Pollutant Emission Characteristics Research Articles

Simulation studies of pollutant emissions from road vehicles using models for inventories of pollutant emissions

Countries are obliged by international regulations to conduct annual pollutant emissions inventories. Road transport is one of the sectors for which an inventory of pollutant emissions is carried out. Determining pollutant emissions from road transport is possible only by modeling these emissions – that is why unified emission models are used. In this work, the COPERT and HBEFA INFRAS software are used to determine pollutant emissions characteristics for various vehicle traffic models. The article presents the principles of modeling pollutant emissions from road vehicles. The rules for qualifying road vehicles into elementary and cumulative categories have been systematized. Models of road vehicle traffic and ways of taking them into account in modeling pollutant emissions are presented. The following emissions of pollutants harmful to the health and life of living organisms are considered: carbon monoxide, non-methane volatile organic compounds, nitrogen oxides and total suspended particles. The trends of the national annual emissions of the tested pollutants in the years 2000 – 2020 and the results of simulation tests of pollutant emissions models are presented.

Investigation of the Combustion Properties of Ethylene in Porous Materials Using Numerical Simulations

As industrial modernization advances rapidly, the need for energy becomes increasingly urgent. This paper aims to enhance the current burner design by optimizing the combustion calorific value, minimizing pollutant emissions, and validating the accuracy of the burner model using experimental data from previous studies. The enhanced porous medium burner model is used to investigate the burner’s combustion and pollutant emission characteristics at various flow rates, equivalence ratios, combustion orifice sizes, and porosity of porous media. In comparison with the previous model, the combustion traits during ethylene combustion and the emission properties of pollutants under various operational circumstances have been enhanced with the enhanced porous medium burner model. The maximum temperature of ethylene combustion in the enhanced model is 174 k higher than that before the improvement, and the CO emissions are reduced by 31.9%. It is believed that the findings will serve as a guide for the practical implementation of porous media combustion devices.

Numerical analysis of the landing and take-off cycle standard for supersonic engines based on pollutant emission characteristics

To meet the requirements of the update for the supersonic landing and take-off (LTO) cycle standard, a methodology for studying the LTO supersonic standard based on pollutant emission characteristics is proposed in this paper to analyze the thrust and time of the LTO. In this study, three distinct supersonic engine models were developed based on subsonic engine cores. Subsequently, the pollutant emission calculation models were developed to calculate the pollutant emission index (Ie) of supersonic engines and analyze the pollutant emission characteristics. Findings confirmed the presence of a correlation between standard formulations and pollutant emissions. Finally, considering that the current LTO standard leads to excessive noise during the climb phase and inefficient combustion during the taxi/ground idle phase, the LTO supersonic standard was analyzed for the trade-off, which resulted in the more applicable and fairer standard being formulated. The results indicate that the LTO supersonic standard formulated in this paper proves to be more reasonable than the current LTO standard and accurately represents the pollutant emission characteristics of distinct supersonic engines during both the climb and taxi/ground idle phases. Consequently, this study's results have guiding significance for formulating the future LTO supersonic standard and predicting pollutant emissions from supersonic engines.

Pilot-tests of the coal-fired power plant indirect coupling with multi-source organic solid waste incineration technology

The production of organic solid waste is increasing as the development of society. However, the investment of waste incineration power plant is very high and the thermal efficiency is very low. At the same time, the load of coal-fired power plant is suppressed due to the carbon neutralization policy. Therefore, using the existed coal-fired power plant to co-process the organic solid waste is a feasible method. In this paper, a coal-fired power plant indirect coupling with waste incineration technology based on flue gas circulation was proposed and studied on a 100 kW pilot-test bench. In this technology, the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) was reduced by a three stages controlling method, which adopts the blending of multi-source organic wastes, high-temperature decomposition and selective catalytic reduction (SCR) catalyst decomposition, simultaneously. The effects of waste incineration coupling, replacement ratio of coal, and flue gas circulation on the combustion and pollutant emission characteristics of the system were studied. The experimental results indicate that the waste incineration coupling has minor influence on the temperature distribution and the toxicity of fly ash of the coal-fired furnace. The NO, HCl, and PCDD/Fs concentrations of flue gas of coal-fired furnace generally decrease as the replacement ratio of coal increases, while the SO2 concentration increases. With the help of three stages controlling method or the flue gas circulation, the PCDDFs concentration of the flue gas of coal-fired furnace can be much lower than 0.1 TEQ ng/Nm3.

