively controlled carbon-based emissions and NO under stoichiometric conditions but exhibited reduced efficiency under lean conditions, especially with NH3 present. The ASC demonstrated high NH3 conversion efficiency even at low temperatures, making it suitable for engine start-up and warm-up phases. Under steady-state conditions with artificially increased NH3/NOX ratios, a significant reduction in NOx emission was achieved with the ASC. However, high NH3/NOX ratios increased nitrous oxide (N2O) formation and NH3 slip.

Pollutant emission during pyrolysis of waste wind turbine blades: Nitrogen-containing components and polycyclic aromatic hydrocarbons

Serious attention was lacked for various pollutants formed in both gas and tar phase during pyrolysis recycling of waste wind turbine blades (WWTB), especially for components of carcinogenic bisphenol A (BPA) and potentially toxic polycyclic aromatic hydrocarbons (PAHs) in tar. Pyrolysis temperature within 400–600 °C would significantly impact pollutant formations. Additionally, CO2 had a potential to mitigate pollutants emission as an economic alternative for N2. This article investigated the influence of these factors on nitrogenous and PAHs components during WWTB pyrolysis through fixed bed and thermogravimetric experiments. The results showed that NO2 was dominated in nitrogen containing pollutants and was related to the evolution of pyrrole nitrogen oxides. It was found 550 °C as a turning temperature, at which the polycondensation reaction appeared significantly. This resulted in a markedly increase for toxic N-PAHs in tar. At this temperature, CO2 could be used to mitigate nitrogen pollutants. 25% CO2 reduced NOX emission about 26% and selectively promoted NH3 releasing to over 4.3 times and depressed HCN generating to 0.6 times. Moreover, the primary depolymerization product of organic pact in WWTB was BPA. Increasing residence time, temperature and CO2 concentration were beneficial for converting hazardous BPA to high valued P-Isopropenylphenol (IPP). The value of IPP:BPA could increase to over 2 in this experiment. It was aimed to provide not only an evaluation for the yield and migration of pollutants, but also an cleaner recycling solution through graded pyrolysis WWTB to mitigate pollution and maximize the value of by-products.

Waste collection route optimisation for the second waste-to-energy plant in Budapest

The city of Budapest produces approximately 680–700 000 tonnes of municipal solid waste every year, of which <2/3 is being recycled or used for energetic purposes, the rest ends up in a landfill. To combat this environmental and logistical problem the installation of a second waste incineration plant has been proposed in the south of the city. The only cost associated with fuel consumption in the case of waste to energy powerplants (WtE plants) is the transport cost, as the city council provides economic support for waste disposal. Since the transportation has a huge influence on the cost of opertation, logistical optimisation of the transport routes promises a direct impact on cost savings. In this study the logistical optimisation of the Southern Budapest area was carried out using image processing and logic based algorithm programming. As a result the optimal transport of 230 000 tonnes of municipal solid waste (MSW) was solved resulting in a 4 835.2 km monthly travel distance reduction.This value can be translated to 7 823 €/month cost, 9 459.6 kg/month CO2 and 45.3 kg/month NOx emissions reduction in the urban areas.

Numerical Investigation of CO and NO Production From Premixed Hydrogen/Methane Fuel Blends

Abstract There is significant interest in utilizing hydrogen as an energy carrier in a net-zero carbon energy economy. A variety of fundamental and practical issues associated with premixed hydrogen/methane combustion must be addressed, particularly flame flashback, combustion instabilities, and NOx emissions. Significantly less attention has been given to CO emissions from hydrogen blending. However, recent H2 blending engine tests have clearly noted major reductions in CO emissions, reductions which substantially exceed what would be expected based upon C atom mass balances in the fuel. Moreover, NOx, CO, and combustor operability always tradeoff with each other, and so, for example, these CO reductions can also enable operational or design modifications to reduce NOx emissions and/or wider operability windows. This paper addresses H2 blending effects on CO emissions, addressing both the direct influences on CO emissions, as well as how it influences NOx–CO tradeoffs. The paper presents computations that differentiate between the kinetic and equilibrium effects of H2 blending, as well as how H2 blending can lead to reductions in both NOx and CO by moving the Pareto front downward. Finally, this work suggests that H2 blending, in addition to its CO2 reductions, can also increase plant operational flexibility and so provide additional value propositions to an evolving electricity market.

The Effect of Bioalcohol Additives on Biofuel Diesel Engines

This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load.

