Particulate Matter Emission Characteristics Research Articles

Car-Following Strategy Involving Stabilizing Traffic Flow with Connected Automated Vehicles to Reduce Particulate Matter (PM) Emissions in Rainy Weather

On highways, it is commonplace to observe car-following behavior among vehicles. Unfortunately, this behavior results in significant particulate matter (PM) emissions, which greatly contribute to environmental pollution. Additionally, adverse weather conditions such as rain can negatively affect vehicles’ car-following behavior and have further influences on their PM emissions. The technology of connected automated vehicles (CAVs) offers a promising solution for mitigating these negative influences. This paper investigates the effect of various rainy weather conditions on PM emissions during car-following behavior on highways and proposes a CAV car-following strategy to reduce these emissions. Firstly, we employed a calibrated car-following model of traditional vehicles to perform simulation experiments, examining characteristics of PM emissions under four levels of rain and two simulation scenarios. Secondly, based on the relationship between PM emissions and speed fluctuations, we proposed a CAV car-following strategy by stabilizing traffic flow to smooth speed fluctuations. The proposed CAV car-following strategy was then validated through simulation experiments, and its effectiveness in reducing PM emissions under rainy conditions was assessed. The results indicate that higher speed fluctuations during car-following behavior lead to more PM emissions in rainy weather. By utilizing the proposed car-following strategy, CAVs can significantly reduce PM emissions in rain conditions, with average reductions of 41.07%, 59.46%, 49.60%, and 71.66% under very light rain, light rain, moderate rain, and heavy rain conditions, respectively. The findings of this paper facilitate the assessment of PM emissions fluctuations in different rainy weather conditions, which in turn can contribute to the development of more effective PM emissions control strategies. The proposed CAV car-following strategy can smooth speed fluctuations, and improve traffic flow stability, thus reducing PM emissions in rainy weather. It has the potential to mitigate environmental pollution from the transportation sector.

Particulate matter emission characteristics of spruce, sunflower and maize: A comparison between nominal and reduced output in a small-scale boiler

The applicability of spruce, sunflower and maize for residential heating was investigated. Emission factors of gaseous and PM pollutants were established at both nominal and reduced output. Since automatic pellet boilers often operate at reduced output, understanding the differences in PM release and behavior is crucial. The emission factors for sunflower reached the highest values at 111.6 mg MJ−1 and 139.2 mg MJ−1 for nominal and reduced output, respectively. PM emission factors reached 49.5/39.5 mg MJ−1 for maize and 8.6/21.4 mg MJ−1 for spruce. It was shown that PM size distribution does not vary significantly between nominal and reduced output and is highly dependent on the fuel composition. The PM size peak was in the range of 0.377–0.596 μm for sunflower, 0.252–0.377 μm for maize, 0.152–0.252 μm for spruce at nominal output and 0.0941–0.152 μm for spruce at reduced output. The entrainment of coarse ash particles was found to be negligible. Cd, Pb, Tl and Sb were found almost exclusively on emitted particles, due to their high volatility and modes of occurrence. The release of inorganic matter into the flue gas was severely inhibited in maize due to the formation of refractory phases.

Experimental study on the airflow dynamics and particulate matter emission characteristics of cooking fumes during frying, roasting, and deep-frying

Clarifying the characteristics of thermal plume airflow dynamics and particle characteristics during different cooking processes is helpful for efficiently controlling cooking fumes. In this study, the flow and emission characteristics of cooking fumes produced during frying, roasting, and deep frying were investigated using quantitative schlieren techniques and particulate matter sensors. The results show that frying, roasting, and deep-frying have smaller vortex areas, but different to that produced when simply heating edible oil, with the three cooking scenarios exhibiting plume dispersion angles that are, on average, approximately 20° larger than that observed for the heated-oil case. Furthermore, the emission velocity of the source ranged from 0 to 0.5 m/s for the four cases (within a distance one-times the diameter of the emission source). The velocity of the heated-oil case was generally Gaussian distributed, whereas those of the cooking cases were parabolically distributed. All cases exhibited linear variations in sectional diffusion diameter and flow rate along the vertical direction. The three cooking cases exhibited linearly fitted slopes that are approximately 1.0–2.0-times greater than that of the heated-oil case, which is reflective of more ambient air entrained during cooking. Particles 1–2.5 μm in size were observed for the three cooking cases, while the deep-frying case exhibited an average particulate mass concentration more than twice that observed for the heated-oil, which significantly increases the danger of exposure to oil-fume particles. In summary, detailed cooking-fume data serve as boundary conditions for simulations and provide crucial insight for effectively capturing cooking fumes.