Numerical studies of a water-cooled premixed burner for low NOx combustion of natural gas

Natural gas, known for its high combustion efficiency and low CO2 emissions, is experiencing a significant increase in both market share and application range. Despite these advantages, there are also challenges emerged during the combustion process, including occurrence of high flame temperature, difficulty in controlling nitrogen oxide emissions, combustion instability, and a tendency to backfire. To address these issues and achieve clean and stable burning, a novel 14 MW water-cooled pre-mixed burner has been developed. In-depth simulations are conducted to assess the impact of various structural and operating parameters on combustion and pollutant emission characteristics. Results indicate that the combustion temperature follows a “W" shape with height of the low cooling component while its width governs combustion stability. Gas inlet spacing influences the flame center position and anti-backfire performance. The flare angle of gas channels determines the minimum ignition energy of the mixed gas fuel which affects ignition point and flame center position. Although large height of high cooling component contributes to low NOx emissions at the gas outlet, the resultant low temperature is undesirable for combustion stability. Further examinations of operating parameters through simulations reveal that combustion temperature initially decreases and then increases with excess air coefficient, while a significant decrease is noted with lower operating load. The premixed water-cooled technology could achieve low-NOx emissions to 2.89 mg·Nm−3 with the combustion temperature controlled at 1642K. This study provides valuable data for the design of low-NOx gas burners, serving as a reference for achieving clean and stable combustion of gas fuel.

How we deal with transition planning as we approach the e-bus era

With the rapid development of new energy, the widespread adoption of electric buses is significant. This paper delves into the environmental impact, economic implications, and strategic planning solutions associated with the proliferation of electric buses. We initiate this process by using bus data from Qingdao, China. Subsequently, using the fuel life cycle method, we carefully examined CO and the pollutant emission characteristics of Qingdao bus fleet before and after electrification. The research results reveal that CO, nitrogen oxides, and VOC emissions have all increased. An economic analysis of electric vehicle adoption in public transportation was conducted in response to the second question. Considering government subsidies, a cost-saving model for electric vehicles per 100 kilometers was constructed. Furthermore, the study found that as the electrification rate increases, the operating costs of electric buses in Qingdao gradually decrease. We developed a comprehensive linear integer programming model to address the third question. The model, aimed at achieving the lowest comprehensive cost while considering various constraints, was solved through the branch and bound method. We applied this model to analyze the optimal plans for completing the conversion of electric buses in Qingdao, Zhengzhou, and Xi’an within a 10-year timeframe. For the fourth question, we have put forward policy recommendations.

Comprehensive experimental investigations on Co-combustion dynamics and multi-pollutant formation characteristics of coal gangue and biomass in oxy-fuel atmosphere

Based on the co-combustion principle of coal gangue and biomass, the combustion characteristics, kinetic mechanisms, and pollutant emission characteristics of mixed coal gangue and wheat straw in oxy-fuel atmosphere were investigated by conducting experiments with a thermogravimetric analyzer and a tube furnace in this paper. The results indicated that the comprehensive combustion characteristics, reaction rate and burnout rate of the samples can be improved with the increase of O2 concentration in oxy-fuel atmosphere. When O2 concentration is 50 %, the emission peaks of pollutants SO2 and NOx are the highest. The increase of biomass content can accelerate the combustion reaction rate, increase the total weight loss rate, enhance the comprehensive combustion characteristics of the samples significantly, and reduce the release of SO2. A faster heating rate corresponds to higher ignition temperature, burnout temperature, and the maximum weight loss rate temperature, leading to the improvement of comprehensive combustion characteristics and flammability. The combustion temperature has a significant effect on pollutant release, and the release of CO and SO2 is relatively low under the condition of 900∼1000 °C. Therefore, the use of oxy-fuel co-combustion technology holds the potential to significantly improve the combustion performance of coal gangue, reduce pollutant emissions, and provide a theoretical guidance for the resource utilization of coal gangue and biomass.