Unraveling the Complexities of Ozone and PM2.5 Pollution in the Pearl River Delta region: impacts of Precursors Emissions and Meteorological factors, and Effective Mitigation Strategies

Ozone (O3) and fine particulate matter (PM2.5) are known to be interconnected due to shared precursor compounds. While numerous studies have examined the impact of precursors and meteorological factors on compound pollution events, few have proposed effective mitigation strategies tailored to specific regions. In this study, we conducted simulations of two types of O3 and PM2.5 pollution events in the Pearl River Delta (PRD) region during 2018 using the GEOS-Chem model. We applied a multiple linear regression model to quantify and distinguish the contributions of precursor emissions and meteorological factors to these events. Our findings highlight the predominant role of precursor emission factors in driving these pollution events. Notably, reducing NOx emissions in the Pearl River Estuary (PRE) region was found to exacerbate O3 pollution during specific periods, while reducing emissions of C4 alkanes (ALK4), lumped C3 alkenes (PRPE) and NH3 in proportion to their respective contributions emerged as an effective strategy to mitigate combined O3 and PM2.5 pollution. This research elucidates the mechanisms underlying O3 and PM2.5 compound pollution in the PRD region and presents a practical and significant approach to managing air pollution in this area.

Advancing urban mobility in developing countries: A mobile RSU approach for sustainable transportation

AbstractThe rapid and uncontrolled urbanization of cities in developing countries has engendered a plethora of urban mobility issues, including traffic congestion, accidents, and air pollution. To address these challenges, contemporary urban mobility trends are incorporating innovative technologies and sustainable governance practices. This article investigates how urban managers can leverage the opportunities presented by cost‐effective technologies and the management of urban data to enhance urban mobility in developing countries. Within this discourse, an RSU‐based approach is proposed that employs motorbike taxis for inter‐vehicular communication, given their status as the most widely used form of public transportation. This approach substantially diminishes investment costs and reinforces the sustainability of urban mobility. Through the implementation of this solution, a noteworthy reduction is anticipated in the emission of gases such as CO2, and NOx, known contributors to climate change and various respiratory diseases. To validate the efficacy of the proposed solution, four distinct scenarios are scrutinized in a case study centered on the city of Douala in Cameroon, utilizing tools such as OMNET++, SUMO, Veins, and INET. The proposed framework offers significant benefits in terms of environmental sustainability and operational efficiency. It enables a 10% reduction in CO2 emissions, a 15% reduction in NOx emissions, an 11% drop in fuel consumption, and a 15% reduction in waiting time in traffic jams. The envisaged solution aims to aid urban managers in their decision‐making processes, specifically in advancing sustainable urban mobility. Through the adoption of this approach, cities in developing countries can mitigate challenges associated with urban mobility and enhance the overall well‐being of their residents.

Experimental multiple parameters optimization of the injection strategies for a turbocharged direct injection hydrogen engine to achieve highly efficient and clean performance

Improving the brake thermal efficiency (BTE) and reducing NOx emissions are two main goals for hydrogen-powered internal combustion engines to achieve efficient and clean performance. This paper focuses on the multiple parameters optimization of injection and ignition both experimentally and numerically based on a 2.0L turbocharged direct injection hydrogen engine. Firstly, the effects of single and split injection on engine performance, in-cylinder mixing and combustion characteristics are investigated. Secondly, the single-factor effect of split injection parameters and spark timing on engine performance are obtained with different engine speeds. Significant interaction effects are detected between these factors. Thus, a multi-parameter optimization is conducted based on the response surface methodology method to analyze the co-relationship of factors (split injection control parameters and ignition) on responses (BTE, NOx emissions, and knock intensity) at high-load. Finally, a maximum BTE of 43.03 % and a reduction in NOx emissions by 71.19 % are achieved with the help of model prediction at 2500 rpm and a load of 1.40 MPa. Further optimization of other engine speeds is conducted, and the boundary of high-efficiency region (BTE>40 %) covers over 50 % of the load map after optimization. These results can provide valuable support for the performance improvement of efficiency and clean hydrogen engines.

Efficient and low-NOx combustion in a grate-fired boiler by feeding biomass non-uniformly along grate width: An integrated modeling study with experimental validation

The distribution of air flows and fuel feeds are two crucial operational parameters determining the high-efficiency combustion and low-nitrogen emissions in biomass-fired grate boilers. However, current optimizations primarily focus on air distribution, with limited attention given to fuel feeds optimization. In this study, a three-dimensional integrated model was developed in FLUENT platform for simulating a grate-fired boiler with four feed inlets, in which the DPM model was adopted to track particle information in detail, and the Ergun model was used to account for the flow resistance generated by the thick packed bed, implemented in the form of a UDF code. The reliability of the model was validated through comprehensive on-site experimental data. It was found that key parameters such as temperature and ignition front of char are non-uniformly distributed along the width of the four grates. Specifically, a significant lag in volatiles release and char oxidation occurs near the water-cooled wall on both sides. On this basis, the optimization strategies on improving efficient and low-NOx combustion were proposed by redistributing the biomass fuel from near the sidewalls to the middle sections, and the optimal non-uniform feeding mode along the grate width was found. Results demonstrate that when the mass ratio of fuel between the middle and side grates is 0.30 to 0.20, yielding a maximum overall char burnout ratio of 84.74 %. Additionally, the concentration of NO decreases from 163.2 mg/m3 of uniform feeding mode to 149.4 mg/m3 (at 11 % O2). These predictions will provide reliable theoretical guidance for enhancing boiler efficiency and reducing NOx emissions in grate-fired boilers.