Characteristics of Particulate Matter Emissions for Low-Sulfur Heavy Oil Used in Low-Speed Two-Stroke Diesel Engines of Ocean-Going Ships

Characteristics of Particulate Matter Emissions for Low-Sulfur Heavy Oil Used in Low-Speed Two-Stroke Diesel Engines of Ocean-Going Ships

TEM characterization of particulate matter emissions from the bedding stage of a Cu-free brake friction material

Airborne particles in the aerodynamic diameter range of 1–2.5 µm, collected during the dynamometer bedding of a low metallic Cu-free brake friction material, have been investigated using a transmission electron microscopy (TEM) approach. A characterization protocol, based on the combination of imaging, diffraction, and spectroscopy data, has been applied to the particles collected at each bedding stage, to determine the phase and chemical composition of the particles. The results highlight the evolution of the tribological mechanisms occurring during bedding, having important effects on the whole lifetime performances, and are also interesting for developing better friction materials with reduced particulate matter emission, still complying with the required safety standards.

Characterization of particulate matter emissions from internal combustion engines using δ13C values: Impact of engine operation conditions and fuel type on PM10 isotopic composition

Stable carbon isotope ratio of particulate emissions from internal combustion engines (ICEs) is an important characteristic in atmospheric carbonaceous PM source studies. Long-term measurements (2009–2020) of δ13C values of commercial fuels in Lithuania were conducted to evaluate the current isotopic composition of the fuel due to the changing share of renewable energy sources (RES). In this work, we present experimental results on stable carbon isotope ratio (δ13C) in PM10 emitted by different types of ICEs (two-stroke and four-stroke), including on-road transport and non-road mobile machinery. Different driving scenarios were simulated on a test bench (idling, NEDC, different torque, and speed). At idle, the average δ13C(PM10) values of different fuel types were determined: −27.80‰ for gasoline, −28.97‰ for diesel, − 27.89‰ for biofuel-C3, and −16.95‰ for biofuel-C4. Isotopic fractionation during combustion in ICEs depended on fuel type. The magnitude of Δ13C was 3‰ for gasoline, 2‰ for diesel, 1.5‰ for biofuel-C3, and 0.6‰ for biofuel-C4. The δ13C values of ICEs-generated PM10 were found to be dependent on the amount biobased components such as hydrotreated vegetable oil (HVO) to the fuel. However, insubstantial differences were found between the δ13C of PM derived from pure diesel and from an ethanol/diesel blend (E40).

Comprehensive characterization of particulate matter emissions produced by a liquid-fueled miniCAST burner