Numerical Analysis of the Effects of Fuel Injection Duration and Spray Angle on the Combustion Process in a Compression Ignition Engine

The changes in injection strategies for diesel engines have a major impact on the performance and pollutant emission characteristics of diesel engines. If injection strategies like injection duration, injection timing, injection pressure and spray angle are properly adjusted, combustion can be improved. The engine performance will increase and emissions will decrease with the combustion improvement. In this work, the influences of injection duration and spray angle on the combustion characteristics of single cylinder, natural aspirated, electronically controlled injection, compression ignition engine were investigated. In the first stage of the work, experiments were executed on a single cylinder CI engine using a Cussons P8160 DC dynamometer. After the experiments, the piston bowl geometry of the engine was modeled and numerical simulation studies were achieved at 7 different injection durations and 7 different spray angles using Converge CFD software. As a result of this study, it was observed that there is a good match between experimental and simulation data of heat release rate (HRR) and in-cylinder pressure. In-cylinder pressure decreased with longer injection duration. The highest max. in-cylinder pressure was roughly 101.0 bar at 4°CA injection duration and the lowest max. in-cylinder pressure was roughly 82.0 bar at 10°CA injection duration. When the HRR data were analyzed, it was seen that as the injection duration increased, the amount of heat released by combustion decreased. When examining the results of the spray angle analysis, it was concluded that there were not very large differences in-cylinder pressure and HRR data, and there was a difference of 1.4 bar between the highest and lowest max. in-cylinder pressure values. In addition, the highest in-cylinder pressure of approximately 86.7 bar was obtained at a spray angle of 77°. It was observed that the CA50 value was obtained at angles closer to the top dead center by increasing the spray angle and decreasing the injection duration. Moreover, the longest combustion durations were realized at 60° spray angle and 10°CA injection duration.

Feasibility of co-disposal of lignite and eucalyptus wood in coal-fired power plants: thermogravimetric characterization, typical gaseous pollutant emission characteristics, and economic analysis

ABSTRACT Energy issues are becoming increasingly prominent, and biomass blending in coal-fired power plants can improve combustion performance and reduce gaseous pollutant emissions, thereby improving economic efficiency. In this study, a thermogravimetric analyzer, a horizontal tube furnace, and an infrared flue gas analyzer were used to investigate the combustion behavior and gaseous pollutant emissions of the co-combustion of LC and EW. The results show that blending EW into LC cofiring can inhibit the release of volatile matter and promote the decomposition of fixed carbon and lignin simultaneously. The HHV of EW (15.88 MJ/kg) reaches 63.7% of LC’s (24.90 MJ/kg), indicating EW has a high energy utilization value. With increasing combustion temperature, the average value of CR S increased from 47.09% to 59.94%, and the average value of CR Cl increased from 26.15% to 52.15%, leading to a significant increase in SO2 and HCl emissions. The decrease in combustion temperature slightly promoted the release of N (CR N increased from 11.76% to 14.45%). The results of the economic analysis show that the cost of CaO and NH3·H2O used for removing gaseous pollutants decreased the most, and the economic efficiency increased the fastest to 14,000 RMB/day when the EW blending ratio increased from 10% to 20%.

Emission and spatial variation characteristics of odorous pollutants in the aerobic tank of an underground wastewater treatment plant (UWWTP) in southern China

In this study, the spatial concentration of odorous pollutants in the aerobic tank of an underground wastewater treatment plant (UWWTP) in southern China is monitored. The odour activity value, odour contribution rate, and chemical concentration contribution rate are used to evaluate the degree of contribution of odorous substances. Computational fluid dynamics (CFD) simulations of odorous pollutant diffusion are also established. The study shows that the odorous substances detected in the aerobic tank mainly included ammonia (NH3), hydrogen sulfide (H2S), trimethylamine (C3H9N), and methanethiol (CH3SH), and their concentrations are 1.160, 0.778, 0.022, and 0.0006 mg/m3, respectively. The total odour activity value of the aerobic tank is 450.72 (dimensionless), of which the odour activity value of H2S is 432.22, and the contribution rate reaches 95.9%. H2S is the main contributor to odour and a key controlled substance. The air inlets and exhaust outlets in the aerobic tank are cross-arranged at the top of the space, and the CFD model of odorous pollutant diffusion shows that the gas flow organization determines the odorous pollutant diffusion. The spatial distribution of gas flow and odorous substances in the aerobic tank is relatively uniform, and the odour collection efficiency is higher. The production flux and production coefficient of H2S in the aerobic tank are calculated as 25.831 mg/(m2·h) and 14.149 mg/t, respectively. This study determines the reasonable air supply and exhaust design of the aerobic tank, the number of odour pollutants, and the key controlled substances. These findings offer guidance and serve as useful references for the prevention and control of odour pollution in aerobic tanks of the same type of UWWTPs.