Towards cleaner energy: An innovative model to minimize NOx emissions in chemical looping and CO2 capture technologies

The urgent global challenges of climate change and environmental issues have catalyzed the development of CO2-capture-ready technologies incorporating fluidization, such as fluidized bed (FB) and circulating fluidized bed (CFB) combustion under oxy-fuel conditions, chemical looping combustion (CLC), chemical looping with oxygen uncoupling (CLOU), in-situ gasification chemical looping combustion (iG-CLC), and calcium (or carbonate) looping (CaL) systems. While these technologies have the potential to reduce CO2 emissions significantly, the persistent presence of nitrogen oxides (NOx = NO + NO2) as pollutants remains a critical environmental concern.This paper introduces a comprehensive fuzzy logic-based model for predicting NOx emissions (FuzzyNOx model) from solid fuel combustion in fluidized beds of chemical looping systems. This innovative model takes into account a wide range of operating parameters, including fuel type, fuel particle size, fuel moisture content, air/fuel ratio, and temperature. It also explores advanced coal and biomass combustion modes, including air-firing, oxyfuel, iG-CLC, and CLOU. Furthermore, it delves into the intricacies of two distinct facilities: the 5 kWth dual-fluidized bed Chemical-Looping-Combustion of Solid-Fuels (DFB-CLC-SF) facility at Czestochowa University of Technology, Poland, and the calcium looping dual-fluidized bed (CaL DFB) facility at Niigata University, Japan.Bituminous coal, semi-anthracite, and wood chips are utilized as fuels. Moreover, three various oxygen carriers (OCs) for chemical looping combustion were employed, namely ilmenite, copper oxide (60 % wt.) supported by carbonate waste from ore flotation, and copper oxide (60 % wt.) supported by ilmenite (20 % wt.) and fly ash. Bituminous coal, semi-anthracite, and wood chips are utilized as fuels.The developed knowledge-based fuzzyNOx model allows the optimization of operating parameters to reduce NOx emissions from CO2 capture technologies.

Energy, environmental, economic, and social assessment of photovoltaic potential on expressway slopes: A case in Fujian Province, China

Expressway slopes within the boundary of expressway construction land have the potential to be transformed from conventional land use to valuable utilization through the installation of photovoltaic (PV) systems. Considering the continuous increase in expressway mileage, the PV potential could be enormous; therefore, a method to quantify such potential is urgently needed. This study proposes a potential assessment method for expressway slope photovoltaics. First, the suitable locations of expressway slopes for installing PV systems are identified on the basis of publicly available digital maps, combined with the principles of PV site selection and geographic information systems. Then, the PVsyst model is used to simulate the power generation efficiency and power output of the PV systems and to evaluate their PV potential, contribution, and economic benefits. The implementation of the proposed method in Fujian Province, China, indicates that the installed capacity of PV systems could reach 16.3 GW, with an annual power output of 17,940 GWh, contributing to the peak shaving of power grids and regional energy supply. The reductions in CO2, SOx, and NOx emissions are 16.65 Mt, 8970 t, and 3947 t per year, respectively. Considering carbon trading, the payback period is shortened to 11.7 years, with the return on investment of 65.38 % and the net present value of 52.6 billion RMB over a 25-year operational period. Additionally, this project could create 19.88 % of jobs in the energy sector in Fujian Province, providing 27,861 jobs during the construction phase and 18,248 jobs during the operation and maintenance phase. Thus, this project is economically viable and generates positive energy, environmental, and social benefits, contributing to the promotion of local energy transition and sustainable development.

Flow field and emission characterization of a novel enclosed jet-in-hot-coflow canonical burner

The jet-in-hot-coflow is a canonical combustion setup, which has been used in several studies to study Flameless/MILD combustion and auto-ignition of fuels. However, the NOx and CO emission measurements from these combustion setups were not possible due to the entrainment of laboratory air and a lack of a well-defined physical system limit. These limitations have been overcome by a new enclosed jet-in-hot-coflow setup. The combustor was operated by injecting a mixture of CH4-Air in the central jet, and the coflow comprised of hot products from CH4-Air combustion in burners upstream. The coflow composition was further controlled by adding diluents such as N2 and CO2. Measurements were done using stereoscopic particle image velocimetry, suction probe gas analysis, thermocouples, and chemiluminescence imaging. Increasing central jet velocity and equivalence ratio led to lower NOx and a reaction zone that enlarged and shifted downstream. The reduction in NOx emission was attributed to the returning mechanism. Adding CO2 and N2 as diluents in the coflow resulted in a longer combustion zone and reduced temperatures in the combustion chamber, leading to decreased NOx production and increased reburning. These experiments provide relevant flowfield and emissions data for modelers and help characterize combustion regimes such as Flameless/MILD.