Soot particles generated by a liquid-fueled miniCAST burner, supplied with diesel B7, was characterized for the first time over a total of 34 operating points covering an overall equivalence ratio ( ϕ) range of 0.103-1.645. To characterize the gas and particulate phase emissions, electron microscopy images, mobility-equivalent size distributions and mass concentration of the soot aggregates were recorded, and optical extinction/absorption coefficients of the exhaust were measured. The burner produces soot aggregates with geometric mean diameter size in the range 45-105 nm with primary particle size in the range 18-39 nm. The Ångström absorption exponent ( α) was evaluated in the range 400-1000 nm and was found to increase with ϕ and vary in the range 1.05-2.25. The interposition of a catalytic stripper in the sampling line was found to (i) flatten the shape of the size distribution of aggregates, (ii) oxidize most of the gas phase thus impacting optical extinction coefficients particularly below 400 nm and (iii) decrease α. The soot volume fraction ( fv) was determined by three independent methods: optical absorption, mass deposit and mobility size distribution combined with morphology data. fv evaluated from size mobility data accounting for morphological aspects agreed within 13% with fv measured optically and within 25% with fv evaluated from mass concentration measurements. The precise methodology developed to characterize engine-like soot particles produced by a liquid-fueled miniCAST can now be transposed to study other regular, renewable, and surrogate liquid fuels to investigate their physical and optical properties before considering their large-scale use.

Experimental studies on the particulate matter emission characteristics of a lateral swirl combustion system for direct injection diesel engines

To analyze the particulate emission characteristics of a lateral swirl combustion system (LSCS), experimental research on a single-cylinder diesel engine was done and compared against the Turbocharger-Charge Air Cooling-Diesel Particle Filter Series combustion system (TCDCS) at different conditions. Compared to the TCDCS, the LSCS presents better combustion performance and lower total particle emission characteristics: As for the LSCS, the vast majority of the particle number size distributions shifted downward, indicating a decrease in the particle number concentration. The total particle number and mass concentrations of the LSCS decreased by 8.7–62.4% and 15.2–55.6% at various loads. The number concentration of particles smaller than approximately 8 nm increased for the LSCS, which can be attributed to the higher temperature and more thorough fuel/air mixture, facilitating the oxidation of large particles into small particles. Combined with the simulation, the LSCS perfectly exerts the wall-flow-guided effect, remarkably improving the fuel/air mixing quality and reducing the local over-concentration regions, which can inhibit the formation of particles. Hence, the LSCS effectively reduces the particle number and mass concentrations, exhibiting excellent particulate emission characteristics.

Investigation on the mercury nucleation mechanism based on the release characteristics of inhalable particles during coupled combustion of sewage sludge-coal washery tailing

Establishing an integrated treatment technology system for sewage sludge and coal washery tailing by mixed combustion can effectively overcome the disadvantages of the low calorific value and utilization efficiency, realizing the efficient resource. The single-component and coupled fuel were analyzed. Aiming at the generated inhalable particulate matter during the combustion process, using multiple characterization means and the fluidized bed experimental system, the micro-characteristics and elemental distribution of coupled fuel and combustion products were obtained, and the theory based on nucleation control was analyzed to reveal particle size distribution and particulate matter emission characteristics under multiparameter coupling conditions. The nucleation mechanism of Hg on the surface of the particulate matter under mixed combustion conditions was clarified. The results show that the weight loss process of sewage sludge in the combustion process mainly includes four stages. An obvious boundary between the volatilization and combustion processes of fixed carbon does not exist; furthermore, there is some overlap between the two processes. Volatiles and minerals interact in the mixed combustion process. The constituent elements of PM1 and PM1∼10 in the generated particulate matter are mainly easily vaporizable and refractory elements, respectively. The particle size of the particles produced presents the characteristics of bimodal distribution. There is a critical value (800 °C) for the influence of combustion temperature on the emission characteristics of particulate matter. It mainly affects the emission characteristics of coarse and fine particles through dominating the occurrence forms of tar, easily gasified and refractory elements, and the collision and aggregation process between particles. Homogeneous nucleation and heterogeneous condensation are the basic pathways for the transition of Hg from the gas phase to particle nucleation, and there are different nucleation control mechanisms. The heterogeneous condensation process includes diffusion control and surface reaction control. In addition, after the coupled fuel is demineralized by acid washing, the nucleation control mechanism changes significantly from diffusion control to chemical reaction control for the particles in the continuum region.