Distribution of gasification products and emission of heavy metals and dioxins from municipal solid waste at the low temperature pyrolysis stage.

Gasification is widely regarded as one of the most practical, economical, and environmentally friendly waste disposal technologies for municipal solid waste (MSW). The pyrolysis stage (300-500°C) is crucial for weight loss during MSW gasification, as a considerable amount of organic matter breaks down, producing high-value synthesis gas. This study investigated the product distribution and pollutant emission characteristics within this temperature range and its influencing factors during MSW gasification using a self-designed MSW gasification device. Results indicated that MSW underwent approximately 70% weight loss within this temperature range, yielding low amounts of inorganic and short-chain organic products, with mainly long-chain organic compounds of C16-C34. The atmosphere variation had minimal effect on the elemental composition and content of solid phase products. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) analyses showed that Mn and Zn were the primary components of heavy metal leaching toxicity in solid phase products, with their contents increasing as temperature increased. Synthesis gas showed the highest content of heavy metal As element, reaching a peak at 400°C. Higher gasification temperature and lower oxygen flow rate significantly reduced the dioxin content and I-TEQ values, with highly chlorinated isomers being the predominant dioxin isomers. Nonetheless, low-chlorinated dioxins accounted for more than 50% of the I-TEQ. This study improves our understanding of the gasification process of MSW.

Biodiesel from blended microalgae and waste cooking oils: Optimization, characterization, and fuel quality studies

<abstract> <p>Petrodiesel is an unsustainable and undependable fuel owing to its environmental concerns and depleting reserves. Biodiesel is a sustainable alternative fuel to petrodiesel with a better fuel quality and minimum environmental impacts. However, cost-effective biodiesel production requires the use of a sustainable feedstock and process optimization. This study explored biodiesel yield optimization from mixed microalgae oil (MO) and waste cooking oil (WCO). The use of mixed feedstock for biodiesel production relieves the rising demands; lowers feedstock costs; and improves the fuel quality, engine performance, and pollutants emission characteristics. MO was extracted from dried microalgae biomass by the Soxhlet method using hexane. The MO and WCO were purified and characterized, and an oil blend with suitable properties (best in kinematic viscosity, density, higher heating value, and acid value compared to other blends) was selected. The transesterification experiments designed by central composite design were optimized using the response surface methodology. Experimental results underwent regression analysis to develop a quadratic model equation for predicting the optimum level of parameters and biodiesel yield. Model fitness and variables effects on biodiesel yield were studied using analysis of variance. The optimization experiment achieved 98.82% oil conversion rate at the catalyst loading of 2.0 w/v%, molar ratio of 12:1 v/v, reaction temperature of 60 ℃, and reaction time of 100 min. A triplicate validation experiments achieved 97.72% conversion rate, which is very close to the model predicted result (99.1%). Biodiesel from MO-WCO showed a better cetane number (77.76), iodine value (12.90 gI<sub>2</sub>/100 g), acid value (0.049 mg KOH/g), HHV (43.25 MJ/kg), kinematic viscosity (4.50 mm<sup>2</sup>/s), pour point (–2.5 ℃), and flash point (180 ℃). In conclusion, the study revealed that transesterification of blended MO-WCO led to a maximum biodiesel and the reaction time and temperature were found to be the most significant factors affecting the yield of biodiesel. Furthermore, biodiesel from blended MO-WCO is a sustainable and environmentally friendly alternative fuel source which can contribute towards a promising industrial scale biodiesel production in the future.</p> </abstract>