The characteristics of PM emissions from construction sites during the earthwork and foundation stages: an empirical study evidence

The bulk of the particulate matter (PM) emissions generated during construction projects are significantly released during the earthwork and foundation stages. To reduce and control these emissions, it is necessary to have reliable data on their characteristics. However, construction PM are poorly characterized because their composition depends on several factors (e.g., weather and reduction measures) and various on-site activities whose effects may interact. To address these challenges, a long-term quantitative empirical study using advanced statistical methods was performed on a real construction project during the whole earthwork and foundation stages. The upwind-downwind method was used to collect data on PM emissions throughout the earthwork and foundation construction process, and correlation analysis, paired samples t-test, and partial least squares regression (PLS) were used to analyze TSP, PM10, and PM2.5 emissions and their relationships with various influencing factors. The results showed that both earthwork and foundation constructions generate substantial PM emissions because there were differences with statistical significances in the PM levels measured upwind and downwind of the construction site. TSP and PM10 emissions correlated moderately with humidity and wind speed. However, temperature and atmospheric pressure did not correlate significantly with any of the measured emissions. The main activities responsible for PM emissions during the earthwork and foundation construction stages were hammer piling, waste stacking, and materials transportation. Water spraying was found to effectively reduce TSP and PM10 emissions, while the use of a fog cannon more effectively reduced PM2.5 emissions. Construction PM is an important source of atmospheric pollution in cities; the findings presented herein provide cornerstone and knowledge to guide efforts for reducing its impact.

Emission Characteristics of Particulate Matter from Boiling Food

Cooking food in water or soup, such as hot pot, is a widely used cooking method in China. This type of cooking requires no oil and cooks at a lower temperature, but that does not mean it produces fewer pollutants or is less harmful. There are few research studies on the emission characteristics and mechanisms of particulate matter emissions when eating hot pot (the boiling process), which leads to the unreasonable design of ventilation systems for this kind of catering. In this paper, the effects of boiling different ingredients (including noodles, potatoes, fish, tofu, meatballs, and pork) on particle number concentration emissions were studied. The particle number concentration and particle size distribution of PM with diameters of 0.3 μm and less, 0.3–0.5 μm and 0.5–1.0 μm (PM0.3, PM0.3–0.5 and PM0.5–1.0, respectively) were measured in an experimental chamber. The food type and shape showed very little change in the PM emission characteristics of boiling. When the boiling state was reached, the number concentration, particle size distribution, and arithmetic mean diameter of particles all fluctuated within 60 s. The emission characteristics of particles produced by boiling water and heating oil were compared. Heating oil produced more small particles, and boiling water released more large particles. Transient and steady methods were used to calculate the emission rate of particles, and the steady-state calculation has a high estimation of the emission rate.

Comparative Study of Sub-23nm Particle Number Emission Characteristics for Non-road Diesel Engine on RMC and NRSC Test

A non-road diesel engine meeting China IV emission regulation was selected, the RMC and NRSC test procedures of the EU non-road Stage V emission regulation were run on the engine test bench. The emissions of particle number (PN) with particle sizes above 23 nm and 10 nm were tested simultaneously using direct exhaust sampling and full-flow dilution channel CVS dilution sampling equipment. The results showed that the emission characteristics of particulate matter above 23 nm and above 10 nm in the RMC test had the same trend, and the cumulative PN emissions were 1.9×1012 and 2.3×1012 for the whole test cycle, respectively. The PN23 values of dilution sampling were higher than those of direct sampling. The main reason for the difference in PN emission values at the same working modes in RMC and NRSC is the change in DPF capture efficiency caused by the different order of working modes and conditions.

Evaluation of Emission Characteristics and Microstructure of Particulate Matters from Excavation and Restoration Work on Asphalt Concrete Pavement

Road excavation–restoration work, where various construction tasks are performed, may generate large quantities of particulate matter (PM). These PM may accumulate in the surroundings or scatter into the atmosphere, thus affecting the environment and people in the surroundings. This study was conducted as part of a basic research study to reduce scattering PM generated from road excavation–restoration work. This study aimed to investigate the PM10 emission trend for each activity of road excavation–restoration work, and to analyze the activity that yields the highest PM10 emissions. PM were measured by using a particle spectrometer and the vacuum sweep method, by conducting field (level 1) and chamber experiments (level 2). The PM10 emission trends of road-cutting, breaking, removal, excavation, and restoration activities were examined based on field experiments. It was found that the highest PM10 emission was generated from road-cutting activities. The road-cutting activities were performed in an enclosed chamber, and the microstructure and the emission characteristics of PM generated by cutting were analyzed. The PM generated during the cutting activity were analyzed by dividing them into scattered and deposited PM. The results showed that as the cutting depth increased, the scattered PM decreased, while the deposited PM tended to increase. Furthermore, as a result of the microstructural analysis of PM conducted during the cutting activity, it was found that the main components were aggregates instead of the components of asphalt binder.

Emission characteristics of particulate matter emitted from 4- and 2-stroke marine diesel engines under the background of sulfur emission reduction.

With the implementation of sulfur emission regulations, influences of particulate matter (PM) emitted by marine diesel engines on nearshore atmospheric environment and human health are of increasingly concern. Whatever measures are chosen to meet sulfur emission regulations, the emission characteristic and influencing factors of PM should also be determined. In this study, number and mass emissions, volatility, main composition, and toxicity of PM from marine 4- and 2-stroke diesel engines were investigated. It was found that the size distribution curves of particle number are multiple peaks. Fuels and engines types influence the modal distribution of particles number concentration. For light diesel oil and low-sulfur heavy fuel oil (HFO), particle number was dominated by nucleation and accumulation mode respectively, and particle mass was dominated by accumulation mode. Reduction of fuel sulfur content (FSC) could reduce the particles mass, number and fraction of volatile substance emissions, and small-size particles had the most volatility. Particulate organic carbon (OC) was the main substance, especially for marine 2-stroke diesel engine burning HFO (high- or low-sulfur), while particulate OC contained a large number of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The PAHs also had very high toxicity when the engine was burning HFO. The use of low-sulfur HFO cannot make the marine diesel engine meet the current and upcoming PM regulations, and after-treatment technologies or cleaning fuel should be needed.

Agri-Environment Atmospheric Real-Time Monitoring Technology Based on Drone and Light Scattering

The emission of particulate matter (PM) from agricultural activities, such as concentrated animal feeding, straw combustion, and mechanized harvest, is a hot issue in the sustainable development of agriculture, which has attracted more and more attention from government departments and researchers. However, the research on the transport of particulate matter in the agri-environment still lacks flexible and efficient measurement methods to obtain real-time and accurate spatial distribution data. The objective of our study is to produce a new intelligent platform for agri-environment atmospheric monitoring with high mobility, temporal and spatial resolution, and remote data transmission function to overcome the shortcomings of traditional atmospheric particulate matter monitoring stations, such as small particle size range, immovability, and high cost. Through the light scattering sensor, microcontroller, and wireless data transmission device assembled on the high-mobility drone, the platform could measure the mass concentration of PM2.5, PM10, and TSP at different spatial points in the agri-environment and transmit the measurement data to the receiving device on the ground through three modes: CLOUD, TCP, and UDP. We also developed monitoring software based on the Android platform, which could complete the connection of device and real-time monitoring of measurement data on the ground. Compared with stationary measurement devices, the biggest advantage of our mobile monitoring system is that it has the ability to measure the concentration of TSP and the vertical distribution of PM, which is very important for the research of agricultural environmental particulate matter emission characteristics. After the sensor and communication performance experiments, the sensors had high consistency in the overall change trend, and the communication accuracy rate was high. We carried out a flight measurement comparison experiment at the Wenhua Road Campus of Henan Agricultural University, and the measurement data were highly consistent with the data from the national monitoring stations. We also conducted an agri-environmental atmospheric measurement experiment in Muzhai Village and obtained the vertical distribution data of PM concentration at the nearby measuring point when the harvester was working. The results showed that after the harvester worked for a period of time, the PM2.5, PM10, and TSP concentrations reached the maximum at the altitude of 20 m at the measurement point, which were 80, 198, and 384 μg/m3, respectively, 2.64~3.10 times the particle concentration in the environment before the harvester began to work. Our new platform had high mobility, sensitive reading, and stable communication during the experiment, and had high application value in agricultural environmental monitoring.