Data-driven method for estimating emission factors of multiple pollutants from excavators based on portable emission measurement system and online driving characteristic identification

This study aims to explore the factors that influence the emission characteristics of multiple pollutants from non-road mobile machinery (NRMM) under real-world conditions and to establish a data-driven method for calculating accurate emission factors. This research focused on NRMM excavators meeting the third-stage emission standards and identified the actual work characteristics of 108 excavators in different scenarios based on a self-developed testing system for 368,000 h. Additionally, a portable emission testing system (PEMS) was used to study the instantaneous emission characteristics under different driving styles and modes for 10 EC210 excavators with the largest engineering construction inventory. The results showed that the average time proportions of idling, working, and moving modes for excavators were 21 %, 66 %, and 13 %, respectively. The results also revealed that the instantaneous emission rates of multiple pollutants varied significantly under different driving styles and modes. Driving style affected the hydraulic pump power change rate through hydraulic pilot pressure, and engine load surge caused turbocharger response delay and in-cylinder combustion deterioration, which affected pollutant emissions. Driving mode affected the emission characteristics of idling, high-speed idling, moving, and working modes of excavators through the external characteristics corresponding to the engine speed gear set. The data-driven method for calculating emission factors differed from the traditional method for most indicators to varying degrees. In terms of fuel-based emission factors (EFfs), except for the EFfNOx indicator, which was 7.859 % higher than the traditional method, the other three indicators were significantly lower than the traditional method. In terms of power-based emission factors (EFps), except for EFpPM and EFpPN, the other two indicators were much higher than the traditional method. EFpCO and EFpNOx were 7.93 % and 20.332 % higher than the traditional method, respectively. It is recommended to use the data-driven method based on the actual driving data distribution to provide scientific support for accurately establishing the emission inventory.

A high-resolution (0.1° × 0.1°) emission inventory for the catering industry based on VOCs and PM2.5 emission characteristics of Chinese multi-cuisines

Catering enterprises gather in densely populated areas, whose pollutant emission has an important impact on human health and environmental quality. This study investigated detailed information of 5456 catering enterprises in a typical city, and analyzed PM2.5 and VOCs components of 15 catering cuisines and different scales. Based on the measured emission factors, the basic information of nationwide catering enterprises and the population density, this study established the national catering pollutant emission inventory with the spatial resolution of 0.1° × 0.1°. As the results showed, alkanes, alkenes and oxygenated volatile organic compounds (OVOCs) were the main components in VOCs of most catering cuisines, accounting for 36.6%–96.7%, while organic carbon (OC) was the dominant component in PM2.5, accounting for 55.4%–68.6%. The same cuisine of different scales also presented certain differences in emission characteristics. The total emissions of the ozone formation potential (OFP) and secondary organic aerosols formation potential (SOAFP) were 1737.8 kt and 76.4 kt, respectively, with alkanes and OVOCs being the main contributors, contributing 27.5% and 22.3%, respectively. Acetaldehyde, ethylene, propylene and the other top ten VOC species contribute 81.0% of the total OFP emissions, while toluene contributed much more to total SOAFP emissions than other VOC species, contributing 35.9%. The air pollutant emissions showed the highest correlation with the population, and the regions with prominent emissions were mainly concentrated in the Beijing-Tianjin-Hebei (BTH) region and coastal cities. This study is a systematic understanding of air pollutant emission characteristics of the catering industry in China, which has important supporting value for pollutant emission reduction planning in the catering industry.

Co-drivers of Air Pollutant and CO2 Emissions from On-Road Transportation in China 2010-2020.