Effect of Densification on Biomass Combustion and Particulate Matter Emission Characteristics

The effect of biomass densification on combustion characteristics and particulate matter (PM) emission was studied in this work by means of thermogravimetric, combustion kinetic, and PM analyses with respect to the size distribution and elementary composition. Cornstalk as a typical agricultural biomass residue and camphorwood as a woody biomass were used in the experiment for comparison. It can be concluded that the biomass densification increases the ignition, burnout, and composite combustion indexes, leading to a better performance of biomass combustion. The main reaction mechanism of cornstalk pellets can be well-expressed with the chemical reaction series model, whereas the diffusion mechanism and chemical reaction series models can be applied to the combustion of camphorwood pellets. The biomass densification has little effect on the composition of PM but significantly changes the yield of PM. The influence of biomass densification on PM emission is related to the biomass properties. The densification significantly reduces the PM emission for cornstalk but significantly increases the yield of particles of aerodynamic cutoff diameters less than 1μm (PM1) for camphorwood.

Review of morphological and chemical characteristics of particulates from compression ignition engines

Particulates from compression ignition (CI) engines have received serious attention in the last two decades. CI engines emit higher particulate matter (PM) and nitrogen oxides (NOx) than spark ignition (SI) engines. Both these species are harmful to human health and the environment. Compared to NOx emissions, PM constitutes many more chemical species in solid and liquid phases. This review paper focuses on soot morphology and chemical characterization of PM emissions from CI engines. Effects of different fuels, lubricating oil, and engine operating conditions on particulate characteristics are analyzed exhaustively. The first part of this paper focuses on the effects of particulates on living organisms, the consequences of exposure to diesel particulates, and the composition of diesel particulates. In recent decades, micro and nano-scale characteristics of PM have been exhaustively investigated to understand its structure, formation, and chemical functionalities. Typically, particulates comprise of elemental carbon (EC), organic carbon (OC), polycyclic aromatic hydrocarbons (PAHs), the soluble organic fraction (SOF), and trace metals. This paper summarizes most aspects of diesel particulate emissions for the benefit of active researchers in the field and underlines the importance of particulate emission reduction from the CI engines. Diesel combustion generates particles with enormous long-chain aggregates of smaller sizes and immature soot particles. Low-temperature combustion (LTC) modes and oxygenated fuels reduce the soot emissions and generate compact/clustered aggregates. Oxygenated fuels in CI engines produce more nucleation mode particles (NMPs) and high-reactivity soot aggregates. Higher trace metal concentrations were observed in diesel origin particulates than biofuel origin particulates. Biodiesel origin particulates possess higher mutagenicity and carcinogenicity because of nitro-PAHs. Transient engine operations cause higher particulates than steady-state engine operations.

A proactive approach to execute targeted particulate matter control measures for construction works

Particulate matter (PM) refers to the solid or liquid particles suspended in the air that harm human and the environment. PM emissions from the construction industry have become a critical concern for human health. Previous studies have been performed to minimize PM emissions using various control measures. However, they failed to mitigate the PM concentrations to optimum levels advocated by occupational health and safety standards. In this study, we identified the maximum PM exposure zones in various construction activities to reduce the overall PM exposure by considering the spatiotemporal characteristics of PM emissions. The exposure profile assessment of various PM sizes showed that activities such as cutting, drilling of M20 and M25 concrete slabs, mixing and sanding of M25 concrete, and plastering demonstrated maximum PM exposure at the breathing height (1.5 m above the ground). We found that the PM concentration increased with an increase in the density of the material (i.e., from wood to M25 concrete). Moreover, this study clearly describes the necessity for the proper positioning of the control measures (i.e., water spray system and exhaust ventilation) based on the size-dependent PM exposure profiles and maximum PM exposure zone. The health risk of a worker inside the maximum PM exposure zone was observed as potential according to the United States Environmental Protection Agency (USEPA) guidelines (i.e., hazard index = 10−4 to 10−6). This study directs construction professionals to focus on appropriate positioning of the PM countermeasures by targeting the maximum exposure zones and size-dependent PM exposure profiles for various high-PM-emitting activities.

Assessing Impacts of Additives on Particulate Matter and Volatile Organic Compounds Produced from the Grilling of Meat

Cooking fumes are an important source of volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds. The additive is wildly applied in grilling meat for flavor improvement. However, the effects of additives on cooking fumes emissions, such as volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds, in meat grilling have not been studied. The impact of four additives, including white pepper, salt, garlic powder, and compound marinade, on the emission characteristics of cooking fumes from the grilling meat was investigated. The concentrations of VOCs and carbonyl compounds in the cooking fumes were analyzed by TD-GC/MS and HPLC, respectively. The PM emission characteristics (mass concentration and size distribution) were measured by DustTrak DRX aerosol monitor in real-time. Results showed that the application of white pepper, salt, garlic powder, and mixed spices could significantly reduce the total particles mass concentration (TPM) emissions during meat-grilling by 65.07%, 47.86%, 32.87%, and 56.01%, respectively. The mass concentration of PM during meat-grilling reached maximum values ranging from 350 to 390 s and gradually fell at the final stages of grilling. The total concentration of 22 representative VOCs emitted from the grilling was significantly increased in grilling meat marinated with compound additives. Aromatic hydrocarbons were the predominant VOCs species, followed by ketone compounds. During the grilling process, formaldehyde, acetaldehyde, propionaldehyde, and acetone were major carbonyl compounds. The low molecular weight carbonyl compounds (C1–C3) in cooking fumes were dominant carbonyl compounds.

Emission characteristics of particulate matter emitted by typical off-road construction machinery.

Off-road machinery, especially construction equipment, is one of the most important pollutant sources of the deterioration in the air quality of Chinese urban areas owing to its large quantity and to the absence of stringent emission requirements. In this study, we used a portable emission measurement system (PEMS) to measure the exhaust pollutant emission characteristics for 13 pieces of construction machinery including excavators and hydraulic crushers under different working conditions, such as real-world operating condition, free accelerating condition, and overloading condition, innovatively adopting the method of synchronizing video recording and emission measurement to divide the operation process of construction machinery under different working conditions into different action stages. In addition, the relationship between the emission characteristics and the maintenance history of 13 pieces of construction machinery was analyzed. The present study exploits this recent progress to enrich the measurement method of off-road mobile machinery light absorption coefficient (LAC), which does not depend on the measurement environment and the type of equipment. There are three significant findings from the study that can be noted. To begin with, the exhaust LAC in the excavation operation stage was the highest in the real-world operating condition. The main reason for it is that the engine load was suddenly increased during this stage; due to the response lag characteristics of the turbocharger, the intake charge was delayed, so the quality of oil and gas mixture in the cylinder becomes worse, and the concentration of local mixture is higher. Therefore, insufficient combustion of the mixture leads to a large amount of soot formation. Second, when the real-world operation is unavailable, the free accelerating condition was not applicable, but the overflow loading condition is suitable for replacing the real-world operating condition to measure the excavator exhaust LAC. Finally, as for in-use construction machinery, regular maintenance is an effective measure to reduce the engine exhaust LAC. Our findings contribute to improving the efficiency and accuracy of the environmental protection department's evaluation of the exhaust LAC of off-road mobile machinery and promoting the application of different technologies for high-emission off-road mobile machinery to reduce pollutant emissions so that it can continue to be used.