Co-controlling the emissions of air pollutants and CO2 from automobiles is crucial for addressing the intertwined challenges of air pollution and climate change in China. Here, we analyze the synergetic characteristics of air pollutant and CO2 emissions from China's on-road transportation and identify the co-drivers influencing these trends. Using detailed emission inventories and employing index decomposition analysis, we found that despite notable progress in pollution control, minimizing on-road CO2 emissions remains a formidable task. Over 2010-2020, the estimated sectoral emissions of VOCs, NOx, PM2.5, and CO declined by 49.9%, 25.9%, 75.2%, and 63.5%, respectively, while CO2 emissions increased by 46.1%. Light-duty passenger vehicles and heavy-duty trucks have been identified as the primary contributors to carbon-pollution co-emissions, highlighting the need for tailored policies. The driver analysis indicates that socioeconomic changes are primary drivers of emission growth, while policy controls, particularly advances in emission efficiency, can facilitate co-reductions. Regional disparities emphasize the need for policy refinement, including reducing dependency on fuel vehicles in the passenger subsector and prioritizing co-reduction strategies in high-emission provinces in the freight subsector. Overall, our study confirms the effectiveness of China's on-road control policies and provides valuable insights for future policy makers in China and other similarly positioned developing countries.

Emission Characteristics of Heavy-Duty Vehicle Diesel Engines at High Altitudes

The aim of this study was to accurately quantify the emission characteristics of pollutants at different altitudes. We used an intake and exhaust altitude simulation system that could simulate the intake and exhaust pressures of a national sixth vehicle diesel engine at different altitudes. Experimental research was conducted on the World Harmonized Transient Cycle (WHTC) and World Harmonized Steady State Cycle (WHSC) of the diesel engine. The results showed that carbon monoxide (CO) emissions increased with the altitude at full load, but their rates were significantly reduced at low speed (800 rpm), increasing by 0.0084–0.665 ppm/m. Hydrocarbon (HC) emissions showed an initial decreasing and then increasing trend, with a rise of up to 30%. Nitrogen oxides (NOx) showed a linear decreasing trend, especially at low speed. With the increase in altitude, the cycle work of the diesel engine decreased in a non-linear manner, and the decrease became more pronounced above 3000 m. The raw emission results of the WHTC and WHSC tests also revealed that CO increased exponentially, NOx decreased slightly and then increased rapidly, HC increased linearly, and the emissions of all pollutants deteriorated significantly above 3000 m. The exhaust emission results of the WHTC and WHSC tests showed that the CO emission showed an initial decreasing and then increasing trend with the elevation of the altitude, approximately 15 ± 5 mg/kWh. HC emissions showed an increasing trend, with HC emissions of 3 – 6 mg/kWh for the WHTC and 1 – 2 mg/kWh for the WHSC. NOx emissions did not follow any obvious rule, while the particulate matter (PM) tended to increase and then decrease with the elevation of the altitude. In relation to the current emission standards, the limit value margin for CO and HC exhaust emissions is greater than 95% and the limit value margin for PM emissions is greater than 88% at an altitude of 4000 m. The NOx emission limit is greater than 87% (within 3000 m), but there is a risk of exceeding the limit above 3000 m. The second sampling data from the WHTC and WHSC showed that the raw emissions of the engine were higher in the high-altitude area than in the low-altitude area, but the change law of the exhaust emissions was not obvious, and the levels of both emissions were low.

Emission of nitrogen/sulfur pollutants and migration of heavy metals during combustion of oily sludge from the oil refining process in fluidized bed

Oily sludge is a kind of hazardous waste due to the enrichment of nitrogen, sulfur, and heavy metals. In this work, the combustion of oily sludge from an oil refining factory in a fluidized bed reactor at 850–1050 °C and 0.8–1.2 excess air ratios were studied, with a focus on emission of nitrogen and sulfur pollutants and migration of Cr, Ni, Cu, Zn, Cd, Pb. The emission characteristics of nitrogen and sulfur pollutants were exhibited through monitoring the flue gas. The migration characteristics of heavy metals were clarified by analyzing their retention in bottom and fly ash. Moreover, the BCR (European Community Bureau of Reference) sequential extraction of the heavy metals in bottom ash was also carried out to obtain the migration of heavy metals in different forms. The contents of NOx and SO2 in the flue gas increased with temperature and excess air ratio increasing. High temperature led to less heavy metal retention in the bottom ash. The strong oxidizing atmosphere can weaken the volatilization of heavy metals. The stabilities of the heavy metal in different forms were in the following order: F4 (residual fraction) > F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (exchangeable and acid soluble fraction). F4 was the dominant fraction of heavy metals in the bottom ash. The >60 % content of F3 and F4 led to the high stability of Cu and Ni while the >57 % content of F1 and F2 led to the high volatility of Cd and Pb in bottom ash. The differences in the component map of F1-F4 for the six heavy metals gave rise to their different migration characteristics during combustion.

Effect of aromatic doping on the thermal and emissions characteristics of hydrogen-rich fuels in a semi-industrial scale furnace

This work experimentally investigates the effects of aromatic doping on the combustion and pollutant emissions characteristics of an H2-rich mixture (H2/CH4/CO) in a laboratory furnace featuring an industrial-grade burner. Benzene was added to a reference H2-rich fuel mixture (up to 5%v/v) under varying stoichiometric conditions. Comprehensive temperature, exhaust emissions, and OH* and CH* chemiluminescence data were collected. This research aims to bridge the gap between laboratory-scale studies and industrial-scale applications to understand the role of aromatic compounds in NOx formation during hydrogen-rich combustion. The results highlight intriguing interactions among NO, flame temperature, and soot formation occurring in the presence of benzene. Benzene doping leads to two main competing effects: an increase of prompt NO due to enhanced CHi radical production coming from the aromatic ring oxidation; and a decrease of thermal NO when soot formation enhances flames’ emissivity, leading to increased heat transfer from the flame to its surroundings. The relative importance of the two effects governs the final NO emissions.

Study on the pollutant emission characteristics of the co-combustion of high S/Cl waste mixed with recycled papermaking waste

Using solid waste to replace coal for power generation is one of the effective ways to reduce CO2 emissions, but the incineration of some high-sulfur and high-chlorine solid waste will lead to the increase of pollutant emissions. This paper proposed a new way to self-control pollutant emissions by co-incinerating different solid wastes with specific properties. In this work, the recycled papermaking waste residue (RPR) and sludge (RPS) with high calcium content were chosen to co-combustion with high-sulfur and high-chlorine solid waste, and the emission characteristics and control mechanism of pollutants under co-combustion were explored. The primary calcium compound in the recycled papermaking solid waste was CaCO3. When RPR and RPS were mixed at a ratio of 1: 1, HCl could be fully captured, resulting in the least emissions. Pollutant emissions was controlled by adding RPR and RPS to high-sulfur textile dyeing sludge and polyvinyl chloride. The sulfur-fixing efficiency rose from 65 % to 91 % and the chlorine-fixing efficiency rose from 69 % to 93 % with an increase in Ca/(S + 0.5Cl) from 1 to 3. As the reaction temperature rose from 700 °C to 1000 °C, the sulfur-fixing efficiency and chlorine-fixing efficiency initially increased and subsequently dropped. The CaCO3 in the material was rapidly decomposed at 800 °C, which accelerated the positive reaction rate with SO2 and HCl, so that the sulfur-fixing efficiency and chlorine-fixing efficiency reached the maximum, which were 89 % and 92 %, respectively. CaSO4 and CaClOH were the principal reaction products at the temperature range of 700 °C to 1000 °C.

Towards sustainable transport: quantifying and mitigating pollutant emissions from heavy-duty diesel trucks in Northeast China.

Heavy-duty diesel trucks (HDDTs) have caused serious environmental pollution in China. Accurate estimation of their pollutant emission characteristics is essential to reduce emissions and associated environmental and public health impacts. To achieve sustainable development for transport emissions in Northeast China, we developed localized emission factors and a high-resolution emission inventory of HDDTs, based on on-board test, Guidebook and international vehicle emission (IVE) model. The results show that the total emissions of CO, NO, NO2, and PM from HDDTs in Northeast China in 2020 were 172.2 kt, 531.5 kt, 11.2 kt, and 921.4 t, respectively. In terms of spatial distribution, emissions decreased from the city center to the city fringe. Temporally, the NOx emission variation curves of different types of roads presented a "single-peak" emission characteristic, which was different from the peak of traffic flow. Three emission reduction scenarios are further developed in the paper. Scenario analysis shows that elimination of HDDTs that follow the old China III emission standard and installing tailpipe treatment devices are the most effective pollutant reduction measure. The reduction percentages for CO, NO, NO2, and PM ranged from 62.9 to 83.89%. The results of our study could inform policymakers to devise feasible strategies to reduce vehicle pollution in Northeast China.